JET PROPULSION BOAT AND PROPULSION BOAT

- KAWASAKI MOTORS, LTD.

A jet propulsion boat includes a boat body, an operation part operated by a driver on the boat body, a turning posture detector that detects a turning posture of the boat body when a driver performs operation of turning the boat body, a behavior adjustment actuator that adjusts a behavior of the boat body, and a controller that controls the behavior adjustment actuator based on the turning posture detected by the turning posture detector.

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Description
BACKGROUND Technical Field

The present disclosure relates to a jet propulsion boat and a propulsion boat that move on the water.

Background Art

Known types of a propulsion boat include a jet propulsion boat disclosed in US 2013/0102206 A1. To improve convenience of a jet propulsion boat (propulsion boat), increase in a degree of freedom in operation is desirable.

SUMMARY

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a jet propulsion boat and a propulsion boat that each have a high degree of freedom in operation.

To solve the above problem, a jet propulsion boat according to an aspect of the present disclosure includes a boat body, a first propulsion device that imparts propulsion force to the boat body by injection of a jet water flow, and a second propulsion device that imparts propulsion force to the boat body with a mechanism independent of the first propulsion device.

A propulsion boat according to another aspect of the present disclosure planes on water in an inclined posture in which a bow rises, the propulsion boat including a boat body, a first propulsion device that imparts propulsion force to the boat body, the propulsion force capable of moving the propulsion boat in a planing state, and a second propulsion device that imparts propulsion force to the boat body with a mechanism independent of the first propulsion device, in which the second propulsion device includes an impeller disposed in a water passage through which water flows, and a power source that rotationally drives the impeller to inject a water flow from the water passage, and the water passage includes an entrance formed at a position exposed above from a water surface when the propulsion boat is in a planing state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially broken side view of a jet propulsion boat according to a first embodiment of the present disclosure;

FIG. 2 is a plan view of the jet propulsion boat;

FIG. 3 is a plan sectional view schematically illustrating structure of a second propulsion device of the jet propulsion boat;

FIG. 4A is a schematic side view of the jet propulsion boat in a non-planing state;

FIG. 4B is a schematic side view of the jet propulsion boat in a planing state;

FIG. 5 is a perspective view illustrating an operation lever for operating the second propulsion device;

FIG. 6 shows a relationship between a tilting direction of the operation lever and operation (traveling direction) of the jet propulsion boat in a table format;

FIG. 7 is a side view illustrating a jet propulsion boat according to a second embodiment of the present disclosure;

FIG. 8 is a partial plan sectional view of the jet propulsion boat;

FIG. 9 is a partial plan view illustrating a jet propulsion boat according to a third embodiment of the present disclosure; and

FIG. 10 is a sectional view illustrating structure of a second propulsion device of the jet propulsion boat.

 DETAILED DESCRIPTION

Hereinafter, a jet propulsion boat according to an embodiment of the present disclosure will be described with reference to the drawings. Although some of the drawings indicate directions of front, rear, left, and right, these directions each align with a direction viewed from a driver on the jet propulsion boat.

(1) FIRST EMBODIMENT [Configuration of Jet Propulsion Boat]

FIG. 1 is a partially broken side view of a jet propulsion boat 1 according to a first embodiment of the present disclosure, and FIG. 2 is a plan view of the jet propulsion boat 1. The jet propulsion boat 1 jets a water flow backward to move on the water in reaction to the water flow. The jet propulsion boat 1 according to the present embodiment is a straddle-type personal watercraft also called PWC. Thus, the jet propulsion boat 1 is abbreviated below as a PWC 1. The PWC 1 includes a boat body 10, a first propulsion device 2 of an engine type that imparts propulsion force to the boat body 10 by injection of a jet water flow, and a second propulsion device 3 that imparts propulsion force to the boat body 10 with an electric mechanism independent of the first propulsion device 2.

The boat body 10 includes a hull 11 and a deck 12 overlying the hull 11. The hull 11 and the deck 12 are joined to each other over the entire circumference by a gannel line 10G. The deck 12 includes a front hatch 17, a front bumper 18, and a rear cover 19. The front hatch 17 is configured to cover an upper surface opening of a cargo storage space formed in a front part of the deck 12. The front bumper 18 is configured to cover a foremost part of the boat body 10. The rear cover 19 is disposed to cover the hull 11 behind a seat 14 described later, and is used when an occupant returns from the water to the boat body 10, for example.

The deck 12 is provided with a handle 13, the seat 14, and a display 15. The seat 14 allows a driver M who drives the PWC 1 to sit thereon. The handle 13 is a steering handle operated by the driver M for steering the PWC 1. The display 15 displays various types of information regarding operation of the PWC 1, such as moving speed, a remaining amount of fuel, and an operation mode.

The seat 14 extends in a longitudinal direction (front-rear direction) behind the handle 13 and is disposed to partially cover an upper surface of the deck 12. The seat 14 may be a seat on which at least the driver M can sit. That is, the seat 14 may be a multi-seat on which not only the driver M but also a fellow passenger can sit, or may be a single-seat on which only the driver M can sit.

The first propulsion device 2 includes an engine 5 of an internal combustion type, a jet pump 6 that is driven by the engine 5 and injects water, and a reverse bucket 7 (FIG. 1) disposed at an outlet part of the jet pump 6.

The engine 5 is a power source that generates power for driving the jet pump 6, and includes, for example, a water-cooled four-stroke multicylinder engine using gasoline as fuel. The engine 5 is accommodated in an engine room ER formed inside the hull 11. The engine 5 includes a crank shaft 30 extending in the longitudinal direction as an output shaft.

The engine 5 has maximum output, or the first propulsion device 2 has maximum output, the maximum output being set to a value that allows the PWC 1 to move in a planing state with propulsion force generated by a jet water flow from the jet pump 6. That is, the first propulsion device 2 is a main propulsion device which has relatively high output and is capable of moving the PWC 1 in a planing state in which the boat body 10 is inclined in a direction in which the bow rises. The propulsion force described above that can be generated by the first propulsion device 2 is larger than that of the second propulsion device 3 that is an electric auxiliary propulsion device.

The jet pump 6 generates a jet water flow injected backward from the boat body 10.

Specifically, the jet pump 6 generates a jet water flow by pressurizing and accelerating water taken into the boat body 10, and injects the generated jet water flow backward from the boat body 10. This backward injection of the jet water flow generates propulsion force for moving the boat body 10 forward.

The jet pump 6 is disposed in a rear central part of the boat body 10. The boat body 10 includes an impeller passage 37 at a position corresponding to the jet pump 6. The impeller passage 37 includes a water suction port 36 as an inlet formed at the center in a width direction of a bottom surface 11A of the hull 11, and is formed to pass through a rear part of the hull 11 in the longitudinal direction.

As mainly illustrated in FIG. 1, the jet pump 6 includes a pump shaft 31, a pump impeller 32, a stator vane 33, a pump case 34, and a jet nozzle 35.

The pump shaft 31 is coaxially coupled to a rear end of the crank shaft 30. The pump shaft 31 has a rear part inserted into the impeller passage 37. The pump impeller 32 is attached to a rear end part of the pump shaft 31, and is accommodated inside the impeller passage 37 in a state of being rotatable around an axis of the pump shaft 31. Driving force of the engine 5 is transmitted to the pump impeller 32 via the crank shaft 30 and the pump shaft 31 to axially rotate the pump impeller 32. The pump impeller 32 rotates to generate a jet water flow. The stator vane 33 is attached behind the pump impeller 32, and straightens the jet water flow generated by the pump impeller 32. The pump case 34 is disposed behind the pump impeller 32 and rotatably supports the rear end part of the pump shaft 31.

The jet nozzle 35 includes an injection port 39 for injecting a jet water flow generated by the pump impeller 32, and is disposed behind the pump case 34. The jet nozzle 35 including a passage has a tapered shape in which a passage cross-sectional area decreases toward the back. The jet nozzle 35 is supported by the boat body 10 via a support shaft extending in an up-down direction, and thus capable of swinging to the left and right.

The jet nozzle 35 is linked with the handle 13 via a cable or the like to swing left and right about the support shaft in response to steering of the handle 13. When the jet nozzle 35 is swung using the handle 13, an injection direction of a jet water flow from the injection port 39 is changed to the left and right, thereby changing a traveling direction of the PWC 1. In other words, the handle 13 is a steering handle capable of changing a traveling direction when the PWC 1 is moved using the first propulsion device 2 of an engine type. As described above, the traveling direction can be changed using the handle 13 during movement (mainly during planing) using the first propulsion device 2 of an engine type, and the movement always involves movement in the longitudinal direction.

In contrast, during movement using the second propulsion device 3 of an electric type, the traveling direction is changed by operating an operation lever 25 to be described later instead of operating the handle 13. Although details will be described later, the second propulsion device 3 can move the PWC 1 not only in a non-planing state, but also in a direction other than the longitudinal direction, i.e., in a lateral direction (left-right direction).

The impeller passage 37 includes a rear end part formed as a tapered part 38 in which a passage cross-sectional area decreases toward the back. The tapered part 38 includes a rear part inserted into the jet nozzle 35. Water taken into the impeller passage 37 from the water suction port 36 is fed to the tapered part 38 and the jet nozzle 35 while being pressurized and accelerated in accordance with rotation of the pump impeller 32, and is injected at high speed from an outlet of the jet nozzle 35, the outlet having a narrowed passage cross-sectional area, i.e., from the injection port 39.

The reverse bucket 7 is supported by a component (pump cover) constituting a lower rear end part of the boat body 10 via a support shaft extending in the lateral direction, thereby capable of rotating in the up-down direction. Specifically, the reverse bucket 7 is movable between a forward position illustrated in FIG. 1 at which the reverse bucket 7 is rotated upward without covering the injection port 39 of the jet nozzle 35 and a reverse position at which the reverse bucket 7 is rotated downward to cover the injection port 39 of the jet nozzle 35 from behind. When the reverse bucket 7 is at the forward position (FIG. 1), the PWC 1 moves forward, and when the reverse bucket 7 is at the reverse position, the PWC 1 moves backward. The deck 12 is provided with a shift lever for switching the reverse bucket 7 between the forward position and the reverse position.

The handle 13 is disposed above a front part of the deck 12. As illustrated in FIG. 2, the handle 13 is provided with an accelerator 21, a start switch 22, and a stop switch 23. The accelerator 21 is an operation lever for adjusting moving speed of the PWC 1 by increasing or decreasing output of the engine 5 when the PWC 1 moves using the first propulsion device 2 of an engine type. The start switch 22 is configured to start the engine 5. The stop switch 23 is configured to stop the engine 5. The start switch 22 and the stop switch 23 in the present embodiment are configured by a common push-button switch that is provided at a position opposite (left side) to the accelerator 21 on the handle 13.

FIG. 3 is a plan sectional view schematically illustrating structure of the second propulsion device 3. As mainly illustrated in FIGS. 2 and 3, the second propulsion device 3 includes a plurality of thrusters 8A, 8B, 9 of an electric type. Specifically, the second propulsion device 3 includes a pair of left and right longitudinal thrusters 8A, 8B disposed in a rear part of the boat body 10, and a lateral thruster 9 disposed at a front part of the boat body 10. The second propulsion device 3 in the present embodiment is an auxiliary propulsion device prepared for moving the PWC 1 at low speed and with low noise. Thus, the second propulsion device 3 (thrusters 8A, 8B, 9) has a maximum output that is set to be lower than that of the first propulsion device 2 of an engine type including the jet pump 6. The second propulsion device 3 driven at the maximum output causes vibration and noise that are smaller than vibration and noise caused when the first propulsion device 2 is driven at the maximum output.

The pair of longitudinal thrusters 8A, 8B generate propulsion force for moving the boat body 10 in the longitudinal direction. The longitudinal thruster 8A is disposed on the left side of the jet pump 6, i.e., in a left rear part of the boat body 10. The longitudinal thruster 8B is disposed on the right side of the jet pump 6, i.e., in a right rear part of the boat body 10. In other words, the pair of longitudinal thrusters 8A, 8B are respectively disposed on left and right side parts of the rear part of the boat body 10 to be disposed on the left and right across a center axis L1 (FIG. 3) of the boat body 10 extending in the longitudinal direction. Alternatively, the pair of longitudinal thrusters 8A, 8B are disposed at respective positions displaced from each other in different directions with respect to the center of gravity G (FIG. 3) of the PWC 1. The pair of longitudinal thrusters 8A, 8B in the present embodiment are respectively disposed on the left and right side parts of the boat body 10 to be symmetrical with respect to the center axis L1 or the center of gravity G of the PWC 1. The longitudinal thruster 8A on the left side is referred below to as a left longitudinal thruster 8A, and the longitudinal thruster 8B on the right side is referred below to as a right longitudinal thruster 8B as appropriate.

The left longitudinal thruster 8A includes an electric motor 51, a propeller shaft 52, and an impeller 53. The electric motor 51 is an electric power source (first power source) that rotationally drives the impeller 53. The propeller shaft 52 couples the electric motor 51 to the impeller 53. The impeller 53 rotates by receiving driving force of the electric motor 51, and generates a water flow using the rotation.

The boat body 10 includes a left water passage 41 at a position corresponding to the left longitudinal thruster 8A. The left water passage 41 passes through a left rear part of the hull 11 in the longitudinal direction to allow a front opening 41a opened on a left side surface of the rear part of the hull 11 to communicate with a rear opening 41b opened on a rear surface of the hull 11 as illustrated in FIG. 3. The front opening 41a opens diagonally forward left, i.e., forward and leftward, and the rear opening 41b opens substantially straight backward. In other words, the left water passage 41 is a bent or curved passage including a first part extending obliquely backward from the front opening 41a and a second part extending backward from a rear end of the first part to reach the rear opening 41b. The rear opening 41b is opened parallel to a corresponding opening (rear opening 42b to be described later) of the right longitudinal thruster 8B.

The propeller shaft 52 has a rear part inserted into the left water passage 41. The impeller 53 is attached to a rear end of the propeller shaft 52, and is accommodated inside the left water passage 41 in a state of being rotatable around an axis of the propeller shaft 52. The driving force of the electric motor 51 is transmitted to the impeller 53 via the propeller shaft 52 to rotate the impeller 53 around its axis. The impeller 53 is rotated to cause water introduced into the left water passage 41 to be injected from one end (the front opening 41a or the rear opening 41b) of the left water passage 41 to generate a water flow flowing in the longitudinal direction. In other words, the left longitudinal thruster 8A is disposed in a posture in which an injection axis of the water flow, i.e., the axis of the impeller 53, faces the longitudinal direction.

The electric motor 51 in the present embodiment can perform a forward rotation operation of rotating the impeller 53 in a direction causing a backward water flow to be generated and a reverse rotation operation of rotating the impeller 53 in a direction causing a forward water flow to be generated. During the forward rotation of the electric motor 51, the water flow generated by the impeller 53 is injected backward from the rear opening 41b of the left water passage 41 as indicated by an arrow D1 in FIG. 3. This backward injection of the water flow imparts forward propulsion force to the boat body 10 to move the boat body 10 forward. In contrast, during the reverse rotation of the electric motor 51, the water flow generated by the impeller 53 is injected obliquely forward from the front opening 41a of the left water passage 41 as indicated by an arrow D2 in FIG. 3. This forward injection of the water flow imparts backward propulsion force to the boat body 10 to move the boat body 10 backward. As described above, the left longitudinal thruster 8A can be switched between a backward injection mode in which a water flow is injected backward to impart forward propulsion force to the boat body 10 and a forward injection mode in which a water flow is injected forward to impart backward propulsion force to the boat body 10.

The right longitudinal thruster 8B also has structure similar to that of the left longitudinal thruster 8A. That is, the right longitudinal thruster 8B includes an electric motor 61 (power source or second power source), a propeller shaft 62, and an impeller 63.

The boat body 10 includes a right water passage 42 at a position corresponding to the right longitudinal thruster 8B. The right water passage 42 passes through a right rear part of the hull 11 in the longitudinal direction, and has a shape symmetrical to the left water passage 41 described above. That is, the right water passage 42 allows the front opening 42a opened in a right side surface of the rear part of the hull 11 to communicate with the rear opening 42b opened on the rear surface of the hull 11. The front opening 42a opens diagonally forward right, and the rear opening 42b opens substantially straight backward.

The propeller shaft 62 has a rear part inserted into the right water passage 42. The impeller 63 is attached to a rear end of the propeller shaft 62, and is accommodated inside the right water passage 42 in a state of being rotatable around an axis of the propeller shaft 62. The impeller 63 is rotationally driven by the electric motor 61 to generate a water flow in the longitudinal direction through the right water passage 42. In other words, the right longitudinal thruster 8B is disposed in a posture in which an injection axis of the water flow, i.e., the axis of the impeller 63, faces the longitudinal direction.

Similarly to the electric motor 51 of the left longitudinal thruster 8A described above, the electric motor 61 can perform forward rotation and reverse rotation. During the forward rotation of the electric motor 61, a water flow is injected backward from the rear opening 42b of the right water passage 42 to impart forward propulsion force to the boat body 10 (backward injection mode) as indicated by an arrow D3 in FIG. 3. In contrast, during the reverse rotation of the electric motor 61, a water flow is injected diagonally forward from the front opening 42a of the right water passage 42 to impart backward propulsion force to the boat body 10 (forward injection mode) as indicated by an arrow D4 in FIG. 3.

As described above, the left longitudinal thruster 8A (right longitudinal thruster 8B) can be switched between the backward injection mode in which a water flow is injected from the rear opening 41b (42b) of the water passage 41 (42) and the forward injection mode in which a water flow is injected from the front opening 41a (42a) of the water passage 41 (42). The backward injection mode allows the pair of left and right rear openings 41b, 42b to function as outlets for a water flow injected backward, and the forward injection mode allows the pair of left and right front openings 41a, 42a to function as outlets for a water flow injected forward. The rear openings 41b, 42b in the backward injection mode, and the rear openings 41a, 42a in the forward injection mode, correspond to “a pair of longitudinal openings” in the present disclosure. In other words, the water passages 41, 42 for the corresponding left and right longitudinal thrusters 8A, 8B have a pair of longitudinal openings opened in the longitudinal direction at two positions on the left and right across a center axis of the boat body 10 extending in the longitudinal direction.

Here, the left longitudinal thruster 8A and the right longitudinal thruster 8B are disposed symmetrically across the center axis L1 of the boat body 10 (or the center of gravity G of the PWC 1). Thus, when only one of the thrusters 8A, 8B injects a water flow, turning force acts on the boat body 10. For example, when only the left longitudinal thruster 8A is driven in the backward injection mode, forward propulsion force is generated in a left side part of the boat body 10, and as a result, turning force for rotating the boat body 10 clockwise acts on the boat body 10. Similarly, when only the right longitudinal thruster 8B is driven in the backward injection mode, forward propulsion force is generated in a right side part of the boat body 10, and as a result, turning force for rotating the boat body 10 counterclockwise acts on the boat body 10. In contrast, when both the left and right longitudinal thrusters 8A, 8B are driven at equal output in the backward injection mode, turning forces of the longitudinal thrusters 8A, 8B are mutually cancelled, and thus substantially no turning force acts on the boat body 10. The same applies to the forward injection mode.

The lateral thruster 9 generates propulsion force for moving the boat body 10 in the lateral direction (width direction). The lateral thruster 9 is disposed near a front end part of the boat body 10, the front end part being positioned in front of the handle 13.

The lateral thruster 9 includes an electric motor 71, a propeller shaft 72, an impeller 73, and a gear mechanism 74. The gear mechanism 74 is a bevel gear mechanism linked with an output shaft of the electric motor 71. The propeller shaft 72 couples the gear mechanism 74 to the impeller 73. The gear mechanism 74 receives rotation from the electric motor 71 and changes a direction of the rotation by 90 degrees, and then transmitted the rotation to the impeller 73. As a result, the impeller 73 is rotated, and a water flow is generated by the rotation of the impeller 73.

The boat body 10 includes a front water passage 43 at a position corresponding to the lateral thruster 9. The front water passage 43 passes through a front part of the hull 11 in the lateral direction to allow a left opening 43a opened in a left side surface of the front part of the hull 11 to communicate with a right opening 43b opened in a right side surface of the front part of the hull 11 and as illustrated in FIG. 3.

The electric motor 71 is disposed inside the hull 11 behind the front water passage 43. On the other hand, the propeller shaft 72, the impeller 73, and the gear mechanism 74 are accommodated inside the front water passage 43. The driving force of the electric motor 71 is transmitted to the impeller 73 via the gear mechanism 74 and the propeller shaft 72 to rotate the impeller 73 around its axis. The impeller 73 is rotated to cause water introduced into the front water passage 43 to be injected from one end (the left opening 43a or the right opening 43b) of the front water passage 43 to generate a water flow flowing in the lateral direction. In other words, the lateral thruster 9 is disposed in a posture in which an injection axis of the water flow, i.e., the axis of the impeller 73, faces the lateral direction.

The electric motor 71 in the present embodiment can perform a forward rotation operation of rotating the impeller 73 in a direction causing a rightward water flow to be generated and a reverse rotation operation of rotating the impeller 73 in a direction causing a leftward water flow to be generated. During the forward rotation of the electric motor 71, the water flow generated by the impeller 73 is injected rightward from the right opening 43b of the front water passage 43 as indicated by an arrow D5 in FIG. 3. This rightward injection of the water flow imparts leftward propulsion force to the boat body 10 to move the boat body 10 leftward. In contrast, during the reverse rotation of the electric motor 71, the water flow generated by the impeller 73 is injected leftward from the left opening 43a of the front water passage 43 as indicated by an arrow D6 in FIG. 3. This leftward injection of the water flow imparts rightward propulsion force to the boat body 10 to move the boat body 10 rightward. As described above, the lateral thruster 9 can be switched between a rightward injection mode in which a water flow is injected rightward to impart leftward propulsion force to the boat body 10 and a leftward injection mode in which a water flow is injected leftward to impart rightward propulsion force to the boat body 10.

Here, the lateral thruster 9 is disposed in front of the center of gravity G of the PWC 1. Thus, when the lateral thruster 9 is driven in the rightward injection mode or the leftward injection mode, a turning force acts on the boat body 10. For example, when the lateral thruster 9 is driven in the rightward injection mode, leftward propulsion force is generated in the front part of the boat body 10, and as a result, turning force for rotating the boat body 10 counterclockwise acts on the boat body 10. Alternatively, when the lateral thruster 9 is driven in the leftward injection mode, rightward propulsion force is generated in the front part of the boat body 10, and as a result, turning force for rotating the boat body 10 clockwise acts on the boat body 10.

As described above, the second propulsion device 3 includes the three thrusters 8A, 8B, and 9 each using an electric motor as a power source. Various conceivable examples of a method for supplying electric power to the electric motors 51, 61, and 71 of the corresponding thrusters 8A, 8B, and 9 include a case in which a common battery supplies electric power to the electric motors 51, 61, and 71. Conceivable examples of the case include use of a common battery for supplying electric power to not only electric components in the first propulsion device 2 but also the electric motors 51, 61, and 71. This configuration enables efficient layout of components in the hull 11.

Here, heights of the water passages 41, 42, and 43 of the corresponding thrusters 8A, 8B, and 9 will be described in detail. Each of the water passages 41, 42, and 43 includes an entrance with a height that is set based on each of water surface heights when the PWC 1 is in the planing state and the non-planing state. Specifically, the entrance of each of the water passages 41, 42, and 43 is formed at a position lower than a water surface S1 during non-planing illustrated in FIG. 4A and higher than a water surface S2 during planing illustrated in FIG. 4B. The entrance of each of the water passages 41, 42, and 43 is formed at the position higher than the water suction port 36 of the impeller passage 37 and the injection port 39 of the jet nozzle 35.

For example, the entrance of the water passage of the left longitudinal thruster 8A, i.e., each of the front and rear openings 41a, 41b of the left water passage 41, is formed at a position lower than the water surface S1 during non-planing, higher than the water surface S2 during planing, and higher than the water suction port 36 and the injection port 39. The same applies to the entrance of another water passage. That is, the front and rear openings 42a, 42b of the right water passage 42 of the right longitudinal thruster 8B, and the left and right openings 43a, 43b of the front water passage 43 of the lateral thruster 9, are formed at respective positions lower than the water surface S1 during non-planing, higher than the water surface S2 during planing, and higher than the water suction port 36 and the injection port 39.

Here, the term, “planing”, of the PWC 1 means that the PWC 1 moves on the water surface while sliding thereon in an inclined posture in which the bow rises upward from the water surface. The present embodiment allows the PWC 1 to obtain the planing state when the PWC 1 is moved forward at a predetermined speed or more by using the first propulsion device 2 of an engine type including the jet pump 6. The predetermined speed, i.e., speed at which the PWC 1 transitions to the planing state, is 30 km/h or more and 50 km/h or less, for example. In other words, the entrance of each of the water passages 41, 42, and 43 in the present embodiment is formed at a height at which the entrance is exposed above the water surface S2 (FIG. 4B) when the PWC 1 is planing forward at the predetermined speed or more and the second propulsion device 3 is not used. Additionally, the entrance of each of the water passages 41, 42, and 43 is formed at a height at which the entrance is positioned below the water surface S1 (FIG. 4A), i.e., the entrance is immersed in the water, during non-planing in which the bow does not rise upward as described above because the PWC 1 is stopped or is moved at sufficiently low speed. The planing of the PWC 1 may be defined as the planing state when the center axis L1 of the boat body 10 extending in the horizontal direction is inclined by 3 degrees or more in a direction in which the bow rises.

As described above, the entrances of the respective water passages 41, 42, 43 in the present embodiment are located higher than the water surface S2 during planing, so that water is less likely to flow into the entrances of the respective water passages 41, 42, 43 during planing of the PWC 1. This configuration enables preventing the water passages 41, 42, 43 from resisting planing, so that the PWC 1 planes smoothly. Additionally, the entrance of each of the water passages 41, 42, 43 is located at a position lower than the water surface S1 during non-planing to enable drainage through each of the water passages 41, 42, 43 when the PWC 1 is moved at low speed, so that the second propulsion device 3 can be used as a propulsion source for low-speed movement without any trouble.

FIG. 3 illustrates a plan view in which the entrance of each of the water passages 41, 42, 43 is formed at a position away from the center of gravity G of the PWC 1 in the longitudinal direction. For example, the front and rear openings 41a, 41b (42a, 42b) of the left water passage 41 (right water passage 42) are formed at respective positions separated behind the center of gravity G of the PWC 1. The left and right openings 43a, 43b of the front water passage 43 are formed at respective positions separated in front of the center of gravity G of the PWC 1. This configuration facilitates application of a rotation moment to the boat body 10 during turning of the PWC 1 described later.

As illustrated in FIG. 2, the front and rear openings 41a. 41b (42a, 42b) of the left water passage 41 (right water passage 42) are disposed behind the engine 5 that is a power source of the first propulsion device 2, the handle 13, and the seat 14. In contrast, the left and right openings 43a, 43b of the front water passage 43 are disposed in front of the first propulsion device 2, the handle 13, and the seat 14.

Additionally, the front and rear openings 41a, 41b (42a, 42b) of the left water passage 41 (the right water passage 42) are disposed outside the first propulsion device 2 and the seat 14 in the width direction (lateral direction) of the boat body 10. Similarly, the left and right openings 43a, 43b of the front water passage 43 are disposed outside the first propulsion device 2 and the seat 14 in the width direction (lateral direction) of the boat body 10.

As illustrated in FIG. 2, the operation lever 25 is provided near the handle 13 in the deck 12. The operation lever 25 is configured to adjust a traveling direction and speed when the PWC 1 is moved using the second propulsion device 3 of an electric type. As illustrated in FIG. 5, the operation lever 25 in the present embodiment is a so-called joystick, and is supported by a base 26 in a state tiltable in any direction including front, rear, left, and right.

Here, the PWC 1 in the present embodiment can be moved using the second propulsion device 3 only when the engine 5 as the power source of the first propulsion device 2 is stopped. Specifically, although the second propulsion device 3 of an electric type has a lower output than the first propulsion device 2 of an engine type, it is excellent in quietness. The second propulsion device 3 also has an advantage of facilitating not only output adjustment in a region with a low rotation speed but also speed adjustment when slowly driving the PWC 1, as compared with the first propulsion device 2. To take advantage of such characteristics of the second propulsion device 3, the second propulsion device 3 is used in a state where the engine 5 is stopped. In other words, operation of the second propulsion device 3 using the operation lever 25 is effective only while the engine 5 is stopped. Therefore, when using the second propulsion device 3, the driver M operates the operation lever 25 before starting the engine 5 or operates the operation lever 25 after stopping the engine 5.

FIG. 6 illustrates the relationship between a tilting direction of the operation lever 25 and an operation (traveling direction) of the PWC 1, and a control mode of the second propulsion device 3 (each of the thrusters 8A, 8B, 9) in each operation mode, in a table format. With reference to FIG. 6, operation of the PWC 1 and control of the second propulsion device 3 will be described for each tilting direction of the operation lever.

(Forward Movement)

When the operation lever 25 is tilted forward, the PWC 1 is moved forward. During the forward movement of the PWC 1, the left longitudinal thruster 8A and the right longitudinal thruster 8B are each driven in the backward injection mode in which a water flow is injected backward. On the other hand, the lateral thruster 9 is stopped. As a result, forward propulsion force acts on the boat body 10 to move the PWC 1 forward. Specifically, during the forward movement of the PWC 1, the left and right longitudinal thrusters 8A, 8B each inject a water flow backward at equal output. As a result, turning forces about the center of gravity G for the PWC 1 caused by propulsion forces of the respective thrusters 8A, 8B are mutually canceled, and thus the PWC 1 is moved straight forward.

(Backward Movement)

When the operation lever 25 is tilted backward, the PWC 1 is moved backward. During the backward movement of the PWC 1, the left longitudinal thruster 8A and the right longitudinal thruster 8B are each driven in the forward injection mode in which a water flow is injected forward. On the other hand, the lateral thruster 9 is stopped. As a result, backward propulsion force acts on the boat body 10 to move the PWC 1 backward. Specifically, during the backward movement of the PWC 1, the left and right longitudinal thrusters 8A, 8B each inject a water flow forward at equal output. As a result, turning forces about the center of gravity G for the PWC 1 caused by propulsion forces of the respective thrusters 8A, 8B are mutually canceled, and thus the PWC 1 is moved straight backward.

(Clockwise Turning)

When the operation lever 25 is tilted diagonally forward right, the PWC 1 is turned clockwise. During the clockwise turning of the PWC 1, at least the left longitudinal thruster 8A is driven in the backward injection mode. On the other hand, the right longitudinal thruster 8B is stopped or driven in the backward injection mode with smaller output than the left longitudinal thruster 8A. As a result, forward propulsion force acts on the boat body 10, and turning force for turning the boat body 10 clockwise is generated, and thus the PWC 1 is moved diagonally forward right. That is, the PWC 1 is turned clockwise.

When a clockwise turning instruction angle, i.e., a right component of the inclination of the operation lever 25 operated diagonally forward right, is large, the lateral thruster 9 is also used. That is, the lateral thruster 9 is driven in the leftward injection mode in which a water flow is injected leftward when the clockwise turning instruction angle is larger than a predetermined value. As a result, clockwise turning force is increased to turn the PWC 1 clockwise by a relatively large angle. In contrast, when the clockwise turning instruction angle is smaller than the predetermined value, the lateral thruster 9 is stopped.

When the clockwise turning instruction angle is large, the right longitudinal thruster 8B may be driven in the forward injection mode instead of driving the lateral thruster 9 in the leftward injection mode. When the right longitudinal thruster 8B is driven in the forward injection mode, backward propulsion force caused by the right longitudinal thruster 8B is combined with forward propulsion force caused by the left longitudinal thruster 8A driven in the backward injection mode, and thus enabling the boat body 10 to be turned clockwise while suppressing movement of the center of gravity of the boat body 10.

(Counterclockwise Turning)

When the operation lever 25 is tilted diagonally forward left, the PWC 1 is turned counterclockwise. During the counterclockwise turning of the PWC 1, at least the right longitudinal thruster 8B is driven in the backward injection mode. On the other hand, the left longitudinal thruster 8A is stopped or driven in the backward injection mode with smaller output than the right longitudinal thruster 8B. As a result, forward propulsion force acts on the boat body 10, and turning force for turning the boat body 10 counterclockwise is generated, and thus the PWC 1 is moved diagonally forward left. That is, the PWC 1 is turned counterclockwise.

When a counterclockwise turning instruction angle, i.e., a left component of the inclination of the operation lever 25 operated diagonally forward left, is large, the lateral thruster 9 is also used. That is, the lateral thruster 9 is driven in the rightward injection mode in which a water flow is injected rightward when the counterclockwise turning instruction angle is larger than a predetermined value. As a result, counterclockwise turning force is increased to turn the PWC 1 counterclockwise by a relatively large angle. In contrast, when the counterclockwise turning instruction angle is smaller than the predetermined value, the lateral thruster 9 is stopped.

When the counterclockwise turning instruction angle is large, the left longitudinal thruster 8A may be driven in the forward injection mode instead of driving the lateral thruster 9 in the rightward injection mode. When the left longitudinal thruster 8A is driven in the forward injection mode, combination of the left longitudinal thruster 8A and the right longitudinal thruster 8B driven in the backward injection mode enables the boat body 10 to be turned counterclockwise while suppressing movement of the center of gravity of the boat body 10.

(Rightward Sliding)

When the operation lever 25 is tilted rightward, the PWC 1 is slid rightward. During the rightward sliding of the PWC 1, the lateral thruster 9 is driven in the leftward injection mode, and the right longitudinal thruster 8B is driven in the backward injection mode with relatively small output. On the other hand, the left longitudinal thruster 8A is stopped. Leftward injection of the lateral thruster 9 imparts rightward propulsion force to the boat body 10. The leftward injection of the lateral thruster 9 also generates turning force of turning the boat body 10 clockwise. However, this turning force is canceled by backward injection of the right longitudinal thruster 8B. As a result, the PWC 1 is slid rightward.

(Leftward Sliding)

When the operation lever 25 is tilted leftward, the PWC 1 is slid leftward. During the leftward sliding of the PWC 1, the lateral thruster 9 is driven in the rightward injection mode, and the left longitudinal thruster 8A is driven in the backward injection mode with relatively small output. On the other hand, the right longitudinal thruster 8B is stopped. Rightward injection of the lateral thruster 9 imparts leftward propulsion force to the boat body 10. The rightward injection of the lateral thruster 9 also generates turning force of turning the boat body 10 counterclockwise. However, this turning force is canceled by backward injection of the left longitudinal thruster 8A. As a result, the PWC 1 is slid leftward.

Although not illustrated in FIG. 6, the operation lever 25 can also be tilted obliquely backward. That is, when the operation lever 25 is tilted diagonally backward right, the PWC 1 is moved diagonally backward right, and when the operation lever 25 is tilted diagonally backward left, the PWC 1 is moved diagonally backward left. The second propulsion device 3 has a driving mode in each case, the driving mode similar to that during the clockwise turning and the counterclockwise turning illustrated in FIG. 6 except that the left and right longitudinal thrusters 8A, 8B each cause forward injection instead of backward injection.

When the PWC 1 is moved in each direction described above using the second propulsion device 3, moving speed of the PWC 1 can be adjusted by a tilt angle of the operation lever 25. For example, when the PWC 1 is moved forward, the moving speed of the PWC 1 is adjusted to increase as a forward tilting angle of the operation lever 25 increases. The moving speed is adjusted by increasing or decreasing rotation speed (output) of the electric motors 51, 61, 71 in the corresponding thrusters 8A, 8B, 9.

Effects

As described above, the PWC 1 of the present embodiment includes the first propulsion device 2 of an engine type that imparts propulsion force to the boat body 10 by injection of a jet water flow, and the second propulsion device 3 that imparts propulsion force to the boat body 10 with an electric mechanism independent of the first propulsion device 2. Such a configuration enables the first propulsion device 2 and the second propulsion device 3 to be selectively used depending on the situation, and thus the PWC 1 can be improved in operability.

For example, the second propulsion device 3 can be suitably used at the time of movement in a no-wake zone where large waves and noise are not allowed to be generated, or at the time of docking the PWC 1. That is, the second propulsion device 3 of an electric type is excellent in quietness as compared with the first propulsion device 2 of an engine type. Thus, when the second propulsion device 3 is used during movement in the no-wake zone, the PWC 1 can be gently moved without generating a large wave or noise. The second propulsion device 3 of an electric type also facilitates subtle output adjustment as compared with the first propulsion device 2 of an engine type. Thus, when the second propulsion device 3 is used at the time of docking the PWC 1, speed of the PWC 1 for approaching a coast can be adjusted to an appropriate low speed to enable facilitating docking operation.

In contrast, an area allowing the PWC 1 to be freely operated without regulation, such as the no-wake zone, enables the PWC 1 to have an upper limit speed increased by using the first propulsion device 2 of an engine type having a high maximum output, so that the PWC 1 can be moved at a desired speed from a low speed to a high speed.

The second propulsion device 3 in the present embodiment includes the pair of left and right longitudinal thrusters 8A, 8B each having an injection axis of a water flow (the center axis of the impeller) facing the longitudinal direction and the lateral thruster 9 having an injection axis of a water flow facing the lateral direction, so that the PWC 1 can be moved in the longitudinal direction or the PWC 1 can be moved in the lateral direction (width direction) using the corresponding thrusters 8A, 8B, 9. Alternatively, propulsion force for moving the PWC 1 in an oblique direction can be generated by turning on or off the corresponding thrusters 8A, 8B, 9 or setting output of the corresponding thrusters 8A, 8B, 9, so that the PWC 1 can be turned by the propulsion force.

Additionally, an injection direction of a water flow can be changed by using the left and right longitudinal thrusters 8A, 8B and the lateral thruster 9 in the present embodiment, so that the PWC 1 can be moved with a higher degree of freedom. That is, each of the left and right longitudinal thrusters 8A, 8B can be driven in any of the backward injection mode for generating forward propulsion force and the forward injection mode for generating backward propulsion force, and the lateral thruster 9 can be driven in any of the rightward injection mode for generating leftward propulsion force and the leftward injection mode for generating rightward propulsion force. Using the thrusters 8A, 8B, 9 as described above enables the PWC 1 to be moved in any of the front, rear, left, right, and oblique directions, and thus enabling the degree of freedom of movement of the PWC 1 to be expanded.

The PWC 1 provided with not only the longitudinal thrusters 8A, 8B but also the lateral thruster 9 as in the present embodiment enables the PWC 1 to be moved directly sideways by using a water flow in the lateral direction injected from the lateral thruster 9. Moving directly sideways of the PWC 1 as described above cannot be achieved by the first propulsion device 2 using the jet pump 6, and thus is particularly convenient to dock the PWC 1.

The longitudinal thrusters 8A, 8B are respectively disposed on the left and right sides of the jet pump 6 positioned at the center of the rear part of the boat body 10 in the present embodiment, so that these components serving as propulsion sources in the longitudinal direction can be disposed in a well-balanced manner while being distributed left and right. The longitudinal thrusters 8A, 8B respectively disposed on the left and right sides of the boat body 10 also bring an advantage of facilitating adjustment of left-right balance when the PWC 1 is moved using the longitudinal thrusters 8A, 8B. As compared with a case where only one longitudinal thruster is provided, for example, the boat body 10 can be prevented from rotating around the center of gravity G.

Each of the thrusters 8A, 8B, 9 is provided inside the boat body 10 in the present embodiment, so that the thrusters 8A, 8B, 9 can be prevented from resisting movement of the PWC 1. That is, the longitudinal thruster 8A (8B) includes the impeller 53 (63) disposed in the left water passage 41 (right water passage 42) passing through the rear part of the boat body 10 in the longitudinal direction, and the electric motor 51 (61) that rotationally drives the impeller 53 (63). The lateral thruster 9 includes the impeller 73 disposed in the front water passage 43 passing through the front part of the boat body 10 in the lateral direction, and the electric motor 71 that rotationally drives the impeller 73. These configurations prevent a component group including the impellers 53, 63, 73 and the electric motors 51, 61, 71 from being exposed to the outside of the boat body 10. Thus, resistance received by the PWC 1 from water during movement can be reduced, so that energy efficiency during the movement of the PWC 1 can be improved.

Modification

Although the electric motor 51 and the propeller shaft 52 in the left longitudinal thruster 8A are directly coupled in the first embodiment, the electric motor 51 and the propeller shaft 52 may be coupled via a power transmission mechanism. In this case, a direction of an output shaft of the electric motor 51 may be different from an axial direction of the propeller shaft 52. The same applies to the right longitudinal thruster 8B.

Although the power sources (the electric motors 51, 61) of the left and right longitudinal thrusters 8A, 8B are separately provided in the first embodiment, a common power source may be provided. That is, the power source of the left longitudinal thruster 8A and the power source of the right longitudinal thruster 8B may be configured by a common electric motor, and the common electric motor and each of the propeller shafts of the left and right longitudinal thrusters 8A, 8B may be coupled via a power transmission mechanism. In this case, a valve for varying a passage area in each of the water passages 41, 42 for the corresponding left and right longitudinal thrusters 8A, 8B is desirably provided. This configuration enables increasing or reducing the amount of injection of a water flow from each of the longitudinal thrusters 8A, 8B by adjusting an opening degree of the valve while rotating the impeller of each of the left and right longitudinal thrusters 8A. 8B at equal rotation speed, and thus enables achieving operation such as turning of the PWC 1.

Although the water passage 41 (42) for the longitudinal thruster 8A (8B) is formed with the rear opening 41b (42b) that opens substantially straight backward in the first embodiment, the water passage 41 (42) may be formed with the rear opening 41b (42b) that opens obliquely backward. For example, the rear opening 41b (42b) may be opened obliquely backward and outward to form the water passage 41 (42) in a substantially shallow V shape.

Although the first embodiment is described in which an example of using the second propulsion device 3 in a restricted area such as a no-wake zone is described as a preferable use example of the second propulsion device 3 of an electric type (thrusters 8A, 8B, 9), the second propulsion device 3 can be used in various other situations. Conceivable examples of the various other situations include construction in which a control system of the PWC 1 is configured to enable automatic return control of automatically returning the PWC 1 to a falling water point at which a driver falls down and home position control of holding the PWC 1 at a certain point instructed by the driver or the like. When the automatic return control and the home position control are performed using the second propulsion device 3 in such a case, accuracy and safety of each control can be enhanced. For example, the automatic return control is performed to automatically control the electric motors 51, 61, 71 of the corresponding thrusters 8A, 8B, 9 after automatically stopping the engine 5, thereby returning the PWC 1 to the falling water point of the driver. The home position control is performed to automatically stop the engine 5 and automatically control the electric motors 51, 61, 71 of the corresponding thrusters 8A, 8B, 9 to allow the PWC 1 to stay near a designated anchor position. When the automatic return control or the home position control is performed using the second propulsion device 3 of an electric type (thrusters 8A, 8B, 9) instead of the first propulsion device 2 of an engine type, the position of the PWC 1 can be accurately controlled, and the safety can be improved.

Although the use of the second propulsion device 3 of an electric type (thrusters 8A, 8B, 9) is permitted only when the engine 5 as the power source of the first propulsion device 2 is stopped in the first embodiment, the second propulsion device 3 may be used in combination with the first propulsion device 2. For example, the second propulsion device 3 may be used for achieving so-called off-throttle steering. The off-throttle steering is to change a traveling direction of the PWC 1 when the accelerator 21 is not operated. That is, when the PWC 1 is moved using the first propulsion device 2 of an engine type including the jet pump 6, the traveling direction thereof is changed by swing operation of the jet nozzle 35 that injects a jet water flow generated by the jet pump 6. Thus, particularly when the PWC 1 is moved at high speed, the traveling direction of the PWC 1 is less likely to be changed unless the jet water flow has a large flow rate to some extent. In other words, during movement of the PWC 1 using only the first propulsion device 2, the traveling direction of the PWC is less likely to be changed in a state where the accelerator 21 is turned off to reduce the amount of a jet water flow. Thus, using the second propulsion device 3 in combination is conceivable to change the traveling direction when the handle 13 is steered while the accelerator 21 is turned off. The change of the traveling direction using the second propulsion device 3 can be achieved by driving only one of the left and right longitudinal thrusters 8A, 8B or by driving the lateral thruster 9, for example.

Although the second propulsion device 3 is controlled to turn the PWC 1 clockwise (counterclockwise) when the operation lever 25 which is a joystick is tilted obliquely rightward (obliquely leftward) in the first embodiment, the second propulsion device 3 may be controlled to allow the PWC 1 to linearly travel obliquely rightward (obliquely leftward) during a similar operation. Additionally, a mode selector switch may be separately provided to appropriately select a mode of turning the PWC 1 or a mode of linearly oblique traveling of the PWC 1.

Although the operation lever 25 which is a joystick is provided as an operator for moving the PWC 1 using the second propulsion device 3 in the first embodiment, a push button, a touch panel, or the like may be provided as the operator instead of the operation lever 25.

Although the reverse bucket 7 is provided in the outlet part of the jet pump 6 to allow the PWC 1 to be moved backward using the first propulsion device 2 of an engine type in the first embodiment, the reverse bucket 7 is not essential when the PWC 1 can be moved backward using the second propulsion device 3 of an electric type. When the reverse bucket 7 is not provided, the PWC 1 is moved backward exclusively using the second propulsion device 3.

Although the entrances of the water passages 41, 42, 43 of the corresponding thrusters 8A, 8B, 9 are each formed at a position higher than the water surface S2 during planing in the first embodiment, the rear openings 41b, 42b of the corresponding water passages 41, 42 opened in a rear surface of the boat body 10 may be each formed at a position lower than the water surface S2 during planing, i.e., at a position immersed in the water.

Although the entrances of the water passages 41, 42, 43 are each formed at a position displaced in the longitudinal direction and the lateral direction from the center of gravity G of the PWC 1 in the first embodiment, the entrances of at least some of the water passages may be each formed at a position displaced only in one of the longitudinal direction and the lateral direction.

Although the longitudinal thrusters 8A, 8B that generate propulsion force in the longitudinal direction and the lateral thruster 9 that generates propulsion force in the lateral direction are prepared as the second propulsion device 3 of an electric type in the first embodiment, the longitudinal thrusters 8A, 8B or the lateral thruster 9 may not be provided. Alternatively, another thruster that generates propulsion force in a direction inclined with respect to the longitudinal direction or the lateral direction may be prepared.

Although the two longitudinal thrusters 8A, 8B are respectively attached to the left and right side parts of the boat body 10 in the first embodiment, the number of longitudinal thrusters may be one.

Although the second propulsion device 3 is of an electric type in the first embodiment, a driving method of the second propulsion device 3 is not limited to the electric type as long as the second propulsion device 3 enables the PWC 1 to be moved slowly. That is, a power source other than the electric motor may be used as the power source of the second propulsion device 3 (thrusters 8A, 8B, 9).

Although the impellers (53, 63, 73) are each used as a rotating element of the second propulsion device 3 that generates a water flow in the first embodiment, the rotating element of the second propulsion device 3 is only required to generate a water flow by rotation, and thus may be a screw or a propeller, for example. The second propulsion device 3 also may be a propulsion device of a type in which a fluid such as air or water sucked from the outside is discharged using a pump.

To use the second propulsion device of a type in which propulsion force is generated by injection of a water flow, the second propulsion device may include a water passage including an inlet and an outlet of the water flow and a power source that generates power for generating the water flow flowing through the water passage, and a specific form may be variously changed. For example, the water passage may be a branched passage in which the number of inlets is smaller than the number of outlets. In this case, the water passage may be provided in its branched part with a valve for switching a flow of the water flow to change a moving direction of the PWC 1. The number of power sources such as the electric motor may be reduced to be smaller than the number of outlets of the water passage.

Although the engine 5 of an internal combustion type is used as the power source of the first propulsion device 2 in the first embodiment, the power source of the first propulsion device 2 is not limited to the engine. As the power source of the first propulsion device, a hybrid power source in which an electric motor and an engine are combined may be used or an electric motor with high output may be used alone, for example.

Although the jet propulsion boat (PWC 1) of a riding type including the seat 14 is described as an example of the jet propulsion boat according to the present disclosure in the first embodiment, the jet propulsion boat may be of a stand-up type on which a driver rides in an upright position.

(2) SECOND EMBODIMENT

Although the impellers 53, 63, 73 of the corresponding thrusters 8A, 8B, 9 are respectively disposed in the water passages 41, 42, 43 passing through the hull 11 in the first embodiment, an arrangement destination of each of the impellers is not limited thereto. An example in which each of the impellers is disposed at a place other than the hull will be described as a second embodiment. The second embodiment includes components similar to those of the first embodiment, the components being denoted by the same reference numerals as those of the first embodiment, and duplicated description thereof will not be described. The same applies to a third embodiment described later.

FIG. 7 is a side view illustrating a jet propulsion boat 101 (hereinafter, referred to as a PWC 101) according to the second embodiment, and FIG. 8 is a partial plan sectional view of the PWC 101. As illustrated in FIGS. 7 and 8, a pair of left and right sponsons 105 are attached to a rear part of a boat body 10 of the PWC 101. The pair of sponsons 105 are each a protrusion in a plate shape protruding outward from corresponding one of left and right side surfaces of a rear part of a hull 11. Each sponson 105 has a height set to be immersed in the water when the PWC 101 is moved at low speed, and to be exposed upward from the water surface after the PWC 101 is moved at increased speed to shift to a planing state. This height prevents the sponson 105 from receiving resistance from the water during planing of the PWC 101.

The pair of sponsons 105 disposed at the height as described above has an effect of enhancing steering stability when the PWC 101 is turned. That is, during the turning of the PWC 101, only the sponson 105 inside a circle of the turning is immersed in the water to paddle the water to stabilize turning operation of the PWC 101.

As illustrated in FIG. 8, the PWC 101 of the second embodiment includes a second propulsion device 103 of an electric type including a pair of left and right longitudinal thrusters 108 in addition to a first propulsion device of an engine type (not illustrated) similar to the first propulsion device 2 shown in the first embodiment. The pair of longitudinal thrusters 108 are disposed inside the respective sponsons 105.

Specifically, the pair of sponsons 105 are each provided with a water passage 107 passing through the corresponding one of the sponsons 105 in the longitudinal direction. The water passage 107 allows a front opening 107a opened in an outer side surface of each sponson 105 to communicate with a rear opening 107b opened in a rear surface of the sponson 105. The longitudinal thruster 108 includes an electric motor 111 disposed in front of the water passage 107 inside the sponson 105, a propeller shaft 112 extending from the electric motor 111 into the water passage 107, and an impeller 113 attached to a rear end of the propeller shaft 112. The impeller 113 is rotationally driven by the electric motor 111 to generate a water flow in the longitudinal direction. Then, the generated water flow is injected from the water passage 107 to impart propulsion force in the longitudinal direction to the boat body 10. The injection direction (propulsion direction) of the water flow can be changed by forward rotation or reverse rotation of the electric motor 111.

As described above, the sponson 105 is used as an arrangement place of the longitudinal thruster 108 in the second embodiment, and thus enabling both a simple layout and steering stability during turning to be achieved. Additionally, the water flow is injected from the openings 107a, 107b formed in the sponson 105 that is a protrusion protruding outward in the width direction, and thus also bringing an advantage of easily improving operability.

Although the water passage 107 is formed to pass through the sponson 105 in the longitudinal direction in the second embodiment, the water passage 107 may be partly formed inside the boat body 10 as long as the water passage 107 includes an outlet opened in one surface of the sponson 105. The electric motor 111 and the impeller 113 may also be disposed inside the boat body 10 instead of the sponson 105.

(3) THIRD EMBODIMENT

Although all of the plurality of thrusters 8A. 8B, 9 are disposed inside the boat body 10 in the first embodiment, at least some of thrusters may be externally attached to the boat body. An example thereof will be described as a third embodiment.

FIG. 9 is a partial plan view illustrating a jet propulsion boat 201 (hereinafter, referred to as a PWC 201) according to the third embodiment of the present invention. The PWC 201 illustrated in FIG. 9 includes a second propulsion device 203 of an electric type including a pair of left and right longitudinal thrusters 208 in addition to a first propulsion device of an engine type (not illustrated) similar to the first propulsion device 2 shown in the first embodiment. The pair of longitudinal thrusters 208 are each a cylindrical thruster separate from the boat body 10, and are detachably attached to corresponding left and right side surfaces of a rear part of a hull 11 using predetermined fixing means while having respective axes extending in the longitudinal direction. The pair of longitudinal thrusters 208 are each detachable, so that each longitudinal thruster 208 can be removed when it is unnecessary.

FIG. 10 is a sectional view illustrating structure of the longitudinal thruster 208. As illustrated in FIGS. 9 and 10, the longitudinal thruster 208 includes an electric motor 211, a first propeller shaft 212 extending forward from the electric motor 211, a second propeller shaft 213 extending backward from the electric motor 211, a first impeller 214 attached to a front end of the first propeller shaft 212, a second impeller 215 attached to a rear end of the second propeller shaft 213, and a cylindrical case 216 incorporating these elements 211 to 215. The first propeller shaft 212 is connected to an output shaft of the electric motor 211 via a first clutch 218, and the second propeller shaft 213 is connected to an output shaft of the electric motor 211 via a second clutch 219.

The case 216 is a cylindrical body with opposite ends opened. That is, the case 216 has a front opening Q1 that opens forward and a rear opening Q2 that opens backward. The case 216 is partitioned in the longitudinal direction with a first partition wall 220 and a second partition wall 221 that are provided inside the case 216. The first partition wall 220 is provided between the first clutch 218 and the first impeller 214, and the second partition wall 221 is provided between the second clutch 219 and the second impeller 215. The first propeller shaft 212 passes through the first partition wall 220 in a watertight manner, and the second propeller shaft 213 passes through the second partition wall 221 in a watertight manner.

The case 216 includes a front peripheral surface in which a first water suction port P1 in an annular shape is formed. Similarly, the case 216 includes a rear peripheral surface in which a second water suction port P2 in an annular shape is formed. The first water suction port P1 is formed between the first partition wall 220 and the first impeller 214, and the second water suction port P2 is formed between the second partition wall 221 and the second impeller 215.

The longitudinal thruster 208 configured as described above is capable of rotationally driving any one of the first impeller 214 and the second impeller 215 in a selective manner using the electric motor 211, and functions as a source of forward or backward propulsion force.

For example, when the longitudinal thruster 208 generates forward propulsion force, i.e., when the PWC 201 is moved forward, the longitudinal thruster 208 is controlled as follows. That is, when the second clutch 219 is engaged and the electric motor 211 is operated in this engaged state, the second impeller 215 is rotationally driven. This rotation generates a water flow that flows into the case 216 from the second water suction port P2 and flows toward the rear opening Q2. The water flow is injected backward from the rear opening Q2, thereby generating forward propulsion force.

In contrast, when the longitudinal thruster 208 generates backward propulsion force, i.e., when the PWC 201 is moved backward, the longitudinal thruster 208 is controlled as follows. That is, when the first clutch 218 is engaged and the electric motor 211 is operated in this engaged state, the first impeller 214 is rotationally driven. This rotation generates a water flow that flows into the case 216 from the first water suction port P1 and flows toward the front opening Q1. The water flow is injected forward from the front opening Q1, thereby generating backward propulsion force.

Although not illustrated in FIG. 9, a sponson similar to the sponson 105 shown in the second embodiment also can be provided near the longitudinal thruster 208. In this case, the longitudinal thruster 208 is preferably disposed above a lower surface of the sponson. This can prevent the longitudinal thruster 208 from becoming a resistance during planing of the PWC 201.

Although the first impeller 214 for injecting a water flow forward and the second impeller 215 for injecting a water flow backward are rotationally driven using the common electric motor 211 in the third embodiment, a dedicated electric motor for rotationally driving each of the impellers 214, 215 may be individually provided.

(4) OTHERS

Although the first to third embodiments are each for a jet propulsion boat capable of planing over water using propulsion force based on a jet water flow injected from the jet pump 6, the scope of the present disclosure includes not only such a jet propulsion boat but also a propulsion boat that planes over water in an inclined posture in which a bow rises. The propulsion boat includes a first propulsion device that imparts propulsion force to a boat body, and a second propulsion device that imparts propulsion force to the boat body using a mechanism independent of the first propulsion device. The first propulsion device is only required to have a relatively high output to such an extent that the propulsion boat can be moved in a planing state. Examples of the first propulsion device include a propulsion device that imparts propulsion force to the boat body using means other than a jet pump. In other words, examples of the propulsion boat of the present disclosure include not only a jet propulsion boat but also a propeller propulsion boat. The second propulsion device has a maximum output smaller than that of the first propulsion device, and may include a mechanism similar to the second propulsion devices (3,103,203) used in the corresponding first to third embodiments described above, for example.

(5) SUMMARY

The embodiments and modifications thereof include the following disclosure.

A jet propulsion boat according to an aspect of the present disclosure includes a boat body, a first propulsion device that imparts propulsion force to the boat body by injection of a jet water flow, and a second propulsion device that imparts propulsion force to the boat body with a mechanism independent of the first propulsion device.

The present disclosure allows the jet propulsion boat to include a plurality of propulsion devices to enable operation that cannot be performed by one propulsion device, so that a degree of freedom in operation of the jet propulsion boat can be increased.

The first propulsion device is preferably a propulsion device of an engine type using an internal combustion engine as a power source, and the second propulsion device is preferably a propulsion device of an electric type using an electric motor as a power source.

This aspect enables the first propulsion device and the second propulsion device to be selectively used depending on a situation. Using the second propulsion device enables the boat body to be moved while the internal combustion engine is stopped, so that quietness can be secured.

The second propulsion device preferably includes an impeller disposed in a water passage through which water flows, and the electric motor that rotationally drives the impeller to inject a water flow from the water passage.

This aspect causes the electric motor to rotate the impeller to inject a water flow from the water passage, and thus enables propulsion force to be imparted to the boat body using the injected water flow.

The second propulsion device may include an impeller disposed in a water passage through which water flows, and a power source that rotationally drives the impeller to inject a water flow from the water passage. In this case, the water passage includes an inlet formed at a position exposed above a water surface when the jet propulsion boat is in a planing state. This aspect causes water to less likely to flow into the water passage during planing of the jet propulsion boat, and thus enables preventing the water passage from resisting the planing.

The water passage preferably has an outlet formed at a position away from the center of gravity of the jet propulsion boat in a longitudinal direction.

This aspect facilitates application of rotational moment to the boat body during turning of the jet propulsion boat.

The second propulsion device may include a longitudinal thruster that generates propulsion force for moving the boat body at least forward or backward.

This aspect enables the boat body to be moved forward or backward by using the longitudinal thruster.

The longitudinal thruster preferably includes an impeller disposed in a water passage passing through the boat body, and a power source disposed inside the boat body to rotationally drive the impeller to inject a water flow in the longitudinal direction from one end of the water passage.

This aspect enables the longitudinal thruster to be disposed inside the boat body, and thus enables preventing the longitudinal thruster from serving as resistance during movement of the boat body.

The water passage preferably includes a pair of longitudinal openings opened in the longitudinal direction at two respective positions on left and right sides across a center axis of the boat body extending in the longitudinal direction.

This aspect enables a water flow to be injected from two left and right places away from the center axis of the boat body by using each of the left and right longitudinal openings as an outlet of the water flow. This aspect facilitates adjustment of a left-right balance when the boat body is moved, and thus enables improving operability of the boat body.

The longitudinal thruster preferably includes a mechanism that causes a water flow injected from the longitudinal opening on the left side to have a flow rate that is different from a flow rate of a water flow injected from the longitudinal opening on the right side.

This aspect enables adjustment of a turning manner of the boat body by adjusting a difference between flow rates of water flows injected from the respective left and right longitudinal openings.

The power source preferably includes a first power source that generates power for injecting a water flow from the longitudinal opening on the left side, and a second power source that generates power for injecting a water flow from the longitudinal opening on the right side.

This aspect enables facilitating adjustment of a turning manner by adjusting output of the two independent power sources.

The longitudinal thruster is preferably detachably attached to the boat body.

This aspect enables the longitudinal thruster to be removed when it is unnecessary.

The second propulsion device may include a pair of longitudinal thrusters that each inject a water flow in the longitudinal direction from openings at opposite ends of corresponding one of a pair of left and right water passages extending in the longitudinal direction. In this case, each of the longitudinal thrusters preferably has a mechanism that changes a direction of a water flow flowing through the corresponding one of the water passages.

This aspect enables the boat body to be stably moved straight forward or backward by injecting a water flow backward from the openings at rear ends of the respective left and right water passages, or injecting a water flow forward from the openings at front ends of the respective left and right water passages. This aspect also enables rotating the boat body while suppressing movement of the center of gravity of the boat body by injecting a water flow forward from one of the left and right water passages and injecting a water flow backward from the other water passage.

The second propulsion device may include an impeller disposed in a water passage through which water flows, and a power source that rotationally drives the impeller. In this case, the power source is preferably capable of changing a rotation direction of the impeller.

This aspect enables injecting a water flow in a different direction from a common water passage, and thus enables expanding a range of movement that can be achieved by the boat.

The jet propulsion boat may further include a pair of left and right sponsons protruding outward from corresponding left and right side surfaces of the boat body. In this case, the second propulsion device preferably includes an impeller disposed in a water passage having an outlet in one surface of the sponson, and a power source that rotationally drives the impeller to inject a water flow from the outlet of the water passage.

This aspect enables enhancing operability by injecting a water flow from one surface of the sponson that is a protrusion protruding outward in the width direction.

The second propulsion device may include a lateral thruster that generates propulsion force for moving the boat body at least leftward or rightward.

This aspect enables the boat body to be moved leftward or rightward by using the lateral thruster.

The lateral thruster preferably includes an impeller disposed in a water passage passing through the boat body, and a power source provided inside the boat body to rotationally drive the impeller to inject a water flow in a lateral direction from one end of the water passage.

This aspect enables the lateral thruster to be disposed inside the boat body, and thus enables preventing the lateral thruster from serving as resistance during movement of the boat body.

The second propulsion device may be capable of generating propulsion force for moving the boat body in the longitudinal direction and propulsion force for moving the boat body in the lateral direction.

This aspect enables the boat body to be freely moved in the longitudinal direction and the lateral direction.

The second propulsion device preferably includes a pair of left and right longitudinal thrusters that each generate propulsion force for moving the boat body at least forward or backward, and a lateral thruster that generates propulsion force for moving the boat body at least leftward or rightward.

This aspect enables the boat body to be appropriately moved forward, backward, left, and right, by using the pair of longitudinal thrusters and the lateral thruster in combination.

The pair of longitudinal thrusters are preferably disposed on the respective left and right sides of a rear part of the boat body in a posture in which an injection axis of a water flow faces the longitudinal direction, and the lateral thruster is preferably disposed in a front part of the boat body in a posture in which an injection axis of a water flow faces the lateral direction.

This aspect enables the pair of longitudinal thrusters and the lateral thruster to be disposed at respective places of the boat body in a well-balanced manner.

A propulsion boat according to another aspect of the present disclosure which planes on water in an inclined posture in which a bow rises, the propulsion boat including a boat body, a first propulsion device that imparts propulsion force to the boat body, the propulsion force capable of moving the propulsion boat in a planing state, and a second propulsion device that imparts propulsion force to the boat body with a mechanism independent of the first propulsion device. The second propulsion device includes an impeller disposed in a water passage through which water flows, and a power source that rotationally drives the impeller to inject a water flow from the water passage. The water passage includes an entrance formed at a position exposed above from a water surface when the propulsion boat is in a planing state.

The present disclosure causes water to less likely to flow into the entrance of the water passage during planing of the propulsion boat, and thus enables preventing the water passage from resisting the planing, thereby enabling smooth planing.

Claims

1. A jet propulsion boat comprising:

a boat body;
a first propulsion device that imparts propulsion force to the boat body by injection of a jet water flow; and
a second propulsion device that imparts propulsion force to the boat body with a mechanism independent of the first propulsion device.

2. The jet propulsion boat according to claim 1, wherein

the first propulsion device is a propulsion device of an engine type using an internal combustion engine as a power source, and
the second propulsion device is a propulsion device of an electric type using an electric motor as a power source.

3. The jet propulsion boat according to claim 2, wherein

the second propulsion device includes an impeller disposed in a water passage through which water flows, and the electric motor that rotationally drives the impeller to inject a water flow from the water passage.

4. The jet propulsion boat according to claim 1, wherein

the second propulsion device includes an impeller disposed in a water passage through which water flows, and a power source that rotationally drives the impeller to inject a water flow from the water passage, and
the water passage includes an inlet formed at a position exposed above a water surface when the jet propulsion boat is in a planing state.

5. The jet propulsion boat according to claim 3, wherein

the water passage includes an outlet formed at a position away from a center of gravity of the jet propulsion boat in a longitudinal direction.

6. The jet propulsion boat according to claim 1, wherein

the second propulsion device includes a longitudinal thruster that generates propulsion force for moving the boat body at least forward or backward.

7. The jet propulsion boat according to claim 6, wherein

the longitudinal thruster includes an impeller disposed in a water passage passing through the boat body, and a power source disposed inside the boat body to rotationally drive the impeller to inject a water flow in the longitudinal direction from one end of the water passage.

8. The jet propulsion boat according to claim 7, wherein

the water passage includes a pair of longitudinal openings opened in the longitudinal direction at two respective positions on left and right sides across a center axis of the boat body extending in the longitudinal direction.

9. The jet propulsion boat according to claim 8, wherein

the longitudinal thruster includes a mechanism that causes a water flow injected from the longitudinal opening on the left side to have a flow rate that is different from a flow rate of a water flow injected from the longitudinal opening on the right side.

10. The jet propulsion boat according to claim 9, wherein

the power source includes a first power source that generates power for injecting a water flow from the longitudinal opening on the left side, and a second power source that generates power for injecting a water flow from the longitudinal opening on the right side.

11. The jet propulsion boat according to claim 6, wherein

the longitudinal thruster is detachably attached to the boat body.

12. The jet propulsion boat according to claim 1, wherein

the second propulsion device includes a pair of longitudinal thrusters that each inject a water flow in the longitudinal direction from openings at opposite ends of corresponding one of a pair of left and right water passages extending in the longitudinal direction, and
each of the longitudinal thrusters has a mechanism that changes a direction of a water flow flowing through the corresponding one of the water passages.

13. The jet propulsion boat according to claim 1, wherein

the second propulsion device includes an impeller disposed in a water passage through which water flows, and a power source that rotationally drives the impeller, and
the power source is capable of changing a rotation direction of the impeller.

14. The jet propulsion boat according to claim 1, further comprising:

a pair of left and right sponsons protruding outward from corresponding left and right side surfaces of the boat body,
wherein the second propulsion device includes an impeller disposed in a water passage having an outlet in one surface of each of the sponsons, and a power source that rotationally drives the impeller to inject a water flow from the outlet of the water passage.

15. The jet propulsion boat according to claim 1, wherein

the second propulsion device includes a lateral thruster that generates propulsion force for moving the boat body at least leftward or rightward.

16. The jet propulsion boat according to claim 15, wherein

the lateral thruster includes an impeller disposed in a water passage passing through the boat body, and a power source provided inside the boat body to rotationally drive the impeller to inject a water flow in a lateral direction from one end of the water passage.

17. The jet propulsion boat according to claim 1, wherein

the second propulsion device is capable of generating propulsion force for moving the boat body in the longitudinal direction and propulsion force for moving the boat body in the lateral direction.

18. The jet propulsion boat according to claim 17, wherein

the second propulsion device includes a pair of left and right longitudinal thrusters that each generate propulsion force for moving the boat body at least forward or backward, and a lateral thruster that generates propulsion force for moving the boat body at least leftward or rightward.

19. The jet propulsion boat according to claim 18, wherein

the pair of longitudinal thrusters are disposed on the respective left and right sides of a rear part of the boat body in a posture in which an injection axis of a water flow faces the longitudinal direction, and
the lateral thruster is disposed in a front part of the boat body in a posture in which an injection axis of a water flow faces the lateral direction.

20. A propulsion boat which planes on water in an inclined posture in which a bow rises, the propulsion boat comprising:

a boat body;
a first propulsion device that imparts propulsion force to the boat body, the propulsion force capable of moving the propulsion boat in a planing state; and
a second propulsion device that imparts propulsion force to the boat body with a mechanism independent of the first propulsion device,
wherein the second propulsion device includes an impeller disposed in a water passage through which water flows, and a power source that rotationally drives the impeller to inject a water flow from the water passage, and
the water passage includes an entrance formed at a position exposed above from a water surface when the propulsion boat is in a planing state.
Patent History
Publication number: 20240278891
Type: Application
Filed: Feb 17, 2023
Publication Date: Aug 22, 2024
Applicant: KAWASAKI MOTORS, LTD. (Hyogo)
Inventors: Toshio ARAKI (Akashi-shi), Kazumasa HISADA (Akashi-shi), Daisuke KAWAI (Kobe-shi), Shohei TERAI (Kobe-shi), Takuya SAKAMOTO (Akashi-shi), Yoshihito UCHINO (Akashi-shi)
Application Number: 18/110,899
Classifications
International Classification: B63H 11/08 (20060101); B63H 25/46 (20060101);