Drive system for a marine vessel

Abstract

A drive system for a marine vessel. The drive system includes a drive shaft that is rotatable about a drive axis and a motor interconnected with the drive shaft and including a rotor that defines a motor axis that is substantially coaxial with the drive axis. The motor is operable at a motor speed to rotate the drive shaft. An engine has an output shaft interconnected with the drive shaft and is operable at an engine speed to rotate the drive shaft. The output shaft defines an engine axis that is substantially coaxial with the motor axis. A clutch is operable to inhibit the transfer of torque from the motor to the engine when the engine speed is less than a predetermined engine speed without disconnecting the output shaft from the drive shaft. A tiller arm includes a speed control. The speed control is operable to control the engine speed and to control the motor speed.

Description

BACKGROUND

The present invention relates generally to a drive system for a marine vessel. More particularly, the present invention relates to a hybrid drive system for a marine vessel.

Marine vessels (e.g., boats, inflatable rafts, canoes, sailboats, personal watercraft, and the like) generally include an engine that turns a propeller to propel the vessel through the water. Generally, the engine is an internal combustion engine that combusts fuel to propel the vessel. Many boats employ an outboard engine, which mounts to the transom of the vessel and extends into the water. The engine turns the propeller in the water to generate propulsion. Other vessels may employ inboard engines in which the engine is disposed within the boat and only a portion of a driveshaft and the propeller extend into the water. Still other vessels use an inboard-outboard engine, which combines certain aspects of inboards and outboards. Generally, the engine is disposed within the boat and a lower unit containing a drive shaft and various gears is disposed outside the boat.

While engines are well-suited to propelling vessels in the water, there are restrictions on the use of engines on some bodies of water. In addition, sportsmen often use an electric motor to quietly move their vessel into a fishing or hunting area. Unfortunately, these electric motors are separate from the main engine, thus requiring their own control system as well as their own mechanical systems (e.g., lower unit extending into the water, propeller, driveshaft, drive gears, and the like). In addition, the electric motors are often visually unappealing and provide additional obstructions for fishing and occupy additional space within the vessel.

SUMMARY

The present invention provides a drive system for a marine vessel. The drive system includes a drive shaft that is rotatable about a drive axis, and an electric motor interconnected with the drive shaft and including a rotor that defines a motor axis that is substantially coaxial with the drive axis. The motor is operable at a motor speed to rotate the drive shaft. An engine has an output shaft interconnected with the drive shaft and is operable at an engine speed to rotate the drive shaft. The output shaft defines an engine axis that is substantially coaxial with the motor axis. A clutch is operable to inhibit the transfer of torque from the motor to the engine when the engine speed is less than a predetermined engine speed without disconnecting the output shaft from the drive shaft. A tiller arm includes a speed control. The speed control is operable to control the engine speed and to control the motor speed.

In another aspect, the invention provides a drive system for a marine vessel. The drive system includes a drive shaft that is rotatable about a drive axis to propel the vessel, and a motor that includes a rotor coupled to the drive shaft. The motor is operable at a motor speed to rotate the drive shaft. An engine that includes an engine ignition is coupled to the motor rotor and is operable at an engine speed to rotate the rotor and the drive shaft. The drive system also includes an electrochemical energy source (e.g., a battery or fuel cell) and a controller that is operable to control the flow of electrical power between the electrochemical energy source and the motor. A clutch is disposed between the motor rotor and the engine. The clutch has a declutched position in which the transfer of torque from the motor to the engine is inhibited without decoupling the engine and the motor rotor. A switch has a first position in which the engine is operable and a second position which inhibits operation of the engine but enables the motor to be operable. The drive system also includes a tiller arm having a speed control. The speed control is operable to control the engine speed when the switch is in the first position and to control the motor speed when the switch is in the second position. A switch has a first position in which the engine is operable, and a second position in which the engine ignition is grounded but the motor is operable.

In still another aspect, the present invention provides a drive system for a marine vessel. The drive system includes a drive shaft that is rotatable about a drive axis. A motor includes a stator and a rotor that defines a motor axis. The rotor is offset from the stator a distance along the motor axis to define an axial air gap. The drive shaft rotates in response to rotation of the rotor at a motor speed. An engine includes an output shaft. The drive shaft and rotor rotate in response to operation of the engine at an engine speed. A clutch is operable to inhibit the transfer of torque from the motor to the engine and to facilitate the transfer of torque from the engine to the motor and to the drive shaft without manipulating any mechanical connection between the motor, the engine, and the drive shaft.

Additional features and advantages will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figures in which:

FIG. 1 is a perspective view of a marine vessel with a hybrid outboard motor;

FIG. 2 is a partially broken away schematic view of the hybrid outboard motor of FIG. 1;

FIG. 3 is an enlarged schematic view of a portion of the hybrid outboard motor of FIG. 1;

FIG. 4 is a perspective view of a one-way bearing;

FIG. 5 is a top view of a centrifugal clutch;

FIG. 6 is an enlarged schematic illustration of the motor portion of FIG. 1 including a centrifugal clutch;

FIG. 7 is an enlarged schematic illustration of the motor portion of FIG. 1 including a one-way bearing;

FIG. 7a is an enlarged schematic illustration of the motor portion of FIG. 1 including another arrangement of the one-way bearing;

FIG. 8 is a schematic diagram of a control system for the hybrid motor of FIG. 1;

FIG. 9 is schematic diagram of another control system for the hybrid motor of FIG. 1; and

FIG. 10 is a schematic diagram of another control system for the hybrid motor of FIG. 1.

Before any embodiments of the invention are explained, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof is meant to encompass the items listed thereafter and equivalence thereof as well as additional items. The terms “connected,” “coupled,” and “mounted” and variations thereof are used broadly and encompass direct and indirect connections, couplings, and mountings.

DETAILED DESCRIPTION

With reference to FIG. 1, a marine vessel 10, in the form of a boat, is illustrated as including an outboard engine 15. Vessels 10 of this type are often used on small lakes and streams for fishing or other activities. The outboard engine 15 provides power to move the marine vessel 10 and rotates about a steering axis to steer the vessel 10. While the present invention will be described in detail as it applies to an outboard engine 15 similar to that of FIG. 1, one of ordinary skill will realize that the invention has other applications. For example, other types of boats or vessels (e.g., canoes, sailboats, runabouts, personal watercraft, etc.) could employ the present invention. Furthermore, the present invention could be used with an inboard engine or an inboard-outboard engine. As such, the description of the invention as it applies to an outboard engine 15 should not be read as limiting the invention to only outboard engines 15.

Turning to FIG. 2, the outboard engine 15 of FIG. 1 is shown schematically with a portion of an exterior housing 20 broken away to show the internal components. The engine 15 includes an upper portion 25 that houses two prime movers, and a lower unit 30 that supports a propeller 35 and contains forward/reverse gearing 40 and a portion of a drive shaft 45. The lower unit 30 extends below the water line 50 to allow rotation of the propeller 35 to propel the vessel 10.

The prime movers disposed in the upper portion 25 of the engine are best shown in FIG. 3 and include an internal combustion engine 55 and an electric motor 60. The electric motor 60 is positioned beneath the internal combustion engine 55 and is interconnected with the drive shaft 45. The internal combustion engine 55 also interconnects with the drive shaft 45. Thus, operation of the electric motor 60 or the internal combustion engine 55 can produce rotation of the drive shaft 45 and propeller to propel the vessel 10. In most constructions, the internal combustion engine 55 is air-cooled. However, some constructions may employ a water-cooled engine. Water is drawn from the body of water the vessel is operating on and is directed up the lower unit 30 to the engine. After cooling the engine, the water returns down the lower unit 30 and flows back into the body of water.

The electric motor 60, shown in FIG. 3, is a brushless DC axial air gap motor that includes a stator 65 and a rotor 70, and may include a motor controller 75 (shown in FIG. 9). A motor 60 of this type is sold by Briggs & Stratton Corporation of Milwaukee, Wis. under the trademark ETEK. While other types of motors could be employed, the motor 60 described herein occupies a compact space and provides the horsepower and torque desired to propel the vessel 10 through the water.

The stator 65 fixedly attaches to the exterior housing 20 of the outboard engine 15 such that it is substantially coaxial with the drive shaft 45. The stator 65 includes a plurality of poles that each include windings that can be selectively energized to produce the necessary magnetic fields for motor operation. The stator 65 also includes a substantially cylindrical opening 80 through its center that allows for the passage of a motor shaft, if employed, or the drive shaft 45.

The rotor 70 is a substantially disk-shaped component that supports a plurality of permanent magnets 85. The rotor 70 is supported above the stator 65 with the permanent magnets 85 axially spaced from the stator windings such that as the stator windings are energized, a magnetic field is produced that interacts with the permanent magnets 85 of the rotor 70 to produce rotation. The stator windings are energized and de-energized in a particular sequence, at a particular rate, and with a particular polarity to produce rotation of the rotor 70 in a desired direction at a desired speed.

In most constructions, a thrust bearing 90 is disposed between the rotor 70 and the stator 65 to both position the rotor 70 relative to the stator 65 and to support the axial load (the weight) of the rotor 70 during motor operation. FIGS. 3, 6, and 7 schematically illustrate a thrust bearing 90 that is suited to the task of supporting the rotor 70. Other constructions may apply other suitable means to separate the rotor 70 from the stator 65. For example, one or more bearings generally support the drive shaft 45 for rotation. One of these bearings could include thrust-carrying capability such that the bearing supports the thrust load of the rotor 70. In these constructions, the drive shaft 45 supports the generator rotor 70 in the desired axial position without the need for a separate thrust bearing 90 between the rotor 70 and the stator 65.

The internal combustion engine 55, illustrated in FIG. 3, includes a housing 95 that supports one or more piston/cylinder arrangements that operate to rotate a crankshaft, as is well known in the engine art. The number of piston/cylinder arrangements employed is largely a function of the power required for the particular application. The engine 55 combusts an air/fuel mixture to rotate the crankshaft and produce shaft power. The crankshaft extends from the housing to define an output shaft 100. In most constructions, the output shaft 100 extends vertically from the bottom of the housing 95 along an engine axis A-A. The engine 55 is similar to known internal combustion engines and as such will not be described in detail.

Support members 103 engage the engine 55 and the exterior housing 20 to support the engine 55 in its desired operating position above the electric motor 60. As illustrated in FIGS. 2 and 3, the support members 103 resemble columns. The actual form of the support members 103 is unimportant so long as they are capable of supporting the engine 55 above the motor 60. The support members generally provide no alignment function but rather allow the engine 55 to move as needed to properly align the output shaft 100 relative to the drive shaft 45. For example, in one construction a platform is supported by the stator 65 and is shaped to support the engine 55.

The output shaft 100 extends from the bottom of the engine 55 and engages a clutch mechanism 105 between the engine 55 and motor 60. FIGS. 2, 3, 5 and 6 illustrate one possible clutch mechanism 105 in the form of a centrifugal clutch 110. The centrifugal clutch 110 includes an outer drum 115, a biasing member 120 (e.g., one or more springs), and a plurality of clutch weights 125. A pocket 130, including cylindrical walls, is formed in the motor rotor 70 to define the outer drum 115. Forming the outer drum 115 in the motor rotor 70 provides for a more compact arrangement, while simultaneously reducing the number of components. The clutch weights 125 are disposed within the drum 115 and are fixedly attached to the output shaft 100 so that they rotate in unison with the shaft 100 but are free to move radially. The clutch weights 125 move radially between a disengaged (declutched) position and an engaged (clutched) position within the pocket 130, with the biasing member 120 biasing the clutch weights 125 toward the disengaged position.

The biasing member 120 is sized to produce a biasing force that is substantially equal to the centrifugal force applied to the clutch weights 125 at a predetermined rotational speed. In some constructions, this predetermined rotational speed is slightly above the idle speed of the engine 55 such that when the engine 55 idles, the clutch 110 disengages to produce a neutral operating condition. Of course other constructions may allow clutch engagement at lower or higher speeds as required by the particular application. As the engine 55 accelerates, the rotational speed exceeds the predetermined speed and the centrifugal force applied to the weights 125 exceeds the force of the biasing members 120. Once the centrifugal force exceeds the biasing force, the clutch weights 125 move to the clutched position. In the clutched position, the clutch weights 125 frictionally engage the drum 115, or pocket 130, such that the output shaft 100 and the drum 115 (i.e., the rotor 70) rotate in unison.

During electric motor operation, the motor rotor 70, and the pocket 130 rotate around the clutch weights 125. However, because the output shaft 100 does not rotate, no forces are applied to the clutch weights 125. As such, the clutch weights 125 cannot engage the cylindrical surface of the pocket 130 and instead remain in the disengaged or declutched position. Thus, the electric motor 60 does not transfer torque to the internal combustion engine 55 when the motor rotor 70 is rotating and the output shaft 100 is stopped or is rotating too slowly to overcome the biasing force produced by the biasing member 120. The centrifugal clutch 110 allows the engine 55 to rotate both the propeller 35 and the motor rotor 70 when the engine 55 is powering the vessel 10 and inhibits rotation of the engine 55 when the motor 60 is providing power to the propeller 35.

FIGS. 4, 7, and 7a illustrate another possible clutch mechanism 105 that is suited for use with the present engine 15. The clutch mechanism 105, in the form of a one-way bearing 135 (shown in detail in FIG. 4), is illustrated in FIGS. 7 and 7a in two possible operating positions. The one-way bearing 135 includes an outer race 140, an inner cage 145, and a plurality of rolling members 150. As illustrated in FIG. 7, the outer race 140 engages the output shaft 100, while the rolling members 150 engage a stub shaft 155 that is coupled to the motor rotor 70. During operating conditions in which the stub shaft 155 rotates at a higher speed than the output shaft 100, the rolling members 150 move into a free rolling position. In the free rolling position, the rolling members 150 allow relative movement between the stub shaft 155 and the output shaft 100. If, on the other hand, the output shaft 100 rotates at a higher speed than the stub shaft 155, the rolling members 150 move into a locked position. With the rolling members 150 in the locked position, the stub shaft 155 and the output shaft 100 rotate in unison. Thus, the bearing 135 allows torque transfer from the engine 55 to the motor rotor 60 when the output shaft 100 rotates faster than the motor rotor 60. However, the bearing 135 inhibits torque transfer from the motor rotor 70 to the engine 55 when the motor rotor 70 is rotating at a higher speed than the output shaft 100.

It should be noted that FIG. 7 illustrates a construction in which the outer race 140 of the one-way bearing 135 engages the output shaft 100 and the stub shaft 155 engages the rolling members 150. One of ordinary skill will realize that this arrangement could be reversed such that the rolling members 150 engage the output shaft 100 and the outer race 140 engages the stub shaft 155.

FIG. 7a illustrates another construction in which the stub shaft 155 is eliminated. In this construction, the outer race 140 of the one-way bearing 135 engages a bearing pocket 160 formed in the motor rotor 70 and the engine output shaft 100 engages the rolling members 150 within the bearing 135. This construction has the advantage of reducing the quantity of components needed and further reduces the space occupied by the engine 55 and motor 60.

While bearings 135 of the type described are available from many sources, one such one-way bearing 135 suited for use with the present engine 15 is sold by The Timken Company, located in Canton Ohio, as Timken Torrington Drawn Cup Roller Clutch bearings.

As illustrated in FIG. 3, the drive shaft 45 extends the full length of the lower unit 30 and engages the rotor 70. Of course, other constructions may include two or more shafts that are directly coupled to one another or indirectly connected (e.g., via a belt, a chain, a gear, a transmission, and the like). When two or more shafts are employed, a motor shaft (not shown) engages the rotor 70 such that rotation of the rotor 70 produces a corresponding rotation of the motor shaft and the drive shaft 45, which is coupled to the motor shaft. Connection of the motor shaft to the rotor 70 may be achieved using many common connections, including but not limited to, a spline connection or a keyed connection. Splined and keyed connections provide excellent rotational coupling, while still allowing for some relative axial movement between the motor shaft and the rotor 70. Thus, exact axial positioning of the rotor 70 relative to the motor shaft or propeller 35 is not necessary.

While a direct drive system has been described (i.e., the drive shaft 45 rotates at the same speed as the engine 55 or motor 60), certain applications may employ a transmission disposed between the internal combustion engine 55 and/or the motor 60 and the drive shaft 45. The transmission may simply allow the engine 55 or motor 60 to be offset relative to the drive shaft 45 without changing the rotational speed of the drive shaft 45 or may include a speed-reducer or a speed-increaser. For example, it may be desirable to rotate the propeller 35 at a speed that is substantially faster or substantially slower than the optimal engine or motor speed. In these applications, a speed-increaser or a speed-reducer could be positioned between the engine 55 and/or motor 60 and the propeller 35 to achieve the desired results.

The use of the clutch mechanism 105 as described allows the user to switch between engine operation and motor operation without disturbing any mechanical connections. Thus, the user is not required to make any mechanical adjustments such as shifting between gears, engaging the motor 60 with a drive gear, or disengaging the engine output shaft 100 and the drive shaft 45. Rather, the user moves an electrical switch 170 (shown in FIGS. 8 and 9) to transition between the engine 55 and the motor 60. The motor rotor 70, the engine output shaft 100, and the drive shaft 45 remain coupled during all operating modes.

Both the engine 55 and the motor 60 include separate speed input systems that allow the user to control the speed of the vessel 10 using a common interface. To control the speed of the vessel 10 when operating under engine power, the user adjusts the throttle position as is well known in the engine art. The outboard engine 15 includes a tiller arm 175 (shown in FIGS. 1 and 2) that has a rotatable handle 180 positioned at one end. The rotatable handle 180 is coupled to a throttle cable such that rotation of the handle 180 changes the throttle position and varies the speed of the engine 55. In other constructions, rotation of the handle 180 produces axial movement of a throttle cable. The throttle cable is threaded through the engine 55 and housing 95 to the carburetor throttle control such that the motion of the throttle cable directly adjusts the throttle position. Typically, the rotatable handle 180 is biased to a low speed or idle position, thereby requiring the operator to rotate and hold the handle 180 in a particular position to maintain the speed of the engine 55 above an idle speed.

When operating under motor power, the user controls the speed of the electric motor 60 and not the engine 55. Rather than provide a separate interface, the present invention provides a sensor 185 coupled to the rotatable handle 180 of the tiller arm 175. The sensor 185 may be integrated with the throttle control such that rotation of the handle 180 not only adjusts the throttle position but also adjusts the sensor 185. For example, a rotary potentiometer could be positioned such that the movement of the throttle cable produces a corresponding movement of the potentiometer. Rotation of the handle 180 would vary the resistance of the potentiometer (e.g., between 0 and 500 Ohms). The variable resistance is sensed by the controller 75 and is used as a speed set point, or is used directly to vary the current provided to the motor 60. For example, a zero Ohm resistance may be representative of a maximum speed. Thus, when the potentiometer is rotated to the zero Ohm position, the controller 75 drives the motor 60 to its highest rotational speed. Similarly, 500 Ohms may be representative of zero speed. Thus, when the controller 75 senses 500 Ohms (or more) of resistance from the potentiometer, the speed of the motor 60 is reduced to a minimum value (zero RPM). In this manner, rotation of the rotatable handle 180 produces a speed control signal that the motor controller 75 can use to control the speed of the motor 60 when the motor 60 is powering the vessel 10.

One of ordinary skill will realize that other devices could be used in place of the potentiometer. For example, linear or rotary variable differential transformers are also well suited to the task of indicating a desired speed. As such, the present invention should not be limited to rotary potentiometers or potentiometers for that matter.

One possible control system suited to powering and controlling the electric motor 60 is illustrated in FIG. 8. The control system includes the switch 170, a relay or contactor 190, the sensor 185, and an electrochemical energy source in the form of a battery 195. The switch 170 is generally a double pole switch movable between a “gas” position and an “electric” position. A first circuit 200 includes the switch 170, a pair of wires, and a portion of the engine ignition system. The circuit 200 is controlled by the switch 170 extends from the engine 55 and, when closed, grounds the ignition system of the engine 55 to inhibit engine operation. A second circuit 205 also includes the switch 170, the contactor 190, and the battery 195. The second circuit 205 is controlled by the switch 170 and powers the relay 190 that opens and closes a contact between the battery 195 and the motor 60. With the switch 170 in the position illustrated in FIG. 8, the ignition system is not grounded and is able to provide power to the engine's spark plug. In addition, the relay circuit is open such that the power circuit, controlled by the relay 190, remains open and battery power cannot travel to the motor 60. Thus, the illustrated configuration would allow engine operation and inhibit motor operation.

When the switch 170 is moved to the electric position, both the relay circuit 205 and the engine ignition system circuit 200 close. With the switch 170 in the closed position, the engine ignition system is grounded and cannot deliver power to the spark plugs. Thus, the engine 55 will not operate. In addition, the closed relay circuit 205 energizes the relay 190 to close the contact between the battery 195 and the motor 60. Thus, power is free to travel from the battery 195 to the motor 60 and the motor 60 is able to propel the vessel 10. The sensor 185, (i.e., the potentiometer) is positioned in the circuit between the motor 60 and the battery 195 to allow the potentiometer to control the power flow to the motor 60 and to vary the speed of the motor 60. As discussed, the potentiometer is connected to the rotatable handle 180 of the tiller arm 175 so that a user may rotate the handle 180 to vary the resistance of the circuit and the speed of the motor 60.

In another construction illustrated in FIG. 10, the sensor 185 includes a rotary switch rather than a potentiometer. Rotation of the rotatable handle 180 of the tiller arm 175 opens or closes the rotary switch. When the rotary switch is closed, the motor 60 rotates at a fixed speed and when the switch is open, the motor 60 does not rotate. Thus, the user is able to control the speed of the vessel 10 when propelled by the motor 60 by rotating the same handle 180 that is rotated when powered by the internal combustion engine 55.

FIG. 9 illustrates another control system suited for use with the present invention. The control system includes the switch 170, the sensor 185, the motor controller 75, and the electrochemical energy source in the form of the battery 195. Many different motor controllers 75 can be used to control the motor 60. In addition, because many different types of motors 60 can be used (e.g., brush-type DC motors, brushless DC motors, and the like), different types of controllers 75 may be employed. For example, a set of switches and contactors could be used if the motor 60 is a brush-type DC motor. If the motor 60 is a brushless DC motor, a MOSFET-based brushless DC motor control would be well-suited to controlling the motor 60.

The switch 170 is generally a double pole switch that controls two separate circuits. A first, or engine ignition circuit 210, is open when the switch 170 is in the “gas” position and is closed when the switch 170 is moved to the “electric” position. The ignition circuit 210 includes the switch 170, a pair of wires, and a portion of the engine ignition system. When the engine ignition circuit 210 is closed, the ignition system of the engine 55 is grounded and no electrical power can be delivered to the spark plug(s) of the engine 55. Thus, engine operation is inhibited. A second circuit 215 includes the switch 170, and a portion of the controller 75. The second circuit 215 sends a control signal to the motor controller 75. When the switch 170 is in the “gas” position, a signal is sent to the motor controller 75 that allows the motor controller 75 to function as a power conditioner or regulator such that electricity generated by the engine driven motor 60 can be used to charge the battery 195. When the switch 170 is in the “electric” position, a signal is sent to the controller 75 that indicates that the controller 75 is controlling the motor 60.

In other constructions, the second circuit 205 controls a relay as was described with regard to FIG. 8. In these constructions, the motor 60 does not charge the battery 195 when operating under engine power. In still other constructions, the second circuit 205 is eliminated and the controller 75 automatically determines if it should be regulating power for delivery to the battery 195 or delivering power to the motor 60 to propel the vessel 10.

When operating under motor power, the controller 75 receives a flow of DC current from the battery 195. The controller 75 in turn delivers power to the electric motor 60 via two of three power connections between the controller 75 and the motor 60. Each of the power connections provides power to a distinct winding within the stator 65. The power provided by the controller 75 is provided to the particular windings in a particular order, at a particular rate, and with a particular polarity to produce a rotating magnet field within the stator 65. The permanent magnets 85 of the rotor 70 react to the rotating magnetic field by rotating. Thus, by controlling the rate at which the rotating magnetic field rotates, the controller 75 is able to control the rotary speed of the motor 60.

One or more Hall devices or Hall sensors 220 are positioned adjacent the rotor 70 to sense the actual rotary position of the rotor 70. The Hall sensors 220 send signals to the controller 75 indicating the actual position of the rotor 70 to allow the controller 75 to refine the control of the motor 60 and accurately maintain the desired rotor speed.

As discussed, the motor controller 75 can also function as a voltage regulator to charge the battery 195 when the internal combustion engine 55 is operating and the motor 60 is idle. When operating under engine 55 power, the internal combustion engine rotates the rotor 70 without current being provided to the stator windings. The permanent magnets 85 on the rotor 70 induce an electrical current in the windings that flows to the controller 75. The controller 75 conditions the power such that it can be delivered to the battery 195 to charge the battery 195.

In use, either the internal combustion engine 55 or the electric motor 60 can power the vessel 10. In one mode, a user employs the internal combustion engine 55 to move the vessel 10 toward a desired location. To use the internal combustion engine 55, the switch 170 is positioned in the fuel position and the engine 55 is started. Once started, the internal combustion engine 55 provides power to the propeller 35 and rotates the motor rotor 70 to charge the battery 195. As the user approaches the desired location, the internal combustion engine 55 can be shut off and the switch 170 can be moved to the electric position. In the electric position, the switch 170 grounds the engine's ignition to inhibit the combustion process. In addition, the controller 75 provides power to the electric motor 60, thereby allowing the motor 60 to propel the vessel 10. The clutch mechanism 105 inhibits rotation of the engine 55 as the electric motor 60 moves the vessel 10 around the desired location.

In the application just described, the electric motor 60 would generally be smaller (output less power) than the internal combustion engine 55. For example, a twenty horsepower internal combustion engine may be used with a five horsepower motor. In other applications, equal power internal combustion engines and electric motors are used. In still other applications, large electric motors are used with relatively small internal combustion engines.

The present invention can be manufactured as a single unit or as components that can be applied to pre-existing outboard motors. When manufactured as components, the electric motor 60 and controller 75 are generally provided for attachment to a pre-existing internal combustion engine, such as illustrated engine 55. The engine 55 is decoupled from the drive shaft 45 and removed. The electric motor 60 is placed in the position previously occupied by the engine 55 and the motor 60 is coupled to the drive shaft 45. The support members 103 are positioned as necessary to support the engine 55 above the motor 60. The engine 55 is repositioned above the motor 60 and the engine output shaft 100 is coupled, via the clutch mechanism 105, to the motor rotor 70. In this way, an internal combustion engine is converted to a hybrid combustion-electric propulsion system.

Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.

Claims

1. A drive system for a marine vessel, the drive system comprising:

a drive shaft rotatable about a drive axis;

a motor including a rotor that defines a motor axis, the drive shaft rotating in response to rotation of the rotor at a motor speed;

an engine including an output shaft, the drive shaft and rotor rotating in response to operation of the engine at an engine speed;

a clutch operable to inhibit the transfer of torque from the motor to the engine and to facilitate the transfer of torque from the engine to the motor and to the drive shaft without manipulating any mechanical connection between the motor, the engine, and the drive shaft; and

a tiller arm including a speed control, the speed control operable to control the engine speed and to control the motor speed.

2. The drive system of claim 1, wherein the motor includes a stator, and wherein the rotor is spaced axially from the stator to define an axial air gap.

3. The drive system of claim 1, wherein the motor rotor is interconnected with the drive shaft such that the motor rotor rotates in unison with the drive shaft.

4. The drive system of claim 1, wherein the clutch connects the output shaft and the motor rotor.

5. The drive system of claim 1, wherein the clutch includes a clutched position and a declutched position and wherein the clutch is in the declutched position when the engine speed is below a predetermined speed and is in the clutched position when the engine speed is above the predetermined speed.

6. The drive system of claim 1, wherein the clutch includes a centrifugal clutch.

7. The drive system of claim 1, wherein the clutch includes a roller clutch.

8. The drive system of claim 1, wherein at least a portion of the clutch is formed as part of the rotor.

9. The drive system of claim 1, further comprising a switch having a first position in which the engine is operable, and having a second position in which operation of the engine is inhibited but the motor is operable.

10. The drive system of claim 9, wherein the engine includes an engine ignition that is grounded when the switch is in the second position.

11. The drive system of claim 9, wherein the engine operates when the switch is in the first position to rotate the motor rotor and the drive shaft, the rotation of the motor rotor delivering a flow of electrical current to an electrochemical energy source, and wherein when the switch is in the second position the electrochemical energy source delivers a flow of electrical current to the motor such that the motor operates to rotate the drive shaft.

12. The drive system of claim 9, wherein the speed control is operable to control the engine speed when the switch is in the first position and to control the motor speed when the switch is in the second position.

13. The drive system of claim 9, further comprising a power conditioner interconnecting the motor and an electrochemical energy source, the power conditioner operable to deliver conditioned power to the electrochemical energy source when the switch is in the first position and to deliver an amount of conditioned power to the motor when the switch is in the second position.

14. The drive system of claim 1, wherein the speed control includes a potentiometer.

15. A drive system for a marine vessel, the drive system comprising:

a drive shaft rotatable about a drive axis to propel the vessel;

a motor including a rotor coupled to the drive shaft, the motor operable at a motor speed to rotate the drive shaft;

an engine including an engine ignition, the engine coupled to the motor rotor and operable at an engine speed to rotate the rotor and the drive shaft;

an electrochemical energy source;

a controller operable to control the flow of electrical power between the electrochemical energy source and the motor;

a clutch disposed between the motor rotor and the engine, the clutch operable both to inhibit the transfer of torque from the motor to the engine and to facilitate the transfer of torque from the engine to the motor and to the drive shaft without decoupling the engine and the motor rotor; and

a switch having a first position in which the engine is operable, and having a second position in which the engine ignition is grounded but the motor is operable.

16. The drive system of claim 15, wherein the motor includes a stator, and wherein the rotor is spaced axially from the stator to define an axial air gap.

17. The drive system of claim 15, wherein the motor rotor is interconnected with the drive shaft such that the motor rotor rotates in unison with the drive shaft.

18. The drive system of claim 15, wherein the engine includes an engine drive shaft and the clutch connects the engine drive shaft and the motor rotor.

19. The drive system of claim 15, wherein the clutch includes a centrifugal clutch.

20. The drive system of claim 15, wherein the clutch includes a roller clutch.

21. The drive system of claim 15, wherein at least a portion of the clutch is formed as part of the rotor.

22. The drive system of claim 15, wherein the engine operates when the switch is in the first position to rotate the motor rotor and the drive shaft, the rotation of the motor rotor delivering a flow of electrical current to the electrochemical energy source, and wherein when the switch is in the second position the electrochemical energy source delivers a flow of electrical current to the motor such that the motor operates to rotate the drive shaft.

23. The drive system of claim 15, wherein the controller is operable to deliver conditioned power to the electrochemical energy source when the switch is in the first position and to deliver an amount of conditioned power to the motor when the switch is in the second position.

24. The drive system of claim 15 further comprising a tiller arm including a speed control, the speed control operable to control the engine speed when the switch is in the first position and to control the motor speed when the switch is in the second position.

25. The drive system of claim 24, wherein the speed control includes a motor speed adjustment member that is movable between a first position and a second position to provide a signal to the controller to vary the amount of electrical power delivered to the motor.

26. The drive system of claim 25, wherein the motor speed adjustment member includes a potentiometer.

27. A drive system for a marine vessel, the drive system comprising:

a drive shaft rotatable about a drive axis;

a motor including a stator and a rotor that defines a motor axis, the rotor offset from the stator a distance along the motor axis to define an axial air gap, the drive shaft rotating in response to rotation of the rotor at a motor speed;

an engine including an output shaft, the drive shaft and rotor rotating in response to operation of the engine at an engine speed; and

a clutch operable to inhibit the transfer of torque from the motor to the engine and to facilitate the transfer of torque from the engine to the motor and to the drive shaft without manipulating any mechanical connection between the motor, the engine, and the drive shaft.

28. The drive system of claim 27, wherein the motor rotor is interconnected with the drive shaft such that the motor rotor rotates in unison with the drive shaft.

29. The drive system of claim 27, wherein the clutch connects the output shaft and the motor rotor.

30. The drive system of claim 27, wherein the clutch includes a clutched position and a declutched position and wherein the clutch is in the declutched position when the engine speed is below a predetermined speed and is in the clutched position when the engine speed is above the predetermined speed.

31. The drive system of claim 27, wherein the clutch includes a centrifugal clutch.

32. The drive system of claim 27, wherein the clutch includes a roller clutch.

33. The drive system of claim 27, wherein at least a portion of the clutch is formed as part of the rotor.

34. The drive system of claim 27, further comprising a switch having a first position in which the engine is operable, and having a second position in which operation of the engine is inhibited but the motor is operable.

35. The drive system of claim 34, wherein the engine includes an engine ignition that is grounded when the switch is in the second position.

36. The drive system of claim 34, wherein the engine operates when the switch is in the first position to rotate the motor rotor and the drive shaft, the rotation of the motor rotor delivering a flow of electrical current to an electrochemical energy source, and wherein when the switch is in the second position the electrochemical energy source delivers a flow of electrical current to the motor such that the motor operates to rotate the drive shaft.

37. The drive system of claim 34, further comprising a tiller arm including a speed control, the speed control operable to control the engine speed when the switch is in the first position and to control the motor speed when the switch is in the second position.

38. The drive system of claim 37, wherein the speed control includes a motor speed adjustment member movable between a first position and a second position, the motor speed adjustment member providing a signal to the power conditioner to vary the amount of conditioned power delivered to the motor.

39. The drive system of claim 38, wherein the speed adjustment member includes a potentiometer.

40. The drive system of claim 34, further comprising a power conditioner interconnecting the motor and an electrochemical energy source, the power conditioner operable to deliver conditioned power to the electrochemical energy source when the switch is in the first position and to deliver an amount of conditioned power to the motor when the switch is in the second position.