BOAT PROPELLER

Abstract

A boat propeller includes a gear box, an impeller, a stream-guiding ring, and a stream-shaping nozzle. The gear box has a casing and a transmission shaft partially received in the casing. The impeller has an impeller shaft and vanes. The impeller shaft has a hollow columnar outer shaft housing and a hollow columnar inner shaft housing. The inner and outer shaft housings are connected using a plurality of rib portions. The inner shaft housing is further connected to the transmission shaft of the gear box. The vanes are integrated formed on an outer peripheral surface of the outer shaft. The stream-guiding ring is assembled to the casing of the gear box to house the impeller. The stream-shaping nozzle is connected to a rear end of the stream-guiding ring for providing stream-shaping effects. Thereby, the boat propeller has its water inlet diameter maximized, which helps to improve propulsive efficiency.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to boat propellers, and more particularly to a boat propeller that helps to improve propulsive efficiency.

2. Description of the Related Art

The existing boat propellers structurally have an outer shaft housing, an inner shaft housing, and a plurality of blades. The inner shaft housing is received in the outer shaft and is connected to the inner peripheral surface of the outer shaft through a plurality of rib portions. Each of the blades is integratedly connected to the outer peripheral surface of the outer shaft. When the propeller is driven by an engine to operate at high speed, the blades push water streams backward and the counter force generated thereby can work for propulsion of the boat.

To further enhance propulsion, a known approach is to such design the outer shaft housing that it has a changing cross-sectional area, which becomes smaller as the outer shaft housing extends backward. This helps to accelerate water streams flowing therethrough, and to in turn increase the counter force acting on the boat. However, in practical use, since the outer shaft housing is tapered in shape and the space around the propeller tends to be restricted due to boat design and other factors, the blades are consequently limited in terms of dimensional parameter (such as the rake, the pitch and more). This hinders the blades from effectively compressing water streams, leading to compromised propulsive efficiency.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a boat propeller that has improved propulsive efficiency.

To achieve the foregoing objective, the disclosed propeller comprises a gear box, an impeller, a stream-guiding ring, and a stream-shaping nozzle. The gear box includes a casing and a transmission shaft. The transmission shaft is rotatably installed in the casing, and the transmission shaft has its front end received in the casing so that its rear end juts out the casing. The impeller has an impeller shaft that includes an outer shaft housing and a hollow inner shaft housing, both being hollow columnar. The inner shaft housing is received in the outer shaft housing and is connected to the outer shaft housing through a plurality of rib portions, while being coaxially connected to the transmission shaft of the gear box, so that the impeller is driven by the transmission shaft of the gear box to rotate. In addition, the impeller further has a plurality of vanes that are integratedly formed on the outer peripheral surface of the outer shaft. The stream-guiding ring is assembled to the casing of the gear box and houses the impeller, so that the impeller rotating draws water streams into the stream-guiding ring. The stream-shaping nozzle is connected to the rear end of the stream-guiding ring, for shaping the water stream drawn into the stream-guiding ring.

With the foregoing configuration, the disclosed propeller has its water inlet diameter maximized, thereby improving propulsive efficiency. In addition, with the protection provided by the stream-guiding ring, the impeller is unlikely to harm fishes, swimmers or divers around the bottom of the boat. This allows a boat having a shallow draft safe to be used. Even if the impeller is not fully immersed in water, propulsion can still be provided desirably.

Preferably, the stream-shaping nozzle has a ring portion, a hollow axial portion, and a plurality of stream-shaping portions. The ring portion is connected to the rear end of the stream-guiding ring. The hollow axial portion is defined in the ring portion and coaxially connected to the outer shaft housing of the impeller shaft of the impeller. The stream-shaping portions are connected between the ring portion and the hollow axial portion and arranged equidistantly to circle the hollow axial portion. The stream-shaping nozzle uses the stream-shaping portions to shape the water stream excited by the impeller into linear ejections, thereby facilitating boat propulsion.

Preferably, the casing of the gear box has a tapered shaft. The tapered shaft and the impeller shaft of the impeller do not contact each other. Instead, an exhaust channel is left therebetween. Thereby, when the boat moves backward, the exhaust gas generated by the engine can escape through the exhaust channel and will not interfere with water streams to cause turbulence.

Preferably, the inner shaft housing of the impeller is indirectly connected to the transmission shaft of the gear box through a bushing. The bushing has a shock-absorbing layer and a metal layer wrapping the shock-absorbing layer. In the event that a foreign object comes to the impeller during operation, the shock-absorbing layer serves to absorb impact and prevent the metal layer from burst while protecting the transmission shaft from damage.

The detailed structure, features, assembly and/or use of the boat propeller of the present invention will be explained in detail referred to the following Detailed Description. However, one skilled in the art shall understand that the detailed description and the specific embodiments in which the invention can be practiced are only illustrative and in no way form limitations to the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a boat propeller of the present invention.

FIG. 2 is an exploded view of the boat propeller of the present invention.

FIG. 3 is a point view of an impeller in the boat propeller of the present invention.

FIG. 4 is a side view of the boat propeller of the present invention.

FIG. 5 is a rear view of the boat propeller of the present invention.

FIG. 6 is a partial cross-sectional view of the boat propeller of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

It is to be stated at first that in the disclosure, including the embodiments to be described below and the appended claims, all the directional terms are based on the orientations of them in the drawings. Besides, in the embodiments to be described below and the accompanying drawings, like numerals may refer to identical or similar components or structural features.

Referring to FIG. 1 and FIG. 2, according to the present invention, a boat propeller 10 comprises a gear box 20, an impeller 30, a stream-guiding ring 50, and a stream-shaping nozzle 60.

The gear box 20 is provided with a casing 21. The casing 21 has a tapered shaft 22, an upper wing 23, a lower wing 24, a connecting portion 25 and an anti-swirl baffle 26. The tapered shaft 22 has a changing cross-sectional area that becomes larger as it extends backward. The upper wing 23 and the lower wing 24 are integratedly connected to top and bottom sides of the tapered shaft 22, respectively. The connecting portion 25 is integratedly connected to the top of the upper wing 23 and is configured to engage with an engine housing, which is known in the art and not shown herein. The anti-swirl baffle 26 integratedly is connected between the upper wing 23 and the connecting portion 25. In addition to a gear reduction unit that is known in the art and not shown herein, the gear box 20 further has a transmission shaft 27. The gear reduction unit is installed in the casing 21, and is configured to connect a driving shaft of an engine, both known in the art and not shown herein. The transmission shaft 27 has its front end received in the tapered shaft 22 of the casing 21 and connected to the gear reduction unit. The transmission shaft 27 has its rear end jutting out the casing 21 provided with a toothed portion 28. With the foregoing configuration, the power generated by the engine is transmitted to the gear reduction unit through the driving shaft and then delivered to the transmission shaft 27 after deceleration caused by the gear reduction unit, thereby rotating the transmission shaft 27.

The impeller 30 has an impeller shaft 31 and four vanes 38. As shown in FIG. 3, the impeller shaft 31 has a hollow columnar outer shaft housing 32 and a hollow columnar inner shaft housing 33. The inner shaft housing 33 is coaxially received in the outer shaft housing 32 and is connected to the outer shaft housing 32 through four rib portions 37. The vanes 38 are integratedly connected to the outer peripheral surface of the outer shaft housing 32. Additionally, the outer shaft housing 32 has an engaging flange 34 integratedly extending outward from its rear end (as shown in FIG. 6), and the inner shaft housing 33 has a retaining flange 35 and four positioning recesses 36 formed on the inner peripheral surface in front of the retaining flange 35 (as shown in FIG. 3 and FIG. 6).

Now referring to FIG. 2 and FIG. 6, the impeller 30 is indirectly connected to the transmission shaft 27 of the gear box 20 through a bushing 40. The bushing 40 has a shock-absorbing layer 41 and a metal layer 43 wrapping the shock-absorbing layer 41. The shock-absorbing layer 41 has its outer peripheral surface provided with a plurality of positioning ridges 42, and the metal layer 43 has its inner peripheral surface formed with a toothed channel 44. When assembled to the transmission shaft 27, the bushing 40 is inserted into the inner shaft housing 33 so that its rear end abuts against the retaining flange 35 of the inner shaft housing 33. The bushing 40 on one hand uses the four positioning ridges 42 on the shock-absorbing layer 41 to pair up and engage with the four positioning recesses 36 of the inner shaft housing 33, and on the other hand uses the toothed channel 44 of the metal layer 43 to engage with the toothed portion 28 of the transmission shaft 27. Then two gaskets 46 are arranged at front and rear ends of the impeller shaft 31 for the transmission shaft 27 to pass. At last, a nut 47 is assembled to hold all the components together, thereby making the impeller 30 and the transmission shaft 27 well assembled. As a result, the transmission shaft 27 of the gear box 20 can transmit power generated by the engine to the impeller 30 through the bushing 40, thereby driving the impeller 30 to operate. In the event that a foreign object comes to the impeller 30 during operation, the shock-absorbing layer 41 serves to absorb impact and to prevent the metal layer 43 from burst while protecting the transmission shaft 27 from damage. Moreover, in the assembly of the impeller 30 and the transmission shaft 27, there is no direct contact between the impeller shaft 31 and the tapered shaft 22 of the casing 21. Instead, an exhaust channel 45 is left there between to allow escape of exhaust gas (as shown in FIG. 6).

At the top edge of the outer peripheral surface of the stream-guiding ring 50, two upper supports 51 are symmetrically fixed using fixing members 53 such as screws. The upper supports 51 jointly hold the anti-swirl baffle 26 in position and then the upper supports 51 can be further fixed using fixing members 54 such as screws. At the bottom edge of the outer peripheral surface of the stream-guiding ring 50, a lower support 52 is fixed using fixing members 55 such as screws. The lower support 52 holds the lower wing 24 in position and the lower wing 24 can be further fixed using fixing members 56 such as screws. After so assembled, the stream-guiding ring 50 houses the entire impeller 30.

As shown in FIG. 2 and FIG. 5, the stream-shaping nozzle 60 has a ring portion 61, a hollow axial portion 62, and eight stream-shaping portions 63. The ring portion 61 is fixed to the rear end of the stream-guiding ring 50 using fixing members 64 such as screws. The ring portion 61 has a changing cross-sectional area that becomes smaller as it extends backward. The hollow axial portion 62 is defined in the ring portion 61. The hollow axial portion 62 has its front end provided with an engaging socket 65. The engaging socket 65 of the hollow axial portion 62 coaxially receives the engaging flange 34 of the impeller shaft 31 of the impeller 30 (as shown in FIG. 6). The stream-shaping portions 63 are integratedly connected between the ring portion 61 and the hollow axial portion 62 while being arranged equidistantly to circle the hollow axial portion 62. Thereby, water streams drawn into the stream-guiding ring 50 by the impeller 30 are well shaped into eight linear streams by the eight stream-shaping portions 63 of the stream-shaping nozzle 60. Then the stream-shaping nozzle 60 jets the linear streams backward to provide the boat with propulsion.

With such a design, the boat propeller 10 of the present invention has the following advantageous over the prior-art devices:

1) Given that the stream-guiding ring 50 is attached to the casing 21 of the gear box 20 through the upper and lower supports 51, 52 and that the impeller shaft 31 of the impeller 30 is not tapered, the diameter of the combined vanes 38 is enlarged and so is the water volume to be compressed. As a result, the effective water inlet diameter is maximized to provide improved propulsive efficiency.

2) With the protection provided by the stream-guiding ring 50, the impeller 30 is unlikely to harm fishes, swimmers or divers around to bottom of the boat. This allows a boat having a shallow draft safe to be used. Even if the impeller 30 is not fully immersed in water, propulsion can still be provided desirably. Besides, the stream-guiding ring 50 may be made of aluminum alloy which is of high strength. In this case, the boat propeller 10 is more resident to impact and has a longer service life.

3) When the boat moves backward, the exhaust gas generated by the engine can escape through the exhaust channel 45 and will not interfere with water streams and cause turbulence.

4) The stream-shaping nozzle 60 uses the eight stream-shaping portions 63 to shape the water stream excited by the impeller 30 into linear ejections. This prevents swirls from formed at the back of the impeller 30 and in turn helps to improve propulsive efficiency.

5) The transmission shaft 27 of the gear box 20 and the impeller shaft 31 of the impeller 30 are assembled coaxially, so that the power of the engine can be leveraged, while the bushing 40 works as a buffer against external impacting force.

Claims

1. A boat propeller, comprising:

a gear box, including a casing and a transmission shaft, wherein the transmission shaft is rotatably installed in the casing and has a front end thereof such received in the casing that a rear end thereof juts out the casing;

an impeller, including an impeller shaft and a plurality of vanes, wherein the impeller shaft has a hollow columnar outer shaft, a hollow columnar inner shaft housing, and a plurality of rib portions, in which the inner shaft housing is received in the outer shaft housing and coaxially connected to the transmission shaft of the gear box, and the rib portions are connected between the outer shaft housing and the inner shaft housing, while the vanes are integratedly connected to an outer peripheral surface of the outer shaft housing of the impeller shaft;

a stream-guiding ring, which is assembled to the casing of the gear box and houses the impeller; and

a stream-shaping nozzle, which is connected to a rear end of the stream-guiding ring.

2. The boat propeller of claim 1, wherein the stream-shaping nozzle has a ring portion, a hollow axial portion, and a plurality of stream-shaping portions, in which the ring portion is connected to the rear end of the stream-guiding ring, and the hollow axial portion is defined in the ring portion and coaxially connected to the outer shaft housing of the impeller shaft of the impeller, while the stream-shaping portions are connected between the ring portion and the hollow axial portion and arranged equidistantly to circle the hollow axial portion.

3. The boat propeller of claim 2, wherein the ring portion of the stream-shaping nozzle has a changing cross-sectional area that becomes smaller as the ring portion extends away from the stream-guiding ring.

4. The boat propeller of claim 1, wherein the casing of the gear box has a tapered shaft, and an exhaust channel is formed between the tapered shaft and the impeller shaft of the impeller.

5. The boat propeller of claim 4, wherein the casing of the gear box further has an upper wing, a lower wing, and an anti-swirl baffle, in which the upper wing and the lower wing are integratedly connected to top and bottom sides of the tapered shaft, and the anti-swirl baffle is integratedly connected to the upper wing so it is located above the stream-guiding ring; two upper supports being symmetrically fixed to a top edge of the outer peripheral surface of the stream-guiding ring for connecting the anti-swirl baffle, and a lower support being fixed to a bottom edge of the outer peripheral surface of the stream-guiding ring for connecting the lower wing.

6. The boat propeller of claim 5, wherein the casing of the gear box further has a connecting portion that is integratedly connected to a top of the upper wing so as to be located above the anti-swirl baffle.

7. The boat propeller of claim 1, wherein the inner shaft housing of the impeller is indirectly connected to the transmission shaft of the gear box through a bushing.

8. The boat propeller of claim 7, wherein the inner shaft housing has an inner peripheral surface thereof provided with a positioning recess, and the bushing has an outer peripheral surface thereof provided with a positioning ridge, so that the positioning ridge of the bushing engages with the positioning recess of the inner shaft housing.

9. The boat propeller of claim 8, wherein the bushing has a shock-absorbing layer and a metal layer wrapping the shock-absorbing layer, in which the shock-absorbing layer has an outer peripheral surface thereof provided with the positioning ridge, and the metal layer is connected to the transmission shaft.