WATER JET PROPULSION BOAT AND BOAT

Abstract

A water jet propulsion boat includes a boat body including a keel, and a cavity in a front portion of the keel extending in a left-right direction of the boat body.

Claims

1. A water jet propulsion boat comprising: a boat body including a keel; and a cavity in a front portion of the keel extending in a left-right direction of the boat body.

2. The water jet propulsion boat according to claim 1, wherein at least a portion of the cavity is below a waterline of the water jet propulsion boat when the water jet propulsion boat is travelling.

3. The water jet propulsion boat according to claim 2, wherein a portion of a front side of the cavity is above the waterline when the water jet propulsion boat is travelling.

4. The water jet propulsion boat according to claim 1, wherein the cavity is adjacent to a lower surface of the boat body.

5. The water jet propulsion boat according to claim 1, wherein the boat body includes: a boat main body; and a plate including a front end portion and a rear end portion each connected to a lower portion of the boat main body, and a middle portion between the front end portion and the rear end portion spaced apart from the boat main body in an upper-lower direction of the boat body; wherein the cavity defines a space between the boat main body and the plate.

6. The water jet propulsion boat according to claim 5, wherein, when viewed in the left-right direction, an upper contour line of the plate includes a curved shape or a shape including a portion bent at an angle of more than about 90 degrees and less than about 180 degrees.

7. The water jet propulsion boat according to claim 5, wherein, when viewed in the left-right direction, a lower contour line of the plate includes a curved shape.

8. The water jet propulsion boat according to claim 5, wherein the plate has a cross-section intersecting the front-rear direction such that a central portion of the plate located adjacent a centerline of the boat body in the left-right direction projects downward.

9. The water jet propulsion boat according to claim 8, wherein the plate has a cross-section intersecting the front-rear direction that is triangular or substantially triangular in shape, and includes a corner located adjacent the centerline of the boat body in the left-right direction and that projects downward.

10. The water jet propulsion boat according to claim 5, wherein, when viewed in the left-right direction, an angle between the rear end portion of the plate and the boat main body is less than an angle between the front end portion of the plate and the boat main body.

11. The water jet propulsion boat according to claim 5, wherein the plate is removably connected to the boat main body.

12. The water jet propulsion boat according to claim 1, wherein, when viewed in an upper-lower direction of the boat body, a rearward contour line of the cavity includes a center portion adjacent to a left-right centerline of the boat body and that projects forward.

13. The water jet propulsion boat according to claim 12, wherein, when viewed in the upper-lower direction, the rearward contour line of the cavity includes a corner adjacent to the left-right centerline of the boat body and that projects forward.

14. The water jet propulsion boat according to claim 1, wherein the cavity extends in a front-rear direction of the boat body.

15. The water jet propulsion boat according to claim 1, wherein the cavity includes a plurality of cavities in the front portion of the keel that are aligned in a front-rear direction of the boat body.

16. A boat comprising: a boat body including a keel; and a cavity in a front portion of the keel extending in a left-right direction of the boat body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a side view schematically illustrating a water jet propulsion boat according to an example embodiment of the present invention.

[0012] FIG. 2 is an explanatory view illustrating a cavity and its surroundings according to an example embodiment of the present invention.

[0013] FIG. 3 shows a cross-section of the boat body taken along line III-III of FIG. 2.

[0014] FIG. 4 shows a cross-section of the boat body taken along line IV-IV of FIG. 2.

[0015] FIG. 5 is an explanatory view illustrating a cavity and its surroundings according to another example embodiment of the present invention.

[0016] FIG. 6 shows a cross-section of the boat body taken along line IV-IV of FIG. 2.

[0017] FIG. 7 is a side view schematically illustrating a water jet propulsion boat according to another example embodiment of the present invention.

[0018] FIG. 8 is a side view schematically illustrating a water jet propulsion boat according to a modified example embodiment.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0019] FIG. 1 is a side view schematically illustrating a water jet propulsion boat 10 according to an example embodiment of the present invention. In each of the following figures, arrows representing each direction with respect to the position of the water jet propulsion boat 10 are indicated as appropriate. More specifically, each figure shows arrows representing the front direction (FRONT), rear direction (REAR), left direction (LEFT), right direction (RIGHT), upper direction (UPPER), and lower direction (LOWER), respectively, as appropriate. The front-rear direction, left-right direction, and upper-lower (vertical) direction are orthogonal to each other. FIG. 1 also shows the waterline W of the water jet propulsion boat 10 when it is travelling.

[0020] The water jet propulsion boat 10 according to the present example embodiment is, e.g., a personal watercraft (PWC). The water jet propulsion boat 10 includes a boat body 20, a drive device 30, a jet propulsion mechanism 40, a jet stream adjustment mechanism 50, a displacement mechanism 60, a steering device 70, and a control device (ECU) 80.

[0021] The boat body 20 is the main structure of the water jet propulsion boat 10. The boat body 20 includes a keel 26 extending from the bow to the stern in the center of the boat body bottom in the left-right direction. The keel extends from the bow to the stern at the centerline location of the boat body at the bottom of the boat body. The keel is coupled to bow and stern members. The keel corresponds to the backbone of the boat body. The keel herein may include a portion of the stem in the boat body. As will be described in detail below, a cavity 29 is provided at the front portion of the keel 26 in the boat body 20.

[0022] The boat body 20 includes a boat main body 27 and a plate 28. The boat main body 27 includes a hull 21, a deck 22, and a seat 23. The hull 21 defines the bottom of the boat body 20. The deck 22 defines the top portion of the boat body 20. The seat 23 is disposed in the center or substantial center of the boat body 20 in the front-rear direction. The seat 23 can be used to seat a user (crew member), not shown. The plate 28 connected to the lower portion of the boat main body 27. The plate 28 is positioned at the front portion of the keel 26.

[0023] The drive device 30 is located at a lower portion of the boat body 20. The drive device 30 includes an engine 31, a crank shaft 32, and a coupling 33. The engine 31 is a spark-ignition multi-cylinder internal combustion engine. The crank shaft 32 is a rotating shaft that outputs the drive torque generated by the engine 31. The crank shaft 32 extends rearward from the engine 31. The coupling 33 connects the crank shaft 32 to the impeller shaft 45 described below. The coupling 33 transmits the drive torque of the crank shaft 32 to the impeller shaft 45.

[0024] The jet propulsion mechanism 40 is located in the rear portion of the hull 21 of the boat body 20. The jet propulsion mechanism 40 includes an impeller housing 43, an impeller 44, an impeller shaft 45, stator blade 46, and a nozzle 47. The jet propulsion mechanism 40 includes a flow path 41 therein.

[0025] The flow path 41 is provided in the rear portion of the hull 21 of the boat body 20 and in the center portion in the left-right direction. One end of the flow path 41 opens downward from the hull 21 as a water inlet 42 to intake water. The flow path 41 extends rearward from the water inlet 42. The other end 49 of the flow path 41 opens rearward from the hull 21.

[0026] The impeller housing 43 is a substantially cylindrical body extending in the front-rear direction. The impeller housing 43 protrudes from the other end 49 of the flow path 41 rearward of the hull 21. The impeller 44 is housed within the impeller housing 43. The impeller 44 is connected to the rear end of the impeller shaft 45. The impeller 44 rotates integrally with the impeller shaft 45 about the central axis of the impeller shaft 45. The stator blade 46 is located behind the impeller 44 in the impeller housing 43. The nozzle 47 has a cylindrical shape. The nozzle 47 is fixed to the rear end of the impeller housing 43. The rear end of the nozzle 47 is open as a jet outlet 48 to eject water.

[0027] When the drive torque generated by the engine 31 is transmitted to the impeller shaft 45 and the impeller 44 rotates accordingly, water from outside the boat body 20 is drawn into the flow path 41 through the water inlet 42. The water drawn into the flow path 41 is supplied by the impeller 44 to the stator blade 46. The water supplied by the impeller 44 is rectified by passing through the stator blade 46. The rectified water passes through the nozzle 47 and is ejected from the jet outlet 48 to the rearward of the boat body 20. In this way, the jet propulsion mechanism 40 can generate a jet stream directed rearward of the boat body 20.

[0028] The jet stream adjustment mechanism 50 includes a deflector 51 and a reverse gate 52. The displacement mechanism 60 includes a deflector moving mechanism 61 and a reverse gate moving mechanism 65.

[0029] The deflector 51 is substantially cylindrical (conical) in shape, with the inner diameter decreasing toward the rear. The deflector 51 is positioned behind the nozzle 47. The deflector 51 covers the jet outlet 48 of the nozzle 47. The jet stream ejected from the jet outlet 48 passes through the deflector 51 and is ejected from the outlet 53. The deflector 51 is rotatable about a vertical and horizontal axis behind the jet outlet 48. Depending on its rotational position, the deflector 51 can change the left-right direction and the upper-lower direction of the jet stream that is ejected from the jet outlet 48 to the rearward of the boat body 20. The deflector moving mechanism 61 displaces the deflector 51 in response to operations by the steering device 70.

[0030] The reverse gate 52 is located behind the deflector 51. The reverse gate 52 is displaceable to a forward movement position, a neutral position, and a backward movement position. The forward movement position does not cover the outlet 53 of the deflector 51. The neutral position partially covers the outlet 53 of the deflector 51. The backward movement position covers the entire outlet 53 of the deflector 51.

[0031] The steering device 70 includes, e.g., a steering wheel. A user of the water jet propulsion boat 10 can grasp the grips provided at both ends of the steering handle and rotate the steering handle. When the user rotates the steering handle, the deflector 51 can be rotated left or right via the displacement mechanism 60. The steering device 70 includes a plurality of manual operators (not shown). The user can start and stop the engine 31, rotate the deflector 51 in the upper-lower direction, or rotate the reverse gate 52 by operating the manual operators.

[0032] The ECU 80 includes, e.g., a CPU, a multi-core CPU, or a programmable device (e.g., field programmable gate array (FPGA) and programmable logic device (PLD)). The ECU 80 operates the deflector moving mechanism 61 and the reverse gate moving mechanism 65 in response to operations by, e.g., the steering device 70.

[0033] FIG. 2 is an explanatory view of the cavity 29 and its surroundings in the present example embodiment. FIG. 2 shows the cavity 29 and its surroundings when viewed in the left-right direction. As shown in FIG. 2, the cavity 29 is provided in the boat body 20 and penetrates or extends through the boat body 20 in the left-right direction. The cavity 29 is located at the front portion of the keel 26 in the boat body 20. In other words, the cavity 29 is located near or adjacent to the lower surface of the boat body 20. The cavity 29 in this example embodiment has a shape that extends in the front-rear direction. According to this example embodiment of the water jet propulsion boat 10, when the water jet propulsion boat 10 turns, water around the bottom of the boat body 20 passes through the cavity 29. Therefore, the water jet propulsion boat 10 can easily turn smoothly by reducing the resistance of the water applied to the bottom of the boat body 20 when turning.

[0034] The cavity 29 is defined by a space located between the boat main body 27 and the plate 28. As shown in FIG. 2, the plate 28 includes a front end portion 281, a rear end portion 282, and a middle portion 283. The front end portion 281 is the front side of the plate 28. The rear end portion 282 is the rear side of the plate 28. The middle portion 283 is located between the front end portion 281 and the rear end portion 282. The front end portion 281 and the rear end portion 282 of the plate 28 are connected to the lower portion of the boat main body 27. When viewed in the left-right direction, an upper contour line of the plate 28 has or includes a curved shape. In addition, when viewed in the left-right direction, a lower contour line of the plate 28 has or includes a curved shape. In other words, the plate 28 has or includes a curved shape so that the middle portion 283 protrudes downwardly when viewed in the left-right direction. Because the plate 28 has such a structure, the middle portion 283 of the plate 28 is separate and spaced apart from the boat main body 27 in the upper-lower direction. This provides the space between the boat main body 27 and the plate 28.

[0035] Since the water jet propulsion boat 10 creates the cavity 29 by attaching the plate 28 to the boat main body 27, it is not necessary, e.g., to provide the cavity by piercing a portion of the boat main body from the left side to the right side. As a result, the water jet propulsion boat 10 can be manufactured relatively easily, because the process of piercing a portion of the boat main body from right to left, e.g., is not required at the time of manufacturing the water jet propulsion boat 10. Furthermore, the cavity 29 can be provided without reducing the strength of the boat main body 27 because it is not necessary to pierce a portion of the boat main body 27.

[0036] The plate 28 is attached to the boat main body 27 by, e.g., bolts. In other words, the plate 28 is removably connected to the boat main body 27. This makes it possible, e.g., to replace the plate 28 with another plate that has a different shape than the plate 28, and to change the characteristics of the water jet propulsion boat 10 accordingly.

[0037] As shown in FIG. 1, at least a portion of the cavity 29 is located below the waterline W when the water jet propulsion boat 10 is travelling. A portion of the front side of the cavity 29 may be located above the waterline W when the water jet propulsion boat 10 is travelling. Because a portion of the front side of the cavity 29 is located above the waterline W, the water jet propulsion boat 10 can reduce water resistance on the bottom of the boat body 20 when traveling straight ahead and improve propulsive efficiency.

[0038] As shown in FIG. 2, when viewed in the left-right direction, the angle 1 between the rear end portion 282 of the plate 28 and the boat main body 27 is less than the angle 2 between the front end portion 281 of the plate 28 and the boat main body 27. In other words, the distance between the boat main body 27 and the plate 28 is shorter on the rear side of the cavity 29 than on the front side of cavity 29. This structure reduces or prevents the water jet propulsion boat 10 from turning more than intended when turning.

[0039] FIG. 3 shows a cross-section of the boat body 20 of the present example embodiment taken along line III-III of FIG. 2. FIG. 3 shows a cross-section of the boat body 20 that intersects the front-rear direction, e.g., orthogonal to the front-rear direction. FIG. 3 shows the centerline CL, which is the centerline of the boat body 20 in the left-right direction.

[0040] The cross-section intersecting the front-rear direction at the plate 28 is bounded by a straight section L1, a curved section C1, and a curved section C2. The straight section L1 extends in the left-right direction and faces the boat main body 27 in the upper-lower direction. The left end of the straight section L1 is located to the left of the centerline CL, and the right end of the straight section L1 is located to the right of the centerline CL. The left end of the curved section C1 intersects the left end of the straight section L1. The right end of the curved section C1 is located lower than the left end of the curved section C1 and near the centerline CL. The curved section C1 is curved so that the middle portion from the left end to the right end protrudes to the lower left. The right end of the curved section C2 intersects the right end of the straight section L1. The left end of the curved section C2 is located lower than the right end of the curved section C2 and near the centerline CL. The curved section C2 is curved so that the middle portion from the left end to the right end protrudes to the lower right. The right end of the curved section C1 and the left end of the curved section C2 intersect near the centerline CL, and the intersection of the right end of the curved section C1 and the left end of the curved section C2 forms a corner E1. That is, the plate 28 has a cross-section intersecting the front-rear direction with a central portion located near the centerline CL and projecting downward. More precisely, the cross-section intersecting the front-rear direction of the plate 28 is triangular or substantially triangular in shape with the corner E1 located near the centerline CL and projecting downward. Because of this structure of the plate 28, the water jet propulsion boat 10 can improve the seaworthiness when traveling straight ahead.

[0041] FIG. 4 shows a cross-section of the boat body 20 according to an example embodiment taken along line IV-IV of FIG. 2. FIG. 4 shows a cross-section of the boat body 20 that intersects the upper-lower direction of the boat body 20. The cross-section shown in FIG. 4 shows a portion of the boat main body 27 that defines a rearward contour line 290 of the cavity 29. FIG. 4 shows the centerline CL of the boat body 20 in the left-right direction.

[0042] When viewed in the upper-lower direction, the rearward contour line 290 of the cavity 29 includes a central portion located near the left-right centerline CL of the boat body 20 and that projects forward. More particularly, when viewed in the upper-lower direction, the rearward contour line 290 of the cavity 29 includes a corner E2 located near the left-right centerline CL of the boat body 20 and that projects forward. In other words, the portion of the boat body 20 defining the rearward contour line 290 of the cavity 29 continuously narrows in the left-right direction toward the front. Because the boat body 20 has such a structure, the water jet propulsion boat 10 can reduce the resistance of water applied to the bottom of the boat body 20 when traveling forward, thus improving propulsion efficiency.

[0043] FIG. 5 is an explanatory view illustrating a cavity 29a and its surroundings according to another example embodiment. In the following, portions of the boat body 20a of the another example embodiment that are common to the boat body 20 of the example embodiments described above will be marked with the same symbols, and their description will be omitted as appropriate.

[0044] The boat body 20a of the present example embodiment differs from the boat body 20 in the shape of the plate. Specifically, when viewed in the left-right direction, the upper contour line of the plate 28a has a shape including a portion that bends at an angle of more than about 90 degrees and less than about 180 degrees. When viewed in the left-right direction, the upper contour line of the plate 28a includes a corner E3 that is bent by an angle 3 and a corner E4 that is bent by an angle 4. Due to this structure of the plate 28a, the middle portion 283 of the plate 28a is separated and spaced apart from the boat main body 27 in the upper-lower direction, as in the case of the boat body 20. This defines a space between the boat main body 27 and the plate 28a. The angles 3 and 04 are both between about 90 and about 180 degrees. Since both the angle 3 and the angle 4 are between about 90 and about 180 degrees, the plate 28a can be more gently curved than, e.g., in the case where the angle 3 or the angle 4 is less than 90 degrees. This enables the water jet propulsion boat to reduce the resistance of water on the bottom of the boat body 20a when traveling straight ahead, thus improving propulsion efficiency.

[0045] The water jet propulsion boat provided with the boat body 20a of the present example embodiment also has the same effects as the water jet propulsion boat 10 of the above example embodiments. That is, according to the water jet propulsion boat of the present example embodiment, when the water jet propulsion boat turns, water around the bottom of the boat body 20a passes through the cavity 29a. Therefore, the water jet propulsion boat can easily turn smoothly by reducing the resistance of the water applied to the bottom of the boat body 20a when turning.

[0046] FIG. 6 shows a cross-section of the boat body 20b of another example embodiment taken along line III-III of FIG. 2. In the following, portions of the boat body 20b of the another example embodiment that are common to the boat body 20 of the example embodiments described above will be marked with the same symbols, and their description will be omitted as appropriate.

[0047] The boat body 20b of the present example embodiment differs from the boat body 20 in the shape of the cross-section intersecting the front-rear direction of the plate. Specifically, in the boat body 20b, the cross-section of the plate 28b intersecting the front-rear direction is surrounded by a curved section C1, a curved section C2, and a curved section C3. The curved section C3 extends in the left-right direction and faces the boat main body 27 in the upper-lower direction. The left end of the curved section C3 is located to the left of the centerline CL, and the right end of the curved section C3 is located to the right of the centerline CL. The curved section C3 is curved so that the middle portion from the left end to the right end protrudes upward. The left end of the curved section C1 intersects the left end of the curved section C3. The right end of the curve C2 intersects the right end of the curved section C3. In other words, in the boat body 20b, the plate 28b has a cross-section intersecting the front-rear direction with a central portion located near the centerline CL and that projects upward.

[0048] The water jet propulsion boat provided with the boat body 20b of the present example embodiment also has the same effects as the water jet propulsion boat 10 of the example embodiments described above. That is, according to the water jet propulsion boat of the present example embodiment, when the water jet propulsion boat turns, water around the bottom of the boat body 20b passes through the cavity 29b. Therefore, the water jet propulsion boat can easily turn smoothly by reducing the resistance of the water applied to the bottom of the boat body 20b when turning.

[0049] FIG. 7 is a side view schematically illustrating a water jet propulsion boat 10c according to another example embodiment. In the following, portions of the water jet propulsion boat 10c of this present example embodiment that are common to the water jet propulsion boat 10 of the example embodiments described above will be marked with the same symbols, and their description will be omitted as appropriate.

[0050] The water jet propulsion boat 10c of the present example embodiment differs from the water jet propulsion boat 10 in its boat body structure. Specifically, the water jet propulsion boat 10c includes a boat body 20c. A plurality of cavities 29c are provided in the front portion of the keel 26 in the boat body 20c, which are aligned in the front-rear direction. The boat body 20c includes a boat main body 27 and a plate 28c. The plate 28c is connected to the lower portion of the boat main body 27 so that no gap is provided between the plate 28c and the boat main body 27. The plate 28c includes a plurality of cavities 29c that penetrate or extend in the left-right direction. The plurality of cavities 29c are, for example, circular when viewed in the left-right direction.

[0051] The water jet propulsion boat 10c of the present example embodiment also has the same effects as the water jet propulsion boat 10 of the example embodiments described above. That is, according to the water jet propulsion boat 10c of the present example embodiment, when the water jet propulsion boat 10c turns, water around the bottom of the boat body 20c passes through the cavities 29c. Therefore, the water jet propulsion boat 10c can easily turn smoothly by reducing the resistance of water applied to the bottom of the boat body 20c when turning.

[0052] The technologies disclosed herein are not limited to the above-described example embodiments and may be modified in various ways without departing from the gist of the present invention, including the following modifications.

[0053] FIG. 8 is a side view schematically illustrating a water jet propulsion boat 10d according to a modified example embodiment. In the following, portions of the water jet propulsion boat 10d of the modified example embodiment that are common to the water jet propulsion boat 10 of the example embodiments described above will be marked with the same symbols, and their description will be omitted as appropriate.

[0054] The water jet propulsion boat 10d according to the modified example embodiment differs from the water jet propulsion boat 10 in its boat body structure. Specifically, the water jet propulsion boat 10d includes a boat body 20d. The boat body 20d includes a boat main body 27 and an attachment 128. The attachment 128 is connected to the lower portion of the boat main body 27 so that no gap is provided between the attachment 128 and the boat main body 27. The attachment 128 is located at the front portion of the keel 26. In other words, the water jet propulsion boat 10d according to the modified example embodiment includes the attachment 128 instead of the plate 28 in the water jet propulsion boat 10 of the example embodiments described above. The attachment 128 includes a plurality of notches from the front end to the rear end when viewed in the left-right direction. Therefore, the lower contour line of the attachment 128 has a shape in which convex and concave portions are repeated from the front to the rear when viewed in the left-right direction. That is, gaps 129 are provided in the portion of the attachment 128 where the concave portion is located.

[0055] The water jet propulsion boat 10d according to the modified example embodiment also has the same effects as the water jet propulsion boat 10 of the example embodiments described above. That is, according to the water jet propulsion boat 10d, when the water jet propulsion boat 10d turns, water around the bottom of the boat body 20d passes through the gaps 129. Therefore, the water jet propulsion boat 10d can easily turn smoothly by reducing the resistance of water applied to the bottom of the boat body 20d when turning.

[0056] In the above example embodiments, the engine 31 is illustrated as the drive source of the drive device 30, but an electric motor or the like may be provided together with or instead of the engine 31.

[0057] In the above example embodiments, a portion of the front side in the cavity 29 is located above the waterline W when the water jet propulsion boat 10 is travelling, but the configuration is not necessarily limited thereto, e.g., the entire cavity may be located below the waterline when the water jet propulsion boat is travelling.

[0058] In the above example embodiments, the boat body 20 of the water jet propulsion boat 10 includes a plate 28, but the configuration is not necessarily limited thereto, and the boat body of the water jet propulsion boat may include a cavity having a different structure.

[0059] In the above example embodiments, the upper contour line in the plate 28a includes a corner E3 and a corner E4 when viewed in the left-right direction, but there may be one corner or three or more corners.

[0060] The shape of the plate in the water jet propulsion boat is not limited to the above example embodiments but can be modified in various ways.

[0061] In the above example embodiments, a PWC is shown as an example of the application of the technologies disclosed herein, but the technologies disclosed herein can be applied to vessels in general, such as sport boats, for example.

[0062] While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.