JPH0539999Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a small personal watercraft that travels in coastal waters by riding on a deck and holding a steering handle. This invention relates to a jet pump cover that covers a jet pump as a propulsion device to be mounted.

[Conventional technology]

The hull of this type of small personal watercraft is generally formed of a hollow shell made of a plastic molded deck (including FRP) and a hull joined together, and an engine mounted inside the hull drives a propulsion machine at the rear of the bottom. , the steering means is operated by a handle on the deck.

In addition to the propeller, the propulsion device used is a jet pump that obtains propulsive force by injecting water sucked in from the bottom of the ship backwards.In the case of a jet pump, the direction of the injection nozzle is changed from side to side to control steering. Furthermore, by changing the direction of the injection nozzle up and down, the angle of attack during skiing can be adjusted.

This type of small personal watercraft has three types: one where you ride in a standing position on a flat floor deck, one where you ride astride a vertical saddle-shaped seat, and one where you ride in a cockpit formed by recessing most of the deck. Various types have been proposed, such as , and a type in which a bench seat is provided in the middle part of the deck in the longitudinal direction.

By the way, in the case of small watercraft that use a jet pump, the jet pump is generally installed in a recess formed at the rear of the bottom of the boat, and the lower side of the recess is covered with a jet pump cover that forms approximately the same surface as the bottom of the boat. It has been adopted.

Furthermore, it has been proposed that the jet pump cover be provided with an opening inside thereof to drain muddy earth and sand.

Prior art documents disclosing such a small personal watercraft include, for example, Japanese Utility Model Application Publication No. 63-59095.

[Technical problem that the invention attempts to solve]

However, with the conventional jet pump cover that has an opening for removing dirt as described above, when the ship is sailing at an angle of attack (increasing forward slope), the water flow flowing along the bottom of the ship collides with the opening. In some cases, the running resistance did not decrease, which affected the acceleration before entering the runway or the running resistance during the taxiing.

The present invention was developed in view of these technical issues, and is a jet pump cover for a small personal watercraft that can reduce running resistance even when an opening for removing dirt as described above is provided. The purpose is to provide

[Means for solving problems]

The present invention provides a small personal watercraft having a configuration in which a jet pump is mounted in a recess formed at the rear of the bottom of the boat, and the lower side of the recess is covered with a jet pump cover that forms approximately the same surface as the bottom of the boat. An opening that communicates between the inside and outside of the recess is formed, and an inclined surface in the direction in which the water flow separates during navigation and a rear end step are formed on the front side of the opening to reduce the boundary layer flow around the opening. The jet pump cover structure reduces resistance during navigation.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 6 is a longitudinal sectional view of a small personal watercraft equipped with a jet pump cover according to the present invention, FIG. 7 is a perspective view of the small personal watercraft shown in FIG. 6, and FIG.
FIG. 2 is a plan view of the small watercraft shown in FIG.

In these figures, the hull 1 has a structure in which a deck 2 and a hull 3 are joined together at a mating surface 4, and a bench seat 5 is provided at the middle part of the deck 2 in the longitudinal direction. and a floor 6.

A handle post 8 that projects above the cockpit 7 is attached to a portion of the deck 2 on the front side (near the bow) of the cockpit 7.

A handle 15 is pivotally supported at the tip of the handle post, and by operating the handle 15, the jet pump 1 as a propulsion device at the rear of the ship is connected via a control cable 16.
The vehicle is configured to perform steering by changing the direction of the two injection nozzles 14 from side to side.

The throttle lever 15 is provided with a throttle lever (not shown) for controlling the engine 10 that drives the jet pump 12.

The handle 15 has a concave shape as shown in the figure. As the handle 15, in addition to a concave handle as shown in the figure, a round handle, a bar handle, etc. can be freely used.

The bench seat 5 usually has a width that allows two people to sit side by side.

This bench seat 5 is constructed by attaching a cushion made of closed-cell foamed resin to a seat frame (not shown) and covering this with a skin, and fixing the seat frame to the deck 2 by fastening it with bolts or the like. There is.

The driver can sit on the bench seat 5, grip the steering wheel 15, and operate the vehicle in a posture similar to that of a car or an airplane. Armrests 19, 19 (FIG. 8) are formed on both sides of the bench seat 5 of the deck 2 to improve the comfort of the occupants.

Further, the gunwales on both sides of the floor 6 of the cockpit 7 are lowered to a position close to the floor 6, and the lowered gunwales 20, 20 (FIG. 8) provide entrances and exits for boarding and alighting. It is formed.

Inside the front part of the hull 1 is a fuel tank 9 (sixth tank).
) is installed.

Further, the tip end surface 24 of the handle post 8 is
It is a dash board with a tachometer that displays engine speed, a fuel gauge that displays remaining fuel, and a main switch.

The jet pump 12 is attached to the dart board 24 in order to adjust the angle of attack when the hull 1 is planing.
An operating lever such as a tilt lever for remotely controlling the direction of the injection nozzle 14 up or down, or a reverse lever for remotely controlling a reverse bucket for driving backwards can also be attached.

The deck 2 and the hull 3 are made of, for example, molded plastic (including FRP).

The front part of the deck 2 has a streamlined shape that bulges out from the bow, and an engine 10 is mounted inside the hull below the bench seat 5 slightly toward the rear of the deck 2. 10 is configured to drive the jet pump 12 at the rear of the boat via a propeller shaft 11.

The inside of the hollow hull 1 is partitioned into front and rear parts by a bulkhead 21 that crosses the hull 1, and the rear half is an engine room 22 in which the engine 10, the jet pump 12, etc. are stored.

FIG. 5 is a partial vertical sectional view showing an enlarged portion of the jet pump 12 of the personal watercraft shown in FIG.

In FIGS. 5 and 6, the jet pump 12 used is one that obtains propulsive force by injecting water sucked in from the bottom opening 13 rearward.

The part of the deck 2 that forms the upper part of the engine room 22 constitutes an engine hood 25 for inspection and maintenance that can be opened and closed, and in the illustrated example, it can be opened along a dividing line 26. A hinge 27 is provided at the rear of the split line 26, and a clamp 28 is provided at the front of the dividing line 26.

The engine hood 25 has an opening/closing lid 29. The jet pump 12 is installed in a recess 41 formed at the rear of the bottom of the ship, and the bottom of the recess 41 has a surface substantially the same as the bottom of the ship (lower surface of the hull 3) 17. A jet pump cover 42 is attached.

In this way, a smooth boat bottom is formed in which the jet pump 12 does not protrude or be exposed from the boat bottom 17.

A water suction duct 43 is provided at the front of the jet pump 12, and the tip of the water suction duct 43 is attached so as to coincide with the bottom 17, forming the bottom opening 13.

An inspection hole 44 is formed in the upper part of the water suction duct 43 for maintenance and inspection of the inside of the duct 43 and the jet pump 12 from the deck 2 side, and this inspection hole 44 normally has a removable blind cover 45. is sealed.

The injection nozzle 14 is attached to the jet pump 12 so that the angle can be adjusted (steering) left and right, and the injection nozzle 14 has a structure that can further adjust the angle up and down (tilt operation) as necessary. ing.

Steering to change the direction of the injection nozzle 14 left and right is performed by the handle 15 and control cable 16 shown in FIG.

The tilt operation for adjusting the angle of attack during skiing is remotely controlled by a tilt lever (not shown) or the like.

At the rear of the jet pump 12 (in the illustrated example, the injection nozzle 14) is provided with a bowl-shaped jet pump that can be rotated between a normal position shown by a solid line and a reverse position shown by a two-dot chain line, as shown in FIG. reverse bucket 1
8 is attached.

During normal running, the reverse bucket 18 is in the non-operating position as shown by the solid line, and jets the jet water stream from the injection nozzle 14 backwards as it is, but it is located directly behind the injection nozzle 14 as shown by the two-dot chain line. When rotated to the astern position, the direction of the jet water flow from the injection nozzle 14 is changed forward and downward, causing the small personal watercraft to travel astern.

If the reverse bucket 18 is stopped midway and set in a position where the jet water is ejected directly downward, a so-called neutral setting can be achieved.

It is generally preferable to start the engine 10 while the ship is stopped, and for this purpose a mechanism that can set the reverse lever to a neutral position may be employed.

FIG. 1 is a perspective view of the jet pump cover 42 shown in FIGS. 5 and 6, and FIG. 2 is a longitudinal sectional view of the central portion of the jet pump cover 42 shown in FIG.

In FIGS. 1 and 2, an opening 47 is formed in the center of the jet pump cover 42 at a slightly rearward position, which communicates between the inside and outside of the recess 41 (FIG. 5). Pump cover 42
The outer surface has an inclined surface 51 in the direction in which the water flow separates during running and a rear end stepped portion 52 on the front side of the opening 47 to reduce the boundary layer flow around the opening 47 ( water flow diverting means (including cases where it is eliminated) is constructed.

The inclined surface 51 may be any surface that makes the boundary layer flowing along the ship bottom 17 rise even slightly from the ship bottom surface 17 in the region of the opening 47, as shown by arrow A in FIG. 2, for example, It is formed of a flat or curved surface corresponding to a slope of about 1 to 3 degrees.

Further, the rear end stepped portion 52 is a stepped portion between the rear end of the inclined surface 51 and the bottom surface 17, and is formed at a position immediately in front of the opening 47 or at a position coinciding with the front edge as shown in the figure.

According to the embodiment described above, the opening 47 is formed in the jet pump cover 42, and the inclined surface 51 is formed on the bottom surface of the ship in front of the opening 47 in the direction in which the water flow A is separated during running. Since the stepped portion 52 is formed just before the opening 47 and at the rear end of the inclined surface 51, the opening 47 can be provided to improve soil removal performance, and at the same time, the opening 4
It has been possible to provide a jet pump cover for a small personal watercraft that can reduce running resistance during planing by preventing water flow from colliding with the periphery of the personal watercraft.

FIG. 3 is a longitudinal sectional view showing another embodiment of the jet pump cover for a personal watercraft according to the present invention.

A in FIG. 3 has openings 47 formed at two locations in the front and back, and water flow deflecting means consisting of an inclined surface 51 and a rear end step 52 similar to those in FIGS. 1 and 2 is provided on the front side of each opening 47. The configuration to be provided is shown.

B in FIG. 3 is the same as A in which the opening 47 is formed at a position recessed upward from the bottom 17, and the inclined surface 51 and the rear end stepped portion 52 are formed so as not to protrude from the bottom 17. .

C in FIG. 3 shows the water flow deflecting means consisting of the inclined surface 51 and the rear end stepped portion 52 similar to those described above.
The jet pump cover 42 is formed in two stages in the front-rear direction, and an opening 47 is formed in the end face of each rear end stepped portion 52.

In each of the embodiments shown in A, B, and C of FIG. 3, an opening 47 is provided to secure a dirt removal hole, as in the case of FIG. 1 and FIG. A jet pump cover for a small personal watercraft that can prevent water collisions and reduce running resistance during planing has been obtained.

In the above embodiment, the opening 47 is circular, but the opening 47 may have a square shape, a square shape, a square shape, or a square shape.
The shape can be freely selected, such as triangular or oval.

FIG. 4 is a perspective view of a jet pump cover 42 in which the opening 47 is rectangular.

In this case, the rear end stepped portion 52 of the inclined surface 51 is formed in an area slightly wider than the width of the opening 47.

In the embodiment shown in FIG. 4, the same functions and effects as in the above-mentioned embodiments were obtained.

Note that the aforementioned openings 47 may be formed in a plurality of positions side by side, and the present invention can be similarly applied to such a case.

[Effect of idea]

As is clear from the above description, according to the present invention, a jet pump is mounted in a recess formed at the rear of the ship's bottom, and the lower side of the recess is covered with a jet pump cover that forms approximately the same surface as the ship's bottom. In the small personal watercraft having the above, an opening is formed in the cover to communicate between the inside and outside of the recessed part, and an inclined surface and a rear end step part are formed in the front side of the opening in a direction in which water flow is separated during running, and the Since the boundary layer flow around the opening is reduced, there is provided a jet pump cover for a small personal watercraft that can reduce running resistance during planing even when an opening for removing dirt is provided.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an embodiment of the jet pump cover for a small personal watercraft according to the present invention, Fig. 2 is a central vertical cross-sectional view of Fig. 1, and A, B, and C in Fig. 3 are each according to the present invention. Fig. 4 is a perspective view showing still another embodiment of the jet pump cover according to the present invention, and Fig. 5 is a longitudinal sectional view showing various embodiments of the jet pump cover according to the present invention. FIG. 6 is a schematic vertical sectional view of a small personal watercraft equipped with a jet pump cover according to the present invention;
7 is a perspective view of FIG. 6, and FIG. 8 is a plan view of FIG. 6. 1... Hull, 10... Engine, 12... Jet pump (propulsion machine), 14... Injection nozzle, 1
7...Bottom, 41...Recess, 42...Jet pump cover, 47...Opening, 51...Slanted surface, 5
2... Rear end step part.

Claims (1)

[Scope of utility model registration request] In a small personal watercraft, a jet pump is mounted in a recess formed at the rear of the bottom of the boat, and the lower side of the recess is covered with a jet pump cover that forms approximately the same surface as the bottom of the boat. A communicating opening is formed, and an inclined surface and a rear end step part are formed in the direction in which the water flow separates during running on the front side of the opening, thereby reducing the boundary layer flow around the opening. A jet pump cover for a small personal watercraft.