JP2003002289A - Jet propulsion type planning boat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jet propulsion type planning boat enlarging thrust force by using the negative pressure of a water passage generated by a water jet pump, without enlarging the water flow cross section. SOLUTION: This jet propulsion type planning boat provided with an engine arranged in an engine room, and a water jet pump driven by the engine and having a suction port for sucking external water, is constituted to pressurize and accelerate the water sucked by the water jet pump and to jet the water from a jet port at the rear end to advance by the reaction. Bypass water passages 1A, 1B with the rear ends 1b, 1e opened to a negative pressure region near the jet port 21K of the water jet pump P and with the tips 1a, 1d opened into water are provided in line with a suction passage P1 of the water jet pump P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a personal watercraft (Personal Planing Boat) that jets a water stream backward and travels on the water by its reaction.
Watercraft (Personal Watercraft); PWC
It is also called a jet propulsion type planing boat.

[0002]

2. Description of the Related Art So-called jet propulsion type planing boats have been widely used in recent years for leisure, sports or rescue. In this jet propulsion type planing boat, water sucked from a water inlet provided on the bottom surface of the boat is generally pressurized and accelerated by a water jet pump and jetted backward to propel the hull.

In the case of this jet propulsion type planing boat, the steering nozzle arranged behind the jet port of the water jet pump is swung left and right to change the jetting direction of water to the left and right. To steer the boat to the right or left.

By the way, in the case of this jet propulsion type planing boat, the propulsive force (thrust force) of the boat mainly depends on the amount of water jetted backward from the jet nozzle at the rear end of the water jet pump and its jet speed. It is determined. Therefore,
If you want a jet propulsion type planing boat with a larger thrust force, increase the horsepower of the engine and increase the water cross-sectional area of the water jet pump, or in the case of the same water cross-sectional area, It is necessary to increase the rotational speed of the impeller to increase the water passage speed, especially the speed of water jetted backward from the jet nozzle.

When the thrust force is increased by increasing the rotational speed of the impeller, it is impossible to increase the rotational speed above a certain level due to cavitation generated in the impeller portion.

Therefore, generally, when a jet propulsion type planing boat having a larger thrust force is desired, it is often done by enlarging the water passage cross section of the water jet pump.

However, for example, in order to obtain a water jet pump having a thrust force of about 20% larger than that of the current water jet pump, a new water jet pump must be designed and manufactured. , Of course, it is necessary to newly prepare the mold of the water jet pump, of course,
A great deal of effort and cost will be imposed.

The present invention has been made in view of such a situation, and utilizes the negative pressure of the water passage generated by the water jet pump without increasing the water passage cross-sectional area of the water jet pump itself. It is therefore an object of the present invention to provide a jet propulsion type planing boat whose thrust force is easily increased.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above problems by
It can be solved by a jet propulsion type planing boat having the following configuration. That is, a jet propulsion type planing boat according to the present invention is a water jet pump having an engine arranged in an engine room and a water intake port that is driven by the engine and absorbs external water, and sucks the water from the water intake port. In a jet propulsion type planing boat configured to pressurize and accelerate slag water, inject it from the injection port at the rear end of the water jet pump, and propel it by its reaction, in the vicinity of the injection port of the water jet pump. The rear end opens in the negative pressure area (the area where the pressure is negative due to water flow, also called the water negative pressure area),
It is characterized in that a bypass water passage whose tip opens into water is provided in parallel with the water suction passage of the water jet pump.

However, according to the jet propulsion type planing boat constructed as described above, since the rear end of the bypass water passages arranged in parallel is open to the negative pressure region of the water jet pump, Negative pressure is generated in the passage, and water can be sucked into the bypass water passage from the tip of the bypass water passage and discharged from the opening at the rear end. As a result, a new thrust force can be obtained by the water discharged from the rear end of the bypass water passage.

In the jet propulsion type planing boat,
If the tip of the bypass water passage is configured to open on the bottom surface of the boat, the configuration will be simple.

In the jet propulsion type planing boat,
When the tip of the bypass water passage is open to the inside of the water intake port that has entered the wake side from the water intake port of the boat, the water pressure of the water jet pump is a positive portion. Along with the negative pressure at the rear end, a large amount of water can be passed through the bypass water passage, and a larger thrust force can be obtained.

In the jet propulsion type planing boat,
When the tip portion of the bypass water passage is inclined in a direction in which it is deviated to the rear of the boat as it goes to the wake side, water is more positively passed through the bypass water passage when the boat is moving forward. It will be possible to configure.

In the jet propulsion type planing boat,
Forming a negative pressure at the rear end of the bypass water passage by opening the rear end of the bypass water passage in the casing wall surface at the portion where the water passage cross-sectional area behind the injection nozzle of the water jet pump is increased. It is possible to realize a configuration that can.

In the jet propulsion type planing boat,
When the rear end portion of the bypass water passage is inclined in a direction in which it is displaced rearward of the boat as it goes to the wake side, a vector in the same direction as the direction of the water jetted from the jet nozzle becomes Since it is generated in the water discharged from the bypass passage, a large amount of water can be passed through the bypass water passage, and a larger thrust force can be obtained.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a jet propulsion type planing boat according to embodiments of the present invention will be specifically described with reference to the drawings, taking a small planing boat as an example.

FIG. 1 is a partial sectional view in the vicinity of a water jet pump of a boat showing a bypass water passage provided in parallel with a water jet pump of a small planing boat according to an embodiment of the present invention, and FIG. 2 is a bypass passage shown in FIG. FIG. 3 is an overall side view of a small planing boat equipped with a water channel, and FIG. 3 is an overall plan view of the small planing boat shown in FIG.

2 and 3, A is a hull, and this hull A is composed of a hull H and a deck D covering the hull H, and the connecting line connecting the hull H and the deck D over the entire circumference is a gunnel line. In this embodiment, this gunnel line G is located above the waterline L of the small planing boat.

As shown in FIG. 3, an opening 16 of a substantially rectangular shape extending in the longitudinal direction is formed on the upper surface of the hull A at a position slightly rearward of the center of the deck D. As shown in FIG. 3, a seat S for riding is arranged above the opening 16.

The engine E is disposed in a space 20 having a "convex" cross section surrounded by the hull H and the deck D below the seat S. This engine E is a multi-cylinder (four cylinders in this embodiment) fuel injection type four-cycle engine E, and as shown in FIG.
Is mounted so as to extend along the longitudinal direction of the hull A, and the output end of the crankshaft 26 is, via the propeller shaft 27, the pump shaft 21S side of the water jet pump P to which the impeller 21 is attached. , And is rotatably connected integrally. And this impeller 21
Has its outer periphery covered with a pump casing 21C,
Pump that takes in water taken in through the water intake 17 provided on the bottom surface of the small planing boat through the water intake passage, pressurizes and accelerates it with the water jet pump P, and the water passage cross-sectional area decreases toward the rear. It is configured so as to pass through the nozzle (spout portion) 21R and be discharged from the jet port 21K at the rear end to obtain a propulsive force.

Further, in FIG. 2, 21V is a stationary blade for rectifying the water passing through the water jet pump P. Further, in FIGS. 2 and 3, reference numeral 24 denotes a steering wheel which is a steering operation means.
By operating the pump left and right, the pump nozzle 21
Swing the steering nozzle 18 at the rear of the R to the left and right,
When the water jet pump P is in operation, the boat can be steered in a desired direction. Also, handle 2
A throttle lever Lt for controlling the number of revolutions of the engine E is arranged near the grip on the right side of 4.

Further, as shown in FIG. 2, a bowl-shaped reverse deflector 19 is provided above and behind the steering nozzle 18 so as to be swingable downward about a swing shaft 19a arranged horizontally. By oscillating the deflector 19 to the lower position behind the steering nozzle 18, the water discharged rearward from the steering nozzle 18 is turned forward and can be moved backward.

2 and 3, reference numeral 22 denotes a rear deck, which is provided with an opening / closing hatch cover 29, and a storage box of a small capacity (not shown) is provided below the hatch cover 29. ) Has been formed. Further, in FIG. 2 or FIG. 3, 23 is a front hatch cover,
Below the hatch cover 23, a box (not shown) for storing equipment and the like is provided.

By the way, in the small planing boat according to the embodiment of the present invention, the bypass water passages 1A and 1B as shown in FIGS. 1 and 2 are provided in parallel with the water suction passage P1 of the water jet pump P. There is. The bypass waterway 1A
As shown in the enlarged view of FIG. 1, the tip 1a of the water inlet 1 has its tip slightly entering the wake side from the water inlet 17 of the boat.
7 Open inside. And the bypass waterway 1
The rear end 1b of A is directed to the water passage Ps of the water jet pump P on the casing wall surface of the portion 21N where the water passage cross-sectional area behind the injection port 21K of the water jet pump P, which is the water negative pressure region, increases. It is open. Further, as shown in the enlarged view of FIG. 1, the bypass water passage 1B has a tip 1d opening to a bottom surface Bf of the boat, which is separated rearward from the water intake 17 of the boat. The rear end 1e of the bypass water passage 1B is located in the casing wall surface of the portion 21N where the water passage cross-sectional area behind the injection port 21K of the water jet pump P, which is the water passage negative pressure region, increases. It opens toward the water passage Ps. Further, as shown in FIG. 1, the tip portions 1T of the bypass water passages 1A and 1B are inclined in a direction such that they are displaced to the rear of the boat as they go to the wake side, and the boat advances. It is configured such that a positive pressure is generated in the opening portion at the tip when the pressure is present. Further, the rear end portions 1E of the bypass water passages 1A and 1B are inclined in such a direction that they are displaced to the rear of the boat as they go to the wake side, and the direction of the water jetted from the jet nozzle 21R is set. Vectors of the same direction are configured to occur in the water discharged from the bypass passage.

According to the present jet propulsion type planing boat thus constructed, when the water jet pump P operates, the following action is achieved. That is, the water jet pump P operates and the water suction port 17
When the water jet pump P pressurizes / accelerates and injects water from the rear injection port 21K, negative pressure acts on the rear end opening portions of the bypass water passages 1A and 1B. Therefore, each bypass waterway 1
A and 1B suck in external water from the openings 1a and 1d at the tips, and jet water from the openings 1b and 1e at the rear ends formed behind the injection port 21K of the water jet pump P, respectively. In particular, the tip 1a of the bypass water passage 1A
However, since it opens inside the water intake port 17 and the tip 1N is inclined in the direction in which it is displaced to the rear of the boat as it goes to the wake side as described above, it is positively active from the front when the boat is moving forward. Therefore, water is absorbed (absorbed) into the bypass water passage 1A. As described above, in the case of the jet propulsion type planing boat according to the present embodiment, in addition to the water injected through the water absorption path P1 of the water jet pump P itself, external water is also supplied from the bypass water paths 1A and 1B. Since it is sucked and injected backward, a large thrust force that contributes to the forward movement of the boat can be obtained without increasing the water cross-sectional area of the water jet pump P itself.

[0026]

According to the present invention, by utilizing the negative pressure generated behind the injection port of the water jet pump without increasing the water cross-sectional area of the water jet pump itself, the bypass water passage can be connected to the outside. Greater thrust force can be obtained by passing water.

Therefore, even when trying to obtain a large thrust force, it is not necessary to design a new water jet pump, and a mold for each component (poip casing, impeller, etc.) of the new water jet pump is used. No need to prepare separately.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view in the vicinity of a water jet pump of a watercraft showing a bypass water passage provided in parallel with a water jet pump of a small watercraft according to an embodiment of the present invention.

2 is an overall side view of a small planing boat equipped with the bypass water passage shown in FIG. 1. FIG.

3 is an overall plan view of the small planing boat shown in FIG. 2. FIG.

[Explanation of symbols]

P: Water jet pump P1 ... Water absorption path 1A ... Bypass waterway 1B …… Bypass waterway 1a, 1d ... Tip 1b, 1d ... rear end 2E ... Exhaust outlet 21K ... Injection port

Claims (6)

[Claims] 1. A water jet pump having an engine arranged in an engine room and a water intake port that is driven by this engine to absorb external water, and pressurizes and accelerates the water sucked from the water intake port. In a jet propulsion type planing boat configured to eject from a jet end at the rear end of the water jet pump and propel by the reaction thereof, the rear end opens in a negative pressure region near the jet port of the water jet pump. A jet propulsion type planing boat characterized in that a bypass water passage whose tip is open to the water is provided in parallel with the water suction passage of the water jet pump. 2. The jet propulsion type planing boat according to claim 1, wherein a tip of the bypass water passage is opened to a bottom surface of the boat. 3. The jet propulsion-type planing boat according to claim 1, wherein the tip of the bypass water passage opens to the inside of the water intake port that has entered the wake side from the water intake port of the boat. 4. The jet according to claim 2, wherein a tip end portion of the bypass water passage is inclined in a direction such that it is displaced rearward of the boat as it goes to the wake side. Propulsion type planing boat. 5. The rear end of the bypass water passage is opened to a casing wall surface at a portion where the water passage cross-sectional area behind the injection nozzle of the water jet pump is increased. The jet propulsion type planing boat according to any one of items. 6. The jet propulsion according to claim 5, wherein a rear end portion of the bypass water passage is inclined in a direction in which the rear end portion of the bypass water passage is displaced rearward of the boat as it goes to the wake side. Type planing boat.