JP4463443B2 - Jet-propelled planing boat - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a jet-propelled planing boat such as a small planing boat (personal watercraft (also called PWC)) that jets a water flow backward and sails on the water by its reaction.
[0002]
[Background Art and Problems to be Solved by the Invention]
In recent years, so-called jet-propelled planing boats have been widely used for leisure, sports or rescue. In this jet propulsion type personal watercraft, generally, water sucked from a water inlet provided on the bottom of the boat is pressurized and accelerated by a water jet pump and propelled backwards to propel the hull.
[0003]
And in the case of this jet propulsion type personal watercraft, by changing the direction of water injection to the left and right by swinging the steering nozzle arranged behind the water jet pump injection port to the left and right, Steer the boat to the right or left.
[0004]
By the way, in the case of this jet propulsion type personal watercraft, the propulsive force (thrust force) of the boat is determined solely by the amount of water jetted backward from the jet nozzle at the rear end of the water jet pump and its jet speed. .
Therefore, if a jet-propelled planing boat with higher thrust force is desired, increase the engine horsepower and increase the cross-sectional area of the water jet pump or use the same cross-sectional area. For this, it is necessary to increase the rotation speed of the impeller to increase the water flow speed, particularly the speed of water sprayed backward from the spray nozzle.
[0005]
When the thrust force is increased by increasing the rotation speed of the impeller, the rotation speed cannot be increased beyond a certain level due to cavitation generated in the impeller portion.
[0006]
Therefore, in general, when a jet propulsion type personal watercraft having a larger thrust force is desired, it is often performed by increasing the water flow cross section of the water jet pump.
[0007]
However, for example, when trying to obtain a water jet pump whose thrust force is 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 prepare a mold for the water jet pump and the like, so that much labor and cost are required.
[0008]
The present invention has been made in view of such a situation, and can be simplified by utilizing the negative pressure of the water passage generated by the water jet pump without increasing the water cross section of the water jet pump itself. The purpose is to provide a jet propulsion planing boat with increased thrust force.
[0009]
[Means for Solving the Problems]
The present invention can solve the above problems by a jet propulsion type personal watercraft having the following configuration. That is,
A jet propulsion personal watercraft according to the present invention includes a water jet pump having an engine disposed in an engine room and a water intake port that is driven by the engine and absorbs external water. In a jet propulsion planing boat configured to pressurize and accelerate, spray from the jet port at the rear end of the water jet pump, and propel by its reaction,
The rear end opened to the negative pressure region (referred to as a negative pressure region caused by water flow, also referred to as a water flow negative pressure region) in the vicinity of the water jet pump outlet, and the tip opened to the water. The bypass water passage is provided in parallel with the water suction passage of the water jet pump.
[0010]
Therefore, according to the jet propulsion type personal watercraft configured as described above, the rear end of the bypass water passage that is provided side by side is open to the negative pressure region of the water jet pump. Pressure is generated, and water can be sucked into the bypass water passage from the front end 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.
[0011]
Further, in the jet propulsion type personal watercraft, if the tip of the bypass water passage is open to the bottom surface of the boat, the configuration becomes simple.
[0012]
Further, in the jet propulsion type personal watercraft, if the tip of the bypass water passage opens to the inside of the water inlet that has entered the wake side from the water inlet of the boat, the water jet pressure of the water jet pump is positive. Since it is a part, coupled with the negative pressure at the rear end of the bypass water passage, more water can be passed through the bypass water passage and a greater thrust force can be obtained.
[0013]
Further, in the jet propulsion type personal watercraft, if the tip of the bypass water passage is inclined in a direction deviating toward the rear of the boat as it goes to the downstream side, It becomes a structure that can be actively passed through the bypass waterway.
[0014]
Further, in the jet propulsion type personal watercraft, the rear end of the bypass water passage is opened on the casing wall surface of the portion where the water cross-sectional area behind the injection nozzle of the water jet pump is increased. A configuration capable of forming a negative pressure at the rear end of the water channel can be realized.
[0015]
Further, in the jet propulsion type personal watercraft, if the rear end portion of the bypass water passage is inclined in a direction deviating toward the rear side of the boat as it goes to the wake side, the jet nozzle makes a jet. Since a vector in the same direction as the direction of the water to be generated is generated in the water discharged from the bypass passage, more water can be passed through the bypass passage, and a larger thrust force can be obtained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a jet propulsion personal watercraft according to an embodiment of the present invention will be specifically described with reference to the drawings, taking a small personal watercraft as an example.
[0017]
FIG. 1 is a partial sectional view in the vicinity of a water jet pump of a boat showing a bypass water passage arranged in parallel with a water jet pump of a personal watercraft according to an embodiment of the present invention, and FIG. 2 includes the bypass water passage shown in FIG. FIG. 3 is an overall plan view of the small planing boat shown in FIG. 2.
[0018]
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 a connection line connecting the hull H and the deck D all around is called a gunnel line G. In this embodiment, the gunnel line G is located above the waterline L of the personal watercraft.
[0019]
As shown in FIG. 3, a substantially rectangular opening 16 extending in the longitudinal direction is formed on the upper surface of the hull A in the plan view slightly behind the center of the deck D, and is shown in FIGS. Thus, a seat S for riding is disposed above the opening 16.
[0020]
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 is mounted so that the crankshaft 26 is along the longitudinal direction of the hull A as shown in FIG. The output end of the crankshaft 26 is connected to the pump shaft 21S side of the water jet pump P, to which the impeller 21 is attached, via a propeller shaft 27 so as to be integrally rotatable. The outer periphery of the impeller 21 is covered with a pump casing 21C. Water taken from the water inlet 17 provided on the bottom surface of the small planing boat is taken in via the water suction passage and is added by the water jet pump P. It is configured to obtain a propulsive force through pressure / acceleration and discharge from the rear end injection port 21K through a pump nozzle (spout part) 21R whose water flow cross-sectional area becomes smaller as it goes backward.
[0021]
In FIG. 2, 21V is a stationary blade for rectifying the water passing through the water jet pump P. 2 and 3, a steering handle 24 is a steering operation means. By operating the handle 24 left and right, the steering nozzle 18 behind the pump nozzle 21R is swung left and right. When the water jet pump P is in operation, the boat can be steered in a desired direction. A throttle lever Lt for controlling the rotational speed of the engine E is disposed in the vicinity of the grip on the right side of the handle 24.
[0022]
As shown in FIG. 2, a bowl-shaped reverse deflector 19 is disposed above and behind the steering nozzle 18 so as to be swingable downward about a horizontally disposed swing shaft 19a. The deflector 19 is configured to swing backward to a lower position behind the steering nozzle 18 so that water discharged rearward from the steering nozzle 18 can be turned forward to move backward.
[0023]
2 and 3, reference numeral 22 denotes a rear deck. The rear deck 22 is provided with an openable / closable hatch cover 29, and a small capacity storage box (not shown) is formed below the hatch cover 29. Has been. 2 or 3, reference numeral 23 denotes a front hatch cover, and a box (not shown) for storing equipment and the like is provided below the hatch cover 23.
[0024]
By the way, in the personal watercraft according to the embodiment of the present invention, bypass water passages 1A and 1B as shown in FIGS. 1 and 2 are arranged in parallel to the water absorption passage P1 of the water jet pump P.
The tip 1a of the bypass water passage 1A opens into the water inlet 17 where the tip enters the wake side slightly from the water inlet 17 of the boat, as shown in an enlarged view in FIG. The rear end 1b of the bypass water passage 1A is formed on the casing wall surface of the portion 21N of the water jet pump P where the water passage cross-sectional area increases behind the injection port 21K. It opens toward the water passage Ps.
Further, as shown in the enlarged view of FIG. 1, the bypass water passage 1 </ b> B has a front end 1 d opened on the bottom surface Bf of the boat spaced rearward from the water inlet 17 of the boat. The rear end 1e of the bypass water passage 1B is formed on the casing wall surface of the portion 21N of the water jet pump P where the water passage cross-sectional area is increased, which is the water negative pressure region. It opens toward the water passage Ps.
Further, as shown in FIG. 1, the tip end portion 1T of the bypass water passages 1A and 1B is inclined in such a direction as to deviate toward the rear of the boat as it moves toward the wake side, and the boat advances. When it is, a positive pressure is generated in the opening at the tip.
Further, the rear end portions 1E of the bypass water passages 1A and 1B are inclined in a direction such that the rear end portions 1E are displaced toward the rear of the boat as they move toward the wake side, and the direction of water injected from the injection nozzle 21R A vector in the same direction is configured to be generated in the water discharged from the bypass passage.
[0025]
Thus, according to the jet propulsion type personal watercraft configured as described above, when the water jet pump P is operated, the following effects are exhibited. That is, when the water jet pump P is operated to suck in external water from the water suction port 17, and when the water jet pump P is pressurized and accelerated and sprayed from the rear jet port 21K, the bypass water passages 1A, 1B A negative pressure acts on each rear end opening. For this reason, each bypass water passage 1A, 1B sucks external water from the openings 1a, 1d at the tip, and draws water from the openings 1b, 1e at the rear end formed at the rear of the injection port 21K of the water jet pump P, respectively. Erupts.
In particular, the front end 1a of the bypass water passage 1A is open to the inside of the water inlet 17, and the front end 1N is inclined in a direction deviating toward the rear of the boat as it goes to the rear stream side as described above. For this reason, when the boat advances, water is actively passed (absorbed) from the front to the bypass water passage 1A.
Thus, in the case of the jet propulsion type personal watercraft according to the present embodiment, in addition to the water jetted through the water absorption path P1 of the water jet pump P itself, external water is also supplied from the bypass water passages 1A and 1B. Since the air is sucked and sprayed backward, a large thrust force that contributes to the forward movement of the boat can be obtained without increasing the cross-sectional area of the water jet pump P itself.
[0026]
【The invention's effect】
According to the present invention, external water is passed through the bypass water passage by using the negative pressure generated behind the water jet pump outlet without increasing the water flow cross section of the water jet pump itself. Thus, a greater thrust force can be obtained.
[0027]
Therefore, it is not necessary to design a new water jet pump even when trying to obtain a large thrust force, and a mold for each component (poi casing, impeller, etc.) of the new water jet pump is separately prepared. There is no need.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view in the vicinity of a water jet pump of a boat showing a bypass water passage arranged in parallel with the water jet pump of the personal watercraft according to the embodiment of the present invention.
2 is an overall side view of a personal watercraft equipped with a bypass water passage shown in FIG. 1. FIG.
3 is an overall plan view of the personal watercraft shown in FIG. 2. FIG.
[Explanation of symbols]
P …… Water jet pump P1 …… Water intake channel 1A …… Bypass water channel 1B …… Bypass water channel 1a, 1d …… Front end 1b, 1d …… Rear end 2E …… Exhaust outlet 21K …… Injection port

Claims (6)

A water jet pump that is driven by this engine and has a water intake port that absorbs external water, pressurizes and accelerates the water sucked from the water intake port, and the water jet pump In a jet-propelled planing boat that is configured to inject from the rear-end injection port and propel by its reaction,
A jet propulsion characterized in that a bypass water passage having a rear end opened in a negative pressure region in the vicinity of an injection port of the water jet pump and a front end opened in water is provided in parallel with the water suction passage of the water jet pump. Type planing boat. The jet propulsion type personal watercraft according to claim 1, wherein a tip of the bypass water passage is open to a bottom surface of the boat. 2. The jet propulsion type personal watercraft according to claim 1, wherein a tip of the bypass water passage opens to the inside of the water inlet that enters the downstream side from the water inlet of the boat. The jet propulsion planing boat according to claim 2 or 3, wherein a tip portion of the bypass water passage is inclined in such a direction as to deviate toward the rear of the boat as it goes to the wake side. . The rear end of the bypass water passage is open to a casing wall surface of a portion where a water passage cross-sectional area behind the injection nozzle of the water jet pump is increased. Jet-propelled planing boat described in 1. 6. The jet propulsion type personal watercraft according to claim 5, wherein a rear end portion of the bypass water passage is inclined in a direction such that the rear end portion of the bypass water passage is displaced toward the rear side of the boat.

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