JP2002220092A - Small planing boat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small planing boat with a water-cooled muffler that can minimize the discharge of cooling water into the muffler and effectively lower the temperature of exhaust gas, in a jet-propelled type of small planing boat comprising an engine with a water-cooled muffler. SOLUTION: The jet-propelled small planing boat develops propulsion by reaction when a waterjet pump P driven by the engine E with the water-cooled muffler 2 into which cooling water is introduced jets pressurized and accelerated water from a rear jet 21K. A cooling jacket 6 of the water-cooled muffler 2 is extended longitudinally along the muffler 2, and at least two places in the upstream and the downstream along the length are provided with discharge openings 3A (3Au and 3Ad) through which cooling water in the cooling water chamber 6 is discharged into the muffler 2 or a downstream exhaust passage 8. In a relatively low speed range, the upstream discharge opening 3Au is opened, and in a higher speed range, the downstream discharge opening 3Au is opened.

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 Watercraft; PWC), which jets a stream of water backward and sails on the water in reaction to the jet. The present invention relates to a personal watercraft equipped with a muffler.

[0002]

2. Description of the Related Art In recent years, so-called jet propulsion type personal watercraft have been frequently used for leisure, sports, rescue, and the like. In this jet-propulsion type personal watercraft, water sucked from a water inlet provided on the bottom surface of the boat is pressurized and accelerated by a water jet pump, and the water is jetted rearward from the jet to propel the hull. .

[0003] In the personal watercraft described above, in order to lower the exhaust gas temperature of the engine and further reduce the exhaust noise,
Exhaust muffler (in this specification, simply "muffler"
In some cases, a "water-cooled muffler" is provided in which a discharge port for discharging cooling water into the muffler is provided, and cooling water is discharged from the discharge port into the muffler.

In the case of an engine equipped with this water-cooled muffler, if there is a large amount of cooling water discharged from the discharge port in a high-speed range, the back pressure (discharge pressure) of the engine increases, and the performance of the engine in a high-speed range Lower. On the other hand, if the amount of cooling water from the discharge port is too small, the exhaust gas temperature rises,
The replacement time of the rubber connection parts for connecting the muffler and the downstream water box is hastened.

In other words, from the viewpoint of the performance of the engine, in particular, the performance of the engine in the high-speed rotation range, it is preferable that the amount of the cooling water from the discharge port is small. If the amount is small, the replacement time of the connecting parts between the muffler and the water box will be advanced. For this reason, at present, it is impossible to reduce the discharge amount of the cooling water into the muffler.

The present invention has been made in view of the above circumstances, and in a jet-propulsion personal watercraft equipped with an engine having a water-cooled muffler, the amount of cooling water discharged into the muffler is reduced as much as possible. It is an object of the present invention to provide a personal watercraft equipped with a water-cooled muffler capable of effectively reducing the exhaust gas temperature.

[0007]

SUMMARY OF THE INVENTION A jet-propulsion personal watercraft according to the present invention is a water jet pump driven by an engine having a water-cooled muffler for introducing cooling water into a muffler. A jet propulsion type personal watercraft that injects discharged water from a rear injection port and propells by the recoil thereof, wherein a cooling jacket of the water-cooled muffler is provided on an outer periphery of a muffler of the muffler, and an upstream side of the cooling jacket. A discharge port for discharging cooling water from the cooling water chamber to the inside of the muffler or to the exhaust passage on the downstream side is provided at at least two places on the downstream side, and at least in the relatively low speed region, the discharge port on the upstream side is opened. In the high-speed range, the discharge port on the downstream side is opened.

Thus, according to the jet-propulsion personal watercraft equipped with the cooling type muffler configured as described above,
At a relatively low speed region, at least the discharge port on the upstream side is opened, and at a higher speed region, the discharge port on the downstream side is opened. The temperature can be efficiently reduced. For this reason, in the low-speed rotation region, since the volume of the muffler has a margin, the cooling water is discharged from at least the upstream discharge port which affects the volume of the muffler, while in the high-speed rotation region, the volume of the muffler is substantially reduced. It is configured to discharge the cooling water from the discharge port on the downstream side that has little effect on the reduction of the cooling water.

In the jet-propulsion personal watercraft, if the cooling jacket extends to the rear end of the muffler, the exhaust gas can be more effectively cooled in the muffler.

In the jet-propulsion personal watercraft, each of the discharge ports is provided with an opening / closing operation valve, and the opening / closing operation valve is operated in accordance with the number of revolutions of the engine. When configured to open and close,
In accordance with the engine speed, a water-cooled muffler that can automatically open the discharge port on the upstream side at a relatively low speed range and open the discharge port on the downstream side at a higher speed range It is possible to realize a jet-propulsion small personal watercraft equipped with the watercraft.

In the jet-propulsion personal watercraft, the opening / closing operation valve is a solenoid valve, and the solenoid valve is operated based on a signal from an engine speed detection sensor.
It can be configured to be opened and closed by an electric signal from the engine control unit.

Further, in the jet-propulsion personal watercraft, when the discharge port is formed on an upper wall surface of the muffler, a structure can be realized in which cooling water can be uniformly discharged to an exhaust gas passage. Can be.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a personal watercraft according to an embodiment of the present invention will be specifically described with reference to the drawings, taking a personal watercraft as an example.

FIG. 1 is a partially cutaway overall side view showing an exhaust system of a jet-propulsion personal watercraft equipped with a water-cooled muffler according to an embodiment of the present invention, and FIG. 2 is a jet-propulsion type watercraft shown in FIG. FIG. 3 is a partially cutaway plan view showing the exhaust system of the engine of the personal watercraft.
FIG. 4 is a partially enlarged side view of the entire exhaust system shown in FIG.
4A to 3C are enlarged views showing the configuration of the rear end of the water-cooled muffler shown in FIG. 3, wherein FIG.
IVb arrow view, FIG. 5 is a partial cross-sectional plan view partially showing the connection between the rear end of the water-cooled muffler and the water box on the downstream side, and FIGS. FIG. 2 is an overall side view and an overall plan view of the planing boat partially cut away.

In FIG. 9 or FIG. 10, 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 a gunnel line. G, and in this embodiment, the gunnel line G is located above the waterline L of the personal watercraft.

As shown in FIG. 10, a substantially rectangular opening 16 extending in the longitudinal direction on the upper surface of the hull A is formed slightly behind the center of the deck D, as shown in FIG. As shown in FIG.
A seat S for riding is arranged above.

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. The engine E is a multi-cylinder (three-cylinder in this embodiment) two-cycle type engine E.
As shown in FIG. 9, the crankshaft 10b is mounted in a direction along the longitudinal direction of the hull A,
The output end of the crankshaft 10b is integrally rotatably connected via a propeller (impeller) shaft 15 to the pump shaft side of a water jet pump P to which the impeller 21 is attached. And this impeller 2
1 has an outer periphery covered with a pump casing 21C, takes in water taken in from a water supply port 17 provided on the bottom surface of the personal watercraft via a water absorption path, and pressurizes and accelerates the water jet pump P. And the pump nozzle (spouting part) 21 whose cross-sectional area of water has become smaller as it goes
It is configured so that it passes through R and is discharged from the rear end injection port 21K to obtain a propulsive force.

In FIG. 9, reference numeral 21V denotes a stationary blade for rectification. 9 and 10, reference numeral 10 denotes a steering bar-shaped handle serving as a steering means. By operating the handle 10 right and left, the pump nozzle 21R (injection) is steered through a steering cable 24. The mouth 21K) is configured so that the boat can be steered in a desired direction when the water jet pump P is operated by swinging the steering nozzle 18 at the rear side right and left. In FIG. 10, Lt indicates an operation lever of the throttle of the engine E attached to the handle 10.

9 and 10, reference numeral 12 denotes a rear deck. The rear deck 12 is provided with an openable / closable hatch cover 29, and a small-capacity storage box is formed below the hatch cover 29. I have. 9 and 10, 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.

The personal watercraft according to the embodiment of the present invention has an exhaust system Ex for discharging exhaust gas from the engine E, as shown in FIGS. The exhaust system Ex is connected to a water-cooled muffler 2 from each exhaust port of the engine E via an exhaust manifold 1 in the form of a collecting pipe. Also, the muffler 2
Is connected via a rubber connection pipe 11 to a water box 12 arranged on the downstream side. Further, the water box 12 is configured to discharge exhaust gas from the stern of the hull A to the outside via the exhaust tube 14.

As shown in FIG. 4 and FIG. 5, the rear end of the muffler 2 is for a two-cycle engine E in the present embodiment, and is intended to prevent air-fuel mixture from flowing through. The shape is narrowed (reduced in diameter) at the rear end. Almost the entire muffler 2 is formed of a double pipe. That is, the inner pipe 2A includes an inner pipe 2A through which exhaust gas passes, and an outer pipe 2B that covers the inner pipe 2A and flows cooling water between the inner pipe 2A. The inner tube 2A and the outer tube 2B are connected to the rear end of the outer tube 2B, and the rear end of a space (cooling jacket 6) formed between the inner tube 2A and the outer tube 2B is externally connected. A connecting wall 3 for isolation is formed. The connection wall 3 is disposed so as to be substantially orthogonal to the longitudinal direction of the muffler 2. The inner tube 2A
Extends from the rear end of the outer tube 2 </ b> B, which is most narrowed down, to the rear, with the same diameter, and extends rearward from the connection wall 3. In this embodiment, as described above, the cooling jacket 6 of the muffler 2 is extended to the rear end of the muffler 2 along the longitudinal direction of the muffler, and is provided at two locations on the upstream side and the downstream side in the longitudinal direction. An exhaust passage 8 from the cooling water chamber 6 into the muffler 2 or downstream thereof.
And discharge port 3A (in this embodiment "connection pipe 11") for introducing cooling water into (3A _u, 3A _d) a provided. Of course,
The discharge ports 3A may be provided at two or more places, for example, three places or more. The upstream discharge port 3A _u is
The muffler 2 is formed at a position on the upstream side of the narrowed shape (“cone shape”). In addition, the outlet 3A _d on the downstream side
The connection wall 3 located at the narrowed rear end of the muffler 2
Formed in the part.

The upstream discharge port 3A _u is formed at the upper end of the muffler 2 so as to face the center of the muffler 2 so as to pass through the inner tube 2A of the muffler 2 in the center direction.

On the other hand, the discharge port 3A on the downstream side _d is formed in the connecting wall 3 part of the upper end position of the muffler 2. Then, the discharge port 3A _d located the downstream side, on the outer peripheral surface of the inner tube 2A on the downstream side, the projections 4 to hinder the flow to the rear of the cooling water discharged from the discharge port 3A _d Are formed toward the outer diameter. As shown in FIG. 6, the height h of the projection 4 is formed slightly lower than the outer peripheral surface of the outer tube 2B. Further, the discharge port 3A _d of the downstream side,
As the virtual extension line Z illustrated by two-dot chain line in FIG. 4 (a), a virtual extension line Z of the discharge port 3A _d is formed obliquely upward to avoid the protrusion 4. The virtual extension line Z can be regarded as indicating a drill when drilling the discharge opening 3A _d (direction of the drill). Moreover, the projections 4 in the case of this embodiment, when viewed from above (plane), as shown in FIG. 5, such a part depicting a substantially arc centered on the discharge port 3A _d, ejection It is composed of songs walls as curved around the outlet 3A _d. In FIGS. 4 and 6, the surface of the inner tube 2A in front of the projection 4 is straight in this embodiment, but instead is directed toward the projection 4 as shown in FIG. It may be formed on a slope 5 that is gradually raised. In such a case, since the flow in the protrusion 4 side along the cooling water slope discharged from the discharge port 3A _d, the discharge port 3A _d itself may be provided horizontally.

The discharge ports 3A _{u and} 3A _d are provided with:
Each of the solenoid valves 7 is provided, and the ON-O
The FF operation, each outlet 3A _u, 3A _d is configured to be opened and closed.

As shown in the block diagram of FIG. 7, each of the solenoid valves 7 is connected to a control unit (engine control unit) Ec of the engine E. In the case of this embodiment, the engine control unit Ec detects the rotation speed of the engine E from the rotation speed detection sensor Er, and when the rotation speed of the engine is in a low rotation range, for example, 280 from the idling rotation speed.
Until 0rpm, each discharge port 3A u of two _positions, the respective solenoid valves 7 of 3A _d in the ON in the "open", for supplying cooling water into the muffler 2 both discharge port _3A, the 3A _d. On the other hand, when the rotation speed of the engine is in a high-speed rotation range, for example, 2800
In the above rpm, the electromagnetic valve 7 of the discharge port 3A _d on the downstream side O
In the N in the "open", and is configured to supply the cooling water from only the discharge port 3A _d of the wake side in the muffler 2.
In other words, in the low-speed rotation region, a large amount of cooling water is discharged because there is room in the volume of the muffler, whereas, in the high-speed rotation region, almost all of the volume of the muffler is required to function as a muffler. are configured only for discharging the cooling water from the discharge port 3A _d on the downstream side. In the high speed range, since the water jet pump P is rotated at high speed, more cooling water from the discharge port 3A _d than at low speed is discharged, also in the cooling effect is enhanced.

The engine control unit Ec is a control device for controlling the ignition timing and the fuel injection timing of the engine E to an optimum state in accordance with the rotation speed of the engine E and the like.

Thus, according to the jet-propulsion personal watercraft equipped with the water-cooled muffler, the following operations are performed. In other words, the high-temperature exhaust gas discharged from the exhaust port of the engine E passes through the exhaust manifold 1 and then enters the water-cooled muffler 2 arranged on the downstream side, and the outer periphery of the muffler 2 The cooling noise is reduced to some extent by the cooling jacket 6 formed in the portion, and the exhaust noise is reduced.

Next, from the rear end of the muffler 2 to the exhaust passage 8
In this embodiment, the exhaust gas (see the gray arrow Fg in FIGS. 5 and 6) discharged to the passage inside the connection pipe 11 is supplied to the control unit Ec when the engine E rotates at a high speed. but the solenoid valve of the discharge port 3A _d of the downstream side 7
The in the in the ON "open", and supplies the cooling water only from the discharge port 3A _d of the muffler 2 to the rear of the exhaust passage 8, the downstream side. That is, in the high speed range, the cooling water along the outer peripheral surface of the inner tube 2A from the discharge port 3A _d on the downstream side and flows out to the exhaust passage 8, intermingled exhaust gas directly (FIG. 5, FIG. 6 Exhaust gas is effectively cooled by the cooling water (see hatched arrow Fm). Specifically, as shown by an arrow Fw of white in FIG. 6 is a 5 and a side view is a plan view, the arrangement position of the discharge port 3A _d, by the arrangement of the projections 4 of the configuration of the subsequent downstream The cooling water is distributed evenly over the outer peripheral surface of the inner pipe 2A and flows from the entire circumference of the inner pipe 2A to the rear end of the inner pipe 2A, and the exhaust gas discharged from the inner pipe 2A to the exhaust passage 8 and the exhaust passage 8 (See hatched arrows Fm in FIGS. 5 and 6) as much as possible in the entire cross section of FIG. As described above, since the exhaust gas and the cooling water are evenly mixed in the entire peripheral area of the rear end of the inner pipe 2A, the exhaust gas is cooled very efficiently. hand,
It can be reduced significantly. In addition, the exhaust gas flows in the connection pipe 11 that has exited from the outlet of the muffler 2, that is, in the exhaust passage 8 (the connection pipe 11
In), since the cooling water is cooled, the amount of the cooling water can be reduced, and since the cooling water is introduced into the exhaust passage behind the muffler 2, the exhaust pressure of the engine E increases compared to the conventional one. And can be greatly reduced. As a result, the performance of the engine E in the high-speed rotation range is improved as compared with the conventional water-cooled muffler.

On the other hand, when the engine E
Means that the control unit Ec detects that the two
Exit 3A_u,3A_d Turn ON each solenoid valve 7 to open
And the two outlets 3A_u,3A_d From muffler 2
Cooling water to the exhaust passage 8 on the downstream side (the downstream side) of the muffler 2
Supply. In other words, in the low-speed rotation range,
3A_d Cooling water from the muffler 2
Supply to the downstream exhaust passage, and discharge upstream
Mouth 3A _u Supply cooling water into the muffler 2 and exhaust
The gas can be cooled. In this embodiment,
In the rotation range, two outlets 3A_u,3A_d Supply cooling water from
But the upstream side
Outlet 3A located_uCooling water may be supplied only from
No. In this case, a configuration that is easier to control
it can. As described above, the inside of the muffler 2 and the muffler
Exhaust gas efficiency at exit 2 or muffler 2
Because it is well cooled and the temperature of the exhaust gas drops,
Even if the connection pipe 11 is made of rubber, it is significantly deteriorated by heat.
And the replacement period can be set longer. Subordinate
Therefore, a rubber connection which is flexible and suitable as a connection member
Even if a tube is adopted, long-term replacement becomes unnecessary. Of course, on
The noise is reduced by mixing exhaust gas and cooling water directly.
The effect is also promoted.

[0030] In the above embodiment, an embodiment in which a protrusion 4 for evenly distributed on the outer circumferential surface of the inner tube 2A by the downstream side of the discharge port 3A _d on the downstream side has been described,
Even if a cooling pipe is formed between the rear end of the muffler and the cooling jacket without a projection, a large cooling effect and a reduction effect of exhaust pressure in the high-speed region can be achieved compared to the conventional water-cooled muffler. Is obtained. Alternatively, in addition to the configuration of the double pipe extending to the rear end, only the discharge port is provided on the connection wall that extends the inner pipe to the downstream side of the outer pipe and connects the inner pipe and the outer pipe. By providing such a structure, a large cooling effect and an effect of reducing exhaust pressure in a high-speed range can be obtained as compared with the conventional water-cooled muffler. In such a case, it is effective to provide a plurality of the discharge ports on the connection wall.

In addition, in the configuration shown in FIGS. 1 to 6, each of the upstream and downstream discharge ports may be provided in plural instead of one. In that case, the diameter of each discharge port may be reduced so that the entire amount of cooling water does not change.

In the above embodiment, the solenoid valves of the respective discharge ports are controlled based on the engine speed itself. However, the throttle opening of the engine and the injection of the water jet pump are proportional to the engine speed. Control may be performed by detecting changes in pressure, boat speed, etc. Needless to say, in such a case, control is performed based on the engine speed.

As shown in FIG. 8, the muffler 2
In addition to the discharge ports 3A _{U and} 3A _d , a cooling water discharge port 3B for discharging cooling water from the cooling jacket 6 is separately provided, and more cooling water than necessary is supplied from the cooling water discharge port 3B to the muffler 2. It may be configured to discharge to the outside. In such a case, an electromagnetic valve (not shown) is provided at the cooling water discharge port 3B, and this electromagnetic valve is controlled by the control unit Ec according to the engine speed, and is discharged according to the engine speed. It may be configured such that the amount of cooling water flowing out from the outlet 3A (3A _U, 3A _d ) can be adjusted.
That is, in the low-speed range of the engine, the cooling water discharge port 3B
, A larger amount of cooling water may be discharged from the fuel cell, and a smaller amount of cooling water may be discharged in a high speed region. In addition, the cooling water discharge port 3B is generally connected to the discharge port 3A (3A _U, 3A _d ).
Since the hole diameter is configured to be larger, it effectively functions as a configuration for discharging sand, pebbles, and the like that have entered the cooling jacket.

[0034]

According to the present invention, in a jet-propulsion personal watercraft equipped with an engine having a water-cooled muffler, the discharge amount of cooling water into the muffler is reduced as much as possible, and the exhaust gas is reduced. The temperature can be effectively reduced.

Accordingly, since the exhaust pressure is reduced as much as possible in both the high-speed range and the low-speed range of the engine, the personal watercraft can effectively utilize the potential performance of the engine.

[Brief description of the drawings]

FIG. 1 is an overall side view showing an exhaust system of a jet-propulsion personal watercraft equipped with a water-cooled muffler according to an embodiment of the present invention.

FIG. 2 is an overall plan view showing an exhaust system of an engine of the jet propulsion personal watercraft shown in FIG.

FIG. 3 is a side view showing an external shape of the exhaust system shown in FIGS. 1 and 2;

4 is an enlarged view showing a configuration of a rear end portion of the water-cooled muffler shown in FIGS. 1 to 3, (a) is a side sectional view, and (b) is (a).
IVb-IVb of FIG.

FIG. 5 is a partial plan sectional view showing a connection portion between a rear end portion of a water-cooled muffler and a water box on a downstream side of the muffler.

FIG. 6 is a partial side sectional view showing a connection portion between a rear end of a water-cooled muffler and a water box on a downstream side of the muffler.

FIG. 7 is a block diagram showing a configuration of controlling a solenoid valve of a discharge port arranged in the water-cooled muffler shown in FIGS. 3 to 6;

FIG. 8 is a partial side sectional view showing a configuration of a rear end of a water-cooled muffler according to another embodiment different from FIGS. 3 to 6;

FIG. 9 is a partially cutaway side view showing the entire configuration of a jet-propulsion personal watercraft having a water-cooled muffler according to the present invention.

10 is an overall plan view of the personal watercraft shown in FIG.

FIG. 11 is a partially enlarged side cross-sectional view showing a configuration of a discharge port and a protrusion behind the discharge port according to another embodiment.

[Explanation of symbols]

E ... Engine P ... Water jet pump 2 ... Muffler 3A (3A _U, 3A _d ) ... Discharge port 6 ... Cooling jacket 8 ... Exhaust passage 21K ... Injection port

Claims (5)

[Claims] 1. A water jet pump driven by an engine having a water-cooled muffler for introducing cooling water into a muffler, injects pressurized and accelerated water from a rear injection port, and propulses by the recoil thereof. A jet-propulsion personal watercraft, wherein a cooling jacket of the water-cooled muffler is provided on an outer periphery of the muffler, and at least two places on the upstream side and the downstream side of the cooling jacket, from the cooling water chamber to the muffler or thereafter. A discharge port for discharging cooling water is provided in the exhaust passage on the downstream side, and at least in the relatively low-speed region, the upstream-side discharge port is opened, and in the higher-speed region, the downstream-side discharge port is opened. A personal watercraft characterized by the above-mentioned. 2. The personal watercraft according to claim 1, wherein the cooling jacket extends to a rear end of the muffler. 3. An opening / closing operation valve is attached to each of the discharge ports, and the opening / closing operation valve is operated to open / close these discharge ports in accordance with the number of revolutions of the engine. The personal watercraft according to claim 1 or 2, wherein 4. The valve according to claim 1, wherein the on-off control valve is an electromagnetic valve, and the electromagnetic valve is opened and closed by an electric signal from an engine control unit based on a signal from an engine speed detection sensor. Item 4. The personal watercraft according to item 2 or 3. 5. The personal watercraft according to claim 1, wherein the discharge port is formed on an upper wall surface of the muffler.