JP3156080B2 - Exhaust system for personal watercraft - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust system for a personal watercraft equipped with a water jet propulsion device.

[Prior Art] For example, in a personal watercraft, an engine of a water jet propulsion device is disposed inside a hull, an exhaust passage connected to the engine is located underwater, and exhaust gas is exhausted into water to produce exhaust noise. There is a thing which reduces. In such a personal watercraft, in order to further reduce the exhaust sound of the engine,
For example, a muffler is provided in an exhaust passage or a water lock having a silencing effect is provided to reduce the exhaust sound.

[Problems to be Solved by the Invention] However, especially in a personal watercraft, since the space inside the hull is limited, the size of a water lock or the like is limited, and there is a limit in reducing exhaust noise. For this reason, it is conceivable that the exhaust passage is opened in the water to exhaust the water. However, simply opening the exhaust passage in the water may increase the back pressure and reduce the output of the engine.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an exhaust device for a personal watercraft that can effectively reduce exhaust noise while maintaining the output of the engine.

[Means for Solving the Problems] In order to solve the problems and achieve the object, the present invention is configured as follows.

The invention according to claim 1 has a water injection unit driven by an engine while injecting water sucked from a water suction port by rotation of an impeller and driven by an engine. The bottom located at the center is recessed upward to form an outer hull recess, the water injection unit is arranged in the outer hull recess, and a bottom plate that covers below the water injection unit is provided. A personal watercraft that is attached to a hull by bolts and has a side bottom formed at a portion of the bottom near the outside of the bottom plate so as to be inclined upward as the distance from the bottom plate in the width direction of the hull increases. In the arrangement device, an exhaust passage from the engine is opened downward at a portion of the side hull bottom located rearward of an impeller of the water injection unit. Exhaust system for personal watercraft. ].

According to the first aspect of the present invention, the water jet unit is arranged in an outer hull recess formed by depressing the bottom of the hull located at the center in the hull width direction, and the hull is covered so as to cover below the water jet unit. At the part located outside the bottom plate attached to the hull bottom plate, there is formed a side bottom that is inclined so as to be located upward as it moves away from the bottom plate in the hull width direction.
Since the exhaust passage from the engine was opened downward,
Since the exhaust gas is discharged from the opening of the exhaust passage toward the water surface, the exhaust noise can be reduced,
This is convenient because it is not necessary to remove the exhaust passage when removing the bottom plate from the hull.

In opening the exhaust passage at the bottom of the hull facing downward, the exhaust passage was opened at the portion of the side hull located behind the impeller of the water injection unit. Even if the water is discharged toward the water injection unit, it is not sucked from the water injection port of the water injection unit, and the efficiency of the water injection unit can be maintained high.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side view showing a part of a personal watercraft to which the present invention is applied, FIG. 2 is a plan view showing a part of the personal watercraft which is broken, and FIG. 3 is a water jet propulsion device. FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, FIG. 5 is a sectional view taken along line VV of FIG. 3, and FIG. 6 is a schematic side view showing an exhaust device of the personal watercraft. .

In the figure, reference numeral 1 denotes a water jet propulsion device for a personal watercraft. A hull 2 has a central portion formed with a partition wall 3 for dividing the inside and outside of the hull 2. Further, at the rear of the hull 2, the bottom located at the center in the hull width direction is recessed upward to form a recess 4.
Is formed, and the water injection unit 11 is arranged in the concave portion 4,
The lower part of the water injection unit 11 is covered with a ship bottom plate 74.
Both sides of the recess 4 are filled with plastic foams 7, 8 inside the hulls 5, 6.

The hull 2 of the water jet propulsion device 1 is made of resin, an engine 10 is disposed in an interior 9 on the front side of the partition wall 3, and a water injection unit 11 is separately disposed in a recess 4 formed outside the hull at the bottom of the hull. Have been. Engine 10 and water injection unit
Both of the impellers 11 are connected by a power transmission shaft system 13 penetrating the partition wall 3. The hull 2 is provided with a seat 14 on which an occupant sits, a steering device 15 for steering, and the like.

The engine 10 is mounted on a bed 16 provided on the hull 2 with vibration isolating members.
The engine 10 is installed through a shaft 17 so that the vibration of the engine 10 is absorbed and the engine vibration is not transmitted to the hull 2. A fuel tank 18 is disposed in front of the engine 10, and fuel is injected from a cap 19 provided on the hull 2.

The exhaust passage 21a of the engine 10 is
The first exhaust expansion chamber 20 is connected to a first exhaust expansion chamber 20, and the exhaust gas is supplied from the first exhaust expansion chamber 20 to the starboard hull 2 via an exhaust passage 21 b made of a rubber elastic pipe. It is introduced into the expansion chamber 22. The exhaust passage 21b is connected to the first exhaust expansion chamber 4
After extending below 8, it passes through the front side of the engine 10 and is connected to the second exhaust expansion chamber 22. The second exhaust expansion chamber 22 also functions as a water lock chamber for preventing water entering from the main exhaust passage 23 from flowing back to the engine side. Since the first exhaust expansion chamber 20 and the second exhaust expansion chamber 22 are each long in the front-rear direction, a sufficient volume can be secured,
It is formed small in the lateral direction, giving the engine a compact size.

The main exhaust passage 23 connected to the second exhaust expansion chamber 22 is a partition 3
Extends obliquely rearward upward through the lower position of the hull 2 and further extends from the substantially central portion of the hull 2 toward the rear bottom, and exhaust gas is discharged from a main exhaust outlet 24 formed in the bottom of the rear portion of the hull 2 Exhaust. The main exhaust outlet 24 is connected to the water injection unit 11
It is located at the bottom of the ship behind the water injection port, and allows for smooth underwater discharge.

The angle of inclination of the main exhaust passage 23 with respect to the water surface of the main exhaust outlet 24 is smaller than the angle of inclination with respect to the water surface of the second exhaust expansion chamber 22 from the top 23a.

Downstream of the second exhaust expansion chamber 22, the top 23a of the main exhaust passage 23
A sub-exhaust passage 25 is branched from a further downstream side, and exhaust gas is supplied from the sub-exhaust passage 25 to a wall of a casing 26 of the water injection unit 11.
The air is exhausted into the exhaust expansion chamber 28 formed by the recess 27, the recess 4 and the water surface.

The exhaust expansion chamber 28 is located on the front side of the water injection unit 11, and the sub exhaust outlet 25a of the sub exhaust passage 25 is provided at a position above the water surface in the concave portion 4 at the rear of the hull from low to high speed. By providing the sub exhaust outlet 25a of the sub exhaust passage 25 in the concave portion 4 at the rear of the hull, the leakage of exhaust noise to the outside is reduced.

There is a gap between the wall 27 of the casing 26 and the bottom of the hull 2
29 is formed, the exhaust gas is throttled on the outer periphery of the casing 26, on the ship bottom and on the water surface to provide a noise reduction effect.

Further, the sub exhaust passage 25 is branched downstream of the second exhaust expansion chamber 22 and further downstream from the top 23 a of the main exhaust passage 23. The diameter of the sub-exhaust passage 25 is such that the back pressure at low speed is released, so that the exhaust noise can be prevented from increasing.

Further, a Helmholtz resonator 30 is connected to the main exhaust passage 23 downstream of the branch position of the sub exhaust passage 25 via a hose 30a. The exhaust noise can be further reduced.

The auxiliary exhaust passage 25 and the Helmholtz resonator 30 are connected to the main exhaust passage 23
By connecting to the downstream side from the top 23a of the watercraft, water entering from the auxiliary exhaust passage 25 and water accumulating in the Helmholtz resonator 30 when the personal watercraft falls down can be used to connect the water to the main exhaust passage 23 when the personal watercraft is erected. Outflow to the main exhaust outlet 24 side.

A steering nozzle 31 is provided at the rear of the water injection unit 11, and is steered in the left-right direction by a steering control cable 32 by operating the handle device 15. Further, the water injection unit 11 is connected to a cooling water intake hose 33 for sending cooling water to the engine 10, and is provided with a discharge pump 34 for discharging bilge water.

The engine 10 is arranged such that the crankshaft 35 is located in the front-rear direction of the hull 2. The input end of the power transmission shaft system 13 of the water injection unit 11 is elastically attached to the output shaft 35 a which is spline-engaged with the crankshaft 35. It is connected to.

The power transmission shaft system 13 includes an input shaft 36 that forms a front portion closer to the engine, and an impeller shaft 37 that forms a rear portion on the impeller coupling side. Input shaft 36 is the front bearing unit
The outer case 39 of the front bearing unit 38 is attached to the partition 3 of the hull 2 with bolts 40 and nuts 41. Outer case of front bearing unit 38
39 has a cover 42 attached with bolts 43, and this outer case 39
An anti-vibration member 45 is baked between the inner case 44 and the inner case 44. The input shaft 36 is rotatably provided on the inner case 44 via a bearing 46. Impeller side of inner case 44
44a is bent inward, and a sealing member 47 is provided on the engine side 44b.
Is provided.

The input shaft 36 is inserted into the hole 42a formed in the cover 42 of the front bearing unit 38 so as not to interfere with the input shaft 36, and a connecting shaft 48 is fixed to the front end of the input shaft 36. The flange portion 48a of the connecting shaft 48 is coupled to the flange portion 35b of the output shaft 35a, which is spline-engaged with the end of the crankshaft 35, via a rubber coupling 49, so that engine output can be obtained. .

In the water injection unit 11, the center of the impeller shaft 37 is a bearing 50.
, And a rear portion thereof is supported by a bearing 52 and a seal member 53, respectively. The impeller shaft 37 is provided with an impeller 54 for generating a thrust. The water injection unit 11 includes a suction casing 55 for introducing outside water to the impeller 54 side, an impeller duct 56 for accommodating the impeller 54 following the suction casing 55, and a fixed wing duct including a fixed wing 57 for following the impeller duct 56. 58, an injection duct 59 following the fixed wing duct 58, a steering nozzle 31 following the injection duct 59, and the like. The suction casing 55, the impeller duct 56, the fixed wing duct 58, and the injection duct 59 are connected to each other via a heating part, and are integrated by a through bolt (not shown) in this state.

The water injection unit 11 is disposed separately from the concave portion 4 of the hull 2, and a pair of right and left fixing legs 60 provided on the impeller duct 56 and the injection duct 59 are respectively provided on the hull 2 as vibration isolating members.
Tighten and fix with support bolts via 61. The fixing leg 60 is supported by the vibration isolating member 61 in a floating state so as not to directly contact the hull 2.

A shaft insertion portion 55a is formed in the suction casing 55, and the shaft insertion portion 55a is detachably inserted into an inner ring 68 that is a component of the front bearing unit. An O-ring 67 is arranged on the inner ring 68,
Water is prevented from entering the shaft insertion portion 55a through the insertion portion.

The shaft insertion portion 55a is loosely inserted into the opening 3a of the bulkhead 3, and the inner ring 68 projects forward from the opening 3a provided in the bulkhead 3 of the hull 2. Inner ring 68 and outer case 39
Between the outer ring 69 and the outer ring 69 press-fit
Is baked. Vibration of the water injection unit 11 is absorbed by the vibration isolating member 70 and restricted from being transmitted to the hull 2, and water is prevented from entering the front bearing unit 38.

Further, the suction casing 55 has a water suction port 55b and a water suction flow path 55c located on the front side of the impeller. Suction casing 5
The rear part of the front hull 71 is fixed to the hull 2 by bolts 72, and the front part is supported by the hull 2 by the vibration isolating member 73. The vibration isolator 73 absorbs the vibration of the water injection unit 11. The front boat plate 71 is formed of an aluminum plate, has a lattice-shaped screen 71a at the water suction port 55b of the suction casing 55, and can prevent foreign substances such as stones from entering.

The rear bottom plate 74 that covers the impeller duct 56, the fixed wing duct 58, the injection duct 59, and the steering nozzle 31 is formed of an aluminum plate, and the rear bottom plate 74 is fixed to the bottom of the ship with bolts 75.

The Helmholtz resonator 30 communicating with the main exhaust passage 23 can effectively reduce exhaust noise without affecting engine performance.

In addition, at low speed, air is exhausted from the sub-exhaust outlet 25a of the sub-exhaust passage 25 into the exhaust expansion chamber 28 of the concave portion 4, and the exhaust sound is less likely to leak outside. In addition, the sub exhaust outlet
By exhausting in the air from 25a, the back pressure of the exhaust system can be kept low, and it is possible to prevent engine malfunction at low speed.

On the other hand, when the personal watercraft is at high speed, the exhaust pressure of the engine 10 rises, the hull 2 rises, the water surface becomes as shown by the two-dot chain line in FIG. Exhaust. Further, since the main exhaust outlet 24 of the main exhaust passage 23 of the engine 10 is provided at the rear bottom of the ship, the exhaust does not enter the impeller 54 from the water suction port 55b, so that the performance may be reduced. Absent.

In addition, at this high speed, the main exhaust outlet of the main exhaust passage 23
Since the pressure of the water 24 is reduced by the water flow, the underwater exhaust gas is effectively exhausted, whereby the amount of air exhausted from the auxiliary exhaust outlet 25a is reduced, and the exhaust noise can be reduced.

In this manner, the water injection unit 11 is arranged in the outer hull recess 4 formed by recessing the bottom 2a located at the center in the hull width direction, and the hull is covered so as to cover below the water injection unit 11. A side bottom 100 is formed at a portion located on the outer side of the attached bottom plate 74 so as to be inclined upward so as to be away from the bottom plate 74 in the hull width direction.
Since the exhaust passage from the engine 10 is opened downward, the exhaust gas is discharged from the opening of the exhaust passage toward the water surface, so that the exhaust noise can be reduced and the ship bottom plate 74 is removed. It is convenient because it is not necessary to remove the exhaust passage when removing from the hull.

In opening the exhaust passage on the bottom 2a facing the lower part of the hull, the exhaust passage was opened in a portion of the side hull 100 located behind the impeller 54 of the water injection unit 11, so that the exhaust passage was exhausted from the exhaust passage. Even if the gas is discharged downward, the gas is not sucked from the injection water intake of the water injection unit 11, and the efficiency of the water injection unit 11 can be maintained high.

Then, when the personal watercraft falls, water is discharged from the main exhaust outlet 24 of the main exhaust passage 23 and the sub exhaust outlet 25a of the sub exhaust passage 25,
It may enter the main exhaust passage 23. By the way, when the top 23a of the main exhaust passage 23 and the Helmholtz resonator 30 fall down, the water that has entered the main exhaust passage 23 accumulates on the top 23a of the main exhaust passage 23 and the Helmholtz resonator 30.

When this downsized personal watercraft is erected, the water accumulated at the top 23a of the main exhaust passage 23 is removed from the top 23a of the main exhaust passage 23.
Therefore, the water accumulated in the Helmholtz resonator 30 is communicated downstream from the top 23a of the main exhaust passage 23, and flows out to the main exhaust outlet 24 side. The water that overflows from the Helmholtz resonator 30 and accumulates on the top 23a of the main exhaust passage 23 also forms the top 23a.
Since a large amount is accumulated on the side having a smaller inclination angle with respect to the water surface on the rear end side, a large amount flows out to the erecting main exhaust outlet 24 side.

In this manner, when the personal watercraft falls down, it is possible to prevent water that has entered from the outside from flowing back to the engine when the personal watercraft is erected. Further, even if the gas may flow from the main exhaust passage 23 to the engine side, the amount thereof can be reduced, and the second exhaust expansion chamber 22 is effectively prevented from flowing back to the engine side.

FIG. 7 is a schematic side view showing another embodiment of the exhaust device.

In this embodiment, nine Helmholtz resonators 300, 301, 302 having different capacities are connected via hoses 300a, 301a, 302a downstream of the second exhaust expansion chamber 22 and downstream of the top 23a of the main exhaust passage 23. is there. In this way, by connecting the Helmholtz resonators 300, 301, 302 having different volumes to the plurality of main exhaust passages 23, the range of noise frequencies at which noise can be reduced can be increased, and exhaust noise can be further reduced.

[Effects of the Invention] As described above, the present invention arranges a water injection unit in an outer hull recess formed by recessing a ship bottom located at a central portion in the hull width direction, and below the water injection unit. A portion of the bottom located outside the bottom plate attached to the hull so as to cover the bottom is formed with a side bottom which is inclined upward so as to be away from the bottom plate in the width direction of the hull.
Since the exhaust passage from the engine was opened downward,
Since the exhaust gas is discharged from the opening of the exhaust passage toward the water surface, the exhaust noise can be reduced,
This is convenient because it is not necessary to remove the exhaust passage when removing the bottom plate from the hull.

In opening the exhaust passage at the bottom of the hull facing downward, the exhaust passage was opened at the portion of the side hull located behind the impeller of the water injection unit. Even if the water is discharged toward the water injection unit, it is not sucked from the water injection port of the water injection unit, and the efficiency of the water injection unit can be maintained high.

[Brief description of the drawings]

FIG. 1 is a side view showing a part of a water jet propulsion device to which the present invention is applied, FIG. 2 is a plan view showing a part of a water jet propulsion device being cut away, and FIG. FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, FIG. 5 is a sectional view taken along line VV of FIG. 3, FIG. 6 is a schematic side view showing an exhaust device, FIG. The figure is a schematic side view showing another embodiment of the exhaust device. In the figure, 1 is a water jet propulsion device, 2 is a hull, 3 is a partition, 4 is a recess, 10 is an engine, 11 is a water injection unit, 12
Is an impeller, 13 is a power transmission shaft system, 21 is a first exhaust expansion chamber,
Reference numeral 22 denotes a second exhaust expansion chamber, 23 denotes a main exhaust passage, 24 denotes a main exhaust outlet, 25 denotes a sub exhaust passage, 25a denotes a sub exhaust outlet, 26 denotes a casing, and 30,300,301,302 denote Helmholtz resonators.

Claims (1)

(57) [Claims] 1. A water injection unit driven by an engine while injecting water sucked from a water suction port by rotation of an impeller and being driven by an engine. The water injection unit is located at a center of a hull width direction in a hull width direction. The hull bottom is depressed upward to form a hull recess, the water injection unit is disposed in the hull recess, a bottom plate is provided to cover the lower part of the water injection unit, and the bottom plate is attached to the hull by bolts. A device for arranging a small personal watercraft in which a portion located near the outside of the bottom plate of the bottom of the bottom has a side bottom that is inclined upward so as to be separated from the bottom plate in the width direction of the hull, An exhaust passage from the engine is opened downward at a portion of the side hull bottom located behind the impeller of the water injection unit. Planing boat exhaust system.