JP4343392B2 - Intake structure of small planing boat engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an intake structure for a small planing boat engine such as a water bike.
[0002]
[Prior art]
The personal watercraft is provided with a jet propulsion device that generates water required by injecting water sucked from a suction opening that opens to the bottom of the ship, and an engine that drives the jet propulsion device. This small planing boat has a seat on the upper surface of the center part in the longitudinal direction of the hull, and the engine is mounted on the lower part of the seat. Due to space constraints that are narrow in the width direction, the crankshaft is arranged in the longitudinal direction and multiple cylinders are arranged in the longitudinal direction. An in-line multi-cylinder engine in parallel is installed. As this engine, a two-cycle engine that is usually small and provides high output is used, but in order to improve fuel efficiency, exhaust gas purification, controllability of engine operation, etc., a fuel injection type with an injector installed in the intake pipe The use of a 4-cycle engine is also considered.
[0003]
Japanese Patent Application Laid-Open No. 11-247463 discloses an intake device for a small vessel equipped with such a 4-cycle engine.
The intake system of this engine includes an intake manifold that communicates with the intake port of the cylinder head, a throttle body that is connected to the intake manifold, an intake box (intake chamber) that communicates with the throttle body via an intake pipe, An intake duct is connected to the intake box and has an air intake port (intake port) at the end. The intake chamber is formed in a box shape that is long in the front-rear direction along the cylinder side surface of the multi-cylinder engine arranged in parallel in the front-rear direction, and an intake duct is connected to the front wall thereof. The air intake of the intake duct is disposed above the flywheel case at the front end of the engine. As a result, when the hull overturns or rolls over, the flywheel case serves as a shield to the air intake and prevents water from entering the intake duct.
[0004]
[Problems to be solved by the invention]
However, in the intake device structure described in the above publication, since the intake air of the intake duct is provided at a position close to the front of the engine above the flywheel case, the intake air temperature increases, the intake charging efficiency decreases, and the output decreases. And air-fuel ratio control accuracy deteriorates. In this case, if the cooling means is provided in the intake system, the structure becomes complicated, and it is not preferable to dispose the cooling means in a narrow space such as a small planing boat because space restrictions on other devices become large.
[0005]
In addition, it is desirable that the engine noise be as small as possible. Therefore, there is a demand for reducing the noise by increasing the length of the intake passage and the capacity of the intake passage including the intake box.
The present invention takes the above-described conventional technology into consideration, and an object thereof is to provide an intake structure for a personal watercraft that can introduce low-temperature air and reduce noise with a simple configuration.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, an in-line multi-cylinder engine having a seat on the upper surface of a substantially central portion in the front-rear direction of the hull and a crankshaft arranged in the front-rear direction in the hull below the seat is mounted. In the intake structure of a small planing boat engine in which the air intake ports of the intake passages of the cylinders arranged in the front-rear direction along the front and rear are extended in the front-rear direction above the engine, and the intake box An air intake duct facing the air intake port and having an air intake in front of the engine is connected to the upper surface side of the air intake box through a communication hole on the air intake box upper surface. Open in one half of the hull in the left-right direction, and a filter unit is mounted in the other half of the intake box. The communication hole is formed in the portion surrounded by the filter element of the filter unit, the intake duct provides an air intake structure for a small watercraft engine, characterized in that it extends forward from the communication hole .
[0007]
According to this configuration, the intake box is provided above the engine, which is a heating element, the intake duct is connected to the upper surface thereof, and the air intake of the intake duct is provided in front of the engine. The low-temperature air can be sucked and sucked into the intake box while suppressing the thermal effect through the communication hole on the upper surface side of the intake box that is away from the engine. Further, when the ship rolls over, the front side of the hull floats up because it is light, and an air intake port of the intake duct is provided in front of the engine on the front side of the hull, so that it is difficult for water to enter. Further, since the intake passage is lengthened by the intake duct, intake noise is reduced.
[0008]
In a preferred configuration example, the intake duct has a flat cross-sectional shape whose height dimension is smaller than the width dimension.
[0009]
According to this configuration, it is possible to arrange the intake duct in a compact manner together with the intake box in a narrow space below the seat while suppressing the height of the intake duct provided above the engine.
[0010]
In a further preferred configuration example, one or more communication holes are formed in the vicinity of the central portion in the front-rear direction of the intake box.
[0011]
According to this configuration, since the intake air from the intake duct is introduced into the substantially central portion of the intake box, the air intake ports of the throttle bodies arranged in the front-rear direction in the intake box are substantially evenly distributed. Intake air is supplied, and air-fuel ratio control with high reliability is performed with stable uniform combustion.
[0012]
In a further preferred configuration example, the intake box includes an upper case and a lower case, and an opening is formed on the bottom surface of the lower case, and the opening is covered with a detachable bottom plate.
[0013]
According to this configuration, the upper surface of the engine is exposed from the opening of the lower case by removing the upper case of the intake box attached above the engine and removing the bottom plate of the lower case. Inspection and replacement can be performed, and maintenance workability is improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 and 2 are a side view and a plan view of a personal watercraft according to an embodiment of the present invention, respectively.
This personal watercraft 1 includes a seat 3 on the upper surface of a substantially central portion in the front-rear direction of a hull 2, and an in-line four-cylinder four-cycle engine 4 is mounted in the lower hull. A fuel tank 5 is mounted in front of the engine 4. The hull 2 is covered with a hull cover 7 having a hatch cover 6. A handle 8 is provided in front of the seat 3. A storage box 9 is provided in the hull behind the seat 3. Steps 10 are formed on the hulls 2 on the left and right sides of the seat 3. A ventilation hose 11 for taking outside air into the hull and ventilating is provided at the upper part of the hull on the front side of the handle 8.
[0015]
In order to obtain a predetermined exhaust passage length, the engine 4 is provided with an exhaust pipe 12 that is taken out from the right side of the engine, passes around the front surface, passes through the left side, and is arranged rearward. The crankshaft 13 of the engine 4 is disposed in the hull longitudinal direction, and an impeller shaft 15 is connected to a rear end portion thereof via a coupling 14. A jet propulsion unit 16 is attached to the rear end portion of the impeller shaft 15, and jet water flow is ejected through a steering nozzle 17 that is linked to the handle 8.
[0016]
An intake box 18 is provided above the engine 4. In the intake box 18, air intake ports 19 of the throttle bodies of the four cylinders arranged in the front-rear direction are arranged. An intake duct 20 is provided on the upper surface of the intake box 18. An air intake 21 that opens near the upper portion of the fuel tank 5 in front of the engine 4 is formed at the end of the intake duct 20. The intake duct 20 communicates with the inside of the intake box 18 through a communication hole 22 (FIG. 2) provided in the substantially central portion in the front-rear direction of the upper surface of the intake box 18.
[0017]
The intake box 18 of the present invention is provided above the engine 4. Here, the upper side of the engine includes not only the upper part of the cylinder head but also the cylinder side surface part on the upper side of the crankcase when the cylinder is arranged vertically or inclined on the upper side of the crankcase. For example, in the case of a two-cycle engine, a cylinder is disposed obliquely on the upper side of the crankcase, and an intake passage communicating with the crankcase is formed substantially perpendicularly adjacent to the cylinder. An air intake box can be provided.
[0018]
The engine 4 has a flywheel cover 50 protruding from the front surface 4a of the main body. The air intake 21 of the intake duct 20 of the present invention is disposed in front of the engine 4. Here, the front of the engine 4 is the front side of the front surface 4a of the main body, and preferably the front side of the front end of the flywheel cover 50. When the exhaust pipe 12 surrounds the engine front side as in the present embodiment, the front side of the exhaust pipe 12 is more preferable. In other words, it is desirable that the air intake port of the intake duct is disposed as far as possible from the engine so as not to excessively increase the intake resistance. By taking in the intake air from the front of the engine in this way, it is possible to take in low-temperature air with a small thermal influence from the engine. This also lengthens the intake passage and reduces noise.
[0019]
3 is a longitudinal cross-sectional view in the hull width direction of the intake box according to the present invention as viewed from the rear , FIG. 4 is a plan view thereof, and FIG. 5 is a longitudinal cross-sectional view in the front-rear direction. The intake box 18 is formed by an upper case 23 and a lower case 24. The upper and lower cases 23 and 24 are detachably coupled via eight coupling pieces 25 (FIG. 4). Bosses 26 and 27 that are abutted against each other at two central portions of the inner surfaces of the upper and lower cases 23 and 24 protrude to increase the coupling strength between the cases.
[0020]
A filter unit 28 is mounted between the upper case 23 and the lower case 24 via upper and lower sealing materials 29 in the substantially right half of the intake box 18. The right half of the intake box 18 constitutes one half in the left-right direction referred to in the present invention. The filter unit 28 includes a filter element 31 held by upper and lower support frames 30 and a bottom plate 49 that is integral with the lower support frame 30. The filter element 31 is a water separation filter that allows air to pass therethrough and prevents water from passing therethrough. In order to allow water accumulated inside the filter element 31 to escape, a drain hole (not shown) is formed at an appropriate position of the bottom plate 49. An opening 32 is formed in the lower case 24 where the filter unit 28 is mounted. When the upper case 23 is removed and the filter unit 28 is removed together with the bottom plate 49, the engine 4 is exposed through the opening 32 as shown in FIG.
[0021]
A four-cylinder throttle body 33 is arranged in the front-rear direction in a substantially left half of the intake box 18. The left half of the intake box 18 constitutes the other half in the left-right direction referred to in the present invention. An intake pipe 51 is connected to each throttle body 33, and an air suction port 19 at the tip thereof opens into the box. Each throttle body 33 is provided with a throttle valve 35, and an injector 36 is mounted downstream thereof. Each throttle body 33 is connected to an intake manifold 37 that communicates with an intake port 37a of the cylinder head. An intake valve 38 is provided at the end of the intake port 37a.
[0022]
The intake passage constituting the engine intake system includes an intake manifold 37 communicating with an intake port 37a, a throttle body 33 connected thereto, and an intake pipe 51 connected to the throttle body 33. The intake air is introduced from an air intake port 19 at the end of the intake pipe that opens into the intake box 18.
[0023]
The exhaust pipe 12 (FIGS. 1 and 2) is connected to a manifold 39 that communicates with the exhaust port 39a. An exhaust valve 40 is provided at the end of the exhaust port 39a. Each intake valve 38 and exhaust valve 40 are driven by a cam 42 mounted on a cam shaft 41. A cam sprocket 44 connected to the crankshaft 13 via a chain 43 is attached to the camshaft 41, and the cam 42 is driven to open and close the intake valves 38 and the exhaust valves 40 in synchronization with the crankshaft 13. .
[0024]
An intake duct 20 having a flat cross-sectional shape is attached to the upper surface on the right half side of the intake box 18 via a rubber seal 45. The intake duct 20 includes a connection duct portion 20a to the intake box 18 and an extension portion 20b coupled thereto. The end of the extension 20b of the intake duct 20 opens to the upper part of the fuel tank 5 in front of the engine to form an air intake 21 as shown in FIG.
The intake duct 20 may be integrally formed with the intake box 18.
[0025]
A communication hole 22 that communicates with the connection duct portion 20a of the intake duct 20 is formed at a substantially central portion of a portion surrounded by the filter element 31 of the upper case 23 of the intake box 18. Outside air is introduced almost uniformly into the intake box 18 from the communication hole 22, and water is separated by a filter and sucked into each throttle body 33. A plurality of communication holes 22 may be provided in the front-rear direction. Thus, the intake air is supplied to each throttle body 33 more uniformly. When multiple communication holes are provided, air is more likely to be sucked into the front hole, so the diameter of the rear communication hole is larger than the diameter of the front communication hole, and air is sucked uniformly into the intake box in the front-rear direction. You may comprise. Or you may form so that a long hole may be provided in the front-back direction and the width | variety may become wide toward the back side.
[0026]
FIG. 6 shows the lower case 24 with the upper case 23 and the filter unit 28 removed from the intake box 18.
As illustrated, the spark plug 46 of the lower engine 4 (FIG. 1) is exposed from the opening 32 on the bottom surface of the lower case 24. A throttle body 33 and an injector 36 are disposed in the lower case 24 adjacent to the opening 32. 47 is a fuel rail, and 48 is a throttle valve shaft. Thus, by removing the upper case 23 and the filter unit 28 together with the bottom plate 49 (FIGS. 3 and 5), the intake system parts of the engine such as the throttle body 33 and the injector 36 are exposed, and the ignition plug is passed through the opening 32. Since 46 is exposed, each part can be easily inspected and replaced.
[0027]
【The invention's effect】
As described above, in the present invention, a small planing boat whose space is limited because the intake box is compactly provided above the engine, the intake duct is connected to the upper surface, and the air intake is provided in front of the engine. However, the intake box and the intake duct are efficiently arranged in a narrow space, and low-temperature air is taken in from a position where the thermal influence from the engine is small, and this is taken into the intake system from the upper side of the intake box where the thermal influence of the engine is small It is possible to suppress the intake air temperature rise. Thereby, the charging efficiency of intake air is increased, and the output is improved. In addition, the intake duct extends long forward, increasing the volume of the entire intake passage and reducing intake noise.
[0028]
Further, when the ship rolls over, the front side of the hull floats up because it is light, and an air intake port of the intake duct is provided in front of the engine on the front side of the hull, so that a structure in which water does not easily enter is obtained.
[Brief description of the drawings]
FIG. 1 is a side view of a personal watercraft to which the present invention is applied.
2 is a plan view of the personal watercraft of FIG. 1. FIG.
FIG. 3 is a longitudinal sectional view of the intake structure according to the present invention in the ship width direction.
4 is a horizontal sectional view of the intake structure of FIG. 3;
5 is a longitudinal sectional view of the intake structure of FIG. 3 in the front-rear direction.
6 is a plan view of a lower case of the intake structure of FIG. 3. FIG.
[Explanation of symbols]
1: small planing boat, 2: hull, 3: seat, 4: engine, 5: fuel tank,
6: hatch cover, 7: hull cover, 8: handle, 9: storage box,
10: Step on foot, 11: Ventilation hose, 12: Exhaust pipe,
13: Crankshaft, 14: Coupling, 15: Impeller shaft,
16: Jet propulsion machine, 17: Steering nozzle, 18: Intake box,
19: Air intake port, 20: Air intake duct, 21: Air intake port, 22: Communication hole,
23: upper case, 24: lower case, 25: coupling piece, 26, 27: boss,
28: Filter unit, 29: Sealing material, 30: Support material,
31: filter element, 32: opening, 33: throttle body,
35: Throttle valve, 36: Injector
37: intake manifold, 37a: intake port, 38: intake valve,
39: Exhaust manifold, 39a: Exhaust port, 40: Exhaust valve, 41: Cam shaft,
42: cam, 43: chain, 44: cam sprocket, 45: rubber seal,
46: spark plug, 47: fuel rail, 48: throttle valve shaft, 49: bottom plate,
50: Flywheel cover, 51: Intake pipe.

Claims (4)

An in-line multi-cylinder engine equipped with a seat in the upper surface of the center in the longitudinal direction of the hull, with a crankshaft disposed in the longitudinal direction in the hull under the seat, and the intake air of each cylinder lined up in the longitudinal direction along the side of the engine In the intake structure of a small planing boat engine where the air inlet of the passage opens,
An air intake box is extended in the front-rear direction above the engine, the air intake port faces the air intake box, and an air intake duct having an air intake port in front of the engine is connected through a communication hole on the upper surface of the air intake box. Connected to the upper surface of the intake box ,
The air intake port opens in one half of the left and right direction of the hull in the intake box,
A filter unit is mounted in the other half of the intake box,
The communication hole is formed in a portion surrounded by the filter element of the filter unit at the upper part of the intake box,
The intake structure for a small planing boat engine, wherein the intake duct extends forward from the communication hole .   The intake structure for an engine for a personal watercraft according to claim 1, wherein the intake duct has a flat cross-sectional shape with a height dimension smaller than a width dimension.   3. The intake structure for a small planing boat engine according to claim 1, wherein one or two or more communication holes are formed in the vicinity of a central portion in the front-rear direction of the intake box.   The small size according to claim 1, 2 or 3, wherein the intake box comprises an upper case and a lower case, an opening is formed in a bottom surface of the lower case, and the opening is covered with a detachable bottom plate. Intake structure of a planing boat engine.

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