JP2001199380A - Structure of four-stroke engine for snowmobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a four-stroke engine for snowmobile having a starter motor and reducing occupying space. SOLUTION: This is a four-stroke engine 2 with a cylinder head 3 arranged on the upper side. In an engine room 6 formed at the front of the vehicle body of snowmobile 1, the main body of the engine 2 is located to incline toward the vehicle-body advancing direction with a crankshaft 7 almost parallel to vehicle-body lateral direction. One end 7a of the crankshaft 7 is provided with a flywheel 54, and a centrifugal clutch 55 is provided on the outside of the flywheel 54. The other end 7b of the crankshaft 7 is provided with an auxiliary equipment driving pulley 63, and an alternator 51 is arranged on the pulley 63 side of the upper-side part of the inclined main body of the engine 2. A starter motor 60 is arranged on the flywheel 54 side of the upper-side part of the main body of the engine 2, and an intake pipe 40 is arranged above the starter motor 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an engine, and more particularly to a structure of a four-stroke engine mounted on a snowmobile.

[0002]

2. Description of the Related Art Conventionally, a two-stroke engine is generally used as an engine of a small snowmobile such as a snowmobile. As a feature of the two-stroke engine, there are advantages that the engine structure is relatively simple, lightweight, compact and high power. However, compared with a four-stroke engine, there is a problem that the amount of exhaust gas emission is large, noise is large, and vibration is large. A recent global trend has been the need for clean, quiet and environmentally friendly engines. Snowmobile engines are no exception, and there is a demand for a clean and quiet engine. Therefore, a four-cycle snowmobile engine is being studied.

[0003] Conventional snowmobiles 100 generally include:
As shown in FIG. 5, the frame 110 of the vehicle body has a monocoque frame structure, and the engine 10 is provided in a space between a track housing 111c and a front suspension housing 111b formed on the entire frame 111.
In the case of a two-cycle engine, the engine 102 is mounted upright in the engine room 106.

[0004]

If a four-stroke engine is to be mounted on a snowmobile in the same manner,
As compared with a two-stroke engine, the cylinder head becomes larger and an oil pan is required, so that the overall height of the engine becomes higher and it is difficult to mount the engine in an upright state.
Moreover, in the case of a 4-cycle engine, the alternator,
Since it is necessary to install new parts unique to the four-stroke engine, such as a supercharger, an intercooler, and an oil filter, layout in a limited space in the engine room is extremely difficult. Further, a starter of an engine in a snowmobile is generally a recoil starter, but it is difficult to start a four-cycle engine with a recoil starter, so a starter motor is required. Therefore, it is necessary to lay out the engine in consideration of the structure of the starter and the arrangement of the starter motor.

[0005] The present invention has been made in view of the above-mentioned conventional problems, and comprises a starter motor.
It is an object of the present invention to provide a four-stroke engine for snowmobiles that saves space.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a four-stroke engine in which a snowmobile engine has a cylinder head disposed on an upper side, and is provided at a front portion of a vehicle body of the snowmobile. In the engine room formed, turn the crankshaft almost parallel to the vehicle width direction,
The engine body is disposed to be inclined forward in the vehicle traveling direction, a flywheel is provided at one end of the crankshaft, a centrifugal clutch is provided outside the flywheel, and an auxiliary device driving device is provided at the other end of the crankshaft. A transmission means, an alternator is disposed on the upper part of the inclined engine body on the side of the auxiliary device driving transmission means, and a starter motor is disposed on the flywheel side of the upper part of the engine body. An intake path is arranged above the motor. Further, the structure of the engine includes a driving gear on an output shaft of the starter motor, and a driven gear on an outer periphery of the flywheel.
It is preferable that the starter motor is arranged at a position where the drive gear and the driven gear mesh with each other.

According to the present invention, even if a four-stroke engine has a high overall height by leaning the engine forward, the overall height can be reduced, so that it can be mounted on a snowmobile. Further, by providing a flywheel at one end of the crankshaft, the driving force of the engine can be effectively used. In addition, by providing the starter motor and the alternator at positions opposite to each other in the vehicle width direction on the upper side of the inclined engine, the space at the upper side of the engine can be effectively used, and the overall height of the engine can be reduced. Further, by directly driving the driven gear provided on the flywheel by using the drive gear provided on the output shaft of the starter motor, transmission loss can be reduced and space can be saved.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory view showing the entire configuration of a four-stroke engine for snowmobiles according to an embodiment of the present invention, FIG. 2 is a partial sectional view showing the configuration of the engine, and FIG. 3 is a rear view of the engine. FIG. 4 is a partially cutaway front view showing the position of the starter motor of the present embodiment. The structure of the four-stroke engine for a snowmobile according to the present embodiment is, as shown in FIG.
A four-stroke engine 2 (hereinafter referred to as an engine) having a crankshaft 7 disposed substantially in the width direction of the vehicle in an engine room 6 formed inside a front cover 4 on the front side of the vehicle body of the snowmobile 1. Parallel to the engine 2
The main body is arranged to be inclined forward in the direction of vehicle body movement.

The snowmobile 1 has a pair of left and right steering sleds 13 rotatably mounted on a lower portion of a front portion 11 of a frame 10 extending in the front-rear direction so as to face left and right. A driving crawler 16 for circulating the track belt 15 is provided. The crawler 16 is circulated around the drive wheels 17 disposed at the front end of the frame rear portion 12, the driven wheels 18 disposed at the rear end, the plurality of intermediate wheels 19, the suspension mechanism 20, and the respective wheels. A track belt 15 is provided.

A long tandem-type seat 22 is disposed above the frame rear portion 12. Steps 23, which are one step lower than the seat 22, are provided on both sides of the seat 22 in the vehicle width direction. A steering shaft 24 is erected substantially at the center of the vehicle body between the seat 22 and the front cover 4, and a bar handle 26 is provided at an upper end of the steering shaft 24 so as to extend slightly left and right in the horizontal direction. ing. The steering sled 13 is operated by the bar handle 26 via a steering shaft 24. A windshield 28 is erected in the front near the bar handle 26, and the front cover 4 has a substantially streamlined shape and a gently lowered shipboard bottom that is forwardly inverted from the base of the windshield 28. It has a shape.

The frame 10 is formed in a monocoque frame structure. A front portion 11 of the frame on which the engine 2 is mounted has a front portion protruding upward from a main portion 11a, and supports a steering sled 13. A front suspension housing 11b accommodating an upper portion of the front suspension 13a is formed, and a crawler 1 has a shape in which a rear portion from the main portion 11a rises obliquely rearward and upward.
A track housing 11c that accommodates the vicinity of the upper portion of the sixth drive wheel 17 is formed continuously and integrally with the frame rear portion 12. The frame rear portion 12 extends over the rear end portion in the vehicle front-rear direction and also serves as a cover that accommodates the entire crawler 16 below.

As shown in FIGS. 1 and 2, the engine 2 is a three-cylinder, four-stroke engine having a cylinder head 3 disposed at an upper position. The engine 2 has a crankshaft 7 oriented substantially parallel to the vehicle width direction. The cylinder head 3 is largely inclined in the vehicle traveling direction, and is disposed substantially at the center of the engine room 6 inside the front cover. An intake path 40 is provided above the main body of the engine 2, and an alternator 51 is provided behind the intake path 40, and an air cleaner 52 is provided further behind the intake path 40.

At one end 7a of the crankshaft 7, there is provided a flywheel 54 provided with a driven gear 54a on the outer periphery, and a V-belt type continuously variable transmission having a centrifugal clutch device 55 built in the outside of the flywheel 54. Machine 56 is connected. The continuously variable transmission 56 is configured to transmit drive to the track belt 15 via a gear or the like on a passive side. The other end of the passive shaft of the continuously variable transmission 56 is provided with a brake (not shown). The crankshaft 7
The other end 7b is provided with a pulley 63 as an auxiliary device driving transmission means, and drives the alternator 51 and the water pump 53 provided on the pulley 63 side.

A starter motor 60 is arranged below the intake path 40 such as a carburetor and a throttle body near the flywheel 54 on the upper side of the engine 2 body. The starter motor 60 is disposed on the opposite side of the alternator 51 as shown in FIGS. 3 and 4, a drive gear 61 a is provided on an output shaft 61, and a driven gear 54 a of the flywheel 54 is provided. It is arranged at a position where the driving gear 61a meshes.

Further, on the upper part of the engine 2 main body,
An intake manifold 65 is provided, which branches an intake passage from the carburetor 66 to an intake hole of each cylinder and communicates therewith. Vaporizer 66 from intake manifold 65
The intake system of the air cleaner 52 and the air cleaner 52 is arranged so as to extend rearward at a position higher than the upper position of the cylinder head 3. The intake system is located inside the raised portion near the base of the windshield 28 of the front cover 4. The upper end of the cylinder head 3 is housed without interfering with other parts inside the front side where the front cover 4 is gradually lowered.

The engine 2 is mounted as shown in FIG.
In a state where the engine 2 is tilted forward on the frame front part 11, the oil pan 30 is adjacent to the inclined track housing 11c, and the cylinder case 31 is adjacent to the suspension housing 11b. The engine 2 is mounted along.

The engine 2 is mounted on the truck housing 11c via an oil pan side bracket 35, and is mounted on the suspension housing 11b via a cylinder case side bracket 36. The oil pan side bracket 35 and the cylinder case side bracket 36 are both formed of angle fittings provided on the front and rear sides of the engine 2.
7 are supported by the frame front part 11 in a floating manner. As described above, by attaching the front and rear of the engine 2 to the frame front portion 11 via the brackets 35 and 36 and the shock absorbing material 37, the engine 2 is securely and stably mounted in the engine room 6. be able to.

According to the above configuration, the height of the engine 2 can be suppressed low by attaching the engine 2 to the truck housing 11c and the suspension housing 11b by tilting the bracket forward with appropriate dimensions. Further, the engine 2 is tilted forward, and a starter motor 60 and an alternator 51 are mounted on an upper portion of the tilted engine 2.
Are provided at opposite positions in the width direction of the vehicle body, so that the space above the engine 2 can be effectively used without interfering with each other. Therefore, even with a four-stroke engine having a high overall height, the installation height can be suppressed, and the engine can be mounted on a snowmobile. By providing the flywheel 54 at one end of the crankshaft 7, the driving force of the engine 2 can be effectively used. Also,
By providing a drive gear on the output shaft of the starter motor 60 and directly driving a driven gear provided on the flywheel 54, transmission loss can be reduced and space can be saved.

[0019]

As described above, according to the present invention, even when a four-stroke engine having a high overall height can be lowered by tilting the engine forward, the present invention can be mounted on a snowmobile. In addition, the starter motor is mounted at the opposite position in the vehicle width direction from the position of the alternator on the upper part of the inclined engine, thereby effectively utilizing the space on the upper part of the engine.
The overall height of the engine can be kept low. Further, by providing a flywheel at one end of the crankshaft, the driving force of the engine can be effectively used. Further, by directly driving the driven gear provided on the flywheel using the drive gear provided on the output shaft of the starter motor, transmission loss can be reduced and space saving can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a snowmobile four-stroke engine according to an embodiment of the present invention.

FIG. 2 is a partial sectional view showing a configuration of the engine.

FIG. 3 is a rear view of the engine.

FIG. 4 is a partially cutaway front view showing a position of a starter motor of the embodiment.

FIG. 5 is an explanatory diagram showing the overall configuration of a conventional snowmobile four-stroke engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Snowmobile 2 Engine 3 Cylinder head 4 Front cover 6 Engine room 7 Crankshaft 10 Frame 11 Frame front part 11a Main part 11b Front suspension housing 11c Truck housing 12 Frame rear part 30 Oil pan 35 Oil pan side bracket 36 Cylinder case side bracket 37 Shock absorber 51 Alternator 54 Flywheel 56 Continuously variable transmission 60 Starter motor

Claims (2)

[Claims] 1. A four-stroke engine having a cylinder head disposed on an upper side thereof, wherein a crankshaft is directed substantially parallel to a width direction of a vehicle body in an engine room formed at a front part of a vehicle body of a snowmobile. It is disposed inclined forward in the traveling direction, comprises a flywheel at one end of the crankshaft, comprises a centrifugal clutch outside the flywheel, and comprises an auxiliary device driving transmission means at the other end of the crankshaft, An alternator is arranged on the side of the auxiliary device driving transmission means on the upper side of the inclined engine main body, and a starter motor is arranged on the flywheel side of the upper side of the engine main body, and air is taken in above the starter motor. A structure of a four-stroke engine for snowmobiles, wherein a route is arranged. 2. The method according to claim 1, further comprising: a driving gear provided on an output shaft of the starter motor, a driven gear provided on an outer periphery of the flywheel, and the starter motor disposed at a position where the driving gear meshes with the driven gear. Characteristic 4-stroke engine structure for snowmobiles.