JP2002087372A - Four-cycle engine structure of snowmobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a four-cycle engine structure for a snowmobile, achieving the space-saving mounting of a four-cycle engine by improving cooling effect on an air or an engine oil supplied to the engine without impairing maneuverability. SOLUTION: The four-cycle engine for the snowmobile comprises a cylinder head 3 provided in an engine room 6 formed at the front of a body of the snowmobile 1, at the upper side of the engine, a crank shaft directed almost parallel to the cross direction of the body, a body of the engine 2 arranged in frontward inclination to the moving direction of the body, and a suction passage 5 arranged at the upper side of the body of the frontward inclined engine 2. An intercooler 8 for cooling a suction air is arranged in a tunnel formed inside a body frame 10 on which a truck belt 15 is provided.

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.

[0003] As a worldwide trend in recent years, there has been a demand for a clean, quiet and environmentally friendly engine. 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.

[0004] Conventional snowmobiles 200 generally include:
As shown in FIG. 5, the vehicle body frame 210 has a monocoque frame structure, and a truck housing 2 formed on a frame front portion (engine mount frame) 211.
The engine 202 is mounted in the space between the front suspension housing 11c and the front suspension housing 211b.
6, the engine 202 is mounted upright.

When a four-stroke engine is to be mounted on a snowmobile in the same manner as described above, the cylinder head becomes larger than the two-stroke engine, and an oil pan is required. In other words, it was difficult to mount it upright. And 4
In the case of a cycle engine, it is very difficult to lay out in a limited space in the engine room because it is necessary to newly install parts specific to the 4-cycle engine, such as an alternator, a supercharger, an intercooler, and an oil filter. Have been.

Therefore, by tilting the engine forward, the overall height of the engine is reduced so that the engine can be mounted in an engine room, and the above-described components and the like are arranged in a space formed by tilting the engine. Things have been suggested.

On the other hand, as a measure for increasing the output of a four-cycle engine which is lower than that of a two-cycle engine, generally, a supercharger (a so-called turbocharger) is provided on the intake side of the engine to supply air supplied to a combustion chamber. There is known a method of increasing the engine output by increasing the amount of fuel or fuel.

[0008]

However, when a supercharger is provided in an engine, it is effective to provide an intercooler in the intake path in order to improve the intake efficiency. It is necessary to install the engine at a position considering the cooling efficiency of the engine, and furthermore, there is a problem that it is affected by the mounting position of the supercharger, and it is very difficult to secure the layout and installation space in the engine room. .

[0009] For example, when the intercooler is arranged above the engine, the overall height of the engine is increased.
There is a problem that the center of gravity becomes high and the body of the snowmobile becomes high, which is not structurally preferable. In addition, when the intercooler is disposed in front of the engine, there is a problem that a heavy object is far from the position of the center of gravity, so that maneuverability is reduced. Furthermore, there is a problem that when a collision occurs in the front of the engine room, the damage is increased and the engine damage is increased.

Further, when a four-cycle engine is mounted on a snowmobile, if a V-belt type automatic transmission is used as a transmission, the engine is usually used at a higher speed than a four-wheeled vehicle. There is a problem that an increase in the calorific value of the engine and an increase in the temperature of the engine oil may cause the oil film to break and damage the engine.

The present invention has been made in view of the above-mentioned conventional problems, and has been made to improve the cooling effect of air and engine oil supplied to an engine and to save space without impairing maneuverability. It is an object of the present invention to provide a structure of a four-stroke engine for a snowmobile which can realize mounting of the four-stroke engine.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a structure of a four-stroke engine for a snowmobile, wherein a cylinder head is provided on an upper side of the engine in an engine room formed in a front portion of a vehicle body of the snowmobile, and a crankshaft is provided. A four-stroke engine for a snowmobile, wherein the engine body is oriented substantially parallel to the width direction of the vehicle body, the engine body is arranged to be inclined forward in the vehicle body traveling direction, and an intake path is arranged on an upper portion of the inclined engine body, A heat exchanger for cooling engine cooling water, engine oil, air supplied to the engine, or the like is disposed in a tunnel formed inside a vehicle body frame on which a traveling truck is provided. Things.

Further, it is preferable that the heat exchanger is disposed forward of a truck in the tunnel in the vehicle body traveling direction. Further, it is preferable that the heat exchanger is an intercooler for cooling air supplied to the engine. Preferably, the heat exchanger is an oil cooler for cooling engine oil. Further, it is preferable that the heat exchanger is a radiator for cooling engine cooling water. Further, it is preferable that the heat exchanger integrally forms an oil cooler for cooling engine oil and a radiator for cooling engine cooling water. Preferably, a thermostat is provided in the oil path of the oil cooler.

According to the present invention, a traveling truck is provided with a heat exchanger for cooling engine cooling water, engine oil, air supplied to the engine, etc. of a four-stroke engine for snowmobiles. By placing it in a tunnel formed inside the body frame, it is not affected by the heat in the engine room, and the cooling effect can be significantly improved by the snow powder rolled up during running. An engine structure can be provided. In addition, by arranging the heat exchanger outside the engine room, a 4-cycle engine can be mounted without increasing the overall height of the engine.
In addition to saving space in the engine room, the vehicle body can be configured to be low, so that there is an excellent effect that the maneuverability is not impaired.

[0015] Further, by disposing the heat exchanger forward of the truck in the tunnel in the vehicle body direction, the heat exchanger can be disposed substantially below the engine and close to the engine. Can be shortened, the communication path can be simplified, and the cost can be reduced.

Further, by applying an intercooler for cooling the air sent to the engine as the heat exchanger, it is possible to effectively cool the high-temperature air compressed by the supercharger. As a result, the output of the engine can be improved.

Further, by applying an oil cooler for cooling the engine oil as the heat exchanger, it is possible to effectively cool the engine oil in a high temperature state. Damage can be prevented and the operating state of the engine can be kept good.

Further, by applying a radiator for cooling the engine cooling water as the heat exchanger, the cooling water in a high temperature state can be effectively cooled, so that overheating of the engine can be prevented and the operating state of the engine can be prevented. Can be improved.

[0019] Further, by providing, as the heat exchanger, an oil cooler for cooling engine oil and a radiator for cooling engine cooling water integrally, the oil cooler and the radiator are separately provided. There is no need to provide them, space can be saved, and the number of parts can be reduced.

Further, by providing a thermostat in the oil path of the oil cooler, the engine oil can be maintained at an appropriate temperature, thereby preventing the engine oil from being overcooled and improving the operating condition of the engine. Can be

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a partial cross-sectional side view showing the entire configuration of a snowmobile four-stroke engine of Example 1 according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional plan view showing the whole configuration of the snowmobile four-cycle engine. is there.

As a first embodiment, the structure of a four-stroke engine for a snowmobile according to the embodiment is a four-stroke engine 2 (hereinafter, referred to as an engine) in which a cylinder head 3 is arranged on an upper side as shown in FIGS. ) Is installed in the engine room 6 formed inside the front cover 4 on the vehicle body front side of the snowmobile 1 (not shown).
Is oriented substantially parallel to the vehicle body width direction, the main body of the engine 2 is disposed to be inclined forward in the vehicle traveling direction, and the intake passage 5 is disposed at an upper portion of the inclined main body of the engine 2. A supercharger (turbocharger) 7 is provided in the engine room 6 in front of the main body of the engine 2 and is provided separately from the main body of the engine 2. An intercooler 8 for cooling is disposed in a vehicle body traveling direction forward in a tunnel formed inside a vehicle body frame 10 on which a track belt 15 for traveling described later is provided.

Here, the structure of the snowmobile 1 will be described in detail. As shown in FIGS. 1 and 2, the snowmobile 1 is rotatably installed below a frame front portion 11 of a body frame 10 extending in the front-rear direction such that a pair of left and right steering sleds 13 is directed in the left-right direction. , Frame rear 12
A driving crawler 16 for circulating the track belt 15 is arranged below the lower part. 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.

The body frame 10 has a monocoque frame structure, and a front portion (engine mount frame) 11 on which the engine 2 is mounted has a front portion protruding upward from a main portion 11a, and is used for steering. Sled 1
A front suspension housing 11b for accommodating an upper portion of the supporting front suspension 13a is formed, and a rear portion of the front portion of the main portion 11a rises obliquely rearward and upward. The housing 11c is formed continuously and integrally with the frame rear portion 12.

The frame rear portion 12 extends from the front to the rear of the vehicle body in a tunnel shape with the inside recessed upward, and also serves as a cover for housing the entire track belt 15 below. A saddle-shaped seat 22 is disposed above the rear portion 12 of the frame. 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. In front of the bar handle 26, a windshield 28 is erected, and the front cover 4 gently descends forward from the base of the windshield 28 in a substantially streamlined shape. Is presented. The steering sled 13 is operated by the bar handle 26 via a steering shaft 24.

Next, the configuration of the engine 2 will be described in detail. As shown in FIGS. 1 and 2, the engine 2 is a three-cylinder four-stroke engine in which a cylinder head 3 is disposed above, and a crankshaft (not shown) is oriented substantially parallel to the vehicle width direction, and The cylinder head 3 is tilted largely (for example, 45 ° or more forward) in the vehicle traveling direction, and is disposed substantially at the center of the engine room 6 inside the front cover 4. An intake path 5 such as a carburetor or a throttle body is provided above the engine 2 main body, and an alternator 31 is disposed behind the intake path 5.

A V-belt type continuously variable transmission 33 having a flywheel (not shown) at one end of the crankshaft (left side in the vehicle traveling direction) and having a centrifugal clutch device outside the flywheel is provided. Are linked.
The continuously variable transmission 33 is configured to transmit drive to the track belt 15 via a passive gear or the like. The other end of the passive shaft of the continuously variable transmission 33 is provided with a brake (not shown). At the other end of the crankshaft (on the right side in the direction of travel of the vehicle body), a pulley 34 as an auxiliary device driving transmission means is provided, and the alternator 31 and the water pump 35 provided on the pulley 34 side are driven. Have been.

A starter motor (not shown) is arranged below the intake path 5 such as a carburetor or a throttle body near the flywheel on the upper side of the engine 2 body.

Here, the intake system will be described. The structure of the intake system is such that the components arranged on the upper side of the engine 2 are arranged inside the raised portion near the windshield 28 base of the front cover 4, and the components arranged on the front side of the cylinder head 3 are arranged on the front cover 4. It is housed without interfering with other parts inside the front side where it gradually lowers.

An intake manifold 37 is provided on the upper side of the engine 2 so as to branch the intake passage 5 from the carburetor 36 into intake holes of the respective cylinders and communicate therewith. A supercharger 7 is disposed in front of the engine 2, and an air cleaner 32 is disposed at a front end in the engine room 6 in front of the supercharger 7. An intercooler 8 is disposed near the engine 2 outside the engine room 6 behind the engine 2 and inside the vehicle body frame 10.

One end of the supercharger 7 is connected to an intake passage 7a extending forward, and is connected to the air cleaner 32 via the intake passage 7a. The other end of the supercharger 7 is bent from the front side of the engine 2 along the side surface of the engine 2 into an L-shape in plan view, and extends rearward and downward in the vicinity of the engine crankshaft in side view. The provided intake passage 7b is connected, and is connected to the intercooler 8 via the intake passage 7b. The outlet side of the intercooler 8 is connected to an intake passage 8a. The intake passage 8a rises almost directly above the lower side of the engine 2 and is connected to the carburetor 36 disposed above the engine 2.

In order to supply air to the engine 2, air is introduced into the supercharger 7 from the front of the vehicle body via the air cleaner 32 and is compressed and sent. In the supercharger 7, the hot air is intercooled. The gas is cooled by 8 and sent to the carburetor 36, and is sent to each cylinder in the engine 2 via the intake manifold 37.

On the other hand, the exhaust path extends toward the front of the engine 2 from the cylinder case 39, and an exhaust manifold 41 is extended and connected to the inlet side of the supercharger 7. The outlet side of the supercharger 7 is located in front of the engine 2 main body.
An exhaust passage 42 extending rearward along the main body is arranged, and communicates with the muffler 43 installed on the rear side of the engine via the exhaust passage 42.

Next, mounting of the engine 2 will be described. As shown in FIG. 1, in the engine room 6, in a state where the engine 2 is tilted forward on the frame front portion 11 in the engine room 6, the oil pan 38 is brought close to the inclined truck housing 11 c, and The engine 2 is mounted along the frame front portion 11 with the cylinder case 39 approaching the suspension housing 11b.

The engine 2 is mounted on the truck housing 11c via an oil pan side bracket 45 and mounted on the suspension housing 11b via a cylinder case side bracket 46. The oil pan side bracket 45 and the cylinder case side bracket 46 are both formed of angle fittings provided on the left and right sides of the front and rear of the engine 2, and a shock absorbing material 47 such as a cushion rubber is provided at a portion to be fastened to the frame front portion 11. , And is floating supported by the frame front part 11.

As described above, according to the configuration of the first embodiment, the intake path 5 is disposed above the engine 2, and the supercharger 7 and the air cleaner 3 are disposed in front of the engine in the engine room 6.
2 and the intercooler 8 is arranged outside the engine room 6 and inside the vehicle body frame 10, so that the engine layout can be made compact and the engine 2 is not affected by heat and can be used for further driving. By the snow powder, the cooling effect of the intercooler 8 can be significantly improved, and the filling efficiency of the intake air can be increased. Also, the layout of the intake path and exhaust path
By extending the engine 2 from the front side to the rear side along the side surface of the engine 2 main body, the effect of cooling the intake path and the exhaust path by the traveling wind can be improved.

Next, a second embodiment will be described in detail with reference to the drawings. FIG. 4 shows a snowmobile 4 according to the second embodiment.
FIG. 5 is a partial cross-sectional side view showing the entire configuration of the cycle engine, and FIG. 5 is a partial cross-sectional view showing the entire configuration of the snowmobile four-cycle engine. Note that the same components as those in the first embodiment have the same reference numerals and description thereof will be omitted.

The structure of the four-stroke engine for a snowmobile according to the second embodiment is, as shown in FIGS. 3 and 4, a four-stroke engine 102 having a cylinder head 3 disposed on the upper side.
(Hereinafter referred to as an engine).
0, the crankshaft (not shown) is directed substantially parallel to the width direction of the vehicle body in the engine room 6 formed inside the front cover 4 on the front side of the vehicle body, and the main body of the engine 102 is tilted forward in the vehicle traveling direction. The intake path 5 is arranged on the upper part of the inclined main body of the engine 2.

Below the engine 102, an oil cooler 108 is disposed in a tunnel formed inside the vehicle body frame 10 in a forward direction of the vehicle body in a tunnel. A thermostat valve (not shown) is provided between the inside and outside of the oil path of the oil cooler 108.

The structure of the intake system is such that an intake path 5 such as a carburetor or a throttle body is provided above the main body of the engine 102, an alternator 31 is provided at the rear, and an air cleaner 132 is further provided at the rear.

As described above, according to the configuration of the second embodiment, the intake path 5 and the air cleaner 132
And the oil cooler 108 is arranged outside the engine room 6 and inside the front of the vehicle body frame 10, so that the engine layout can be made compact and the oil cooler 108 can be disposed inside a tunnel formed inside the vehicle body frame 10. Since it is arranged forward in the vehicle body traveling direction, it is possible to effectively cool the high-temperature engine oil by snow powder during traveling without being affected by heat from the engine 102, thereby preventing oil film shortage. The engine can be prevented from being damaged, and the operating state of the engine can be kept good. Further, by providing a thermostat in the oil path of the oil cooler 108, it is possible to prevent engine oil from being excessively cooled and to improve the operating state of the engine.

In the above embodiment, the intercooler 8 and the oil cooler 108 are used as heat exchangers.
And these are arranged in the tunnel-shaped concave portion inside the body frame 10. However, the present invention is not limited to this.
In this case, the engine cooling water can be effectively cooled, so that overheating of the engine can be prevented, and the operating state of the engine can be improved.

In the present invention, an oil cooler for cooling engine oil and a radiator for cooling engine cooling water may be integrally formed as a heat exchanger. It is not necessary to provide the oil cooler and the radiator separately, so that space can be saved and the number of parts can be reduced.

[0044]

As described above, the first aspect of the present invention is as described above.
According to the structure of the four-stroke engine for snowmobile described in any one of the first to seventh aspects, the heat exchanger for cooling the engine cooling water, the engine oil, or the air supplied to the engine of the snowmobile is provided in the engine room. By arranging it in a tunnel formed inside the body frame without arranging it, it saves space in the engine room,
Since the overall height of the engine can be kept low, an eco-friendly 4-cycle engine can be mounted. Further, according to the present invention, it is possible to provide a four-stroke cycle engine for a snowmobile in which the heat exchanger is not affected by the heat of the engine and the cooling effect is remarkably improved by snow powder that is rolled up during running. .

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view showing an entire configuration of a snowmobile four-stroke engine of Example 1 according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional plan view showing the entire configuration of the snowmobile four-stroke engine of the first embodiment.

FIG. 3 is a partial cross-sectional side view showing an overall configuration of a snowmobile four-stroke engine according to a second embodiment.

FIG. 4 is a partial cross-sectional plan view showing an overall configuration of a snowmobile four-stroke engine according to a second 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, 100 Snowmobile 2, 102 Engine 5 Intake path 6 Engine room 7 Supercharger 8 Intercooler 10 Body frame 16 Crawler 108 Oil cooler

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 35/16 F02M 35/16 Z

Claims (7)

[Claims] 1. An engine room formed in a front part of a vehicle body of a snowmobile, a cylinder head is provided on an upper side of an engine, a crank shaft is directed substantially parallel to a vehicle body width direction, and the engine body is moved in a vehicle body traveling direction. A four-stroke engine for snowmobiles, which is arranged to be inclined forward and an intake path is arranged above the inclined engine body, and cools engine cooling water, engine oil, air supplied to the engine, and the like. A four-stroke engine for a snowmobile, characterized in that a heat exchanger is disposed in a tunnel formed inside a body frame provided with a traveling truck. 2. The four-stroke engine for a snowmobile according to claim 1, wherein the heat exchanger is disposed forward of a truck in the tunnel in the vehicle body traveling direction. 3. The four-stroke engine for a snowmobile according to claim 1, wherein the heat exchanger is an intercooler for cooling air sent to the engine. 4. The four-stroke engine for a snowmobile according to claim 1, wherein the heat exchanger is an oil cooler for cooling engine oil. 5. The radiator according to claim 1, wherein the heat exchanger is a radiator for cooling engine cooling water.
Or the structure of a four-stroke engine for a snowmobile according to 2. 6. The heat exchanger according to claim 1, wherein the heat exchanger integrally forms an oil cooler for cooling engine oil and a radiator for cooling engine cooling water. 4. The structure of the four-stroke engine for a snowmobile according to item 1. 7. The structure of a four-stroke engine for a snowmobile according to claim 4, wherein a thermostat is provided in an oil path of the oil cooler.