JPH0899669A - Water-cooled engine for motorcycle - Google Patents

Abstract

PURPOSE: To improve the layout of an exhaust muffler and reduce the flow resistance of cooling water and weight by forming a cooling water passage, extended outside from a water pump so as to be connected to a radiator, linearly with the shortest distance without interfering with the exhaust muffler. CONSTITUTION: A water pump is disposed at a front part in a crankcase and at a center part in a vehicle width direction, and a cooling water passage 41 led outside from the water pump so as to be connected to a radiator 13L is extended to the body side face on the side where an exhaust muffler 11 is not disposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle water-cooled engine constructed so that a cooling water passage extending from a water pump provided in a crankcase to the outside is connected to a radiator.

[0002]

2. Description of the Related Art In a general motorcycle, an engine is mounted on the front half of a vehicle body frame, and when the engine is water-cooled, a radiator for heat exchange of the cooling water is installed on the forehead of the vehicle body frame. To be done. In this case, the engine crankcase is equipped with a water pump,
A suction passage led out from the water pump is connected to the radiator, and a discharge passage of the water pump is connected to a water jacket formed in the cylinder assembly.

By the way, particularly in a motorcycle for off-road running, an exhaust muffler extending forward from the cylinder assembly is disposed so as to wrap around the side surface of the vehicle body to sufficiently secure a minimum ground clearance below the engine. Usually, the exhaust muffler is arranged on the side surface of the vehicle body opposite to the chain in order to avoid interference with the chain that drives the rear wheels.

On the other hand, the water pump is often arranged on the same side as the clutch mechanism, that is, on the opposite side of the chain, for the sake of layout in the crankcase, and therefore the suction passage led out from the water pump. Had a layout that extended to the same side as the exhaust muffler.

[0005]

However, when the suction passage of the water pump is extended to the same side as the exhaust muffler, the rubber hose forming the suction passage comes into contact with the hot exhaust muffler and burns out. Because of fear
It is necessary to avoid the rubber hose and pass the exhaust muffler to the outside in the vehicle width direction, or to bend the rubber hose skillfully to avoid the exhaust muffler.

[0006] However, if a method of passing the exhaust muffler outside the vehicle width direction while avoiding the rubber hose is adopted, the layout property of the exhaust muffler is remarkably deteriorated and the vehicle body design becomes difficult, and the motorcycle due to the extension of the exhaust muffler. The vehicle width of the vehicle is widened, and the exhaust muffler easily interferes with the legs of the occupant, which is not preferable.

If the method of bending the rubber hose to avoid the exhaust muffler is adopted, the structure of the mold for manufacturing the rubber hose becomes complicated, leading to an increase in cost, and the passage resistance of the cooling water flowing in the rubber hose increases to increase the water resistance. The size of the pump must be increased, and the amount of cooling water increases with the extension of the rubber hose, resulting in an increase in weight.

The present invention has been made in order to solve such a problem, and the cooling water passage extending from the water pump to the outside and connected to the radiator is linearly arranged at the shortest distance without interfering with the exhaust muffler. An object of the present invention is to provide a water-cooled engine for a motorcycle, which is configured to improve layout characteristics of an exhaust muffler and to reduce passage resistance of cooling water and reduce weight.

[0009]

To achieve the above object, in a water-cooled engine for a motorcycle according to the present invention, a water pump for discharging cooling water is provided in a crankcase, and an exhaust gas extending forward from a cylinder assembly is provided. In a water-cooled motorcycle engine in which a muffler is arranged so as to wrap around the side of the vehicle body, the water pump is arranged in the front of the crankcase and at the center of the vehicle in the vehicle width direction, and is guided to the outside from the water pump. The cooling water passage connected to the above is extended to the side surface of the vehicle body on the side where the exhaust muffler is not arranged.

[0010]

According to the water-cooled engine for a motorcycle having the above structure, the cooling water passage is extended to the side surface of the vehicle body where the exhaust muffler is not arranged. There is no concern that the muffler will interfere. For this reason, it is not necessary to avoid the exhaust muffler by passing the exhaust muffler outside the vehicle width direction or by bending the rubber hose intricately as in the conventional case.

Further, since the water pump is arranged in front of the crankcase, the distance between the water pump and the radiator is narrowed, and the cooling water passage extending from the water pump to the outside and connected to the radiator is made short. Moreover, since the water pump is located at the central portion in the vehicle width direction, the bending rate of the cooling water passage can be increased. With these, the cooling water passage is linearly configured with the shortest distance.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a left side view showing a state in which a water-cooled engine 2 according to the present invention is mounted on the front half of a vehicle body frame 1 of a motorcycle, and FIG. 2 is a front view taken along the arrow II of FIG.

The body frame 1 is, for example, of a semi-double cradle type, and has a head pipe 1a for supporting a front fork (not shown) and the head pipe 1.
an upper tube 1b and a down tube 1c extending rearward and downward from a, a pair of left and right bottom tubes 1d connected to the down tube 1c, a center tube 1e connecting the rear ends of the upper tube 1b and the bottom tube 1d, and a reinforcement It has a pipe 1f.

On the other hand, the water-cooled engine 2 is, for example, a single-cylinder two-cycle engine, and a cylinder assembly 4 is provided upright on the upper surface of a crankcase 3 thereof, for example, mounting pedestals provided before and after the crankcase 3. 5,
6 are fixed to the mounting bracket 7 and the center tube 1e of the bottom tube 1d, and a mounting pedestal 8 provided on the top of the cylinder assembly 4 is fixed to a mounting bracket 9 extending from the upper tube 1b.

Exhaust muffler from the cylinder assembly 4
An exhaust muffler 11 extends forward, and the exhaust muffler 11 is arranged so as to wrap around the side surface of the vehicle body to secure a minimum ground clearance.
Since a chain for driving a rear wheel (not shown) is wound around a sprocket 12 provided on the left side surface of the water-cooled engine 2, the exhaust muffler 11 is located on the right side of the vehicle body frame 1 in order to avoid interference with the chain. It is arranged so as to wrap around.

A pair of left and right radiators 13L and 13R are fixed near the front of the body frame 1, for example, on both sides of the down tube 1c. These radiators 13
L and 13R are for exchanging the cooling water of the water-cooled engine 2 with heat.

FIG. 3 is a cross-sectional view of the crankcase 3 taken along the line III-III in FIG. In the crankcase 3,
A crank shaft 14 and a counter shaft 15 are rotatably supported so as to extend in the vehicle width direction from the front.
The drive gear 16 provided integrally with the counter shaft 15
It is meshed with a driven gear 17 mounted on the shaft.

A clutch mechanism 19 is axially mounted on the counter shaft 15, and a continuously meshed multi-stage transmission 20 is provided between the counter shaft 15 and a drive shaft (not shown) which is supported behind the counter shaft 15. The sprocket on the left end of the shaft
Since 12 is fixed integrally with the rotation, the rotation of the crankshaft 14 is transmitted through the countershaft 15 and the drive shaft, taken out as an output from the sprocket 12, and then transmitted to the rear wheel of the motorcycle through the chain. , The rear wheels are driven.

By the way, the crankcase 3 is constituted by, for example, a left half case 3L and a right half case 3R, which are divided into two parts along a mating surface C orthogonal to the axial direction of the crankshaft 14. A magnet cover 3a is attached to the left side of the case half 3L, and a clutch cover 3b is attached to the right side of the case half 3R as separate parts.

A water pump 21 is provided in the front of the crankcase 3 and in the center in the vehicle width direction. The water pump 21 is a pump for cooling the cylinder assembly 4 by circulating cooling water in a water jacket (not shown) formed in the cylinder assembly 4.

The pump chamber 22 of the water pump 21 is formed so as to straddle the mating surface C of the crankcase 3.
A left end of a rotary shaft 23 extending in the vehicle width direction projects into the pump chamber 22. The rotary shaft 23 is rotatably supported by a bearing 24 provided on the clutch cover 3b and bearings 25 and 26 provided on the case half 3R of the crankcase 3, and is attached to the left end of the rotary shaft 23. The impeller 27 provided integrally with the rotation is adapted to rotate in the pump chamber 22.

On the other hand, a governor device 29 is provided on the right half of the rotary shaft 23.
Is provided. The governor device 29 is for operating the exhaust timing control device 30 provided in the cylinder assembly 4, for example. An intermediate shaft 31 is rotatably supported by bearings 32 and 33 between the crankshaft 6 and the rotary shaft 23, and a first intermediate gear 34 and a second intermediate gear 35 rotate on the intermediate shaft 31. It is provided integrally. Then, the drive gear 16 of the crankshaft 6 is replaced by the first intermediate gear 34.
The second intermediate gear 35 meshes with the governor driven gear 36 of the governor device 29.

Further, the crankcase 3 is formed with a suction passage 38 and a discharge passage 39 which are connected to the pump chamber 22 of the water pump 21. Here, the suction passage 38 is formed in the case half 3L so as to extend toward the side surface of the vehicle body where the exhaust muffler 11 is not disposed, that is, the left side of the vehicle body, and the discharge passage 39 extends from the peripheral portion of the pump chamber 22. The case half body 3L and the case half body 3R are formed so as to extend upward in the tangential direction and communicate with the water jacket.

A union 40 is press-fitted into the inner diameter of the suction passage 38 from the outside left side, and the union 40 is connected with a cooling water passage 41 made of a rubber hose shown in FIGS.
Therefore, the cooling water passage 41 is led out to the side surface of the vehicle body (here, the left side) opposite to the exhaust muffler 11. The other end of the cooling water passage 41 is connected to a union 42 provided below the left radiator 13L.

The left and right radiators 13L and 13R are connected at their upper and lower parts by connecting hoses 44 and 45, respectively.
A cooling water passage 46 made of a rubber hose branching from the upper connection hose 44 is connected to a union 47 provided at the top of the cylinder assembly 4. The union 47 communicates with a water jacket in the cylinder assembly 4.
Reference numeral 48 is a radiator cap for replenishing the radiator 13L, 13R with cooling water.

When the water-cooled engine 1 is operated, the rotation of the crankshaft 14 is transmitted to the rotary shaft 23 via the intermediate shaft 31, and the impeller 27 rotates in the pump chamber 22 of the water pump 21. As a result, the cooling water that has undergone heat exchange with the radiators 13L and 13R is sucked into the pump chamber 22 through the cooling water passage 41 and the suction passage 38, and is discharged from the discharge passage 39. The discharged cooling water flows into the water jacket in the cylinder assembly 4 to cool the cylinder assembly 4, and then is returned to the radiators 13L and 13R via the cooling water passage 46 to be heat-exchanged.

The water-cooled engine 2 constructed as described above
Since the cooling water passage 41 led out from the water pump 21 is extended to the left side surface of the vehicle body where the exhaust muffler 11 is not disposed, the rubber hose and the exhaust muffler 11 that constitute the cooling water passage 41 are There is no need to avoid the rubber hose and to project the exhaust muffler 11 outward in the vehicle width direction as in the prior art, or to bend the rubber hose intricately to avoid the exhaust muffler 11 as in the conventional case.

Therefore, the layout of the exhaust muffler 11 is greatly improved, the problem of the vehicle width increase of the motorcycle due to the extension of the exhaust muffler 11 can be solved, and the structure of the mold for manufacturing the rubber hose can be prevented from becoming complicated. be able to.

Further, since the water pump 21 is arranged in front of the crankcase 3, the water pump 21
The distance between the radiator 21 and the radiator 13L is narrowed, and the cooling water passage 41 connecting the two is shortened. Moreover, water pump
Since 21 is located in the central portion in the vehicle width direction, the bending rate of the cooling water passage 41 can be increased. As a result, the cooling water passage 41 is linearly configured with the shortest distance, and the passage resistance of the cooling water can be reduced and the weight can be reduced.

Since the water pump 21 is located in the center of the crankcase 3 in the vehicle width direction and does not project to the side surface of the crankcase as in the conventional case, the water pump 21 will not be projected on the road surface when the motorcycle falls over. It is prevented from colliding with and being damaged. Further, since the water pump 21 is separated from the exhaust muffler 11, the layout of the exhaust muffler 11 is further improved.

[0031]

As described above, in the water-cooled engine for a motorcycle according to the present invention, the water pump for discharging the cooling water is provided in the crankcase, while the exhaust muffler extending forward from the cylinder assembly is provided on the side surface of the vehicle body. In a water-cooled engine of a motorcycle arranged so as to wrap around, the water pump is arranged in front of the crankcase and in the center of the vehicle width direction, and a cooling water passage is led out from the water pump and connected to a radiator. Is extended to the side surface of the vehicle body on the side where the exhaust muffler is not disposed.

In this way, when the cooling water passage led out from the water pump is extended to the side surface of the vehicle body on the side where the exhaust muffler is not disposed, the rubber hose and the exhaust muffler forming this cooling water passage are separated from each other. Since there is no need to worry about interference, it is no longer necessary to avoid the rubber hose and pass the exhaust muffler to the outside in the width direction of the vehicle, or to bend the rubber hose intricately to avoid the exhaust muffler, which greatly improves the layout of the exhaust muffler. It is possible to avoid the increase of the vehicle width of the motorcycle and the complication of the rubber hose manufacturing type due to the overhang of the exhaust muffler.

Further, by disposing the water pump in front of the crankcase, the distance between the water pump and the radiator is narrowed, and the cooling water passage connecting the water pump and the radiator can be made short. Moreover, since the water pump is located at the central portion in the vehicle width direction, the bending rate of the cooling water passage can be increased. As a result, the cooling water passage is linearly configured with the shortest distance, and the flow resistance of the cooling water can be reduced and the weight can be reduced.

[Brief description of drawings]

FIG. 1 is a left side view showing a state in which a water-cooled engine according to the present invention is mounted on a front half of a vehicle body frame of a motorcycle.

FIG. 2 is a front view taken along the line II of FIG. 1, showing an embodiment of the present invention.

FIG. 3 is a cross-sectional view of the crankcase taken along the line III-III in FIG.

[Explanation of symbols]

 1 Body Frame 2 Water Cooled Engine 3 Crankcase 4 Cylinder Assembly 11 Exhaust Muffler 13L, 13R Radiator 21 Water Pump 38 Suction Passage 39 Discharge Passage 41 Cooling Water Passage

Claims (1)

[Claims] 1. A water-cooled engine for a motorcycle, wherein a water pump for discharging cooling water is provided in a crankcase, and an exhaust muffler extending forward from a cylinder assembly is arranged so as to wrap around a side surface of a vehicle body. Is located in the front of the crankcase and in the center of the vehicle width direction, and the cooling water passage that is led out from this water pump and is connected to the radiator extends to the side of the vehicle body where the exhaust muffler is not installed. A water-cooled engine for motorcycles that has been characterized.