JPH0557404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine lubricating device for a motorcycle.

Generally, four-cycle engines are lubricated by providing an oil pan at the bottom of the engine and circulating lubricating oil stored in the oil pan into the engine. However, since the head of a 4-stroke engine is higher than that of a 2-stroke engine, it is difficult to secure that clearance for off-road motorcycles, which require a relatively large gap between the bottom of the engine and the road surface. There are problems with installing it as is. For this reason, there is a so-called dry sump type lubricating system in which an oil tank is not provided at the bottom of the engine and an oil tank is provided separately outside the engine in order to ensure a sufficient clearance between the lubricant and the road surface. However, in conventional dry sump type equipment, the oil tank is installed in a position that is sandwiched between the main frame and the down tube immediately after the head pipe, so a circulation pipe is inevitably needed to connect the oil tank and the engine. This results in a wasteful situation in which lubricating oil must be stored in the oil tank in an amount corresponding to the capacity occupied by the long circulation pipe. Furthermore, since the oil tank is installed at a position considerably distant from the center of gravity of the vehicle, there is also the disadvantage that the steering stability of the vehicle is reduced.

Therefore, in order to shorten the circulation pipe and lower the vehicle's center of gravity, it is conceivable to place the oil tank on the back of the engine crankcase. Due to such interference, it is extremely difficult to secure space for the oil tank. Also,
If the oil tank is forcibly placed in such a narrow space, the oil tank and engine will come into close contact with each other, resulting in poor cooling of the engine and oil tank.

In view of the problems of the dry sump type lubrication system as described above, an object of the present invention is to reduce the amount of lubricating oil to be stored in the oil tank as much as possible while ensuring the cooling performance of the engine and oil tank. Moreover, it is an object of the present invention to provide an engine lubricating device for a motorcycle that can improve the steering stability of the vehicle.

The engine lubricating device for a motorcycle according to the present invention achieves the above object, and a closed loop circulation path is formed between a four-cycle engine and an oil tank provided outside the engine via a circulation pipe, and a pump is connected to the circulation path. In an engine lubricating system that forcibly circulates lubricating oil using The oil tank is arranged in a space on the back side of the crankcase of the engine, with a gap between the cylinder and the crankcase, and the pump is arranged at the bottom of the crankcase. It is something.

Hereinafter, the present invention will be explained with reference to embodiments shown in the drawings.

In the figure, 1 is a head pipe, and a main frame 2 and a down tube 3 are connected to the rear part of the head pipe 1. A four-suncle engine 4 is mounted below the triangular area surrounded by the main frame 2 and down tube 3. The engine 4 has a cylinder 5 and a piston 6, and further includes a cylinder 5 and a piston 6.
A crank case 8 containing a crankshaft 7 and the like is provided below. The cylinder 5 is tilted forward with respect to the vehicle body, and the cylinder head 2 is attached to the upper part of the cylinder 5.
2, an intake passage 22a and an exhaust passage 22b are formed in the longitudinal direction of the vehicle body. The intake passage 22a provided on the rear side extends obliquely upward and rearward, and a carburetor 23 is connected to the intake passage 22a so as to be tilted forward.
On the other hand, an oil pan for storing lubricating oil is not provided in the lower part of the crankcase 8.

At the rear of the engine 4 and on the back of the crankcase 8, an oil tank 9 for storing lubricating oil is inserted into the lower side of the intake passage 22a.
It is installed in place of an oil pan. This oil tank 9 is supported so as to be disposed with a gap between the cylinder 5 and the crankcase 8. A rear wheel shock absorber 10 is arranged behind the oil tank 9, and the oil tank 9 is arranged to be sandwiched between the shock absorber 10 and the engine 4.
As shown in the enlarged perspective view of FIG. 2, the oil tank 9 has a bottom portion 9b shaped to protrude and extend rearward, and its cross-sectional area is larger than that of the upper portion, so as to secure as large a volume as possible in a narrow space. There is. In addition, an inclined recess 9a is formed on the upper back surface.
It is arranged so that it does not interfere with the shock absorber 10. A lubricating oil outlet 11 is provided at the bottom of the oil tank 9, and lubricating oil return ports 12, 1 are provided at the upper front and top surfaces, respectively.
3 is provided. 20 is a fuel filler port, 21
is the lid of the fuel filler port 20.

A circulation pipe 14 is connected to the outlet 11 at the bottom of the oil tank 9, and the other end of the circulation pipe 14 is connected to the suction side of a pump 17 provided at the bottom of the crankcase 8. Also, the circulation pipe 15 is also connected to the return port 12.
The other end of this circulation pipe 15 is connected to the discharge side of another pump 18. Further, a return port 13 on the upper surface of the oil tank 9 communicates with the inside of a head cover 19 of the engine 4 via a circulation pipe 16.

The lubricating oil in the oil tank 9 is sucked by the pump 17 through the circulation pipe 14, is forcibly fed to each part in the engine 4, lubricates each part, and then flows back to the bottom surface of the crankcase 8. The refluxed lubricating oil is then sucked into the pump 18 and refluxed to the oil tank 9 via the circulation pipe 15. Further, a small amount of mist-like lubricating oil scattered within the head cover 19 is returned to the oil tank 94 via the circulation pipe 16. Therefore, with the above configuration, a closed loop is formed between the engine 4 side and the oil tank 9 via the circulation pipes 14, 15, and 16.

In the engine lubricating device described above, the cylinder 5
By tilting the engine forward and directing the intake passage 22a diagonally upward and backward, the space on the back of the crankcase 8 is expanded as much as possible, and the oil tank 9 is placed as far forward as possible in this expanded space. As a result, the total length of the circulation pipes 14, 15, and 16 connecting with the engine can be shortened overall compared to the conventional system in which the oil tank is placed immediately after the head pipe 1. can. Therefore, the internal volume occupied by the circulation pipes 14, 15, 16 is smaller than that of the conventional device, and the amount of lubricating oil to be stored can be reduced accordingly. In addition, since the oil tank 9 is located close to the vehicle center of gravity G of the motorcycle, the center of gravity of the vehicle is lower than that of conventional dry sump type devices, and the mass is concentrated at the vehicle center of gravity G, which improves maneuverability. This has the effect of stabilizing the vehicle and making it possible to make the vehicle more compact. Furthermore, since the pumps 17 and 18 are located at the lower part of the crankcase 8, this contributes to shortening the circulation pipes 14 and 15, and this shortening can also reduce the load on the pumps themselves.

In this case, since the oil tank 9 is placed in the expanded space on the back of the crankcase 8 with a gap between the cylinder 5 and the crankcase 8, the heat dissipation area of the engine 4 and the oil tank 9 is large. At the same time, when the vehicle is running, air passes through the gaps between them, ensuring cooling performance. Furthermore, when the carburetor 23 is heated by the heat of the engine or the like, its function deteriorates due to a decrease in air density. The carburetor 23 is also easily cooled by the traveling wind passing above the carburetor 23, which has the advantage that its functionality is less likely to deteriorate.

As described above, the engine lubricating device for a motorcycle according to the present invention tilts the engine cylinder forward and extends the intake passage provided at the rear of the cylinder head diagonally upward and rearward. Expand the space as much as possible,
Because the oil tank is placed in this expanded space, the total length of the circulation pipe can be shortened compared to conventional equipment in which the oil tank is placed immediately after the head pipe, and the amount of lubricating oil stored can be reduced by the shortened length. . In addition, the above arrangement allows the vehicle to have a low center of gravity and the mass to be concentrated at the vehicle center of gravity, so that the steering stability of the vehicle can be further improved and the vehicle can be made more compact.

Moreover, in the above configuration, since the oil tank is disposed in the enlarged space on the back surface of the crankcase with a gap between the cylinder and the crankcase, cooling performance of the engine and the oil tank can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main parts of a motorcycle equipped with the device of the present invention, and FIG. 2 is a perspective view of an oil tank provided in the device. 4...Engine, 5...Cylinder, 8...Crankcase, 9...Oil tank, 11...(Lubricating oil) outlet, 12, 13...(Lubricating oil) return port, 1
4, 15, 16... Circulation pipe, 17, 18...
Pump, 22... cylinder head, 22a... intake passage, 22b... exhaust passage, 23... carburetor.

Claims (1)

[Claims] 1 Engine lubrication in which a closed loop circulation path is formed between the 4-stroke engine and an oil tank installed outside the engine via a circulation pipe, and lubricating oil is forced to circulate through this circulation path using a pump. In the device, the cylinder of the engine is tilted forward, and the intake passage provided at the rear of the cylinder head is extended obliquely upward and rearward, and the air intake passage is inserted into the space above the back of the crankcase of the engine below the intake passage. An engine lubricating device for a motorcycle, characterized in that an oil tank is disposed between the cylinder and the crankcase, and the pump is disposed below the crankcase.