JPS5815625Y2 - Overhead valve forced air-cooled general-purpose engine with fuel tank - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an overhead valve type forced air-cooled engine with a fuel tank, which is mainly used as a general-purpose engine.

Normally, a side valve type engine, which is often used in general-purpose engines, has a fuel tank above it because the overall height of the engine body is relatively low.

However, when an overhead valve type engine is used as a general-purpose engine, the above fuel tank arrangement increases the overall height of the engine by the height of the valve arm cover, making the engine larger and causing the center of gravity to be higher. The disadvantages arise.

Therefore, this type of engine has a drawback that it is difficult to use it as a general-purpose engine.

This invention eliminates the above-mentioned drawbacks, and also makes it possible to forcibly cool the fuel tank and the rocker cover located directly below it, thereby improving the cooling effect between the fuel in the tank and the rocker cover and its surrounding parts. The purpose is to be able to improve.

To this end, a recess is formed in the bottom wall of the fuel tank placed on the top of the engine, roughly along the outer contour of the rocker cover, into which the cover is inserted, and the recess is open to the rear, and there is a gap between this recess and the rocker cover. Another feature is that a portion of the engine cooling air is blown into the engine.

An embodiment of this invention will be described below based on screens.

FIG. 1 is a rear view of an overhead valve type forced air cooling engine, and FIG. 2 is a side view of the same engine.

In the figure, an engine E includes a piston 4, a crankshaft 5, and an outer shell structure including a crankcase 1, a head block 2, and a rocker cover 3, which integrally form a cylinder barrel.
, a camshaft 6 and a valve operating device VJP driven by the camshaft 6. Interlocking members such as intake and exhaust valves 7A and 7B are accommodated therein.

As shown in FIG. 2, a cooling device C is installed at the front of the engine E, which includes a flywheel fan type cooling fan 8 driven by the crankshaft 5, and a fan case 9 that covers the outer surface of the cooling fan 8. A fuel tank T is disposed above the fuel tank T, and is supported by a tank bracket 10 fixed to the head block 2.

A recess 12 is formed in the bottom wall 11 of the fuel tank T, extending from the center to the rear side, and recessed toward the inner surface of the tank.

This recess 12 is formed in a shape that roughly follows the outer contour of the rocker cover 3, and by inserting the rocker cover 3 into the inner space of the recess 12 at a small distance from the recess wall, the fuel tank T is formed.
is mounted at a lower position.

A gap between the recess 12 and the rocker cover 3 is used as a cooling air passage 13 through which cooling air passes.

Reference numeral 14 denotes a cooling air outlet provided at the rear end of the earthen wall of the fan case 9, from which cooling air is sucked out toward the cooling air passage 13 described above.

In the figure, reference numeral 15 is a tank cap, 16 is a carburetor, 11 is a recoil starter, and 18 is a cowling.

In addition, in the above embodiment, the outer surface of the rocker cover 3,
Alternatively, fins may be formed in the recess 12 to enhance the cooling effect.

Further, depending on the arrangement position of the rocker cover 3, the cooling air outlet 14 may be provided on a cooling air passage wall (for example, the cowling 1B) around the rocker cover 3.

As explained above, in this invention, a recess is formed in the bottom wall of the fuel tank, and the fuel tank is mounted and fixed on the engine while being fitted onto the recessed rocker cover. The overall height of the engine can be lowered by the height of the outer fitting, making the engine more compact and lowering its center of gravity.

Therefore, an overhead valve type engine with a fuel tank, which has high fuel efficiency and output, can be downsized to the same level as a valve side type engine, and its versatility can be improved.

Also, by using the gap between the above-mentioned recess and the rocker cover, engine cooling air is sent here to forcibly cool the rocker cover and the fuel in the fuel tank. In addition to enhancing the cooling effect with surrounding components, it is possible to reduce fuel evaporation loss and prevent vapor lock in the fuel supply path led out from the fuel tank.

Moreover, in this invention, since the recess formed in the bottom wall of the fuel tank is formed in a rear-opening shape, the front bottom of the fuel tank is communicated with, and fuel remains in the tank. In addition, the area of the bottom wall of the fuel tank that comes in contact with the cooling air that has flowed into the recess can be increased, and the cooling air that has flowed into the recess flows smoothly toward the rear of the fuel tank, so that the cooling effect can be improved. It can be increased further.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention; FIG. 1 is a rear view of the engine in longitudinal section, and FIG. 2 is a side view of the engine in longitudinal section. E...engine, T...-i fuel tank 1
3...Rocker cover, 8...Cooling fan/, 11...Bottom wall of T, 12...Recess, C...Cooling Device, 13... Cooling air passage, 14... Cooling air outlet.

Claims (1)

[Scope of utility model registration request] The front side of the overhead valve engine E is covered with a fan case 9, a cooling fan 8v is arranged inside the fan case 9, a fuel tank T is mounted and fixed on the top of the engine E, and the bottom wall 11 of the fuel tank T is attached to the bottom surface of the tank. A recess is formed across the tank and the rear side surface of the tank to form a recess 12 with an open rear side.
Inside □ Position the rocker cover 3 of the engine E, and press the recess 12.
This is an overhead valve type forced air-cooled general-purpose engine with a fuel tank, which is characterized by a structure in which a part of the engine cooling air can be supplied from a fan case 9 to the gap between the engine and the rocker cover 3.