JPS6133222Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a forced air cooling system for a vertical shaft engine, and aims to improve cooling performance by blowing a large amount of cooling air generated by a cooling fan onto the engine without wasting it.

In general, air-cooled vertical shaft engines have a fuel tank located above the fan case located at the top of the engine body, which not only increases the overall height of the engine, but also prevents the fuel tank from being exposed to direct sunlight or heat from the engine. The disadvantage was that the temperature of the fuel in the tank rose, causing vapor lock in the fuel supply path.

Therefore, in order to eliminate the above-mentioned drawbacks, the applicant previously proposed what is shown in FIG.

By arranging a centrifugal fan 22 and a fuel tank 23 side by side inside a fan case 21 that covers the upper space of the vertical shaft engine 20, the entire engine is made smaller and the cooling air generated by the centrifugal fan 22 is transferred to the fuel tank 23. The bottom surface 24 is guided to a head cowling 27 that covers the cylinder block 25 and cylinder head 26, so that the fuel tank 23 can also be cooled strongly.

However, in such a case, there is a problem that a gap S is created between the bottom wall 24 of the fuel tank 23 and the upper edge of the head cowling 27, and the cooling air leaks outside from this gap S, resulting in a decrease in the cooling air volume. It was hot.

In order to solve this problem, the present invention provides a centrifugal fan and a fuel tank side by side in the fan case, thereby reducing the size of the engine, and creating a space between the bottom of the fuel tank and the upper edge of the head cowling. A cooling air leakage prevention plate is provided on the tank stay to cover the gap that occurs in the tank stay, and the cooling air leakage prevention plate prevents the cooling air from leaking outside through the gap, thereby improving cooling performance.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall perspective view of a forced air-cooled vertical shaft engine, and FIG. 2 shows a cross-sectional plan view thereof. The upper space of this engine 1 is covered with a fan case 2, and inside the fan case 2, a centrifugal flywheel fan 3 and a fuel tank 4 are arranged side by side.

The flywheel fan 3 is fixed to the upper end of a crankshaft 6 that is rotatably supported above and below the crankcase 5.

The side 4a of the fuel tank 4 facing the flywheel fan 3 is concavely curved to form an air guide surface 7, and the bottom surface 4b of the upstream half in the direction of rotation of the flywheel fan 3 is formed so as to slope upward toward the upwind side of the cooling air, forming a cooling air downward guide surface 8 (see Figure 3).

The fuel tank 4 thus formed is attached to the fan case 2 whose bottom surface is securely fixed to the engine using a tank stay 11 whose both ends are secured with bolts 19.

In this way, when the fuel tank 4 is attached close to the flywheel fan 3, a cooling air cutoff point C is formed in a part of the air guide surface 7. fuel tank 4
The outer peripheral portion of the flywheel fan 3 other than the air guide surface 7 is covered with a thin air guide plate 15.

Further, a tank stay 11 for attaching the fuel tank 4 to the fan case 2 is provided with an air leak prevention plate 9, as shown in FIGS. 3 and 4.

The leakage prevention plate 9 is formed by bending a thin plate into a dogleg shape, and is attached to the lower surface of the tank stay 11 by spot welding. A head cowling 1 that covers the cylinder 13 and the cylinder head 14 directs the cooling air flowing through the ventilation space 10 formed by the cylinder 13 and the cylinder head 14.
2 and upper edge 12a of the head cowling 12.
This prevents the cooling air from leaking to the outside from the gap S between the bottom surface 4b of the fuel tank 4 and the bottom surface 4b of the fuel tank 4.

This allows a large amount of cooling air to be blown onto the engine without waste, improving cooling performance.

In the above embodiment, the leak prevention plate 9 is fixed to the tank stay 11 by spot welding, but instead of spot welding, it may be fixed with bolts or adhesive, or the tank stay It may be formed integrally with 11.

The present invention is constructed and operates as described above, and thus has the following effects.

That is, by providing the fuel tank in the fan case alongside the cooling fan, the overall external size of the engine can be significantly reduced. In addition, when the engine is made smaller in this way, the leakage prevention plate prevents engine cooling air from leaking out from the gap created between the bottom surface of the fuel tank and the upper edge of the head cowling. Since cooling air is blown onto the engine, engine cooling performance is greatly improved.

In addition, the leakage prevention plate has a simple structure of being directly installed on the tank stay, does not require a dedicated support device, and can be implemented at low cost.

In addition, the fuel tank is cooled by a large amount of cooling air generated by the cooling fan, and the fuel in the fuel tank is kept at a low temperature, eliminating the risk of fire due to fuel evaporation, and reducing the risk of fire in the fuel supply path. can effectively prevent vapor lock.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a perspective view of a forced air-cooled vertical shaft engine, FIG. 2 is a cross-sectional plan view, FIG. 3 is a longitudinal sectional view, and FIG. 4 is a tank stay FIG. 5 is a perspective view corresponding to FIG. 3 showing a conventional example. S... Gap, 1... Engine, 2... Fan case, 3... Centrifugal fan, 4... Fuel tank, 5
...Crankcase, 9...Leakage prevention plate, 10...
...Ventilation space, 11... Tank stay, 12... Head cowling, 12a... Upper edge of 12, 13...
...Cylinder, 14...Cylinder head.

Claims (1)

[Scope of utility model registration request] A cylinder cooling fan 3 is placed on the crankcase 5 of the vertical shaft engine 1, and a fuel tank 4 is placed above the cylinder 13. 11 to the fan case 2,
Head cowling 12 that covers the cylinder head 14
The upper edge 12a of is located directly below the fuel tank 4,
The cooling air sent out from the fan 3 is transferred to the fuel tank 4.
It is configured to blow down from the lower ventilation space 10 to the cylinder 13 and cylinder head 14, and the lower surface of the fuel tank 4 and the upper edge 12 of the head cowling 12.
A leakage prevention plate 9 is positioned in front of the upper edge 12a of the head cowling 12 and is fixedly attached to the tank stay 11. Forced air cooling system for vertical shaft engines.