JPH0726532B2 - Forced air cooling system for engine - Google Patents

Description

The present invention relates to an air cooling device for a forced air cooling engine.

<Prior Art> Generally, as an air-cooling device for a forced air-cooled engine, an engine cooling centrifugal fan is provided on the front side of the crankcase, and the engine cooling centrifugal fan is fixed to a forward rotation shaft protruding forward from the crankcase to cool the engine. The fan case of the centrifugal fan for the engine faces the cylinder and the cylinder head, and opens rearward so that the cooling air generated by the centrifugal fan for cooling the engine flows from the fan case to the heat dissipation surface of the cylinder and the cylinder head from the front to the back. The one configured to blow through is often used.

<< Problems to be Solved by the Invention >> In the above air-cooling device, the cooling air from the centrifugal fan provided on the front side of the crankcase is only unilaterally sent to the cylinder and the cylinder head through the fan case. In addition, the cooling air does not necessarily spread sufficiently to the back side of the cylinder and the cylinder head, and there is a large difference in cooling performance between the front side and the back side, and thermal strain easily occurs due to the temperature drop. Further, in order to solve such a problem, an air guide cover is provided up to the back of the cylinder and the cylinder head so that the cooling air can spread to the back, but the cooling air passage is greatly bent. There was a problem that the ventilation resistance increased and the overall cooling effect did not increase so much.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and provide a forced air cooling device capable of efficiently cooling even the back of an engine.

<< Means for Solving Problems >> In order to achieve the above object, the present invention provides, for example, FIG.
As shown in FIG. 3, it is configured as follows.

That is, the engine cooling centrifugal fan 4 is provided in front of the crankcase 1 of the forced air cooling engine E, and the engine cooling centrifugal fan 4 is fixed to the crankshaft 2 protruding forward from the crankcase 1, and the engine cooling centrifugal fan 4 is fixed. The fan case 7 of the fan case 7 is opened rearward so as to face the cylinder 5 and the cylinder head 6, and one side portion of the cylinder 5 and the cylinder head 6 is covered with the air guide cover 9 and raised by the engine cooling centrifugal fan 4. The cooled cooling air is first guided by the fan case 7 to flow laterally to one side on the front surfaces of the cylinder 5 and the cylinder head 6, and then guided by the wind guide cover 9 to laterally move the cylinder 5 and the cylinder head 6. After blowing one side from front to back, blow out the rear surfaces of the cylinder 5 and the cylinder head 6 from one lateral end to the other lateral side. In the forced air cooling system of the engine, the centrifugal fan 11 for exhaust air, which cools the cylinder 5 and the cylinder head 6 and discharges the cooled exhaust air whose temperature has risen, is located behind the crankshaft 1 and behind the crankshaft 2. A rotary shaft which is provided at a position deviated to the other side and is positioned away from the wind guide cover 9 located on one lateral side of the crankcase 1 so that the exhaust fan centrifugal fan 11 projects rearward from the crankcase 1. An air intake case 12 that is fixed to 10 and guides the cooling exhaust air of the cylinder 5 and the cylinder head 6 to the exhaust air centrifugal fan 11 is installed from the back of the cylinder 5 and the cylinder head 6 to the air intake port 14 of the exhaust air centrifugal fan 11. The exhaust fan 15 is characterized in that the exhaust fan 15 of the exhaust fan 11 is configured to open downward in the lower part of the air intake case 12.

<< Operation >> The present invention operates as follows.

The cooling air generated by the engine cooling centrifugal fan 4 is first guided by the fan case 7, flows laterally to one side across the front surfaces of the cylinder 5 and the cylinder head 6, and then is guided by the wind guide cover 9. After one side surface of the cylinder 5 and the cylinder head 6 is blown from the front to the back, the back surface of the cylinder 5 and the cylinder head 6 is blown from one side end to the other side.

The blown cooling air is guided by the air intake case 12,
It is sucked out by the centrifugal fan 11 for exhaust air and discharged downward from the exhaust port 15.

<< Effects of the Invention >> The present invention is configured and operates as described above,
It has the following effects.

(B) Prevention of thermal distortion of cylinder and cylinder head This exhaust air centrifugal fan 11 strongly sucks out only the engine cooling air, so that the amount of engine cooling air greatly increases.

Moreover, when the large amount of cooling air flows through the rear surfaces of the cylinder 5 and the cylinder head 6 from one lateral end to the other lateral side, the rear surface deviated to the lateral other side than the position of the crankshaft 2. Since it flows excessively to a part, it cools its back surface strongly over a wide surface.

As a result, the rear surfaces of the cylinder 5 and the cylinder head 6 are also strongly cooled, so that the temperature difference between the rear surface and the front surface is small, and thermal strain is unlikely to occur.

(B) High cooling efficiency of the engine The cooling air blown from the rear part of the wind guide cover 9 to the rear surfaces of the cylinder 5 and the cylinder head 6 directly absorbs air from the air intake case 12.
Guided by and is smoothly sucked out by a short distance exhaust centrifugal fan 11 at a short distance.

Therefore, the ventilation resistance of the centrifugal fan 11 for exhaust air is small. Moreover, the ventilation resistance of the engine cooling fan 4 is also small. As a result, the cooling efficiency resistance of the engine is high.

(C) A small suction fan is sufficient. The centrifugal fan 11 for exhaust air sucks in only the engine cooling exhaust air, and does not use other gases (for example, cooling exhaust air of equipment driven by the engine or engine exhaust air). (Exhaust gas of) is not sucked in, so the required air flow is small.

In addition, the exhaust fan 11 has a small air intake resistance and a high air blowing efficiency as described above.

As a result, the exhaust fan centrifugal fan 11 need only be small,
For its cooling capacity, the external shape of the engine can be made smaller and the implementation cost can be reduced.

(D) Quieting of the forced air-cooled engine The engine noise leaked to the back of the engine E passes through the air intake port 14 from inside the fan case 12 and is reflected back and forth in the centrifugal fan chamber housing the exhaust fan 11. After repeating,
The air is discharged downward from the exhaust port 15 at the bottom of the exhaust port 15 and leaks into the atmosphere.

In this way, the engine noise is absorbed and interferes greatly while being repeatedly reflected back and forth in the centrifugal fan chamber, and is greatly attenuated and reduced, so that the amount of leakage into the atmosphere is reduced, Excellent soundproofing performance.

Moreover, the engine noise, which has been greatly attenuated and reduced, leaks downward, and is absorbed by the engine mounting base and the ground below it, and does not diffuse horizontally or upward, so it is hard to reach the human ear. , Forced air-cooled engine can be significantly quieter.

(E) Achieving both quietness and improvement of air blowing efficiency The fan blown air discharged from the centrifugal fan 11 for exhaust air is pressure-fed in the centrifugal direction and smoothly guided inside the centrifugal fan chamber, and is discharged from the exhaust port 15 to the atmosphere. Unlike the case of using the axial fan, the fan pressure blown air does not collide with the rear end wall of the fan chamber and a large pressure loss does not occur.

As a result, it is possible to sufficiently achieve both the above-mentioned "(d) Quieting of the forced air-cooled engine" and the improvement of the ventilation efficiency of the centrifugal fan 11 for exhaust air.

<< Examples >> FIG. 1 shows a longitudinal side surface of a forced air cooling system for an engine according to the present invention, FIG. 2 shows a plane thereof, and FIG. 3 shows a rear surface thereof.

The front end of the crankshaft 2 is projected at the center of the front surface of the crankcase 1 of the forced air cooling engine E, the flywheel 3 is connected thereto, and the centrifugal fan 4 for engine cooling is integrally formed on the front surface of the flywheel 3. Has been done.
Then, a fan case 7 for guiding the cooling air generated by the centrifugal fan 4 to the front parts of the cylinder 5 and the cylinder head 6.
Is attached to the front of the engine, and a recoil starter 8 linked to the crankshaft 2 is attached to the front of the fan case 7.

On one side of the cylinder 5 and the cylinder head 6, there is provided an air guide cover 9 connected to a rearward air outlet of the fan case 7 so that the cooling air from the centrifugal fan 4 can be directed to the heat radiating surface of the cylinder 5 and the cylinder head 6. After the air is blown from the rear side to the rear side, the rear surfaces of the cylinder 5 and the cylinder head 6 are blown out from one lateral end toward the other lateral side.

On the rear side of the crankcase 1, a camshaft 10 is projected as an output shaft at a position deviated laterally and laterally from the crankshaft 2, and the camshaft 10 has an exhaust air centrifugal fan. 11 is stuck. Further, on the rear side of the crankcase 1, there is provided an air intake case 12 for guiding the cooling exhaust air coming out from the rear outlet of the air guide cover 9 to the exhaust air centrifugal fan 11.

The air suction case 12 has a suction port 14 for a centrifugal fan 11 for exhaust air formed in a partition wall 13 provided therein,
The lower part of the air intake case 12 is opened downward as an air exhaust port 15.

According to the forced air cooling device configured as described above, the cooling air that has blown through the cylinder 5 and the cylinder head 6 from the front to the rear by the centrifugal fan 4 for cooling the engine is supplied from the rear outlet of the air guide cover 9 to the cylinder 5 and the cylinder. While wrapping around the back of the head 6, it is guided by the air intake case 12, is sucked into the air intake port 14 of the air exhaust centrifugal fan 11, and is discharged downward from the lower air exhaust port 15 of the air intake case 12.

FIG. 4 shows an engine E equipped with such a forced cooling device.
FIG. 2 is a schematic side view of a riding-type rice transplanter as an example of a working machine equipped with a vehicle, in which an output pulley 16 attached to the camshaft 10 and an input pulley (not shown) of a mission case are belt-transmitted. In this case, since the cooling exhaust air is guided and discharged downward by the air intake case 12, even when the spare seedling is accommodated and mounted on the outer side of the engine E, the exhaust seed heat does not cause heat loss to the spare seedling.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an example of an engine forced air cooling device according to the present invention, FIG. 2 is a partially cutaway plan view, FIG. 3 is a partially cutaway rear view, and FIG. 4 is an engine. It is a schematic side view which shows the riding rice transplanter as an example of a mounting working machine. 1 ... Crank case, 2 ... Crank shaft, 4 ... Centrifugal fan for engine cooling, 5 ... Cylinder, 6 ... Cylinder head, 7 ... Fan case, 9 ... Wind guide cover, 10 ... Rotating shaft , 11 …… Centrifugal fan for exhaust air, 12 …… Air intake case, 14 …… Air intake, 15 …… Air exhaust, E…
…engine.

Claims (1)

[Claims] 1. A centrifugal fan (4) for engine cooling is provided on the front side of a crankcase (1) of a forced air cooling engine (E), and the centrifugal fan (4) for engine cooling is projected forward from the crankcase (1). Fan case (7) for centrifugal fan (4) for engine cooling, fixed to crankshaft (2)
The rear side of the cylinder (5) and the cylinder head (6) is covered with a wind guide cover (9) so that the blower opening of the engine faces the cylinder (5) and the cylinder head (6) and is opened rearward to cool the engine. The cooling air generated in the centrifugal fan (4) for use in the air is first guided by the fan case (7) and flows laterally to one side across the front surfaces of the cylinder (5) and the cylinder head (6), and then the air guide cover. After being guided by (9) and blowing one lateral side of the cylinder (5) and the cylinder head (6) from front to back, the rear side of the cylinder (5) and the cylinder head (6) is lateral In a forced air-cooling device for an engine configured to blow out from one end to the other lateral side, a centrifugal fan for exhaust air () that cools the cylinder (5) and the cylinder head (6) and discharges the temperature-increased cooling exhaust air ( 11)
On the rear side of the crankcase (1) on the crankshaft (2)
It is provided at a position deviated laterally to the other side, and is positioned away from the wind guide cover (9) located on the lateral one side of the crankcase (11). An air intake case (12) that is fixed to a rotating shaft (10) that projects rearward from 1) and guides cooling exhaust air of the cylinder (5) and cylinder head (6) to an exhaust air centrifugal fan (11).
Is provided from the back of the cylinder (5) and the cylinder head (6) to the air intake port (14) of the air exhaust centrifugal fan (11), and the air exhaust port (15) of the air exhaust centrifugal fan (11) is provided. A forced air cooling system for the engine, which is configured by opening downwards at the bottom of the air intake case (12).