JP2002371846A - Cooling device for air cooled engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for an air cooled engine capable of increasing cooling effect of an oil pan constituent part of a crank case while maintaining high cooling performance of a cylinder and a cylinder head and suppressing the rise of a temperature of lubricating oil in the crank case to improve lubrication performance of lubricating oil. SOLUTION: This cooling device for the air cooled engine is constituted in such a way that a cylinder part is cooled by cooling air passing through a cooling air passage by a cooling fan driven by a crank shaft, the cooling air passage is branched into two cooling air passages by a partition member, the cooling air passing through the first cooling air passage on one side is led into the cylinder part, and the cooling air passing through the second cooling air passage on the other side is led into a third cooling air passage facing an external wall of the crank case to cool the external wall of the crank case.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cooling device in an air-cooled general-purpose engine, which is configured to cool a cylinder portion by cooling air sent by a cooling fan driven directly to a crankshaft. About.

[0002]

2. Description of the Related Art FIGS. 3 and 4 show a cooling fan, which is directly connected to a crankshaft and is driven from a cooling air inlet of a fan cover through a cooling air passage provided on an outlet side of the cooling fan. FIG. 3 shows a conventional example of an air-cooled engine configured to cool the cylinder part by feeding it to a cylinder part, and FIG.
FIG. 4 is a sectional view taken along line BB of FIG.

[0003] In the drawing, 1 is a crankcase, 2 is a cylinder, 3 is a cylinder head, and a plurality of cooling fins 4 are provided on the outer surface of the cylinder 2 and the outer surface of the cylinder head 3.
Is protruding. A crankshaft 5 has a flywheel 7, a cooling fan 6 integral with the flywheel 7, a starting pulley 8 fixed to the cooling fan 6, and a recoil starter 9 fixed to the front end of the crankshaft. ing. The flywheel 7, the cooling fan 6, the starting pulley 8 fixed to the cooling fan 6, the recoil starter 9, and the like are housed in a fan cover 11 fixed to a front portion of the crankcase 1.

A cooling air inlet 10 is formed in the recoil starter 9 at one or more holes in front of the cooling fan 6. Reference numeral 33 denotes a spiral chamber formed inside the fan cover 11 and formed in an annular shape along the outer periphery of the cooling fan 6. Reference numeral 32 denotes a nose portion serving as a cooling air inlet of the spiral chamber 33. The spiral chamber 33 has a flow passage area gradually increasing from the nose portion 32 to the lower portion of the fan cover 11.

In an air-cooled engine provided with such a cooling device, when the engine is started by the recoil starter 9, the cooling fan 6 rotates together with the crankshaft 5,
External air (cooling air) is sucked into the fan cover 11 from the cooling air inlet 10 and flows into the spiral chamber 33 from the nose portion 32 as shown by arrows in FIGS. The cooling air is swirled by the rotation of the cooling fan 6.
The pressure is increased in the cylinder 3 and the air is sent to the cylinder 2 and the cylinder head 3 side, flows between the cooling fins 4, cools the cylinder 2 and the cylinder head 3, and is discharged to the outside air.

In Japanese Patent Publication No. Hei 7-15256, cooling air discharged from a cooling fan is divided into two systems, and one of the two is discharged from a first exhaust port to the outside of a cover.
There is disclosed an air-cooled engine configured to supply the other flow from a second exhaust port to an exhaust muffler device to reduce noise diffused around the engine. Japanese Patent Application Laid-Open No. 2000-303835 further discloses that cooling air is divided into two systems by a guide plate at an outlet of a fan cover, and a cylinder and a cylinder head are each cooled by a different system of cooling air to improve the cooling effect of these high-temperature members. An air-cooled engine is disclosed.

[0007]

However, FIGS.
In the air-cooled engine equipped with the cooling device shown in
Since the flow area of the spiral chamber 33 is narrowed in the lower part of the crankcase 1, the flow resistance increases in this part, and the flow loss of the cooling air flowing from the nose part 32 into the spiral chamber 33 increases. The cooling effect on the cylinder 2 and cylinder head 3 side is reduced.

In the prior art, the cooling of the oil pan portion regulated at the lower portion of the crankcase 1 is performed only by the cooling function of natural convection of the air flowing along the outer surface of the outer wall of the crankcase 1, and the engine is cooled. It is not possible to cope with the increase in lubricating oil temperature due to the increase in output and miniaturization and weight reduction of lubricating oil. This may cause wear and seizure of the lubricating member.

In Japanese Patent Publication No. Hei 7-15256, the cooling air is divided into two systems, and the exhaust muffler is cooled by one of the two systems to reduce the noise diffused around the engine. And JP-A-2000-30
No. 38 merely divides the cooling air into two systems and cools the cylinder and the cylinder head with the cooling air of different systems to enhance the cooling effect of both. No appropriate measures have been taken to increase the temperature.

The present invention has been made in view of the problems of the prior art,
Air cooling that can increase the cooling effect of the oil pan components of the crankcase while keeping the cooling performance of the cylinder and cylinder head high, and suppress the rise in the lubricating oil temperature in the crankcase to improve the lubricating oil lubrication performance. An object of the present invention is to provide an engine cooling device.

[0011]

According to the present invention, a cooling air introduced from a cooling air inlet of a fan cover by a cooling fan directly connected to a crankshaft is provided. In a cooling device for an air-cooled engine configured to cool the cylinder portion by feeding it to a cylinder portion through a cooling air passage provided on an outlet side of the cooling fan.
A third cooling air passage that branches into two cooling air passages, guides the cooling air that has passed through the first cooling air passage on one side to the cylinder portion, and directs the cooling air that has passed through the second cooling air passage on the other side to the outer wall of the crankcase. A cooling device for an air-cooled engine, wherein the cooling device is configured to be guided to a cooling air passage for cooling an outer wall of the crankcase.

The invention according to claims 2 to 4 relates to a specific configuration of the cooling air passage, and the invention of claim 2 relates to claim 1.
In the above, the first and second two cooling air passages are formed by dividing an annular spiral chamber formed along an outer peripheral portion of the cooling fan into two by the partition member extending in a circumferential direction. It is characterized by.

According to a third aspect of the present invention, in the second aspect, the cooling air sent from the cooling fan is supplied to the respective cooling air inlets of the first and second cooling air passages. A nose portion leading to the passage is provided.

According to a fourth aspect of the present invention, in the first aspect, the third cooling air passage is formed along a guide member fixed to an outer wall of an oil pan portion of the crankcase.

According to a fifth aspect of the present invention, in the first aspect,
A cooling fin protruding into the third cooling air passage is fixed to an outer wall of the crankcase.

According to this invention, the cooling air that has passed through the second cooling air passage is guided to the third cooling air passage that faces the outer wall of the crankcase, and cools the oil pan of the crankcase. The lubricating oil stored in the oil pan is forcibly cooled by the cooling air flowing through the third cooling air passage, so that the temperature rise of the lubricating oil in the crankcase and the oil pan is suppressed.

In particular, while the cooling air in the third cooling air passage is caused to flow through the cooling air passage by the guide member as in claim 4, it protrudes from the outer wall of the crankcase as in claim 5. By contacting the cooling fins, the cooling air flows reliably along the outer wall without being diffused, and the cooling fins increase the heat transfer area on the crankcase side, further improving the cooling effect of the crankcase portion. improves. By avoiding the high temperature of the lubricating oil in the crankcase 1, deterioration of lubrication performance of lubricating members such as the main bearing and other moving parts is prevented, and wear and seizure of the lubricating members are prevented. Is done.

Further, the flow path of the cooling air is firstly divided by a partition member.
The decrease in the amount of cooling air distributed to the cylinder and the cylinder head due to the two channels of the cooling air passage and the second cooling air passage is reduced along the partition member formed in a spiral shape and extending in the circumferential direction. The cooling air can be avoided by flowing the cooling air to the cylinder and the cylinder head side, whereby the crankcase and the oil pan can be efficiently cooled while maintaining the cooling performance on the cylinder and the cylinder head side.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not merely intended to limit the scope of the present invention, but are merely illustrative examples unless otherwise specified. Absent.

FIG. 1 is a front view of an air-cooled engine according to an embodiment of the present invention as viewed from the front side, and FIG. 2 is a sectional view taken along line AA of FIG. 1 and 2, reference numeral 1 denotes a crankcase, 2 denotes a cylinder, 3 denotes a cylinder head, and a plurality of cooling fins 4 project from an outer surface of the cylinder 2 and an outer surface of the cylinder head 3. A crankshaft 5 has a flywheel 7, a cooling fan 6 integrated with the flywheel 7, a starting pulley 8 fixed to the cooling fan 6, and a recoil starter 9, which are fixed to the front end thereof in the axial direction. I have.

In this embodiment, the cooling fan 6 is a radial fan that draws in air from the inner peripheral side of the fan and discharges it to the outer peripheral side. However, other types of fans may be used. The flywheel 7, the cooling fan 6, the starting pulley 8 fixed to the cooling fan 6, the recoil starter 9, and the like are housed in a fan cover 11 fixed to a front portion of the crankcase 1. Reference numeral 10 denotes a cooling air inlet, and one or a plurality of holes are perforated in a portion of the recoil starter 9 in front of the cooling fan 6. The basic configuration described above is the same as the conventional configuration shown in FIGS.
In the present invention, the cooling air passage through which the cooling air sent from the cooling fan flows and the bottom of the crankcase are improved.

That is, in FIGS. 1 and 2, 15 and 16 divide a spiral chamber 13 on the cooling air outlet side of the cooling fan 6 into two flow paths by a guide plate (partition member) 14 formed in a spiral shape. This is a cooling air passage formed. The cooling air passages 15 and 16 are formed between the first cooling air passage 16 on the inner peripheral side and the outer periphery by the guide plate 14 extending in the circumferential direction through the annular spiral chamber 13 formed along the outer peripheral portion of the cooling fan 6. And the second cooling air passage 15 on the side.

A first nose portion 12 is formed between an inner surface of the fan cover 11 and an outer peripheral portion of the cooling fan 6;
Reference numeral 17 denotes a second nose portion formed between the inner surface of the guide plate 14 and the outer peripheral portion of the cooling fan 6, and the first nose portion 12 is provided with the first and second cooling air passages 16 and Fifteen
, The second nose portion 17 constitutes the passage minimum area portion of the first cooling air passage 16, and the first nose portion 12 is smaller than the second nose portion 17. The cooling fan 6 is formed with a phase at a predetermined angle upstream in the rotation direction N (see FIG. 1) of the cooling fan 6, and the spiral chamber 13 is formed between the phases.

The downstream side of the first cooling air passage 16 communicates with a cylinder cooling air passage 016 to the cylinder 2 and the cylinder head 3, and the downstream side of the second cooling air passage 15 is described later. The cooling air passage 40 communicates with the third cooling air passage 41 through the discharge port 40. Reference numeral 41 denotes a third cooling air passage, which is in contact with an oil pan portion 101 of the crankcase 1 in which lubricating oil is stored, and which has a bottom wall 1a of the crankcase 1 and a guide plate 18 fixed to the bottom wall 1a. It is formed in a tunnel-like shape surrounded by. As described above, the third cooling air passage 41 and the outlet end of the second cooling air passage 15 communicate with each other through the outlet 40. Reference numeral 20 denotes a cooling fin protruding into the third cooling air passage 41,
A plurality of them are fixed to the bottom wall 1a of the crankcase and extend in the direction of the crankshaft 100.

When the engine is started by the recoil starter 9 in the air-cooled engine provided with the cooling device having the above-described configuration, the cooling fan 6 rotates clockwise (in the direction of the arrow N) together with the crankshaft 5, and external air ( Cooling air) is sucked into the fan cover 11 from the cooling air inlet 10 and is sent out from the outer periphery of the cooling fan 6 as shown by an arrow in FIG. The cooling air that has flowed into the spiral chamber 13 is branched from the inside of the spiral chamber 13 into a first cooling air passage 16 to be described later and a second cooling air passage 15 that is guided into the second cooling air passage 15. The cooling air that has flowed into the second cooling air passage 15 is guided inside the second cooling air passage 15 by the outer surface of the spiral guide plate 14 as shown by the arrow in FIG. And flows into the third cooling air passage 41 from the outlet 40.

The cooling air introduced into the third cooling air passage 41 is guided by the guide plate 18 and
While flowing between the plurality of cooling fins 20 protruding from the bottom wall 1a, the lubricating oil stored in the crankcase 1 itself and the oil pan 101 is cooled through the cooling fins 20 and the bottom wall 1a. Therefore, according to this embodiment, the cooling air passing through the second cooling air passage 15 is guided to the third cooling air passage 41 facing the bottom wall 1a (outer wall) of the crankcase 1, and the oil pan of the crankcase 1 Since the cooling unit 101 is cooled, the lubricating oil stored in the crankcase 1 itself and the oil pan unit 101 is forcibly cooled by the cooling air flowing through the third cooling air passage 41, and the crankcase 1 and the oil are cooled. The temperature rise of the lubricating oil in the pan 101 is suppressed.

In particular, the cooling air in the third cooling air passage 41 is caused to flow through the cooling air passage 41 by the guide plate 18 and to the cooling fins 20 projecting from the bottom wall 1 a of the crankcase 1. Since the cooling air flows, the cooling air flows along the bottom wall 1a without diffusion, and the heat transfer area on the crankcase 1 side is enlarged.
The cooling effect of the part is further improved. By avoiding the high temperature of the lubricating oil in the crankcase 1, deterioration of lubrication performance of lubricating members such as the main bearing and other moving parts is prevented, and wear and seizure of the lubricating members are prevented. Is done.

On the other hand, the cooling air guided from the inside of the spiral chamber 13 to the first cooling air passage 16 through the nose portion 17 is directed to the spirally formed guide plate 14 by the rotation of the cooling fan 6. Along the cylinder 2 and the cylinder head 3, the pressure is increased while the pressure is increased, and is sent to the side of the cylinder 2 and the cylinder head 3 to flow between the cooling fins 4.

Therefore, according to this embodiment, the spiral chamber 1
The flow path of the cooling air from the first cooling air passage 16 and the second cooling air passage
The two cooling air passages 15 reduce the amount of cooling air distributed to the cylinder 2 and the cylinder head 3 side.
4 can be avoided by flowing cooling air through the cylinder cooling air passage 016 to the cylinder 2 and the cylinder head 3 side, thereby maintaining the cooling performance of the cylinder 2 and the cylinder head 3 while maintaining the cooling performance. The case 1 and the oil pan unit 101 can be efficiently cooled.

[0030]

As described above, according to the present invention, the cooling air is guided to the third cooling air passage facing the outer wall of the crankcase and cools the oil pan of the crankcase. The lubricating oil stored in the pan portion is forcibly cooled by the cooling air flowing through the third cooling air passage, and the temperature rise of the lubricating oil in the crankcase and the oil pan portion is suppressed.

In particular, while the cooling air in the third cooling air passage is passed through the cooling air passage by the guide plate as in claim 4, the cooling air projects from the outer wall of the crankcase as in claim 4. By contacting the cooling fins, the cooling air flows reliably along the outer wall without being diffused, and the cooling fins increase the heat transfer area on the crankcase side, further improving the cooling effect of the crankcase portion. improves. By avoiding the high temperature of the lubricating oil in the crankcase 1, deterioration of lubrication performance of lubricating members such as the main bearing and other moving parts is prevented, and wear and seizure of the lubricating members are prevented. Is done.

The flow of the cooling air is divided into two channels by the partition member, so that the amount of the cooling air distributed to the cylinder and the cylinder head side is reduced. The cooling air is distributed along the partition member extending in the circumferential direction. This can be avoided by allowing the fluid to flow to the cylinder and the cylinder head side, whereby the crankcase and the oil pan can be efficiently cooled while maintaining the cooling performance of the cylinder and the cylinder head side.

[Brief description of the drawings]

FIG. 1 is a front view of an air-cooled engine according to an embodiment of the present invention as viewed from the front side of the engine.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a front view of an air-cooled engine showing a conventional technique as viewed from the front side of the engine.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crankcase 1a Bottom wall 2 Cylinder 3 Cylinder head 4 Cooling fin 5 Crankshaft 6 Cooling fan 7 Flywheel 8 Starting pulley 9 Recoil starter 10 Cooling air inlet 11 Fan cover 12 Nose part 13 Spiral chamber 14 Guide plate 15 Second Cooling air passage 16 First cooling air passage 17 Nose portion 18 Guide plate 20 Cooling fin 40 Discharge port 41 Third cooling air passage 101 Oil pan portion

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyoshi Kawachi 1 Ishizuka-cho, Iwazuka-cho, Nakamura-ku, Nagoya F-term in the Industrial Equipment Division, Mitsubishi Heavy Industries, Ltd. (Reference) 3G024 AA64 AA69 BA06 CA19 CA20 CA23 CA24 CA26

Claims (5)

[Claims] 1. A cooling fan, which is directly connected to a crankshaft and driven by a cooling fan, sends cooling air introduced from a cooling air inlet of a fan cover to a cylinder through a cooling air passage provided on an outlet side of the cooling fan. In a cooling device for an air-cooled engine configured to cool a cylinder portion, the cooling air passage is branched into two cooling air passages by a partition member, and cooling air that has passed through a first cooling air passage on one side is cooled by the cylinder. A cooling air passing through the second cooling air passage on the other side and leading to a third cooling air passage facing the outer wall of the crankcase to cool the outer wall of the crankcase. Engine cooling system. 2. The first and second two cooling air passages,
The cooling device for an air-cooled engine according to claim 1, wherein an annular spiral chamber formed along an outer peripheral portion of the cooling fan is divided into two by the partition member extending in a circumferential direction. 3. A nose portion for guiding cooling air sent from the cooling fan to the first and second cooling air passages is provided at each of the cooling air inlets of the first and second cooling air passages. 3. The cooling device for an air-cooled engine according to claim 2, wherein: 4. The cooling device for an air-cooled engine according to claim 1, wherein said third cooling air passage is formed along a guide member fixed to an outer wall of an oil pan portion of said crankcase. . 5. The cooling device for an air-cooled engine according to claim 1, wherein cooling fins projecting into the third cooling air passage are fixed to an outer wall of the crankcase.