JPH0642347A - Forced air-cooling device for engine - Google Patents

Abstract

PURPOSE:To uniformly cool the periphery of a cylinder bore by improving a flow of cooling air in a cooling air passage of surrounding the periphery of the cylinder bore. CONSTITUTION:In a forced cooling device 33 for an engine provided with a cooling air passage 17 of surrounding the periphery of a cylinder bore 10 of providing an exhaust port 18, air blowing means 32 for introducing cooling air into this cooling air passage 17 and a release port 40 for connecting the cooling air passage 17 to the outside, a closing part 37 is formed in the cooling air passage 17 in a side of the exhaust port 18, to provide a mounting part 39 of the air blowing means 32 in one side of this closing part 37 and to form the release port 40 in the other side of the closing part 37.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forced air cooling system for an engine which has an improved cooling effect on a cylinder.

[0002]

2. Description of the Related Art In an air-cooled engine for a motorcycle,
There is a cylinder block and a cylinder head that are installed horizontally or tilted largely to reduce the overall height of the engine. When such an engine is naturally air-cooled by the running wind, the running wind hits the cylinder head well, but the running wind does not hit the cylinder block hidden behind the cylinder head so much that the cylinder bore formed in the cylinder block Had a tendency to overheat.

Therefore, a forced air cooling device has been put into practical use in which a cooling air passage surrounding the cylinder bore is formed and cooling air is introduced into the cooling air passage to forcibly cool the cylinder bore. 8 (a), (b), (c)
Shows a conventional example of a cylinder block which is a main part of such a forced air cooling device.

This cylinder block 100 has, for example, 2
For a cycle engine, with a cylinder bore 1 in the center
01 is formed, and the cylinder bore 101 is formed on the outer periphery thereof.
Cooling fins 102 extending in a direction orthogonal to the axis of the
Are formed.

The outer periphery of the cooling fin 102 has a wall portion 10.
3, 104, the cap 105, and the air duct 106, whereby the cylinder bore 101 is covered.
A cooling air passage 107 that surrounds the outer periphery of is formed. Note that, for example, the wall portions 103 and 104 are integrally formed with the cooling fin 102.

An exhaust port 108 extends outward from an intermediate portion of the cylinder bore 101 and passes through the wall 104, and a plurality of discharge ports 109 are formed in the wall 104 near the exhaust port 108. There is. These outlets 1
09 is provided between the cooling fins 102, and is arranged on the opposite side of the air duct 106 across the exhaust port 108.

The air duct 106 is a part of a blower (not shown), and the cooling air blown from the blower is introduced into the cooling air passage 107 through the air duct 106. This cooling air is divided into two directions as shown by arrows A and B, and after cooling the cylinder bore 101, the discharge port 10
9 is released to the outside.

[0008]

However, when the cooling air is split in the A and B directions in this way, the cooling air flow is good in the vicinity of the air duct 106, but near the point C where the A and B flows merge. Causes a vortex flow to deteriorate the flow of the cooling air and reduces the cooling effect near the point C. For this reason, the periphery of the cylinder bore 101 is not uniformly cooled, which may cause overheating.

Further, depending on the shape of the cooling air passage 107, there may be a portion where stagnation occurs in the flow of the cooling air, and there is a concern that the cooling effect in this portion may be significantly reduced.

In order to cover these problems, it is necessary to enlarge the blower means to increase the blower capacity, which inevitably results in a larger engine as a whole and a loss in output.

The present invention has been made to solve such a problem, and improves the flow of the cooling air in the cooling air passage surrounding the outer periphery of the cylinder bore to uniformly cool the periphery of the cylinder bore. It is an object of the present invention to provide a forced air cooling system for an engine capable of achieving the above.

[0012]

In order to achieve the above object, the forced air cooling system for an engine according to the present invention comprises:
As described in 1, the cooling air passage surrounding the outer circumference of the cylinder bore having the exhaust port, the blowing means for introducing the cooling air into the cooling air passage, and the discharge port for communicating the cooling air passage to the outside are provided. In a forced air cooling system for an engine, a closed portion is formed in the cooling air passage on the side of the exhaust port, a mounting portion for the blower is provided on one side of the closed portion, and the discharge port is formed on the other side of the closed portion. It was done.

Further, as described in claim 2, an adjusting port communicating with the outside is provided in the cooling air passage between the blower means and the closing part, and an opening area of the adjusting port is equal to an opening area of the discharge port. It is smaller.

Further, as described in claim 3, in the portion where the stagnation occurs in the flow of the cooling air in the cooling air passage, bypass holes are provided in cooling fins provided in multiple stages on the outer circumference of the cylinder bore, The spaces between the cooling fins are communicated with each other and the spaces are communicated with the outside.

[0015]

When the forced air cooling device of the engine is constructed as in claim 1, the cooling air introduced into the cooling air passage by the blowing means flows in the direction away from the closed portion without being divided into two directions, It is discharged to the outside from the discharge port after making one round around the cylinder bore.

Further, a forced air cooling device for the engine is claimed.
In such a configuration, of the cooling air introduced into the cooling air passage from the blower, a part of the cooling air that has flowed to the closed side is discharged to the outside through the adjustment port, and the remaining most of the cooling air is in the cylinder bore. It makes a round around the circumference and is discharged to the outside from the discharge port.

Further, when the forced air cooling device of the engine is constructed as described in claim 3, the cooling air in the portion where the stagnation occurs is discharged to the outside from the bypass hole and replaced with fresh air.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a right side view of a motorcycle equipped with an engine to which the present invention is applied. This motorcycle 1
Is generally called a business bike, and its engine 2 is an underbone type body frame 3
Since the cylinder block 4 and the cylinder head 5 are suspended horizontally, the cylinder block 4 and the cylinder head 5 are installed horizontally toward the front, and the overall height of the engine 2 is lowered. An exhaust muffler 6 extending rearward is connected to the lower surface of the cylinder block 4.

FIG. 2 is a cross sectional view of the engine 2 taken along the line II-II of FIG. 1, and FIG. 3 is an engine 2 taken along the line III-III of FIG.
FIG. The engine 2 is, for example, a two-cycle single-cylinder engine, and the cylinder block 4 and the cylinder head 5 are inserted from the front into four stud bolts 8 extending from the front surface of the crankcase 7 to the front.
A general assembly structure is adopted in which the cap nut 9 is fixed by fastening.

A cylinder bore 10 is formed in the center of the cylinder block 4, and a plurality of cooling fins 12 are formed on the outer circumference of the cylinder bore 10 and extend in a direction orthogonal to the axis of the cylinder bore 10. The outer periphery of these cooling fins 12 is the wall 1
3 and 14, a cap 15 and an air duct 16 which cover the cylinder bore 1.
The cooling air passage 17 surrounding 0 is airtight. Note that, for example, the wall portions 13 and 14 are integrally formed with the cooling fin 12.

An exhaust port 18 is formed so as to extend outward from an intermediate portion of the cylinder bore 10, and the exhaust muffler 6 is connected to the exhaust port 18.

The cylinder head 5 has a cylinder bore 10
A combustion chamber 20 that matches the above is provided as a recess, and an ignition plug 21 is screwed onto the top of the combustion chamber 20. Further, a large number of cooling fins 22 are erected on the head of the cylinder head 5 along the traveling direction of the motorcycle 1.

A piston 23 is slidably inserted in the cylinder bore 10, and the piston 23 is connected by a connecting rod 25 to a crankshaft 24 which is rotatably supported in the crankcase 7.

A magnet flywheel 26 is rotatably provided at one end of the crankshaft 24, and a magnet coil 27 located inside the magnet flywheel 26 is fixedly provided on a side surface of the crankcase 7.

A blower fan 28 is integrally provided on the outside of the magnet flywheel 26 so as to rotate integrally therewith, and a fan cowling 29 for covering the blower fan 28 is attached to the crankcase 7. Fan cowling 29
Extends forward and connects to the air duct 16. Also,
The fan cowling 29 is provided with a cooling air intake 30 that opens to the side of the blower fan 28.

The blower fan 28 and the fan cowling 2
9 and the air duct 16 constitute an air blowing means 32 for introducing cooling air into the cooling air passage 17, and the forced air cooling device is constituted by the air blowing means 32, the cooling air passage 17 and an outlet 40 described later. 33 are configured.

FIGS. 4A, 4B and 4C show the first embodiment of the present invention, showing a front view, a bottom view and a right side view of the cylinder block 4, respectively.

A stud bolt hole 34, through which the stud bolt 8 is inserted, is formed around the cylinder bore 10. The cap 15 is fastened to the boss 35 provided between the cooling fins 12 with a screw 36 or the like.

A blocking portion 37 is formed in the cooling air passage on the exhaust port 18 side. The closing portion 37 is configured by providing a partition wall 38 at a portion where the passage area of the cooling air passage 17 is narrowed by the exhaust port 18, for example.

The attachment part 39 of the blower means 32 is provided on one side of the closing part 37, and on the other side of the closing part 37, a discharge port 40 for communicating the cooling air passage 17 to the outside is formed. ing. A plurality of the discharge ports 40 are formed in the wall portion 14 so as to open between the cooling fins 12, and the opening area thereof allows the cooling air introduced into the cooling air passage 17 to be smoothly outside. It has a size that can be released to

When the engine 2 equipped with such a forced air cooling device 33 is operated, the blower fan 28 is rotated together with the crankshaft 7, and the outside air is cooled by the cooling air intake 30.
From the fan cowling 29. This air is introduced as cooling air into the cooling air passage 17 through the air duct 16.

Since the cooling air introduced into the cooling air passage 17 cannot proceed toward the closing portion 37, the closing portion 3
7 flows in a direction away from 7, and makes a round around the cylinder bore 10 and is discharged to the outside from the discharge port 40.

Since the cooling air flows in one direction in this way, the flow of the cooling air in the cooling air passage 17 is improved, the periphery of the cylinder bore 10 is uniformly cooled, and there is no fear of overheating. Therefore, it is not necessary to increase the blower capacity to increase the blower capacity as in the conventional case, and it is possible to reduce the size of the engine 2 as a whole and avoid output loss. Further, it becomes possible to cope with the high output of the engine 2 and the like.

5 (a), 5 (b) and 5 (c) are a front view, a bottom view and a right side view of a cylinder block 4A showing a second embodiment of the present invention, respectively.

In this cylinder block 4A, a closing portion 37 and a discharge port 40 similar to those of the cylinder block 4 shown in FIG. 4 are provided in the cooling air passage 17. The cooling air passage 17 is provided between the closing portion 37 and the blower 32.
An adjustment port 41 is provided for communicating with the outside. Similar to the discharge port 40, a plurality of the adjustment ports 41 are formed in the wall portion 14 so as to open between the cooling fins 12, and the opening area thereof is smaller than the opening area of the discharge port 40.

In the case of such a configuration, among the cooling air introduced into the cooling air passage 17 from the air blowing means 32, a part of the cooling air that has flowed to the closing portion 37 side is discharged to the outside from the adjusting port 41, Most of the remaining cooling air is cylinder bore 1
It goes around the circumference of 0 and is discharged from the discharge port 40 to the outside.

Therefore, the flow of the cooling air on the front side of the closing portion 37 (on the side of the blowing means 32) is further improved, and the periphery of the cylinder bore 10 can be cooled more uniformly.
Note that if the opening area of the adjusting port 41 is made too large, a large amount of cooling air will escape from the adjusting port 41, and the cooling air around the cylinder bore 10 will decrease, reducing the cooling effect. Is preferably large enough to allow some of the cooling air on the front side of the closed portion 37 to escape. Further, the position of the closing portion 37 may be a constricting portion without being closed, and a part of the cooling air on the adjusting port 41 side may flow to the discharging port 40 side.

FIGS. 6A, 6B, and 6C are a front view, a bottom view, and a right side view, respectively, of a cylinder block 4B showing a third embodiment of the present invention.

The cylinder block 4B is also provided with the closing portion 37 at the same position as the cylinder blocks 4 and 4A, but the discharge port 42 is provided not in the vicinity of the closing portion 37 but in the cap 43.

In the cylinder block 4B, the cooling air blown from the blowing means 32 makes a round in the cooling air passage 17 and is discharged to the outside from the discharge port 42. In such a structure, for example, the closing portion 37 is closed. Near (emission port 42
Stagnation of the cooling air may occur on the side) and the temperature of this part may rise.

Therefore, a bypass hole 44 is formed in each cooling fin 12 in the vicinity of the closed portion 37, and each cooling fin 1 is formed.
The spaces between the two are communicated with each other, and these spaces are communicated with the outside.

By virtue of such construction, the closing portion 3
The air in the vicinity of 7 passes through the bypass hole 44 and is discharged to the outside to be replaced with fresh air, so that the stagnation of the cooling air does not occur in the vicinity of the closed portion 37.

The installation position of the bypass hole 44 is not limited to the vicinity of the closed portion 37, and it may be installed at any place where stagnation of cooling air occurs. The opening area of the bypass hole 44 is determined by the installation position of the bypass hole 44, the amount of cooling air blown, and the like. Further, the closing part 37 may be configured as a contracting part.

FIGS. 7A, 7B and 7C are front views of a cylinder block 4C showing a modified example of the present invention, respectively.
It is a bottom view and a right side view.

In this cylinder block 4C, the cooling fins 1 other than the cooling fins 12a and 12b at both ends are provided.
2 is separated from the wall portion 14, and a communication passage 45 is formed between the cooling fin 12 and the wall portion 14. Also,
A discharge port 46 is provided in the wall portion 14, and a contracted flow portion 47 is formed between the discharge port 46 and the blowing means 32 by the exhaust port 18, for example.

With this structure, a part of the cooling air introduced from the blowing means 32 into the cooling air passage 17 flows to the side of the contracting portion 47, and the cooling fins 12 and 12a, The cooling air between the 12b is the communication passage 45.
To be a single flow, pass through the contracting portion 47, and are discharged from the discharge port 46 to the outside. Further, most of the remaining cooling air is exhausted to the outside through the exhaust port 46 after making a circuit around the cylinder bore 10.

The effect of providing the communication passage 45 in this way is that the adjusting port 4 of the cylinder block 4A shown in FIG.
1 is almost the same as the effect brought by 1, and the flow of the cooling air on the front side of the contracted flow section 47 (on the side of the blowing unit 32) can be improved.

Moreover, since the cooling fin 12 is separated from the wall portion 14, the shape of the discharge port 46 can be unified so as to have a simple shape.

The present invention can be applied not only to motorcycle engines but also to forced air cooling engines used for other purposes.

When an exhaust port is not provided in the cylinder bore as in a cylinder block for a 4-cycle engine, the partition wall 38 shown in FIG.
By forming the closing portion 37 by extending to the direction of 8,
The present invention can be applied.

[0052]

As described above, in the forced air cooling system for an engine according to the present invention, the cooling air passage surrounding the outer periphery of the cylinder bore having the exhaust port, and the blowing means for introducing the cooling air into the cooling air passage. In the forced air cooling device of the engine, which is provided with a discharge port that communicates the cooling air passage to the outside, a closed portion is formed in the cooling air passage on the exhaust port side, and one side of the blower of the blower means is formed on one side of the closed portion. A mounting portion is provided, and the discharge port is formed on the other side of the closing portion.

Therefore, the cooling air introduced into the cooling air passage by the blowing means flows in a direction away from the closed portion without splitting in two directions, makes a round around the cylinder bore, and goes out from the discharge port to the outside. Is released. Therefore, the flow of the cooling air in the cooling air passage is improved, the periphery of the cylinder bore is uniformly cooled, and the concern of overheating is eliminated.

Further, in the forced air cooling system for an engine according to the present invention, an adjusting port for communicating the cooling air passage to the outside is provided between the blower means and the closing part, and the opening area of the adjusting port is the outlet port. Since the opening area is smaller than the opening area, the flow of the cooling air on the blower means side of the closed portion is further improved, and the periphery of the cylinder bore can be cooled more uniformly.

Further, in the forced air cooling system for an engine according to the present invention, bypass holes are provided in the cooling fins provided in multiple stages on the outer circumference of the cylinder bore in the portion where stagnation occurs in the flow of the cooling air in the cooling air passage. Since the spaces between the cooling fins are communicated with each other and these spaces are communicated with the outside, the cooling air in the part where the stagnation occurs is discharged to the outside from the bypass hole, and the stagnation of the cooling air is caused. A partial temperature rise can be avoided.

[Brief description of drawings]

FIG. 1 is a right side view of a motorcycle equipped with an engine to which the present invention is applied.

FIG. 2 is a cross-sectional view of the engine taken along the line II-II in FIG.

FIG. 3 is a longitudinal sectional view of the engine taken along the line III-III in FIG.

4A and 4B show a first embodiment of the present invention, in which FIG. 4A is a front view of a cylinder block, FIG. 4B is a bottom view of FIG. 4A taken along the arrow 4b, and FIG. -4c Right side view as seen from the arrow.

5A and 5B show a second embodiment of the present invention, in which FIG. 5A is a front view of a cylinder block, FIG. 5B is a bottom view of FIG. 5A taken along the arrow 5b, and FIG. -5c Right side view as seen from the arrow.

FIG. 6 shows a third embodiment of the present invention, (a) is a front view of a cylinder block, (b) is 6b-6b of (a).
The partial sectional view by the arrow, (c) is the partial sectional view by the 6c-6c arrow of (b).

7A and 7B show a modified example of the present invention, in which FIG. 7A is a front view of a cylinder block, FIG. 7B is a bottom view of FIG. 7A taken along arrow 7b, and FIG. 7C is view 7c-7c of FIG. 7B. The right side view by the arrow.

8A and 8B show a conventional technique, in which FIG. 8A is a front view of a cylinder block, FIG. 8B is a bottom view of FIG. 8A taken along arrow 8b, and FIG. 8C is a view of arrow 8c-8c shown in FIG. 8B. Right view from.

[Explanation of symbols]

 2 Engine 4 Cylinder Block 5 Cylinder Head 10 Cylinder Bore 12 Cooling Fins 13, 14 Wall 15 Cap 17 Cooling Air Passage 18 Exhaust Port 32 Blower Means 33 Forced Air Cooling Device 37 Closure 38 Partition Wall 39 Blower Means Attachment 40 40 Outlet 41 Adjustment mouth

Claims (3)

[Claims] 1. An engine provided with a cooling air passage surrounding the outer periphery of a cylinder bore having an exhaust port, a blowing means for introducing cooling air into the cooling air passage, and an outlet for communicating the cooling air passage to the outside. In the forced air cooling device, a closed portion is formed in the cooling air passage on the exhaust port side, and a mounting portion for the blower is provided on one side of the closed portion,
A forced air cooling device for an engine, wherein the discharge port is formed on the other side of the closed portion. 2. Between the blower and the closing part,
2. The forced air cooling device for an engine according to claim 1, wherein an adjusting port for communicating the cooling air passage to the outside is provided, and an opening area of the adjusting port is smaller than an opening area of the discharge port. 3. Bypass holes are provided in the cooling fins provided in multiple stages on the outer periphery of the cylinder bore in the portion where stagnation occurs in the flow of the cooling air in the cooling air passage, and the spaces between the cooling fins are mutually connected. A forced air cooling device for the engine, which is characterized by communicating these spaces with the outside.