JPH08121245A - Supporting structure for crank shaft in internal combustion engine - Google Patents

Abstract

PURPOSE: To sharply reduce bending moment which is generated on a crank shaft, and also form a crank case in a small size. CONSTITUTION: A flange 32 is formed on an outer circumference, and a crank shaft 30 on which a crank pin is pressure fitted to this flange 32 is supported by a plurality of ball bearings 41, 42, 43, and the like. The crank shaft 30 is constituted by a plurality of shaft body 31, and the ball bearing 43 on the output end side of the shaft body 31 is formed as a seal bearing. An oil seal 77 is arranged between a bearing 42 which is formed in the vicinity of this seal bearing 43 and the seal bearing 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft support structure for an internal combustion engine which has a plurality of bearings for supporting a crankshaft having a flange formed on its outer periphery and a crankpin press-fitted into the flange.

[0002]

2. Description of the Related Art FIG. 4 is a side sectional view showing an example of a support structure for a crankshaft of an internal combustion engine used in a conventional snowmobile. In the figure, reference numeral 10 indicates a crankshaft, and the crankshaft 10 is arranged in a crankcase 20. The crankshaft 10 is composed of a plurality of shaft bodies 11, and these shaft bodies 11 are butted concentrically with each other. A flange 12 is formed at the end of each shaft body 11, and a hole 13 is formed in each of the flanges 12. The crank pin 14 is press-fitted into the holes 13 and 13.

A connecting rod 15 is provided between the flanges 12.
Is disposed at one end, and the hole 16 is also formed at this one end. The other end of the connecting rod 15 is connected to a piston (not shown), and this piston reciprocates in the cylinder of the engine. The crank pin 14 is inserted through the hole 16 so that the shaft body 11 rotates at the same speed as each other as the connecting rod 15 reciprocates.

The crankcase 20 has ball bearings 21 and 2.
2 and 23 are arranged and fixed by screws (not shown). Of these, the ball bearing 21 supports the shaft body 11 on the right side in the figure, and the ball bearings 22 and 23 indicate the shaft body 11 on the left side.
I support. The ball bearings 22 and 23 are arranged apart from each other, and a spacer 24 is provided between the ball bearings 22 and 23.
1 penetrates.

The crankcase 2 is provided around the ball bearing 23.
0 Circlip 25 so that the lubricating oil inside does not leak out
Is provided. A left end portion 29 of the left shaft body 11 projects from the left end of the crankcase 20. An oil seal 27 is supported on the crankcase 20 and surrounds the shaft body 11.
The internal lubricating oil is designed not to leak out.

At the left end 29 of the shaft 11 on the left side, V
A belt type automatic transmission is installed. In such a configuration, the engine output is transmitted to the shaft body 11 via the connecting rod 15 and the crankpin 14, and further transmitted from the left end portion 29 to the endless belt type traveling means via the V-belt type automatic transmission. There is. The traveling means of the endless belt is in contact with the snow surface or the ground, and is rotated to propel the snowmobile.

By the way, as described above, the ball bearings 22, 23
Are spaced apart from each other because when the ball bearing 23 is arranged close to the ball bearing 22, the bending that occurs when the left end portion 29 of the shaft body 11 receives the tension of the V belt of the V belt type automatic transmission. This is because when the moment becomes large and the ball bearing 22 is arranged close to the ball bearing 23, the bending moment received by the connecting rod 15 becomes large. In particular, when a bending moment is applied to the shaft body 11 by the tension of the belt, stress concentrates between the right end portion of the shaft body 11 and the crank pin 14 that attempts to restrain the displacement of the shaft body 11, and the crank pin 14 may be broken. In order to prevent this, the crank pin 14 needs to be integrally molded with the flange 12, but in the case of integrally molding, the manufacturing cost increases. Therefore, conventionally, in order to reduce the manufacturing cost, the crank pin 14 is press-fitted into the flange 12 and the ball bearings 22 and 23 are separated from each other in order to reduce the bending moment.

[0008]

However, in the above structure, by disposing the oil seal 27 further on the left side of the ball bearing 23 on the left side, the shaft 11 becomes longer and the bending moment generated there is still large. There was a problem. That is, after all, it does not help much in reducing the bending moment. For the same reason, the crankcase 20 becomes long and large,
Due to the increased weight, performance such as fuel consumption, speed, and horsepower will be reduced.

The present invention has been made in consideration of the above circumstances, and the bending moment generated in the crankshaft can be significantly reduced, and the crankcase of the internal combustion engine can be downsized. It is intended to provide a support structure for the.

[0010]

In order to solve the above problems, the present invention provides a crankshaft support structure for an internal combustion engine in which the crankshaft is supported by a plurality of bearings, and the output end of the crankshaft is provided. It is characterized in that a seal bearing is disposed on the side and an oil seal is disposed between the seal bearing and a bearing near the seal bearing.

[0011]

According to the present invention, since the oil seal is arranged between the bearing in the vicinity of the seal bearing and the seal bearing, it is necessary to lengthen the crankshaft in order to dispose the oil seal and the parts for fixing the oil seal. Absent. Therefore, it is possible to reduce the bending moment generated in the crankshaft due to the force applied to the output end of the crankshaft. For the same reason, it is not necessary to upsize the crankcase. Therefore, the crankcase can be downsized, which can reduce the weight and improve the performance such as fuel consumption, speed, and horsepower.

[0012]

【Example】

A. Configuration of Embodiments An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 is a side sectional view showing an engine E having a crankshaft support structure of an internal combustion engine according to an embodiment, and FIG. 2 is an enlarged view of a part of FIG. 1 showing a main part of the crankshaft support structure. Is. The engine E is a water-cooled 2-cycle parallel 2-cylinder engine, in which a cylinder body 38 is loaded on a crankcase 40. This engine E is
It is installed in a snowmobile.

Reference numeral 30 denotes a crankshaft, which is arranged in a crankcase 40. The crankshaft 30 is composed of four shaft bodies 31, and these shaft bodies 31 are concentrically butted with each other. Of these, the two central shaft bodies 31 are fitted and connected to each other.
A flange 32 is formed at the end of each shaft 31, and a hole 33 is formed in each flange 32. The crank pin 34 is press-fitted into the holes 33, 33.

A connecting rod 35 is provided between the flanges 32.
Is disposed at one end, and the hole 36 is also formed at this one end. The other end of the connecting rod 35 is a piston 37.
The piston 37 reciprocates in the cylinder 39 of the cylinder body 38. The crank pin 34 is inserted through the hole 36, whereby the shaft body 31 is rotated at the same speed as the connecting rod 35 reciprocates.

The crankcase 40 has ball bearings 50, 5
1, 52, 41, 42, 43 are arranged and fixed. Of these, the ball bearings 50 and 51 support the shaft body 31 on the rightmost side in FIG. 1, the ball bearings 52 and 41 support the two intermediate shaft bodies 31 and 31, and the ball bearings 42 and 43 are the left shaft bodies. 31 is supported. The ball bearings 52 and 41 are arranged apart from each other, and a seal 53 is provided between them, and an intermediate shaft body 31 penetrates through the seal 53. In addition, the ball bearings 42, 43
Are spaced apart from each other, a spacer 44 is provided between the two, and the leftmost shaft body 31 penetrates the spacer 44.

The right end of the rightmost shaft 31 is fixed to the flywheel magnet 60 supported by the crankcase 40, and the flywheel magnet 6
0 is fixed to the pulley 61. The pulley 61 is the shaft 3
The rotation of 1 is transmitted to the belt 62, which drives the oil pump 63 and the water pump 64.

On the other hand, the left end portion 4 of the leftmost shaft body 31
A drive-side pulley assembly 66 of the automatic transmission 65 is attached to the gear 9. This drive side pulley assembly 66 is
The support shaft 67 is fixed by inserting the left end portion 49 of the No. 1 unit. A fixed pulley 68 is fixed to the support shaft 67, and a movable pulley 69 that is slidable in the axial direction is attached to the support shaft 67. The movable pulley 69 has a weight 70 with a pin 7
It is rotatably attached by 1. The movable pulley 69 is biased by a spring force (not shown) in a direction away from the fixed pulley. Further, the resistance portion 72 is fixed to the support shaft 67, and the movable pulley 69 is connected to the resistance portion 7.
It is stopped at 2.

A belt 73 is wound around the fixed pulley 68 and the movable pulley 69, and the rotational torque of the crankshaft 30 is transmitted to the endless belt type traveling means 82 (see FIG. 3) described later through the belt 73. It is supposed to be done.
In this automatic transmission 65, when the rotation speed increases, the centrifugal force increases and the weight 70 rotates outward, and the tip of this weight is pushed by the resistance portion 72. As a result, the movable pulley 69 approaches the fixed pulley 68. When the number of rotations decreases, the centrifugal force decreases and the weight 70 rotates inward, and the movable pulley 69 separates from the fixed pulley 68 by the force of the spring (not shown). The facing surfaces of the fixed pulley 68 and the movable pulley 69 are tapered, and the distance between the two faces changes, so that the distance from the axial center of the belt 73 wound around the pulley changes. In this way, it is possible to set the gear ratio according to the rotation speed.

Next, referring to FIG. 2, the crankcase 40
The details of the structure for supporting the leftmost shaft body 31 protruding from will be described. As described above, the ball bearing 42 and the ball bearing 4
3 are spaced apart, and a spacer 44 is provided between them.
Is arranged. The ball bearing 43 arranged on the leftmost side here is a so-called seal bearing, and will be referred to as a seal bearing 4 hereinafter.
Called 3. That is, the packing 74 is attached to both side surfaces so that the lubricating oil in the crankcase 40 does not enter the inside of the seal bearing 43. The internal space of the seal bearing 43 is filled with grease that lubricates internal balls.

Further, a circlip 45 is provided on the outer periphery of the seal bearing 43 so that the lubricating oil inside the crankcase 40 does not leak out. Further, an oil seal 77 is arranged on the outer circumference of the spacer 44 between the ball bearing 42 and the seal bearing 43. In this way, the lubricating oil inside the crankcase 40 is prevented from leaking to the seal bearing 43 side, and in combination with the structure of the seal bearing 43, the lubricating oil is reliably prevented from leaking.

Next, FIG. 3 is a side view showing a snowmobile to which this crankshaft support structure is applied. In this snowmobile, a seat 81 is arranged at a rear portion of a vehicle body 80, and an endless belt type traveling means 82 is provided at a bottom portion. The traveling means 82 is configured by winding a drive belt 85 around a front drive wheel 83 and a rear driven wheel 84. The reference numeral 86 indicates an auxiliary wheel that supports the drive belt 85. Car body 8
0 has a handle 87, and by operating the handle 87, the steering member 88 provided at the bottom of the front portion of the vehicle body 80 can be rotated to change the traveling direction.

The engine E is mounted on the front portion of the body 80 of the snowmobile. The belt 73 wound around the pulley assembly 66 mounted on the shaft 11 is also wound around the relay pulley 89. The rotation is transmitted from the relay pulley 89 to the front drive wheel 83 by the chain 90. In this way, the snowmobile is propelled by transmitting the rotational torque of the shaft 11 to the drive belt 85 of the traveling means.

B. Operation of Embodiment Next, the operation of the snowmobile according to this embodiment will be described. First, the connecting rod 35 reciprocates according to the intake and exhaust strokes of the two cylinders 39 inside the engine E. This reciprocating motion is converted into rotational motion of the shaft body 31 via the crank pin 34. Then, the rotation of the shaft body 31 is transmitted to the oil pump 63 and the water pump 64 by the belt 62 on the right side of FIG. 1, and the oil pump 63 and the water pump 64 are driven.

On the other hand, on the left side of FIG. 1, the rotational torque of the shaft body 31 is transmitted to the belt 73 wound around the drive side pulley assembly 66, and further, the relay pulley 89 shown in FIG.
It is transmitted to the chain 90 and the front drive wheels 83. Then, the drive belt 85 wound around the drive wheel 83 and the driven wheel 84.
Rotates to propel the snowmobile.

When the rotation speed of the shaft body 31 increases,
As described above, the movable pulley 69 approaches the fixed pulley 68, the distance from the axis of the belt 73 increases, and the shaft 3
When the number of rotations of 1 decreases, the movable pulley 69 moves away from the fixed pulley 68, and the distance from the axis of the belt 73 decreases. In this way, the gear ratio, that is, the belt 7
The peripheral speed of 3 becomes appropriate.

Here, the left end portion 49 of the leftmost shaft body 31
Since the tension of the belt 73 is applied to the shaft 31, a moment is generated in the leftmost shaft body 31. However, in this embodiment, by disposing the oil seal 77 between the ball bearing 42 near the seal bearing 43 and the seal bearing 43, the crankshaft is arranged so as to dispose the oil seal and parts for fixing the oil seal. It doesn't have to be long. That is, the distance between the seal bearing 43 and the fixed pulley 68 can be shortened, and the left end portion 49 can be shortened. Therefore, it is possible to reduce the bending moment generated in the shaft body 31 due to the force applied to the left end portion 49 of the shaft body 31. For the same reason, it is not necessary to upsize the crankcase 40. Therefore, it is possible to reduce the weight of the crankcase 40 and improve performance such as fuel consumption, speed, and horsepower.

In the above embodiment, the crankshaft in which the crankpin 34 is press-fitted into the flange 32 is used. However, the present invention is not limited to this, and other types of crankshafts such as a flange and a crankpin are used. It is also possible to apply to what was formed integrally.

[0028]

As described above, according to the present invention, the crankshaft can be shortened, and the bending moment generated therein due to the force applied to the output end of the crankshaft can be reduced. can do. In addition, the crankcase can be downsized, which can reduce the weight and improve performance such as fuel consumption, speed, and horsepower.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an engine E having a crankshaft support structure for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a side cross-sectional view showing an enlarged part of FIG. 1 and showing a main part of a crankshaft support structure of an internal combustion engine according to an embodiment.

FIG. 3 is a side view showing a snowmobile to which the embodiment is applied.

FIG. 4 is a side sectional view showing an example of a conventional crankshaft support structure of an internal combustion engine.

[Explanation of symbols]

E engine, 30 crank shaft, 31 shaft body, 32 flange, 33 hole, 34 crank pin, 35 connecting rod, 36 hole, 37 piston, 38 cylinder body, 39 cylinder, 40 crank case, 41,
42,50,51,52 Ball bearing 43 Ball bearing (seal bearing), 44 Spacer, 49
Left end (output end) 65 Automatic transmission, 66 Drive side pulley assembly, 67
Support shaft, 68 fixed pulley, 69 movable pulley, 70
Weight, 73 belt, 74 packing, 77 oil seal.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location // B62M 27/02 J

Claims (1)

[Claims] 1. A crankshaft support structure for an internal combustion engine, wherein a crankshaft is supported by a plurality of bearings, wherein a seal bearing is disposed on an output end side of the crankshaft, and a bearing near the seal bearing is provided. A crankshaft support structure for an internal combustion engine, wherein an oil seal is provided between the seal bearing and the seal bearing.