JPS6231716A - Bearing device of crank shaft - Google Patents

Abstract

PURPOSE:To reduce looseness between a crank shaft and bearing holes by applying pre-load to outer races of ball bearings by energizing the outer races in the axial direction by means of an energizing member. CONSTITUTION:Outer races 44a, 45a are supplied with axial directional pre-load by means of coned. disc springs 49, 50. As the result, outer races 44a, 45a of right and left ball bearings 44, 45 are respectively deviated a little to crank chambers 10, 11, and existing clearances between respectively inner races 44b, 54b and outer races 44a, 45a, and respective balls 44c, 45c are made narrower. Then, the clearances between respective outer races 44a, 45a and bearing holes 41, 42 die offset and looseness toward the crank shaft 21 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bearing device for a crankshaft used in a multi-cylinder two-stroke internal combustion engine.

(Prior Art) A crankshaft of a multi-cylinder two-stroke internal combustion engine is rotatably supported by both side walls of a crankcase and a partition wall defining a crank chamber via a bearing device.

In this bearing device, an inner race of a ball bearing is press-fitted and fixed into a journal portion of a crankshaft, and an outer race is supported by fitting into bearing holes in both side walls and a partition wall of a crankcase.

By the way, due to the fitting tolerance between the bearing hole and the 7th outer race, manufacturing errors, etc., some play may occur in the journal part of the crankshaft, and this may cause operational noise and vibration. .

For this reason, as disclosed in Japanese Utility Model Application Publication No. 58-16421, in a single-cylinder internal combustion engine, an axial preload is applied to the outer race of the ball bearing on both side walls of the crankcase, so that the balls of the ball bearing and the outer race of the ball bearing are There is also a method that eliminates the generation of impact noise and vibration by reducing the existing gap formed between the inner races and reducing the play between the journal portion of the crankshaft and the bearing hole.

(Problems to be Solved by the Invention) Incidentally, in a multi-cylinder two-stroke internal combustion engine, there is no means for applying axial preload to the ball bearings on the partition wall that defines the crank chamber of each cylinder, and the The play that occurs between the bearing hole and the journal portion of the crankshaft is one of the causes of impact noise and vibration.

This invention was made in view of the above circumstances, and is a multi-cylinder 2-stroke that can reduce impact noise and vibration by applying preload to the outer race of the ball bearing in the partition wall that defines the crank chamber with a simple structure. The present invention relates to a crank bearing device for an internal combustion engine.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a pair of ball bearings in a partition wall defining a crank chamber of a crankcase of a multi-cylinder two-stroke internal combustion engine. In the crankshaft bearing device, the inner race of the ball bearing is fixed to the journal portion of the crankshaft, and the outer race is fitted to the bearing hole of the partition wall, A biasing member made of an external material is interposed between the sealing member and the ball bearings disposed on both sides of the sealing member, and the biasing member uses the sealing member as a stopper to push the ball bearing 7. The feature is that the outer race is biased in the axial direction.

(Function) In the present invention, the biasing members interposed between the sealing member fitted to the partition wall defining the crank chamber and the ball bearings disposed on both sides of the sealing member act as stoppers. Forces the outer race of the ball bearing in the axial direction.

As a result, an axial preload is applied to the 7th outer race of the ball bearing, the existing gap formed between the ball of the ball bearing and the 7th outer race and the inner race is reduced, and the play between the journal part of the crankshaft and the bearing hole is reduced. This reduces the occurrence of impact noise and vibration.

(Example) Hereinafter, an example in which the present invention is applied to an internal combustion engine of a motorcycle will be described in detail based on the accompanying drawings.

In FIG. 1, reference numeral 1 indicates a vehicle body frame, and a front wheel 2 is attached to this vehicle body frame 1 via a front suspension.
Further, rear wheels 3 are respectively provided via rear sub-sensions. A five-engine internal combustion engine 4 is mounted on the vehicle body frame 1, and as shown in FIG. 2, a two-cylinder, two-stroke internal combustion engine 4 is used.

A crankcase 5 of this internal combustion engine 4 is formed by integrally joining an upper case 6 and a lower case 7. A crank chamber 10.11 is formed within the crankcase 5 by partition walls 8 and 9 of an upper case 6 and a lower case 7, and a cylinder block 12 is placed on the upper case 6.

Cylinder 13.14 is formed in this cylinder block 12, and each cylinder 13.14 communicates with the crankcase to, it via a transfer passage 15.16. A piston 17.18 is arranged in the cylinder 13.14 so as to be movable up and down, and this piston 17.18 is connected to a crank pin 22.23 of the crankshaft 21 via a connecting rod 19.20.

A flywheel magnet 24 is fixed to one end of the crankshaft 21, and a crank gear 25 is fixed to the other end, and the crank gear 25 is connected to the clutch gear 2 of the main shaft 26.
It is meshed with 7.

The upper case 6 and the lower case 7 each have a bearing hole 28.
A journal portion 32.33 of the crankshaft 21 is rotatably supported in the bearing holes 28 and 29 via ball bearings 30.31.

The outer race 30a of the crank gear side ball bearing 30 is fitted into the bearing hole 28, 29, and the circlip 3
4 restricts movement in the axial direction. The inner race 30b is press-fitted into the journal portion 32 and fixed thereto.

Further, the inner race 30b is fixedly supported by the crank gear 25 via a collar 35, and the space between the collar 35 and the bearing hole 28 is sealed with an oil seal 36.

The ball bearing 31 on the flywheel magneto 24 side is
The outer race 31a is fitted into the bearing holes 28 and 29, and is prevented from rotating by a pin 37. inner lace 3
1b is press-fitted into the journal portion 33 and fixed.

A plate 38 is interposed between the ball bearing 31 and the side wall of the bearing hole 28.29, and a disc spring 39 serving as a biasing member is provided between the plate 38 and the outer race 31a. Forced in the axial direction. There is an oil seal 40 between the journal part 33 and the crankcase 5.
is sealed.

- A sealing member 43 is interposed in the bearing holes 41.42 formed in the partition walls 8, 9 of the side case 6 and the lower case 7, and ball bearings 44.45 are disposed on both sides of the sealing member 43.
are interposed, and the seven outer races 44a and 45a of each ball bearing 44.45 are fitted into the bearing hole 41.42,
Rotation is prevented by pins 46 and 47, respectively.

In addition, the inner races 44b and 45b are connected to the journal portion 48.
is press-fitted into the

Disc springs 49 and 50, which are urging members, are provided between the seal member 43 and the respective ball bearings 44 and 45, and the seal member 43 acts as a stator/bar.
'The outer races 44a and 45a are biased in opposite axial directions to apply preload.

Next, the operation of this embodiment will be explained.

The inner races 44b, 45b of the ball bearings 44, 45 provided on the partition walls 8, 9 defining the crank chamber 10, 11 in the crankcase 5 are fixed to the journal portion 48 of the crankshaft 21 by press fitting, Axial movement is restricted.

On the other hand, the outer races 44a, 45a are fitted into the bearing holes 41.42 of the partition walls 8, 9, and this fitting portion is determined by the fitting tolerance between the outer races 44a, 45a and the bearing holes 41.42, and the manufacturing of these. Depending on the tolerance etc., the outer race 44
A gap may be formed between the outer circumferential surface of a, 45a and the bearing surface of the bearing hole 41.42.

This may cause some play in the crankshaft 21 and cause impact noise and vibration noise during engine operation, but this may cause the outer races 44a and 45a of the ball bearings 44 and 45 to move in the axial direction. An axial preload is applied by disc springs 49 and 50 that use the seal member 43 as a stopper.

As a result, the outer races 44a, 45a of the left and right ball bearings 44.45 are slightly deviated toward the crank chamber 10.11, respectively, and the inner and outer races 44a, 45a,
The existing gaps between the balls 44b, 45b and the balls 44c, 45C are narrowed, which offsets the gaps between the outer races 44a, 45a and the bearing holes 41, 42, thereby reducing the play of the crankshaft 21.

At this time, the disc springs 49 and 50 are arranged on both sides of the seal member 43, and the outer races 44a of the ball bearings 44 and 45 are arranged on both sides of the seal member 43.
, 45a in opposite axial directions.

Therefore, the load applied to the sealing member 43 by the disc springs 49 and 50 is offset, and the sealing member 43 acts as a stopper for the disc springs 49 and 50, thereby applying an equal preload.

Further, the ball bearing 31 on the side of the flywheel magnet 24 uses the plate 38 as a stopper and uses the skin spring 39 to urge the seventh outer race 3La toward the crank chamber 11 side to apply preload. The reaction force of the preload of the disc spring 39 is applied to the outer race 30a of the ball bearing 30 via the circlip 34 on the other crank gear 25 side, thereby applying axial preload to this as well. As a result, the seven outer races 30a, 31a of the ball bearings 30, 31 on both sides are slightly deviated inward, and the inner and outer races 30a,
The existing gap between 31a and balls 30c and 31c is narrowed. This offsets the gap between the outer races 30a, 31a and the bearing holes 28, 29, thereby reducing the play of the crankshaft 21.

The ball bearing 30 on the crank gear 25 side is preloaded by a thrust force exerted by the helical gear in a direction to move the crankshaft 21 in the axial direction.

In this way, the play of the crankshaft 21 as a whole can be reduced as much as possible, and the impact noise and rotational vibration of the crankshaft 21 due to the play when the engine explodes fuel can be reduced.

Further, the ball bearings 44.45 provided in the partition walls 8, 9 of the crank chamber 10.11 are preloaded by disk springs 49, 50 using the existing seal member 43 as a stopper to apply preload to the respective seven outer races 44a, 45a. Therefore, there are fewer parts for applying preload, and the structure is simple, compact, and easy to assemble, and it can be added to other internal combustion engines with simple changes.

Furthermore, when assembling the crankcase 5 and the crankshaft 21, the disc spring 49.50 that provides preload between the crank chambers to and tt is connected to the sealing member 43 and the ball bearing 44.4.
It is incorporated between 5 and 5.

Furthermore, the upper case 6 and the lower case 7 can be assembled by simply pressing the disc spring 39 in the axial direction with a jig through the oil seal 40 on the flywheel magnet 24 side and the plate 38. can.

(Effects of the Invention) As described above, the present invention provides an elastic member between the seal member fitted to the partition wall defining the crank chamber of a multi-cylinder internal combustion engine and the ball bearings disposed on both sides of the seal member. Since a biasing member consisting of 7 outer races of the ball bearings on the partition wall defining the crank chamber is biased in the axial direction by this biasing member, the existing 7 outer races of the ball bearings on the partition wall defining the crank chamber Preload can be applied with a simple structure using the above members, and by reducing the play between the crankshaft and the bearing hole, it is possible to eliminate impact noise and vibration.

[Brief explanation of the drawing]

Figure 1 is a side view of a motorcycle to which this invention is applied;
The figure is a sectional view taken along the line ■-■ in FIG. 5...Crank case 6...Upper case 7...Lower case 8.9...Dividing wall 21...Crankshaft 30.31.44.45...Ball bearing 28.29,
41.42... Bearing hole 39.49.50... Belleville spring

Claims (1)

[Claims] A pair of ball bearings is fitted into a partition wall defining a crank chamber of a crankcase of a multi-cylinder two-stroke internal combustion engine with a seal member interposed between them, and the inner race of this ball bearing is connected to the journal of the crankshaft. In a crankshaft bearing device whose outer race is fitted into a bearing hole of the partition wall, an elastic member is provided between the seal member and the ball bearings disposed on both sides of the seal member. A crankshaft bearing device in which a biasing member consisting of the following is interposed, and the biasing members bias the outer race of the ball bearing in the axial direction using the seal member as a stopper.