JPS60179597A - Holding structure of crankshaft for internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a crankshaft holding structure that absorbs vibrations in the thrust direction of a crankshaft in an internal combustion engine.

(Prior Art) Conventionally, in a system in which a crankshaft is held in a crankcase via a rolling bearing, the inner ring of the rolling bearing is press-fitted onto the crankshaft, and the outer ring is press-fitted into the crankcase. In this case, if the machining and assembly accuracy of the crankshaft and crankcase decreases, problems arise in that vibrations of the crankshaft in the thrust direction increase, vibration and noise of the two engines increase, and durability decreases. Therefore, the machining and assembly precision of these cranks ili+l+ and crankcases must be extremely high, making it difficult to improve productivity and yield. Particularly when using a press-fit assembly type crankshaft, in which the crank web and crank pin are partially press-fitted, or when using a 9-part type crankcase, the accuracy of bearing position may be affected because errors in each part overlap. Improving it becomes even more difficult.

(Object of the Invention) The present invention was made in view of the above circumstances, and is capable of absorbing vibrations in the thrust direction of the crank 11q port to reduce engine vibration and noise and improve durability. An object of the present invention is to provide a crankshaft holding structure for an internal combustion engine that can improve productivity and yield by lowering the machining and assembly precision of the shaft and crankcase.

(Structure of the Invention) In order to achieve this object, the present invention interposes an elastic material between the mutually opposing thrust bearing surfaces of the outer ring of the rolling bearing and the crankcase. That is, the present invention relates to an internal combustion engine in which a crankshaft is held in a crankcase via a rolling bearing.

An elastic material is interposed between the thrust bearing surface of the outer ring of the rolling bearing and the thrust bearing surface of the crankcase that faces the thrust bearing surface of the outer ring.

(Example) The present invention will be described in detail below based on the drawings.

FIG. 1 is a side sectional view of a forced air-cooled four-stroke engine which is an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-■,
FIG. 3 is an enlarged sectional view of the holding portion of the crank bearing.

In these figures, reference numeral 10 denotes a press-fit assembly type crankshaft, in which crank bins 14 are press-fitted into a pair of left and right crank webs 12, 12, and are integrally assembled. The crankshaft 10 is held in a left-right split crankcase 20 (20a, 20b) via a pair of left and right ball bearings 16,18. A sprocket 22. One-way clutch for starting 24. ■The drive pulley 26 of the belt transmission device is attached. A magneto generator 28 is attached to the right protrusion of the crankshaft 10.

30 is a cylinder, 32 is a cylinder sleeve, 34 is a cylinder head, 36 is a piston, 38 is a connecting rod, 40
is a spark plug. A camshaft 42 is attached to the cylinder head 34, and a timing chain 46 is wound around the sprocket 44 fixed to the camshaft 42 and the sprocket 22 of the crankshaft 10. As a result, the camshaft 42 rotates at half the speed of the crankshaft 10.

Reference numerals 48 and 50 denote an intake valve and an exhaust valve, which are driven to open and close by the camshaft 42 via rocker arms 52 and 54.

56 is a cover 9 from the outside of the generator 28;

Cylinder 30. It is made to cover the cylinder head 34. An opening 60 is formed in this cover 56 and faces a fan 58 fixed to the generator 28.
When the cylinder 30.8 rotates together with the crankshaft 10, outside air is sucked into the cover 56 through the opening 60 and the cylinder 30.8 rotates together with the crankshaft 10. The cylinder head 34 is forcibly cooled.

62 is a balance shaft, and the crank web 12°12
A balance weight 64 interposed therebetween is integrally formed. This balance weight 64 includes a gear 66 fixed to the crankshaft 10 and a gear 68 fixed to the balance shaft 62.
As a result, it is rotated in the opposite direction at the same speed as the crankshaft 10. As a result, the balance weight 64 cancels the -order vibrations caused by the rotation of the crankshaft 10 and the vertical movement of the piston 36, and the vibrations of the engine are reduced. Note that oil passages 70 and 72 are formed in this balance shaft 62, and one oil passage 7
0.72 is communicated via a centrifugal filter 74.

Further, the balance shaft 62 is formed with a nozzle arrow pointing toward the crank pin 14 from between the crank webs 12 . Therefore, the lubricating oil that is pumped from the lubricating oil pump (not shown) to the T oil passage 70 via the pipe 78 enters the oil passage 72 after metal powder and the like are separated by the centrifugal filter 74.
Some of it is ejected from the spout Aro. This ejected lubricating oil periodically adheres to the large end of the connecting rod 38 and lubricates this large end.

The bearing 18 of the crankshaft 10 is held in the crankcase 20b as shown in FIG. 3. That is, the inner ring 18a of the bearing 18 is press-fitted onto the crankshaft 10, and the outer ring 18b of the bearing 18 is fitted into a steel insert 80 cast into the crankshaft 7kl'r-su20b. The thrust receiving surface 82 of this outer ring 18b is connected to the outer rank case 20.
9 thrust receiving surfaces 82.b facing the thrust receiving surfaces 84 of .
Between the rings 84 and 84, a ring 8 on which a rubber elastic material 86 is baked.
8 is being held.

1. Between the thrust bearing surface of the outer shaft 16b of the bearing 16 of the crankshaft 10 and the thrust bearing surface on the crankcase 20a side. A ring 88 on which a rubber elastic material 86 similar to that shown in FIG. 3 is baked is held.

As a result, the play in the thrust direction of the crankshaft 10 is absorbed by the elastic material 86.86 baked into the rings 88.88. That is, the crank web 12 of the crankshaft 10
．． 12 and crank pin 14 due to the sum of machining tolerances or thermal deformation.

Even if the positional error of the bearings 16, 18 becomes large, even if there is a machining error or thermal deformation of the crankcase 20, the deformation of the elastic members 86 and 86 will absorb the error to a considerable extent and ensure that the crankshaft 10 is properly adjusted. can be held in place. Further, vibrations of the crankshaft 10 in the thrust direction can also be absorbed by the elastic phases 86, 86.

In this embodiment, a ring 88 having an elastic phase 86 is attached to the holding portions of the two bearings 16 and 18, but even if this ring 88 is attached only to one of the bearings 16 or 18, the intended effect of the present invention can still be achieved. The purpose can be achieved. In addition, in this embodiment, the sintered material is fixed to the ring 88 of the elastic material 86, so that it is easy to assemble and the handling of one part is easy. However, in the present invention, an independent elastic material may be used. Of course. If rubber is used as the elastic material as in the embodiment, there is an advantage that the damping performance of rubber itself can be effectively utilized, but as the elastic material, 4A materials other than rubber can be used.

For example, a spring washer bent into a wave shape, a washer which has a spring action by twisting a large number of teeth provided on the inner and outer peripheries, etc. can also be used. Furthermore, the present invention can be applied not only to single-cylinder engines but also to multi-cylinder engines.

(Effects of the Invention) As described above, the present invention interposes an elastic material between the mutually opposing thrust bearing surfaces of the outer ring of the rolling bearing that supports the crankshaft and the crankcase, so that the Even if the crankshaft bearing spacing changes due to machining/assembly errors or thermal deformation, the variation is absorbed by the elasticity of the elastic material, and the play in the thrust direction of the crankshaft does not become excessive. Therefore, vibrations of the crankshaft in the thrust direction are absorbed by this elastic material, suppressing noise and improving durability. On the other hand, since it is possible to lower the machining and assembly accuracy of the crankshaft and crankcase, productivity can be improved and yields can be increased.

[Brief explanation of the drawing]

FIG. 1 is a side view of one embodiment of the present invention, and FIG. 2 is a side view of an embodiment of the present invention.
The U-line sectional view and FIG. 3 are enlarged sectional views of the holding portion of the crank bearing. 10...Crankshaft, 16.18...Bearing. 16b, 18b ・Outer ring, 20 ・Crankcase 82
．． 84... Thrust receiving surface, 86... Elastic phase. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Yama 1) Yu Fumi Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In an internal combustion engine in which the crankshaft is held in the crankcase via a rolling bearing, an elastic material is provided between the thrust bearing surface of the outer ring of the rolling bearing and the thrust bearing surface of the crankcase that faces the thrust bearing surface of the outer ring. What is claimed is: 1. A crankshaft holding structure for an internal combustion engine, characterized in that: