JPH0648082Y2 - Axial play removal device for camshaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an axial play removing device for a camshaft of an engine.

[Conventional technology]

In a 4-cycle engine, a camshaft axially supported in a crankcase or a rocker arm chamber is rotationally driven at a speed half that of the crankshaft, and a cam formed on the camshaft opens and closes an intake / exhaust valve (open / close timing). Angle) is controlled.

The camshaft is rotationally driven by gear meshing with the crankshaft in an overhead valve (OHV) engine or a side valve engine, and by a chain / sprocket transmission mechanism between the camshaft and the crankshaft in an overhead camshaft (OHC) engine. It

In this case, cast iron or steel is generally used as the material of the camshaft, but the crankcase or rocker arm chamber supporting the camshaft is generally made of aluminum alloy (in consideration of weight saving and heat dissipation). It is often made from aluminum die casting.

Japanese Utility Model Publication No. 57-52323 is a document showing a conventional shaft support structure of this type of camshaft.

[Technical issues to be solved by the invention]

By the way, when the camshaft is made of iron and the case side that supports it is made of aluminum alloy, if the temperature rises during engine operation, the clearance in the axial direction of the camshaft ( Thrust play)
May increase, the camshaft may move in the axial direction, and a tapping sound may be generated from the shaft end (bearing) of the camshaft.

Further, in order to reduce the gear noise, the crank gear and the cam gear may be helical gears. In this case, axial thrust is generated in the camshaft, and the possibility of the tapping sound is increased.

Therefore, as a method of preventing the generation of these hammering sounds, conventionally, a method of preparing several kinds of shims having different thicknesses and inserting the shims into the shaft end of the camshaft has been adopted. However, with this method, the shim must be selectively fitted for each engine, which requires a large number of assembly steps and it is difficult to sufficiently remove the play in the thrust direction.

Further, since the insertion of the shim is carried out at room temperature, if the temperature becomes high during engine operation, there is a tendency for play due to a difference in linear expansion with the case side (aluminum alloy), resulting in a reduction in the hammering effect.

The present invention has been made in view of the above-mentioned conventional technical problems, and an object of the present invention is to prevent rattling noise by eliminating rattling in the axial direction of the camshaft and to prevent the camshaft from moving in the axial direction due to temperature rise. It is an object of the present invention to provide an axial play removing device for a camshaft which can absorb a change in clearance and can reduce the rotational frictional force of the camshaft to prevent heat generation and output reduction due to friction.

[Means for solving problems]

According to a first aspect of the present invention, in an axial play removing device for a camshaft of an engine, the camshaft is fitted into a bearing hole on an inner surface of an engine crankcase, and a ball is provided between the camshaft shaft end surface and an end wall surface of the bearing hole. Further, the above-mentioned object is achieved by adopting a constitution in which the axial pressing means by the spring is provided.

According to a second aspect of the present invention, in the axial play removing device for a camshaft of an engine, a bearing hole of the camshaft is formed on an inner surface of an engine crankcase, a female screw is formed on a wall portion of the bearing hole, and the female screw is adjusted. By further tightening the bolt so that the axial position can be adjusted, and by providing an axial pressing means by a ball and a spring between the axial end surface of the cam shaft fitted in the bearing hole and the end surface of the adjusting bolt, The above object is efficiently achieved.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a longitudinal sectional view showing an axial play removing device for a camshaft according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG.

In FIGS. 1 and 2, a crankcase 1 is constructed by assembling a case body 1A and a case cover 1B, and a crankshaft 2 and a camshaft 3 are rotatably provided in the crankcase with a predetermined axial distance. It is pivotally supported.

The illustrated engine is a side valve engine, and a cylinder part 4 and an intake / exhaust port part 5 are formed integrally with the crankcase 1 (main body 1A), and a cylinder head 6 is fixed to the top surface thereof.

A piston 8 is fitted into a cylinder bore 7 formed in the cylinder portion 4, and the piston 8 is connected to a crank pin of the crankshaft 2 via a connecting rod 9.

A combustion chamber 10 is formed on the lower surface (inner surface) of the cylinder head 6. The combustion chamber 10 is compressed and expanded by the stroke of the piston 8, and the opening and closing of the combustion chamber 10 is controlled by intake and exhaust valves 11, 11.

A cam gear 13 that meshes with a gear (crank gear) 12 of the crankshaft 2 is formed on the camshaft 3, and the camshaft 3 is driven at a rotational speed that is ½ of the crankshaft via the gears 12 and 13. To be done.

The camshaft 3 is provided with intake and exhaust cams 14 and 15, and the displacement of the cams 14 and 15 is controlled between the cams 14 and 15 and the intake and exhaust valves 11 and 11, respectively. Tappets 16, 16 are provided for transmission to the.

As shown in FIG. 1, one end (left end) of the camshaft 3 projects to the outside of the crankcase 1, while the other end (right end) thereof has a bearing hole 17 formed on the inner surface of the crankcase 1.
It is fitted and supported by.

The protruding side (left side) of the camshaft 3 is pivotally supported by a ball bearing 18 mounted on the crankcase 1 as shown.

In the above structure, the right shaft end surface 19 of the camshaft 3
Axial pressing means utilizing the elastic force of the spring 20 is pressed against.

In the illustrated example, a ball (steel ball) 21 is seated in a recessed hole formed in the center of the end surface of the camshaft 3, and a compression coil spring 20 mounted between the ball 21 and the end wall surface of the bearing hole 17 is provided.
The camshaft 3 is biased to the left by the.

In this way, by pressing the camshaft 3 in the axial direction by the elastic force of the spring 20, axial backlash (play) in a normal operating state is removed, and a rattling sound such as a rattling sound is not generated. .

Further, even if the axial clearance increases due to the difference in linear expansion between the camshaft 3 and the flank case 1 when the temperature rises during engine operation, it can be easily absorbed by the displacement of the spring 20.

According to the axial play removing device for the camshaft 3 shown in FIGS. 1 and 2, the structure is simple and the assembling is easy, and the axial play of the camshaft 3 is surely removed even when the engine temperature rises. It became possible to do.

Further, the axial pressing means by the ball 21 and the spring 20 is provided between the camshaft shaft end surface 19 and the end wall surface of the bearing hole 17, so that between the fixed bearing hole 17 and the rotating camshaft 3 end surface 19. Even in this case, the rotational frictional force of the camshaft 3 can be reduced, and heat generation and output reduction due to friction can be prevented.

FIG. 3 is a vertical sectional view of an axial play removing device for a camshaft according to a second embodiment of the present invention.

In FIG. 3, a female screw is formed on a wall portion inside the bearing hole 17 of the crankcase 1, and an adjusting bolt 25 is screwed into the female screw so as to adjust the position in the axial direction.

The adjusting bolt 25 is for adjusting the spring force of the compression coil spring 20 mounted between the ball 21 and the ball 21, and is fixed at the adjusting position by the lock nut 26.

The second embodiment of FIG. 3 is different from the embodiments of FIGS. 1 and 2 in the points described above, but the other parts have the same structure, and the corresponding parts have the same numbers. , And the detailed description thereof is omitted.

According to the embodiment of FIG. 3, the axial play of the camshaft 3 can be removed easily and accurately as in the embodiment of FIGS. 1 and 2, and the elastic force of the spring 20 of the axial pressing means can be eliminated. Thus, the axial play removing means of the camshaft can be obtained, which can easily adjust and the elastic force can be accurately applied.

Therefore, according to the second embodiment of FIG. 3, in addition to the effect of the first embodiment of FIGS. 1 and 2, the axial thrust of the camshaft 3 can be adjusted, which results in rattling noise. By adjusting the thrust to the minimum within the range of the purpose of prevention, it is possible to reduce the friction and heat generation of the thrust bearing part to the minimum, and further adjust the thrust at the time of engine shipping inspection. The effect that can be obtained is also obtained.

[Effect of device]

As is clear from the above description, according to the invention of claim 1, in the axial play removing device of the camshaft of the engine, the camshaft is fitted in the bearing hole of the inner surface of the engine crankcase, and the camshaft shaft end surface and Since the axial pressing means by balls and springs is provided between the end wall surface of the bearing hole and the axial backlash of the camshaft, the tapping noise is prevented and the axial clearance of the camshaft due to temperature rise is prevented. There is provided an axial play removing device for a camshaft, which can absorb the change in the camshaft and can reduce the rotational frictional force of the camshaft to prevent heat generation and output reduction due to friction.

According to the invention of claim 2, in the axial play removing device for the camshaft of the engine, the bearing hole of the camshaft is formed on the inner surface of the engine crankcase, the female screw is formed on the wall portion inside the bearing hole, and the female screw is formed. Since the adjusting bolt is fastened in such a manner that the axial position can be adjusted, and the axial pressing means by the ball and the spring is provided between the axial end surface of the cam shaft fitted in the bearing hole and the end surface of the adjusting bolt. It is possible to eliminate the rattling noise by eliminating the play in the axial direction of the camshaft and absorb the change in the axial clearance of the camshaft due to the temperature rise.
The rotational frictional force of the camshaft can be reduced to prevent heat generation and output reduction due to friction, and the axial thrust of the camshaft can be adjusted. There is provided an axial play elimination device for a camshaft, which can adjust the thrust to a minimum to reduce the friction and heat generation of the thrust bearing portion to a minimum, and can also adjust the thrust at the time of engine shipping inspection.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an engine showing an axial play removing device for a camshaft according to an embodiment of the present invention, and FIG.
FIG. 3 is a sectional view taken along line II-II in the figure, and FIG. 3 is a longitudinal sectional view of an engine showing a camshaft axial play removing device according to another embodiment of the present invention. 1 …… Crank case, 3 …… Cam shaft, 17 …… Bearing hole, 20 …… Spring, 21 …… Ball, 25 …… Adjusting bolt, 26 …… Lock nut.

Front Page Continuation (56) References Micro Application (JP, U) Micro Application (JP, U) of the specification and drawings attached to the application of Sho 60-172292 (Actual Development Sho 62-79907) Microfilm (JP, U) of the detailed description and drawings attached to the application for Sho 56-161661 (Shokai Sho 58-65429)

Claims (2)

[Scope of utility model registration request] 1. A camshaft axial play removing device for an engine, wherein the camshaft is fitted into a bearing hole in an inner surface of an engine crankcase, and a ball and a spring are provided between the camshaft shaft end surface and an end wall surface of the bearing hole. An axial play removing device for a camshaft, characterized in that the axial pressing means is provided. 2. A device for removing axial play of a camshaft of an engine, wherein a bearing hole of the camshaft is formed on an inner surface of an engine crankcase, a female screw is formed on a wall portion of the bearing hole, and an adjusting bolt is provided on the female screw. A shaft of a cam shaft, which is fastened so as to be adjustable in axial position, and axially pressing means by a ball and a spring is provided between the shaft end face of the cam shaft fitted in the bearing hole and the end face of the adjusting bolt. Directional play removal device.