JPH0842311A - Direct acting valve system in internal combustion engine - Google Patents

Abstract

PURPOSE:To lighten and miniaturize the valve system of an internal combustion engine by storing the upper end part of the shaft part of an engine valve in a guide cylinder, and slidably fitting a cam receiving plate which is in contact with a rotating cam and abuts on an inner shim, to the guide cylinder. CONSTITUTION:An approximately discoidal cam receiving plate 10 is vertically slidably fitted to and inserted in a bore 5a of the upper part of a guide cylinder 5 integrated with a cylinder head. The dimension of an area where the cam receiving plate 10 is fitted in the guide cylinder 5, is made to occupy approximately the same as the lift quantity of an engine valve 1 or a little bit larger than it, and the plate thickness of the cam receiving plate 10 is made to have a little bit larger than the lift quantity. By this construction, when large offset load acts on the cam receiving plate 10 during a pressing period by a rotating cam 9, the tilting of the cam receiving plate 10 becomes little so that the cam receiving plate 10 can slide in the bore 5a of the guide cylinder 5. Further, the weight and vertical dimension of the cam receiving plate 10 can be suppressed to their minimum extent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct-acting type valve operating device for an internal combustion engine, and more particularly to a valve operating device designed to be compact and lightweight.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional direct-acting type valve operating system mainly used in a DOHC engine, in which an annular groove ( 02)
Of a pair of cotters (03) and (03) fitted to each other, a spring retainer (04) fixed by both cotters (03), and a guide tube (05) integrated with a cylinder head (not shown) The valve spring (06) compressed between the bottom surface and the lower surface of the spring retainer (04) and the upper end of the engine valve (01) are covered from above, and the bore (05a) of the guide cylinder (05) is covered. ) Consists of a tappet (07) which is slidably fitted in the inside of the bracket.

The shaft end of the engine valve (01) has a tappet (0
It abuts on the center of the lower surface of the top wall (07a) of 7), and is attached to the upper surface of the shim (08) for valve clearance adjustment fitted in the disc-shaped recessed hole (07b) on the upper surface of the top wall (07a). Is in contact with the rotating cam (09).

In such a direct acting type valve operating device, since the number of parts of the valve operating system is relatively small and the rotary cam (09) is located directly above the valve body, the allowable rotational speed of the engine is reduced. There is an advantage that the output performance can be improved.

By the way, it is the weight of the valve train that is the most obstacle in increasing the allowable engine speed. The larger the weight, the larger the inertial weight, and the followability of the valve body to the rotating cam. Is deteriorated, the efficiency of intake and exhaust is deteriorated, and the output is lowered.

Therefore, these days, the tappet (07) and the spring retainer (04) are made of an iron alloy instead of the conventional iron, or the engine valve (01) is made of a titanium alloy or ceramics to operate the valve operating valve. Attempts have been made to make the system even lighter.

However, there are almost no examples in which the structure of the valve operating system, in particular, the shape of the tappet body has been changed to try to reduce the weight, and the tappet (07) for this type of valve operating system is more consistent than before. Then, it is generally formed in a cylindrical body having an upper surface closed.

[0008]

The tappet as described above
Since (07) has a relatively long cylindrical body (07c), its weight reduction is limited.

Further, when the body portion (07c) is provided, the axial dimension of the guide cylinder (05) of the cylinder head into which it is fitted is inevitably large. As a result, the vertical dimensions of the guide cylinder (05) and cylinder head, the overall length of the engine valve (01), and the overall vertical dimension of the valve operating system become large, and the height of the engine alone also increases accordingly. To be larger,
The degree of freedom in body design is limited.

The present invention has been made to solve the above problems, and by changing the shape of the tappet,
An object of the present invention is to provide a direct-acting type valve operating device for an internal combustion engine, which is capable of reducing the weight and size of the valve operating system.

[0011]

According to the present invention, the above problems can be solved as follows. (1) The upper end of the shaft portion of the engine valve, which is assembled in the cylinder head with the cotter, the spring retainer, and the valve spring constantly urged upward, is housed in the guide cylinder that is integral with the cylinder head. In the guide cylinder, a cam receiving plate having a required thickness, the upper surface of which contacts the rotating cam and the center of the lower surface of which contacts the inner shim fitted to the shaft end of the engine valve, is slidably fitted vertically. To meet.

(2) In the above item (1), the cam receiving plate and the inner shim are in spherical contact.

(3) In the above item (1), a spherical body is rotatably fitted into a concave hole provided at the center of the lower surface of the cam receiving plate,
The lower surface of this sphere is brought into close contact with the upper surface of the inner shim.

(4) In the above item (1), the cam receiving plate is made of a light metal material, and a hard shim is provided in the center of the lower face in a concave hole provided in the upper face of the cam receiving plate that contacts the rotating cam. Hard chips are fitted into the recessed holes.

[0015]

The engine valve is driven by the rotating cam pressing the inner shim fitted to the shaft end of the engine valve and the cam receiving plate brought into contact with the inner shim. The need for a small-sized cylindrical body is eliminated, and the valve train can be made lightweight and compact. Further, since the inner shim is interposed between the engine valve and the cam receiving plate, sliding wear of the shaft end of the engine valve is prevented.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the same members as those of the conventional example shown in FIG. 6 are denoted by reference numerals obtained by removing the leading “0” from the reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a first embodiment of the present invention, in which a hard metal material such as chrome steel or gray cast iron is provided in the upper bore (5a) of the guide cylinder (5) which is integral with the cylinder head. A substantially disk-shaped cam receiving plate (10) is inserted so as to be slidable up and down.

The size of the area of the cam receiving plate (10) fitted in the guide tube (5) is set to be approximately equal to or slightly larger than the lift amount of the engine valve (1).
The thickness of the cam receiving plate (10) is preferably slightly larger than the lift amount. With this configuration, when a large eccentric load is applied to the cam receiving plate (10) during pressing by the rotary cam (9), the cam receiving plate (10) is slightly tilted, and the bore (5a) of the guide tube (5) is reduced. ) It can slide smoothly inside, and the cam receiving plate
The weight and vertical dimension of (10) can be minimized.

A downward spherical surface (10a) is formed at the center of the lower surface of the cam receiving plate (10). A cap-shaped inner shim (11) is detachably fitted to the shaft end of the engine valve (1) from above, and a concave surface (11a) formed on the upper surface thereof.
Is in close contact with the spherical surface (10a) of the cam receiving plate (10).

The concave surface (11a) and the spherical surface (10a) have the same curvature. (12) is an oil guide hole for supplying lubricating oil to the contact surface between the spherical surface (10a) and the concave surface (11a).

According to the first embodiment, since the cam receiving plate (10) has a disk shape and does not have a cylindrical body like the conventional tappet, the weight of the valve train is reduced accordingly. And the allowable engine speed can be increased.

Further, since the thickness of the cam receiving plate (10) is minimized, the vertical dimension of the guide tube (5) can be made shorter than the conventional dimension. As a result, the vertical dimension of the cylinder head, the total length of the engine valve (1), the valve spring (6)
The vertical size (number of turns) of the engine and the vertical size of the entire valve train can be reduced, and the height of the engine after assembly can be reduced.

Furthermore, since the engine valve (1) is driven via the inner shim (11), sliding wear of the end surface of the shaft portion (1a) can be prevented.

Since the contact area between the cam receiving plate (10) and the inner shim (11) is large and the surface pressure is reduced, the contact surfaces are less worn.

Since the cam receiving plate (10) and the inner shim (11) are in contact with each other on the spherical surface, the cam receiving plate (10) is rotated by the rotating cam (9).
When trying to tilt when pressed by, the cam support plate (10)
It will slide against the inner shim (11).

Therefore, it is possible to prevent an eccentric load from the cam receiving plate (10) from acting as a bending stress directly on the engine valve (1).

FIG. 2 shows a second embodiment of the present invention. Second
In the embodiment, contrary to the above embodiment, the inner shim (13) side is a spherical surface (13a), and the cam receiving plate (14) side is an upward concave surface (14a).
As a result, they are in close contact with each other. Also in the second embodiment, it is possible to obtain the same operational effects as the first embodiment.

In the first and second embodiments, the valve clearance is adjusted by the cam receiving plates (10) (14) or the inner shim (11).
This can be done by changing the thickness of (13).

FIG. 3 shows a third embodiment of the present invention. Third
In the embodiment, the hemispherical concave hole (15
The steel ball (16) is rotatably fitted to the (a) and is retained, and the lower surface of the steel ball (16) is fitted to the upper end of the inner shim (17) fitted to the shaft end of the engine valve (1). It is in close contact with the concave surface (17a). Also in the third embodiment, the same operational effects as those of the above embodiment can be obtained.

FIG. 4 shows a fourth embodiment of the present invention. Fourth
In the embodiment, the cam receiving plate (18) is formed of a light metal material such as an aluminum alloy or a magnesium alloy, and has a disc-shaped recessed hole (18a) formed in the upper surface and an upward recessed hole (18a) formed in the center of the lower surface. 18a) and shim (19) made of hard metal respectively
And the chip (20) are fitted together.

The shim (19) is removably fitted in the recess (18b) in order to adjust the valve clearance by changing its thickness. Insert the tip (20) with the caulking meat (21)
8b) is firmly fitted, and the lower surface of the tip (20) is a downwardly sloping spherical surface (20a). In addition,
The spherical surface may be formed on the axial end surface of the engine valve (1).

In the fourth embodiment as well, the same operational effects as the above-mentioned respective embodiments can be obtained, and since the cam receiving plate (18) is made of a light metal, the valve operating system is different from the above-mentioned respective embodiments. The weight of is further reduced. Also, adjust the valve clearance by adjusting the shim (1
It can be easily done by replacing only 9).

As in the fourth embodiment, the cam receiving plate
When (18) is made of light metal, it is preferable to perform surface treatment with a wear resistant material in order to improve wear resistance of the outer peripheral surface.

FIG. 5 shows a fifth embodiment of the present invention. Fifth
The embodiment is a modification of the fourth embodiment, in which the shaft end of the engine valve (1) is a spherical head (22), and the spherical head (22)
Is brought into close contact with the upward concave hole (23a) having the same curvature as the ball head (12) of the tip (23).

By doing so, the contact area between the engine valve (1) and the tip (23) is increased, so that the wear of the contact surfaces between them can be suppressed.

Also, as in the first and second embodiments, when the cam receiving plate (18) is about to tilt, the cam receiving plate (18) slides with respect to the engine valve (1), so the cam receiving plate (18) slides. Unbalanced load from (18) is prevented from acting as a bending stress directly on the engine valve (1).

[0037]

According to the present invention, the following effects can be obtained. (a) Since the cam receiving plate for driving the engine valve does not have a cylindrical body like the conventional tappet, the valve train can be made lightweight and compact.

(B) As a result, the allowable rotational speed of the engine can be increased, and the vertical dimension of the guide cylinder for guiding the cam receiving plate, the cylinder head, and the valve operating system incorporated therein can be reduced, and the engine alone The height is small.

(C) Since the engine valve is in contact with the cam receiving plate via the inner shim, the shaft end of the engine valve can be prevented from being worn.

(D) According to the second and third aspects of the invention, a large unbalanced load is prevented from acting on the engine valve, and the contact area between the cam receiving plate and the inner shim is large. Wear on the contact surface can be reduced.

(E) According to the invention described in claim 4, the valve train can be further reduced in weight without impairing the wear resistance of the contact surface between the rotary cam and the engine valve in the cam receiving plate.

[Brief description of drawings]

FIG. 1 is a central vertical sectional front view of a main part showing a first embodiment of the present invention.

FIG. 2 is a front view of the central longitudinal section of the main part of the second embodiment.

FIG. 3 is a center vertical sectional front view of the main part of the third embodiment.

FIG. 4 is a central vertical sectional front view of the main part, similarly showing the fourth embodiment.

FIG. 5 is a center vertical sectional front view of the main part of the fifth embodiment.

FIG. 6 is a central longitudinal front view showing a main part of a conventional direct-acting valve operating device.

[Explanation of symbols]

 (1) Engine valve (1a) Shaft (2) Annular groove (3) Cotter (4) Spring retainer (5) Guide tube (5a) Bore (6) Valve spring (9) Rotating cam (10) Cam receiving plate ( 10a) Spherical surface (11) Inner shim (11a) Concave surface (12) Oil guide hole (13) Inner shim (13a) Spherical surface (14) Cam receiving plate (14a) Concave surface (15) Cam receiving plate (15a) Recessed hole (16 ) Steel ball (17) Inner shim (17a) Recessed surface (18) Cam receiving plate (18a) Recessed hole (18b) Recessed hole (19) Shim (20) Tip (20a) Spherical surface (21) Crimped meat (22) Ball head Part (23) Chip (23a) Recessed hole

Claims (4)

[Claims] 1. An upper end portion of a shaft portion of an engine valve assembled by a cotter, a spring retainer, and a valve spring being constantly urged upward in a cylinder head is housed in a guide cylinder integral with the cylinder head. Then, inside the guide cylinder, a cam receiving plate of a required thickness can be slid up and down, with the upper surface contacting the rotating cam and the lower surface center contacting the inner shim fitted to the shaft end of the engine valve. A direct-acting valve operating device for an internal combustion engine, characterized in that 2. The direct acting valve operating system for an internal combustion engine according to claim 1, wherein the cam receiving plate and the inner shim are in spherical contact with each other. 3. A sphere is rotatably fitted in a concave hole provided in the center of the lower surface of the cam receiving plate, and the lower surface of the sphere is brought into close contact with the upper surface of the inner shim. Direct-acting valve operating system for internal combustion engines of the above. 4. The cam receiving plate is made of a light metal material, and a hard shim is provided in a concave hole provided in the upper surface of the cam receiving plate that comes into contact with the rotary cam, and a hard chip is provided in a concave hole provided in the center of the lower surface. The direct-acting valve operating device for an internal combustion engine according to claim 1, wherein the direct-acting valve operating device and the direct-acting valve operating device are fitted together.