JPH085287Y2 - Rattan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a lash adjuster used as a hydraulic valve lifter such as an intake and exhaust valve of an internal combustion engine.

[Prior art]

Conventionally, as a hydraulic valve lifter such as an intake / exhaust valve of an overhead cam type internal combustion engine, as shown in FIG. 3, a valve 1 is opened and closed by interposing a lash adjuster 4 at the tip of a rocker arm 3 which is rocked by a cam 2. I am trying to do it.

This lash adjuster 4, as shown in FIG.
The cylinder 5 fitted in the rocker arm 3 and the piston 6 slidably guided in the cylinder 5 form a kind of cylinder device. A hydraulic chamber 7 is formed inside the piston 6, and a ball 9 is provided so as to open and close a communication hole 8 formed at the top of the piston 6, so that a pressure is generated between the cylinder 5 and the piston 6. A chamber 11 is formed.

Although not shown, the ball 9 is in light contact with the communication hole 8 by a spring. Further, the spring 10 provided in the cylinder 5 elastically presses the piston 6 in the direction of coming out of the cylinder 5.

For example, regarding the valve opening operation, when the rocker arm 3 descends and pushes the upper end surface of the valve 1 through the lash adjuster 4 to push down the valve 1, the ball 9 closes the communication hole 8 and therefore the pressure generating chamber 11 The inside does not contract any further, so that the entire lash adjuster 4 becomes a rigid body, and the rocker arm 3 transmits the force for opening the valve 1.

On the other hand, when the rocker arm 3 rises and the valve 1 is closed by the elastic force of the valve spring 12, the piston 6 is pushed up by the spring 10. At this time, the hydraulic pressure of the hydraulic chamber 7 formed in the piston 6, that is, the inside of the oil gallery. The piston 6 ascends in the cylinder 5 while supplying the oil into the pressure generating chamber 11 with the hydraulic pressure.

Therefore, even if the valve 1 is closed, the upper end surface of the valve 1 and the cylinder member 5 are always in contact with each other, that is, the valve gap can always be zero when opening and closing the valve.

By the way, when the internal combustion engine rotates at a high speed, the valve 1 does not follow the movement of the rocker arm 3, that is, the lash adjuster 4, and a so-called valve jump occurs.
Then, although the valve 1 is open, no pressure is applied to the pressure generating chamber 11, and a large amount of oil flows into the pressure generating chamber 11 from the hydraulic chamber 7 so that the valve 1 cannot be closed and is left open. (Called "oil up phenomenon").

In order to prevent this, it is necessary to secure the valve jump limit to a higher rotation than usual, and therefore, the valve spring 12 is strengthened. However, this strengthening of the valve spring 12 imposes severe conditions on the valve system.

That is, the contact between the upper end surface of the stem of the valve 1 that linearly reciprocates and the contact surface of the piston 5 of the lash adjuster 4 provided at the tip of the rocker arm that swings about the rocker shaft is spherical opposite plane. However, because of the so-called point contact state, the surface pressure also increases, and problems such as pitching and wear occur.

In order to prevent the above-mentioned drawbacks, in the conventional technology, a means such as sticking a high hardness material to the contact surface or overlaying is applied, which results in a very high cost.

JP-A-59-147807 has been proposed as a means for reducing the surface pressure of the contact surface with the upper end surface of the valve 1 as described above. This relates to an internal structural member for a hydraulic clearance compensating member of an internal combustion engine, which is in contact with a convex spherical surface vs. a concave spherical surface, but this device is also basically a point contact, and an elastic deformation of the contact portion. Therefore, the contact area increases and the surface pressure lowers than the contact between the flat surface and the spherical surface, but there is a problem that the surface pressure does not decrease as in the case of the flat surface.

Further, in this invention, it is necessary to fit a cap having a concave spherical surface on the stem of the valve in order to make spherical contact, and such a cap will be attached by caulking to the upper end of the stem, and it will not be possible to move the rocker arm. There is a problem in that the caulking portion may be broken due to pushing up from the valve side in order to cope with it and reliability is insufficient.

[Purpose of device]

The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to reduce the wear of the valve end surface by making the valve stem upper end surface and the lash adjuster end surface contact each other in a plane-to-plane manner. It is what

[Constitution of device]

The present invention for achieving the above object is formed at the tip of the rocker arm 3 in a lash adjuster 4 interposed between one end of the rocker arm 3 swung by the cam 2 and the end surface of the stem of the valve 1. Inside the concave spherical surface receiving portion 3a, the surface of the convex spherical surface 5a is formed to match the concave spherical surface receiving portion 3a, and the cylinder 5 having the communication hole 8 at the top is slidably fitted. A piston 6 which is in sliding contact with the end face of the stem is fitted, and a hydraulic chamber 7 communicating between the top of the cylinder 5 and the concave spherical surface receiving portion 3a is connected to an oil gallery.
And is accommodated in the cylinder 5 to form the communication hole 8
A ball 9 that abuts and opens and closes and a spring 10 that urges the piston 6 in a direction to push the piston 6 from the cylinder 5 are provided, and the oil in the hydraulic chamber 7 presses the ball 9 to open the communication hole 8. It is intended to provide a lash adjuster which is made to flow into the cylinder 5 to adjust the pressing force of the stem by the piston 6.

That is, in the lash adjuster 4 according to the present invention, the outer surface of the cylinder 5 is a convex spherical surface 5a, which is rotatably received by the concave spherical surface receiving portion 3a provided at the tip of the rocker arm 3, and the lash adjuster 4 is a rocker arm. 3 is supported by a kind of spherical bearing, and the contact surface 6A (flat surface) of the end surface of the piston 6 is configured so as to accurately face the flat upper end surface of the valve stem.

Therefore, the contact surface 6A of the piston 6 and the upper end surface of the stem of the valve 1 are in plane-to-plane contact, so that they contact each other over a wide area.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of an essential part showing a valve of an overhead cam type internal combustion engine having a lash adjuster of the internal combustion engine according to one embodiment of the present invention. 2 is a longitudinal sectional view of an enlarged main part of FIG.

This lash adjuster 4 has a rocker arm 3 and a valve 1 which are swung by a cam 2 as in the conventional example shown in FIG.
It is provided between the upper end surface of the stem and. The piston 6 has a flat contact surface 6A and is slidably guided in the cylinder 5 in its longitudinal direction. The outer surface of the cylinder 5 is formed into a convex spherical surface 5a, which is rotatably fitted in a concave spherical surface receiving portion 3a provided on the rocker arm 3.

A piston 6 is placed inside a cylinder 5 whose outer surface is formed into a convex spherical surface 5a.
Are inserted to form a pressure generating chamber 11 between the two.
Inside the pressure generating chamber 11, there are provided a spring 10 that elastically pushes the piston 6 out of the cylinder 5 and a ball 9 (valve) that closes the communication hole 8 that opens to the hydraulic chamber 7 side.

The space at the top of the cylinder 5, which is fitted into the concave spherical surface receiving portion 3a, that is, the hydraulic chamber 7, communicates with the oil gallery through a passage (not shown).
The hydraulic pressure is constantly working inside. Further, as shown in FIG. 2, the small spring 10a is arranged so that the ball 9 is pressed toward the communication hole 8 side.
Is provided.

Valve 1 of lash adjuster 4 having the above configuration
Since the function of opening and closing is substantially the same as that of the conventional example shown in FIG. 3, the description thereof will be omitted.

In the lash adjuster 4 of the present invention, the outer surface of the cylinder 5 is formed into a convex spherical surface 5a and is received by the convex spherical surface receiving portion 3a provided on the rocker arm 3, so that the lash adjuster 4 can be rotated in any direction with respect to the rocker arm 3. It is configured.

As described above, the entire lash adjuster 4 is a convex spherical surface.
Since 5a is formed and can freely rotate, the contact with the end surface of the stem of the valve 1 can be made flat, and the surface pressure of the contact surface can be reduced.

[Effect of device]

The lash adjuster 4 of the present invention is a concave spherical surface formed at the tip of the rocker arm 3 in the lash adjuster 4 interposed between one end of the rocker arm 3 swung by the cam 2 and the end surface of the stem of the valve 1. A cylinder 5 having a convex spherical surface 5a matching the concave spherical surface receiving portion 3a and having a communication hole 8 opened at the top is slidably fitted into the receiving portion 3a. A piston 6 which is in sliding contact with the end face is fitted, and a hydraulic chamber 7 which communicates with an oil gallery is formed between the top of the cylinder 5 and the concave spherical surface receiving portion 3a, and is accommodated in the cylinder 5 and the communicating hole 8 is formed.
A ball 9 that abuts and opens and closes and a spring 10 that urges the piston 6 in a direction to push the piston 6 from the cylinder 5 are provided, and the oil in the hydraulic chamber 7 presses the ball 9 to open the communication hole 8. It is configured to flow into the cylinder 5 and adjust the pressing force of the stem by the piston 6, and the following effects can be achieved.

Since the cylinder 5 fitted to the tip of the rocker arm 3 is formed on the convex spherical surface 5a, the cylinder 5 is supported by the spherical bearing. Therefore, since the piston 6 slidably supported by the cylinder 5 can be slid in any direction, the contact surface 6A of the piston 6 can be automatically directed to the upper end surface of the stem of the valve 1. .

Therefore, even if the upper end surface of the stem and the contact surface 6A of the piston 6 are flat surfaces, they can be accurately brought into contact with each other, so that the contact surface pressure can be reduced. Therefore, the wear of the upper end surface of the stem of the valve 1 is reduced, the life can be extended by that amount, and the internal combustion engine equipped with the lash adjuster 4 according to the present invention can be stably operated.

Further, since the contact surface pressure between the upper end surface of the stem of the valve 1 and the contact surface 6A of the piston 6 can be reduced, the pitching generated on the high pressure surface does not occur, so that the internal combustion engine can have a high load and high performance. Becomes

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an essential portion showing an overhead cam type drive valve having a lash adjuster of an internal combustion engine according to an embodiment of the present invention, and FIG. 2 is an enlarged vertical sectional view of the essential portion of the lash adjuster. FIG. 3 is a vertical cross-sectional view of a main part of a conventional overhead cam type valve, and FIG. 4 is an enlarged vertical cross-sectional view of the main part of FIG. 1 ... Valve, 3 ... Rocker arm, 3a ... Concave spherical surface receiving part, 4 ...
Rush adjuster, 5 ... Cylinder, 5a ... Convex spherical surface, 6 ...
Piston, 6A ... Contact surface, 7 ... Hydraulic chamber, 8 ... Communication hole, 9 ...
Ball, 10 ... Spring, 10a ... Spring, 11 ... Pressure generating chamber.

Claims (1)

[Scope of utility model registration request] 1. A lash adjuster (4) interposed between one end of a rocker arm (3) swung by a cam (2) and an end face of a stem of a valve (1), wherein a rocker arm (3) Concave spherical surface receiving part (3
A cylinder (5) having a surface formed into a convex spherical surface (5a) matching the concave spherical surface receiving portion (3a) and having a communication hole (8) opened at the top is slidably fitted in a), and further, A piston (6) slidingly contacting the end face of the stem in the cylinder (5)
The cylinder (5) and the concave spherical receiving part (3
A ball (9) which forms a hydraulic chamber (7) communicating with an oil gallery with a) and is housed in the cylinder (5) and abuts the communication hole (8) to open and close, and the piston. A spring (10) for urging (6) from the cylinder (5) is provided, and oil in the hydraulic chamber (7) presses the ball (9) to open the communication hole (8). Lash adjuster that adjusts the pressing force of the stem by the piston (6) by flowing it into the cylinder (5).