JPH03260306A - Hydraulic type rush adjuster of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent retention of air in a high pressure chamber and over-flow of lubricating oil out of the high pressure chamber respectively by forming an air discharging hole whose both ends are opened to a pivot part and the high pressure chamber respectively on a plunger fitted slidably inside a body. CONSTITUTION:During a term when a cam 6a is not lifted, a plunger 13 fitted slidably in the body 12 of a hydraulic type rush adjuster 1 is projected by energizing force of a coil spring 14, and a rocker arm 8 is pushed up to abut on a cam. At this time, since pressure contact of a pivot part 21 with the rocker arm 8 is comparatively gentle, lubricating oil flows out little by little from an air discharging hole 22 formed on the axial center of the plunger 13. On the other hand, when the cam 6a is started to lift, since a check valve 15 for opening/closing the communicating hole 11 of the body 12 is closed to enclose a high pressure chamber 16, the plunger 13 pushed down by the rocker arm 8 is supported. As a result, the air discharging hole 22 is sealed so as to prevent flow-out of the lubricating oil.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a hydraulic lash adjuster used to constantly maintain a valve clearance at O in a valve train of an internal combustion engine, particularly to a base end of a swing arm type rocker arm. The present invention relates to an improvement in a hydraulic lash adjuster for supporting parts.

Conventional technology A swing arm type rocker arm is disposed between the intake/exhaust valve and the cam, and the base end of the rocker arm is swingably supported by a hydraulic type sure adjuster to improve valve clearance. A valve mechanism that always maintains O at all times has been known.

Japanese Utility Model Application Publication No. 6137409 discloses a configuration in which the oil reservoir chamber is formed as a part of the cylinder head, thereby eliminating the oil reservoir chamber inside the hydraulic lash adjuster and reducing its size. .

FIG. 6 shows an example of the configuration of this type of hydraulic lash adjuster, in which a high pressure chamber 33 is defined between a bottomed cylindrical body 31 and a plunger 32, and a check valve is installed in the high pressure chamber 33. Hydraulic oil or lubricating oil is introduced through 34. Further, the lower part of the plunger 32 is machined into a cylindrical shape so as to receive the coil spring 35. In this hydraulic lash adjuster, if air gets mixed into the high pressure chamber 33, it will cause malfunction, so normally, a fine air discharge hole 36 is formed through the upper surface of the high pressure chamber 33 in the radial direction of the plunger 32. Air is discharged from the air discharge hole 36 through the fitting gap between the plunger 32 and the body 31.

Problems to be Solved by the Invention As mentioned above, the plunger 3 that partitions the upper part of the high pressure chamber 33
A recess 37 for receiving the coil spring 35 is machined in the lower part of 2, but it is difficult to make the bottom surface of this recess 37, that is, the upper end surface 38 of the high pressure chamber 33, a completely flat surface due to machining constraints. , as shown in the figure, it becomes a loose conical surface.

Therefore, even if the air discharge hole 36 is provided on the outer periphery, a small amount of air remains near the top of the conical surface, making it impossible to completely discharge the air.

Therefore, there was a drawback that the automatic valve clearance adjustment function deteriorated and the noise increased.

Means for Solving the Problems Therefore, the present invention provides a bottomed cylindrical body that is fitted into a mounting hole of a cylinder head, a check valve disposed in a communication hole at the bottom of the body, and the body. a plunger that is slidably fitted to the inner periphery of the body and defines a high pressure chamber between it and the bottom of the body; a coil spring that is housed in the high pressure chamber and biases the plunger in the projecting direction; In a hydraulic lash adjuster for an internal combustion engine, the hydraulic lash adjuster for an internal combustion engine includes a pivot portion formed in a substantially hemispherical shape at the head of the plunger and fitted into a substantially hemispherical recess at the base end of the rocker arm.
It is characterized in that an air discharge hole is formed through the blanket, one end opening at the center of the pivot portion and the other end opening at the upper end of the high pressure chamber.

During a period in which the working cam is not lifted, the rocker arm base end and the pivot portion are in relatively weak pressure contact. Therefore,
The lubricating oil in the high-pressure chamber flows out from the air discharge hole little by little due to the supplied hydraulic pressure.

Therefore, even if air should enter the high pressure chamber, it will be quickly exhausted through the air exhaust hole.

On the other hand, when the cam starts to lift, the pivot portion comes into strong pressure contact with the substantially hemispherical recess on the rocker arm side, so that the air discharge hole is closed and lubricating oil is prevented from flowing out from the high pressure chamber.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows a hydraulic run-your-adjuster 1 according to the present invention.
This figure shows the overall configuration of a valve mechanism with It is biased in the closing direction.

A camshaft 6 is disposed above the valve 2, more specifically, on a substantially extended line of the valve stem 21, and a rad cover 7 is attached to the cylinder head 3 on the upper surface thereof so as to cover the entire valve mechanism.

Then, the cam lift of the camshaft 6 is adjusted to the valve 2.
A rocker arm 8 in the form of a swing arm is provided for transmitting the signal.

The rocker arm 8 has one base end supported by a hydraulic run-your-adjuster l so as to be swingable, the other swinging end abutting the stem end 2b of the valve 2, and the back surface facing the cam 6a. is in contact with. Therefore, when the cam 6a lifts, the rocker arm 8 swings using the base end on the side of the hydraulic lash adjuster l as a fulcrum, thereby pushing down the valve 2. A substantially hemispherical concave portion 9 is formed on the lower surface of the base end of the rocker arm 8, and this portion is supported by the hydraulic lash adjuster 1.

As shown in detail in FIG. 2, the hydraulic lash adjuster 1 includes a bottomed cylindrical body 12 with a communication hole 11 opened at the center of the bottom, and a plunger slidably fitted into the inner circumference of the body 12. 13, a coil spring 14 that biases the plunger 13 in the projecting direction, and a check valve 15 that opens and closes the communication hole 11. The body 12 has the plunger 3 and the check valve inside. 15 defines a high pressure chamber 16.

The check valve 15 is composed of a spherical valve body 17, a return spring 18, and a retainer 19 that holds them. Fixed.

A coil spring 14 is provided at the bottom of the plunger 13.
A recess 20 is formed so that the upper part of the recess 20 fits into the recess 20, so that only the outer cylindrical wall 132L remains.

Further, a substantially hemispherical pivot portion 21 is formed at the head of the plunger 13. This pivot portion 21 has a radius of curvature approximately equal to that of the substantially hemispherical recess 9 on the rocker arm 8 side described above, and is adapted to fit relatively tightly into each other.

A relatively narrow air discharge hole 22 is formed through the plunger 13 along the axial center thereof.

That is, the air discharge hole 22 has a lower end opening at the center of the bottom surface of the recess 20 having a loose conical surface, and an upper end opening at the center of the pivot section 21 .

In addition, 23 is a seal ring attached to the outer periphery of the body 12,
24 is the body 1 to prevent the plunger 13 from coming off.
2. This is a cover attached to the edge of the opening.

The hydraulic lash adjuster 1 configured as described above is fitted into a mounting hole 25 opened on the upper surface of the bottom wall of the cylinder head 3 as shown in FIG. Lubricating oil is supplied into the high pressure chamber 16 through the communication hole 11.

Next, the operation of the above configuration will be explained.

First, during the period when the cam 6a is not lifted, the plunger 13 protrudes by the biasing force of the coil spring 14 and pushes up the base end of the rocker arm 8, so that the back surface of the rocker arm 8 and the cam 6a are always in contact. That is, the valve clearance becomes O. At this time, the high pressure chamber 16 is filled with lubricating oil pumped by an oil pump (not shown).

In addition, in this state, the pivot portion 21 and the rocker arm 8
Since the pressure contact with the side recess 9 is relatively gentle, the lubricating oil flows out in very small amounts through the air discharge hole 22 due to the oil pressure of the lubricating oil itself that is pumped from the oil pump.

After this lubricating oil lubricates the sliding motion between the pivot portion 21 and the recess 9, it flows out through the minute gap between them.

Therefore, even if air should enter the high pressure chamber 16, it will be quickly discharged to the outside through the air discharge hole 22 together with a small amount of lubricating oil. In particular, since the lower end of the air discharge hole 22 opens at the center of the bottom surface of the gently conical recess 20, the air can be completely discharged without remaining inside the high pressure chamber 16.

On the other hand, when the cam 6a starts to lift, the rocker arm 8 tries to push down the plunger I3 due to the reaction force of the valve spring 5, but the check valve 15 closes and the high pressure chamber 16
Since it is sealed, the above reaction force is supported by hydraulic pressure. At this time, the recess 9 on the rocker arm 8 side and the pivot portion 2
1 and the air exhaust hole 22 because there is strong pressure contact all around the circumference.
The outer side is in a soled state and the lubricating oil is prevented from flowing out.

Therefore, no more lubricating oil than necessary flows out from the high pressure chamber 16 during the lift of the cam 6a, and the desired valve lift amount can be reliably obtained.

Next, FIG. 3 shows an embodiment in which grooves 27 are formed along the circumferential direction on the surface of the pivot part 21 in order to improve the sole property between the pivot part 21 and the substantially hemispherical recess 9 on the rocker arm 8 side during cam lift. An example is shown. In this example,
Two grooves 27 are formed on the top and bottom, and the labyrinth effect improves the sole properties. Incidentally, the above R27 may be formed at the same time during casting or the like, or may be secondarily machined.

4 and 5 show an example in which a similar groove 28 is formed on the inner periphery of the substantially hemispherical recess 9 on the rocker arm 8 side in correspondence with the pivot portion 21 as described above.

Effects of the Invention As is clear from the above explanation, in the hydraulic lash adjuster for an internal combustion engine according to the present invention, air can be discharged from the highest position of the high pressure chamber. There is no accumulation of air, and malfunctions caused by air can be prevented.

In addition, since the rocker arm is used as a kind of on-off valve and the air exhaust hole is closed during cam lift, lubricating oil does not flow out from the high pressure chamber more than necessary, making it possible to secure the desired valve lift amount. .

[Brief explanation of drawings]

Fig. 1 is a sectional view of the entire valve train equipped with a hydraulic run-your-adjuster according to the present invention, Fig. 2 is a half-sectional view of the hydraulic lash adjuster, and Fig. 3 shows a different embodiment of the hydraulic lash adjuster. 4 is a partially cutaway sectional view showing a rocker arm with a groove provided in the recess, FIG. 5 is an enlarged sectional view of the main part, and FIG. 6 is a half sectional view of a conventional hydraulic lash adjuster. It is a diagram. l... Hydraulic lash adjuster, 8... Rocker arm, 9... Recess, 12... Body, 13... Plunger, 14... Coil spring, 15... Check valve, 16... ... High pressure chamber, 21 ... Pivot part, 22
...Air exhaust hole. Tsuirrespudding 2 Honorable Ben Piho', Tokkoku 1 -51=

Claims (1)

[Claims] (1) A cylindrical body with a bottom that is fitted into the mounting hole of the cylinder head, a check valve installed in the communication hole at the bottom of this body, and a check valve that is slidably fitted to the inner circumference of the body. a plunger defining a high-pressure chamber between the plunger and the bottom of the body; a coil spring housed in the high-pressure chamber and biasing the plunger in a projecting direction; and a substantially hemispherical head formed on the head of the plunger. a hydraulic lash adjuster for an internal combustion engine, the hydraulic lash adjuster for an internal combustion engine having a pivot portion that fits into a substantially hemispherical recess at the base end of the rocker arm, one end opening in the center of the pivot portion, and the other end opening at the high pressure A hydraulic lash adjuster for an internal combustion engine, characterized in that an air discharge hole opening at the upper end of the chamber is formed through the plunger.