JPH0327725B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic latch adjuster used in a support portion of a rocker arm in a valve train of an internal combustion engine.

Conventionally, in an overhead valve type valve train, a lash adjuster has been used to automatically adjust the clearance between the intake/exhaust valve and the rocker arm in a closed state.

In addition, in order to prevent the valve system from being compressed by force generated in the cam base circle due to vibration of the cam base circle or deflection of the camshaft, resulting in poor valve seating, a free ball type latch adjuster without a check ball spring is used. It existed.

In conventional free-ball type latch adjusters, the valve is automatically opened and closed by the flow of oil. There were times when it was impossible to follow.

In particular, in engines such as motorcycle engines, which have high rotation speeds, high output, and are limited in size, the lash adjusters themselves are becoming faster and smaller.
A small flow of oil makes it difficult for the check ball to move, resulting in a large sinking of the latch adjuster, resulting in poor opening of the valve train, and poor followability at high speeds.

The present invention relates to an improvement of a hydraulic lash adjuster that overcomes these difficulties, and its purpose is to provide a hydraulic lash adjuster that has excellent followability even in high-speed ranges and is highly durable. At the point.

An embodiment of the present invention illustrated in FIGS. 1 and 2 will be described below.

Reference numeral 1 denotes a hydraulic latch adjuster used in a four-cycle gasoline engine for motorcycles.The adjuster body 2 of the latch adjuster 1 has an open end 2a, and is adapted to be fitted into an adjuster inserting tube (not shown). ing.

Further, a leak down plunger 3 and a plunger cap 4 are slidably fitted into the adjuster body 2 of the cylindrical body.
The plunger cap 4 is integrally connected to each other by electron beam welding to form a plunger.

Further, a retainer cap 5 is fitted onto the open end 2a of the adjuster body 2 so as to prevent the plunger cap 4 from protruding beyond a certain length.

Furthermore, a hollow cylindrical reservoir chamber 9 and a high pressure chamber 10, which will be described later, are provided at the base of the leak down plunger 3.
A communication passage 21 is formed to communicate with each other, and a valve seat 3a is formed at the opening of this communication passage 21 on the high pressure chamber 10 side.
A check ball cage 6 is attached to the tip of the check ball cage 6, and a check ball 7 made of ceramic is fitted inside the check ball cage 6.

Further, a plunger spring 8 that urges the plungers 3 and 4 toward the open end of the adjuster body 2 via the check ball cage 6 is interposed in a high pressure chamber 10 between the check ball cage 6 and the bottom portion 2b of the adjuster body 2. .

Further, a hollow cylindrical reservoir chamber 9 is formed in the leak down plunger 3 and the plunger cap 4, and oil supply holes 2c are formed in the side walls of the adjuster body 2 and the plunger cap 4 so as to communicate with the reservoir chamber 9. 4c is provided.

Furthermore, the outer end 4a of the plunger cap 4
is formed into a spherical shape, and the spherical outer end 4a is provided with an oil passage 4b that communicates with the reservoir chamber 9, and a rocker arm (not shown) can be pivoted or brought into contact with the spherical outer end 4a. It's summery.

Since the embodiment shown in FIGS. 1 and 2 is configured as described above, when the engine (not shown) is in operation, the oil passage (not shown) and the oil supply holes 2c, 4c are supplied from the oil pump (not shown). Oil is supplied to the reservoir chamber 9 through the oil reservoir chamber 9. The oil in the reservoir chamber 9 is sent to the high pressure chamber 10 of the adjuster body 2 through the communication path 21, the valve seat 3a, and the check ball 7, and the high pressure chamber 10 is filled with oil. The remaining oil is sent through the oil passage 4b to the space between the rocker arm (not shown) and the spherical outer end 4a of the plunger to lubricate the gap.

If a clearance occurs between the Rotsuker arm (not shown), the intake/exhaust valve, and the cam,
When the plunger cap 4 is pushed out by the spring force of the plunger spring 8, the high pressure chamber 10
Due to the pressure drop inside the valve seat 3a, the check ball 7
The oil in the reservoir chamber 9 is further away from the high pressure chamber 1.
Supplied within 0.

Further, when the cam ridge of the cam (not shown) approaches the rocker arm and the rocker arm is pressed, the leak down plunger 3 and the plunger cap 4 are pushed in, so the high pressure chamber 10
The oil inside is pressurized to a high pressure and is returned to the reservoir chamber 9 through the oil supply hole 4c from the gap between the leak down plunger 3 and the plunger cap 4 and the adjuster body 2.

By repeating such operations, the leak down plunger 3 and the plunger cap 4 reciprocate,
The fulcrum of the Rotzker arm (not shown) is changed,
Always held at zero rush.

If the vibration of the cam base circle or the deflection of the camshaft generates a force that compresses the valve train in the cam base circle, causing valve seating failure,
The check ball 7 floats in response to fluctuations in the oil pressure difference acting on both sides of the check ball 7 across the valve seat 3a, and the valve seat 3a is opened and closed appropriately, thereby preventing the valve from being improperly seated.

Furthermore, since the check ball 7 is made of ceramic, its specific gravity is lower than that of a steel check ball, and the check ball 7 can move by following a slight flow of oil.

In particular, since the lash adjuster 1 of this embodiment is used in a small, high-speed four-stroke gasoline engine for motorcycles, the lash adjuster 1 itself is small and the oil flow rate passing through the valve seat 3a is small, but it is lightweight. The check ball 7 has a high tracking ability even at high speeds due to its small inertia.

In addition, since the check ball 7 is made of ceramic, it is highly wear resistant and lightweight, and is extremely durable.

In the embodiment shown in FIGS. 1 and 2, the outer end 4a of the plunger cap 4 is formed into a spherical shape and serves as a support for the rocker arm. However, as shown in FIG. Hydraulic lash adjuster 1 in which one end 12b of 12 is formed into a spherical shape and this is used as a supporting part of a rocker arm.
The present invention can also be applied to 1.

Note that the numerals added by the number 10 to the numbers assigned to each part of the embodiment shown in Figures 1 and 2 are assigned to the corresponding parts of the embodiment shown in Figure 3. I am forced to do so.

The present invention may also be applied to a conventional hydraulic latch adjuster in which a check ball cage and a check ball are interposed with a check ball spring, in which the check ball is made of ceramic.

In this embodiment, by increasing the natural frequency of the check ball, it is possible to improve followability and durability under high pressure.

The present invention includes an adjuster body having an open end, a plunger slidably fitted to the inner circumferential surface of the adjuster body, and a high-pressure chamber defined by the adjuster body base and the plunger so as to bias the plunger in an extrusion direction. a plunger spring interposed in the plunger; a check ball provided on the high pressure chamber side so as to be able to freely open and close a communication passage communicating between the space inside the plunger and the high pressure chamber; and a check ball for holding the check ball. In the hydraulic lock adjuster having a check ball cage, the material of the check ball is made of ceramic, the weight of the check ball is reduced, and the check ball moves by following the flow of a small amount of oil. The communication path can be automatically opened and closed. Therefore, a hydraulic latch adjuster with high followability can be obtained in a small high-speed engine.

Further, in the present invention, since the check ball is made of ceramic, it is lightweight and has high wear resistance, has low impact when opening and closing the valve, and has high durability.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional side view illustrating one embodiment of a hydraulic lash adjuster according to the present invention, FIG. 2 is an enlarged longitudinal sectional side view of its main parts, and FIG. 3 is a longitudinal sectional view of another embodiment of the present invention. FIG. 1...Hydraulic latch adjuster, 2...Adjuster body, 3...Leak down plunger,
4... Plunger cap, 5... Retainer cap, 6... Check ball cage, 7... Ceramic check ball, 8... Plunger spring, 9... Reservoir chamber, 10... High pressure chamber,
11... Hydraulic latch adjuster, 12... Adjuster body, 13... Leak down plunger, 14... Plunger, 15... Retainer cap, 16... Check ball case, 17...
...Ceramic check ball, 18...Plunger spring, 19...Reservoir chamber, 20...
Hyperbaric chamber, 21... communication passage.

Claims (1)

[Claims] 1. An adjuster body having an open end, a plunger slidably fitted to the inner circumferential surface of the adjuster body, and a high-pressure chamber defined by the adjuster body base and the plunger so as to bias the plunger in the extrusion direction. a plunger spring installed in the high pressure chamber; a check ball installed on the high pressure chamber side so as to be able to open and close a communicating path communicating between the space inside the plunger and the high pressure chamber; and a check ball for holding the check ball. 1. A hydraulic latch adjuster having a ball cage, wherein the check ball is made of ceramic.