JPH0320487Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hydraulic valve gap adjustment device for an internal combustion engine.

A conventional device of this type includes a hollow cylindrical plunger with one end closed, which is slidably fitted into a cylinder fixed to the rocker arm, and which is fitted into the cylinder and has an orifice and a check valve at the lower end. It consists of a reservoir that together with the cylinder constitutes a reservoir chamber, the plunger, the reservoir, and the inner wall of the cylinder constitute a high-pressure chamber, and the reservoir chamber is communicated with the outside through a drain hole provided in the cylinder above the plunger. It is.

In such conventional devices, the volume of the reservoir chamber is small in proportion to the size of the cylinder, and the distance from the oil supply port of the reservoir chamber to the check valve is short, so oil containing air bubbles is supplied to the reservoir chamber. When this happens, the bubbles enter the high-pressure chamber through the orifice and check valve before they rise in the reservoir chamber, causing the high-pressure chamber's elastic modulus to become high and impeding normal valve gap function. .

Furthermore, since the reservoir chamber is small, when the high pressure chamber requires a large amount of oil at the time of starting the engine, there is a shortage of oil, which sometimes causes air to enter the high pressure chamber.

The present invention was developed by focusing on these conventional problems, and the reservoir chamber is enlarged by extending the reservoir into the hollow part of the plunger, and a check valve is provided at the bottom of this extension, thereby achieving the following: While minimizing the total length of the hydraulic valve gap adjustment device, the distance from the oil supply port to the check valve is increased, making it easier to separate oil and air bubbles in the reservoir chamber, and reducing the amount of air bubbles flowing into the high pressure chamber from the check valve. It has the characteristic that it can be used. Furthermore, since the capacity of the reservoir chamber can be increased, air intake into the high pressure chamber at the time of engine startup can be reduced. The air accumulated above the reservoir chamber is discharged to the outside together with the oil from a drain hole drilled above the cylinder, and even if oil containing air bubbles is continuously supplied, air will not accumulate in the reservoir chamber. Furthermore, the reservoir projecting into the high pressure chamber reduces the volume of the high pressure chamber, thereby reducing the displacement of the plunger due to the elasticity of the oil.

Hereinafter, the present invention will be explained based on the drawings.

First, the configuration shown in FIG. 1 will be described. The cylinder 3 is fixedly attached to the rocker arm 1, and the cylinder head hydraulic circuit communicates with an oil supply annular groove 4 around the cylinder via an oil passage 2 in the rocker arm. An upwardly open reservoir 5 is fitted into the cylinder, and the lower part of the reservoir 5 has a small diameter extension 5' extending downward, and at its lower end there is a check ball 6, a relief spring 7, and a retainer 8 that cooperate with an orifice. A check valve is provided. The open end of the reservoir contacts the top closing wall of the cylinder to form a reservoir chamber 9 therein.
The reservoir chamber 9 communicates with the oil supply annular groove 4 through an oil supply passage 10 of the cylinder and a reservoir oil supply port 11 provided in the reservoir 5 adjacent to its open end. The fitting gap between the reservoir and the cylinder is sealed by providing a ring-shaped seal 12 made of, for example, synthetic resin on the outer peripheral wall of the reservoir.

A plunger 13 is slidably fitted into the cylinder opposite the reservoir, and the extension of the reservoir with the check valve projects into the hollow part of the plunger. A high pressure chamber 16 is formed by the reservoir, plunger and cylinder, and a return spring 14 is placed between the reservoir and the plunger with a suitable set load. A stopper 15 is attached to the open end of the cylinder to prevent the plunger 13 from coming out of the cylinder.

A drain hole 18 is opened in the center of the top closed wall of the cylinder so as to communicate with the outside, and a leak prevention valve 19 is attached to this drain hole 18 with a slight gap.

FIG. 2 shows an embodiment in which a drain hole 18 is formed in the circumferential wall of the cylinder adjacent to the top closed end and a small amount of oil is discharged to the outside through a gap 20 between the cylinder body and the rocker arm. FIG. 3 shows an embodiment in which a small amount of oil is discharged to the outside by placing a flow rate control plate 21 supported by the inner wall of the reservoir just below the drain hole 18.

Assuming that the reservoir chamber 9 and the high pressure chamber 16 are filled with oil, when the engine valve opens according to the rotation of the cam 17, a load is applied to the plunger 13 due to the load of the valve spring, and the check ball valve 6 is completely closed. High pressure is generated in the high pressure chamber 16. The volume of the high pressure chamber decreases due to the elasticity of the oil in the high pressure chamber, and the plunger is slightly displaced by that amount. The oil in the high pressure chamber leaks slightly from the gap between the sliding surfaces of the cylinder 3 and the plunger 13, and the plunger 13 is further displaced by that amount.

When the engine valve is closed, the plunger 13 is pushed back by the return spring 14, the pressure in the high pressure chamber 16 drops below the pressure in the reservoir chamber 9, and the check ball valve 6 opens, allowing oil to flow from the reservoir chamber 9 into the high pressure chamber 16 through the orifice.

In the present invention, even if air bubbles are included in the oil supplied from the cylinder head hydraulic circuit, the distance between the oil supply port 11 of the reservoir and the check valve is long, so the oil that has entered the reservoir chamber 9 is The air bubbles 30 gather upward and escape to the outside through the gap between the drain hole 18 and the valve 19, thereby reducing the number of air bubbles in the oil entering the high pressure chamber through the check valve. Also,
Even when the high pressure chamber requires a large amount of oil when starting the engine, the large capacity of the reservoir chamber ensures that oil shortages are less likely to occur. In this way, the present invention can prevent the high-pressure chamber from sucking in air and significantly interfering with the gap adjustment function.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an example of the valve gap adjustment device for an internal combustion engine according to the present invention, Fig. 2 is a view similar to Fig. 1 showing another example, and Fig. 3 is a cross-sectional view showing yet another example. It is. 1...Rotzker arm, 3...cylinder, 5...
...Reservoir, 9...Reservoir chamber, 5'...Small diameter extension, 13...Plunger, 16...High pressure chamber.

Claims (1)

[Scope of utility model registration request] It consists of a hollow cylindrical plunger with one end closed and slidably fitted into the cylinder of the rocker arm, and a reservoir fitted into the cylinder and having an orifice and a check valve at the lower end and forming a reservoir chamber together with the cylinder, In a hydraulic valve gap adjustment device in which a plunger, a reservoir, and a cylinder circumferential wall constitute a high-pressure chamber, and the upper part of the reservoir chamber is communicated with a drain hole provided in the cylinder, the reservoir is used as a small-diameter extension inside the hollow part of the plunger. A valve gap adjusting device, characterized in that the check valve is provided at a lower end of the extension portion within the high pressure chamber.