JPH0244004Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a valve stop device for an internal combustion engine, and more specifically relates to an improvement of a valve stop device used in a variable displacement engine. .

[Conventional technology]

In general, a valve stop device for a variable displacement engine reduces the number of cylinders to which fuel is supplied depending on the engine operating conditions, reducing the operating displacement and also operating the valves corresponding to the cylinders to which fuel supply has been stopped. This is to reduce fuel consumption by stopping the engine.

By the way, exhaust brakes are conventionally used in diesel engines for trucks. For example, as shown in Fig. 1, a butterfly valve 2 is attached to an exhaust manifold 1, and by closing this butterfly valve 2, the engine braking force is applied. It is something that enhances. As a result, the pressure inside the exhaust pipe 1a increases, and the exhaust valve 3 releases the exhaust pressure P on the cam base dial 4.
This causes the cylinder to be lifted (protruded) into a cylinder (not shown).

[The problem that the idea aims to solve]

However, when the valve stop device 5 is used in a variable displacement engine equipped with the exhaust brake, when the exhaust valve 3 is lifted on the cam base dial 4, the valve is operated at the lifted position. Bracket 7 supporting rocker arm 6 of the mechanism
Pressurized oil pushes the check ball provided at the bottom of the plunger 20 into the high pressure chamber 23, which is partitioned by the slider 8 whose one end is fixed to Automatically installed. Therefore, the rocker arm shaft 12 is fixed in a state where the rocker arm 6 is pushed up by the amount of pressure oil introduced via the slider 8. For this reason, the exhaust valve 3 sometimes remained open and did not close.

Further, when the valve opening/closing operation is performed using the rocker arm shaft 12 that has been lowered as a fulcrum by the above-described operation, the lifted exhaust valve 3
The worst situation will occur in which the exhaust valve 3 will be damaged due to interference with the piston (not shown).

Further, the above problem also occurs in diesel engines and gasoline engines that are not equipped with an exhaust brake when so-called bounce occurs. In FIG. 1, 13 is a valve stem, 14 is a solenoid that controls the pressure oil in the hydraulic lifter 10 via a needle valve 15, and 16 is an actuator.

[Purpose of invention]

This invention was developed to solve the problems of conventional valve stop devices, and its purpose is to stop the valve even when an abnormal lift occurs on the cam base dia of the exhaust valve. An object of the present invention is to provide an intake/exhaust valve stop device for an internal combustion engine that maintains the opening/closing operation of the valve in a normal state and prevents accidents such as damage to the exhaust valve.

[Means to solve the problem]

The valve stop device for an internal combustion engine according to the present invention includes a cylinder fixed to the lower surface of the cylinder head and opened to the valve side, and a plunger fixed concentrically to the inside of the cylinder with a gap therebetween.
The slider has one end fixed to a bracket that swingably supports the rocker arm, and the other end is fluid-tightly fitted into the gap, and a check valve that opens and closes an orifice passage formed in the plunger. The hydraulic lifter is configured to maintain a high pressure inside the hydraulic lifter, and a member is provided between the plunger and the slider for regulating the range of movement of the plunger and a slider that slides on the surface of the plunger. .

As the member regulating the range of movement of the slider, a device is used that has a structure in which the thickness of the upper part of the plunger is reduced to provide a stepped portion, and a ring-shaped member is further provided on the inner surface of the slider to abut the stepped portion. However, it is not limited to this.

[Effect]

By regulating the relative movement distance between the plunger 20 and the slider 8, that is, the movable position of the bracket 7, which is a member that supports the rocker arm 6,
It is possible to prevent the valve (exhaust valve 3) pressed by the rocker arm 6 from abnormally lifting (protruding) into the cylinder.

〔Example〕

Hereinafter, embodiments of this invention will be described with reference to the accompanying drawings.

FIG. 2 shows an embodiment of the hydraulic lifter 10 in a variable displacement engine, where 7 is a bracket that swingably supports the rocker arm 6, and the lower end of the slider 8 is inserted into a recess formed at the upper end of the bracket. are fitted and fixed. This slider 8 is a type of cylinder made of a cylindrical body with a bottom.

On the other hand, the cylinder 1 is located on the bottom surface of the cylinder head 9.
1 (also referred to as a sleeve) and a plunger 20 is fixed in a double structure concentrically with a gap inside this, and in the gap between the outer surface of the plunger 20 and the inner surface of the cylinder 11 The upper part of the slider 8 is slidably fitted into the slider 8.

The lower end of the plunger 20 is reduced to form an orifice passage 20a, a valve seat 26 is fixed at the outlet of the orifice passage 20a, and a check ball 21 is pressed into the valve seat 26 via a spring 25. This opens and closes the orifice passage 20a.

The check ball 21 separates a low pressure chamber 22 within the plunger 20 from a high pressure chamber 23 within the slider 8. In addition, the high pressure chamber 23
Inside, a spring 24 is inserted between the plunger 20 and the slider 8.
The position of the bracket 7 is fixed by the pressure of the pressure oil introduced into the high pressure chamber 23, so that the rocker arm 6 can follow the movement of the cam. .

Further, a needle valve 15 operated by a solenoid 14 is passed through the interior of the plunger 20, and the tip of the needle valve 15 pushes down a check ball 21 that closes off the orifice passage 20a, thereby connecting the high pressure chamber 23 and the low pressure chamber 22. It has become possible to communicate with each other.

In this embodiment, a stop mechanism 27 is provided between the plunger 20 and the slider 8 as a mechanism for stopping the exhaust valve 3 when it lifts abnormally due to the above-mentioned cause.

This stop mechanism 27 has an outer surface of a part of the upper part of the plunger 20 having a small diameter, and a stepped part 20b formed between the outer surface of the upper part of the plunger 20 and a larger diameter part of the lower part, and further has a step part 20b formed between the outer surface of the plunger 20 and the inner surface of the cylinder 11. A fixture 30 is attached to the inner surface of the upper end of the slider 8 that fits into the gap between the
An example is shown in which a (snap spring) is provided.

The stop mechanism 27 is a means for preventing the exhaust valve 3 provided in the cylinder of the engine from lifting abnormally and maintaining the normal opening and closing operation when the exhaust valve 3 is opened and closed. This holding means means a member for regulating the relative movement distance between the plunger 20 and the slider 8 fitted on the outer surface thereof, and is not limited to the above-mentioned embodiment. It is also possible to use the format of

Next, the effect will be explained.

First, pressure oil is supplied from the pressure supply source into the high pressure chamber 23 of the hydraulic lifter 10, and all the valves 3 in the reduced cylinder section and other cylinder sections are supplied via the rocker arm 6.
When the exhaust brake butterfly valve 2 is closed in an all-cylinder operating state in which the exhaust brake is opened and closed, the exhaust brake valve 2 is switched to a reduced-cylinder operating state, and the pressure in the exhaust pipe 1a increases due to the pumping action of the engine. Then, an abnormal lift occurs in which the exhaust valve 3 is lifted into the cylinder by the exhaust pressure P on the cam base diameter 4.

When an abnormal lift of the exhaust valve 3 occurs in this way, one end of the rocker arm 6 that is in contact with the upper end of the valve stem 13 of the exhaust valve 3 moves downward.
At the same time, the slider 8 also descends via the bracket 7 that swingably supports the rocker arm 6.
Then, the pressure in the high pressure chamber 23 decreases by that amount, so the check ball 21 is pushed by the pressure oil into the low pressure chamber 22 and opens the valve, and the pressure oil in the low pressure chamber 22 is supplied into the high pressure chamber 23. It turns out.

Then, when the exhaust valve 3 opens, the internal pressure of the exhaust pipe 1a decreases, and the exhaust valve 3 rises due to the elastic force of the spring to close the valve hole.

When the bracket 7 abnormally descends as described above, the slider 8 fixed to the bracket 7 will descend by that amount, but in the present invention, the surface of the small diameter portion of the plunger 20 is The fixture 30 moves together with the plunger 8, and the fixture 30 comes into contact with the stepped portion 20b provided on the plunger 20, so that the slider 8 is stopped with respect to the plunger 20.

As a result, the lock arm shaft 12 stops the stop mechanism 2 at the position where the exhaust valve 3 is lifted within the allowable range.
It is fixed by 7. As a result, the rocker arm 6 is returned to the cam base dial 4, and the exhaust valve 3 opens and closes as in normal operation. Therefore, it is possible to prevent an accident in which the exhaust valve 3 hits the top surface of the piston.

FIG. 3 shows a technology related to the present invention, and in this example, the slider 8 has a discharge hole 27a.
(holding means, stopping mechanism) is provided, and the pressure oil filled in the high pressure chamber 23 is discharged through the opening thereof. This discharge hole 27a operates as a kind of valve, and when the discharge hole 27a is closed by the lower end 20c of the plunger 20, pressure oil is retained in the high pressure chamber 23. When the rocker arm 6 is removed from the lower end 20c, the pressure oil in the high pressure chamber 23 is discharged to the outside through the discharge hole 27a, and the range in which the rocker arm 6 is pushed down is restricted.

In this related technology, this discharge hole 27a
The lower end portion 20c of the plunger 20 corresponds to the stopping mechanism of the embodiment.

FIG. 4 shows a stop mechanism 27 that employs means for regulating the movement range of the check valve 31.

In this related technology, the orifice passage 20
A check valve 31 that closes the valve a is composed of a head 32 and a flange portion 34 connected via a rod 33, and the rod 33 and flange portion 34 are fixed to the bottom wall surface of the slider 8 as a stopper/guide member. 35, and a spring 25 is further interposed between the bottom wall surface of the slider 8 and the flange portion 34 to always bias the valve in the valve closing direction.

In this related technology, by setting the height of the stopper/guide member 35 to a constant height, the upward position of the check valve 31 is regulated, and when the exhaust valve 3 is abnormally lifted, the check valve 3
1 does not close the orifice passage 20a, thereby allowing the pressure oil in the high pressure chamber 23 to escape to the low pressure chamber 22 side.

Although the above-mentioned embodiments and related techniques are applied to the exhaust valve of a variable displacement engine equipped with an exhaust brake, they can also be applied to diesel engine vehicles and gasoline engine vehicles that do not use exhaust brakes. is possible, and it is also possible to use it for an intake valve.

[Effect of idea]

As described above, the valve stop device for an internal combustion engine according to the present invention has a cylinder that opens on the valve side and is fixed to the lower surface of the cylinder head, and is fixed concentrically inside the cylinder with a gap. a slider whose one end is fixed to a bracket that swingably supports the rocker arm and whose other end is fluid-tightly fitted into the gap, and a check valve that opens and closes an orifice passage formed in the plunger. The hydraulic lifter is configured to maintain a high pressure inside the slider, and a member is provided between the plunger and the slider for regulating the range of movement of the plunger and the slider that slides on the surface of the plunger. It is composed of

Therefore, even if an abnormal lift occurs on the cam base dial 4 of a valve (exhaust valve 3, etc.), the range of movement of the rocker arm 6 is limited, and the opening/closing operation of the valve can be maintained in a normal state. .

The effect of restricting the movement range of the rocker arm 6 prevents the exhaust valve from being held in an abnormally protruding state inside the cylinder, and prevents the valve from colliding with the top surface of the piston, thereby preventing valve damage. It is possible to prevent accidents such as this.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional variable displacement engine, Figure 2 is a sectional view of a hydraulic lifter according to an embodiment of this invention, and Figures 3 and 4 are sectional views of a hydraulic lifter related to this invention. It is. 3...Exhaust valve, 6...Rocker arm, 7...Bracket, 8...Slider, 9...Cylinder head, 10...Hydraulic lifter, 20...Plunger,
20a... Orifice passage, 20b... Stepped section, 2
1...Check ball, 22...Low pressure chamber, 23...
... Hyperbaric chamber, 27... Stopping mechanism, 30... Fixture.

Claims (1)

[Claims for Utility Model Registration] A cylinder fixed to the lower surface of the cylinder head and opened to the valve side, a plunger fixed concentrically to the inside of this cylinder with a gap, and a rocker arm that is swingably supported. The inside of the slider is maintained at high pressure by a slider having one end fixed to a bracket and the other end fluid-tightly fitted into the gap, and a check valve for opening and closing an orifice passage formed in the plunger. A valve stop device for an internal combustion engine, comprising a hydraulic lifter, and a member for regulating the movement range of the plunger and a slider that slides on the surface of the plunger.