JPH0726923A - Valve control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To define a damper chamber for lowering the on-coming speed of a valve plunger, when the valve plunger precisely return to a predetermined position. CONSTITUTION:A cylinder member 18 is slidably located in a slide hole 5c in a block 5, and is formed therein with a cylinder hole 19 in which a valve plunger 20 is slidably fitted. A damper chamber 21 is defined between the inner peripheral surface of the cylinder hole 19 and the outer peripheral surface of the valve plunger 20. A hydraulic chamber 24 confronting the cylinder member is defined in the bottom part of the slidable hole 5c. Pressure oil is filled in the hydraulic chamber 24, being fed from a pump 12 by way of a check valve 26. Further, the cylinder member is pushed out by the pressure oil in the on-coming direction of the valve plunger 20 which accordingly bumps upon the bottom surface of the cylinder hole 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve control device for an internal combustion engine which controls a lift amount of an intake valve or an exhaust valve (simply referred to as a valve in this specification) of the internal combustion engine.

[0002]

2. Description of the Related Art Generally, a control device of this type includes a cam plunger that reciprocates following a cam that is rotationally driven by an engine, a valve plunger that interlocks with the cam plunger via hydraulic oil, and a cam plunger. Hydraulic oil release valve (hydraulic oil release means) that releases hydraulic oil to the low pressure side during forward movement
When the valve plunger moves forward in conjunction with the forward movement of the cam plunger, the valve lifts from the valve seat against the biasing force of the valve spring. On the other hand, when the hydraulic release valve is opened during the forward movement of the cam plunger to release the hydraulic oil to the low pressure side, the pressure of the hydraulic oil decreases, the valve plunger and valve are moved back by the valve spring, and the valve seat Is supposed to sit down.

When the valve is seated on the valve seat at high speed by the urging force of the valve spring, noise is generated due to the impact when seated. Therefore, when the valve plunger moves back to a predetermined position inside the cylinder hole into which the valve plunger slidably fits, a damper chamber defined by the valve plunger is provided, and the hydraulic oil in this damper chamber causes resistance such as throttling. By the buffering action based on the resistance when passing through the section, the return speed of the valve plunger and valve is reduced,
A valve control device has been proposed that reduces noise caused by valve seating (see Japanese Utility Model Laid-Open No. 3-99806).

When the return velocity of the valve plunger and the valve is reduced by forming the damper chamber in this way, the velocity reduction starts when the valve plunger returns to a certain position. There is a need. If the damper chamber is formed and the speed starts decreasing before the valve plunger moves back to a predetermined position, the valve seating timing will be delayed. On the other hand, if the speed decreases after the valve plunger exceeds the predetermined position, the valve will sit on the valve seat before the speed is sufficiently decreased, and the impact noise cannot be reduced.

However, the returning position at which the valve plunger forms the damper chamber is affected not only by the valve plunger length accuracy, but also by the valve length accuracy, the valve seat position accuracy, and the like. Therefore, it is difficult to form the damper chamber at a fixed position.

Therefore, in the conventional valve control device,
A shim is interposed between the valve and the valve plunger, and the thickness of the shim is appropriately adjusted so that the damper chamber is formed when the valve plunger returns to a predetermined position.

[0007]

However, the shim adjustment requires a great deal of time and effort. In particular, a recent internal combustion engine has a large number of cylinders, and each cylinder is provided with a large number of valves, so that shim adjustment is a very troublesome work.

The present invention has been made to solve the above problems, and a valve control device for an internal combustion engine in which a damper chamber is formed when the valve plunger is accurately returned to a predetermined position without adjusting the shim. The purpose is to provide.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a cam plunger which reciprocates following the rotation of a cam, and a forward movement which is interlocked with the cam plunger via hydraulic oil. A valve plunger for opening the valve at times, and a hydraulic oil releasing means for releasing the hydraulic oil to the low pressure side when the cam plunger moves forward, and between the valve plunger and a cylinder hole into which the valve plunger is slidably fitted. In a valve control device for an internal combustion engine in which a damper chamber is formed to reduce the backward moving speed of the valve plunger when the valve plunger returns to a predetermined position. The tip has a reference surface so that it can be displaced relative to the valve plunger, and there is a pressure oil chamber to which pressure oil is supplied from a pressure oil supply source via a check valve. A pressing mechanism is provided which relatively displaces the reference surface portion in the forward movement direction of the valve plunger by pressure oil supplied to the chamber and abuts against the tip end portion in the backward movement direction of the valve plunger. Is.

[0010]

The return position of the valve plunger when the damper chamber starts to be formed is determined based on the reference surface portion, and is not affected by the valve length accuracy, valve seat size and position accuracy. Therefore, the backward movement position of the valve plunger for forming the damper chamber can be made substantially constant.

[0011]

Embodiments of the present invention will now be described with reference to FIGS.
Will be described with reference to. 1 to 4 show an embodiment of the present invention, in which a cylinder head 1 of an engine is provided with a valve 2 which is vertically movable. This valve 2 is biased upward by a valve spring 3,
As a result, the valve seat 4 is seated.

A block 5 is provided on the upper surface of the cylinder head 1.
Is fixed. An oil chamber forming hole 5a extending downward from the upper surface is formed in the block 5, and a housing hole 5b and a sliding hole 5c whose axis is aligned with the axis of the valve 2 are sequentially arranged upward from the lower surface. Has been formed. The upper end of the valve 2 and the valve spring 3 are housed in the housing hole 5b.

A sleeve 6 is rotatably and positionally fixed in the oil chamber forming hole 5a. A cam plunger 7 is slidably inserted in the sleeve 6. The cam plunger 7 is pressed and brought into contact with the cam 10a of the cam shaft 10 by the return spring 8 via the tappet 9 and reciprocates (moves up and down) following the rotation of the cam 10a. The camshaft 10 is driven to rotate by the engine.

A sleeve 6 is provided at the lower end of the oil chamber forming hole 5a.
An oil chamber 11 defined by the cam plunger 7 is formed. The oil chamber 11 is filled with hydraulic oil supplied from the pump 12 via the check valves 13 and 14, and the hydraulic oil is pressurized by the forward movement (downward movement) of the cam plunger 7. When the hydraulic oil is pressurized, the valve plunger 20 described later moves forward, and the valve 2 lifts from the valve seat 4.

In order to control the lift amount of the valve 2, a hydraulic oil releasing mechanism (a hydraulic oil releasing means) 15 is provided between the sleeve 6 and the cam plunger 7. That is, as shown in FIGS. 3 and 4, a gear portion 6a is formed on the outer periphery of the lower end portion of the sleeve 6. This gear part 6
"a" meshes with a rack 16 movably provided in the block 5, and the sleeve 6 is rotationally displaced by appropriately moving the rack 16. Further, the sleeve 6 has a control hole 6b penetrating its peripheral wall portion.
Are formed. An inclined surface 6c is formed in the control hole 6b. Further, as shown in FIG. 1, the control hole 6b
Is connected to the accumulator 17 (low pressure side).
The accumulator 17 has two check valves 13 and 14
It is also connected between.

On the other hand, the cam plunger 7 is formed with a hole 7a extending upward from the lower end surface facing the oil chamber 11 and a relief hole 7b extending from the outer peripheral surface to the inner peripheral surface of the hole 7a. There is. The escape hole 7b may face the control hole 6b during the forward movement of the cam plunger 7, or may not face it at all. This is a sleeve 6
It depends on the rotation position of the. The escape hole 7b is the control hole 6b
When facing the control hole 6b, the escape hole 7b crosses the inclined surface 6c and faces the control hole 6b. Therefore, when the sleeve 6 is rotationally displaced by the rack 16, the escape hole 7
When b is opposed to the control hole 6b, in other words, the relief hole 7
The forward position of the cam plunger 7 when b and the control hole 6b face each other can be changed. The rack 16 is
The position is controlled by a computer based on the operating condition of the engine.

As shown in FIG. 1, in the sliding hole 5c,
The cylinder member 18 is slidably inserted. At the lower end of the cylinder member 18, a cylinder hole 19 extending upward from the lower end surface is formed. The cylinder hole 19 includes a large diameter hole 19a on the lower end side and a small diameter hole 1 on the upper end side.
9b and. The small diameter hole 19b communicates with the oil chamber 11 via a hole 18a formed in the cylinder member 18.

Large diameter hole 19a and small hole 19 of cylinder hole 19
The large diameter portion 20a and the small diameter portion 20b of the valve plunger 20 are slidably fitted in b. The lower surface of the valve plunger 20 abuts the upper surface of the valve 2 via a shim 30, and the valve plunger 20 reciprocates in conjunction with the valve 2. Also, as shown in FIG.
The large-diameter portion 20a is always fitted in the large-diameter hole 19a, but the small-diameter portion 20b has the valve plunger 20 above the predetermined position as shown in FIGS. 2 (B), (C), and (D). When it is located, it fits into the small diameter hole 19b, and when it is located below the predetermined position, it comes out of the small diameter hole 19b. When the valve 2 is seated, the upper end surface of the small diameter portion 20b abuts the bottom surface 19c of the small diameter hole 19b. This point will be described later.

When the small diameter portion 20b is fitted into the small diameter hole 19b, an annular damper chamber 21 surrounded by the inner peripheral surface of the large diameter hole 19a and the outer peripheral surface of the small diameter portion 20b is formed. The damper chamber 21 communicates with the small diameter hole 19b through the hole 20c formed in the valve plunger 20, the oil sump chamber 20d and the hole 20e, and further through the hole 18a.
It communicates with 1. Therefore, when the hydraulic oil is pressurized by the forward movement of the cam plunger 7, the hydraulic oil flows into the damper chamber 21.

A check valve 22 is arranged in the oil sump chamber 20d to prevent the hydraulic oil from flowing out from the damper chamber 21 side to the hole 20e side. On the other hand, a hole 20f having an unillustrated orifice is provided between the damper chamber 21 and the hole 20e. Therefore, FIG.
When the base end portion of the small diameter portion 20b is fitted in the small diameter hole 19b, the hydraulic oil flows from the damper chamber 21 to the hole 20e side only through the hole 20f having the orifice as shown in FIG.

Further, a tapered portion 20g is formed at the tip of the small diameter portion 20b of the valve plunger 20. Therefore, when the damper chamber 21 is formed by the backward movement of the valve plunger 20, not only the hydraulic oil in the damper chamber 21 flows out to the small diameter hole 19b through the orifice, but also the outer peripheral surface of the taper portion 20g and the small diameter portion 19b. It will flow out to the small diameter hole 19b through the gap between the inner peripheral surface.

Further, the cylinder member 18 is pressed downward by the pressing mechanism 23, so that when the valve 2 is seated, the bottom surface 19c of the small diameter hole 19b has a small diameter portion 2a.
It is designed to hit the upper end surface of 0b. That is, the cylinder member 18 defines the pressure oil chamber 24 at the upper end of the sliding hole 5c. This pressure oil chamber 24
Is connected to the pump 12 via a throttle 25 and a check valve 26 for smoothing the pulsation thereof, and the cylinder member 18 is pressed downward by the pressure of the hydraulic oil supplied from the pump 12 to the pressure oil chamber 24. Has been done.

The upper end of the pressure oil chamber 24 is connected to the air vent mechanism 28 through the hole 27. This air vent mechanism 2
8 is a storage hole 28 communicating with the pressure oil chamber 24 through the hole 27.
a and a steel ball 28b inserted into the storage hole 28a. The hydraulic oil is prevented from flowing between the steel ball 28b and the storage hole 28a, but air is allowed to flow. The gap is formed. Therefore, the air contained in the hydraulic oil is discharged to the outside through the gap between the storage hole 28a and the steel ball 28b and does not accumulate in the pressure oil chamber 24. The steel ball 28b is fixed to the storage hole 28a by a bolt 29 having a groove 29a that allows air to pass therethrough.

Next, the operation of the valve control device for an internal combustion engine having the above structure will be described. When the cam shaft 10 is rotationally driven in synchronization with the rotation of the engine, the cam plunger 7 reciprocates following the rotation of the cam 10a. Cam plunger 7
Pressurizes the hydraulic oil in the oil chamber 11 during the forward movement. The pressurized hydraulic oil flows into the small diameter hole 19b of the cylinder hole 19 and presses the upper end surface of the small diameter portion 20b of the valve plunger 20 downward, and also through the hole 20e, the oil sump chamber 20d, and the hole 20c. It flows into the chamber 21 and presses the upper end surface of the large diameter portion 20a of the valve plunger 20 downward. This pressing force causes the valve plunger 20 to move forward, whereby the valve 2 is lifted from the valve seat 4 against the biasing force of the valve spring 3.

Relief hole 7b when the cam plunger 7 moves forward
Is not opposed to the control hole 6b, the cam plunger 7
Valve 2 and valve plunger 2
0 is moved back (returned) to the valve seat 4 side by the urging force of the valve spring 3, and the valve 2 is seated on the valve seat 4. Note that the lift amount of the valve 2 at this time becomes a predetermined maximum lift amount.

On the other hand, when the escape hole 7b faces the control hole 6b during the forward movement of the cam plunger 7, the escape hole 7 is formed.
When b is opposed to the control hole 6b, the hydraulic oil in the oil chamber 11 flows out to the accumulator 17 (low pressure side), and the cam plunger 7
The substantial pressurization of the hydraulic oil by is completed. Therefore,
The valve 2 and the valve plunger 20 will return during the forward movement of the cam plunger 7, so that the valve 2
The lift amount of is determined by the time when the relief hole 7b and the control hole 6b face each other. Therefore, the lift amount of the valve 2 can be adjusted by rotationally displacing the sleeve 6 to change the facing time of the escape hole 7b and the control hole 6b.

During the backward movement of the valve plunger 20, the small diameter portion 20b thereof has a small diameter hole 19b of the cylinder hole 19.
The damper chamber 21 is formed by fitting to. Then, the backward movement speed of the valve plunger 20 is reduced due to the resistance of the hydraulic oil in the damper chamber 21 passing through the orifice.

However, in this embodiment, the small diameter portion 2
Since the taper portion 20g is formed at the tip of 0b,
As shown in FIG. 2B, the small diameter hole 19b of the small diameter portion 20b.
Initially, the outer peripheral surface of the small diameter portion 20b and the small diameter hole 1
A gap is formed between the inner peripheral surface of 9b and the working oil in the damper chamber 21 also flows out to the low pressure side through the small diameter hole 19b. Therefore, the valve plunger 20 is not slowed down abruptly, but is slowed down relatively slowly at the beginning. Then, as shown in FIG. 2C, when the base end portion of the small diameter portion 20b is fitted into the small diameter hole 19b, the hydraulic oil in the damper chamber 21 flows out only from the hole 20f having the orifice. The valve plunger 20 is greatly slowed down.

Here, in this valve control device,
Since the cylinder member 18 is made movable in the reciprocating direction of the valve plunger 20 and the cylinder member 18 is pressed downward by the hydraulic oil (pressure oil) supplied into the pressure oil chamber 24, the valve plunger 20 has a predetermined size. The small-diameter portion 20b can be fitted into the small-diameter hole 19b when it accurately returns to the position.

That is, assuming that the cylinder member 18 is fixed in position, the position of the valve plunger 20 when the small diameter portion 20b is fitted into the small diameter hole 19b changes depending on the dimensional accuracy of the cylinder member 18 and the valve plunger 20. Not only the dimensional accuracy of the valve 2 and the valve seat 4
Will vary depending on the position and dimensional accuracy.

In this respect, the cylinder member 18 is made movable as in this valve control device.
2 is pressed downward by the hydraulic oil introduced into the pressure oil chamber 24, when the valve 2 is seated, the bottom surface (reference surface portion) 19c of the small diameter hole 19b has the small diameter portion 20b as shown in FIG. 2D. The cylinder member 18 moves so as to hit the upper end surface.

Under such circumstances, the valve plunger 2 when the small diameter portion 20b starts to be fitted into the small diameter hole 19b.
It is only the depth dimensional accuracy of the small diameter hole 19b that affects the backward movement position of 0, and other dimensional accuracy such as the length of the valve 2 does not affect at all. Therefore, the backward movement position of the valve plunger when the small diameter portion 20b and the small diameter hole 19b start to be fitted can be made substantially constant without adjusting the shim. Therefore, it is possible to reliably prevent the valve 2 from sitting on the valve seat 4 and generating noise while the seating of the valve 2 is delayed or the speed is not sufficiently reduced.

When pressurized hydraulic oil is supplied to the small diameter hole 19b and the damper chamber 21 during forward movement of the cam plunger 7, the hydraulic oil presses the cylinder member 18 upward, but the pressurized oil chamber 24 Since the check valve 26 is provided in the cylinder, the cylinder member 18 is not moved upward.

Next, another embodiment of the present invention shown in FIG. 5 will be described. The embodiment shown in FIG. 5 differs from the above embodiment in that the cylinder member 18 is fixed while the valve plunger 20 is displaced with respect to the cylinder member 18 and abuts against the bottom surface 19c of the small diameter hole 19b serving as the reference surface portion. That is the point.

That is, a pressing mechanism 31 is provided at the lower end of the valve plunger 20. This pressing mechanism 3
1 has a recess 20h formed in the lower end surface of the valve plunger 20. The recess 20h communicates with the oil sump chamber 20d through the hole 20i and the check valve 32, and the piston 33 is slidably fitted in the recess 20i. By fitting the piston 33 into the recess 20i, the pressure oil chamber 34 is formed in the recess 20i. The piston 33 is in contact with the valve 2.

In this embodiment, when the valve 2 is seated, the hydraulic oil supplied from the pump 12 to the pressure oil chamber 34 pushes the piston 33 downward while pushing the valve plunger 20 upward. As a result, the tip surface of the small diameter portion 20b of the valve plunger 20 is abutted against the bottom surface (reference surface portion) 19c of the small diameter hole 19b of the cylinder hole 19. Therefore, similar to the above-described embodiment, when the valve plunger 20 returns to the predetermined position, the small diameter portion 20b is released.
Can be fitted into the small diameter hole 19b.

The present invention is not limited to the above embodiments, but can be modified as appropriate without departing from the scope of the invention. For example, in the above example,
A control hole 6b is formed in the sleeve 6, a relief hole 7b is formed in the cam plunger 7, and the relief hole 7b and the control hole 6b are opposed to each other to release hydraulic oil to the low pressure side (accumulator 17). The release timing is adjusted by rotationally displacing the sleeve 6 to change the facing timing between the escape hole 7b and the control hole 6b.
Is installed between the accumulator 17 and the accumulator 17, the operating oil is released to the low pressure side by opening the opening valve, and the opening timing of the operating oil release valve is appropriately set according to the operating state of the period. By changing it, the release timing of the hydraulic oil to the low pressure side may be adjusted.

Further, although the orifice is provided in order to create a buffering action when the hydraulic oil in the damper chamber 21 flows out to the low pressure side, a throttle may be provided. However, when the orifice is used, it is not affected by the viscosity of the hydraulic oil, so that even if the temperature of the hydraulic oil changes and its viscosity changes, a substantially constant buffering action can be obtained.

The pump 12 for supplying the hydraulic oil to the oil chamber 11 is also used as the pressure oil supply source for supplying the pressure oil to the pressure oil chamber 24 (34). Of course, other pumps or the like may be used.

[0040]

As described above, according to the valve control device for an internal combustion engine of the present invention, the reference surface portion formed in the cylinder hole is relatively moved by the pressing mechanism so that the reference surface portion of the valve plunger moves toward the tip end surface in the backward movement direction. Since they are abutted against each other, the return position of the valve plunger when the damper chamber is formed can be set to a constant position. Therefore, it is possible to prevent the seating of the valve from being delayed, or to prevent the seating on the valve seat from generating noise before the speed of the valve is sufficiently reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a small diameter portion and a small diameter hole of a cylinder hole when the valve plunger is returned.
FIG. 2A is a diagram showing a state before the small diameter portion is fitted in the small diameter hole, and FIG. 2B is a diagram showing a state in which a tip portion (tapered portion) of the small diameter portion is fitted in the small diameter hole. FIG. 2C is a diagram showing a state where the base end portion of the small diameter portion has started to be fitted into the small diameter hole, and FIG. 2D is a diagram showing a state when the return movement of the valve plunger is completed (when the valve is seated).

FIG. 3 is a sectional view taken along line XX of FIG.

FIG. 4 is a perspective view showing a sleeve, a cam plunger, and a rack.

FIG. 5 is a cross-sectional view showing the main parts of another embodiment of the present invention.

[Explanation of symbols]

 2 valve 4 valve seat 6 sleeve 7 cam plunger 10a cam 12 pump (pressure oil supply source) 15 hydraulic oil releasing means 17 accumulator (low pressure side) 18 cylinder member 19 cylinder hole 19a large diameter hole 19b small diameter hole 20 valve plunger 20a large diameter Part 20b Small diameter part 21 Damper chamber 23 Pressing mechanism 24 Pressure oil chamber 26 Check valve 31 Pressing mechanism 32 Check valve 34 Pressure oil chamber

Claims (1)

[Claims] 1. A cam plunger that reciprocates following the rotation of a cam, and a valve plunger that is interlocked with this cam plunger via hydraulic oil and that opens a valve when moving forward.
A hydraulic oil releasing means for releasing the hydraulic oil to the low pressure side when the cam plunger moves forward is provided, and the valve plunger is up to a predetermined position between the valve plunger and the cylinder hole into which the hydraulic oil is slidably fitted. In a valve control device for an internal combustion engine in which a damper chamber is formed to reduce the returning speed of the valve plunger when returning, in a returning direction of the valve plunger, a reference surface portion is provided at a tip end portion of the cylinder hole with respect to the valve plunger. Has a pressure oil chamber in which pressure oil is supplied from a pressure oil supply source via a check valve, and the reference surface portion of the valve plunger is moved by the pressure oil supplied to the pressure oil chamber. A valve control device for an internal combustion engine, comprising a pressing mechanism that is relatively displaced in a forward direction and abuts against a tip end portion in a backward direction of the valve plunger.