JPH01134015A - Valve system for internal combustion engine - Google Patents

Abstract

PURPOSE:To maintain the quantity of working oil constant regardless of viscosity thereof by providing a hole forming member to be displaced axially corresponding to the viscosity of working oil to a cylinder body in a hydraulic drive mechanism for opening/closing a valve corresponding to the profile of a cam. CONSTITUTION:In a system where an intake valve 5 is opened/closed through a lifter 14 slidable with a cam 9 on a cam shaft 8 interlocked with a crankshaft, a hydraulic drive mechanism 10 for opening/closing the intake valve 5 corresponding to the profile of the cam 9 is arranged between the lifter 14 and the intake valve 5. The hydraulic drive mechanism 10 is provided with a valve side piston 13 and a cam side piston 15. A hole forming member 36 is screwed into a circular recess 33 made across upper and lower cylindrical bodies 25, 26 of the cylinder body 12 so as to define a damper chamber 39 and a working oil chamber 40 respectively between the hole forming member 36 and respective pistons 13, 15. The hole forming member can be displaced axially by driving a rack 57 and rotating the lower cylindrical body 26 through a gear 56.

Description

Detailed Description of the Invention A0 Object of the Invention (1) Industrial Field of Application The present invention provides an intake valve or an exhaust valve that is spring-biased in the valve closing direction. The other end of the piston is interlocked and connected, and one end of the cam-side piston is interlocked and connected to a cam driven by the crankshaft, and the other end of the cam-side piston communicates with the hydraulic oil chamber facing and opens into the damper chamber. A short cylindrical part protrudes from one end of the valve-side piston to form a small annular passage between the communicating hole and the inner surface of the communicating hole when the piston is inserted into the communicating hole. The present invention relates to a valve train for an internal combustion engine that includes a throttling mechanism that performs a throttling action only between the middle of the valve closing operation and the fully closed state.

(2) Prior Art Conventionally, such devices have been developed, for example, in Japanese Patent Publication No. 52-35813
It is known from the publication no.

(3) Problems to be Solved by the Invention By the way, this device uses a throttle mechanism to limit the flow rate of hydraulic oil returning from the damper chamber to the hydraulic oil chamber when the intake valve or exhaust valve is closed. Alternatively, the closing speed of the exhaust valve is slowed down to reduce the impact when seating, thereby preventing damage to the intake valve or exhaust valve. However, the viscosity of the hydraulic oil is not taken into account, and the operating speed of the valve-side piston changes due to changes in viscosity depending on the temperature of the hydraulic oil.

The present invention has been made in view of the above circumstances, and provides a valve train for an internal combustion engine that can adjust the operating speed of the valve-side piston to a constant value when the valve is closed, regardless of changes in the viscosity of the hydraulic oil. The purpose is to provide.

B2 Structure of the Invention (1) Means for Solving the Problems According to the present invention, the cylinder body into which the valve side piston is slidably fitted has a hole forming member that forms the communication hole.
The cylinder body is provided to be movable in the axial direction in order to change the axial position according to the viscosity of the hydraulic oil.

(2) Effect According to the above configuration, by changing the axial position of the hole forming member according to the viscosity of the hydraulic oil, the insertion length of the short cylindrical portion into the communication hole can be changed, and therefore the hydraulic oil can be inserted into the communication hole. Since the flow resistance in the throttle mechanism can be adjusted according to the viscosity of the oil, the flow rate of hydraulic oil from the damper chamber to the hydraulic oil chamber can be adjusted to a nearly constant value, and the movement speed of the valve side piston in the valve closing direction can be kept almost constant. can be adjusted to

(3) Embodiment Hereinafter, an embodiment of the present invention will be explained with reference to the drawings.First, in FIG. An intake valve port 2 that opens to the intake boat 3 is bored to communicate with the intake boat 3, and an intake valve 5 that can be seated on a ring-shaped valve seat member 4 fixed to the intake valve port 2 is connected to the intake valve port 2. It is guided so as to be able to move up and down by cylinder spatulas l-H to open and close. Moreover, the flange 6 provided at the upper end of the intake valve 5
A valve spring 7 is compressed between the valve spring 7 and the cylinder head H, and the spring force of the valve spring 7 biases the intake valve 5 upward, that is, in the valve closing direction.

On the other hand, a camshaft 8 rotatably driven by a crankshaft (not shown) is disposed above the cylinder head H, and a cam 9 provided on the camshaft 8 is disposed between the upper end of the intake valve 1. A hydraulic drive device 10 is disposed for driving the intake valve 1 to open and close using hydraulic pressure according to the profile of the cam 9.

In FIG. 2, the hydraulic drive device 10 is provided on a support portion 11 fixed to a cylinder head I.
A cylinder body 12 that extends vertically above the intake valve 5 and is fixed to the support portion 11; and a valve-side piston 13 that abuts the upper end of the intake valve 5 and is slidably fitted to the lower part of the cylinder body 12.
and a lifter 14 that slides into contact with the cam 9 of the camshaft 8.
A cam-side piston 15 is provided which is slidably fitted into the upper part of the cylinder body 12 with its upper end abutting the lifter 14.

The support part 11 is made up of an upper support part 16 and a lower support part 17 that are connected to each other, and the support part 11 is formed above the intake valve 5.
1 includes, in order from the top, a first hole 18 , a second hole 20 that has a smaller diameter than the first hole 18 and is connected to the lower end of the first hole 18 via a step 19 , and a second hole 18 . 20 and is connected to the lower end of the second hole 20 via the step 21; A fourth hole 24 continuous to the lower end of the portion 22
is bored and extends vertically coaxially with the intake valve 5.

The cylinder body 12 is formed by coaxially joining an upper cylinder body 25 and an upper cylinder body 26. The upper cylindrical body 25 is basically formed into a cylindrical shape with an outer diameter large enough to be inserted into the second hole 20, and a stepped portion is provided at the lower end of the upper cylindrical body 25 via a shim 27. An engagement collar 28 is provided that extends outward in the radial direction to engage with the engagement collar 21 .

Further, a male thread 29 is carved in a portion of the upper cylinder body 25 that protrudes above the second hole 20, and by tightening a nut 30 that is screwed into this male thread 29 until it abuts against the stepped portion 19, the upper cylinder body 25 is raised. The cylinder body 25 is fixed to the upper support part 16.

The upper cylinder body 26 is composed of a large diameter part 26a that fits into the third hole 22 and a small diameter part 26b that fits into the fourth hole 24, which are coaxially arranged together via a step 26c facing downward. Large diameter part 26a
The upper end surface is in sliding contact with the lower end of the upper cylinder body 25, that is, the end surface of engagement #2B via the seal member 31, and the step portion 26c is in contact with the third
It comes into sliding contact with the step 23 between the hole 23 and the fourth hole 24 . Thereby, with the upper support part 16 and the lower support part 17 mutually coupled, the upper cylinder body 26 is held between the lower end of the upper cylinder body 25 and the step part 23 so as to be rotatable around the axis. Furthermore, a sealing member 32 that slides into contact with the inner surface of the third hole 22 is fitted onto the outer surface of the large diameter portion 26a of the upper cylinder 26.

Referring also to FIG. 3, the upper cylinder body 25 of the cylinder body I2
An annular recess 33 is provided on the inner surface of the joint portion of the upper cylinder body 26 extending between the upper cylinder body 25 and the upper cylinder body 26, and a female thread 3
4 is engraved. Further, a protrusion 35 extending in the axial direction of the cylinder body 12 is provided in a protruding manner on the upper side surface of the annular recess 33 . A disk-shaped hole forming member 36 is screwed into the female screw 34, and an engaging groove 37 extending in the axial direction is bored in the side surface of the hole forming member 36 to engage the protrusion 35. Ru. Therefore, the hole forming member 36 is prevented from rotating about its axis, but is allowed to move in the axial direction within the annular recess 33. Further, a communicating hole 38 is coaxially formed in the center of the hole forming member 36.

The valve-side piston 13 defines a damper chamber 39 between it and the hole-forming member 3G, and is slidably fitted into the lower part of the cylinder body 12, and the cam-side piston 15 defines a damper chamber 39 between it and the hole-forming member 36. A hydraulic oil chamber 40 is defined in the cylinder body 11, and the cylinder body 11 is slidably fitted into the upper part of the cylinder body 11.

The valve side piston 3 is placed in the cylinder body 1 with the closed end facing upward.
The lower opening end of a sliding member 41 that is slidably fitted to the lower part of the intake valve 5 is closed by an abutting member 42 that abuts the upper end of the intake valve 5. Contact member 4
An oil chamber 43 is formed between the two. Moreover, the sliding member 4
A short cylindrical portion 44 that can be inserted into the communication hole 38 coaxially protrudes from the center of the upper end of 1, and the aperture mechanism 45 is constituted by this short cylindrical portion 44 and the communication hole 38.

The outer diameter of the short cylindrical portion 44 is set such that there is a gap of several tens to hundreds of μm between it and the inner surface of the communication hole 38.
As a result, when the short cylindrical part 44 is inserted into the communication hole 38, an annular micro passage 46 is formed between the short cylindrical part 44 and the communication hole 38, and this micro passage 46 connects the damper chamber 39 to the hydraulic oil chamber. Flow of hydraulic oil to 40 is restricted. Moreover, the micro passage 46 is formed only when the short cylindrical portion 44 is inserted into the communication hole 38, and the axial length of the short cylindrical portion 44 is limited to the length during the closing operation of the intake valve 5, that is, when the short cylindrical portion 44 is inserted into the communication hole 38. The valve side piston 13 is set to be inserted into the communication hole 38 while being pushed upward by the valve spring 7.

Furthermore, in the oil chamber 43 of the valve side piston 13, a short cylindrical portion 44 is provided.
A spherical valve body 47 that can close the opening end to the oil chamber 43 is housed, and the valve body 47 is biased in the valve closing direction by a spring 48 compressed between it and the abutting member 42 . Further, the sliding member 41 is provided with a through hole 49 that communicates the oil chamber 43 with the damper chamber 39 . With this configuration, the one-way valve 50 opens when the oil pressure in the short cylindrical part 44 is higher than that in the oil chamber 43 by a certain value and guides the hydraulic oil from the short cylindrical part 44 into the oil chamber 43.
The one-way valve 50 is configured such that when the short cylindrical portion 44 is inserted into the communication hole 38 and the hydraulic pressure in the hydraulic oil chamber 40 is increased, the hydraulic oil in the hydraulic oil chamber 40 is transferred to the oil chamber. 43 to the damper chamber 39.

Therefore, the throttle mechanism 45 is activated by the valve spring 7 when the short cylindrical portion 44 is below the communication hole 38, that is, when the intake valve 5 is pushed down to open the intake valve 5, and when the intake valve 5 is fully open. When the valve is partially closed by being pushed upward, no throttling action is performed, and the short cylindrical portion 44 is inserted into the communication hole 38 during the valve closing operation to close the intake valve 5.
The throttling action is performed only until the valve is fully closed.

The cam-side piston 15 is formed into a bottomed cylindrical shape with the closed end facing downward, and the upper open end of the cam-side piston 15 is closed by a closing member 51 that can come into contact with the lid 14 . Further, the lifter 14 is formed into a bottomed cylindrical shape so that the outer surface of the closed end is in sliding contact with the cam 9, and is slidably fitted into the first hole 18. Furthermore, an abutting protrusion 14 a that abuts against the closing member 51 of the cam-side piston 15 is protrudingly provided at the center of the inner surface of the closed end of the lifter 14 .

A storage chamber 52 is formed between the cam-side piston 15 and the closing member 51.
A through hole 53 that guides the hydraulic oil stored in the cam 9 to the sliding contact part with the cam 9.
is drilled. Moreover, at the closed end of the cam side piston 15,
An oil hole 54 that can communicate with the hydraulic oil chamber 40 is bored, and a check valve 55 that only allows the hydraulic oil to flow from the storage chamber 52 to the hydraulic oil chamber 40 side is provided.

A gear 56 is engraved on the lower outer surface of the large diameter portion 26a of the lower body 26 in the cylinder body 12, and a rack 57 that is movable in the axial direction and supported by the support portion 11 is attached to the gear 56.
6 is engaged. Moreover, this rack 57 is connected to a drive means (not shown), and the drive means rotates the lower body 26 in a direction that moves the hole forming member 36 upward when the temperature of the hydraulic oil is low and the viscosity of the hydraulic oil is high. When the temperature of the hydraulic oil is high and the viscosity of the hydraulic oil is low, the lower body 26 is rotationally driven in a direction to move the hole forming member 36 downward.

Next, the operation of this embodiment will be explained. When the intake valve 5 is fully closed, the hydraulic drive device 10 is in the state shown in FIG. 2, and from this state shown in FIG. Can be lowered. The cam-side piston 15 is pushed downward by the lifter 14, the volume of the hydraulic oil chamber 40 is reduced, and the hydraulic oil in the hydraulic oil chamber 40 is introduced into the damper chamber 39 through the one-way valve 50. As a result, the valve-side piston 13 is pushed downward, and the intake valve 5 is driven to open against the spring force of the valve spring 7.

After the intake valve 5 is fully open, when the pressing force of the cam 9 on the lifter 14 is released, the intake valve 5 is driven upward by the spring force of the valve spring 7, that is, in the valve closing direction. Due to this valve closing operation of the intake valve 5, the valve side piston 13 is also pushed upward, and the hydraulic oil in the damper chamber 39 is returned to the hydraulic oil chamber 40 through the communication hole 38. 44 is inserted into the communication hole 38, the throttling action by the throttling mechanism 45 is started, and the hydraulic fluid chamber 4 is drawn from the damper chamber 39.
The flow of hydraulic fluid to 0 is restricted. For this reason, the intake valve 5
The upward movement speed, that is, the valve closing speed is slowed midway through the valve closing operation, and the intake valve 5 is gently seated on the valve seat member 4. Therefore, the impact upon seating is alleviated, and damage to the intake valve 5, valve seat member 4, etc. can be prevented as much as possible.

By the way, the amount of hydraulic oil flow restricted by the throttle mechanism 45 is as follows:
The viscosity of the hydraulic oil varies depending on the temperature of the hydraulic oil, and when the temperature of the hydraulic oil is high, that is, the viscosity is low, the amount of hydraulic oil returned from the damper chamber 39 to the hydraulic oil chamber 40 is relatively large, and the temperature of the hydraulic oil is low. When the viscosity is low, that is, when the viscosity is high, the amount of hydraulic oil that returns from the damper chamber 39 to the hydraulic oil chamber 40 is relatively small. If the amount of hydraulic oil returned from the damper chamber 39 to the hydraulic oil chamber 40 differs in this way, the valve closing speed of the valve-side piston 13 will change. Therefore, the axial position of the hole forming member 36 is changed depending on the viscosity of the hydraulic oil. In other words, when the temperature of the hydraulic oil is low and the viscosity is high, the throttle mechanism 45
In order to reduce the flow resistance, the hole forming member 36 is moved upward to shorten the insertion length of the short cylindrical portion 44 into the communication hole 38, and when the temperature of the hydraulic oil is high and the viscosity is low, the flow resistance is reduced. In order to increase the hole size, the hole forming member 36 is moved downward to lengthen the insertion length of the short cylindrical portion 44 into the communication hole 38.

In this way, the amount of hydraulic oil returned from the damper chamber 39 to the hydraulic oil chamber 40 can be adjusted to be almost constant regardless of the viscosity of the hydraulic oil, and the valve side piston 13 and the cam side piston 15
The moving speed on the valve closing side can be made almost constant regardless of the viscosity of the hydraulic oil.

In the above embodiment, the valve operating system for the intake valve 5 has been described, but the present invention can be implemented similarly for the valve operating system for the exhaust valve.

C9 Effects of the Invention As described above, according to the present invention, the cylinder body into which the valve-side piston is slidably fitted has a hole-forming member that forms the communication hole, and the hole-forming member that forms the communication hole has an axis that corresponds to the viscosity of the hydraulic oil. Since the cylinder body is movable in the axial direction to change the directional position, by changing the insertion length of the short cylindrical part into the communication hole and adjusting the flow resistance, it is possible to move from the damper chamber to the hydraulic oil chamber. The amount of hydraulic oil that returns can be made substantially constant regardless of the viscosity of the hydraulic oil, and therefore the operating speed at the time of valve closing can be prevented from varying depending on the viscosity of the hydraulic oil.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an overall longitudinal sectional side view, FIG. 2 is an enlarged longitudinal sectional view of a hydraulic drive device,
FIG. 3 is an enlarged sectional view taken along the line ■--■ in FIG. 2.

Claims (1)

[Claims] An intake valve or an exhaust valve that is spring-biased in the valve-closing direction has a
One end of the valve-side piston faces the damper chamber, and the other end of the valve-side piston is linked.
One end of the cam-side piston is interlocked and connected to the cam, which is connected and driven by the crankshaft, and has a communication hole that communicates with the hydraulic oil chamber facing the other end of the cam-side piston and opens into the damper chamber, and a communication hole. A short cylindrical part protrudes from one end of the valve-side piston to form a small annular passage between the inner surface of the communication hole and the inner surface of the communication hole when the valve is inserted into the valve. In a valve train for an internal combustion engine that includes a throttling mechanism that performs a throttling action only when the valve is closed,
The cylinder body into which the valve side piston is slidably fitted includes:
A valve train for an internal combustion engine, wherein the hole forming member forming the communication hole is provided so as to be movable in the axial direction of the cylinder body so as to change the axial position in accordance with the viscosity of the hydraulic oil.