JPH01134016A - Valve system for internal combustion engine - Google Patents

Abstract

PURPOSE:To eliminate fluctuation of close valve speed, in a system where a hydraulic drive mechanism having a cam side piston and a valve side piston is arranged between a cam and an intake (exhaust) valve, by providing a heater for heating working oil such that the viscosity thereof is maintained approximately constant. 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 fitted to the lower and upper sections of a cylinder body 12. A throttle mechanism 41 for limiting flow of oil from a damper chamber 35 to a working oil chamber 36 is provided between them. A ring heater 25 is bonded to the central section of a wall partitioning the interior of the cylinder body 12 vertically into two in order to maintain viscosity of working oil approximately constant.

Description

[Detailed Description of the Invention] A1 Object of the Invention (1) Industrial Application Field The present invention provides an intake valve or an exhaust valve which is spring-biased in the valve closing direction, and has a valve side with one end facing a damper chamber. 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 a crankshaft, and there is a space between the hydraulic oil chamber, which the other end of the cam side piston faces, and the damper chamber. The present invention relates to a valve train for an internal combustion engine that is provided with a throttle mechanism that restricts the flow of hydraulic oil from a damper chamber to a hydraulic oil chamber.

(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 flow rate control 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. This is to slow down the closing speed of the valve or exhaust valve, reduce the impact when seating, and prevent damage to the intake or exhaust valve. Therefore, the operating speed of the valve-side piston changes due to a change 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 in which the viscosity of hydraulic oil is kept almost constant at all times and the operating speed when the valve is closed can be adjusted to a constant value. With the goal.

B1 Structure of the Invention (1) Means for Solving Problems The device of the present invention includes a heater for heating the hydraulic oil so as to keep the viscosity of the hydraulic oil substantially constant at all times.

(2) Effect According to the above configuration, the temperature of the hydraulic oil can be heated to a substantially constant temperature by the heater to prevent changes in viscosity. The moving speed of the side piston in the valve closing direction can be adjusted to be substantially constant.

(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 by the cylinder head H to be able to move up and down in order to open and close it. Moreover, a valve spring 7 is compressed between the flange 6 provided at the upper end of the intake valve 5 and the cylinder head H, and the spring force of the valve spring 7 causes the intake valve 5 to move upward, that is, to close. spring biased toward the 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 installed on a support part 11 fixed to the cylinder head H, and includes a cylinder body 12 that extends vertically above the intake valve 5 and is fixed to the support part 11. , a valve-side piston 13 that comes into contact with the upper end of the intake valve 5 and is slidably fitted into the lower part of the cylinder body 12; a lifter 14 that comes into sliding contact with the cam 9 of the camshaft 8; and an upper end that comes into contact with the lifter 14. The cam-side piston 15 is slidably fitted to the upper part of the cylinder body 12 in contact with the cylinder body 12.

Above the intake valve 5, the support part 11 has a first
A hole 18 , a second hole 20 that is smaller in diameter than the first hole 18 and continues to the lower end of the first hole 18 via a step 19 , and a second hole 20 that is larger in diameter than the second hole 20 and is stepped. A third hole 22 is connected to the lower end of the second hole 20 via the portion 21 and extends vertically coaxially with the intake valve 5 .

The cylinder body 12 has a small diameter portion 12a large enough to be inserted into the second hole 20 and a large diameter portion 12b large enough to fit into the third hole 22 coaxially through an upwardly facing stepped portion 12c. They are arranged in a row and basically formed into a cylindrical shape. The large diameter part 12b of the cylinder body 12 is inserted into the third hole by inserting the small diameter part 12a into the second hole 2o with a shim 27 interposed between the step part 12c and the step part 21. 22.

Moreover, a male thread 29 is carved in a portion of the small diameter portion 12a that protrudes upward from the second hole portion 2o.
The cylinder body 12 is fixed to the support part 11 by tightening the nut 30 screwed into the cylinder body 9 until it abuts against the step part 19. Further, an annular seal member 31 is fitted onto the outer surface of the large diameter portion 12b of the cylinder body 12 to achieve a seal between the large diameter portion 12b and the inner surface of the third hole portion 22.

A partition wall 32 is provided in the middle of the cylinder body 12 to partition the inside of the cylinder 12 into a lower cylinder hole 33 and an upper cylinder hole 34. The cam-side piston 15 defines a damper chamber 35 and is slidably fitted into the lower cylinder hole 33, and the cam-side piston 15 defines a hydraulic oil chamber 36 between the partition wall 32 and the upper cylinder hole 34. is slidably fitted to. Also, partition wall 3
A ring-shaped heater 25 is fixed to the center of the damper 2, and this heater 25 forms a communication hole 26 through which the damper chamber 35 and the hydraulic oil chamber 36 can communicate with each other.

The valve side piston 13 includes a contact member 38 that brings the lower open end of the sliding member 37, which is slidably fitted into the lower cylinder hole 33 with the closed end upward, into contact with the upper end of the intake valve 5. An oil chamber 39 is formed between the sliding member 37 and the abutting member 38.
A short cylindrical portion 40 that can be inserted into the communication hole 26 is coaxially protruded from the center of the upper end, and the short cylindrical portion 40 and the communication hole 26 constitute an aperture mechanism 41.

In FIG. 3, the outer diameter of the short cylindrical portion 40 is set so that there is a gap of several tens to hundreds of μm between the short cylindrical portion 40 and the inner surface of the communication hole 26.
When inserted into the damper chamber 35, an annular micro passage 42 is formed between the short cylindrical portion 40 and the communication hole 26, and this micro passage 42 restricts the flow of hydraulic oil from the damper chamber 35 to the hydraulic oil chamber 36. be done. Moreover, the micro passage 42 is formed only when the short cylindrical portion 40 is inserted into the communication hole 26, and the axial length of the short cylindrical portion 40 is limited to the length of the short cylindrical portion 40 during the closing operation of the intake valve 5, that is, on the valve side. The piston 13 is set to be inserted into the communication hole 26 while being pushed upward by the valve spring 7.

A spherical valve body 43 that can close the opening end of the short cylindrical portion 40 to the oil chamber 39 is housed in the oil chamber 39 of the valve-side piston I3. It is biased in the valve closing direction by a spring 44 that is compressed therebetween. Further, the sliding member 37 is provided with a through hole 45 that communicates the oil chamber 39' with the damper chamber 35. With this configuration, the one-way valve 46 opens when the oil pressure in the short cylindrical part 40 is higher than that in the oil chamber 39 by a certain value and guides the hydraulic oil from the short cylindrical part 40 into the oil chamber 39.
When the short cylindrical portion 40 is inserted into the communication hole 26 and the hydraulic pressure in the hydraulic oil chamber 36 is increased, the one-way valve 46 drains the hydraulic oil in the hydraulic oil chamber 36 into the oil chamber. 39 to the damper chamber 35.

Therefore, the throttle mechanism 41 is activated by the valve spring 7 when the short cylindrical portion 40 is below the communication hole 26, that is, when the intake valve 5 is pressed down to open the intake valve 5, and when the intake valve 5 is fully open. When the valve is partially closed due to being pushed upward, no throttling action is performed, and the short cylindrical portion 40 is inserted into the communication hole 26 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 47 that can come into contact with the lid 14 . Further, the lifter 1-4 is formed into a cylindrical shape with a bottom so that the outer surface of the closed end thereof slides into contact with the cam 9.1. It is slidably fitted into the first hole 18 . Moreover, lifter 14
A contact protrusion 14a that comes into contact with the closing member 47 of the cam-side piston 15 projects from the center of the inner surface of the closed end.

A storage chamber 48 is formed between the cam-side piston 15 and the closing member 47, and the storage chamber 48 is formed in the closing member 47.
A through hole 49 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 50 that can communicate with the hydraulic oil chamber 36 is bored, and a check valve 51 that only allows the hydraulic oil to flow from the storage chamber 48 to the hydraulic oil chamber 36 side is provided.

Next, the operation of this embodiment will be explained. When the intake valve 5 is fully closed, the hydraulic drive device 1O 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 lid 14, the volume of the hydraulic oil chamber 36 is reduced, and the hydraulic oil in the hydraulic oil chamber 36 passes through the one-way valve 46 to the damper chamber 35.
will be introduced in 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 35 is returned to the hydraulic oil chamber 36 through the communication hole 26. 40 is inserted into the communication hole 26, the throttling action by the throttling mechanism 41 is started, and the hydraulic fluid chamber 3 is drawn from the damper chamber 35.
6 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 when sitting is alleviated,
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 circulation restricted by the throttle mechanism 41 varies depending on the viscosity of the hydraulic oil, that is, the temperature of the hydraulic oil, when the circulation area of the micro passage 42 is constant, and when the temperature of the hydraulic oil is high, that is, the viscosity is low. Sometimes, the amount of hydraulic oil returning from the damper chamber 35 to the hydraulic oil chamber 36 is relatively large.
Further, when the temperature of the hydraulic oil is low, that is, when the viscosity is high, the amount of hydraulic oil returned from the damper chamber 35 to the hydraulic oil chamber 36 is relatively small. If the amount of hydraulic oil returned from the damper chamber 35 to the hydraulic oil chamber 36 differs in this way, the valve closing speed of the valve-side piston 13 will change. However, the communication hole 26 is connected to the heater 25.
Since the hydraulic oil can be heated by this heater 25, the temperature or viscosity of the hydraulic oil flowing through the micro passage 42 can be kept almost constant, and the hydraulic oil can be heated from the damper chamber 35 to the hydraulic oil chamber. It is possible to adjust the amount of hydraulic oil returned to 36 to be substantially constant, and therefore it is possible to avoid variations in the moving speeds of the valve-side piston 13 and the cam-side piston 15 in the valve-closing direction.

In the above embodiment, the communication hole 26 is formed by the heater 25, but a heater may be provided to keep the hydraulic oil in the hydraulic drive device IO at a substantially constant temperature at all times.
The present invention can also be applied to a device in which the valve opening/closing timing is adjusted by connecting a hydraulic pressure supply circuit and a hydraulic pressure release circuit to the hydraulic fluid chamber 36 and controlling the hydraulic pressure in the hydraulic fluid chamber 36. In order to keep the temperature of the hydraulic oil supplied into the hydraulic oil chamber 36 constant, a heater may be provided in the middle of the hydraulic pressure supply path. Furthermore, it goes without saying that the present invention can also be implemented in a valve operating system for an exhaust valve.

C1 Effects of the Invention As described above, the device of the present invention is equipped with a heater for heating the hydraulic oil in order to keep the viscosity of the hydraulic oil almost constant at all times, so the temperature of the hydraulic oil can be controlled almost constant and the viscosity can be changed. This makes it possible to prevent variations in the valve closing speed by preventing changes in the amount of hydraulic fluid squeezed by the throttle mechanism.

[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 of the main part of FIG. 2. 5... Intake valve, 9... Cam, 13... Valve side piston, 15... Cam side piston, 25... Heater, 3
5... Damper chamber, 36... Hydraulic oil chamber, 41... Throttle mechanism Figure 1 Figure 3 Chiku 2 M

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 between the hydraulic oil chamber, which the other end of the cam side piston faces, and the damper chamber, there is a hydraulic oil chamber that is operated from the damper chamber. A valve train for an internal combustion engine that is provided with a throttle mechanism that restricts the flow of hydraulic oil to an oil chamber, characterized by comprising a heater for heating the hydraulic oil in order to keep the viscosity of the hydraulic oil substantially constant at all times. Valve gear for internal combustion engines.