JPH079168B2 - Valve drive for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention relates to a cam provided on a camshaft driven by a crankshaft and an intake valve spring-biased in a valve closing direction. Alternatively, the valve-side piston intakes to open the intake valve or the exhaust valve in response to an increase in the hydraulic pressure of the hydraulic oil chamber facing the other end of the cam-side piston that is linked to the cam and connected to the exhaust valve. The present invention relates to a valve operating system of an internal combustion engine in which a hydraulic drive mechanism that is interlocked with and connected to a valve or an exhaust valve is interposed, and a hydraulic pressure release valve is connected to the hydraulic oil chamber to release hydraulic pressure when the valve is opened.

(2) Conventional Technology Conventionally, such a valve operating device is known, for example, from Japanese Patent Application Laid-Open No. 61-229912.

(3) Problems to be Solved by the Invention By the way, in such a valve operating device, it is necessary to promptly activate the hydraulic release valve when the engine is rotating at a high speed. It is difficult to make the response speed of this solenoid valve correspond to the high engine speed.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a valve operating system for an internal combustion engine, in which the operation of the hydraulic pressure release valve is made to correspond to the rotation of the engine, and it is possible to sufficiently cope with it even at a high rotation speed. To aim.

B. Configuration of the Invention (1) Means for Solving the Problems According to the present invention, the hydraulic pressure release valve is provided with a housing having an outlet oil passage communicating with the hydraulic oil chamber and a circumferential opening for constantly communicating with the outlet oil passage. An outer shaft that is formed in a cylindrical shape having a first valve hole that is elongated in the direction and is bored in the side wall, and that is fitted into the housing so as to be rotatable about an axis.
It is rotatably fitted in a cylindrical outer shaft having a second valve hole extending in a radial direction on a side wall at a position corresponding to the first valve hole so as to communicate with an oil pressure release passage formed inside. And an inner shaft that is linked and connected to the cam shaft.

(2) Operation According to the above configuration, by rotating the outer shaft, it is possible to shift the timing at which the first and second valve holes communicate with each other, thereby adjusting the valve opening timing of the hydraulic pressure release valve. can do. Moreover, since the inner shaft is interlocked with and connected to the cam shaft, the operation of the hydraulic pressure release valve can be made to correspond to the rotation speed of the engine, and it is also possible to cope with the high rotation of the engine.

(3) Embodiment Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, in FIGS. 1 and 2, a pair of intake air urged in a valve closing direction by a valve spring 1 is applied to an engine body (not shown). The valves 2 are arranged to open and close, and the cam shaft 3 rotatably arranged above the intake valves 2 is provided with the cams 4 at positions corresponding to the intake valves 2. A crank shaft (not shown) is interlocked and connected to the cam shaft 3, and the cam shaft 3 is rotationally driven at a speed reduction ratio of 1/2 according to the rotation of the engine.

A hydraulic drive mechanism 5 for driving the intake valve 2 to open and close according to the profile of the cam 4 is interposed between the cam 4 and the intake valve 2, and the hydraulic drive mechanism 5 for pressing the intake valve 2 downward. A hydraulic release valve 6 for shutting off the pressing force during the valve opening operation is connected to the hydraulic drive mechanism 5.

The hydraulic drive mechanism 5 is provided on a support portion 7 fixed to the engine body, and extends vertically above the intake valve 2 and is fitted and fixed to the support portion 7. The valve-side piston 9 that abuts on the upper end of 2 and is slidably fitted on the lower part of the cylinder body 8, the lifter 10 that slides on the cam 4 of the cam shaft 3, and the upper end abuts on the lifter 10. Cam-side piston 11 slidably fitted on the top of the cylinder body 8
With.

A partition wall 12 for partitioning the inside of the cylinder body 8 into upper and lower parts is provided in the middle portion of the cylinder body 8, and the valve side piston 9 is
A damper chamber 13 is defined between the partition wall 12 and the cylinder body 8
Is slidably fitted to the lower part of the cylinder side, and the cam side piston 11 is slidably fitted to the upper part of the cylinder body 8 by defining a hydraulic oil chamber 14 between the cam side piston 11 and the partition wall 12. A communication hole 15 is formed in the center of the partition wall 12 to allow communication between the damper chamber 13 and the hydraulic oil chamber 14.
Is formed.

An oil chamber 16 is formed in the valve side piston 9. Moreover, a short cylindrical portion 17 that can communicate with the communication hole 15 is coaxially projected at the center of the upper end of the valve-side piston 9 so that it can communicate with the oil chamber 16. Aperture 15 and aperture 18
Is configured. That is, the outer diameter of the short cylindrical portion 17 is equal to the communication hole 15
It is set so that a space of several tens to several hundreds of μm is formed between the short cylinder portion 17 and the communication hole 15 in a state where the short cylinder portion 17 is inserted into the communication hole 15.
A minute annular passage is formed between them, and this annular passage restricts the flow of the hydraulic oil from the damper chamber 13 to the hydraulic oil chamber 14. Moreover, the annular passage, that is, the throttle 18 is formed
It is only when the short cylindrical portion 17 is inserted into the communication hole 15, and the axial length of the short cylindrical portion 17 is upward during the closing operation of the intake valve 2, that is, the valve side piston 9 is pushed upward by the valve spring 1. It is set so as to be inserted into the communication hole 15 during the course.

The oil chamber 16 of the valve side piston 9 is opened when the hydraulic pressure in the short cylindrical portion 17 is higher than the oil chamber 16 by a certain value to guide the working oil from the short cylindrical portion 17 into the oil chamber 16. The directional valve 19 is housed, and the valve side piston 9 is provided with a through hole 20 for communicating the oil chamber 16 with the damper chamber 13. Therefore, when the hydraulic pressure in the hydraulic oil chamber 14 is increased while the short cylindrical portion 17 is inserted in the communication hole 15, the hydraulic oil in the hydraulic oil chamber 14 is guided from the oil chamber 16 to the damper chamber 13.

Therefore, the throttle 18 is moved upward by the valve spring 1 when the short cylindrical portion 17 is below the communication hole 15, that is, when the intake valve 2 is pushed down to perform the valve opening operation. When the valve is pushed up to the halfway and the valve is partially closed, the throttle action is not performed, and the short cylindrical portion 17 is inserted into the communication hole 15 during the valve closing operation until the intake valve 2 is fully closed. The squeezing action will be performed only for a while.

The cam-side piston 11 is formed in a bottomed cylindrical shape with the closed end facing downward, and the upper open end of the cam-side piston 11 is closed by a closing member 21 capable of contacting the lifter 10. The lifter 10 is formed into a cylindrical shape with a bottom so that the outer surface of the lifter 10 is brought into sliding contact with the cam 4, and is slidably fitted on the upper portion of the support portion 7.

A storage chamber 22 is formed between the cam side piston 11 and the closing member 21, and the closing member 21 has a through hole for guiding the working oil stored in the storage chamber 22 to a sliding contact portion with the lifter 10. 23 is drilled. Further, an oil hole 24 that can communicate with the hydraulic oil chamber 14 is formed at the closed end of the cam side piston 11, and a check valve that allows only the hydraulic oil to flow from the storage chamber 22 to the hydraulic oil chamber 14 side. Valve 25
Is provided.

An inlet hole 26 communicating with the hydraulic oil chamber 14 is bored in the cylinder body 8, and an inlet oil passage 27 communicating with the inlet hole 26 is bored in the support portion 7. Moreover, this inlet oil passage 27 is a hydraulic oil chamber.
It is connected to a hydraulic pressure supply source 29 via a check valve 25 that blocks the flow of hydraulic oil from the 14th side. The hydraulic supply source 29 includes a hydraulic pump 31 that pumps hydraulic oil from an oil tank 30, and a reserve chamber 32 that stores hydraulic oil discharged from the hydraulic pump 31, and the inlet oil passage 27 is Check valve 28
Is connected to the reserve chamber 32 via.

An outlet hole 33 communicating with the hydraulic oil chamber 14 is bored in the cylinder body 8, and the outlet hole 33 includes a first outlet oil passage 34, a hydraulic pressure release valve 6, and a second outlet provided in the support portion 7. It is connected to the reserve chamber 32 of the hydraulic pressure supply source 29 via an oil passage 35 and a check valve 36. Moreover, the check valve 36 has a function of blocking the flow of hydraulic oil from the reserve chamber 32 side.

In such a hydraulic drive mechanism 5, the intake valve 2 is in the fully closed state as shown in the first illustration, and the lifter 10 is pushed down by the rotation of the camshaft 3 from this first illustration. The cam side piston 11 is pressed downward by this lifter 10,
When the volume of the hydraulic oil chamber 14 is reduced and the hydraulic pressure release valve 6 is closed, the hydraulic oil in the hydraulic oil chamber 14 is a one-way valve.
It is introduced into the damper chamber 13 via 19. As a result, the valve side piston 9 is pressed downward, and the intake valve 2 is driven to open against the spring force of the valve spring 1.

After the intake valve 2 is fully open, the cam 4 lifts the lifter.
When the pressing force on 10 is released, the intake valve 2 is driven upward by the spring force of the valve spring 1, that is, in the valve closing direction. The valve-side piston 9 is also pushed upward by the closing operation of the intake valve 2, and the hydraulic oil in the damper chamber 13 passes through the communication hole 15 and the hydraulic oil chamber 14
However, the short cylindrical part 17 has a communication hole during the valve closing operation.
After being inserted in 15, the throttle action by the throttle 18 is started, and the flow of the hydraulic oil from the damper chamber 13 to the hydraulic oil chamber 14 is restricted. Therefore, the moving speed of the intake valve 2 in the upward direction, that is, the valve closing speed is relaxed during the valve closing operation.
Will slowly close. Therefore, the impact at the time of seating is mitigated, and damage to the intake valve 2, the valve seat member (not shown), etc. can be prevented as much as possible.

The hydraulic pressure release valve 6 includes a support portion 7 as a housing and a first support portion 7.
It is formed in a cylindrical shape having a first valve hole 37 which is long in the circumferential direction and is bored in the side wall so as to be constantly in communication with the outlet oil passage 34, and enables the support portion 7 to rotate about the axis. An outer shaft 38 to be fitted and a cylindrical portion 41a having a second valve hole 40 extending in the radial direction so as to communicate with a hydraulic pressure release passage 39 formed inside are provided on a side wall at a position corresponding to the first valve hole 37. And an inner shaft 41 that is rotatably fitted in the outer shaft 38.

The support portion 7 is provided with a support hole 42 extending in a direction orthogonal to the axis of the cylinder body 8 of the hydraulic drive mechanism 5, and a pair of support holes 42 are formed on the inner surface of the support hole 42 at positions axially spaced from each other. A recess 43 is provided. These recesses 43 are support holes
A pair of first outlet oil passages 34, which are formed in an arc shape long in the circumferential direction of 42 and communicate with the hydraulic oil chambers 14 of the pair of hydraulic drive mechanisms 5, respectively communicate with the respective recesses 43. An outer shaft 38 is fitted in the support hole 42 so as to be rotatable about its axis, and the inner surface of the support hole 42 and the outer shaft 42 are sealed to seal both sides of the recess 43 along the axial direction.
Three seal members 44, 45, 46 are interposed between the 38. In addition, an annular groove communicating with the second outlet oil passage 35 is formed on the inner surface of the support hole 42.
47 is formed at a position axially displaced from the recess 43.

First valve holes 37 are formed in the outer shaft 38 at positions corresponding to the recesses 43, respectively.
37 is formed to be long in the circumferential direction of the outer shaft 38 so as to always communicate with the recess 43 even when the outer shaft 38 rotates about its axis. The outer shaft 38 also has a gear 48 on the outer surface.
A rack 49 meshing with the gear 48 is movably supported in a direction perpendicular to the axis of the outer shaft 38 and supported by the support portion 7, and the rack 49 is connected to a driving means (not shown). . Therefore, by driving the rack 49 in its longitudinal direction, the outer shaft 38 is angularly displaced about the axis. Further, the outer shaft 38 is provided with an oil hole 50 which is in constant communication with the annular groove 47.

A cylindrical portion 41a is formed on one end side of the inner shaft 41, and the cylindrical portion 41a is rotatably fitted in the outer shaft 38. Moreover, the inner shaft 4 is provided in the cylindrical portion 41a.
The hydraulic pressure release passage 39 is formed by being closed by the cap 51 fitted to the end portion of the first valve hole 40, and the second valve hole 40 communicating with the hydraulic pressure release passage 39 is formed.
Are radially extended at positions corresponding to the first valve holes 37. Moreover, an annular groove 52 communicating with the oil hole 50 is provided on the outer surface of the cylindrical portion 41a, and an oil passage 53 is connected between the annular groove 52 and the hydraulic pressure release passage 39. Therefore, the hydraulic pressure release passage 39 always communicates with the second outlet oil passage 35.
Further, three seal members 54, 55, 56 are interposed between the inner shaft 41 and the outer shaft 38 to seal the connecting portions of the first and second valve holes 37, 40.

The inner shaft 41 is coaxially connected to a driven shaft 57 rotatably supported by the support portion 7 via a joint (not shown), and a driven gear 58 provided with a serrated mechanism on the driven shaft 57. The drive gear 59 fixed to the camshaft 3 is meshed.

Therefore, the inner shaft 41 is interlocked with the cam shaft 3,
Will be connected.

In the hydraulic pressure release valve 6, the inner shaft 41 rotates in response to the rotation of the cam shaft 3 so that the first and second valve holes 37 and 40 communicate with each other to open the valve. , The outer shaft 38 is angularly displaced by the rack 49.

Next, the operation of this embodiment will be described. In the hydraulic drive mechanism 5, the cam side piston 11 is pressed downward by the cam 4 to open the hydraulic release valve 6 while the intake valve 2 is being opened. When the valve is actuated, the hydraulic pressures of the hydraulic oil chamber 14 and the damper chamber 13 are released to the reserve chamber 32, so that the downward force applied to the valve side piston 9 is canceled, and the valve side piston 9 and the intake valve 2 have the valve spring 1 The valve is driven upward by the spring force of and the valve closing operation starts. That is, the intake valve 2 starts to close before the intake valve 2 reaches the fully open state. Therefore, by selecting the opening timing of the hydraulic pressure release valve 6, it becomes possible to freely and easily set the closing timing of the intake valve 2 as shown in FIG.

Moreover, the opening timing of the hydraulic pressure release valve 6 can be arbitrarily set by angularly displacing the outer shaft 38 by the rack 49, and therefore, the closing timing of the intake valve 2, that is, the lift amount can also be arbitrarily set. Further, since the inner shaft 41 of the hydraulic pressure release valve 6 is interlocked with and connected to the camshaft 3,
The operating speed of the hydraulic pressure release valve 6 corresponds to the operating state of the engine, and therefore can sufficiently correspond to the high engine speed.

Although the valve operating device for the intake valve 2 has been described in the above embodiment, it goes without saying that the present invention can be implemented for the valve operating device for the exhaust valve.

C. Effects of the Invention As described above, according to the present invention, the hydraulic pressure release valve is provided with a housing having an outlet oil passage communicating with the hydraulic oil chamber and a circumferentially long side wall so as to always communicate with the outlet oil passage. An outer shaft that is formed in a cylindrical shape with a first valve hole that is bored and that is fitted into the housing so that it can rotate about an axis, and a radius that leads to a hydraulic pressure release path that is formed inside. Is formed in a cylindrical shape having a second valve hole extending in the direction on the side wall at a position corresponding to the first valve hole, is rotatably fitted in the outer shaft, and is interlocked with the cam shaft,
With the inner shaft connected, the operating speed of the hydraulic release valve can be made to correspond to the operating state of the engine.
Even if the engine has a high rotation speed, it can respond sufficiently.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a vertical cross-sectional side view showing the overall structure and is a cross-sectional view taken along the line II of FIG. 2, and FIG. 2 is II- of FIG. II line enlarged sectional view, FIG. 3 is a characteristic diagram. 2 ... intake valve, 3 ... cam shaft, 4 ... cam, 5 ...
... Hydraulic drive mechanism, 6 ... Hydraulic release valve, 7 ... Housing support, 9 ... Valve side piston, 11 ... Cam side piston, 34,35 ... Outlet oil passage, 37 ... First valve Hole, 38 ……
Outer shaft, 39 ... hydraulic release path, 40 ... second valve hole,
41 …… Inner shaft

Claims (1)

[Claims] 1. A cam side in which one end is interlocked with and connected to a cam provided on a cam shaft driven by a crankshaft and an intake valve or an exhaust valve which is spring-biased in a valve closing direction. A hydraulic drive mechanism, in which a valve side piston is linked and linked to an intake valve or an exhaust valve to open the intake valve or the exhaust valve in response to an increase in the hydraulic pressure of the hydraulic oil chamber facing the other end of the piston, is interposed. In a valve operating system of an internal combustion engine, wherein a hydraulic pressure release valve is connected to the hydraulic oil chamber to release the hydraulic pressure when the valve is opened, the hydraulic pressure release valve includes a housing having an outlet oil passage communicating with the hydraulic oil chamber, and an outlet. An outer that is formed in a cylindrical shape and has a first valve hole that is long in the circumferential direction and is bored in the side wall so as to be in continuous communication with the oil passage, and that is fitted into the housing so as to be rotatable about its axis. Shaft and hydraulic pressure formed inside A second valve hole extending in the radial direction to communicate with the discharge passage is formed in a cylindrical shape on a side wall at a position corresponding to the first valve hole, rotatably fitted in the outer shaft, and interlocked with the cam shaft, A valve train for an internal combustion engine, comprising: an inner shaft connected to the inner shaft.