JPS6230282B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve drive device for driving intake and exhaust valves (hereinafter collectively referred to as on-off valves) provided in a combustion chamber of an internal combustion engine, and particularly to a valve drive device with a valve stop function. Regarding.

In order to improve the high-speed performance of internal combustion engines, four-valve engines, six-valve engines, eight-valve engines, etc., which are provided with a plurality of intake valves and a plurality of exhaust valves, are well known. In an internal combustion engine equipped with such multiple on-off valves, all the on-off valves are driven at high speeds to ensure a sufficient opening area for the intake and exhaust passages, while at medium to low speeds some of the on-off valves are deactivated and the remaining open/close valves are driven. It is known that a valve drive device is combined with a valve deactivation device in order to prevent the air-fuel mixture from blowing through due to so-called overlapping by driving only the on-off valve of the engine, thereby ensuring operational performance at medium and low speeds. There is. On the other hand, an example of a valve drive device having a valve stop function is disclosed in Japanese Patent Application Laid-Open No. 54-36415.

However, such conventional valve drive devices
The problem was that the structure was quite complex and lacked durability.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a valve drive device that has a simple structure and is highly durable.

In the valve drive device according to the present invention, a cam follower that engages with a cam that rotates with the rotation of the crankshaft and drives an on-off valve to open and close intermittently is pivotally supported by a hydraulic tappet mechanism, and the hydraulic tappet mechanism is rotated in the direction of its central axis. The hydraulic tappet mechanism is configured to be selectively positionable in either the raised position or the lowered position to position the hydraulic tappet mechanism in the lowered position to effect valve rest.

Hereinafter, a valve driving device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a part of a cylinder block of an internal combustion engine using a valve drive device according to the present invention. An on-off valve 4 consisting of a valve rod 5a connected to a valve body 5 forming an intake or exhaust valve, that is, an on-off valve 4, is slidably guided in a valve guide 6. The on-off valve 4 is biased by a known valve spring mechanism 7 in a direction to close the on-off valve 4. The tip of the valve rod 5a is in contact with one end of a cam follower 9 that is engaged with a cam 8. The other end of the cam follower 9 is pivotally supported by a spherical head of a piston plunger 11 forming an oil tappet mechanism 10, and is pressed by the rotation of a cam 8 that rotates in response to the rotation of a crankshaft (not shown). The valve rod 5a can be pressed by the valve rod 5a. The piston plunger 11 is slidably inserted from the open end into the control cylinder 12, which is formed into a cylindrical shape as a whole and has two protrusions 12a and 12b projecting outward in the radial direction on the periphery of the open end, and is inserted into the hydraulic chamber. 1
3 is formed. The piston plunger 11 and the control cylinder 12 together act as a pivot column member, and as the height increases, the hydraulic pressure increases in the hydraulic chamber 13 and assumes the oil tappet function.
The piston plunger 11 has a through passage 11a inside.
The through passage 11a has a piston plunger 11.
It communicates with the hydraulic chamber 13 through an orifice 11b at the bottom of the piston plunger 11, and opens at the tip of the spherical head of the piston plunger 11 to connect the cam follower 9.
Lubricating oil can be supplied between the spherical head and the spherical head. The through passage 11a further includes an orifice 1 provided on the side wall of the piston plunger 11.
It is connected to 1c. The control cylinder 12 has an orifice 12c in its side wall that communicates with the orifice 11c of the piston plunger 11. The control cylinder 12 is slidably inserted into the cam cylinder 14.

On the other hand, a compression spring 15 is provided within the hydraulic chamber 13 and urges the piston plunger 11 in a direction to push it out of the control cylinder 12. Also,
A spherical valve body 16 is provided in a retainer 17 at the bottom of the piston plunger 11 in the hydraulic chamber 13, and is pressed against the orifice 11b by a pressing spring 18 to form a check valve. As is clear from FIGS. 2B and 2C, the fixed cylindrical member or cam cylinder 14 has a pair of axially longitudinal grooves or notches 14a, which are engaged with the protrusion 12a12b of the control cylinder 12 at its upper peripheral edge.
14b. These notches 14a and 14b are
Three sides A, B forming valleys and ledges, respectively.
It consists of the face and the C face. A latch recess, that is, a radial locking groove, is formed at the deepest part on side D, which faces side B and forms a valley.
It has a shape that bites into the surface.

As is clear from FIG. 3, the tip 12aa of the protrusion 12a is shaped like a disk, and is held by a holding member 20 slidably supported on the shift rod 19. The clamping member 20 acts as an engaging member that engages with the pivot columnar member. In response to movement of the shift rod 19 in the direction of the central axis, for example in the direction of the arrow P, the control cylinder 12 rotates in the direction of the arrow Q. The positioning rod 19 is driven by a suitable drive device (not shown) so as to be located in either the valve actuation position or the valve rest position depending on the operating condition of the engine. In addition, the shift rods 1 on both sides of the clamping member 20
Spring fixing members 24 and 25 are fixedly attached to the clamping member 20, and a pair of bias springs 2 apply a balanced bias force to the clamping member 20 from both sides.
6 and 27 are provided.

On the other hand, a hydraulic pressure supply path 14c is formed in the side wall of the cam cylinder 14 and is in communication with the orifice 12c only when the control cylinder 12 is in the valve operating position, and communicates with an external hydraulic power source via the hydraulic path 21. . Further, the control cylinder 12 is biased by the return spring 22 in the direction of coming out of the cam cylinder 14, that is, in the direction of pushing up the cam follower 9.

The cam follower 9 is guided by a cam follower guide 23 so as to properly abut the tip of the valve rod 5a.

In the valve drive device according to the present invention configured as described above, when operating the on-off valve normally,
The relative position of control cylinder 12 with respect to cam cylinder 14 is positioned by shift rod 19 to the valve operating position shown in solid lines in FIG. 2C. That is, the protrusion 12a of the control cylinder 12,
12b are in contact with the C surface of the cam cylinder 14, the piston plunger 11 is in the raised position, and the swinging motion of the cam follower 9 is transmitted to the valve rod 5a.

Next, in this valve drive device, when the on-off valve is to be stopped despite the rotation of the cam 8, the shift rod 19 is moved, for example, in the P direction in FIG. 3, and the control cylinder 12 is rotated in the Q direction.
This rotation of the control cylinder 12 in the Q direction corresponds to the movement in the Q direction in FIG.
2b are notches 14a and 14b of the cam cylinder 14
(the position indicated by the dotted line in FIG. 2c). At this time, when the cam follower 9 is pressed by the cam 8, the control cylinder 12 is also pressed, and the protrusions 12a, 12b reach the deepest parts of the notches 14a, 14b, and the bias springs 26, 27 further push the surface D. A portion of the projections 12a, 12b engage within the latching recess. FIG. 4 shows such a state. In this state, the cam follower 9 is maintained in the state shown in FIG. 4 despite the rotation of the cam 8, and no pressing force is applied to the valve rod 5a, and the on-off valve 4 is in a rest state.

Next, when the shift rod 19 is moved in the direction opposite to the direction P in FIG. The protrusions 12a, 12b are further rotated in the direction opposite to the Q direction by the biasing force of the springs 26, 27 on the protrusion 12a, 12b.
reaches the position of the solid line in FIG. 2C. In such a state, the operation of the on-off valve according to the rotation of the cam 8 is restarted.

As described above, according to the present invention, when the on-off valve is not operating, the pivot cylindrical member is locked in the resting groove provided in the fixed cylindrical member, so when the valve is not operating, the cam follower repeatedly slides due to contact with the cam. Because there is no
No unnecessary vibration is added to the return spring, improving the durability of the mechanism.

In addition, when the valve is in the rest state, the force acting on the piston plunger 11 becomes almost zero, and if the hydraulic pressure continues to be supplied to the hydraulic chamber 13, the total height of the oil tappet becomes slightly higher, and when the valve rest state is released, the force acting on the piston plunger 11 becomes almost zero. There is a possibility that the control cylinder 12 is pushed in by the pressing force of the cam follower 9 before it is completely raised, resulting in a delay in returning to the valve operating state. However, in the valve driving device according to the present invention, when the control cylinder 12 is lowered to the valve rest position,
The structure is such that the hydraulic pressure supply to the hydraulic chamber 13 is cut off, so there is no problem as described above.

Furthermore, because of the springs 26, 27 which provide a balanced bias to the clamping member 20, the projection 12 of the control cylinder 12 can be moved by simply positioning the shift rod 19 in two positions: the valve actuation position and the valve rest position.
a, 12b are notches 14a of the cam cylinder 14,
14b, the control cylinder 12 is correctly positioned despite changes in the pressing force on the cam follower 9 caused by the rotation of the cam 8.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a part of a cylinder block of an internal combustion engine including a valve driving device according to the present invention, and FIGS. 2A and 2B show main parts of the valve driving device shown in FIG. 1. FIG. 2C is a developed view of the members shown in FIG. 2B, FIG. 3 is a partial plan view of the valve drive device shown in FIG. 1, and FIG.
FIG. 3 is a sectional view showing the valve driving device shown in the figure in a valve rest state. Explanation of symbols of main parts: 1...Cylinder head, 2...Intake or exhaust passage, 3...Combustion chamber, 4...Opening/closing valve, 5...Valve body, 5a...Valve rod, 7...Valve spring mechanism , 8...Cam, 9...Cam follower, 10...Oil tappet mechanism, 11...Piston plunger, 12...
Control cylinder, 14...Cam cylinder, 19...
Shift rod, 20... Holding member, 26, 27...
...bias spring.

Claims (1)

[Scope of Claims] 1. A cam that rotates in accordance with the rotation of the crankshaft of an internal combustion engine, a cam follower that responds to the cam and drives an on-off valve of the internal combustion engine at one end thereof, and pivots the other end of the cam follower. and a pivot columnar member having at least one protrusion projecting in the radial direction from its peripheral edge, and an axial longitudinal groove into which the pivot columnar member is slidably inserted and into which the protrusion can fit. a fixed cylindrical member having a fixed cylindrical member; an elastic member that urges the pivot cylindrical member and the fixed cylindrical member in a direction away from each other; positioning means for determining the relative angular position of the pivot column member, and when the pivot column member is positioned at a predetermined angular position with respect to the fixed cylindrical member by the positioning means, the protrusion of the pivot column member The pivot cylindrical member is fitted into the axial longitudinal groove of the fixed cylindrical member so as to be pushed into the fixed cylindrical member and absorb the pressing force applied to the cam follower to perform a valve stopping action. , the fixed cylindrical member is provided so as to be continuous with the deepest part of the axial longitudinal groove, and is engaged with the protruding part when the protruding part of the pivoting columnar member is fitted into the deepest part of the axial longitudinal groove. A valve drive mechanism characterized by having mating radial locking grooves. 2. The positioning means is one of the pivot columnar members.
a shift rod slidably carrying the engaging member and movable in a tangential direction to the pivoting columnar member; 2. The valve drive mechanism according to claim 1, further comprising a pair of bias springs provided on a shift rod to sandwich said engagement member.