JPH0612059B2 - 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 valve operating device for an internal combustion engine for driving a pair of engine valves to open and close, and particularly to a pair of engines in a low speed operating range and a high speed operating range of the engine. The present invention relates to a valve operating device for an internal combustion engine, which is configured to change a valve opening / closing operation mode.

(2) Prior Art Conventionally, a valve operating system in which the opening / closing operation mode of a pair of intake valves or exhaust valves is changed between a low speed operation range and a high speed operation range of an engine is disclosed in, for example, Japanese Patent Laid-Open No. 61-991. It is disclosed in.

(3) Problem to be Solved by the Invention In the above-mentioned conventional one, between the first and second drive rocker arms that are individually interlocked with and connected to a pair of intake valves, a high-speed engine having a shape corresponding to a high-speed operating range of the engine is used. A free rocker arm that slidably contacts the cam and can be free with respect to both intake valves is arranged, and in the low speed operation range of the engine, the connection of each rocker arm is released to make the opening and closing operation mode of both intake valves correspond to the low speed operation range. In the high-speed operating range of the engine, the rocker arms are connected to each other so that the high-speed cam allows the opening and closing operation modes of both intake valves to correspond to the high-speed operating range.

Thus, the hydraulic connection switching means for switching connection and disconnection between the rocker arms is a connection position for fitting to the free rocker arm while forming a hydraulic chamber with the first drive rocker arm, and its fitting. A connection piston that is movable between connection release positions to release the state, and is slidably fitted to the first drive rocker arm, and a second piston that is slidably fitted to the free rocker arm while being in contact with the connection piston. It is equipped with a connecting piston that can move between a connecting position that fits into the rocker arm and a disconnecting position that releases the fitted state, and can switch between connecting and disconnecting each rocker arm according to the hydraulic control of the hydraulic chamber. Is configured.

By the way, since the free rocker arm is in sliding contact with the high-speed cam, it is necessary to keep the surface pressure of the sliding contact surface with the high-speed cam relatively small when the rocker arms are connected in the high-speed operation range of the engine. The width of the free rocker arm along the rotation axis is set to be relatively large. On the other hand, from the viewpoint of the surface pressure, the widths of the first and second drive rocker arms along the rotation axis may be set to be relatively small.
However, in the above-mentioned conventional hydraulic connection switching means, the first drive rocker arm is provided with the hydraulic chamber, and the width along the rotation axis of the first drive rocker arm must be set large in order to form the hydraulic chamber. Not only that, the space occupied by each rocker arm increases correspondingly, and the valve operating load also increases.

The present invention has been made in view of the above circumstances, and effectively reduces the space occupied by each rocker arm by effectively forming the hydraulic chamber of the hydraulic connection switching means in the free rocker arm having a relatively large width along the rotation axis. Another object of the present invention is to provide a valve operating device for an internal combustion engine, which reduces the valve operating load.

B. Configuration of the Invention (1) Means for Solving the Problems According to the present invention, the camshaft that is rotationally driven in synchronization with the rotation of the engine includes a first cam having a shape corresponding to a high-speed operating range of the engine. A pair of engine valves provided on both sides of a free rocker arm slidably contacting the first cam, the second and third cams having a shape corresponding to a low speed operation range of the engine and arranged on both sides of the first cam. First and second members that are individually interlocked with and connected to each other and individually slidably contact the second and third cams.
Drive rocker arms are arranged adjacent to each other, and hydraulic connection switching means are provided between the free rocker arm and the first drive rocker arm, and between the free rocker arm and the second drive rocker arm, and both hydraulic connection switching means are connected to the free rocker arm. The hydraulic chamber is defined by the piston and the spring-biased piston is coupled to the drive rocker arm adjacent to the free rocker arm, and the engagement is released from the drive rocker arm adjacent to the free rocker arm. The movable rocker arm is slidably fitted to the free rocker arm so that it can move in response to a change in the hydraulic pressure of the hydraulic chamber between it and the disconnection position.

(2) Operation According to the above configuration, the hydraulic connection switching means provided between the free rocker arm and the first drive rocker arm, and the hydraulic chamber of the hydraulic connection switching means provided between the free rocker arm and the second drive rocker arm are By effectively forming each of the free rocker arms whose width along the axis of motion is set to be relatively large, both drive rocker arms do not need to be hydraulically operated, so that the width along the axis of rotation can be reduced. It will be possible.

(3) Embodiment Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, referring to FIGS. 1 and 2, each cylinder of a multi-cylinder internal combustion engine has intake valves 1a as a pair of engine valves, 1b is provided, and the intake valves 1a and 1b are opened and closed by a first cam 5 which is integrally provided on a camshaft 2 which is driven at a rotation ratio of 1/2 in synchronization with the rotation of the engine. Driven.

Moreover, in the specific cylinder, the second and third circular cams 3a and 3b adjacent to the first cam 5 are integrated with the camshaft 2, and when the engine is operating at a low speed, both cams 3a and 3b work. The operation of both intake valves 1a and 1b is stopped.

Hereinafter, only the configuration of the valve operating device in the specific cylinder will be described.

The cam shaft 2 is rotatably arranged above the engine body, and the first cam 5 is integrally provided on the cam shaft 2 at a position corresponding to the middle of the intake valves 1a and 1b. The second and third cams 3a and 3b are arranged on both sides of the first cam 5. Moreover, the first cam 5 has the high-order portion 5a protruding in the radial direction from the base circular portion 5b, and the second and third cams 3a and 3b are formed in a perfect circular shape corresponding to the base circular portion 5b. .

The rocker shaft 6 is fixedly arranged below the cam shaft 2. The rocker shaft 6 includes a free rocker arm 7 corresponding to the first cam 5 and second and third cams 3.
First and second drive rocker arms 8 corresponding to a and 3b
a, 8b are pivotally supported, and each rocker arm 7, 8a, 8b
Slippers 10, 11a, 11b that are in sliding contact with the first cam 5, the second cam 3a, and the third cam 3b are respectively provided on the upper part of the. Also, the first and second drive rocker arms 8
Reference characters a and 8b extend above the intake valves 1a and 1b, and tappet screws 12 and 13 that can come into contact with the upper ends of the intake valves 1a and 1b are screwed at their tips so as to advance and retract.

On the other hand, flanges 14 and 15 are provided above the intake valves 1a and 1b, and a valve spring 16 surrounding the intake valves 1a and 1b is provided between the flanges 14 and 15 and the engine body. , 1
7 is interposed and the valve springs 16 and 17 urge the intake valves 1a and 1b upward, that is, toward the valve closing direction.

In FIG. 3, on the lower surface of the end of the free rocker arm 7,
A lifter 19 having a bottomed cylindrical portion is in contact with the lifter 19 and is urged upward by a lifter spring 20 interposed between the lifter 19 and the engine body. As a result, the slipper 10 of the free rocker arm 7 is always elastically brought into sliding contact with the first cam 5. Moreover, the spring force of the lifter spring 20 is set to be relatively weak.

In FIG. 4, the rocker arms 7, 8a, 8b are in sliding contact with each other, and a hydraulic connection switching means 21a is provided between the free rocker arm 7 and the first drive rocker arm 8a, and the free rocker arm 7 and the second drive Between the rocker arms 8b, a hydraulic connection switching means 21b having basically the same structure as the hydraulic connection switching means 21a is provided.

The hydraulic connection switching means 21a includes a piston 23 movable between a position for connecting the free rocker arm 7 and the first drive rocker arm 8a and a position for releasing the connection, a stopper 24 for restricting the movement of the piston 23, and a stopper. And a spring 25 for urging 24 toward the piston 23 side.

The free rocker arm 7 has a first guide hole 26 that is open toward the first drive rocker arm 8a side and is parallel to the rocker shaft 6, and a step is formed on the closed end side of the first guide hole 26. A small diameter portion 28 is provided via the portion 27. A piston 23 is slidably fitted in the first guide hole 26, and a hydraulic chamber 29 is defined between the piston 23 and the closed end of the first guide hole 26.

The free rocker arm 7 has an oil passage 3 communicating with the hydraulic chamber 29.
0 is bored, and an oil passage 31 communicating with a hydraulic pressure supply source (not shown) is bored in the rocker shaft 6. Further, the two oil passages 30 and 31 are always communicated with each other via the communication hole 32 formed in the side wall of the rocker shaft 6 regardless of the rocking state of the free rocker arm 7.

The first drive rocker arm 8a is provided with a second guide hole 35 corresponding to the first guide hole 26 and opened toward the free rocker arm 7 side. The second guide hole 35 has a disc-like shape. The stopper 24 is slid. Second guide hole 35
A small diameter portion 37 is provided on the closed end side through a regulation step portion 36, and the insertion hole 3 coaxial with the small diameter portion 37 is provided at the closed end.
8 is drilled. Moreover, the guide rod 39 provided coaxially and integrally with the stopper 24 is inserted into the insertion hole 38. Further, a coiled spring 25 surrounding the guide rod 39 is interposed between the stopper 24 and the closed end of the second guide hole 35.

The axial length of the piston 23 is such that, when one end of the piston 23 comes into contact with the step portion 27, the other end is positioned between the free rocker arm 7 and the first drive rocker arm 8a, and the stopper 24 is provided on the regulating step portion 36. It is set so that one end remains in the first guide hole 26 when it is inserted into the second guide hole 35 until it abuts.

The hydraulic connection switching means 21b has the same structure as the hydraulic connection switching means 21b, so a detailed description of its structure will be omitted. However, the hydraulic connection switching means 21b is omitted.
The hydraulic chamber 29 of b is formed in the free rocker arm 7 with a partition wall separated from the hydraulic chamber 29 of the hydraulic connection switching means 21a, and the hydraulic chambers 29, 2 of both the connection switching means 21a, 21b are formed.
9 is commonly connected to the oil passage 31. Therefore, both connection switching means 21a, 21b simultaneously perform switching operation between connection and disconnection.

Next, the operation of this embodiment will be described. When the engine is operated at a low speed, as shown in FIG. 4, the two hydraulic connection switching means 21a, 21b are used between the free rocker arm 7 and the first drive rocker arm 8a and the free rocker arm 7b. And the connection state between the second drive rocker arm 8b is released. That is, both hydraulic connection switching means 21a, 21b
When the hydraulic pressure in the hydraulic chamber 29 is released, the stopper 24 moves to the free rocker arm 7 side by the spring force of the spring 25, and the piston 23 is retracted until it abuts the step 27. In this state, the contact surfaces of the piston 23 and the stopper 24 are the sliding contact surfaces of the free rocker arm 7 and the first drive rocker arm 8a, and the free rocker arm 7 and the second rocker arm 7.
At the position corresponding to the sliding contact surface of the drive rocker arm 8b,
Thus the free rocker arm 7 and the first and second
The drive rocker arms 8a and 8b are in sliding contact with each other and are in a state capable of relative angular displacement.

In such a disengaged state, the first and second drive rocker arms 8a and 8b slidably contacting the second and third cams 3a and 3b, and the second and third cams 3a and 3b are circular. Therefore, both intake valves 1a and 1b remain closed without swinging. At this time, the free rocker arm 7 swings in response to the rotation of the first cam 5, but this swinging motion does not affect the operation of both intake valves 1a, 1b. Moreover, since the free rocker arm 7 is only in sliding contact with the first cam 5 by the relatively weak spring force of the lifter spring 20, the wear loss of the valve train can be kept low.

In this way, during low-speed operation of the engine, the intake valves 1a and 2b of the specific cylinders remain in the closed state by suspending their operation, so that fuel consumption can be reduced.

For high speed operation of the engine, the double hydraulic connection switching means 21
As shown in FIG. 5, the free rocker arm 7 and the first drive rocker arm 8a, and the free rocker arm 7 and the second drive rocker arm 8b are connected by a and 21b, respectively. That is, when the hydraulic pressure is supplied to both hydraulic chambers 29, 29, the piston 23 presses the stopper 24 against the spring force of the spring 25 and the second guide hole 3
5, the stopper 24 is pressed against the regulation step portion 36. In this state, the free rocker arm 7 and the first and second drive rocker arms 8a and 8b are prevented from rotating relative to each other and swing integrally.

In this connected state, the first and second drive rocker arms 8a and 8b swing following the swinging motion of the free rocker arm 7 that slidably contacts the first cam 5, and both intake valves 1a and 1b move to the first
The cam 5 opens and closes at the timing determined by the cam 5 and the lift amount.

In such a valve operating device, the free rocker arm 7 is in sliding contact with the first cam 5 having a shape corresponding to the high-speed operating range of the engine, and the free rocker arm 7 rotates in order to prevent the surface pressure of the slipper 10 from increasing. The width along the axis of motion is set relatively large. Thus, both hydraulic connection switching means 21a, 2
The hydraulic chambers 29, 29 of 1b are used for the free rocker arm 7, and effectively form a pair of hydraulic chambers 29, 29 in the free rocker arm 7 having a relatively large width along the rotation axis. The width along the rotation axis of the two-drive rocker arms 8a and 8b can be set to be relatively small. Therefore, the space occupied by each rocker arm 7, 8a, 8b can be made relatively small to achieve compactness, and the weight of each rocker arm 7, 8a, 8b can be reduced to reduce the valve operating load.

In the above embodiments, the valve operating system for the pair of intake valves 1a and 1b has been described, but the present invention can also be implemented in connection with the pair of exhaust valves.

C. As described above, according to the present invention, the hydraulic connection switching means provided between the free rocker arm and the first drive rocker arm, and the hydraulic chamber of the hydraulic connection switching means provided between the free rocker arm and the second drive rocker arm. Are effectively formed on the free rocker arms whose widths along the rotation axis are set to be relatively large, thereby making it possible to reduce the widths along the rotation axis of both drive rocker arms, thereby reducing the valve operating device. It is possible to make it compact and reduce the valve operating load.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a vertical side view and is a sectional view taken along the line I--I of FIG. 2, FIG. 2 is a plan view of FIG. 1, and FIG. III-III sectional view of FIG. 2, 4th
The figure is a sectional view taken along the line IV-IV of FIG.
FIG. 5 is a sectional view corresponding to FIG. 4 in the connected state. 1a, 1b ... intake valve as an engine valve, 2 ... cam shaft, 3a ... second cam, 3b ... third cam, 5 ... first cam, 7 ... free rocker arm, 8a ... first Drive rocker arm, 8b ... Second drive rocker arm, 21a,
22b ... hydraulic connection switching means, 23 ... piston, 2
9 ... Hydraulic chamber

Claims (1)

[Claims] 1. A valve operating system of an internal combustion engine for opening and closing a pair of engine valves (1a, 1b), wherein a camshaft (2) which is rotationally driven in synchronization with the rotation of the engine has a high engine speed. A first cam (5) having a shape corresponding to the driving range,
The second and third cams (3a, 3a, 3a, 3a, 3c, 3c, 3c, 3c, 3c, 3c, 3c having a shape corresponding to the low speed operation range of the engine and arranged on both sides of the first cam (5)
3b) are provided, and the pair of engine valves (1a, 1a, 1a, 3b) are provided on both sides of the free rocker arm (7) which is in sliding contact with the first cam (5).
1b) which are individually interlocked with and connected to the first and second cams (3a, 3b) and individually slidably contact with each other.
The drive rocker arms (8a, 8b) are arranged adjacent to each other, and the free rocker arm (7) and the first drive rocker arm (8
a) and between the free rocker arm (7) and the second drive rocker arm (8b).
1a, 21b) are provided respectively, and both hydraulic connection switching means (21a, 21b) define a hydraulic chamber (29) between the free rocker arm (7) and the hydraulic chamber (2).
The piston (23) spring-biased to the 9) side is adjacent to the free rocker arm (7) and the drive rocker arm (8a, 8a).
Depending on the change in the hydraulic pressure of the hydraulic chamber (29) between the connection position where it is fitted to b) and the connection release position where the fitting to the drive rocker arm (8a, 8b) adjacent to the free rocker arm (7) is released. A valve operating device for an internal combustion engine, which is slidably fitted to a free rocker arm (7) so as to be movable.