JPS64566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a rocker to be rocked by a cam having a lower portion formed by a circumferential surface on a reference circle and a higher portion bulging outward in the radial direction from the lower portion. a cam follower pivotally supported by the arm shaft;
A valve lifter that is pivotally supported on the rocker arm shaft independently of the cam follower and is interlocked and connected to the intake valve or exhaust valve, and an operating position that connects the cam follower and the valve lifter, and a non-operating position that releases the connection state. The present invention relates to a valve train for an internal combustion engine that includes an operation switching device that can switch the position of a connecting member that is movable between positions depending on the rotational speed of the engine.

Hitherto, high-speed internal combustion engines have been known in which one cylinder of the engine has at least one of a plurality of intake valves and exhaust valves. When a plurality of intake valves and exhaust valves having the same function are partially deactivated during load, and all intake valves and exhaust valves are operated during high load,
High efficiency can be obtained in the entire operating range of the engine.

In addition, in a multi-cylinder internal combustion engine, if the intake valves or exhaust valves of some cylinders are deactivated during low or medium loads, and the intake valves or exhaust valves of all cylinders are activated during high loads, fuel efficiency can be improved. It is hoped that this will improve.

In this way, efficiency is increased over the entire operating range of the engine by selectively operating or stopping some of the intake valves and exhaust valves that have the same function. It is possible to improve fuel efficiency. Therefore, as disclosed in Japanese Utility Model Application No. 57-193905, by switching the connection and disconnection between the cam follower, which is swing-driven by the cam, and the valve lifter, which is interlocked and connected to the valve, the valve A device has already been proposed in which the activation and deactivation of the device can be switched.

By the way, switching between coupling and disconnection of the cam follower and the valve lifter needs to be performed in a state where the relatively swingable cam follower and the valve lifter are in the same phase. However, if the switching operation is started in the middle of the period when the cam follower and the valve lifter are in the same phase, the cam follower will be pressed by the higher part of the cam and start rocking motion before the switching operation is completed, causing the switching to fail. Although the operation may not be performed smoothly, the above-mentioned prior art does not disclose such a configuration.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a valve operating device for an internal combustion engine that allows smooth and reliable switching operations for connecting and disconnecting a cam follower and a valve lifter. shall be.

In order to achieve this object, according to the present invention, the actuation switching device swings in conjunction with the swinging motion of the cam follower and the drive rod connected to the linking member to drive the linking member. and a trigger lever, the drive rod being engaged with the trigger lever to release the engaged state in response to the cam follower sliding into contact with the upper portion of the cam when the connecting member is in the operating position. A notched groove is provided, and the notched groove engages with the trigger lever in order to release the engaged state in response to the cam follower slidingly contacting the higher portion of the cam when the connecting member is in the non-operating position. is provided.

An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 1, a piston 3 is fitted into a cylinder 2 of an internal combustion engine 1 so as to be able to reciprocate, and a cylinder head on the cylinder 2 has a plurality of intake ports each communicating with a plurality of intake passages 4. 4' and a plurality of exhaust ports 6' communicating with the plurality of exhaust passages 6 are formed to open toward the combustion chamber. Each intake port 4' has an intake valve 5.
are respectively disposed, and an exhaust valve 7 is disposed at each exhaust port 6', but at least one of the plurality of intake valves 5 and at least one of the plurality of exhaust valves 7 are , and is configured to be selectively activated or deactivated depending on the rotational speed of the engine 1, and the figure shows an intake valve 5 and an exhaust valve configured in this manner. 7 is shown.

The intake valve 5 and the exhaust valve 7 are constantly biased in the direction of closing the corresponding intake port 4' and exhaust port 6' due to the action of the corresponding valve springs 8 and 9, but the corresponding rocker arm The valve lifters 12 and 13 are pivotably supported around the shafts 10 and 11, and
When a pressing force is applied in the axial direction through the adjusting screws 16 and 17 fixed by nuts 14 and 15 at the tips of the arms 3 and 3, the valve springs 8 and 9 move in the axial direction against the elastic force of the valve springs 8 and 9. move to open the corresponding intake ports 4' and exhaust ports 6', respectively.

Each valve lifter 12, 13 is connected to a corresponding cam via a cam follower 18, 19 which is pivotably supported around a corresponding rocker arm shaft 10, 11, independently of these valve lifters 12, 13. 28', 28.
The cams 28', 28 each have a lower portion 29', 29 formed by a circumferential surface on a reference circle, and a higher portion 3 that bulges outward in the radial direction from the reference circle.
0', 30, and these cams 28', 28 are configured to rotate around a common axis in synchronization with the rotation of the engine 1.

Each valve lifter 12, 13 is selectively connected to a corresponding cam follower 18, 19 according to the rotational speed of the engine 1 by a corresponding operation switching device A', A as described later, and these operation switching devices
When A', A is in the operating position, cams 28', 2
The rocking motion of the cam followers 18 and 19 driven by the valve lifters 12 and 13 is transmitted to the valve lifters 12 and 13.
When the actuation switching devices A', A are in the inoperative position, the rocking movement of the cam followers 18, 19 is not transmitted to the valve lifters 12, 13.

Each operation switching device A', A is pivotally supported around a corresponding pivot shaft 20, 21, respectively, and is in sliding contact with each cam driven body 18, 19, so that each cam driven body 18, The trigger lever 22, 23 swings in conjunction with the swinging motion of the trigger lever 19, and the drive rods 24, 25 are reciprocated in the axial direction by an actuator 32 (see FIG. 2a).
When the drive rods 24, 25 are in the operating position, the trigger levers 22, 23 engage the valve actuation notches 2 formed in the corresponding drive rods 24, 25.
6, 27 locks the drive rods 24, 25 in the actuated position, and when the drive rods 24, 25 are in the inoperative position, each trigger lever 22, 23 locks the drive rod 24, 25 in the actuated position. Notch groove 3 for valve stop formed in 24, 25
4 (see FIG. 2a) to lock the drive rods 24, 25 in the inoperative position.

The operation switching device A' on the intake valve 5 side and the operation switching device A on the exhaust valve 7 side basically have the same configuration and function as each other. The operation switching device A will be explained in more detail.

In FIGS. 2a, b, and c, the drive rod 25, which is reciprocated in the axial direction by the actuator 32, is constantly moved in the retracting direction (second direction) by the return spring 33.
When the actuator 32 is placed in the operating state, the actuator 32 receives a biasing force in the protrusion direction (upward in FIG. 2a), causing the return spring 33 to Move in the same direction against the rebound force. And actuator 3
2 is placed in the inoperative state, the driving rod 25 is moved in the retracting direction again by the resilient force of the return spring 33.

The drive rod 25 has a valve actuation notch groove 27 extending from the base end on the actuator 32 side toward the distal end side.
A notch groove 34 for stopping the valve is sequentially formed, and furthermore, on the distal side of the notch groove 34 for stopping the valve, there is a part of the shift fork 37 that is swingably supported around the pivot shaft 36. side fork 38,3
8' is formed with a notch engaging portion 35 that engages so as to create an axial play X. Moreover, the clearance X is set smaller than the interval between the valve actuation notch groove 27 and the valve deactivation notch groove 34. The forked portion 39 on the other side of the shift fork 37,
39' is swingably engaged with engaging portions 41, 41' formed on the outer peripheral surface of the cylindrical portion of the shifter 40, which is fitted to the rocker arm shaft 11 so as to be slidable in the axial direction.

A base end portion of a shifter pin 43 serving as a connecting member parallel to the rocker arm shaft 11 and the drive rod 25 is connected to the flange portion 42 of the shifter 40 . It is fitted into the guide hole 44 so as to be slidable in the axial direction. Further, a socket hole 45 is formed in a portion of the base of the cam follower 19 facing the guide hole 44, into which the tip of the shifter pin 43 can freely engage and disengage.

In particular, as shown in FIG. 2b, a resilient spring 46 is interposed between a spring seat 13' formed on the valve lifter 13 side and a spring seat 19' formed on the cam follower 19 side. This spring 4
6, the tip end surface of the adjusting screw 17 is always in contact with the tip end surface of the valve stem of the exhaust valve 7 to such an extent that there is no gap, and the sliding contact portion 31 of the cam follower 19 with respect to the cam 28 is in contact with the cam of the cam 28. The valve lifter 13 and the cam follower 19 are urged in directions that repel each other so as to be in sliding contact with the surfaces to such an extent that there is no gap at all times.

While the sliding portion 31 of the cam follower 19 is in sliding contact with the lower portion 29 of the cam 28 as the cam 28 rotates, the other end of the trigger lever 23 whose one end is in contact with the cam follower 19 The notch groove 27 for valve actuation corresponds to the axial movement position of the drive rod 25.
Alternatively, it engages with the valve stop notch groove 34, and
When the sliding contact portion 31 of the cam follower 19 slides against the high portion 30 of the cam 28, the trigger lever 23 is pressed by the cam follower 19 and is swung counterclockwise in FIG. 2b until it is engaged. It separates from the notch groove 27 for valve operation or the notch groove 34 for valve deactivation that was fitted.

When the actuator 32 is in a non-operating state, the drive rod 25 is in the retracted position, that is, the valve rest position, by the action of the return spring 33, and at this time the shifter pin 43 is in a retracted position from the socket hole 45, and the cam follower 19 is in a retracted position. The rocking movement is not transmitted to the valve lifter 13. Further, when the actuator 32 is in the operating state, the drive rod 25
When the shifter pin 43 is in the extended position against the return spring 33, that is, in the valve operating position, the shifter pin 43 is engaged in the socket hole 45, and at this time, the swinging motion of the cam follower 19 is transmitted to the valve lifter 13. The exhaust valve 7 opens and closes as the cam 28 rotates.

The switching operation of the operation switching device A will be explained below with reference to FIGS. 3a, b to 7a, b.
First, in FIGS. 3a and 3b, the actuator 32
When the sliding part 31 of the cam follower 19 comes into sliding contact with the high part 30 of the cam 28 while the drive rod 25 is in the operating state and receiving a pressing force in the direction in which the drive rod 25 protrudes, the trigger lever 23 is moved to the cam follower. By being pressed and swung by the body 19, it is separated from the valve stop notch groove 34. As a result, the drive rod 25
is extended by the clearance X between the notch engaging portion 35 and the forked portion 38 of the shift fork 37, but at this time the guide hole 44 and the socket hole 45 are not yet aligned, so the shifter pin 43 is socket hole 4
5. Do not intervene. In this state, drive rod 25
The intermediate portion between the valve stop notch groove 34 and the valve actuation notch groove 27 is located at a position corresponding to the trigger lever 23, and the trigger lever 23 is engaged with both the notch grooves 34 and 27. do not. Eventually, as shown in FIGS. 4a and 4b, the cam follower 19
When the sliding contact portion 31 of the valve lifter 13 slides against the lower portion 29 of the cam 28, the guide hole 44 of the valve lifter 13 and the socket hole 45 of the cam follower 19 are aligned, and as a result, the shifter pin 43 is pressed by the shifter 40 and the cam slides. While engaging the socket hole 45 of the moving body 19,
The trigger lever 23 comes into engagement with the valve actuating notch 27 of the drive rod 25. Thereafter, as shown in FIGS. 5a and 5b, as the cam 28 rotates, the trigger lever 23 intermittently engages with the valve actuation notch 27 and locks the drive rod 25 in the operating position. During this period, the movement of the cam 28 is transmitted to the exhaust valve 7 via the cam follower 19 and the valve lifter 13, so that the exhaust valve 7 opens and closes in synchronization with the rotation of the engine 1.

Next, when the actuator 32 is placed in the non-operating state in the operating state shown in FIGS. . At this time,
As long as the sliding portion 31 of the cam follower 19 is in sliding contact with the lower portion 29 of the cam 28, the trigger lever 23 is engaged with the valve actuating notch 27 of the drive rod 25. As shown in FIG.
When the trigger lever 23 comes into sliding contact with the high part 30 of the cam 28, the trigger lever 23 is pressed by the cam follower 19 and swings, so that the trigger lever 23 opens the notch groove for valve actuation as shown in FIGS. 6a and 6b. Leaving from 27. In this state, since the valve lifter 13 is receiving a strong repulsive force from the valve spring 9, a strong frictional resistance is generated on the shifter pin 43 that spans the valve lifter 13 and the cam follower 19, and the shifter pin 43 is easily It does not come off from the socket hole 45. Therefore, the drive rod 25 under the action of the return spring 33 is first moved by the axial clearance X between the notch engaging portion 35 and the forked portions 38, 38' of the shift fork 37; The trigger lever 23 moves in the retracting direction until it reaches a position corresponding to the intermediate portion between the valve actuation notch groove 27 and the valve deactivation notch groove 34.

Next, as the cam 28 rotates, the sliding contact part 31 of the cam follower 19 changes its sliding contact position from the high part 30 of the cam 28 to the low part 29, and the cam follower 19 swings. As a result, the reaction force of the valve spring 9 is weakened, and the frictional resistance against the shifter pin 43 is also reduced, so that the shifter pin 43 is removed from the socket hole 45 of the cam follower 19, as shown in FIG. 7a, and the drive rod is removed. 25 is retracted, and as shown in FIGS.
4. Thereafter, as the cam 28 rotates, the trigger lever 23 swings and engages intermittently with the valve stop notch 34 to stop the drive rod 2.
5 is locked in the inoperative position, during which the oscillating movement of the cam follower 19 is not transmitted to the valve lifter 13 and the exhaust valve 7 is at rest.

In this manner, no matter when the actuator 32 is switched between actuation and non-operation in order to switch between the actuating position and the non-actuating position in the actuation switching device A, the shifter pin 43 is started, and a smooth switching operation can be realized at all times.

The adjustment screw 17 is connected to the sliding contact portion 31 of the cam follower 19.
It is adjusted so that the guide hole 44 of the valve lifter 13 and the socket hole 45 of the cam follower 19 are aligned when the valve lifter slides into contact with the lower part 29 of the cam 28. Once adjusted, the nut 15 It is fixed to the valve lifter 13.

As described above, according to the present invention, the operation switching device connects the drive rod connected to the connecting member to drive the connecting member and the trigger lever that swings in conjunction with the swinging movement of the cam follower. The drive rod has a cutout groove that engages with the trigger lever to release the engagement state when the cam follower slides into contact with the upper part of the cam when the coupling member is in the operating position. At the same time, a cutout groove is provided that engages with the trigger lever to release the engaged state in response to the cam follower slidingly contacting the high portion of the cam when the coupling member is in the non-operating position. , the drive rod can move while the cam follower is in sliding contact with the higher part of the cam, and therefore the switching operation of the operation switching device starts when the cam follower starts to come into sliding contact with the lower part of the cam. The switching operation can be started smoothly and reliably.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of an internal combustion engine equipped with a valve train according to an embodiment of the present invention, and FIG. figure,
Fig. 2b is a cross-sectional view of the main part of the valve train taken along line bb in Fig. 2a, and Fig. 2c is a sectional view taken along line c-b in Fig. 2a.
3a is a sectional view of the main part of the valve train taken along line c, FIG. 3a is a sectional view of the main part of the valve train in a state different from that shown in FIG. 3A is a sectional view of the main parts of the valve train in the state shown in FIG. 2B, and FIG. Partial sectional view, 4th
Figure b is a sectional view of the main parts of the valve train in the state shown in Figure 4a, corresponding to Figure 2b, and Figure 5a is Figure 2a of the valve train in a state that is even different from Figure 4a. 5b is a sectional view of the main part corresponding to FIG. 2b of the valve train in the state of FIG. 5a,
Fig. 6a is a cross-sectional view of the main part corresponding to Fig. 2a of the valve train in a state further different from Fig. 5a, Fig. 6b
is a sectional view of the main part corresponding to FIG. 2b of the valve train in the state of FIG. 6a, and FIG. 7a corresponds to FIG. 2a of the valve train in a state further different from FIG. 6a. FIG. 7b is a sectional view of the main part corresponding to FIG. 2b of the valve train in the state of FIG. 7a. 1...Internal combustion engine, 5...Intake valve, 7...Exhaust valve, 10, 11...Rotsuka armshaft, 1
2, 13... Valve lifter, 18, 19... Cam follower, 22, 23... Trigger lever as a trigger member, 24, 25... Drive rod, 26, 2
7, 34... Notch groove, 28, 28'... Cam,
29, 29'...low part, 30, 30'...high part, 43...shifter pin as a connecting member, A,
A'...Action switching device.

Claims (1)

[Claims] 1 Low part 2 formed by the circumferential surface on the reference circle
9, 29' and high portions 30, 30' that protrude outward in the radial direction from the lower portions 29, 29'. cam driven bodies 18, 19, which are independently pivoted to the rocker arm shafts 10, 11, and a valve lifter 12, which is interlocked and connected to the intake valve 5 or the exhaust valve 7; 13 and cam follower 1
8, 19 and valve lifters 12, 13, and a non-operating position where the connection is released, the position of the connecting member 43 can be changed according to the rotational speed of the engine 1. In the valve operating system for an internal combustion engine, the operation switching devices A, A' are connected to the drive rods 24, 25 connected to the connecting member 43 to drive the connecting member 43.
and trigger levers 22, 23 that swing in conjunction with the swinging motion of the cam followers 18, 19, and the drive rods 24, 25 have cams 28, 28' high part 30,
When the cam followers 18 and 19 come into sliding contact with the trigger lever 2, the engagement state is released.
Notch grooves 26, 27 are provided to engage the cams 2, 23, and the cam followers 18, 19 slide on the high parts 30, 30' of the cams 28, 28' when the connecting member 43 is in the non-operating position. A valve train for an internal combustion engine, characterized in that a notch groove 34 is provided that engages the trigger levers 22 and 23 to release the engaged state when the trigger levers 22 and 23 contact each other.