JPS6397816A - Valve system for interval combustion engine - Google Patents

Abstract

PURPOSE:To smooth the switching action of a coupling and switching mechanism through simple constitution, by a method wherein a timing plate, engaged with a piston in a coupling releasing position to be inhibited against only movement to the coupling position side, is situated so as to allow release of engagement during the action of a cam follower. CONSTITUTION:When an oil pressure is fed to a hydraulic chamber 21 through the working of a piston 11 of a coupling and switching mechanism 8 so as to intercouple two locker arms 6 and 7 serving as a cam follower, the piston 11 is moved from a release position to a coupling position. In this case, when a first locker arm 6 is rotated downward so as to open a suction valve V1, the piston 11 is released from contact with a timing plate 14, and movement of the piston 11 to the second locker arm 7 side. When the first locker arm 6 is rotated upward until the axes of two guide holes 15 and 30 are coincided with each other, the piston 11 is moved to a coupling position allowing the piston to be engaged with the guide hole 30, and the two locker arms 6 and 7 are coupled with each other.

Description

Detailed Description of the Invention A0 Object of the Invention (1) Industrial Field of Application The present invention relates to a method for connecting a plurality of cam followers that respond to a camshaft to open and close an intake valve or an exhaust valve that is biased in the valve-closing direction. The present invention relates to a valve train for an internal combustion engine that is provided with a connection switching mechanism that includes a piston that is movable between a position where the cam followers are connected and a position where the connection is released.

(2) Prior Art Conventionally, in such a valve train, each cam follower must be in an inoperative state when switching the connection state by the connection switching mechanism.

However, if the piston starts moving while each cam follower is not operating, that is, while the intake valve or exhaust valve is closed, the cam follower will start operating before the movement is complete, and the switching of the connected state will be smooth. There are some things that are not done. Therefore, in order to start the movement of the piston toward the connection position and the movement to the disconnection position from the beginning of the period in which the cam follower does not operate, that is, the valve closing period of the intake valve or exhaust valve, it is necessary to Japanese Patent Laid-Open Publication No. 31611/1987 (Japanese Patent Application Laid-Open No. 61-31611) discloses a method in which the valve is engaged with the piston at the time of the valve opening, and the engaged state is released when the cam follower operates in the valve opening direction.

(3) Problems to be Solved by the Invention However, the reason why smooth switching is not achieved by moving the piston is because it takes time to center the cam followers to be connected, so that the piston moves from the uncoupled position to the connected position. Therefore, instead of the conventional method that restricts the movement of the piston in both directions, only the movement of the piston from the uncoupled position to the connected position is restricted. However, the connection switching mechanism can switch the connection state as smoothly as possible.

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 train for an internal combustion engine that has a simple structure and enables smooth operation of a connection switching mechanism.

B0 Structure of the Invention (1) Means for Solving Problems According to the present invention, the timing plate that engages with the piston in the disconnected position and prevents it from moving only toward the connected position is connected to the intake valve or the exhaust valve. The cam follower is disposed so as to be able to release the engaged state when the cam follower operates to open the valve.

(2) The piston in the operational connection release position is allowed to move toward the connection position only when the cam follower operates in the valve opening direction, and therefore the connection switching mechanism starts the connection operation when the cam follower opens the valve. This is the beginning of the valve closing section after the operation in the direction is completed.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, in FIGS. 1 and 2, a pair of intake valves Vl and V2 provided in the engine body l are connected to valve springs St and is biased in the valve closing direction. These intake valves Vl
, V2 is a cam 4 integrally provided with a camshaft 3 that is rotationally driven at a rotation ratio of 1/2 in synchronization with the rotation of the engine.
and 1, first and second cam followers as cam followers pivotably supported on a rocker shaft 5 parallel to the camshaft 3.
Due to the action of the zero hook arm 6.7 and the connection switching mechanism 8 provided between the two hook arms 6 and 7, one intake valve v
The opening and closing operation is performed by switching between a state in which only intake valve i is opened and closed, and a state in which both intake valves Vl and V2 are opened and closed.

The camshaft 3 is rotatably disposed above the engine body l, and the cam 4 is integrally provided on the camshaft 3 at a position corresponding to one intake valve V1. This cam 4 has a base circle 4a concentric with the camshaft 3, and a base circle 4a concentric with the camshaft 3.
It has a high portion 4b that protrudes radially outward from a.

Further, on the camshaft 3, a perfectly circular raised portion 9 having the same diameter as the base circle 4a is integrally provided at a position corresponding to the other intake valve V2.

The rocker shaft 5 is fixedly arranged below the camshaft 3, and includes a tenth hook arm 6 corresponding to one intake valve v1 and a twentieth hook arm corresponding to the other intake valve v2. 7 are supported adjacent to each other for relative angular displacement. In addition, tappet screws Tl and T2 that can abut the upper ends of the intake valves Vl and V2 are screwed into the ends of the double-ended hook arm 6.7 located above the intake valves Vl and V2 so as to be able to move forward and backward. .

A cam slipper 6a that slides on the cam 4 is integrally provided on the upper part of the tenth claw arm 6, and the tenth claw arm 6 swings in accordance with the rotational movement of the cam 4. That is, the tenth hook arm 6 is stationary when its cam slipper 6a is in sliding contact with the base circle 4a of the cam 4, and when the cam slipper 6a comes into sliding contact with the high part 4b, it is compressed while contracting the valve spring Sl. Rotate downward to open the intake valve v1.

Further, the upper part of the 20th linker arm 7 is provided with a sliding contact part 7a that comes into sliding contact with the raised part 9, and this raised part 9 is used when the connection state of the double-end hook arm 6.7 is released, that is, when the intake valve When v2 is in the closed state, it functions to prevent the 20th claw arm 7 from jumping up and maintain a stationary state.

In FIG. 3, a connection switching mechanism 8 for connecting and disconnecting the first and 20th hook arms 6.7 is configured to switch between a position where the double-ended hook arms 6.7 are connected and a position where the connection state is released. It includes a movable piston 11, a stopper 12 that restricts the movement of the piston 11, and a spring 13 that presses the piston 11 toward the disconnection position (that biases the stopper 12).

The 10th hook arm 6 has a first guide hole 15 opened toward the 20th hook arm 7 side and parallel to the rocker shaft 5, and the closed end side of the first guide hole 15 is provided with a 20th hook arm 7. Regulation step 16 facing the hookah arm 7 side
A small diameter portion 17 is provided via the . This first guide hole 1
A piston 11 is slidably connected to the piston 5 .

A hydraulic chamber 21 is defined between the piston 11 and the closed end of the first guide hole 15, and a hydraulic chamber 21 is defined in the tenth hook arm 6.
An oil passage 27 communicating with 1 is bored. Further, a hydraulic pressure supply path 28 is provided in the rocker shaft 5 and is connected to a hydraulic pressure supply source (not shown).
9, the tenth hook arm 6 is always in communication no matter what posture it is in.

A second guide hole 30 corresponding to the first guide hole 15 is bored in the 20th hook arm 7 so as to open toward the 10th hook arm 6 side, and the stopper 12 is slid into this second guide hole 30. 1. The stopper 12 is formed into a disk shape, and is inserted into the second guide hole 30 until it comes into contact with a regulating step 31 provided facing the tenth lever arm 6 at the middle of the second guide hole 30. can be slid. Further, an insertion hole 32 is coaxially formed at the closed end of the second guide hole 30, and a guide shaft portion 33 integrated with the stopper 12 is inserted through the insertion hole 32. Thereby, the stopper 12 slides with its axis always aligned with the axis of the second guide hole 30.

A coiled spring 13 surrounding the guide shaft portion 33 is interposed between the closed end of the second guide hole 30 and the stopper 12, and the stopper 12 uses the spring force of the spring 13 to move the piston 11 into the hydraulic chamber. It is urged in the direction of pressing toward the 21 side.

The piston 11 and the stopper 12 are always in contact with each other,
An annular engagement groove 25 is formed at the end of the stopper 12 on the piston 11 side between the stopper 12 and the piston 11 (a small diameter shaft portion 26 is provided coaxially and protrudingly).

When the piston 11 is in the disconnected position, that is, when the piston 11 is in contact with the restriction step 16, the contact surfaces of the piston 11 and the stopper 12 are in contact with the first and second
It is located at a position corresponding to between the 0 and 7 arms, and the engagement groove 2
5 is also located between the first and 20th claw arms 6.7. In this state, the timing plate 14, which can be held in the engagement groove 25, is rotatably supported on the rocker shaft 5 between the two rocker arms 6.7.

4 and 5, the timing plate 14 includes a disc-shaped base 38 having a hole 41 through which the rocker shaft 5 is inserted, and a disc-shaped base 38 that is connected to the upper part of the base 38 and parallel to the rocker shaft 5. An arm portion 39 extending toward the tenth arm 6 side, and a locking portion 40 extending from the top of the disk portion 38 in the same plane as the disk portion 38 in a direction perpendicular to the arm portion 39.
and is supported on the rocker shaft 5 so as to be swingable between the first and 207th arms 6.7.

The locking portion 40 of the timing plate 14 is capable of engaging with the engagement groove 25, and is provided with a torsion spring 42 that surrounds the tenth latch arm 6 and is interposed between the engine body 1 and the arm portion 39, so that the timing plate 14 can be engaged with the locking portion 40 of the timing plate 14. The plate 14 is biased to rotate in the direction in which the locking portion 40 engages with the engagement groove 25 . In addition, in the engine body 1,
A stopper pin 43 that can abut on the arm portion 39 of the timing plate 14 is implanted, and the arm portion 39 elastically abuts on the stopper pin 43 due to the spring force of the torsion spring 42 .

Moreover, the implantation position of the stopper pin 43 is set such that the locking portion 40 can engage with the engagement groove 25 when the tenth hook arm 6 is in sliding contact with the raised portion 9 and is in a stationary state.

Next, to explain the operation of this embodiment, the hydraulic chamber 21
When hydraulic pressure is not being supplied to the timing plate 1, the piston 11 is at the disconnection position where it is pushed to the maximum extent toward the hydraulic chamber 21 by the stopper 12 biased by the spring 13, and the timing plate 1
4 is in a position where it can be engaged with the engagement groove 25.

In this disconnected state, the 10th latch arm 6 swings in response to the rotational movement of the cam 4, but the 20th latch arm 7 remains stationary in sliding contact with the raised portion 9, and one of the intake valves v
Only 1 opens and closes.

Here, it is assumed that hydraulic pressure is supplied to the hydraulic chamber 21 by the piston 11 to connect the double-ended hook arms 6.7. Due to the action of this oil pressure, the piston 11 attempts to start moving from the disconnected position to the connected position. However, the timing plate 14 is in a state where it can be engaged with the engagement groove 25, and the first
When the rocker arm 6 rotates downward to open the intake valve v1, the timing plate 14 is released from contact with the end face of the piston 11, allowing the piston 11 to move toward the 207th arm 7 side. Therefore, the piston 11 is the stopper 1
While pressing 2, move to the 20th arm 7 side,
Since the axes of the first and second guide holes 15° 33 are deviated, the piston 11 moves only a short distance until it comes into contact with the side surface of the twentieth hook arm 7. In this state, even if the tenth lever arm 6 rotates upward to close the intake valve v1, the locking portion 40 of the timing plate 14 hits the outer surface of the piston 11 due to the slight movement of the piston 11. It only touches and does not engage the piston 11.

In this state, the tenth hook arm 6 is inserted into both guide holes 15.3.
When the piston 11 rotates upward to the position where the axes of
The piston 11 moves to the connecting position where it fits into the guide hole 30, and the double-ended hook arms 6.7 are connected.

That is, no matter what state the tenth link arm 6 is in at the timing when the connection switching mechanism 8 supplies hydraulic pressure to the hydraulic chamber 21 in order to switch the connection state, the piston 11 is activated when the tenth link arm 6 is closed. When the piston 11 rotates in the direction of the valve and starts to stand still, it starts moving from the disconnected position to the connected position, and smooth switching can be achieved without the piston 11 being hit by the 20th lug arm 7. .

In the state where the double-end latch arms 6.7 are connected, the 20th latch arm 7 swings together with the 10th latch arm 6, so that both intake valves Vl and V2 adjust the timing and lift according to the shape of the cam 4. It opens and closes depending on the amount.

Next, when the hydraulic pressure is released from the hydraulic chamber 21 in switching from the connected state to the disconnected state, the piston 11 is pushed by the spring 13 in the direction of leaving the second guide hole 3.0. At this time, if the axes of both guide holes 15 and 30 do not match, the piston 11 will move toward the first guide hole 15 due to the frictional force between the inner surface of the second guide hole 30 and the piston 11.
When the axes of both guide holes 15 and 30 coincide, the first guide hole 15 moves into the first guide hole 15 and returns to the state shown in FIG. 3.

In such a valve operating system, the timing plate 14 only restricts the movement of the piston 11 from the disconnected position to the connected position, and allows smooth operation of the connection switching mechanism 8 with a relatively simple configuration. Further, the timing plate 14 is swingably supported by the rocker shaft 5, and an advantage can also be obtained that the timing plate 14 is not added to the inertial weight of the valve train.

In the above explanation, the intake valve V1. Although the parts related to V2 have been described, the pair of exhaust valves also have intake valves Vl, V
It is operated in the same way as 2.

C1 Effects of the Invention As described above, according to the present invention, the timing plate that engages with the piston in the disconnected position and prevents it from moving only toward the connected position is connected to the cam follower to open the intake valve or the exhaust valve. Since the engagement state can be released when the connection switching mechanism is operated, the switching operation of the connection switching mechanism can be made smooth with a relatively simple configuration.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a plan view showing the arrangement of the rocker arm, and FIG. 2 is a plan view showing the arrangement of the rocker arm.
3 is a sectional view taken along the line ■--■ in FIG. 2, FIG. 4 is a sectional view taken along the IV-rl/line in FIG. 1, and FIG. 5 is an enlarged perspective view of the timing plate. 3...Camshaft, 6.7...Rocker arm as cam follower, 8...Connection switching mechanism, 11...
Piston, 14...Timing plate, Vl, V2...Intake valve riN, 3L knee 4 Fig. 1 Fig. 2

Claims (1)

[Claims] It is movable between a position where the cam followers are connected and a position where the connection state is released between a plurality of cam followers that respond to the camshaft to open and close the intake valve or exhaust valve that is biased in the valve closing direction. In a valve train for an internal combustion engine that is provided with a connection switching mechanism that includes a piston,
A timing plate that engages with the piston in the disconnected position and prevents it from moving only toward the connected position is arranged so that it can be released from the engaged state when the cam follower operates to open the intake valve or the exhaust valve. A valve train for an internal combustion engine, characterized in that: