JPH0239606B2 - - Google Patents

Description

Detailed Description of the Invention A. Purpose of the Invention (1) Industrial Field of Application The present invention applies to an intake valve or an exhaust valve in order to open the intake valve or exhaust valve which is biased in the valve opening direction. A plurality of contactable cam followers are pivotally supported on the shaft, and a cam for swinging each of the cam followers is integrated into the cam follower, which is rotatably driven in synchronization with the rotation of the engine. The present invention relates to a valve operating system for an internal combustion engine that is provided with a valve operation changing mechanism that includes a connecting member that is movable between a position where each cam follower is connected and a position where the connection is released.

(2) Prior art Conventionally, the above-mentioned valve train has been proposed by the present applicant (Japanese Patent Application No. 100505/1982)
226216), when the engine is running at low speed, the locker arm as a cam follower is released from the locker arm connection state and only one intake valve or exhaust valve is opened/closed by the deactivation mechanism, and when the engine is running at high speed, the deactivation mechanism is activated. Both rocker arms are connected to open and close both intake valves or exhaust valves, and tappet screws are screwed into the contact portions of both rocker arms with the intake valve or exhaust valve so that they can move forward and backward.

(3) Problems to be Solved by the Invention In the above-mentioned conventional valve train, when the intake valve or exhaust valve is closed, there is a gap between the tappet screws of both rocker arms and both intake valves or both exhaust valves. There may be a gap between the two rocker arms, and the tappet screw will come into contact with the intake valve or the exhaust valve in response to the rocking motion of both rocker arms. For this reason, a striking sound is generated when the tappet screw comes into contact with the intake valve or exhaust valve, and in order to maintain proper operation at all times, the threading amount of the tappet screw must be adjusted according to wear of the tappet screw. It was necessary to do this. In addition, the pistons connect both rocker arms when both rocker arms are in the closed state, but when the valves are in the closed state, the position of each rocker arm becomes unstable, making it difficult for the engine that is not in operation to operate smoothly. There is a possibility that it will no longer be possible.

The present invention has been made in view of the above circumstances, and by bringing each cam follower into constant elastic contact with the intake valve or exhaust valve, accurate and quiet valve operation is always realized without the need for adjustment operations. It is an object of the present invention to provide a valve operating system for an internal combustion engine that enables reliable connection operation of an operation stop mechanism.

B. Structure of the Invention (1) Means for Solving the Problems According to the present invention, in order to achieve the above object, an intake valve that is biased in the valve closing direction or an exhaust valve that is biased in the valve closing direction is opened. Alternatively, a plurality of cam followers that can come into contact with the exhaust valve are pivotally supported on a shaft, and a cam for swinging each of the cam followers is integrated into the camshaft which is rotationally driven in synchronization with the rotation of the engine. In a valve operating system for an internal combustion engine, the cam follower is provided with a valve operation changing mechanism that includes a connecting member that is movable between a position where each cam follower is connected and a position where the connection is released by the action of hydraulic pressure. are commonly pivotally supported on a first shaft, and the first shaft is fixed to an adjustment arm that is swingably supported on a second shaft that is fixed to the engine body. An oil tappet is provided separately from the valve operation changing mechanism, and elastically supports the adjusting arm so as to urge the adjusting arm to rotate in the direction of abutting the intake valve or the exhaust valve about the point of contact with the adjusting arm as a fulcrum.

(2) Function Each cam follower is rotated in the direction of contacting the intake valve or exhaust valve by the action of the oil tappet, and each cam follower always resiliently contacts the intake valve or exhaust valve.

(3) Embodiments Below, embodiments of the present invention will be explained with reference to the drawings.
In the figures and FIG. 3, a pair of intake valves V1 and V2 provided in the engine body 1 are connected to a cam integrally provided on a camshaft 2 that is driven at a rotation ratio of 1/2 in synchronization with the rotation of the engine. C, first and second rocker arms 3 and 4 as cam followers that can freely swing around an axis parallel to the camshaft 2, and a valve operation changing mechanism 5 provided on both rocker arms 3 and 4.
The opening and closing operation is performed by switching between a state in which both intake valves V1 and V2 are opened and closed, and a state in which only one intake valve V1 is opened and closed. The engine body 1 is also equipped with a pair of exhaust valves (not shown), and these exhaust valves are also connected to the aforementioned intake valves V1 and V.
It is opened and closed in the same way as 2.

The camshaft 2 is rotatably disposed above the engine body 1, and the cam C is integrally provided on the camshaft 2 at a position corresponding to one intake valve V1. Further, a concentric raised portion 6 is integrally provided on the camshaft 2 at a position relative to the other intake valve V2, and the radius of this raised portion 6 is set to be the same as the radius of the base circle 7 of the cam C. Furthermore, a cam slipper 8 is integrally provided at the upper center of the first rocker arm 3 and slides on the cam C.
A slipper 9 that can slide into the raised portion 6 is integrally provided at the upper center of the rocker arm 4. When the first and second rocker arms 3, 4 are capable of relative angular displacement, the raised portion 6 is in sliding contact with the slipper 9;
It functions to suppress the second rocker arm 4 from jumping up and keep the second rocker arm 4 in a stationary state.

The bases of the rocker arms 3 and 4 are commonly pivotally supported by a first rocker shaft 10 as a first shaft parallel to the camshaft 2, and the first rocker shaft 10 is fixed to the end of the adjustment arm 11. Furthermore, the base of the adjustment arm 11 is connected to the engine body 1.
The lock shaft 10 is fixedly disposed on the shaft 10, and is pivotally supported by a second rock shaft 12, which is a second shaft parallel to the first rock shaft 10. A receiving portion 13 extending downward from the first rocker shaft 10 is integrally provided at the base of the adjustment arm 11 .

The engine body 1 has a receiving part 13 for the adjustment arm 11.
An oil tappet 14 is provided to resiliently support the. This oil tappet 14 has a conventionally well-known structure, and has a bottomed cylindrical cylinder 1.
5, a plunger 17 that is slid into the cylinder 15 and defines an oil reservoir chamber 16, a hydraulic chamber 18 defined between the plunger 17 and the bottom of the cylinder 15, and a spring accommodated in the hydraulic chamber 18. 19
and a check valve 20 disposed between the oil reservoir chamber 16 and the hydraulic chamber 18.

The cylinder 15 is inserted into the engine body 1 with its open end facing upward. The plunger 17 has a spherical end 2
The plunger 17 is slidably movable vertically into the cylinder 15 with the plunger 1 facing upward, and a valve hole 22 is formed in the lower part of the plunger 17. Further, the oil reservoir chamber 16 is always in communication with an oil supply source (not shown), and therefore the oil reservoir chamber 16 is always filled with hydraulic oil.

A plunger 17 is installed in the hydraulic chamber 18 by a spring 19.
A spherical check valve 20 is housed in the valve cage 23 in a floating manner.

In such an oil tappet 14, the plunger 17 is biased by a spring 19 so as to bring its spherical end 21 into contact with the receiving part 13 of the adjusting arm 11, so that the adjusting arm 11 is elastically moved by the plunger 17. supported by. Moreover, when the pressure in the hydraulic chamber 18 decreases as the plunger 17 rises, the check valve 20 opens and the hydraulic oil from the oil reservoir chamber 16 flows into the hydraulic chamber 18. Even if a pressing force is applied, the plunger 17 is prevented from descending, and the adjusting arm 11
is stably supported.

At the end of each rocker arm 3, 4 there is an intake valve V1,
Contact portions 24 and 25 for contacting the upper end of V2 are provided, respectively, and these contact portions 24,
25 is biased in the direction of contacting the upper ends of the intake valves V1 and V2. That is, since the adjustment arm 11 is elastically pushed up by the oil tappet 14, the first rocker shaft 10 is also pushed upward. Therefore, the first rocker arm 3 rotates around the contact position between the cam slipper 8 and the cam C in a direction in which the contact portion 24 contacts the intake valve V1, and the second rocker arm 4 rotates between the slipper 9 and the raised portion 6.
The abutment portion 25 is connected to the intake valve V with the abutment position as a fulcrum point.
Rotate in the direction of contacting 2.

Here, due to dimensional errors during initial assembly of the first and second rocker arms 3, 4, wear, and changes over time due to thermal expansion, one of the contact portions 24, 25 may come into contact with one of the intake valves V1, V2. Although they are in contact with each other, the other of the contact portions 24 and 25 is connected to the intake valves V1 and V.
There is a possibility that a situation may occur in which the other one of the parts 2 and 2 does not come into contact with each other. Therefore, at least one of the contact parts 24 and 25, in this embodiment, the contact part 25 of the second rocker arm 4 is provided with a plunger 26 for absorbing the above-mentioned deviation.

A bottomed hole 27 that is open to the intake valve V2 side is bored in the contact portion 25, and a stepped portion 28 that faces the open end side is provided in the middle of this bottomed hole 27.
The plunger 26 has a stepped portion 28 and a bottomed hole 27.
The ring 29 is fitted into the inner surface of the open end of the ring 29, and the ring 29 is slidably fitted into the bottomed hole 27. A hydraulic chamber 30 is defined by the plunger 26 and the closed end side of the bottomed hole 27.
A spring 3 biases the intake valve V2 in the direction of contacting the intake valve V2.
1 is accommodated.

Further, an oil passage 32 communicating with the hydraulic chamber 30 is bored in the second rocker arm 4, and the first rocker shaft 10
An oil passage 33 is provided inside. A through hole 34 is bored in the side wall of the first rock shaft 10 to allow the oil passage 33 to communicate with the oil passage 32.
A check valve 35 is interposed between the oil passage 33 and the oil passage 32 to allow hydraulic oil to flow only from the oil passage 33 to the oil passage 32. Furthermore, an oil passage 37 is bored in the adjustment arm 11 and communicates with the oil passage 33 through a through hole 36 bored in the side wall of the first rocker shaft 10.
communicates with an oil passage 39 in the second rocker shaft 12 via a through hole 38 bored in the side wall of the second rocker shaft 12. This oil passage 39 is connected to an oil supply source (not shown).

A throttle 40 that communicates with the hydraulic chamber 30 is bored in the upper part of the contact part 25, and this throttle 40 limits the speed of discharge from the hydraulic chamber 30 and prevents air from entering the hydraulic chamber 30. It also functions to expel air.

On the other hand, the upper part of both intake valves V1 and V2 has a flange 4.
1 and 42 are provided, and these collar parts 41,
42 and the engine body 1, there are intake valves V1 and V2.
Valve springs S1 and S2 surrounding the are interposed,
Each intake valve V1, V2 is biased toward the valve closing direction, that is, upward, by valve springs S1, S2.

In FIG. 4, the first and second rocker arms 3, 4 are in sliding contact with each other, allowing relative angular displacement, and both rocker arms 3,
Both rocker arms 3 and 4 are provided with a valve operation changing mechanism 5 that can switch between a state in which the two rocker arms 4 are integrally connected.

The valve operation changing mechanism 5 includes a piston 51 as a connecting member that is movable along an axis parallel to the first rocker shaft 10 between a position where both rocker arms 3 and 4 are connected and a position where the connected state is released.
, a stopper 52 that restricts the movement of the piston 51, and a spring 53 that biases the stopper 52 to move the piston 51 toward the disconnection position.

The first locking arm 3 has a second locking arm 4.
A first guide hole 54 is bored that is open toward the side and parallel to the first rocker shaft 10, and a small diameter portion 56 is provided at the bottom of the first guide hole 54 via a stepped portion 55. First guide hole 5
A piston 51 is slidably connected to the first guide hole 54 , thereby defining a hydraulic chamber 57 between the piston 51 and the bottom surface of the first guide hole 54 . Further, an oil passage 58 communicating with the hydraulic chamber 57 is bored in the first rocker arm 3, and this oil passage 58 is connected to the inside of the first rocker shaft 10 through a through hole 59 bored in the side wall of the first rocker shaft 10. It is always in communication with the oil passage 33.

The axial length of the piston 51 is set so that when one end thereof contacts the stepped portion 55, the other end does not protrude from the side surface of the first rocker arm 3 facing the first rocker arm 4 side.

The second locking arm 4 has the first locking arm 3.
The first guide hole 5 corresponds to the first guide hole 54 of
A second guide hole 60 having the same diameter as the first rocker arm 3 is opened and opened toward the first rocker arm 3 side, and a disc-shaped stopper 52 is slid into this second guide hole 60. A small diameter portion 62 is provided on the bottom side of the second guide hole 60 via a regulating step portion 61 . Also, the second guide hole 6
A small-diameter insertion hole 63 that is concentric with the second guide hole 60 is bored in the second rocker arm 4 between the bottom and the outer surface of the stopper 52, and is provided integrally and concentrically with the stopper 52. A small diameter guide rod 64 is inserted into the insertion hole 63. Furthermore, the stopper 52
A guide rod 6 is provided between the bottom surface of the second guide hole 60 and the bottom of the second guide hole 60.
A coiled spring 53 surrounding 4 is interposed.

In such a valve operation changing mechanism 5, the first and second guide holes 54, 60 are such that the cam slipper 8 of the first rocker arm 3 slides on the base circle 7 of the cam C, and the slipper 9 of the second rocker arm 4 is raised. It is determined to be concentric when it is in sliding contact with part 6.

Next, the operation of this embodiment will be explained. When the engine is operated at low speed, relatively low pressure hydraulic oil is supplied to the hydraulic chamber 57 of the valve operation changing mechanism 5. As a result, the stopper 52 is pushed toward the first rocker arm 3 by the spring 53, and the piston 51 is pushed toward the step portion 5.
5. In this state, the contact surfaces of the piston 51 and the stopper 52 are at positions corresponding to the sliding surfaces of the first and second rocker arms 3 and 4. Therefore, the first and second rocker arms 3 and 4 are in sliding contact with each other, and the piston 51 and the stopper 52 are in sliding contact so that relative angular displacement is possible.

In such a disconnected state of the valve operation changing mechanism 5, the rotation of the camshaft 2 causes the first
The rocker arm 3 is oscillated by the cam C, and one intake valve V1 is opened and closed at a timing and lift amount depending on the shape of the cam C. On the other hand, the slipper 9 of the second rocker arm 4 is in sliding contact with the raised portion 6, and the other intake valve V2 remains closed.

When operating the engine at high speed, the valve operation changing mechanism 5
Relatively high pressure hydraulic oil is supplied to the hydraulic chamber 57 of. As a result, the piston 51 moves into the second guide hole 60 while compressing the spring 53 until the stopper 52 comes into contact with the restriction step 61, and the piston 51 connects the first and second rocker arms 3 and 4.

In this way, the first and second rocker arms 3,
4 are integrally connected, both the first and second rocker arms 3 and 4 swing according to the rotation of the cam C, and both the intake valves V1 and V2 are opened and closed.

Further, the adjustment arm 11 is supported by an oil tappet 14 with an upward elastic force, and the cam slipper 8 of the first rocker arm 3 is in sliding contact with the cam C on the first rocker shaft 10, and the slipper of the second rocker arm 4 is in sliding contact with the cam C. 9 is in sliding contact with the raised portion 6, and as a result, the contact portions 24, 25 of each rocker arm 3, 4 rotate in the direction of contacting the intake valves V1, V2. It is dynamically energized. Moreover, a plunger 26 is provided on the contact portion 25 of the second rocker arm 4, and this plunger 26 is biased by a spring in the direction of contacting the intake valve V2, so that the contact portion 24 contacts the intake valve V1. Before contacting the intake valve V2, the plunger 26 contacts the intake valve V2, but when the plunger 26 contacts the intake valve V2, the plunger 26
The spring 31 retreats while contracting the spring 31, and its retreating speed becomes gentle because the speed of draining oil from the hydraulic chamber 30 is limited by the throttle 40, so that the impact when it comes into contact with the intake valve V2 is alleviated. Ru.

Both locking arms 3 with oil tappets 14,
4 ends when the contact portion 24 of the first rocker arm 3 contacts the intake valve V1, and at this point both rocker arms 3 and 4 contact the intake valves V1 and V2. Moreover, since the plunger 26 can freely move back and forth, dimensional errors during initial assembly of the two rocker arms 3 and 4 and changes over time due to wear, thermal expansion, etc. can be absorbed by the forward and backward movement of the plunger 26. It is possible to maintain a state in which the valves are always in contact with the intake valves V1 and V2 without leaving a gap. Therefore, it is possible to achieve proper and quiet operation of the valve train.

FIG. 5 shows the main part of an embodiment of the present invention, and shows the orifice 40 of the hydraulic chamber 30 in the embodiment described above.
The check valve 35 and the check valve 35 are omitted, and a throttle 40' is provided in the middle of the oil passage 32 instead. Even with such a simple structure, it is possible to limit the speed of draining oil from the hydraulic chamber 30 and reduce the impact when the plunger 26 comes into contact with the intake valve V2.

Further, the plunger 26 may be provided on at least one of the contact parts 24 and 25, but in order to avoid wear of the plunger 26, the contact part 26 of the second rocker arm 4, which stops operating during low speed operation, It is preferable that the

In the above explanation, only the portions related to the intake valves V1 and V2 have been described, but the pair of exhaust valves are also operated in the same manner as the intake valves V1 and V2. Furthermore, the valve operating system of the present invention may be provided in connection with only one of the intake valves V1 and V2 and the pair of exhaust valves.

C. Effects of the Invention As described above, according to the present invention, in order to open the intake valve or exhaust valve that is biased in the valve-closing direction,
A plurality of cam followers that can come into contact with the intake valve or the exhaust valve are pivotally supported on a shaft, and a cam for swinging the cam followers is integrated into the camshaft that is rotationally driven in synchronization with the rotation of the engine,
In the valve operating system for an internal combustion engine, the cam follower is provided with a valve operation changing mechanism that includes a connecting member that is movable between a position where each cam follower is connected and a position where the connection is released by the action of hydraulic pressure. The cam followers are commonly pivotally supported on a first shaft, and the first shaft is fixed to an adjustment arm that is swingably supported on a second shaft that is fixed to the engine body. An oil tappet that elastically supports the adjustment arm so as to rotate and bias the adjustment arm in the direction of contacting the intake valve or the exhaust valve using the contact point with the camshaft as a fulcrum is provided separately from the valve operation changing mechanism. Each cam follower can always be brought into elastic contact with the intake valve or exhaust valve without the need for special adjustment operations, so it can always be accurately and quietly regardless of the operating state of the valve operation changing mechanism. It is possible to realize a valve train operation that is easy to operate. Moreover, since the position of the cam follower can always be stabilized when the intake valve or exhaust valve is in the open state, the transition to the connected state of the valve operation changing mechanism that is executed in the closed state can be made smoothly and reliably. It will be done. Furthermore, by appropriately selecting the contact position of the oil tappet with respect to the adjustment arm, the load to be supported by the oil tappet and the swing displacement angle of the adjustment arm can be easily selected.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, FIG. 1 is a plan view, and FIG. 2 is a -
3 is a sectional view taken along the - line in FIG. 1, FIG. 4 is a sectional view taken along the - line in FIG. 3, and FIG. 5 is a longitudinal sectional view of a main part of another embodiment of the present invention. 1... Engine body, 2... Camshaft, 3, 4
...Lotsuka arm as a come follower, 5...
Valve operation changing mechanism, 10... First rock shaft as a first shaft, 11... Adjustment arm, 12
...Second rotary shaft as the second shaft,
14... Oil tappet, 24, 25... Contact portion, 26... Plunger, 30... Hydraulic chamber, 51
... Piston as a connecting member, C ... Cam, V
1, V2...Intake valve.

Claims (1)

[Claims] 1. In order to open the intake valves V1, V2 or the exhaust valves which are biased in the valve closing direction, the intake valves V1, V2
Alternatively, a plurality of cam followers 3 and 4 that can come into contact with the exhaust valve are pivotally supported on a shaft 10, and a cam shaft 2 that is rotatably driven in synchronization with the rotation of the engine has a cam for swingingly driving each of the cam followers 3 and 4. C is integrated, and each cam follower 3, 4 is provided with a connecting member 51 that is movable between a position where each cam follower 3, 4 is connected and a position where the connection is released by the action of hydraulic pressure. Mechanism 5
In a valve train for an internal combustion engine, each of the cam followers 3 and 4 is commonly pivotally supported by a first shaft 10, and the first shaft 10 is swingable on a second shaft 12 fixed to the engine body. The cam followers 3 and 4 are fixed to the adjustment arm 11 which is pivotally supported by the engine body 1, and are biased to rotate in the direction in which each cam follower 3, 4 comes into contact with the intake valves V1, V2 or the exhaust valve using the contact point with the camshaft 2 as a fulcrum. an oil tappet 14 that resiliently supports the adjustment arm 11;
is provided separately from the valve operation changing mechanism 5. A valve operating system for an internal combustion engine. 2 Intake valves V1 and V of each of the cam followers 3 and 4
2 or at least one of the contact parts with the exhaust valve has one end facing the hydraulic chamber 30 where the oil drainage speed is restricted, and the other end is biased by a spring in the direction of contacting the intake valves V1, V2 or the exhaust valve. The valve operating system for an internal combustion engine according to claim 1, wherein the plunger 26 is arranged to be movable back and forth.