JPH0239604B2 - NAINENKIKANNODOBENSOCHI - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Field of Application The present invention is directed to a method of applying pressure to an intake valve or an exhaust valve to open the intake valve or the exhaust valve, which is biased in the direction of closing the valve. The present invention relates to a valve operating system for an internal combustion engine, which includes a plurality of cam followers, and a cam integrated with a camshaft that is rotationally driven in synchronization with the rotation of the engine to swing the cam followers.

(2) Prior art Conventionally, the above-mentioned valve train has been proposed by the present applicant (Japanese Patent Application No. 100505/1982)
226216), a tappet screw is screwed into the contact portion of a rocker arm as a cam follower with an intake valve or an exhaust valve so that it can move forward and backward.

(3) Problems to be Solved by the Invention In the conventional valve train described above, 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 is a possibility that a gap may occur, and the tappet screw comes 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. need to be done.

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, it is possible to always achieve quiet and accurate operation without the need for adjustment operations. The object of the present invention is to provide a valve train for an internal combustion engine that has the following features.

B. Structure of the Invention (1) Means for Solving the Problems According to the present invention, each cam follower is commonly pivotally supported by a first shaft, and the first shaft is pivoted by a second shaft fixed to the engine body. The adjustment arm is fixed to a freely pivotable adjustment arm, and the engine body is provided with a resilient force for rotating each cam follower in the direction of contacting the intake valve or the exhaust valve using the contact point with the camshaft as a fulcrum. An oil tappet is provided which supports the bearing.

(2) Operation According to the above configuration, each cam follower is rotated in the direction of contacting the intake valve or the exhaust valve by the action of the oil tappet, and each cam follower always resiliently contacts the intake valve or the 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. C1, C2, and first and second rocker arms 3, 4 as cam followers that are swingable around an axis parallel to the camshaft 2.
It is opened and closed by the action of The engine body 1 is also provided with a pair of exhaust valves (not shown), and these exhaust valves are also opened and closed in the same manner as the intake valves V1 and V2 described above.

The camshaft 2 is rotatably disposed above the engine body 1, and the cam C1 is connected to one intake valve V1.
The camshaft 2 is provided integrally with the camshaft 2 at a position corresponding to the camshaft 2. Further, the cam C2 is integrally provided on the camshaft 2 at a position corresponding to the other intake valve V2. Both cams C1 and C2 are formed in a shape that slightly shifts the opening and closing timings of both intake valves V1 and V2 in order to generate a swirl within a combustion chamber (not shown) of engine body 1, for example. Furthermore, a cam slipper 8 is integrally provided at the upper center of the first rocker arm 3, and is in sliding contact with the cam C1, and a cam slipper 9, which is in sliding contact with the cam C2, is integrally provided at the upper center of the second rocker arm 4.

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. This second rock shaft 12
A receiving portion 13 extending downward of the first rocker shaft 10 is integrally provided at the base of the first rocker shaft 10 .

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 includes 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 adjustment arm 11, so that the adjustment arm 11 is resiliently pushed by the plunger 17. It is 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 19 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 C1 in the direction in which the contact portion 24 contacts the intake valve V1, and the second rocker arm 4 rotates around the contact position between the cam slipper 8 and the cam C1. The contact portion 25 rotates about the contact position as a fulcrum in a direction to contact the intake valve V2.

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. Even though the other of the contact parts 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 that biases the valve in the direction of bringing it into contact with 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 draining oil from the hydraulic chamber 30, and also restricts the speed when air enters the hydraulic chamber 30. It also functions to exhaust the 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.

Next, the operation of this embodiment will be explained. According to the rotational operation of the camshaft 2, the first rocker arm 3 is driven to swing by the cam C1, and the second rocker arm 4 is driven to swing by the cam C2, and the intake valves V1 and V2 are driven to swing. The opening and closing operations are performed at timings according to the shapes of the cams C1 and C2.

Such first and second rocker arms 3, 4
The adjustment arm 11 that supports the swinging motion of is supported by an oil tappet 14 with upward elastic force, and the cam slipper 8 of the first rocker arm 3 abuts the cam C1 on the first rocker shaft 10.
The cam slipper 9 of the second rocker arm 4 is connected to the cam C2.
An upward elastic force is applied so that the rocker arms 3 and 4 come into sliding contact with each other, and accordingly, the contact portions 24 and 25 of each rocker arm 3 and 4 are urged to rotate in the direction of contacting the intake valves V1 and V2. There is. Furthermore, the abutting portion 25 of the second rocker arm 4 is provided with a plunger 26, and since this plunger 26 is biased by a spring in the direction of abutting the intake valve V2, the abutting portion 25
Before the plunger 26 contacts the intake valve V1, the plunger 26 contacts the intake valve V2, but when the plunger 26 contacts the intake valve V2, the plunger 26 retreats while compressing the spring 31, and its retreat speed is determined by the pressure from the hydraulic chamber 30. Since the oil draining speed is limited by the throttle 40, it becomes gentle, and therefore, the impact upon contact with the intake valve V2 is alleviated.

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. Furthermore, since the plunger 26 can move forward and backward, dimensional errors during initial assembly of the 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, and both rocker arms 3 and 4 can be moved forward and backward. It is possible to maintain a state in which the intake valves are always in contact with the intake valves V1 and V2 without any gap. Therefore, it is possible to achieve proper and quiet operation of the valve train.

FIG. 4 shows the main parts of another embodiment of the present invention, in which the throttle 40 of the hydraulic chamber 30 and the check valve 35 in the previously described embodiment are omitted, and instead, a check valve 35 is provided in the middle of the oil passage 32. A diaphragm 40' is provided.
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.

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. Further, the plunger 26 has contact portions 24 and 25.
It suffices if it is provided in at least one of the following.

C. Effects of the Invention As described above, according to the present invention, each cam follower is commonly pivotally supported by the first shaft, and the first shaft is pivotally supported by the second shaft fixed to the engine body. An oil tappet that is fixed to the adjustment arm and elastically supports the adjustment arm is attached to the engine body so as to urge each cam follower to rotate in the direction of contacting the intake valve or the exhaust valve using the point of contact with the camshaft as a fulcrum. Since each cam follower is provided in the valve, each cam follower can be brought into elastic contact with the intake valve or the exhaust valve at all times, and the load to be supported by the oil tappet can be freely selected by selecting the contact position of the oil tappet with the adjustment arm. There is also an advantage that it can be done.

[Brief explanation of drawings]

1 to 3 show one embodiment of the present invention, FIG. 1 is a plan view, and FIG. 2 is a -
3 is a cross-sectional view taken along the line -- in FIG. 1, and FIG. 4 is a vertical cross-sectional view of a main part of another embodiment of the present invention. 1... Engine body, 2... Camshaft, 3, 4
...first and second rocker arms as cam followers, 10...first rocker shaft as first shaft, 11...adjustment arm, 12...second rocker shaft as second shaft, 14...
...Oil tappet, 24, 25...Abutment part, 26
...Plunger, 30...Hydraulic chamber, C1, C2...
...Cam, V1, V2...Intake valve.

Claims (1)

[Scope of Claims] 1. A plurality of cam followers that can come into contact with the intake valve or exhaust valve to open the intake valve or exhaust valve that is biased in the valve closing direction, and a plurality of cam followers that can be brought into contact with the intake valve or the exhaust valve to open the intake valve or the exhaust valve that is biased in the valve closing direction, and an engine that drives the cam followers to swing. In a valve operating system for an internal combustion engine comprising a cam integrated with a camshaft that is rotationally driven in synchronization with rotation, each cam follower is commonly pivotally supported by a first shaft, and the first shaft is
It is fixed to an adjustment arm that is swingably supported by a second shaft that is fixed to the engine body, and the engine body has a cam follower that is attached to the engine body so that each cam follower is moved in the direction of contacting the intake valve or the exhaust valve using the contact point with the camshaft as a fulcrum. A valve operating device for an internal combustion engine, characterized in that an oil tappet is provided that elastically supports the adjustment arm to bias the adjustment arm. 2. At least one of the contact portions of the cam follower with the intake valve or the exhaust valve is provided with a spring in such a direction that one end faces a hydraulic chamber that limits oil drainage speed, and the other end contacts the intake valve or exhaust valve. 2. The valve operating system for an internal combustion engine according to claim 1, wherein the urged plunger is arranged to be movable forward and backward.