JPS63167007A - Valve system of internal combustion engine - Google Patents

Abstract

PURPOSE:To avoid high oil pressure from being exerted on a hydraulic tappet by providing an oil path for connecting between an oil pressure supply passage and the hydraulic tappet and providing a switching pin adapted to throttle the oil path as crossing the oil path and moving to the connection side. CONSTITUTION:During low-speed operation of an engine, switching pins 23-25 are in the state of disconnection, and circular grooves 40, 45 and circular recess portions 41, 46 are positioned corresponding to each other, so that low oil pressure from an oil pressure supply path 31 is not throttled, and supplied to each hydraulic tappet through respective oil paths 42, 43, 47, 48. On the other hand, during high-speed operation of the engine, high oil pressure is supplied to an oil pressure chamber 29, so that the respective switching pins 23-25 are moved against a return spring 26 and the first and second switching pins 23, 24 engage with the second and third guide grooves 33, 34, respectively to connect rocker arms 7-9 to one another. At this time, the first and third switching pins 23, 25 are moved to throttle between oil paths 42, 43 and between oil paths 47, 48.

Description

Detailed Description of the Invention A0 Object of the Invention (11 Industrial Field of Application) The present invention is directed to a plurality of cam followers including a cam follower provided with a hydraulic tappet that abuts an intake valve or an exhaust valve.
A connection switching mechanism that has switching pins that are arranged adjacent to each other so that they can operate in mutually different manners according to the rotation of the camshaft, and that move between a position where the cam follower is connected and a position where the cam follower is released by the action of hydraulic pressure. The present invention relates to a valve train for an internal combustion engine in which a hydraulic tappet and a connection switching mechanism are connected to the same hydraulic pressure supply path.

(2) Conventional technology Conventionally, such a valve train has been used, for example, in Japanese Patent Application Laid-Open No. 61-8151.
It is known from Publication No. 0.

(3) Problems to be Solved by the Invention In the above-mentioned conventional technology, hydraulic pressure is supplied to the hydraulic tappet and the connection switching mechanism from a common hydraulic pressure supply path. However, if a high hydraulic pressure is supplied to the hydraulic pressure supply path in order to connect the connection switching mechanism, it may affect the hydraulic tappet, and in some cases, the hydraulic tappet may operate abnormally, which is undesirable.

The present invention has been made in view of the above circumstances, and provides an internal combustion engine in which the hydraulic pressure supplied to the hydraulic tappet is kept at a relatively low pressure when the hydraulic pressure in the hydraulic pressure supply path is set to a high pressure in order to cause the coupling switching mechanism to operate in a coupled manner. The purpose of this invention is to provide a valve train.

B1 Structure of the Invention (Means for Solving 11 Problems) According to the present invention, a cam follower provided with a hydraulic tappet is provided with a hydraulic pressure supply path and an oil path connecting between the hydraulic tappets, and the switching bin of the connection switching mechanism is , is disposed on the cam follower across the cedar oil passage, and is configured to narrow the oil passage as the cam follower moves from the disconnected position to the connected position.

(2) Effect According to the above configuration, when the hydraulic pressure in the hydraulic pressure supply path is set to high pressure and the switching pin of the connection switching mechanism is moved to the connected position side, the oil path to the hydraulic tappet is constricted, so that high hydraulic pressure is applied to the hydraulic tappet. It is possible to avoid this.

(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 1a and lb provided in the engine body E are connected to the engine from the crankshaft of the engine. A protrusion 3, a low-speed cam 4, a high-speed cam 5, and a cam follower pivotally supported on a rocker shaft 6 parallel to the camshaft 2, which are integrally provided on a camshaft 2 that is rotationally driven at a reduction ratio of 1/2. 1st, 2nd and 30th as
The rocker arms 7, 8, 9 and the connection switching mechanism 10 provided between each rocker arm full 9 are operated to open and close.

The camshaft 2 is rotatably disposed above the engine body E, the low-speed cam 4 is integrated with the camshaft 2 at a position corresponding to one intake valve 1a, and the protrusion 3 is connected to the other intake valve 1a. It is integrated into the camshaft 2 at a position corresponding to the valve 1b, and the high-speed cam 5 is integrated into the camshaft 2 between the raised portion 3 and the low-speed cam 4. The raised part 3 is formed in a perfect circle concentric with the camshaft 2, and the low-speed cam 4 has a high part 4a with a relatively small amount of protrusion along the radial direction of the camshaft 2, and a base inner part 4b. have The high-speed cam 5 has a radially outward protrusion of the camshaft 2 that is larger than the high portion 4a, and a high portion 5a that extends over a wider center angle range than the high portion 4a, and a base interior 5b. has.

The rocker shaft 6 is fixedly arranged below the camshaft 2. The rocker shaft 6 includes a tenth lug arm 7 that is interlocked and connected to one intake valve 1a, and a twentieth lug arm 8 that is interlocked and connected to the other intake valve 1b.
The third arm located between the first and 20th arm 7.8
The two arms 9 are pivoted adjacent to each other. Further, a cam slipper 11 that slides on the low-speed cam 4 is provided on the upper part of the 10th claw arm 7, a sliding contact part 12 that slides on the raised part 3 is provided on the upper part of the 20th claw arm 8, and A cam slipper 13 is provided at the upper portion to slide into contact with the high-speed cam 5.

On the other hand, flanges 14.15 are provided at the top of both intake valves 1a and lb, and these flanges 14.15 and the engine body E
Valve springs 16, 17 are interposed between each intake valve 1a.
, lb are biased in the valve closing direction, that is, upward. Further, the tips of the first and 20th lever arms 7.8 are provided with hydraulic tappets TL and T2 each having a discharge hole 18 at the upper end.
are provided, and the first and 20th/7th arm 7.
8 connects the intake valves 1a and 1b via hydraulic tappets TI and T2.
comes into contact with.

Referring also to FIG. 3, the 30th hook arm 9 slightly extends from the rocker shaft 6 toward both intake valves 1a and lb, and this 30th hook arm 9 is located between the engine body E and the 30th hook arm 9. The provided resilient biasing means 19 resiliently biases the cam 5 in the direction of sliding contact with the high-speed cam 5.

The spring biasing means 19 includes a bottomed cylindrical glue lid 20 whose closed end is in contact with the 30th hook arm 9, and a lifter spring 21 interposed between the lifter 20 and the engine body E. is slid into a bottomed hole 22 bored on the side of the engine body.

In FIG. 4, a connection switching mechanism 10 is provided between each of the rocker arms 7 to 9 for switching between connection and disconnection.

The connection switching mechanism 10 includes second and 30th hook arms 8,
a first switching bin 23 that can connect between the third and first switching bins;
A second switching pin 24 that can connect the two switching pins 8.7, a third switching pin 25 that restricts the movement of the first and second switching bins 23.24, and each connecting pin 23 to 25 on the connection release side. and a biasing return spring 26.

A first guide hole 27 parallel to the rocker shaft 6 is bored in the 20th hook arm 8.
The end opposite to the 30th hook arm 9 of 7 is the closing member 2
Blocked at 8. The first guide hole 27 has a first switching bin 2.
3 are slid together, and the closing member 2 is inserted into the first guide hole 27.
A hydraulic chamber 29 is defined between the switching bin 8 and the first switching bin 23 . Further, a communication passage 30 communicating with the hydraulic chamber 29 is bored in the 20th lever arm 8, and a hydraulic pressure supply passage 31 communicating with a hydraulic pressure supply source (not shown) is provided in the rocker shaft 6. The communication path 30 and the hydraulic pressure supply path 31 are always in communication with each other through a communication hole 32 formed in the side wall of the rocker shaft 6 regardless of the swinging state of the 20th lever arm 8.

In the 30th hook arm 9, a second guide hole 33 having the same diameter as the first guide hole 27 is bored parallel to the rocker shaft 6 between both sides thereof. A second switching pin 24 having a length spanning the entire length is slid together.

A third guide hole 34 having the same diameter as the second guide hole 33 is bored in the tenth claw arm 7 in parallel with the rocker shaft 6, and the third guide hole 34 is opposite to the third guide hole 34 in the 30th claw arm 9. The side end is closed with a closing member 35.

A third switching bin 25 is slidably fitted into the third guide hole 34, and a shaft portion 36 coaxially connected to the third switching bin 25 is inserted into the third switching bin 25.
is movably inserted into a guide hole 37 formed in the closing member 35. Furthermore, a return spring 26 is interposed between the closing member 35 and the third switching bin 25 so as to surround the shaft portion 36 . The switching pins 23 to 2 are brought into contact with each other by this return spring 26.
5 is urged toward the disconnection side, that is, toward the hydraulic chamber 29 side.

In a state where high oil pressure is not supplied to the hydraulic chamber 29, each of the switching bins 23 to 25 is moved toward the connection release side by the spring force of the return spring 26, and in this state, the first and second switching bins 23, 24 are The contact surfaces are the second and 30th hook arms 8
．． The abutting surfaces of the second and third switching pins 24.25 are located at positions corresponding to between the third and tenth lever arms 9.
7, and the rocker arms 7 to 9 are not connected. Furthermore, when high hydraulic pressure is supplied to the hydraulic chamber 29, each of the switching pins 23 to 25 moves in a direction away from the hydraulic chamber 29 against the spring force of the return spring 26, and the first switching pin 23 moves into the second guide hole 33. The second switching pin 24 slides into the third guide hole 34, and the rocker arms 7 to 9 are connected.

An annular groove 40 is provided on the outer peripheral surface of the third switching bin 25,
When the third switching pin 25 is in the disconnection position, the annular groove 4
An annular recess 41 is provided on the inner peripheral surface of the third guide hole 34 at a position corresponding to 0. The width of the annular groove 40 and the annular recess 41 along the axis of the third switching bin 25 is the same as that of the third switching bin 25.
5 is set to be shifted from the uncoupled position to the coupled position. Also the 10th
The hook arm 7 is provided with an oil passage 42 having one end communicating with the hydraulic tappet TI and the other end communicating with the annular recess 41, and an oil passage 43 with one end communicating with the annular recess 41. The other end of this oil passage 43 is always in communication with the hydraulic pressure supply passage 31 via a communication hole 44 formed in the side wall of the rocker shaft 6. Therefore, the space between the oil passages 42 and 43 is narrowed when the third switching bin 25 moves to the connection position side.

An annular groove 45 is provided on the outer peripheral surface of the first switching pin 23,
When the first switching pin 23 is in the disconnection position, the annular groove 4
An annular recess 46 is provided on the inner circumferential surface of the first guide hole 27 at a position corresponding to 5 . The widths of the annular groove 45 and the annular recess 46 along the axial direction of the first switching pin 23 are set so that the positions of the first switching pin 23 are shifted from each other when the first switching pin 23 moves from the disconnected position to the connected position. . Also the second
The hook arm 8 has an oil passage 47 having one end communicating with the hydraulic tappet T2 and the other end communicating with the annular recess 46.
is bored, and an oil passage 48 whose one end communicates with the annular recess 46 and the other end communicates with the communication passage 30 is bored. Therefore, the space between the oil passages 47 and 48 is constricted when the first switching pin 23 moves toward the connection position.

Next, the operation of this embodiment will be explained. When the engine is operated at low speed, relatively low pressure hydraulic pressure is supplied to the hydraulic chamber 29, and each switching bin 23 to 25 is moved toward the hydraulic chamber 29 side by the spring force of the return spring 26. is in the uncoupled position with maximum movement. In this state, the first and second switching pins 23, 24
The abutment surfaces of the switch pins 24.25 are located at positions corresponding to between the second and 30th hook arms 8.9, and the abutment surfaces of the second and third switching bins 24.25 are located between the third and tenth hook arms 9.7. in position. Therefore, each of the rocker arms 7 to 9 is in a state where relative angular displacement is possible with respect to each other.

In this disconnected state, the 10th claw arm 7 swings in sliding contact with the low-speed cam 4 due to the rotational movement of the camshaft 2, and the 20th claw arm 8 comes to rest in sliding contact with the raised portion 3. It remains as it is.

Therefore, one intake valve 1a opens and closes at a timing and lift amount depending on the shape of the low-speed cam 4, and the other intake valve 1b remains closed.

At this time, the 30th hook arm 9 swings in response to sliding contact with the high-speed cam 5, but the swinging action has no effect on the first and 20th hook arms 7.8.

In addition, in this disconnected state, the annular groove 40 and the annular recess 41 and the annular groove 45 and the annular recess 46 are in corresponding positions, and the relatively low pressure hydraulic pressure from the hydraulic pressure supply path 31 is throttled. Without oil passage 42, 43; 4
7.48 and is supplied to the hydraulic tappets Tl and T2.

During high-speed operation of the engine, relatively high-pressure hydraulic pressure is supplied to the hydraulic chamber 29. As a result, each of the switching bins 23 to 25 moves toward the connection position against the spring force of the return spring 26, as shown in FIG.
The second switching pin 24 slides into the third guide hole 34, and the rocker arms 7 to 9 are connected. At this time, since the amount of swing of the 30th hook arm 9 in sliding contact with the high speed cam 5 is the largest, the first and 20th hook arms 7.8
0 swings with the arm 9, and both intake valves la and lb have timing and riff +- according to the shape of the high-speed cam 5.
It opens and closes with IT.

During the connection operation of the connection switching mechanism IO, the oil passage 42
, 43 and between the oil passages 47, 48 are narrowed by the movement of the first and third switching pins 23, 25. On the other hand, in the hydraulic tappet TI T2, since oil is discharged from the discharge hole 18, the high oil pressure from the hydraulic pressure supply path 31 does not directly act due to the balance between the amount of discharged oil and the throttled oil supply amount. The relatively low pressure is applied to the hydraulic tappet Tl,
Acts on T2. Therefore, hydraulic tappet T1. It is possible to prevent abnormal operation from occurring at T2 due to the action of high oil pressure.

Although the above embodiments have been described in connection with an intake valve, it is also possible to implement the present invention in connection with an exhaust valve.

C6 Effects of the invention As described above, according to the present invention, the cam follower provided with a hydraulic tappet is provided with a hydraulic pressure supply path and an oil path connecting between the hydraulic tappets, and the switching bottle of the connection switching mechanism crosses the core oil path. The oil passage is arranged in the cam follower, and the oil passage is narrowed in response to the movement from the uncoupling position to the coupling position. When the coupling operation is performed, the hydraulic pressure to the hydraulic tappet is throttled by the switching bin, and it is possible to avoid high hydraulic pressure from acting on the hydraulic tappet, thereby preventing abnormal operation of the hydraulic tappet.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a vertical side view, and is a sectional view taken along the line I--T in FIG. 2, FIG. 2 is a plan view of FIG. 1, and FIG. Sectional view along the mm line in Figure 2, No. 4
The figure is Fig. 1 when the connection switching mechanism is in the disconnected state.
t/-IV line sectional view, FIG. 5 is a sectional view corresponding to FIG. 4 when the connection switching mechanism is in the connected state. la, lb...Intake valve, 2...Camshaft, 7゜8.9...Rocker arm as cam follower, IO
...Connection switching mechanism, 23,24.25...Switching bin, 31...Hydraulic pressure supply path, 42,43,47.48...
・Oil path・ Tl, T2...Hydraulic tabet Fig. 4 Fig. 5

Claims (1)

[Claims] A plurality of cam followers, including a cam follower equipped with a hydraulic tappet that contacts the intake valve or exhaust valve, are arranged adjacent to each other so that they can operate in different manners according to the rotation of the camshaft, and the cam followers are connected by the action of hydraulic pressure. A connection switching mechanism having a switching pin that moves between a position and a decoupling position is provided between the cam followers;
In a valve train for an internal combustion engine in which the same hydraulic supply path is connected to the hydraulic tappet and the connection switching mechanism, the cam follower equipped with the hydraulic tappet is provided with a hydraulic pressure supply path and an oil path connecting the hydraulic tappets, and the connection switching mechanism is An internal combustion engine characterized in that a switching pin of the mechanism is disposed on a cam follower across the oil passage and is configured to narrow the oil passage in response to movement of the switching pin from a disconnected position to a connected position. valve train.