JPH0278717A - Valve gear of internal combustion engine - Google Patents

Abstract

PURPOSE:To enable the opening and closing behavior of valves to be more precisely controlled for improving the output of an engine by uniting a cam shaft with cams respectively slidably contacting drive and free rocker arms and shaped differently, while providing a connecting means for changing over the condition of interconnecting the respective rocker arms and the condition of allowing said arms to be relatively displace. CONSTITUTION:Intake valves 1a, 1b as a pair of engine valves are opened and closed by low and high speed cams 3, 5 provided on a cam shaft 2, first and second drive rocker arms 7, 8 pivotably supported by a rocker shaft 6 parallel to the cam shaft 2 and a free rocker arm 9. Then, a low speed cam 3 and high speed cam 5 are shaped to correspond respectively to the low and high speed running of the engine. A connecting means 21 is provided which makes the respective rocker arms 7-9 slidably cintact each other while changing over the condition of enabling these arms to be angularly displaced relative to each other and the condition of interconnecting integrally these arms.

Description

Detailed Description of the Invention Δ0Object of the Invention (1) Industrial Application Field The present invention relates to a cam that is integrated into a camshaft that is rotationally driven in synchronization with the rotation of an engine, and The present invention relates to a valve operating system for an internal combustion engine that includes a rocker arm for opening and closing an engine valve accordingly.

(2) Conventional technology In such a valve train, if the operating mode of the engine valve can be changed according to the operating state of the engine, it is possible to improve engine output, reduce fuel consumption, and improve idle characteristics, etc. Japanese Unexamined Patent Publication No. 59-37223 discloses a system in which the operating mode of some of a plurality of engine valves is changed depending on the operating state of the engine.

(3) Problems to be Solved by the Invention By the way, in the above conventional system, a rocker arm that is interlocked and connected to the engine valve and a rocker arm that slides on the cam are arranged adjacent to each other, and when these rocker arms are connected, The cam opens and closes the engine valve, and when the connection is released, the engine valve stops operating. However, the remaining engine valves are opened and closed in a fixed manner regardless of the operating state of the engine. If it were possible to open and close the engine valves in a manner compatible with low-speed engine operation during operating conditions, and to open and close the engine valves in a manner compatible with high-speed engine operation during high-speed engine operation, it would be possible to further improve engine output. In addition, when one intake valve or one exhaust valve is provided per cylinder, it is not possible to stop the operating body even during low-speed operation, and even in such a case, it is necessary to adapt the engine valve to a mode that corresponds to low-speed operation. If the engine can be opened and closed in a manner that corresponds to high-speed operation, it is possible to improve the engine output.

The present invention has been made in view of the above circumstances, and provides a valve operating system for an internal combustion engine that aims to improve engine output by constantly opening and closing the engine valve while changing its operating mode according to the operating state of the engine. The purpose is to provide

B1 Structure of the Invention (1) Means for Solving the Problems According to the present invention, the drive rocker arm that is interlocked and connected to the engine valve and the free rocker arm that can be free with respect to the engine valve are movable relative to each other and are adjacent to each other. The camshaft has different cams that slide into sliding contact with the drive rocker arm and the free rocker arm, respectively, and are integrated with the cams. Connecting means is provided that allows switching between a state that allows relative displacement of the state.

(2) Effect According to the above configuration, the operating mode of the drive rocker arm changes according to the switching operation of the coupling means to connect and disconnect from the adjacent free rocker arm, and therefore the engine valve connected to the drive rocker arm changes. The opening/closing operation mode is changed according to the operating condition of the engine, and the opening/closing operation is constantly performed.

(3) Embodiment Hereinafter, an embodiment of the present invention will be explained with reference to the drawings. First, in FIGS. 1 and 2, the intake valves 1a and 1b as a pair of engine valves provided in the engine body E are A low-speed cam 3 and a high-speed cam 5 are integrally installed on a camshaft 2 that is driven at a rotation ratio A in synchronization with the rotation of 1st. Second drive rocker arm? , 8 and the free rocker arm 9 to open and close.

Further, the engine body E is provided with exhaust valves (not shown) as a pair of engine valves, and these exhaust valves are also opened and closed in the same manner as the intake valves 1a and lb described above.

The camshaft 2 is rotatably disposed above the engine body E, and the low-speed cam 3 is integrally provided on the camshaft 2 at a position corresponding to one intake valve 1a. Also, the high speed cam 5 has both intake valves 1a.

It is integrally provided on the camshaft 2 at a position corresponding to between lbs. Moreover, the low-speed cam 3 has a shape suitable for low-speed operation of the engine, and has a high portion 3a that protrudes outward in a relatively small amount along the radial direction of the camshaft 20. Further, the high-speed cam 5 has a shape suitable for high-speed operation of the engine, and the amount of radially outward protrusion of the camshaft 2 is larger than the high-position portion 3a of the low-speed cam 3 and is higher than the high-position R3a. It also has a high portion 5a over a wide center angle range. Furthermore, a perfectly circular raised portion 4 is integrally provided on the camshaft 2 at a position corresponding to the other intake valve 1b, and this raised portion 4 closes the intake valve 1b during low-speed operation. It works to maintain.

The rocker shaft 6 is fixedly arranged below the camshaft 2. A first drive rocker arm 7, a second drive rocker arm 8 and a free rocker arm 9 are respectively pivotally supported on this rocker shaft 6, and the first and second drive rocker arms 7.8 are formed basically in the same shape. That is, the first and second drive rocker arms 7.8 have their bases pivotably supported on the rocker shaft 6 at positions corresponding to the intake valves 1a, lb, respectively.

It extends to a position above 1b. Further, a cam slipper 10 that slides on the low-speed cam 3 is provided on the top of the first drive rocker arm 7, and a contact portion 11 that can come into contact with the raised portion 4 is provided on the top of the second N-movement rocker arm 8. In the first and second drive rocker arms 7.8, each intake valve 1a
, lb, each intake valve 1a, lb
A tappet screw 12.13 that can abut on the upper end of the housing is screwed so as to be movable forward and backward.

On the other hand, flange portions 14 and 15 are provided at the upper portions of both intake valves 1a and Lb. These flanges 14.15 and engine body E
and a valve spring 16.1 surrounding the intake valves 1a and lb.
7 is interposed, and each intake valve 1a, lb is biased toward the valve closing direction, that is, upward, by a valve spring 16, 17.

Referring also to FIG. 3, the free rocker arm 9 has a first
and a second drive rocker arm 7.8 on the rocker shaft 6. This free rocker arm 9 extends from the rocker shaft 6 to both intake valves 1a.

It extends slightly to the lb side, and a high-speed cam 5 is mounted on the top of it.
A cam slipper 18 is provided which slides into contact with the cam slipper 18.

Furthermore, a bottomed cylindrical glue lid 19 is in contact with the lower surface of the end of the free rocker arm 9, and this lifter 19 is interposed between the engine body E and is urged upward by a lid spring 20. Ru. As a result, the cam slipper 18 of the free rocker arm 9 is always in sliding contact with the high-speed cam 5.

In FIG. 4, the first drive rocker arm 7, the second drive rocker arm 8, and the free rocker arm 9 are in sliding contact with each other, allowing relative angular displacement, and allowing each rocker arm 7 to 9 to be integrated. The connecting means 21 that can switch between the connecting state and the connecting state is connected to each rocker arm. , 8. 9.

The coupling means 21 has a first piston 22 which is movable between a position where the first drive rocker arm 7 and the free rocker arm 9 are coupled and a position where the coupling is released, and a position where the free rocker arm 9 and the second drive rocker arm 8 are coupled and A second piston 23 that is movable between positions where the connection is released, a stopper 24 that restricts movement of the first and second pistons 22.23, and a stopper 24 that moves the first and second pistons 22.23 to the connection release position side. The stopper 24 is provided with a spring 25 that urges the stopper 24 to move.

The first driving rocker arm 7 has a first guide hole 26 with a bottom that opens toward the free rocker arm 9 and is parallel to the rocker shaft 6. The first guide hole 26 has a closed end. A small diameter portion 28 is provided via a stepped portion 27 . The first piston 22 is slidably fitted into the first guide hole 26 , so that the first piston 22 and the first guide hole 2
A hydraulic chamber 29 is defined between the closed end of 6 and the closed end of 6. Also the first
The drive rocker arm 7 has an oil passage 30 communicating with the hydraulic chamber 29.
is bored in the rocker shaft 6, and an oil passage 31 communicating with a hydraulic pressure supply source (not shown) is bored in the rocker shaft 6. In addition, both oil lines 3
0.31 is always communicated through a communication hole 32 formed in the side wall of the rocker shaft 6, regardless of the swinging state of the first drive rocker arm 7.

The axial length of the first piston 22 is such that one end thereof has a stepped portion 27.
when the other end is in contact with the first drive rocker arm 7.
It is set so that it does not protrude toward the free rocker arm 9 side from the side surface facing the free rocker arm 9 side. Further, a spring 33 having a smaller spring force than the spring 25 is interposed between the closed end of the first guide hole 26 and the first piston 22.

A guide hole 34 corresponding to the first guide hole 26 of the first drive rocker arm 7 is bored in the free rocker arm 9 between both sides, and the guide hole 34 has a length corresponding to the entire length of the guide hole 34. The second piston 23 has a
are rubbed together. Moreover, the outer diameter of this second piston 23 is
It is set to be the same as the first piston 22.

The second driving rocker arm 8 is provided with a bottomed second guide hole 35 that is open toward the free rocker arm 9 side and corresponds to the guide hole 34 . The stopper 24 is slid together. A small diameter aB37 is provided on the closed end side of the second guide hole 35 via a regulating step 36. Further, the second drive rocker arm 8 has an insertion hole 38 that passes through the closed end of the second guide hole 35.
It is drilled concentrically with stopper 5 and has a small diameter.
A small-diameter guide rod 39 provided integrally and concentrically with 4 is inserted into the insertion hole 38. Further, a coiled spring 25 surrounding the guide rod 39 is interposed between the stopper 24 and the closed end of the second guide hole 35 .

Next, the operation of this embodiment will be explained. When the engine is operated at low speed, no hydraulic pressure is supplied to the hydraulic chamber 29 of the coupling means 21, and the stopper 24 is pressed toward the free rocker arm 9 by the spring 25, so that the first piston 22 has moved via the second piston 23 until it abuts against the stepped portion 27. In this state, the contact surfaces of the first and second pistons 22 and 23 are connected to the first drive rocker arm? and a position corresponding to the sliding surface of the free rocker arm 9, and the second piston 2
3 and the contact surface of the stopper 24 are free rocker arms 9$
and at a position corresponding to the sliding surface of the second drive rocker arm 8. Therefore, each rocker arm? , 8. 9 are in sliding contact with each other, and the first and second pistons 2
2.23 and second piston 23 and stopper 24
By slidingly contacting each other, relative angular displacement is possible.

When the coupling means 21 is in the disconnected state, the rotation of the camshaft 2 causes the first drive rocker arm 7 to
swings in response to sliding contact with the low-speed cam 3, and one intake valve 1a is opened and closed by retarding its opening timing and advancing its closing timing, or by reducing the amount of lift. Ru. On the other hand, the second drive rocker arm 8 does not swing because the raised portion 4 is perfectly circular, and the other intake valve 1b remains closed. At this time, the free rocker arm 9 swings due to sliding contact with the high-speed cam 5, but the swinging movement is caused by both intake valves 1a,
It has no effect on the operation of 1b.

In this way, when the engine is operating at low speed, only one intake valve 1a is opened or closed, thereby reducing fuel consumption and improving idling characteristics.

During high-speed operation of the engine, the hydraulic chamber 29 of the coupling means 21
Hydraulic pressure is supplied to the As a result, as shown in FIG. 5, the first piston 22 moves toward the free rocker arm 9 against the spring force of the spring 25, and the second piston 23 moves toward the first
It is pushed by the piston 22 and moves to the second drive rocker arm 8 side. As a result, the first and second pistons 22.23 move until the stopper 24 comes into contact with the restriction step 36, the first piston 22 connects the first drive rocker arm 7 and the free rocker arm 9, and the second piston 23 The free rocker arm 9 and the second driving rocker arm 8
are concatenated.

In this way, each rocker arm? , 8. 9 are connected to each other by the connecting means 21, the amount of swing of the free rocker arm 9 in sliding contact with the high-speed cam 5 is the largest, so the first and second drive rocker arms 7.8 swing together with the free rocker arm 9. do. Therefore, both intake valves 1a and 1b are opened and closed with their opening timings advanced, their closing timings delayed, and their lift amounts increased.

The intake valve 1a, which is interlocked and connected to the first drive rocker arm 7 in this way, is always opened and closed when the engine is operating, and changes its opening and closing operation mode according to the switching operation of the connecting means 21, thereby changing the engine operating state. The engine output can be further improved by enabling precise opening/closing operation modes according to the engine speed.

The effect of improving the output of the engine due to the function of the connecting means 21 as described above is illustrated by curve A in FIG. 6. On the other hand, curve B shows a conventional internal combustion engine in which the engine valve does not stop operating when the engine is running at low speed; Conventional one (Japanese Unexamined Patent Publication No. 59-37223
It is clear that the configuration of this embodiment improves the output over a wide range from low speed ranges to high speed ranges.

In the above description, the portions related to the intake valves 1a and 1b have been described, but the pair of exhaust valves are also operated in the same manner as the intake valves.

C1 Effects of the Invention As described above, according to the present invention, the drive rocker arm that is interlocked and connected to the engine valve and the free rocker arm that can be free with respect to the engine valve are arranged adjacently so as to be movable relative to each other, and the camshaft The drive rocker arm and the free rocker arm have cams that slide in sliding contact with each other and are integrated with different shapes, and each rocker arm has two states: one in which the rocker arms are integrally connected, and the other in which the relative displacement of each rocker arm is allowed. Since the engine valve connected to the drive rocker arm is always open/closed, the opening/closing mode can be changed according to the engine operating state, allowing for more precise control of the opening/closing mode. This makes it possible to improve engine output.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a plan view, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line ■-■ in FIG. Figure 4 is a sectional view taken along the rV-rV line in Figure 2, Figure 5 is a sectional view corresponding to Figure 4 during high-speed operation, and Figure 6 is a sectional view corresponding to Figure 4 during high-speed operation.
The figure shows the output characteristics of the engine.

Claims (1)

[Claims] In a valve train for an internal combustion engine, the engine includes a cam integrated with a camshaft that is rotationally driven in synchronization with the rotation of the engine, and a rocker arm that opens and closes the engine valve in accordance with the rotational movement of the cam. A drive rocker arm that is interlocked and connected to the valve and a free rocker arm that can be free with respect to the engine valve are arranged adjacently so as to be able to move relative to each other, and the camshaft has a cam that slides in sliding contact with the drive rocker arm and the free rocker arm, respectively. The rocker arms are integrated with different shapes, and each rocker arm is provided with a connecting means that enables switching between a state in which the rocker arms are integrally connected and a state in which relative displacement of each rocker arm is allowed. Valve gear for internal combustion engines.