JPH0351886B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a valve operation control device for an internal combustion engine.

(Technical Background of the Invention) Generally, some high-output internal combustion engines are of a type in which one cylinder is provided with two intake or exhaust valves having the same function. This type of internal combustion engine has a large communication passage between the intake passage or exhaust passage and the combustion chamber, which is opened and closed by two valves, so it can take in a large amount of air-fuel mixture or exhaust a large amount of exhaust gas. , suitable for operating internal combustion engines at high revolutions and high output.

However, when this type of internal combustion engine is operated at low rotation speeds, the amount of intake air decreases, and this small amount of air is sucked into the combustion chamber through a wide communication path, which further reduces charging efficiency. Furthermore, since intake air blow-through generally occurs in the low rotational speed range, if the exhaust valve opening area is large, the filling efficiency decreases, and as a result, the output of the internal combustion engine decreases.

In order to eliminate this problem, when the internal combustion engine is operating at low speeds, only one of the two valves is opened and closed, and the other valve is stopped from opening and closing, thereby reducing the communication path between the intake or exhaust passage and the combustion chamber. Generally, methods are used to narrow the area of the engine so that intake inertia can be used even during low-speed operation, or to reduce intake air blow-through.

(Prior Art and its Problems) A valve train for carrying out this method is known from Japanese Patent Application Laid-Open No. 188716/1983.

In such a conventional device, a camshaft with a low-speed cam and a camshaft with a high-speed cam are supported in one holder, and a single rocker arm has a low-speed slipper that slides on the low-speed cam and a camshaft with a high-speed cam. A high-speed slipper that comes into sliding contact is provided, and when the internal combustion engine rotates at low speed, the holder is swung upward to bring only the low-speed camshaft into sliding contact with the rocker arm, and when the internal combustion engine is rotated at high speed, the holder is swung downward to allow the holder to be swung downwards. It is constructed so that only the camshaft is in sliding contact with the rocker arm.

Therefore, since the holder is configured to swing up and down together with the rocker arm, the structure is complicated, and rapid switching is not possible, making it unsuitable for high-speed internal combustion engines. Further, since a vertically swingable holder for supporting the rocker arm and a box for accommodating the holder are required, there is a problem that the circumference of the cylinder head becomes large.

(Object of the invention) The present invention has been made in view of the above circumstances, and is capable of obtaining high output over the entire rotation range of an internal combustion engine from low speed to high speed, while having a simple and compact structure. An object of the present invention is to provide a valve operation control device for an internal combustion engine.

(Means for solving the problem) In order to solve the above problem, in the present invention,
A camshaft that has a plurality of cams with different profiles for the intake valve or exhaust valve provided for each cylinder and is rotationally driven in synchronization with the rotation of the engine, and one cam among the plurality of cams. and a first valve driving member that comes into contact with both the intake valve or the exhaust valve and directly drives the intake valve or the exhaust valve to open or close in response to the rotational movement of the one cam, and another of the plurality of cams. a second valve driving member that comes into contact with the cam, and the first and second valve driving members are selectively switched between a state in which they are integrally connected and a state in which they can be relatively displaced. A switching means was provided.

(Function) If the valve driving member (first valve driving member) and the auxiliary valve driving member (second valve driving member) are integrally connected by the connection switching means, the connection between one cam and the other cam can be changed. By making each profile different from each other, a transmission path from another cam → auxiliary valve drive member → connection switching means → valve drive member → intake and exhaust valve is formed, and the operation control of the intake and exhaust valves during high-speed rotation of the internal combustion engine is formed. On the other hand, the connection switching means can be applied to the first and second
If the valve drive member of 1 is set to a non-interlocking state, cam 1→
A transmission path from the valve drive member (valve drive member 1) to the intake and exhaust valves is formed, and can be applied to control the operation of the intake and exhaust valves at low rotation speeds of the internal combustion engine.

In any case, the valve driving member driven by the rotational movement of the cam can directly control the opening and closing of the intake and exhaust valves.

(Example) An example of the present invention will be described below based on the drawings. FIG. 1 is a partially omitted longitudinal cross-sectional view of a 4-cylinder, 16-valve internal combustion engine. In this figure, internal combustion engine 1
A piston 4 is slidably fitted into a cylinder barrel 3 within the cylinder block 2. The cylinder head 5 mounted on the upper part of the cylinder block 2 is provided with an intake passage 7 and an exhaust passage 8 communicating with a combustion chamber 6, and a carburetor (not shown) is provided in the intake passage 7.
However, exhaust pipes (not shown) are connected to the exhaust passages 8, respectively. The communication part (intake port) between the intake passage 7 and the combustion chamber 6 is formed by two intake valves 9 arranged in parallel with each other.
The communication section (exhaust port) between the exhaust passage 8 and the combustion chamber 6 is also opened and closed by two exhaust valves 10 (only one shown) arranged in parallel with each other.

These two intake valves 9 and exhaust valves 10 are opened and closed by valve operation control devices 11 and 12, respectively. The valve operation control device 11 for the intake valve 9 and the valve operation control device 12 for the exhaust valve 10 have the same configuration. Regarding the valve actuation control device 12, the same parts in the drawings are denoted by the same reference numerals, and the explanation thereof will be omitted.

The two intake valves 9 ₁ and 9 ₂ are fitted in a guide cylinder 13 and biased by a spring 14 in a direction to close the communication portion between the intake passage 7 and the combustion chamber 6 . At the upper ends of the two intake valves ₉₁ and ₉₂ , there is a main rocker arm (first
The respective ends 15a and 15b of the valve driving member) 15 are in abutting engagement with each other. The main rocker arm 15 is adjacent to a sub rocker arm (second valve driving member) 16, and its boss portions 15c, 16c are rotatably fitted onto a common rocker arm shaft 17. These main and sub rocker arms 15 and 16 have slippers 18 and 19, and the slipper 18 of the main rocker arm 15 has a low speed cam 21 integrated with a camshaft 20.
In addition, the slipper 19 of the sub-rocker arm 16 is in sliding contact with a high-speed cam 22 which is provided integrally with the camshaft 20 adjacent to the low-speed cam 21. FIG. 4 is a cam profile curve diagram of the low-speed cam 21 and the high-speed cam 22, and as is clear from the figure, the lift curve of the high-speed cam 22 is always higher than or approximately the same as the lift curve of the low-speed cam 21. It is set so that Note that the auxiliary rocker arm 16 is not engaged with the intake valves 9 ₁ and 9 ₂ , and only the main rocker arm 15 is engaged with the intake valves 9 ₁ and 9 ₂ . Further, the auxiliary rocker arm 16 is urged toward the high-speed cam 22 by a torsion spring 31.

The main rocker arm 15 and the secondary rocker arm 16
The connection switching means 23 selectively switches between an integrally connected state, that is, an interlocked state, and a relatively movable state, that is, a non-interlocked state. The connection switching means 23 has a first pin (plunger) 24 having a piston function. The first pin 24 is fitted into a fitting hole (cylinder) 25 of the main rocker arm 15 so as to be slidable through a predetermined stroke. A hydraulic chamber 25a defined between the inner end surface of the first pin 24 and the inner end surface of the main rocker arm 15 includes an oil passage 26 inside the main rocker arm 15 and an oil passage hole 17 of the rocker arm shaft 17.
a and an oil passage 17b to a hydraulic pressure supply source (not shown), and when the internal combustion engine rotates at high speed,
Hydraulic pressure is automatically supplied to the hydraulic chamber 25a, and the hydraulic pressure within the hydraulic chamber 25a is automatically released during low speed rotation. The first pin 24 is connected to the hydraulic chamber 2
The spring 27 provided on the auxiliary rocker arm 1
6 side is biased. The outer end surface of the first pin 24 is connected to the fitting hole (cylinder) 2 of the sub rocker arm 16.
It abuts on one end surface of a second pin 29 that is fitted within the pin 8 so as to be slidable over a predetermined stroke. The second pin 29 is biased toward the main rocker arm 15 by a spring 30. The biasing force of the spring 27 that biases the first pin 24 toward the auxiliary rocker arm 16 is set to be smaller than the biasing force of the spring 30 that biases the second pin 29 toward the main rocker arm 15. There is.

Therefore, when hydraulic pressure is not supplied to the pressure chamber 25a, the contact surface between the first pin 24 and the second pin 29 is located at the boundary between the two rocker arms 15 and 16, and the two rocker arms 15 , 16 are in a non-linked state.

Next, the valve operation control device 1 of the present invention having the above configuration
The effect of No. 1 will be explained. During high-speed rotation of the internal combustion engine 1, hydraulic pressure is supplied into the hydraulic chamber 25a through the oil passage 17b, the oil passage 17a, and the oil passage 26, and the hydraulic pressure causes the first pin 24 and the second pin 29 to spring 30. The first pin 24 slides in one direction against the urging force of the first pin 24.
Both rocker arms 15 and 16 are interlocked with each other via the locker arms 15 and 16. As mentioned above, since the lift curve of the high-speed cam 22 is always higher than or substantially the same as the lift curve of the low-speed cam 21, the rotation of the high-speed cam 22 causes the slipper 19 to be integrated with the sub rocker arm 16 in sliding contact with the cam 22. The main rotsuka arm 15
The intake valves 9 ₁ and 9 ₂ open and close according to the high-speed cam 22, and although the low-speed cam 21 rotates, it does not participate in the opening and closing operations of the intake valves 9 ₁ and 9 ₂ at all. It is something.

When the internal combustion engine 1 rotates at low speed from this state,
As described above, since the hydraulic pressure in the hydraulic chamber 25a is released, the first pin 24 and the second pin 29 slide in the other direction due to the biasing force of the spring 30, causing both pins 24 and 29 to come into contact with each other. The contact surfaces are both rotsuka arms 15 and 16.
Located at the boundary between each other, both rocker arms 15,1
6 is in a non-linked state. Therefore, the low speed cam 21
The main rocker arm 15, which has a slipper 18 in sliding contact with the main rocker arm 15, rotates with the rotation of the low-speed cam 21, and both intake valves ₉₁ and ₉₂ open and close according to the low-speed cam 21, and come into sliding contact with the high-speed cam 22. Slipper 19
Although the auxiliary rocker arm 16 rotates with the rotation of the high-speed cam 22, it does not participate in the opening/closing operation of the intake valves 9 ₁ and 9 ₂ at all.

In addition, the valve operation control device 1 on the exhaust valves 10 ₁ and 10 ₂ side
2, the operation is the same as that of the valve operation control device 11 on the intake valves 9 ₁ and 9 ₂ described above.

(Effects of the Invention) As detailed above, the internal combustion engine valve operation control device of the present invention provides the following effects.

() Valve opening/closing control is possible without separating the cam-side rocker arm and the valve-side rocker arm, which simplifies the valve operating mechanism, reducing power loss and making the structure more compact. It will be planned.

() Since the intake and exhaust valves are opened and closed directly by the valve drive member, engine operation is not always disturbed even if the connection switching means is inoperative.

() Although the structure is simple and compact, as shown in the horsepower characteristic diagram in Figure 5, higher output can be obtained over the entire rotation range of the internal combustion engine from low speed to high speed compared to the conventional valve stop system. This has the effect of being able to do the following.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional view of the valve actuation control device for an internal combustion engine of the present invention,
Figure 3 is a partially cutaway plan view of the valve actuation control device on the intake valve side, Figure 4 is a profile curve diagram of the high-speed cam and low-speed cam, and Figure 5 is the conventional and original It is a horsepower characteristic diagram with the invention. 1... Internal combustion engine, 9, _{9 1} , 9 ₂ ... Intake valve, 1
0, 10 ₁ , 10 ₂ ... exhaust valve, 11, 12 ... valve operation control device, 15 ... main rocker arm (first valve drive member), 16 ... sub-rocker arm (second valve drive member), 20...Camshaft, 21...Low speed cam (first cam), 22...High speed cam (other cam), 23...Connection switching means, 24...First pin (plunger), 25, 28... Fitting hole (cylinder).

Claims (1)

[Scope of Claims] 1. A camshaft that has a plurality of cams with different profiles for intake valves or exhaust valves provided for each cylinder, and is rotationally driven in synchronization with the rotation of the engine;
a first valve drive that contacts both one of the plurality of cams and the intake valve or the exhaust valve and directly drives the intake valve or the exhaust valve to open or close in response to the rotational movement of the one cam; and a second valve drive member that abuts another cam of the plurality of cams, the first and second valve drive members being displaced relative to a state in which they are integrally connected. 1. A valve operation control device for an internal combustion engine, characterized in that a connection switching means is provided for selectively switching between the two states. 2. The connection switching means includes a cylinder that accommodates a plunger in the first and second valve driving members,
The valve operation control device for an internal combustion engine according to claim 1, wherein the plunger is configured to be movable from one valve drive member to the plunger of the other valve drive member so as to be able to move in and out of the plunger. .