JPH0245455Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a valve train system for an internal combustion engine, and more specifically, an intake/exhaust system in which only a desired intake/exhaust valve out of the intake/exhaust valves operated by a rocker arm is inoperable at a predetermined time. This invention relates to a mechanism for stopping valve operation.

BACKGROUND OF THE INVENTION Various mechanisms are known in the art for variably controlling the displacement of a multi-cylinder internal combustion engine in accordance with the load and for stopping the operation of intake and exhaust valves corresponding to desired cylinders in order to deactivate only the desired cylinders.

Among such known intake/exhaust valve operation stop mechanisms, the structure closest to the present invention is disclosed, for example, as shown in U.S. Pat. The first arm is separated into two arms, the second arm is brought into contact with the valve stem, and relative sliding rotation is caused between these two arms when the intake/exhaust valve is temporarily inoperable or when reducing the valve lift. There are known valve lift absorbers. A male and female fitting part that can be engaged and disengaged is provided between both arms, and one of these male and female parts is actuated by a suitable actuator (such as a solenoid) to bring both arms to a lock position or an unlock position. . However, in all such conventional intake/exhaust valve operation stop mechanisms, the direction of action of the actuator's force is parallel to the axis of the rocker arm shaft, that is, the direction that pushes the first arm and the second arm apart. The two arms, which should originally be in surface contact, become separated, which could lead to eccentricity of the two arms or misalignment of the contact position between the arms and the valve stem.

Problems to be Solved by the Invention Therefore, in view of the prior art as described above, the problem to be solved by the invention is to solve the problem of the eccentricity of the rocker arm and the locker arm in a valve train having a so-called swing type (end pivot type) two-part rocker arm. The purpose of this invention is to provide a clear guideline for realizing a simple structure of a deactivation mechanism for intake and exhaust valves without causing misalignment of the contact position with the valve stem. .

Means for Solving the Problems In order to solve the above-mentioned problems, a swing arm-type rocker arm is provided, one end of which is rotatably supported on a rocker shaft, and the other end of which is brought into contact with the valve stem of an intake and exhaust valve; In a valve train for an internal combustion engine, the locker arm has a cam that is brought into contact with the intermediate portion of the locker arm and swings about the locker shaft as a fulcrum, and the locker arm is connected to the first arm on the side that is pivotally supported by the locker shaft and the valve stem. The first and second arms have a common fixed shaft extending parallel to the rock shaft, and the first and second arms are relatively rotatable around the fixed shaft. The two arms are freely connected to each other, so that both arms can selectively assume an operating position in which both arms extend integrally and an inoperative position in which they are bent about a fixed axis, and furthermore, the first and second arms are connected to each other. a lock pin that prevents relative rotation of both arms and integrally locks both arms in an operating position; and a cylinder type actuator that releases the lock pin at a predetermined time.
A return means is provided for constantly biasing both arms toward the operating position and returning both arms to the operating position when the lock is released, and the actuator has a stepped hole formed in one of the first arm and the second arm. a stepped piston that slides in the stepped hole; a cylinder chamber formed on the end surface of the large diameter portion opposite to the small diameter portion of the piston; The lock pin is drawn into a cylindrical hole formed in the other of the first arm and the second arm in a direction perpendicular to the axis of the lock shaft. and a position where the stepped hole protrudes from the cylindrical hole, and a recess is formed at the open end of the stepped hole to engage with the tip of the lock pin when the lock pin is in the protruded position. In an internal combustion engine, further characterized in that a back cylinder chamber is formed between the small diameter portion of the piston and the stepped hole, and is opened to the atmosphere through an exhaust passage opening on an inner circumferential wall surface of the stepped hole. A mechanism for deactivating the intake and exhaust valves is provided.

Embodiments Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

1 to 4 show a valve train of an internal combustion engine according to a first embodiment of the present invention, in which a rocker arm 11
The first arm 13A is rotatably connected to the rock shaft 19, and the first arm 13A is overlappingly connected to the first arm 13A through a fixed shaft 15 so as to be relatively rotatable, and is brought into contact with the valve stem 21 of the intake and exhaust valve. 2
It is composed of an arm 13B. That is, the conventional rocker arm is separated into two independent arms. The fixed shaft 15 extends parallel to the rocker shaft 19 or the camshaft 25.

A cam 23 mounted on a camshaft 25, which is rotated synchronously by a crankshaft (not shown) as is well known, is brought into contact with the intermediate portion of the rocker arm 11 in order to operate the rocker arm 11. In the illustrated embodiment, the cam 23 is the first arm 13A.
Although it is brought into contact with the vicinity of the tip of the second arm 13B, it may be brought into contact with the middle part or the vicinity of the rear end of the second arm 13B. As clearly shown in FIG. 2, the fixed shaft 15 extends through the overlapping arms 13A, 13B in a relatively rotatable manner.
B slides and rotates relatively around this fixed shaft 15, and can take an operating position shown in FIGS. 3 and 4 and an inoperative position shown in FIG. 1. When the first and second arms 13A, 13B are in the operating position, they are integrated as described below and cannot rotate relative to each other. That is, in the operating position, the first arm 13
A, the second arm 13B is completely equivalent to one integrated conventional rocker arm. On the other hand, when the first and second arms 13A, 13B are in their inoperative positions, the second arm 13B can rotate relative to the first arm 13A about the fixed shaft 15, as shown in FIG. When actuated by the cam 23, it can assume a bent state. Furthermore, 1
2 and 14 are a retainer attached to the valve stem 21 and a return spring for the intake and exhaust valves (not shown), respectively.

A return spring 29 is provided between the first arm 13A and the second arm 13B, and as the rocker arm 11 is pushed and bent by the cam protrusion 24 of the cam 23 as shown in FIG. 1, as the cam 23 rotates. When the cam protrusion 24 is disengaged from the locker arm 11, the locker arm 11 is moved to the operating position shown in FIGS. 3 and 4 (in the operating position, both arms 13A and 13B are
(It extends straight like the arm of a book).

For example, one end of the return spring 29 is connected to the first arm 1.
Although it is shown as a leaf spring that is fixed to a pin 32 implanted in the second arm 13A and has its other end locked to a pin 34 implanted in the second arm 13B, it is separately connected between both arms. Of course, a coil spring or the like may also be used.

The first arm 13A and the second arm 13B contact each other perpendicularly to the fixed shaft 15 at a boundary surface 38 (FIG. 2) so as to be able to slide and rotate. Also, the first arm 13
As shown in FIG. 1, the other surface 36 where A and the second arm 13B border is an arcuate surface that is equal to the trajectory of the arcuate motion when the second arm 13B rotates around the fixed shaft 15. There is. That is, the second arm 13B is rotatable about the fixed shaft 15 while sliding on and in contact with the arc-shaped receiving surface 36 formed on the first arm 13A.

A lock pin 45 for preventing relative rotation between the first arm 13A and the second arm 13B is slidably fitted into a blind hole 41 formed in the second arm 13B by a return spring 43. The locking pin 45 is formed, for example, as a movable piston having a substantially U-shaped cross section as shown in FIG. 2, and is buried in the blind hole 41 when the locking arm 11 is in the non-operating position, that is, in the unlocked state. Lock pin 4
An actuator for operating the arm 5 is constituted by a piston 33 slidably fitted into a cylinder 31 formed within the first arm 13A. The piston 33 is located at a position facing the lock pin 45, and is in contact with the lock pin 45 at the interface 36 between the first arm 13A and the second arm 13B when the locker arm 11 is in the inoperative position, that is, when the lock pin 45 is in the lock release position. Therefore, in this unlocked position, the second arm 13B can slide and rotate relative to the first arm 13A about the fixed shaft 15. The working cylinder chamber 30A of the cylinder 31 is connected to the bore 20 of the hollow rocker shaft 19 via a hydraulic passage 16 formed in the first arm 13A. The hollow bore 20 of the rock shaft 19 is a pressure oil supply device 5 having a pump P etc.
0, pressure oil at a predetermined pressure is supplied via the switching valve 60. The switching valve 60 receives, for example, an engine load signal S.
For example, an ordinary electromagnetic two-way switching valve may be used to switch between supplying the pressure oil from the pressure oil supply device 50 to the rock shaft or returning it to the drain depending on the situation.

When the locking pin 45 is in the locked position, the pressure oil in the hollow bore 20 of the locking shaft 19 is released;
Therefore, the lock pin 45 pushes the piston 33 into the cylinder 31 by the spring 43 and enters into the groove 48 coaxial with the cylinder 31 formed in the first arm 13A. As a result, lock pin 4
5 straddles both the first arm 13A and the second arm 13B, and the two arms are thus integrated and can no longer be slid and rotated relative to each other. Furthermore, when the piston 33 is pressed toward the lock pin 45 by the hydraulic pressure in the working cylinder chamber 30A of the cylinder 31, its shoulder portion causes the piston 33 to protrude forward from the interface between the first arm and the second arm. It seems like there is no such thing.

In the above configuration, according to the present invention, an exhaust passage 40 that is open to the atmosphere is provided in the back cylinder chamber 30B of the cylinder 31, which faces the working cylinder chamber 30A with the piston 33 in between. The volume of the back cylinder chamber 30B gradually decreases as the piston 33 moves forward toward the lock pin. Therefore, without the exhaust passage 40, the pressure within the back cylinder chamber 30B would gradually increase, acting as resistance or braking force against the movement of the piston 33. Therefore, such a piston 3
In order to eliminate the resistance force of 3 and enable smooth movement of the piston with small operating pressure, a passage 40 is provided in the back cylinder chamber 30B as an air release port.
It has been established.

In the embodiment shown in FIG. 1, the passageway 40 is preferably formed downwardly within the body of the first arm 13A. It is advantageous to have the passage 40 facing downward because the hydraulic oil around the piston is drained to the outside through it, and oil does not accumulate in the cylinder chamber.

The intake/exhaust valve operation/stop mechanism configured as described above operates as follows.

First, in the locked position of the lock pin 45, that is, in the operating position of the rocker arm 11 (FIGS. 3 and 4), no hydraulic pressure acts on the operating cylinder chamber 30A of the cylinder 31, and the lock pin 45 pushes the piston 33 into the groove 48. Partially inserted both arms 13
Since A and 13B are integrated, they operate in exactly the same way as the prior art. i.e. intake and exhaust valves (not shown)
When the valve is opened, as shown in FIG. 4, the lift of the cam projection 24 of the cam 23 is transmitted to the valve stem 21 via the rocker arm 11, and the valve stem 21 is pushed down to open the intake valve or exhaust valve. cam 23
When the cam protrusion 24 is removed from the rocker arm 11, the valve stem 21 is pushed up again by the spring 14 to close the valve.

Next, for example, when a predetermined intake/exhaust valve is to be inactivated at a predetermined engine load, pressure oil is supplied from the pressure oil supply device 50 into the cylinder 31, and the piston rod 33A of the piston 33 is connected to the lock pin 45.
is pushed into the blind hole 41 against the spring 43 to release the lock. As a result, the first arm 13A and the second arm 13B are independently separated and can freely rotate relative to each other. Therefore, when the rocker arm 11 is pushed down by the cam protrusion 24 of the cam 23, the rocker arm 11
bends as shown in Figure 1 to absorb the lift of the cam protrusion. Therefore, even though the cam 23 continues to operate, its movement is not transmitted to the valve stem 21, and the intake valve or exhaust valve remains inoperative (remains closed). When the rocker arm 11 is in the bent state as shown in FIG. 1, the lock pin 45 is removed from the piston 33 but is still held at the unlocked position by the receiving surface 36 of the first arm 13A. Each time the cam protrusion 24 of the cam 23 comes off the locker arm, the locker arm 11 is moved to the first position, which is the same as the operating position, by a return spring 29.
The second arm is returned to its straightened position.

5 and 6 show a second embodiment of the present invention, which differs from the first embodiment in that the exhaust passage 70 is formed parallel to the piston rod 33A and is open in the recess 48. different. That is, the passage 70 is formed in a wall portion 72 of the first arm 13A that forms the pivot portion of the piston rod 33A. It is possible, but not necessary, for the recess 48 itself to be open to the atmosphere by a separate passage (not shown).

FIG. 7 shows yet another embodiment, in which the exhaust passage 80 is formed as a part of the shaft hole of the piston rod 33A formed in the wall portion 72. In this case, the passage 80 may be, for example, a cutout groove with a U-shaped cross section.

In the embodiment shown in FIG. 8, the back cylinder chamber 30B
A second return spring 90 for the piston 33 is provided therein. That is, a second return spring 90 is provided in addition to the first return spring 43 for the lock pin 45, so that the return movement of the piston 33 when the hydraulic pressure is released can be performed more quickly.

Effects of the Invention As described above, according to the present invention, one end is rotatably connected to the rock shaft, the other end is locked to the valve stem of the intake and exhaust valve, and a cam is locked in the center, and the rock shaft is rotated by the cam. In a valve train having a rocker arm in the form of a so-called swing arm, which can be swung about a fulcrum, a simple and highly reliable intake/exhaust valve operation stop mechanism can be realized. Furthermore, according to the present invention, an exhaust passage is provided in the back cylinder chamber of the cylinder of the cylinder type actuator that releases the lock pin to release the air inside when the piston moves, so that almost no resistance force acts on the piston. The piston moves smoothly, allowing smooth switching between valve operation and stop.

[Brief explanation of the drawing]

FIG. 1 is an illustrative diagram showing the intake/exhaust valve operation stop mechanism according to the present invention in the unlocked position (inoperative position);
Fig. 2 is a sectional plan view of the main part of Fig. 1, Fig. 3 is a diagram showing the lock position (operating position) of the device shown in Fig. 1 when the valve is closed, and Fig. 4 is a diagram showing the lock position (operating position) of the device shown in Fig. 1 when the valve is open.
FIG. 5 is a view similar to FIG. 2 showing a second embodiment of the present invention, FIG. 6 is a sectional view taken along the line -- of FIG. 5, and FIGS. 7 and 8 are views of the present invention. Yet another 2 of
FIG. 2 is a diagram similar to FIG. 2 showing two embodiments; 11... Rotsuka arm, 13A... First arm, 13B... Second arm, 15... Fixed axis, 1
9...Rotsuka shaft, 21...Valve stem,
23...cam, 29...return spring, 30A...operating cylinder chamber, 30B...back cylinder chamber, 31
...Cylinder, 33...Piston, 40...Exhaust passage, 45...Lock pin.

Claims (1)

[Scope of utility model registration request] A swing arm-type rocker arm has one end rotatably supported by the rocker shaft and the other end abuts against the valve stem of the intake and exhaust valve, and the rocker arm is brought into contact with an intermediate portion of the rocker arm and swings about the rocker shaft as a fulcrum. In a valve train for an internal combustion engine, the locker arm has two separate arms: a first arm that is supported by the locker shaft, and a second arm that is in contact with the valve stem. The first and second arms are connected by a common fixed shaft extending parallel to the rock shaft so as to be relatively rotatable about the fixed shaft, so that both arms are in an operating position where both arms extend integrally. and an inoperative position bent about the fixed axis, and furthermore, a device is provided between the first and second arms to prevent relative rotation of both arms and to bring both arms into the operating position. A lock pin that locks integrally, a cylinder type actuator that releases the lock pin at a predetermined time, and a return means that constantly biases both arms toward the operating position and returns both arms to the operating position when the lock is released. , the actuator includes a stepped hole formed in one of the first arm and the second arm, a stepped piston that slides within the stepped hole, and an end surface of the large diameter portion of the piston opposite to the small diameter portion. The lock pin is formed in a cylindrical hole formed in the other of the first arm and the second arm. in the direction perpendicular to the axis of the shaft,
A lock pin is provided at an open end of the stepped hole to be movable between a position retracted into the cylindrical hole and a position protruded from the cylindrical hole, and a lock pin is provided at the open end of the stepped hole when the lock pin is in the protruded position. A recess is formed to engage with the tip of the piston, and a back cylinder chamber is formed between the small diameter portion of the piston and the stepped hole, and is vented to the atmosphere by an exhaust passage opening on the inner circumferential wall of the stepped hole. A mechanism for stopping the operation of intake and exhaust valves in an internal combustion engine, which is characterized by being opened.