JPH0366491B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve train for an engine, and more specifically, the present invention relates to a valve train for an engine, and more specifically, the present invention relates to a valve train for an engine.
The present invention relates to a valve train equipped with a valve deactivation mechanism that holds an exhaust valve in a closed position, that is, in an inoperative state, and stops operation of its cylinder.

(Prior Art) Conventionally, as disclosed in British Patent No. 1275328 and the drawings, for example, as disclosed in the specification and drawings of British Patent No. 1275328, as a valve train for an engine, a rocker arm of a specific cylinder is used as a cam-side arm that receives force from a camshaft. ,
It is divided into a valve-side arm that drives the intake and exhaust valves, and both arms are supported for relative rotational movement around the rocker shaft, and are movably supported by the cam-side arm and hydraulically connected to come into contact with the valve-side arm. A plunger that is pressed by a device is provided to limit the relative rotational movement of both arms approaching each other, transmitting the force from the camshaft to the valve-side arm, and driving the intake and exhaust valves to open and close by the valve-side arm. There is something like this. by the way,
In such a configuration, when the engine is in a low load range that does not require much engine output, by relieving the hydraulic pressure of the hydraulic system and eliminating hydraulic action on the plunger, both arms are rotated relative to each other and the camshaft is moved away from the camshaft. Reduced-cylinder operation is performed in which the force is not transmitted to the valve-side arm and the intake and exhaust valves are held in a closed position, that is, in an inoperative state, and the operation of a specific cylinder is stopped.This reduces the displacement in the low-load range. It is conceivable to reduce fuel consumption by reducing pumping loss as well as reducing pumping loss. In this case, during cylinder reduction operation, the only movable part of the valve train is the cam side arm, and its inertial mass is small.
Even if the engine speed becomes high, surging does not occur and the valve arm and the intake and exhaust valves do not jump, which is advantageous because it is possible to reliably stop the operation of a specific cylinder.

However, in the conventional system described above, it is necessary to provide a hydraulic device on the cam-side arm for pushing the plunger, and to form a hydraulic passage communicating with the hydraulic chamber of the hydraulic device on the cam-side arm or the rocker shaft. However, there are problems in that the structure of the valve train is complicated, making it difficult to process and increasing the cost. Furthermore, since the pressing force of the plunger is adjusted by hydraulic pressure, there is also the problem of poor responsiveness when switching between full-cylinder operation and reduced-cylinder operation.

Therefore, as a valve train to solve this problem, for example, as disclosed in Japanese Utility Model Application Publication No. 193903/1983, the cam side arm and the valve side arm, which are separated as described above, are connected to each other. The cam side arm is moved in the axial direction on the rocker shaft in the light load range of the engine, and the engagement with the valve side arm is released to allow both arms to rotate relative to each other.
A system has been proposed in which the intake and exhaust valves are kept in an inoperative state.

(Problem to be solved by the invention) However, in the above proposal, during all-cylinder operation,
Since both arms are simply engaged, there is a drawback that the engaged portion may come off during operation, making it impossible to operate with all cylinders, resulting in a lack of reliability. In addition, since the cam side arm itself must be moved in the axial direction on the rocker shaft, the equipment required for this movement becomes large-scale, and
The contact portion between the cam-side arm and the cam must be made wide in the axial direction of the rocker shaft in anticipation of misalignment due to the above-mentioned movement, which also poses the problem of high cost.

An object of the present invention is to control the relative rotational motion of the cam-side arm and the valve-side arm supported on the rocker shaft with a simple configuration as described above, thereby controlling the full-cylinder operation and reduced-cylinder operation. It is an object of the present invention to provide a valve train having a valve deactivation mechanism that operates reliably over the entire rotation range, has excellent responsiveness during switching, and is advantageous in terms of cost.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is such that a Rocker arm that presses the intake and exhaust valves of the engine to open them against the spring force of the valve springs. The rocker shaft supporting portion is divided into a cam-side arm that receives force from the camshaft and a valve-side arm that drives the intake and exhaust valves, and both arms are supported so as to be capable of relative rotational movement around the rocker shaft. The cam side arm and the valve side arm are supported by one of the arms so as to be movable forward and backward toward the other arm in a direction perpendicular to the axial direction of the rocker shaft, and come into contact with the other arm when advanced, and in this advanced state a plunger having an engaging portion in a portion supported by the one arm; and a spring biasing the plunger forward with a spring force smaller than that of the valve spring so as to bring the plunger into contact with the other arm. It is being Furthermore, the one arm has a locking part that is movably supported in the axial direction of the rocker shaft and is detachable from the engaging part of the plunger in the advanced state, and the locking part is connected to the engaging part of the plunger in the advanced state. A lock position in which the plunger is prevented from moving backward by engaging with the engaging portion and restricts the relative rotational movement of the two arms; A lever member is provided that is operated to allow the plunger to move backward against the biasing force of the spring and to a release position that allows relative rotational movement of both arms.

(Function) As a result, during all-cylinder operation, by moving the lever member in the axial direction of the rocker shaft and positioning it in the lock position, the relative rotational movement of both arms approaching each other is restricted, and the camshaft The force is transmitted to the valve-side arm, and the valve-side arm drives the intake and exhaust valves to open and close. On the other hand, during cylinder reduction operation, by moving the lever member in the axial direction of the rocker shaft and positioning it in the release position, the relative rotational movement of both arms is enabled, and the force from the camshaft is absorbed by the spring and the valve The intake and exhaust valves are held in a closed state, that is, in an inoperative state, by a valve spring without being transmitted to the side arm.

(Effects of the Invention) Therefore, according to the present invention, either the cam side arm or the valve side arm has a
A plunger is provided that comes into contact with the other arm, and a lever member is moved in the axial direction of the rocker shaft to change the position of the lever member, thereby preventing or permitting the backward movement of the plunger and relative rotational movement of both arms. As a result, the engine can be switched between full-cylinder operation and reduced-cylinder operation at the same time as the position of the lever member is changed, and responsiveness at the time of switching can be improved.
Since the backward movement of the plunger is reliably prevented or allowed, the reliability of each of the above operations can be improved. Furthermore, since a simple configuration of providing a lever member and a plunger on the arm is sufficient, cost reduction can be advantageously achieved.

Furthermore, since switching between full-cylinder operation and reduced-cylinder operation is performed by changing the position of the lever member by moving it in the axial direction of the rocker shaft, the position change is smooth and reliable, and it is possible to change the position perpendicularly to the rocker shaft. The structure is more compact than when the position is changed by, for example, and the inertial mass of the moving parts is reduced accordingly, making it possible to further contribute to the prevention of surging, thereby further improving the reliability mentioned above. It is something.

(Example) Hereinafter, an example as a specific example of the technical means of the present invention will be described based on the drawings.

FIG. 1 shows a first embodiment in which the present invention is applied to an in-line four-cylinder engine. H is a cylinder head disposed on a cylinder block (not shown). In the cylinder block, first to fourth cylinders C are formed at equal pitches in order from the front side (left side in FIG. 1). A camshaft 1 extending in the front-rear direction is disposed in the left-right center of the cylinder head H and is supported by rocker brackets R..., and the portions of the camshaft 1 corresponding to the cylinders C are provided with suction. , exhaust cam portions 2 and 3 are formed. Hollow rocker shafts 4, 4 extending parallel to the camshaft 1 are disposed on both left and right sides of the camshaft 1 and are supported by the rocker brackets R.

On the other hand, although not shown, the cylinder head H is formed with an intake port and an exhaust port corresponding to each cylinder C, and is also provided with an intake valve 5 and an exhaust valve 6 for opening and closing the intake and exhaust ports. It is being The intake and exhaust valves 5 and 6
is biased in the valve closing direction by a valve spring, and the upper ends of its stem portions protrude to the outside of the rocker shafts 4, 4 on both the left and right sides.

The rocker shafts 4, 4 on both the left and right sides are as follows:
Intake rocker arms 7 and 8 and exhaust rocker arms 9 and 10, which press and open the intake and exhaust valves 5 and 6 against the spring force of the valve spring, are rotatably supported. Each of the rocker arms 7 to 10 is provided such that its inner end abuts the corresponding cam portion 2, 3 of the camshaft 1, and its outer end abuts the upper end of the stem portion of the intake and exhaust valves 5, 6. As the camshaft 1 rotates, the cam portions 2 and 3 press the intake and exhaust valves 5 and 6 against the biasing force of the valve spring to open the valves at a predetermined timing. There is.

Of the rocker arms 7 to 10, the rocker arms 7 and 9 for intake and exhaust of the first cylinder C and the fourth cylinder C are provided with a valve deactivation mechanism, which is a main component of the valve train according to the present invention. . This valve deactivation mechanism will be explained with reference to the exhaust rocker arm 9 of the first cylinder C.As shown in detail in FIGS. Cam side arm 11 that receives force
and a valve-side arm 12 that presses and drives the exhaust valve 6.
1 and 12 are supported for relative rotational movement around the rocker shaft 4. The above cam side arm 11
A guide hole 13 is formed in the upper part of the rocker shaft 4 and extends in a direction perpendicular to the axial direction of the rocker shaft 4 and opens toward the valve side arm 12. It is supported so that it can move forward and backward relative to the arm 12. The plunger 14 is urged to advance so as to come into contact with the valve side arm 12 by a spring 15 which is installed in the guide hole 13 and has a spring force smaller than the spring force of the valve spring.

On the other hand, as shown in FIG. 1, a solenoid 16 is disposed at the rear of the cylinder head H, and an excitation shaft 17 is connected to the solenoid 16, which is pressed forward when the solenoid 16 is activated. There is. The excitation shaft 17 is guided into the hollow part of the rocker shaft 4, extends forward within the rocker shaft 4, and has its front end supported by the frontmost rocker bracket R so as to be slidable in the axial direction of the rocker shaft 4.

As shown in FIGS. 3 and 4, the parts of the rocker shaft 4 that support the rocker arms 7 and 9 for suction and exhaust are the rocker arms 7 and 9, as shown in FIGS.
A substantially rectangular insertion hole 18 is formed by cutting in the circumferential direction corresponding to the rotation angle.

A lock-off plate 19 as a lever member having a surface perpendicular to the guide hole 13 is attached to the cam-side arm 11 so that the lock-off plate 19 is attached to the rocker shaft 4.
The lower end of the lock-off plate 19 is connected to the excitation shaft 17 in the rocker shaft 4 through the insertion hole 18.
It is rotatably supported in a state where movement in the axial direction is restricted, and is locked by the biasing force of a return spring (not shown) that is installed inside the solenoid 16 and biases the excitation shaft 17 rearward. When the solenoid 16 is actuated, the lock-off plate 19 is placed in the forward release position.

Furthermore, the guide hole 1 is located in the middle of the plunger 14 and in the advanced state of the plunger 14.
3 is supported by an engaging portion 20 formed by notching the light diameter so that it becomes thinner, while a switching hole 21 is formed in the rocker-off plate 19 as shown in FIG. ing. The switching hole 21
A locking hole portion 21a is formed to be slightly larger than the shaft diameter of the plunger engaging portion 20 and serves as a locking portion that can be engaged and detached from the engaging portion 20, and a plunger is connected to the rear of the locking hole portion 21a. The insertion hole portion 21b is slightly larger than the shaft diameter of 14. When the lock-off plate 19 is positioned at the lock position due to the deactivation of the solenoid 16, as shown by the solid line in FIG. The plunger 14 is prevented from moving backward, and the plunger 14 protruding from the guide hole 13 presses the valve side arm 12 to restrict the relative rotational movement of the cam side arm 11 and the valve side arm 12 toward each other. The force received by the cam-side arm 11 from the camshaft 1 is transmitted to the valve-side arm 12 via the plunger 14 to open and close the exhaust valve 6, while the solenoid 16 is activated as shown by the imaginary line in FIG. When the lock-off plate 19 is positioned at the release position,
The insertion hole 21b is located coaxially with the plunger 14, allowing the plunger 14 to move backward and allowing relative rotational movement between the cam side arm 11 and the valve side arm 12.
1 transmits the force received from the camshaft 1 to the spring 15 by the backward movement of the plunger 14, absorbs it through compressive deformation of the spring 15, prevents the force from being transmitted to the valve side arm 12, and moves the exhaust valve 6 to the closed position. Configured to remain inactive. Incidentally, the intake rocker arm 7 is also configured with a valve deactivation mechanism similar to that of the exhaust rocker arm 9.

Therefore, in the medium load range or high load range of the engine, the first and fourth solenoids are not operated without operating the solenoid 16.
While cylinders C and C are operated to perform full-cylinder operation, in the low load range of the engine, the solenoid 16 is activated to stop the operation of the first and fourth cylinders C and C to perform reduced-cylinder operation. being done.

In addition, 22... and 23... are a coil spring and a leaf spring, respectively, which restrain the movement of the rocker arms 7 to 10 in the 4-axis direction of the rocker shaft.
24 is a sprocket that drives the camshaft 1, 25 is an adjustment screw for adjusting the valve brush, 2
6 is a plunger 14 in the valve side arm 12
This is the abutting part where the two abut against each other, and is made of a chip material with excellent wear resistance. 27 is a boss for installing a distributor, and 28 is a cylinder head cover.

Therefore, in the above embodiment, the operation or stopping of the first and fourth cylinders C and C can be freely switched, so that all-cylinder operation is sufficient in the medium load range or high load range of the engine. Generates engine output. On the other hand, in the low load range of the engine, cylinder reduction operation is performed to generate the required output while reducing the displacement by half, reducing fuel consumption, and halving the pumping loss to reduce horsepower loss, thereby increasing the fuel consumption rate. can be reduced.

At this time, the lock-off plate 19 is placed in the lock position or the release position to prevent or allow the plunger 14 to move backward, thereby switching between full-cylinder operation and reduced-cylinder operation. The responsiveness at the time of switching can be improved compared to the case where the configuration is as follows. Furthermore, during full-cylinder operation, the engagement between the locking hole 21a of the lock-off plate 19 and the engaging portion 20 of the plunger 14 reliably prevents the plunger 14 from moving backward, and during reduced-cylinder operation, the insertion hole 21b can reliably allow the plunger 14 to move backward, so each operation can be performed with high reliability.

Furthermore, during cylinder reduction operation, the only movable part of the valve train is the cam side arm 11, and the inertial mass of the movable part is small, so surging does not occur even when the engine speed becomes high, and the valve side Arm 12
Also, the intake and exhaust valves 5 and 6 do not jump. Therefore, the operation of the first and fourth cylinders C and C can be reliably stopped, cylinder reduction operation can be performed stably over the entire engine speed range, and the fuel consumption rate can be further reduced. I can do it.

Moreover, the switching between full-cylinder operation and reduced-cylinder operation is as follows:
The lock-off plate 19 is supported movably in the axial direction of the rocker shaft 4 at the upper part of the cam-side arm 11, and its position is changed between the lock position and the release position by the excitation shaft 17. The position of the lock-off plate 19 can be changed smoothly and reliably, and the upper structure of the cam-side arm 11 can be made as compact as possible. For example, the lock-off plate can be moved in a direction perpendicular to the rocker shaft 4. Since the increase in the inertial mass of the moving parts can be greatly suppressed compared to the case where the moving parts are supported by The reliability of each operation and switching between cylinder reduction operation and operation can be significantly improved.

In addition, since the structure is simple in that the guide hole 13 is formed in the cam side arm 11 to support the plunger 11 and the spring 15, and the lock-off plate 19 is provided whose position is changed by the solenoid 16, each member Compared to a structure in which a hydraulic chamber or a hydraulic passage is provided, it is easier to process and implement, and costs can be reduced.

Furthermore, FIGS. 5 and 6 show a second embodiment according to the present invention. In the first embodiment, the excitation shaft 17 is introduced into the rocker shaft 4 and the lock-off plate 19 is directly supported on the excitation shaft 17, but in the second embodiment, the support part of the valve side arm 12 and the rocker bracket R are connected to each other. A guide sleeve 29 is supported on the rocker shaft 4 between the rocker shafts 4 so as to be movable in the axial direction and urged toward the rocker bracket R side by a return spring 30, and a lock-off plate 19' is mounted on the upper surface of the guide sleeve 29.
Attach the end of the excitation shaft 17'
is supported on a rocker bracket R outside the rocker shaft 4, and the excitation shaft 17' is connected to a ring-shaped drive sleeve 31 supported between the guide sleeve 29 and the rocker bracket R. As a result, the lock-off plate 19', which is in the lock position, is moved to the release position via the drive sleeve 31 and the guide sleeve 29 when the solenoid 16 is actuated by the biasing force of the return spring 30. It has the same effect as the above. Note that 32 is a lock nut for adjusting the position of the excitation shaft 17'.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention,
Figure 1 is a plan view of the cylinder head, Figure 2 is the top view of the cylinder head.
3 is a sectional view taken along the - line in FIG. 2, FIG. 4 is a sectional view taken along the - line in FIG. 2, and FIGS. 5 and 6 show a second embodiment of the present invention. shows,
Figure 5 is a plan view of the cylinder head, Figure 6 is the top view of the cylinder head.
It is an enlarged view of the main part of the figure. 1...Cam shaft, 4...Rotskar shaft, 5...
...Intake valve, 6...Exhaust valve, 7, 8...Rotsuker arm, 9,10...Rotsuker arm, 1
1...Cam side arm, 12...Valve side arm,
14...Plunger, 15...Spring, 1
9, 19'... Lock-off plate, 20... Engaging portion, 21... Switching hole, 21a... Locking hole portion, 2
1b...Insertion hole portion, 29...Guide sleeve, 3
0... Return spring, 31... Drive sleeve.

Claims (1)

[Scope of Claims] 1. A Rocker arm that presses the intake and exhaust valves of the engine to open them against the spring force of the valve spring is connected to a cam-side arm that receives force from the camshaft at its Rocker shaft supporting portion. , a valve side arm that drives the intake and exhaust valves, and both arms are supported for relative rotational movement around the rocker shaft, and one of the cam side arm and the valve side arm has a rocker shaft. It is supported so as to be movable forward and backward toward the other arm in a direction perpendicular to the axial direction, and comes into contact with the other arm when advanced, and in this advanced state, an engaging portion is attached to the part supported by the one arm. a plunger having a plunger; a spring that urges the plunger to advance with a spring force smaller than that of the valve spring so as to bring the plunger into contact with the other arm; The engaging part of the plunger in the advanced state has a locking part that can be engaged with and detached from the engaging part of the plunger in the advanced state, and by engaging the locking part with the engaging part of the plunger in the advanced state, the backward movement of the plunger is prevented. By releasing the engagement between the locking position that restricts the relative rotational movement of both arms and the engaging part of the locking part, the plunger is allowed to move backward against the biasing force of the spring, and the two arms are moved. 1. A valve train for an engine, comprising: a lever member that is operated to move to a release position that enables relative rotational movement of the engine.