JPH0366490B2 - - 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. Furthermore, since the cam-side arm itself must be moved in the axial direction on the rocker shaft, excessive force is applied to each member during this movement. Moreover, the equipment required for the movement becomes large-scale, and the contact area between the cam-side arm and the cam must be made wide in the axial direction of the rocker shaft in anticipation of the displacement caused by the movement, which reduces cost. It also has the problem of being expensive.

An object of the present invention is to control the relative rotational movement of the cam-side arm and the valve-side arm supported on the rocker shaft with a simple configuration as described above, thereby achieving full-cylinder operation and reduced-cylinder operation in the entire rotation range. It is an object of the present invention to provide a valve train having a valve deactivation mechanism that performs each operation and switching between these operations with high reliability, 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 orthogonal 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 Further, a base end is slidably and rotatably supported by the rocker shaft, a distal end is movably supported by the one arm in the axial direction of the rocker shaft, and is engaged with the engaging portion of the plunger in the advanced state. A lock having a removable locking portion and engaging the locking portion with the engaging portion of the plunger in the advanced state to prevent the plunger from moving backward and restricting the relative rotational movement of the two arms. and a release position in which the engagement of the locking part with the engaging part is released, thereby allowing the plunger to move backward against the biasing force of the spring, thereby allowing relative rotational movement of the two arms. A lever member that can be moved and operated is provided.

(Function) As a result, during all-cylinder operation, by sliding the lever member on 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, which drives the intake and exhaust valves to open and close. On the other hand, during cylinder reduction operation, by sliding the lever member on 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 side The valve springs hold the intake and exhaust valves in a closed state, that is, in an inoperative state, without transmitting the signal to the 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 abuts the other arm, and a lever member slidably supported on the rocker shaft is moved in the axial direction of the rocker shaft to change its position, thereby preventing or allowing the plunger to move backward. Since the relative rotational movement of both arms is controlled, 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, improving responsiveness when switching. , the backward movement of the plunger is reliably prevented or allowed, and 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.

In addition, since the lever member is moved while being supported by the rocker shaft, the lever member is on the same axis (rocker shaft) as the arm that supports the plunger, and the rotational moment acting on the lever member during each operation can be applied. Therefore, it is possible to further improve the above-mentioned reliability and to improve the durability of the valve deactivation mechanism.

(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 as to be movable 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.

Further, a lock-off plate 16 as a lever member having a surface perpendicular to the guide hole 13 is supported on the upper part of the cam-side arm 11 at its tip side so as to be movable in the axial direction of the rocker shaft 4. . As shown in FIG. 4, a guide sleeve 17 movable in the axial direction is attached to the rocker shaft 4 between the support portion of the valve side arm 12 and the rocker bracket R by a return spring 18. The proximal end of the lock plate 16 is attached to the upper surface of the guide sleeve 17. Therefore, the lock-off plate 16 is connected to the rocker shaft 4 via the guide sleeve 17 at its base end.
is slidably supported on. A ring-shaped drive sleeve 19 is interposed between the guide sleeve 17 and the rocker bracket R.

On the other hand, as shown in FIG. 1, a solenoid 20 is disposed at the rear of the cylinder head H, and an excitation shaft 21 that is pressed forward when the solenoid 20 is activated is connected to the solenoid 20. . The excitation shaft 21 is supported by the rocker bracket R, extends forward, and is connected to the drive sleeve 19, and drives the lock-off plate 16 in the locked position by the biasing force of the return spring 18 when the solenoid 20 is activated. It is positioned at the forward release position via the sleeve 19 and guide sleeve 17.

The guide hole 1 is located in the middle of the plunger 14 and in the advanced state of the plunger 14.
An engaging portion 22 is formed in the portion supported by the holder 3, which is notched so that the light diameter becomes narrower.
On the other hand, a switching hole 23 is formed in the rocker-off plate 16 as shown in FIG. The switching hole 2
3 is a locking hole portion 23a formed slightly larger than the shaft diameter of the plunger engaging portion 22 and serving as a locking portion that can be engaged and detached from the engaging portion 22; and a locking hole portion 23a connected to the rear of the locking hole portion 23a. The insertion hole 23b is slightly larger than the shaft diameter of the plunger 14. When the lock-off plate 16 is positioned at the lock position due to the deactivation of the solenoid 20, as shown by the solid line in FIG.
4 to prevent the plunger 14 from moving backward, and the plunger 14 protruding from the guide hole 13 presses the valve side arm 12 so that the cam side arm 11 and the valve side arm 12 are mutually connected. As a result, the force received by the cam side arm 11 from the cam side 1 is transmitted to the valve side arm 12 via the plunger 14 to open and close the exhaust valve 6, while the fourth When the lock-off plate 16 is positioned at the release position by the operation of the solenoid 20, as shown by the imaginary line in the figure, the insertion hole 23b is positioned coaxially with the plunger 14, allowing the plunger 14 to move backward. This enables relative rotational movement between the side arm 11 and the valve side arm 12, thereby transferring the force received by the cam side arm 11 from the camshaft 1 to the plunger 14.
is transmitted to the spring 15 by the backward movement of the exhaust valve 6, and is absorbed by the compressive deformation of the spring 15 so that the exhaust valve 6 is not transmitted to the valve-side arm 12, and the exhaust valve 6 is held in a closed position, that is, in an inoperative state. . 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 20.
While cylinders C and C are operated to perform full-cylinder operation, in the low load range of the engine, the solenoid 20 is activated to stop the operation of the first and fourth cylinders C and C to perform reduced-cylinder operation. being done.

In addition, 24... is a coil spring that restrains the movement of the rocker arms 7 to 10 in the direction of the four axes of the rocker shaft, 25 is a sprocket that drives the camshaft 1, 26 is an adjuster screw for adjusting the valve brush, and 27 is a valve side arm 12. This part is in contact with the plunger 14 and is made of a chip material with excellent wear resistance. 28 is a lock nut for adjusting the position of the excitation shaft 21, 29 is a boss for attaching a distributor, and 30 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 16 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. Moreover, during full-cylinder operation, the engagement between the locking hole 23a of the lock-off plate 16 and the engaging portion 22 of the plunger 14 reliably prevents the plunger 14 from moving backward, and during reduced-cylinder operation, the insertion hole 23b 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 16 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 21. The position of the lock-off plate 16 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 movable parts can be greatly suppressed compared to the case where the movable parts are supported by the movable parts, this is advantageous in preventing surging, especially in the high rotational speed range of the engine. Therefore, the reliability of each operation between the full-cylinder operation and the reduced-cylinder operation as well as the switching between the operations 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 16 is provided whose position is changed by the solenoid 20, 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.

Moreover, the movement of the lock-off plate 16 for the above-mentioned position change is supported by the cam-side arm 11 supported by the rocker shaft 4, and supported by the rocker shaft 4 via a guide sleeve 17 on the side of the cam-side arm 11. Therefore, the lock-off plate 16 and the cam-side arm 11 are on the same axis (rocker shaft 4), and the supporting part of the lock-off plate 16 on the cam-side arm 11 and the mounting part on the guide sleeve 17 are connected to each other. are close to each other, and almost no rotational moment acts on the lock-off plate 16 during each operation. the result,
The lock-off plate 16 will not break,
The reliability of both operations can be further improved, and the durability of the valve deactivation mechanism can be improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a plan view of the cylinder head, FIG. 2 is an enlarged view of the main part of FIG. 1, FIG. 3 is a cross-sectional view taken along the line - FIG. 2 is a sectional view taken along the - line in FIG. 2; 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, 16
... Lock-off plate, 17 ... Guide sleeve, 22 ... Engagement part, 23 ... Switching hole, 23a ...
...Latching hole portion, 23b...Insertion hole portion.

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 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; and a base end slidably and rotatably supported on the rocker shaft. , a locking portion is provided at the distal end of the plunger, the locking portion being movably supported by the one arm in the axial direction of the rocker shaft and detachable from the engaging portion of the plunger in the advanced state; A lock position where the plunger is engaged with the engagement portion of the plunger to prevent the plunger from moving backward, thereby restricting the relative rotational movement of the arms, and the locking portion is disengaged from the engagement portion of the locking portion. and a lever member that is operated to move the plunger to a release position that allows the plunger to move backward against the biasing force of the spring and allows relative rotational movement of the two arms. Engine valve gear.