JPH0336130B2 - - 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 a valve train for an engine, for example, as disclosed in British Patent No. 1275328 and drawings, a rocker arm of a specific cylinder is connected to a cam-side arm that receives force from a camshaft, and
It is divided into a valve-side arm that drives the intake and exhaust valves, and both arms are supported so as to be movable relative to each other around the rocker shaft, and also supported movably on the cam-side arm so as to come into contact with the valve-side arm using a hydraulic device. A pressed plunger is provided, and when the engine is in a medium load range or a high load range, the plunger receives hydraulic pressure from the hydraulic system and comes into contact with the valve side arm, resulting in a relative movement in which both arms approach each other. There is a device in which the force from the camshaft is transmitted to a valve-side arm by limiting the amount of force, and the valve-side arm drives the intake and exhaust valves to open and close. By the way, in such a configuration, when the engine is in a low load range that does not require much engine output, the hydraulic pressure of the hydraulic system is released and the hydraulic action on the plunger is eliminated, causing both arms to move relative to each other and the camshaft. By preventing the force from being transmitted to the valve-side arm and holding the intake and exhaust valves in a closed position, that is, in an inoperative state, cylinder reduction operation is performed in which the operation of a specific cylinder is stopped.This reduces displacement in a low load range. It is conceivable to reduce fuel consumption by reducing pumping loss as well as reducing fuel consumption. In this case, during cylinder reduction operation, the only movable part of the valve train is the cam side arm, which has a small inertial mass, so surging does not occur even when the engine speed becomes high, and the valve side arm and intake and exhaust Since the valve does not jump, it is possible to reliably stop the operation of a specific cylinder, which is advantageous.

However, in the above-mentioned conventional device, 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. There are problems in that the structure of the valve train is complicated, difficult to process, and expensive. 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 of 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 move relative to each other. It has been proposed to keep the exhaust valve in an inoperative state.

However, in the above proposal, when operating all cylinders,
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 of the rocker shaft, the equipment required for this movement becomes large-scale, and the abutment part between the cam-side arm and the cam must be shifted by the amount due to the movement. Since it has to be made wider in the axial direction of the rocker shaft in anticipation of this, there is also the problem of high cost.

(Object of the Invention) The object of the present invention is to control the relative motion of the cam-side arm and the valve-side arm supported on the rocker shaft with a simple configuration as described above, thereby enabling 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 has excellent responsiveness when switching, is highly reliable, and is advantageous in terms of cost.

(Structure of the Invention) In order to achieve the above object, the solution means of the present invention is to combine a rocker arm that presses and opens intake and exhaust valves of an engine with a cam-side arm that receives force from a camshaft, and a cam-side arm that receives force from a camshaft. It is divided into a valve-side arm that drives the valve, and both arms are supported so as to be movable relative to each other around the rocker shaft. A plunger biased by a spring so as to come into contact with the arm, a first position that prevents movement of the plunger and limits relative movement of the arms, and a first position that allows movement of the plunger to allow relative movement of the arms. A lever member is provided to take the second position and the second position.

As a result, during all-cylinder operation, the lever member is positioned at the first position to limit the relative movement of both arms approaching each other, and the force from the camshaft is transmitted to the valve-side arm, thereby transmitting the force from the camshaft to the valve-side arm. While the arm closes the intake and exhaust valves, during cylinder reduction operation the lever member is positioned in the second position to enable relative movement of both arms, and the force from the camshaft is absorbed by the spring to close the valve side. without transmitting it to the arm,
The intake and exhaust valves are kept in a closed state, that is, in an inoperative state.

(Effects of the Invention) Therefore, according to the present invention, one of the cam-side arm and the valve-side arm is provided with a plunger that comes into contact with the other arm, and the position of the lever member is changed, thereby achieving the above-mentioned effect. Since the relative movement of both arms is controlled by blocking or allowing movement of the plunger, 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 the response when switching is In addition, since 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.

(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 an 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. At the portions of the camshaft 1 corresponding to the cylinders C, suction, Exhaust cam parts 2 and 3 are formed. 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, 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. 11 and a valve-side arm 12 that presses the exhaust valve 6.
1 and 12 are supported for relative movement around the rocker shaft 4. A guide hole 13 that opens toward the valve side arm 12 is formed in the upper part of the cam side arm 11.
A cylindrical plunger 14 is movably supported on the valve side arm 1 by a spring 15 installed in the guide hole 13.
It is biased so as to contact 2.

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 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. A ring-shaped drive sleeve 19 is supported between the guide sleeve 17 and the rocker bracket R.
An end portion of the lock-off plate 16 is attached to the upper surface of the guide sleeve 17.

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 a rocker bracket R.
The drive sleeve 1 is supported by the drive sleeve 1 and extends forward.
9, and the return spring 1
When the solenoid 20 is actuated, the lock-off plate 16, which is in the first locked position, is moved forward through the drive sleeve 19 and the guide sleeve 17 to the second unlocked position.

The middle part of the plunger 14 is notched to reduce the shaft diameter to form an engaging part 22, while the lock-off plate 16 is formed with a switching hole 23 as shown in FIG. There is. The switching hole 23 consists of a locking hole portion 23a that is slightly larger than the shaft diameter of the plunger engaging portion 22, and an insertion hole portion 23b that is connected to the rear of the locking hole portion 23a and 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. 14 is prevented from moving, and the plunger 14 protruding from the guide hole 13 presses the valve side arm 12 to close the cam side arm 11.
This restricts the relative movement of the cam-side arm 11 and the valve-side arm 12 toward each other, thereby transmitting the force received by the cam-side arm 11 from the camshaft 1 to the valve-side arm 12 via the plunger 14 to close the exhaust valve 6. While driving the lock-off plate 1 to open and close, the lock-off plate 1 is activated by the operation of the solenoid 20 as shown by the phantom line in FIG.
6 is positioned at the release position, the insertion hole 23b is positioned coaxially with the plunger 14, allowing movement of the plunger 14 and allowing relative movement between the cam-side arm 11 and the valve-side arm 12. As a result, the force received by the cam side arm 11 from the camshaft 1 is transmitted to the spring 15 by the movement of the plunger 14, and the force is absorbed by the compressive deformation of the spring 15 and not transmitted to the valve side arm 12, and the force is transmitted to the exhaust valve 6. is configured to maintain the switch in a closed or inoperative position. 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 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, and 26 is a sprocket that drives the camshaft.
is an adjustment screw for adjusting the valve brush,
27 is a lock nut for adjusting the position of the excitation shaft 21, 28 is a boss for attaching a distributor, and 29 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. While generating the required engine output, in the low load range of the engine, cylinder reduction operation is performed to generate the required output while halving displacement to reduce fuel consumption and halving pumping loss to reduce horsepower loss. , thus 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 movement of the plunger 14 to switch between full-cylinder operation and reduced-cylinder operation. It is possible to improve the responsiveness during switching compared to the case where the Furthermore, during full-cylinder operation, the movement of the plunger 14 can be reliably prevented by the engagement between the locking hole 23a of the lock-off plate 16 and the engaging portion 22 of the plunger 14, and during reduced-cylinder operation, the insertion hole 23b
Since the movement of the plunger 14 can be reliably allowed, 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. Can be done.

In addition, since the configuration is simple in that a guide hole 13 is formed in the cam side arm 11 to support the plunger 11 and the spring 15, and a lock-off plate 16 whose position is changed by the solenoid 20 is provided, 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.

In addition, since 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, the cam-side arm 11
The upper part can be made as compact as possible, and the increase in inertial mass of the movable parts can be greatly suppressed compared to, for example, the case where the lock-off plate is movably supported in a direction perpendicular to the rocker shaft 4. This is particularly advantageous in preventing surging in the high engine speed range.

[Brief explanation of the drawing]

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...Camshaft, 5...Intake valve, 6...Exhaust valve, 7, 8...Rotzker arm, 9, 10...
...Lotsuker arm, 11...Cam side arm, 12
... Valve side arm, 14 ... Plunger, 15
... Spring, 16 ... Lock-off plate,
22...Engaging portion, 23...Switching hole.

Claims (1)

[Claims] 1 The rocker arm that presses and opens the intake and exhaust valves of the engine 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 connected to the rocker shaft. the cam-side arm and the valve-side arm, and is movably supported on one of the cam-side arm and the valve-side arm;
and a plunger biased by a spring so as to come into contact with the other arm, a first position that prevents movement of the plunger and limits the relative movement of the two arms, and a first position that allows movement of the plunger and moves the two arms relative to each other. 1. A valve train for an engine, comprising: a lever member that assumes a second position that enables movement.