JPH0627491B2 - Engine valve drive - Google Patents

Description

TECHNICAL FIELD The present invention includes a lock mechanism for locking and unlocking a cam member for driving an intake valve or an exhaust valve with respect to a camshaft. The present invention relates to a valve drive device for an engine, which controls a lock mechanism according to an operating state and thereby controls valve operation.

(Prior Art) Conventionally, the operation of the intake valve and the exhaust valve is controlled according to the operating state for the purpose of improving the fuel efficiency performance and the output performance of the engine, thereby the intake and exhaust timing,
Alternatively, it is known to control the intake / exhaust amount.

For example, in Japanese Patent Laid-Open No. 59-155515, a double cam having two cam members integrally formed is formed.
An engine is disclosed which has a structure in which this dual cam member is loosely fitted to a cam shaft and is provided with a valve stop device for preventing relative rotation between the cam member and the cam shaft.

In this structure, when the engine has a relatively light load, the hydraulic pressure is introduced into the valve stop device to release the lock and permit the relative rotation of the dual cam member. That is, when the load is light, the double cam does not cause the valve to open, and the valve corresponding to the double cam is maintained in the closed state.

In this device, the valve stop device is provided with a plunger that slides in an engagement hole formed in the cam member and the cam shaft so that the cam member and the cam shaft can communicate with each other in the radial direction, and controls the entrance and exit of the plunger cam member side engagement hole. By doing so, the locking and unlocking of the cam member is controlled.

(Problems to be solved) In such a locking mechanism using a plunger, it is premised that the plunger is surely controlled to move into and out of the engagement hole, but the camshaft rotates at an extremely high speed. , It becomes difficult to ensure the operation. For this reason,
In order to make it easier for the plunger to enter the engagement hole on the cam member side, it is conceivable to form the engagement hole slightly larger than the diameter of the plunger. However, in this case, a gap is created between the plunger and the wall surface of the engagement hole, and as a result,
There is a problem that proper valve operating characteristics cannot be obtained.

(Means for Solving the Problem) The present invention is configured to solve the above problem, and can perform a reliable operation, and therefore can perform reliable valve control. , In the locked state, there is no rattling between the cam member and the cam shaft,
Therefore, it is an object of the present invention to provide a valve drive device provided with a lock mechanism that can provide appropriate valve operating characteristics.

The valve drive device of the present invention includes a cam shaft and a cam member rotatably attached to the cam shaft for driving an intake valve or an exhaust valve. A pair of engagement holes extending in the radial direction is formed on the cam member and the cam shaft so that they can communicate with each other at a predetermined rotational position of the cam member. The engagement hole on each cam member side is formed to have a slightly larger diameter than the engagement hole on the cam shaft side. Further, a spring and a first plunger biased by the spring are slidably arranged in the engagement holes of the respective cam members. The engagement hole on each camshaft side communicates with an oil passage formed inside the camshaft, and a second plunger is slidably arranged in the engagement hole on the camshaft side.
By controlling the hydraulic pressure to the oil passage in the cam shaft, the second plunger can move in and out of the engagement hole on the cam member side, thereby locking or unlocking the cam member on the cam shaft. It has become. When the second plungers enter the engagement holes on the cam member side, the engagement holes on the cam shaft side are engaged with the engagement holes on the cam member side so that the cam member cannot rotate relative to the cam shaft. It is arranged offset.

In a preferred aspect of the present invention, of the two engagement holes on the cam member side, one of the engagement holes has a side into which the second plunger enters, and guides the entry of the second plunger along the rotation direction. A run-up groove is formed, and a similar run-out groove is formed on the other side of the second engaging hole on the side where the second plunger escapes.

Further, although the pair of engagement holes according to the present invention can be formed for a cam member having a single cam surface, the cam member is constituted by a double cam member having two cam surfaces. , So as to have the above conditions corresponding to each cam surface,
You may install one by one. Further, the valve drive system of the present invention preferably includes a control valve for controlling the supply of hydraulic pressure to the oil passage. According to the structure of the present invention, the engagement hole on the cam member side and the engagement hole on the cam shaft side are formed at positions aligned in the axial direction of the cam shaft, that is, the two engagement holes are They communicate with each other in a predetermined circumferential direction, and at this time, the first plunger and the second plunger are in contact with each other. When the hydraulic pressure is introduced into the oil passage of the camshaft by the operation of the control valve when the first plunger and the second plunger are in contact with each other, the second plunger slides in the hole of the camshaft by the hydraulic pressure. The plunger is pushed against the biasing force of the spring to project into the hole of the cam member. As a result, the cam member is fixed to the cam shaft, that is, locked, and the relative rotation between the cam member and the cam shaft is prevented, and the cam member rotates together with the cam shaft, thereby enabling the valve drive by the cam member. Become.

In the present invention, the first plunger has a larger diameter than the second plunger, that is, the cam member side engagement hole is larger than the cam shaft side engagement hole. this is,
This structure is for facilitating the entrance and the exit of the second plunger into the cam side engagement hole. With this structure, in the locked state, there is a gap between the second plunger and the wall surface of the cam member side engagement hole. Because of the presence of, there is rattling of the cam member. In the present invention, two locking mechanisms are used in combination in order to solve the problem of rattling. That is, the positional relationship is determined so that the cam member side engagement hole and the cam shaft side engagement hole are in a state of being offset by the difference in diameter between them, for example, in the locked state. As a result, the two second plungers are brought into contact with the wall surface of the engagement hole when entering the engagement hole on the cam member side, that is, in the locked state, so that the cam member is positioned relative to the cam shaft. It is fixed so that it cannot rotate.

Furthermore, according to the present invention, the control valve for controlling the hydraulic pressure to the oil passage in the camshaft is controlled according to the operating state of the engine, whereby the cam member can be locked or unlocked. Is controlled.

By using the above locking mechanism according to the present invention, a plurality of cam members can be provided for one valve and the cam members can be selectively contributed to the operation of the valve. In this case, the plurality of cam members are respectively provided. By configuring the cam members to have different cam profiles and selectively actuating the cam members as appropriate, different valve opening timings depending on operating conditions,
The valve opening period and the valve lift amount can be given.

Further, the cam member of a specific cylinder can be configured to be rotatable with respect to the cam shaft using a lock mechanism so that the valve operation of the cylinder can be controlled at a constant operating condition. You can also stop completely.

(Effect of the Invention) According to the present invention, as described above, in the lock mechanism using the plunger, the cam member side engagement hole that engages with the locking plunger has a larger diameter than the plunger. ,
It is extremely easy for the plunger to move in and out, so that reliable valve drive control can be performed. In this case, in the structure of the present invention, a pair of lock mechanisms of similar structure are used in combination, and the cam member side engagement hole and the cam shaft side engagement hole of each lock mechanism are locked. In this state, the locking plunger is in contact with the wall surface of the engagement hole, so that the cam member is fixed to the cam shaft in a completely non-rotatable manner. Therefore, it is possible to solve the problem of rattling of the cam member due to the clearance provided to obtain the operability. Further, when the running groove is provided in the cam member side engagement hole along the rotation direction of the cam shaft, the plunger can be more easily inserted into and removed from the engagement hole, further improving the certainty of operation. You can In addition, the present invention is DOH
It can be applied to both C and SOHC and also to an engine that performs cylinder deactivation operation, and is excellent in versatility.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Referring to FIGS. 1 and 2, the engine includes a valve drive device that opens and closes a valve 1 facing the combustion chamber. The valve drive device includes a camshaft 5 rotatably supported by a journal portion formed by the cylinder head 2 and the cap 3 via a liner 4 on the upper portion of the engine. Two cam members 6 and 7 for driving the valve 1 are attached to the cam shaft 5 of this example. In this case, the two cam members 6, 7 are configured to have different cam profiles and the cam member 7 with the larger cam profile is pivotable with respect to the camshaft 5, while the cam members 6 are Is permanently fixed. The valve 1 is slidably supported by the cylinder head 2 via a valve guide 8 at an intermediate portion of the valve stem 1a. Further, the coil spring 1 is provided between the spring retainer 9 mounted near the tip of the valve stem 1a and the seat surface 2a formed on the cylinder head 2.
0 is disguised. Further, the valve bucket 11 is attached so as to cover the top of the valve stem 1a,
The cam surfaces of the cam members 6 and 7 are in sliding contact with the top surface of the bucket 11. In this case, the cam member 7 is controlled by the lock mechanism 12, and when the lock mechanism 12 operates, the cam member 7 is restrained from rotating relative to the cam shaft 5 and rotates together with the cam shaft. Come to do. In this state, the cam profile of the cam member 7 is larger than the cam profile of the cam member 6, so that the cam member 7 has priority and drives the valve 1. In the present example, the cam member 7 is adapted to be locked in the high speed region, so that the cam member 6 functions as a low speed cam and the cam member 7 functions as a high speed cam.
Further, in this example, the cam member 7 is formed wider than the cam member 6 so that the contact surface pressure of the cam member 7 which gives a large valve lift amount with the valve bucket 11 is not higher than that of the cam member 6. is doing. Also, the high speed cam member 7
The offset amount from the central axis 13 in the operating direction of the valve 1 is arranged so as to be smaller than that of the cam member 6, and the eccentric load applied to the valve stem 1a is minimized. The movement of the cam member 7 in the camshaft axial direction is disabled by the locking pin 14. As shown in FIG. 1, the hydraulic pressure for controlling the cam member is introduced from the oil pump 23 to the oil filter 25 provided in the hydraulic passage 24 and the hydraulic passage 27 formed in the journal portion via the control solenoid valve 26. Then, it is introduced into the hydraulic chamber 22 through a through hole 28 formed in the journal portion in the radial direction. The solenoid valve 26 is preferably controlled by an electronic controller 30 including a microcomputer, and switches the introduction or release of the oil pressure from the oil pump 23 into the oil pressure chamber 22. It has become. The solenoid valve returns oil from the return port 26a to the oil pan 31 when the hydraulic pressure is not introduced into the hydraulic chamber 22. Signals such as engine speed and engine load are input to the controller 30.
0 is the solenoid 2 of the solenoid valve 26 based on this input signal.
A command signal is output to 6b, and the solenoid valve 26 is switched.

Referring also to FIG. 3, lock mechanisms 12a and 12b are provided for controlling locking and unlocking of the cam member 7. Since the lock mechanisms 12a and 12b have the same structure, only the lock mechanism 12a will be described, and the lock mechanism 12b will be denoted by the corresponding reference numeral and description thereof will be omitted. The lock mechanism 12a includes a cam member side plunger fitted in an engagement hole 7a formed in the cam member 7, that is, a first plunger 16a and the first plunger 16a.
spring 17a compressed between a and the end surface of the engagement hole 7a
And a second plunger 18a, which has a smaller diameter than the first plunger 16 and fits into an engagement hole 5a formed in the camshaft 5 in the radial direction. The lock mechanism 12a is operated by hydraulic pressure, and when the hydraulic pressure is introduced into the hydraulic chamber 22 formed by partitioning the oil passage 19 formed along the rotation axis of the camshaft with the plug 20, The second plunger 18a pushes the first plunger 16a against the elastic force of the spring 17a, and the trailing side of the engagement hole 7a, that is, the second plunger 18a pushes the first plunger 16a along the rotation direction of the inner surface of the cam member.
The plunger 18a moves in sliding contact with the running groove 27a formed on the entry side of the plunger 18a and enters the cam side engagement hole 7a.

The lock mechanism 12b is arranged so as to be separated from the lock mechanism 12a by a certain distance in the rotation direction, and similarly, the lock mechanism 12b is also arranged.
When the hydraulic pressure is introduced into 2, the plunger 16b projects into the engagement hole 7b. That is, the lock mechanisms 12a, 12
b operates synchronously, and the cam member 7 operates when the second plungers 18a, 18b enter the engagement holes 7a, 7b.
It will be locked and unlocked when you escape. In addition, the run-up groove 27b of the lock mechanism 12b is formed in
It is provided on the leading side of b, that is, on the escape side of the second plunger 18b. Further, in the structure of the present invention, the distance between the center lines of the engagement holes 7a and 7b and the distance between the center lines of the engagement holes 5a and 5b are the same as the engagement holes 7a and 7b and the engagement holes 5a and 5b.
The difference is the difference in the diameter of b. That is, in the locked state, the wall surfaces of the engagement holes 7a, 7b and 5a, 5b are flush with each other inside or outside,
Camshaft side engagement holes 5a, 5b and cam member side engagement hole 7
An offset positional relationship with a and 7b is determined. Therefore, when the second plungers 18a, 18b enter into the cam member side engagement holes 7a, 7b and are locked, the plungers 18a, 18b are brought into contact with the wall surfaces of the engagement holes 7a, 7b. As a result, the relative rotation of the cam member 7 with respect to the cam shaft 5 is completely disabled.

In this example, when the engine speed is high, hydraulic pressure is introduced into the hydraulic chamber 22, and the camshaft side plungers 18a and 18b enter the engagement hole 7a on the cam member side by the hydraulic pressure to lock the cam member 7.

According to the structure of this example, the cam member side engagement holes 7a and 7b are
It is formed with a diameter larger than that of the second plungers 18a, 18b, and the run-up groove 27 is formed around the engagement holes 7a, 7b.
Since the a and 27b are formed, the second plunger 18
It is easy for the a and 18b to enter and leave the engaging holes 7a and 7b, and therefore, reliable locking and unlocking operations can be performed. Also, the cam member side engagement holes 7a, 7b
Since the positional relationship between the camshaft side engagement holes 5a and 5b and the camshaft side engagement holes 5a and 5b is determined so as to have a constant offset amount, in the locked state, the second plungers 18a and 18b are provided.
Although there is a difference in diameter between the engagement holes 7a and 7b,
A good locked state between the cam member 7 and the cam shaft can be obtained. As a result, the structure of this example can provide appropriate valve drive control according to the operating state.

Referring to FIG. 4, there is shown another embodiment of the present invention, in which the cam member 37 has two cam portions 38 and 39 for driving the valves 1 of different cylinders.
It is configured as a continuous cam member and is loosely fitted on the cam shaft 5 as in the previous example. The description of the structure of the present example will be given only for the points different from the previous example, and for the common parts, the same reference numerals will be given to corresponding members and the description thereof will be omitted. The cam member 37 has cam portions 38 and 39 at both ends and a bearing portion 37a supported by the cylinder head 2 at the center. The cam portions 38 and 39 are respectively provided with the same lock mechanisms 12a and 12b as in the previous example. The two lock mechanisms are arranged in the same positional relationship in the rotation direction as in the previous example, and in the locked state, the two lock mechanisms 12a and 12b cooperate with each other to form the cam member 3.
7 is fixed to the camshaft 5 so as not to rotate. Therefore, also in the structure of this example, the same effect as that of the previous example can be obtained.

[Brief description of drawings]

1 is a partial cross-sectional view of an engine according to an embodiment of the present invention, FIG. 2 is a detailed view of a cam member of the embodiment of FIG. 1, FIG. 3 is a detailed view of a lock mechanism, and FIG. FIG. 6 is a partial cross-sectional view of a valve drive device according to another embodiment of the present invention. 1 ... Valve, 1a ... Valve stem, 2 ... Cylinder head, 3 ... Cap, 5 ... Cam shaft, 6, 7, 37 ... Cam member, 12a, 12b ... Lock mechanism, 16a, 16b, 18a, 18b ... Plunger, 22 ... Hydraulic chamber, 26 ... Solenoid valve, 30 ... Controller.

Claims (1)

[Claims] 1. A cam shaft, and a cam member rotatably attached to the cam shaft for driving an intake valve or an exhaust valve. The cam member and the cam shaft have a predetermined rotational position of the cam member. A pair of engagement holes extending in the radial direction are formed so that they can communicate with each other at the same time, and the engagement holes on each cam member side are formed slightly larger in diameter than the engagement holes on the cam shaft side. In addition, a spring and a first plunger biased by the spring are slidably arranged in the engagement holes on the side of each cam member, and the engagement holes on the side of each camshaft are oil passages formed inside the camshaft. A second plunger is slidably disposed in the camshaft side engagement hole, and the second plunger is engaged with the cam member side by controlling the hydraulic pressure into the oil passage in the camshaft. hole The cam member can be locked or unlocked on the cam shaft by entering or exiting the cam member, and when the second plunger enters the cam member side engaging hole, the cam shaft side engaging member can be locked or unlocked. The dowel hole is circumferentially offset with respect to each cam member side engagement hole by a predetermined amount, and as a result, each second plunger is configured to cooperate to restrain the cam member. Engine valve drive.