JPS60135611A - Suction/exhaust valve gear of internal-combustion engine - Google Patents

Abstract

PURPOSE:To contrive to miniaturize a hydraulic actuator by a structure wherein a stopper to a lever is provided in order to control the inclination angle of the lever, which comprises the fulcrum of a rocker arm by supporting the back surface of the rocker arm, by means of the pressure oil of the actuator. CONSTITUTION:The fulcrum of a rocker arm 17 consists in supporting the back surface of the arm 17 by a lever 20, the one end 20a of which is supported by the tip 24 of a bracket 14 and the other end 24b of which is supported by a hydraulic actuator 25. The degree of extensibility of the actuator 25 is controlled in proportion to the pressure of oil supplied to the actuator 25 in order to obtain a valve lift suitable for the running conditions of an engine. During high speed running, the actuator 25 extends and consequently pressure oil is supplied from an oil gallery 26 through a groove 39 into a hydraulic pressure chamber 38, resulting in shifting a stopper 34 so as to bear the back surface of the lever 20. Thus, the large load applied during high speed running is borne by the stopper 34 and consequently the actuator 25 is miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an intake/exhaust valve drive device for an internal combustion engine that variably controls the opening/closing timing of intake/exhaust valves and the valve lift according to operating conditions.

(b) Conventional technology An intake and exhaust valve drive device that variably controls the opening/closing timing of the intake and exhaust valves and the valve lift can according to engine operating conditions so that valve overlap, fresh air charging efficiency, etc. can always be optimally obtained. Various proposals have been made in the past, one of which is known as US Pat. No. 3,413,965 shown in FIG.

This valve drive device has one end in contact with the valve drive cam 1,
In addition, the back surface 4 of the rocker arm 3 whose other end is fitted and supported by the stem end of the intake/exhaust valve 2 is formed into a curved shape, and the rocker arm 3 swings while the back surface 4 contacts the lever 5 as a fulcrum, so that the cam 1 is rotated. Lift is transmitted to the intake and exhaust valves 2, and in particular, the lever 5 is pivotably supported at one end thereof, and its inclination is regulated by a control cam 6. The control cam 6 is rotationally driven in an appropriate phase according to engine operating conditions by a drive mechanism such as a hydraulic actuator, thereby variably controlling the opening/closing timing and lift amount of the intake/exhaust valve 2. That is, for example, if the lever 5 is pushed down by the control cam 6 to a large extent, the free end of the lever 5 and the rocker arm 3 are
are close to each other, therefore, the opening timing of the intake and exhaust valves 2 is advanced, the valve lift amount is large, and the control cam 6 is
If the amount of depression is small, the same valve drive cam 1
Even in the base circle state, the free end of the lever 5 and the rocker arm 3 are separated from each other, so that the opening timing of the intake and exhaust valves is delayed and the amount of valve lift is small.

However, in such a conventional valve drive device, when applied to a multi-cylinder engine with four or more cylinders, for example, one of the intake and exhaust valves 2 is always lifted. A large torque acts on the shaft 6a of the control cam 6 due to the reaction force, and in order to resist this force and rotate the shaft 6a, a large and powerful actuator is required. Therefore, for example, in an automobile engine, it is difficult to arrange a large actuator within a limited space, and on the other hand, there is also a problem in terms of responsiveness of control of the control cam 6. Moreover, power loss and wear on the cam surface caused by driving the control cam 6 become large.

In order to improve these problems, the present applicant has previously filed an application for an intake and exhaust valve drive device for an internal combustion engine, which is configured to individually control the inclination of levers using actuators that expand and contract according to hydraulic pressure. (Special application 1982)
-142387).

(c) Purpose of the Invention The present invention is a further improvement of the above-mentioned intake and exhaust valve drive device for an internal combustion engine, and aims to provide an intake and exhaust valve drive device for an internal combustion engine that also improves the inconveniences caused when controlling by hydraulic pressure. purpose.

(d) Structure of the Invention In order to achieve the above object, the present invention includes: a valve drive cam that rotates in synchronization with an engine; a rocker arm that has one end abutting the valve drive cam and the other end connected to a valve stem; A lever that is disposed approximately along the back surface of the rocker arm and has a support surface with which the back surface makes fulcrum contact; a bracket that supports one end of the lever on the valve side; and a bracket that supports one end of the lever on the cam side and operates. An actuator that controls the inclination of the lever by expanding and contracting in response to hydraulic pressure, and a stopper device that operates to solidly support the cam side of the lever at a predetermined inclination position of the lever are provided.

(E) Examples Hereinafter, specific examples of the present invention will be described in detail based on the drawings.

FIG. 2 is a sectional view showing a first embodiment of the invention,
11 is a valve drive cam that rotates in synchronization with engine rotation;
2 is an intake/exhaust valve, 13 is a valve spring, and 14 is a bracket fixed to the cylinder head 15 with a bolt 16''.
1, a rocker arm whose other end 17b abuts each stem end 12b of the valve stem 12a, has a support shaft 18 rotatably inserted through the approximate center, and whose back surface 19 is curved to a predetermined profile. , 20 are arranged substantially along the back surface 19 of the rocker arm 17, and the back surface 1
This lever 2O is equipped with a rocker arm support surface 21 that is in fulcrum contact with the lever 2O.
A support shaft 18 of the rocker arm 17 is slidably fitted into the support shaft 18 of the rocker arm 17, and a coil spring 23 is provided between the support shaft 18 and the lever 20 for biasing the lever 20 toward the bracket 14. Compressed arrangement. Also"
- The lever 20 has one end 20a on the valve side (A) in contact with and supported by an adjustment screw 24 on the tip edge of the bracket 14, and one end 20b on the cam side is supported by an actuator 25 embedded in the bracket 14. The inclination of the lever 20 is controlled by the expansion and contraction of the actuator 25.

The actuator 25 has a total length that expands and contracts depending on the control hydraulic pressure as a working hydraulic pressure introduced from an oil gear rally 26 in the bracket 14 in accordance with the engine operating conditions.
It has a bottomed cylindrical outer cylindrical part 28 that is slidably fitted into the inner part 7 .

This outer cylinder part 28 has an inner part 3 having an oil reservoir chamber 29 therein.
0 is slidably fitted, and the oil reservoir chamber 29 is communicated with the oil gear gallery 26 through the hole 28a of the outer cylinder part 28 and the hole 30a of the inner cylinder part 30. A coil spring 31 is interposed between the outer cylinder part 28 and the inner cylinder part 30 to urge the outer cylinder part 28 in the projecting direction, and a hydraulic chamber 32 is defined.
A hydraulic chamber 32 communicates with the oil reservoir chamber 29 via a check valve 33. A hemispherical pivot portion 28b is formed at the top of the outer cylinder portion 28, and this pivot portion 28b is fitted into one end 20b of the lever 20.

On the other hand, a stopper device 34 is provided around the outer cylindrical portion 28 as an example of the main components of the present invention.

This stopper device 34 operates to solidly support the cam side of the lever 20 at a predetermined inclined position, and includes a stopper member 35, a return spring 36, a sleeve 37, a pressure chamber 38, and a hydraulic pressure supply groove 39. There is. The arc of the sleeve 37 is fixed to the lower surface of the bracket 14 and slidably guides the outer section 28. The pressure chamber 38 is defined by a stopper member 35 slidably fitted into a lateral sliding hole 37a formed in the sleeve 37. The stopper member 35 is formed with an inclined surface 35a that allows the stopper member 35 to smoothly ride onto the lever 2O. The return spring 36 urges the stopper member 35 to a non-operating position and is interposed between the stopper member 35 and the bracket 14. The hydraulic pressure supply groove 39 is formed in the outer cylinder part 28 and connects the hole 28a of the outer cylinder part 28 and the pressure chamber 38.
enable communication between

As shown in FIG. 3, the oil gear rally 26 is supplied with an I.
By releasing a portion of the warm lubricating oil through an electromagnetic relief valve 43, the oil pressure in A is controlled. The electromagnetic relief valve 43 is controlled by the signal, and a control oil pressure corresponding to the engine operating conditions is applied.

Next, its effect will be explained.

First, when the control oil pressure supplied from the oil gear rally 26 to the actuator 25 is low when the engine rotates at a low speed, the biasing force of the coil spring 23 causes the actuator 25 to
The overall length of the lever 20 is shortened, and the lever 20, whose one end 20a is supported by the adjustment screw 24, swings relatively upward.
When the valve drive cam 11 is in its base circle, the back surface 19 of the rocker arm 17 and the rocker arm support surface 21 of the lever 20 are in a spaced apart state. Therefore, when the valve drive cam 11 starts to lift from this state, the valve opening timing is changed to the valve drive cam 11 as shown in FIG.
The valve opening timing is delayed by a certain period from the rise of the valve drive cam 11, and similarly, the valve opening timing is a certain period earlier than the fall of the valve drive cam 11, and the maximum lift amount obtained at the peak lift of the valve drive cam 11 is also small. At this time, the oil pressure supply groove 39 is not communicating with the pressure chamber 38, and since oil is not being supplied into the pressure chamber 38, the stopper member 35 enters into the sliding hole 37a due to the bias of the return spring 36. It is located away from lever 2O.

Therefore, the lever 2O is not solidly supported by the stopper member 35, and its inclination is controlled according to the expansion and contraction of the actuator 25.

Here, as the arm 17 moves to the stop 71, a rotational force acts on the lever 2O in the clockwise direction in the drawing, but in the actuator 25, the hydraulic pressure in the hydraulic chamber 32 is maintained by the action of the check valve 33. Therefore, actuator 25
The overall length of the lever 2O remains almost unchanged, and the inclination of the lever 2O remains unchanged.

Next, when the period of high speed rotation occurs and the control oil pressure supplied to the actuator 25 increases, the rocker arm 17 is in contact with the base lever of the valve drive cam 11 during the period in which the reaction force of the valve spring 13 does not act on the lever 2O. During the period, the control oil pressure and the coil spring 31
The outer cylindrical portion 28 protrudes to the point where the angle . Therefore, the lever 2O swings counterclockwise, and the back surface 19 of the rocker arm 1-17 and the rocker arm support surface 21 of the lever 20 become close to each other. The protrusion of the outer cylinder part 28 is caused by the hole 2 of the outer cylinder part 28.
8a and the hole 30a of the inner cylindrical portion 3O is continued until the communication is interrupted as shown in FIG.

When the communication between these holes 28a and 30a is cut off, the pressure chamber 38 of the stopper device 34 is communicated with the hole 30a of the outer cylinder part 28 via the oil pressure supply groove 39, and the high control oil pressure is supplied from the oil gear gallery 26 to the pressure chamber 38. is supplied. By supplying this oil pressure, the stopper member 35 is projected from the sliding hole 37a against the return spring 36 and inserted between the lever 2O and the bracket 14. At this time, the inclined surface 35a of the stopper member 35 serves as a guide, and the stopper member 3
5 operates smoothly. The cam side of the lever 20 is solidly supported by the stopper member 35, and the supporting rigidity of the lever 20 with respect to the bracket 14 when the engine rotates at high speed is improved. Therefore, the engine rotates at high speed and the rocker arm 1
Even if the inertial force of the actuator 7 etc. increases synergistically, the actuator 25 will not be crushed by the increased inertial force, and the valve will not jump. On the other hand, intake and exhaust valve 1
2 is a valve drive cam 11 as shown in FIG. 4(b).
It opens and closes at approximately the same timing as the rise and fall of .

When the engine rotates at a low speed again, the oil pressure in the pressure chamber 38 decreases, and the stopper member 35 is slid into the slide hole 37a and removed from the lever 20 by the bias of the return spring 36. Therefore, the tilt control of the lever 2O is performed again by the expansion and contraction of the actuator 25.

In addition, in the actuator 25, every time the valve drive cam 11 is lifted, some oil in the hydraulic chamber 32 leaks from the gap with the cylinder barrel 27, etc., and at the end of the lift, the oil leaks from the oil reservoir chamber 29 to the hydraulic chamber 32. Since the necessary amount of oil is replenished, the total length can always be obtained in accordance with the control oil pressure.

According to the configuration in which the actuator 25 is used for each lever 2O as described above, the inclination of the lever 2O can be quickly controlled during the period when the reaction force of the valve spring 13 does not act, so that the actuator 25 has the necessary drive force. The force is extremely small, there is no need to provide a large and powerful hydraulic system unlike in the past, power loss can be significantly reduced, and the response f1 of the lever 20 to changes in the control oil pressure is also good. In addition, unlike the conventional lever 2
There is also no risk of premature wear. Moreover, when the engine rotates at high speed, the lever 20 is solidly supported by the operation of the stopper device 34, and the supporting rigidity of the lever 20 with respect to the bracket 1=1 can be improved, so that the intake and exhaust valves 12 jump due to an increase in inertia force. can be prevented.

The valve clearance required to cope with thermal expansion of the valve stem 12a can be adjusted very easily by moving the adjustment screw 24, which supports one end of the lever 2O, back and forth.

5 and 6 show a second embodiment of the present invention, in which the levers 20 for each valve 12 of each cylinder are simultaneously solidly supported by one shaft 51 of the stopper device 34, and the shaft 5
1 has four parts 51 that escape the contact of the lever 2O for each valve 12.
a is formed.

The shaft 51 is driven in the axial direction by a cylinder device 52 that expands when the engine rotates at high speed.

FIG. 7 shows another example of the shaft 51 in the second embodiment, and includes a fail-safe lock portion 51b that can solidly support the lever 2O in the normal use state even when hydraulic pressure is no longer applied to the actuator 25 due to a failure. .

8 and 9 show a third embodiment of the present invention, in which a control rack 62 rotates a rotating sleeve 61 interposed between the bracket 14 and the outer cylindrical portion 28 in accordance with the engine rotation speed. The stopper member 35 of the stopper device 34 is integrally constructed.

Note that an oblique slit 61a is formed in the rotating sleeve 61, and when the inclined lower side of the slit 61a faces the hole 28a of the outer cylinder part 28 due to the rotation of the control rack 62, the outer part 28 is further expanded. It has become. The control latch 62 is driven by simultaneously operating the rotary sleeves 61 of each cylinder, and is driven back and forth by an appropriate actuator 63 such as a linear motor or hydraulic cylinder installed at one end, and the amount of movement is controlled by a potentiometer. It is detected by a displacement detector 64 such as , etc., and feedback control is performed to a target value.

That is, based on various data 65 such as suction negative pressure, engine speed, and cooling water temperature, a control target signal corresponding to engine operating conditions is outputted by an arithmetic circuit 66 and a control value determination output conversion circuit 67. 68, this control target signal is compared with the detection signal from the displacement detector 64 via the converter 69, and a signal corresponding to the deviation between the two is outputted from the deviation detection circuit 70. The actuator 63 is driven by this deviation signal via the output circuit 71, and the forward/backward position of the control rack 62 is controlled to a position corresponding to the engine operating conditions.

FIG. 10 shows a fail-safe lock portion 62a similar to FIG.
6 shows a control rack 62 having a.

In the second and third embodiments, the same components as those in the first embodiment are indicated by the same reference numerals, and the explanation thereof will be omitted.

(F) Effects of the Invention As explained in detail above, according to the present invention, the inclination position of the lever can be controlled for each valve by using the rest period when the intake and exhaust valves are not lifted. , the control driving force is small, there is no need to use a large actuator, power loss and wear of levers, etc. can be reduced, and transient response of control is improved. Furthermore, the inconvenience caused by hydraulic pressure control can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional intake/exhaust valve drive device, and FIG. 2 is a sectional view of an intake/exhaust valve drive device according to a first embodiment of the present invention.
Fig. 3 is a hydraulic circuit diagram showing an example of a control hydraulic system, Fig. 4 is a lift characteristic diagram showing an example of valve lift characteristics, and Fig. 5 is a cross section of an intake/exhaust valve drive device according to a second embodiment of the present invention. 6 is a hydraulic circuit diagram, FIG. 7 is an explanatory diagram showing another example of the shaft member, FIG. 8 is a sectional view of an intake and exhaust valve drive device according to a third embodiment of the present invention, and FIG. 9 10 is a block diagram showing a control circuit of the control rack, and FIG. 10 is an explanatory diagram showing an example of the control rack. 11... Valve driving force 18 12... Intake and exhaust valve 14... Bracket 17...
Rocker arm 2O... Lever 23... Fill spring 25... Actuator 34... Stopper device Fig. 1 Fig. 2 Fig. 3 Crank angle

Claims (1)

[Claims] A valve drive cam that rotates in synchronization with the engine, a rocker arm that has one end in contact with the valve drive cam and the other end that is connected to the valve stem, and a rocker arm that is disposed approximately along the back surface of the rocker arm, with the back surface contacting the fulcrum. A lever that has a support surface that supports the lever includes a bracket that supports one end of the lever on the valve side, and an actuator that supports one end of the lever on the cam side and controls the inclination of the lever by expanding and contracting in response to hydraulic pressure. (2) An intake/exhaust valve drive device for an internal combustion engine, comprising a stopper device that operates to solidly support the cam side of the lever at a predetermined inclined position of the lever.