JPH03117604A - Valve timing control device - Google Patents

Abstract

PURPOSE:To avoid lowering of hydraulic pressure of a hydraulic power source and increase of oil residual pressure in an oil pressure chamber by closing an oil passage communicated with the hydraulic power source when a control valve is switched to release the oil in the oil pressure chamber to a drain. CONSTITUTION:In a valve timing control device 10, at the time of returning the valve timing to the initial state, an electric current applied to a control valve 100 is switched off to release the oil in an oil pressure chamber 24 to a drain through an outlet port 113 and a drain port 115. Simultaneously the communication between an inlet port 111 and the outlet port 113 is interrupted to close an oil passage connected to an oil pump. Thus, the oil of engine hydraulic pressure generated in the oil pump can be prevented from being released to the drain port 115, so that it is possible to avoid such a problem that the engine hydraulic pressure on oil pump side is lowered. The release amount of oil in the oil pressure chamber 24 to the drain can be increased so that it is also possible to avoid such a problem that the residual pressure of oil remains in the oil pressure chamber 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve timing control device. This valve timing control device can be applied to, for example, a valve mechanism of an engine.

[Prior Art] Valve timing control device ζFor example, a valve timing control device used in an engine valve mechanism has conventionally been capable of relative displacement in the circumferential direction of the camshaft that opens and closes the valve. a timing pulley disposed in the camshaft, a piston interposed between the camshaft and the timing pulley so as to be movable in one direction and the other along the axial direction of the camshaft; Consists of a spring that biases in one direction, a hydraulic chamber that generates hydraulic pressure that biases the piston in the axial direction of the shaft and in the other direction, and a control valve that supplies part of the engine hydraulic pressure to the hydraulic chamber. It has been known. The control valve has an inlet port connected to the oil pump and an outlet port connected to the hydraulic chamber.

In the above device, when changing the valve opening/closing timing, the control valve is operated to communicate the inlet port and the outlet port, and the engine hydraulic pressure generated by the oil pump is supplied to the hydraulic chamber, and the oil supplied to the hydraulic chamber is The piston is moved against the spring, thereby displacing the camshaft relative to the timing pulley in the circumferential direction.

[Problems to be Solved by the Invention] In the above device, in order to restore the valve opening/closing timing, the drain port is opened and the oil in the hydraulic chamber is discharged to the drain, but at this time, the oil in the hydraulic chamber is discharged to the drain. The oil passage will communicate with the drain, and the oil in the oil passage leading to the oil pump will also be released into the drain. As a result, a problem arises in which the engine oil pressure (original pressure) drops significantly from its original value, and the required engine oil pressure (original pressure)
Problems arise that have an adverse effect on other lubrication systems that require lubrication.

On the other hand, in order to avoid the problem of the engine oil pressure dropping significantly from its original value, it is possible to reduce the amount of oil discharged to the drain, but in this case, oil tends to remain in the hydraulic chamber and When the residual pressure of the oil increases, and as a result, the timing of opening and closing the valve is changed again, the spring loses its strength to the residual pressure of the oil in the hydraulic chamber, so it is necessary to make the spring constant of the spring excessively large.

In addition, if the spring constant of the spring is increased excessively in this way, when hydraulic pressure is applied to the hydraulic chamber to move the piston against the spring and relatively displace the camshaft in the circumferential direction, the engine oil pressure in the low pressure region ( (low rotation range), the magnitude of the oil pressure cannot easily exceed the spring force of the spring, and as a result, the responsiveness of switching the camshaft position decreases significantly, and switching becomes impossible in the low pressure range of engine oil pressure. A problem arises.

The present invention has been developed in view of the above-mentioned circumstances, and its technical objectives are to avoid the problem of a large drop in the oil pressure of a hydraulic power source, avoid an increase in the residual pressure of oil in the hydraulic chamber, and solve the problem of a spring. It is an object of the present invention to provide a valve opening/closing timing control device that can reduce the spring constant of the means and improve switching responsiveness when relatively displacing a shaft in the circumferential direction even in a low pressure range of hydraulic pressure of a hydraulic power source.

[Means for Solving the Problems] The valve opening/closing timing control device of the present invention includes: a shaft rotatably held at a base for opening and closing the valve; disposed on the outer circumferential side of the shaft so as to be relatively displaceable in the circumferential direction of the shaft; A timing pulley that rotates the shaft is interposed between the shaft and the timing pulley so that it can move freely in one direction and the other along the axial direction of the shaft, and as it moves in one direction, it rotates the shaft and timing pulley in the circumferential direction. A piston means for relatively displacing the shaft and the timing pulley in one direction, and a spring for biasing the piston means in one direction in the axial direction of the shaft. a hydraulic chamber that generates hydraulic pressure that urges the piston means in the axial direction of the shaft and the other direction; an inlet port that is interposed between the hydraulic chamber and the hydraulic source and that is connected to the hydraulic source; and an inlet port that is connected to the hydraulic chamber. A control valve has an outlet port and a drain port connected to a drain, and the control valve has a first control position that communicates the inlet port and the outlet port to supply oil from the hydraulic pressure source to the hydraulic chamber, and a first control position that connects the outlet port to the first control position. It is characterized in that it can be switched to a second control position in which the hydraulic pressure chamber is communicated with a drain port to discharge oil from the hydraulic chamber to the drain, and the inlet port is shut off to close the oil passage connected to the hydraulic pressure source.

Further, in the device according to the second claim, the control valve communicates the inlet port and the outlet port, and in the second control position, causes the hydraulic pressure from the hydraulic source to act on the outlet port, and controls the control valve when discharging the oil in the hydraulic chamber to the drain. It has a structure with minute communication openings that suppress air inflow into the hydraulic chamber side.

[Function] When changing the valve opening/closing timing, the control valve is operated to the first control position, its inlet port and outlet port are communicated, and oil from the hydraulic source is supplied to the hydraulic chamber, and the oil in the hydraulic chamber is Move the piston against the spring. Then, the shaft is displaced relative to the timing pulley in the circumferential direction.

In addition, in order to return the valve opening/closing timing, the control valve is operated to the second control position to shut off the inlet port of the control valve and close the oil passage leading to the hydraulic pressure source, while also communicating the outlet port and the drain port to The oil in the chamber is discharged to the drain via the drain port. The shaft then relatively displaces the timing pulley in the circumferential direction and returns to its original position.

[Examples] Hereinafter, preferred embodiments embodying the technical problems of the present invention will be described based on the accompanying drawings.

(Configuration of Embodiment) FIG. 1 shows a sectional view of a valve timing control device 10 according to an embodiment in which the present invention is applied to a valve operating mechanism of an automobile engine.

A camshaft 12 serving as a shaft opens and closes a valve of a valve mechanism, and is rotatably supported by a cylinder head 11 serving as a base.

An oil passage 13 is provided inside the camshaft 12. A timing pulley 16 is fitted on the outer periphery of the camshaft 12 on the left side in the figure.
A groove 16a is formed on the outer periphery of 6 to engage with a flashing timing belt. In addition, the timing pulley 16
A damper case 15 is held at the left end of the camshaft 12 via a knock pin 14 so as to cover the camshaft 12 .

The damper case 15 and the timing pulley 16 are engaged with each other through labyrinth grooves 15a and 16b, so that a viscous damper means 17 having viscous fluid therein is engaged with the damper case 15 and the timing pulley 16.
is formed.

A cover 18 is disposed on the left side of the damper case 15 so as to cover the viscous damper means 17, and its outer peripheral portion engages with a portion of the timing pulley 16. The viscous fluid sealed within the damper means 17 is also supplied to an oil seal 19 disposed between the cover 18 and the damper case 15, an O ring 20 disposed between the cover 18 and the timing pulley 16, and an O-ring 20 disposed between the cover 18 and the timing pulley 16. An oil seal 21 disposed between the damper case 15 and the timing pulley 16 prevents the oil from flowing out.

A piston 22 serving as piston means is disposed between the inner circumference of the damper case 15 and the outer circumference of the camshaft contact portion 16c of the timing pulley 16. A spring 23 serving as a spring means for biasing the piston 22 to the left in the figure is disposed within the groove 22a of the piston 22.

A helical spline 1 is provided on the inner circumference of the damper case 15.
5b is formed, and a helical spline 22b is formed on the outer circumference of the piston 22 so as to mesh with it. Further, a helical spline 22c is formed on the inner peripheral portion of the piston 22, and a helical spline 16d is formed on the camshaft contact portion 16c of the timing pulley 16 so as to mesh with the helical spline 22c.

A hydraulic chamber 24 is formed by the inner peripheral portion of the damper case 15, the top of the piston 22, and the camshaft contact portion 16c of the timing pulley 16. This hydraulic chamber 24 communicates with the oil passage 13 within the camshaft 12.

Note that from the left side of the damper case 15 in the figure, a port 26 is screwed into the dovetail hole 12c of the camshaft 12 via a ring 25, and the camshaft 12 of the damper case 15 etc.
This prevents people from handling them.

Now, the control valve 100 is interposed between the hydraulic chamber 24 and an oil pump serving as a hydraulic pressure source. The control valve 100 is a valve 1
101, a spool valve 103 which is movably arranged in the valve chamber 101 and has a hole 103a and a center hole 103b, and a spring 104 which urges the spool valve 103 to the left in the figure. Housing 10
2, a coil 105 and an iron core 106 forming an electromagnet are arranged. The coil 105 is connected to a control circuit 107. Signals from a water temperature sensor 108, a load sensor 109, and an engine speed sensor 110 are input to the control circuit 107. causes current to flow through the coil 105.

Further, the housing 102 of the control valve 100 is formed with an inlet port 111, an outlet port 113, a drain port 115, and a communication hole 118 as a minute communication opening. The inlet port 111 is connected to an oil pump, and the engine oil pressure generated by the oil pump acts thereon. Outlet port 113
is connected to the hydraulic chamber 24 via an oil passage 116.13. Drain port 115 connects to a drain. Communication hole 1
18 communicates the inlet port 111 and the outlet port 113.

Here, when the control valve 100 is in a power-off state, the spool valve 103 is pressed by the spring force of the spring 104, moves to the left in the figure, and is set to the second control position shown in FIG. In this case, as shown in FIG.
3, the communication between the inlet port 111 and the outlet port 113 is cut off, and the drain port 115, the outlet port 113, the hole 103a of the spool valve 103, and the center hole 103
It communicates via b.

Further, when the control valve 100 is in the energized state, the coil 10
5 is energized to form an electromagnet, the spool valve 103 moves to the right in the figure against the spring force of the spring 104 and is set to the first control position. In this case, inlet port 111 and outlet port 113 are in communication.

(Operation of the embodiment) In the above configuration, when the engine starts and the crankshaft (not shown) rotates, the rotation is transmitted to the timing pulley 16 via the timing belt. The rotational torque is the timing pulley 16, the timing pulley 16
The helical spline 16d1 of the piston 22, the helical spline 22C122b1, the helical spline 15b1 of the damper case 15, is transmitted to the damper case 15, the knock pin 14, and the camshaft 12, and as a result, the valves installed on the camshaft 12 are opened and closed.

If you want to change the valve opening/closing timing of the engine's valve mechanism from such a normal driving state, for example, to bring it earlier, when power is supplied to the control valve 100, the coil 105 forms an electromagnet, and the spool valve 103 moves as shown in the right side of the figure. Stroke towards the first
control position, inlet port 111 and outlet port 113
The drain port 115 is blocked and is in a non-communicating state.

Therefore, engine hydraulic oil is supplied to the hydraulic chamber 24 through the oil passage 13 of the camshaft 12 via the inlet port 111, the outlet port 113, and the oil passage 116.
As a result, the piston 22 is slid to the right in the drawing.

This expands the volume of the hydraulic chamber 24. That is, the piston 22 overcomes the urging force of the spring 23 to the left in the drawing and moves to the right in the drawing. Then, the helical splines 15b of the damper case 15 engage with the helical splines 22b122c on the inner and outer circumferences of the piston 22, respectively.
The camshaft 12 is displaced relative to the timing pulley 16 in the circumferential direction by the helical spline 16d of the timing pulley 16, and therefore the valve opening/closing timing of the engine valve mechanism is advanced.

Further, if it is desired to restore the valve opening/closing timing of the valve mechanism of the engine (not shown) from this state, the current to the control valve 100 is turned off. Then, the spool valve 103 is returned to its original state by the spring force of the spring 104 and moved to the right in the figure to reach the second control position, so that, as is clear from FIG. 1, the oil passage leading to the oil pump is closed. ,
Communication between the inlet port 111 and the outlet port 113 is cut off, and engine oil pressure is cut off. At the same time, the outlet port 13 and the drain port 115 are communicated with each other, so that the oil in the hydraulic chamber 24 is returned to the drain through the outlet port 113, the hole 103a, the central hole 103b1, and the drain port 115. Therefore, in this embodiment, the residual pressure of the oil in the hydraulic chamber 24 also disappears, and the volume of the hydraulic chamber 24 decreases. In other words,
The piston 22 moves to the left in the drawing due to the urging force of the spring 23 to the left in the drawing. Then, the camshaft 12 is moved relative to the timing pulley 16 in the circumferential direction by the helical spline 15b of the damper case 15 and the helical spline 16d of the timing pulley 16, which engage with the helical splines 22b and 22G on the inner and outer circumferences of the piston 22, respectively. As the valve rotates, the valve opening/closing timing of the valve mechanism of the engine (not shown) is returned.

In this manner, the valve opening/closing timing of the valve mechanism can be continuously controlled by the amount of oil supplied to the hydraulic chamber 24.

In the present embodiment, the camshaft 12 receives variable torque from a spring that engages with a valve (not shown) during engine operation. This fluctuating torque is transmitted through the damper case 15 to the helical splines 15b, 22b, 22c,
16d, each helical spline 15b, 22
The backlash of b, 22c, and 16d causes a hitting sound. In this regard, in this embodiment, the camshaft 12
Because the labyrinth groove 15a formed in the damper case 15, which is integral with the damper case 15, and the labyrinth groove 16b formed in the timing pulley 16 rotate relative to each other, a large A shearing force acts, and the above-mentioned fluctuating torque can be absorbed.

In addition, when switching the valve opening/closing timing, the labyrinth groove 15
The relative rotational speed between the labyrinth groove 16a and the labyrinth groove 16b is sufficiently lower than the relative rotational speed when receiving the above-mentioned fluctuating torque. Therefore, the shearing force generated in the viscous fluid sealed in the viscous damper means 17 is small and does not interfere with switching the valve opening/closing timing.

(Effects of Example) According to this example, the control valve 100 is connected to the second
Switch to the control position and transfer the oil in the hydraulic chamber 24 to the outlet port 1.
13. When discharging into the drain via the drain port 115, communication between the inlet port 111 and the outlet port 113 is cut off, and the oil passage leading to the oil pump is closed. Therefore, it is possible to prevent the engine oil pressure (original pressure) generated by the oil pump from being discharged to the drain port 115, thereby avoiding the problem of the engine oil pressure (original pressure) on the oil pump side decreasing.

In this way, in this embodiment, even if the amount of oil discharged from the hydraulic chamber 24 to the drain is increased, a decrease in engine oil pressure can be avoided. The problem of residual oil pressure remaining in the spring 24 can also be avoided, and therefore there is no need to make the spring constant of the spring 23 excessively large. Therefore, even when the engine oil pressure is in a low oil pressure range (low rotation), switching responsiveness when relatively displacing the camshaft 12 can be improved.

Further, as described above, when the control valve 100 is switched to the second control position, the hydraulic chamber 24 communicates with the drain via the outlet port 113 and the drain port 115, so the oil in the oil passage 116.13 flows out to the drain. In this case, there is a possibility that air may flow into the oil passage 116.13. When air flows in in this way, when the control valve 100 is next switched to the first control position and oil is supplied to the hydraulic chamber 24, the increase in the oil pressure in the hydraulic chamber 24 is delayed due to the influence of the air that has flowed in. There is a possibility that the switching responsiveness of the opening/closing timing of the camshaft 12 may be reduced. In this regard, in this embodiment, inlet port 1
A thin minute communication hole 11 between 11 and the outlet port 113
8, the oil on the inlet port 111 side passes through the communication hole 118 to the outlet port 113 and the oil passage 116.
It acts on and leaks. Therefore, when the oil in the hydraulic chamber 24 is discharged to the drain, the volume of the space other than the oil in the outlet port 113 becomes smaller, and the outlet port 113 and the oil passage 1 become smaller.
It is possible to prevent air from flowing into the camshaft 16 as much as possible, thereby preventing the problem of delay in switching response of the camshaft 12.

[Other Embodiments] In the embodiments described above, the communication hole 118 is formed in the housing 102 of the control valve 100 to improve the problem of air flowing into the outlet port 113 and the oil passage 116 side. A spool gap may be formed as a minute communication opening between the outer peripheral surface of the spool valve 103 of the control valve 100 and the inner wall surface of the valve chamber 101 of the housing 102.

[Effects of the Invention] According to the valve opening/closing timing control device of the present invention, when the control valve is switched to the second control position and the oil in the hydraulic chamber is discharged to the drain, unlike conventional devices, the oil connected to the hydraulic source is This configuration closes the passage. Therefore, it is possible to avoid the problem of a large drop in the oil pressure of the oil pressure source, avoid an increase in the residual pressure of oil in the oil pressure chamber, and reduce the spring constant of the spring means to allow relative displacement of the shaft and timing pulley in the circumferential direction. It is possible to improve the switching responsiveness when

Furthermore, according to the valve timing control device of the present invention according to the second aspect, it is advantageous to avoid the inflow of air, and it is possible to prevent a decrease in switching responsiveness due to the inflow of air.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a valve timing control device shown together with a hydraulic circuit for a control valve. In the figure, 12 is a camshaft (shaft), 16 is a timing pulley, 23 is a spring (spring means), 2
2 is a piston (piston means), 24 is a hydraulic chamber, 100
is a control valve, 111 is an inlet port, 113 is an outlet port,
115 is a drain port, and 118 is a communication hole (micro communication opening).

Claims (2)

[Claims] (1) A shaft that is rotatably held at the base and opens and closes the valve; a timing pulley that is disposed on the outer circumferential side of the shaft so as to be relatively displaceable in the circumferential direction of the shaft and rotates the shaft; and the shaft and the timing pulley. is interposed between the shaft so as to be movable in one direction and the other along the axial direction of the shaft, and as the shaft and the timing pulley move in one direction, the shaft and the timing pulley are relatively displaced in one direction in the circumferential direction;
a piston means for relatively displacing the shaft and the timing pulley in the other direction in the circumferential direction as the shaft and the timing pulley move in the other direction; a spring means for biasing the piston means in one direction in the axial direction of the shaft; a hydraulic chamber that generates a hydraulic pressure that urges the means in the axial direction of the shaft and the other direction; an inlet port that is interposed between the hydraulic chamber and the hydraulic source and is connected to the hydraulic source; and an outlet that is connected to the hydraulic chamber. and a control valve having a drain port connected to a drain, the control valve having a first control position that communicates the inlet port and the outlet port and supplies oil from a hydraulic source to the hydraulic chamber. and a second control position in which the outlet port and the drain port are communicated to release the oil in the hydraulic chamber to the drain, and the inlet port is shut off to close the oil passage connected to the hydraulic source. Features: Valve opening/closing timing control device. (2) The control valve communicates the inlet port and the outlet port,
The valve according to the first claim, which has a minute communication opening that suppresses air inflow into the hydraulic chamber side when the oil pressure from the hydraulic source is applied to the outlet port in the second control position and the oil in the hydraulic chamber is discharged to the drain. Opening/closing timing control device.