JPH02241914A - Valve opening and closing timing control device - Google Patents

Abstract

PURPOSE:To decrease the pressing load of a spring which holds a piston means by using a viscous damper means in a variable torque absorbing mechanism. CONSTITUTION:A cam shaft 12 is exerted with variable torque from a spring engaged with a valve during engine operation. This variable torque is transmitted to helical springs 15b, 22b, 22c, 16d through a damper casing 15, and accordingly, a negative component of the variable torque tends to move a piston means 22 rightward. Then, labyrinth grooves 15a formed in a damper casing 15 which is integrally incorporated with the cam shaft 12, and labyrinth grooves 16b formed in a timing pulley 16 are rotated, relative to each other, and accordingly, a larger shearing force is exerted to viscous fluid enclosed in a viscous damper 17 so that the variable torque may be absorbed. With this arrangement, a pressing load of a spring means 23 which holds the piston means 22 may be reduced, thereby it is possible to change over the valve opening and closing timing even in a low oil supply pressure range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a valve timing control device, and is used, for example, in general valve operating devices of internal combustion engines.

(Prior art) As the prior art related to the present invention, for example,
There is one described in Publication No. 3111.

FIG. 2 shows a conventional valve timing control device 50. As shown in FIG. In this prior art, an axially movable piston means having gears formed on the inner and outer peripheries is provided between a timing pulley 51 having gears formed on the inner periphery and a camshaft 52 having gears forming the outer periphery. 53, the timing pulley 51
The driving force is transmitted to the camshaft 52. Here, the timing pulley 51 and the camshaft 52 are rotated relative to each other by moving the piston means 53 in the axial direction, thereby advancing the camshaft 52 and controlling the valve opening/closing timing.

Further, when the piston means 53 receives a fluctuating torque from the camshaft 52, the gear portion on the outer circumference of the piston means 53 and the gear portion on the inner circumference of the timing pulley 51 and between the gear portion on the inner circumference of the piston means 53 and the gear portion on the inner circumference of the timing pulley 51. The backlash between the outer circumferential portion of the camshaft 52 and the gear portion generates a hitting sound.

Therefore, in this prior art, the piston means 53 is divided into two parts and the spring 55 is disposed between them, that is, the piston means 53 is made into a scissors.
The backlash between the gear part on the outer periphery and the gear part on the inner periphery of the timing pulley 51, and between the gear part on the inner periphery of the piston means 53 and the gear part on the outer periphery of the camshaft 52 is made zero. Therefore, the occurrence of hitting sounds due to backlash could be eliminated.

(Problem H to be Solved by the Invention) However, in the prior art described above, in order to prevent the piston means 53 from moving in the axial direction in response to torque fluctuations of the camshaft 52 that occur during steady state, The pressing load of the spring 54 must be set large. Therefore, the working oil pressure of the piston means 53 must be high when the camshaft 52 is advanced. However, at low rotations, the discharge pressure of the oil pump driven by the engine is low, so the oil pressure supplied to the valve timing control device is low, making it impossible to advance the camshaft 52.

Therefore, the technical object of the present invention is to reduce the pressing load of the spring that holds the piston means.

Also, between the gear part on the outer circumference of the piston means 53 and the gear part on the inner circumference of the timing pulley 51,
In order to eliminate backlash between the gear part on the inner circumference and the gear part on the outer circumference of the camshaft 52, the piston means 5
3 is in the form of a scissor, the amount of forward protrusion of the device itself (the amount of protrusion to the left in the figure) becomes large, which is disadvantageous when mounting the valve timing control device on an internal combustion engine.

Therefore, in the present invention, without converting the piston means 53 into a scissor, the gear part on the outer circumference of the piston means 53 and the gear part on the inner circumference of the timing hub 51, and between the gear part on the inner circumference of the piston means 53 and the camshaft 52. To prevent hammering noise due to backlash between the gear and the outer peripheral gear,
This is the second technical issue.

[Structure of the invention]

(Means for Solving the Problems) The technical means of the present invention taken to achieve the above-mentioned first and second technical problems is to use a viscous damper means as a fluctuating torque absorption mechanism. .

(Operation) According to the above-mentioned technical means, by using the viscous damper means as a mechanism for absorbing fluctuating torque, the spring that holds the piston means does not need to absorb the fluctuating torque, and can simply hold the piston means. This makes it possible to reduce the pressing load of the spring.

In addition, since the fluctuating torque of the camshaft is completely absorbed by the viscous damper means, there is a problem between the gear part on the outer periphery of the piston means and the gear part on the inner periphery of the timing pulley, and between the gear part on the inner periphery of the piston means. Even though there is backlash between the camshaft and the gears on the outer periphery, there is no play between the gears, so no hitting noise is generated.

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

FIG. 1 shows a sectional view of a valve timing control device IO according to an embodiment of the present invention.

The camshaft 12 is rotatably supported by the engine body 11. An internal oil passage 13 of the camshaft 12 is provided. A timing pulley 16 is fitted on the outer periphery of the cam shirt 1-12 on the left side in the figure, and the outer periphery of the timing pulley 16 has a groove 16a. Further, a damper case 15 is disposed at the left end of the camshaft 12 in the figure via a knock pin 14 so as to cover the timing boob I716. The damper case 15 and the timing boo 1J16 are located in their respective labyrinths 115.
a and 16b, thereby forming a viscous damper means 17 having a viscous fluid inside.

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 part of the timing pulley 16. Furthermore, the viscous fluid sealed within the viscous damper means 17 is
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 the damper case 1.
An oil seal 21 disposed between the timing pulley 16 and the timing pulley 16 prevents the oil from flowing out.

Inner circumference of damper case 15 and timing pulley 160
A cylindrical piston means 22 having a groove 22a is disposed between the outer circumference of the camshaft contact portion L6c, and a spring 23 for biasing the piston means 22 to the left in the figure is disposed within the groove 22a. has been done.

A helical spline 1 is provided on the inner circumference of the damper case 15.
5b is formed, and the piston means 2 is formed so as to mesh therewith.
A helical spline 22b is formed on the outer periphery of the helical spline 22b. Further, a helical spline 22c is formed on the inner circumference of the piston means 22, and a helical spline 16d is formed on the inner circumference of the camshaft contact portion 16c of the timing pulley 16 so as to mesh with the helical spline 22c.

The inner peripheral part of the damper case 15, the top of the piston means 22, and the camshaft contact part 16c of the timing pulley 16
A hydraulic chamber 24 is formed with the inner circumferential portion of the hydraulic pressure chamber 24. This hydraulic chamber 2
4 communicates with an oil passage 13 within the camshaft 12.

A ring 25 and a bolt 26 are screwed onto the camshaft 12 from the left side of the damper case 15 in the figure to prevent the damper case 15 and the like from coming off the camshaft 12.

In the above configuration, when the engine starts and the crankshaft (not shown) rotates, the rotation is transmitted to the timing pulley 16. During normal running, the rotational torque is applied to the timing pulley 16, the helical spline 16d of the timing pulley 16, the helical splines 22c and 22b of the piston means 22, the helical spline 15b of the damper case 15, the damper case 15, the knock pin 14,
It is transmitted to the camshaft 12.

If it is desired to advance the valve opening/closing timing of the engine (not shown) from this normal running state, oil is supplied to the oil passage 13 to expand the volume of the hydraulic chamber 24. That is, the piston means 22 overcomes the urging force of the spring means 23 to the left in the drawing and moves to the right in the drawing. Then, the helical spline 15b of the damper case 15 and the helical spline 1 of the timing pulley 16 engage with the helical splines 22b and 22c on the inner and outer circumferences of the piston means 22, respectively.
6d, the camshaft 12 integrated with the damper case 15 rotates relative to the timing pulley 16 to advance the valve opening/closing timing of the engine (not shown).

Moreover, if it is desired to return the valve opening/closing timing of the engine (not shown) from this state, the supply of oil to the oil passage 13 is stopped and the volume of the hydraulic chamber 24 is reduced. In other words, the piston means 22 moves to the left in the drawing due to the urging force of the spring means 23 to the left in the drawing. Then, the helical spline 15b of the damper case 15 and the helical spline 1 of the timing pulley 16 engage with the helical splines 22b and 22c on the inner and outer circumferences of the piston means 22, respectively.
6d, the camshaft 12 integrated with the damper case 15 rotates relative to the timing pulley 16, thereby returning the valve opening/closing timing of the engine (not shown).

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

The camshaft 12 also receives varying 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 and 22b.

22c, 16d, each helical spline 15
The backlash of the pistons b, 22b, 22c, and 16d causes a hitting sound, and the negative component of this fluctuating torque tends to move the piston means 22 to the right in the figure. Then,
Because the labyrinth groove 15a formed in the damper case 15, which is integral with the camshaft 12, and the labyrinth groove 16b formed in the timing pulley 16 rotate relative to each other,
A large shearing force acts on the viscous fluid (for example, silicone oil) sealed in the viscous damper means 17, making it possible to absorb fluctuating torque.

However, when switching the valve opening/closing timing, the camshaft 1
The relative rotational speed between the labyrinth groove 15a formed in the damper case 15 and the labyrinth groove 16b formed in the timing pulley 16, which are integral with the damper case 2, is sufficiently lower than the relative rotational speed when receiving 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.

[Effect of Gyomei]

According to the present invention, by using the viscous damper means as the fluctuating torque absorption mechanism, the fluctuating torque of the camshaft can be absorbed without increasing the size of the valve opening/closing control device. Therefore, despite the backlash between the gear part on the outer circumference of the piston means and the gear part on the inner circumference of the timing pulley, and between the gear part on the inner circumference of the piston means and the gear part on the outer circumference of the camshaft. First, there is no play between the gear parts, so no hammering sounds are generated.

In addition, by using a viscous damper means for the fluctuating torque absorption mechanism, the pressing load of the spring means holding the piston means is reduced, so switching of the valve opening/closing timing is possible even in the low rotation range where the supply oil pressure is low. This makes it possible to construct a valve opening/closing control device with excellent responsiveness.

[Brief explanation of drawings]

FIG. 1 shows a sectional view of a valve timing control device according to an embodiment of the present invention. FIG. 2 shows a sectional view of a conventional valve timing control device. Valve timing control device, camshaft, damper case, timing pulley, viscous damper means, piston means, spring means.

Claims (1)

[Claims] A valve opening/closing valve having a timing pulley, a piston means for transmitting driving force from the timing pulley to a camshaft via a damper case, a spring means for biasing the piston means to an initial position, and a fluctuating torque absorption mechanism. A valve opening/closing timing control device in which a viscous damper means is used as the fluctuating torque absorption mechanism.