JP2785304B2 - Valve timing control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a valve opening / closing timing control device, and is used for, for example, a general valve gear of an internal combustion engine.

(Prior Art) As a prior art relating to the present invention, for example,
There is a thing described in 3111 public information.

FIG. 2 shows a prior art valve timing control device 50. In this conventional technique, between a timing pulley 51 having a gear formed on an inner peripheral portion and a cam shaft 52 having a gear formed on an outer peripheral portion,
The driving force of the timing pulley 51 is transmitted to the camshaft 52 via an axially movable piston means 53 having gears formed on the inner and outer peripheral portions. Here, the cam shaft 52 is advanced to control the valve opening / closing timing by relatively rotating the timing pulley 51 and the cow shaft 52 by moving the piston means 53 in the axial direction.

When the piston means 53 receives the fluctuating torque from the camshaft 52, the piston means 53 moves between the gear part on the outer peripheral part of the piston means 53 and the gear part on the inner peripheral part of the timing pulley 51, and
A hitting sound is generated due to a backlash between the gear portion on the inner peripheral portion of the cam shaft 53 and the gear portion on the outer peripheral portion of the cam shaft 52. 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 formed into scissors, so that the gear part on the outer peripheral part of the piston means 53 and the timing pulley 51 are provided. The backlash between the gear portion on the peripheral portion and the gear portion on the inner peripheral portion of the piston means 53 and the gear portion on the outer peripheral portion of the cam shaft 52 are set to zero. Therefore, the occurrence of the hitting sound due to the backlash can be eliminated.

(Problems to be Solved by the Invention) However, in the above-mentioned prior art, in order to prevent the piston means 53 from moving in the axial direction in response to the torque fluctuation of the camshaft 52 that occurs during a steady state, the spring 54 The pressing load must be set large. Therefore, the piston means 53 when the cam shaft 52 is advanced
Operating pressure must be high. However, when the engine speed is low, the oil pump discharge pressure is low due to the engine drive.
The advance angle of 52 becomes impossible.

Therefore, in the present invention, it is an object of the present invention to reduce the pressing load of the spring holding the piston means.

Further, the backlash between the gear portion on the outer peripheral portion of the piston means 53 and the gear portion on the inner peripheral portion of the timing pulley 51 and the gap between the gear portion on the inner peripheral portion of the piston means 53 and the gear portion on the outer peripheral portion of the camshaft 52 are reduced to zero. Therefore, since the piston means 53 is formed as scissors, the forward protrusion amount (left protrusion amount in the figure) of the device itself becomes large, which is disadvantageous in mounting the valve opening / closing timing control device on the internal combustion engine.

Therefore, in the present invention, the piston means 53 is not scissorized, and the gear portion on the outer peripheral portion of the piston means 53 and the gear portion on the inner peripheral portion of the timing lift pulley 51, and the gear portion on the inner peripheral portion of the piston means 53, and the camshaft. The second purpose is to prevent the hitting sound caused by the backlash between the outer peripheral gear portion and the gear portion.
Technical issues.

[Configuration of the invention]

(Means for Solving the Problems) The technical means of the present invention taken to achieve the first and second technical problems described above includes a timing pulley rotatably supported on a camshaft, and a timing pulley. A cam is provided between the pulley and the camshaft so as to be movable in the axial direction, and is engaged with the camshaft and the timing pulley via internal teeth and external teeth formed on the inner and outer circumferences thereof. A piston means for transmitting a driving force to the shaft; and a spring means for axially urging the piston means toward an initial position, wherein at least one of the internal teeth and the external teeth of the piston means is formed in a helical shape. A valve opening / closing timing control device that relatively rotates the timing pulley and the camshaft according to the movement of the piston means; The viscous damper means is interposed between the pulley and the camshaft.

(Operation) According to the technical means described above, the viscous damper means is interposed between the timing pulley and the camshaft, so that the spring holding the piston means does not need to absorb the fluctuating torque. Since it is sufficient only to hold the spring, the pressing load of the spring can be reduced.

Further, since the fluctuating torque of the camshaft is completely absorbed by the viscous damper means, the gearshaft on the outer peripheral part of the piston means and the gear part on the inner peripheral part of the timing pulley, and the gear part on the inner peripheral part of the piston means are connected to the camshaft. Despite the backlash between the outer gear and the gear,
No rattling occurs between the gear portions, so that no hitting sound is generated.

(Embodiments) Preferred embodiments embodying the technical problems of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a valve timing control apparatus 10 according to an embodiment of the present invention.

The camshaft 12 is rotatably supported by the engine body 11. An oil passage 13 is provided inside the camshaft 12. A timing pulley 16 is fitted on the left outer peripheral portion of the camshaft 12 in the drawing,
The outer periphery of the groove 16 has a groove 16a. Further, a damper case 15 is disposed at the left end of the cam shaft 12 in the drawing via a notch pin 14 so as to cover the timing pulley 16. The damper case 15 and the timing pulley 16 are engaged by respective labyrinth grooves 15a and 16b, thereby forming a viscous damper means 17 having a viscous fluid therein.

A viscous damper means is provided on the left side of the damper case 15 in the drawing.
A cover 18 is provided so as to cover 17, and its outer peripheral portion is engaged with a part of the timing pulley 16. The viscous fluid sealed in the viscous damper means 17 is
Oil seal 1 disposed between the
9, O-ring 20 disposed between cover 18 and timing pulley 16, and damper case 15 and timing pulley
The outflow is prevented by an oil seal 21 disposed between the oil seal 16 and the oil seal 16.

A piston means 22 having a cylindrical groove 22a is disposed between the inner peripheral part of the damper case 15 and the outer peripheral part of the cam shaft contact part 16c of the timing pulley 16, and the piston means 22 is provided in the groove 22a. Spring 23 biased to the left as shown
Are arranged.

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

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

A ring 25 and a bolt 26 are screwed into the camshaft 12 from the left side of the damper case 15 in the drawing.
And the like from the camshaft 12 are prevented.

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, and the helical splines 22c, 22 of the piston means 22.
b, the helical spline 15b of the damper case 15, the damper case 15, the knock pin 14, and the camshaft 12 are transmitted.

If it is desired to advance the valve opening / closing timing of an engine (not shown) from the state of the normal running, oil is supplied to the oil passage 13 to increase the capacity of the hydraulic chamber 24. That is, the piston means 22 moves to the right in the figure overcoming the biasing force of the spring means 32 to the left in the figure. Then, the camshaft 12 integrated with the damper case 15 is formed by the helical splines 15b of the damper case 15 and the helical splines 16d of the timing pulley 16 which engage with the helical splines 22b and 22c on the inner and outer circumferences of the piston means 22, respectively. By rotating relative to the timing pulley 16, the valve opening / closing timing of an engine (not shown) is advanced.

When 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. That is, the piston means 22 moves to the left in the figure by the urging force of the spring means 23 to the left in the figure. Then, the camshaft 12 integrated with the damper case 15 is formed by the helical splines 15b of the damper case 15 and the helical splines 16d of the timing pulley 16 which engage with the helical splines 22b and 22c on the inner and outer circumferences of the piston means 22, respectively. By rotating relative to the timing pulley 16, the valve opening / closing timing of the engine (not shown) is returned.

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

The camshaft 12 receives a fluctuating torque from a spring engaged with a valve (not shown) during operation of the engine. This fluctuating torque is transmitted to the helical splines 15b, 22b, 22c, and 16d via the damper case 15, and generates a tapping sound by the backlash of each helical spline 15b, 22b, 22c, and 26d, and a negative component of the fluctuating torque. Is the piston means
22 is to be moved rightward in the figure. Then, since the labyrinth groove 15a formed in the damper case 15 integrated with the camshaft 12 and the labyrinth groove 16b formed in the timing pulley 16 rotate relatively, the viscous fluid (for example, silicon) sealed in the viscous damper means 17 is used. oil)
Thus, a greater shearing force acts to absorb the fluctuating torque.

However, when switching the valve timing, the camshaft
The relative rotation speed of the labyrinth groove 15a formed in the damper case 15 and the labyrinth groove 16b formed in the timing pulley 16 is sufficiently lower than the relative rotation speed when receiving the fluctuating torque. Therefore, the shear force generated in the viscous fluid sealed by the viscous damper means 17 is small, and does not hinder the switching of the valve opening / closing timing.

〔The invention's effect〕

According to the present invention, since the viscous damper is interposed between the timing pulley and the camshaft, the fluctuation torque of the camshaft can be absorbed without increasing the size of the valve opening / closing control device. Therefore, between the gear portion of the outer peripheral portion of the piston means and the gear portion of the inner peripheral portion of the timing pulley,
And, despite the backlash between the gear portion on the inner peripheral portion of the piston means and the gear portion on the outer peripheral portion of the camshaft, no rattling occurs between the gear portions, so that no hitting sound is generated.

In addition, since the viscous damper means is interposed between the timing pulley and the camshaft, the pressing load of the spring means holding the piston means is reduced, so that the valve opens and closes even in a low rotation range, that is, in a region where the supply hydraulic pressure is low. The timing can be switched, and a valve opening / closing control device having excellent responsiveness can be configured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a valve timing control apparatus according to an embodiment of the present invention. FIG. 2 shows a sectional view of a prior art valve timing control apparatus. 10: Valve opening / closing timing control device, 12: Camshaft, 15: Damper case, 16: Timing pulley, 17: Viscous damper means, 22: Piston means, 23: Spring means.

Claims (1)

(57) [Claims] A timing pulley rotatably supported on a camshaft, and internal and external teeth formed on the inner and outer circumferences of the timing pulley and the camshaft are provided so as to be movable in the axial direction. Piston means engaged with the camshaft and the timing pulley to transmit driving force from the timing pulley to the camshaft, and spring means for urging the piston means in an axial direction toward an initial position; Wherein at least one of the internal teeth and the external teeth of the piston means is formed in a helical shape, and the valve opening / closing timing control device for relatively rotating the timing pulley and the camshaft according to the movement of the piston means, A valve opening / closing timing control device comprising a viscous damper means interposed between a timing pulley and said camshaft. .