JP2758890B2 - Valve timing control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake engine for an internal combustion engine.
The present invention relates to an improvement of a valve timing control device that variably controls an opening and closing timing of an exhaust valve according to an operation state.

[0002]

2. Description of the Related Art A valve timing control device of this type is disclosed, for example, in Japanese Patent Application Laid-Open No. 61-27 filed by the present applicant.
There is one described in JP-A-9713.

[0003] In this device, at least one of teeth provided on the inner and outer circumferences is provided between a timing pulley transmitted from a crankshaft of an engine and a camshaft transmitted from the timing pulley. A cylindrical gear which is a helical tooth is interposed while being meshed with the internal teeth of the timing pulley and the external teeth of the camshaft, and the cylindrical gear is driven by a driving mechanism according to an engine operating state. By moving in the axial direction, the relative rotation between the timing pulley and the camshaft is obtained, and the opening / closing timing of the intake / exhaust valves is controlled to advance / delay.

[0004] The cylindrical gear is cut into two parts by cutting from a substantially center in a direction perpendicular to the axis, and has two front and rear gears each having external teeth and internal teeth of the same tooth shape formed on the helical teeth. It has a part. The two gear components are connected movably in a direction away from or approaching to each other by a connection pin inserted in the internal axial direction across the two, and the front gear component and the connection pin head are connected to each other. It is urged in the direction approaching each other by the coil spring that is mounted between them,
It is elastically connected.

[0005] By the elastic coupling action of the two gear components, when each gear component moves in the axial direction,
By increasing the apparent tooth thickness of these internal and external teeth, shifting the tooth streaks and pressing the tooth side surfaces of the internal and external teeth against the tooth side surfaces of the inner teeth and the outer teeth, the inner and outer surfaces of the timing pulley and the camshaft are changed. It is possible to sufficiently reduce the backlash during the meshing movement with the teeth. Thus, it is possible to sufficiently suppress the occurrence of a tapping sound due to a collision between the teeth due to a fluctuation in the forward / reverse rotation torque of the camshaft caused by the spring reaction force of the valve spring.

[0006]

However, in the conventional valve timing control device, the engine shifts from a low load range to a high load range, and, for example, a pressure chamber in a front end side of a front gear component portion. When the front gear component is moved rearward by the hydraulic pressure, the rear gear component is simultaneously pushed backward by the rear end face of the front gear component, and moves rearward in a state where the two are always close to each other. That is, the two gear components move rearward while always approaching each other due to the strong combined force of the spring force of the coil spring and the oil pressure in the pressure chamber. For this reason, the pressure contact force of each external tooth of the two gear components with respect to the inner tooth and the pressure contact force of each internal tooth with respect to the outer tooth are further increased, so that the sliding friction resistance between each tooth is increased. As a result, the rearward movement speed of the entire cylindrical gear decreases, the phase conversion speed of the relative rotation between the timing pulley and the camshaft becomes slow, and the responsiveness of the valve timing control deteriorates.

In addition, the operating state of the engine shifts from a high load region to a low load region, and the entire cylindrical gear is moved forward while the front gear component is pushed back by the rear gear component by the spring force of the compression spring of the drive mechanism. A similar problem is caused when moving.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. In particular, a pressure receiving piston is slidable in the axial direction of a camshaft between a rotating body and a camshaft. And one of the gear components on the pressure receiving piston side is slidably connected in the axial direction to a support pin fixed to the pressure receiving piston in the axial direction.

According to the present invention having the above-described structure, when a hydraulic pressure is supplied to a pressure chamber provided at the front end side of the front-side gear forming section, for example, with a change in the engine operating state, the hydraulic pressure is applied to each gear-forming section, the rotating body and It acts on one end face of the pressure receiving piston through a gap between each tooth with the camshaft, and slides the pressure receiving piston in one axial direction. As a result, the support pin pulls the rear gear component in the sliding direction of the pressure receiving piston, and the front gear component also moves in one axial direction while being pulled in the same direction via the connecting means.

On the other hand, when the internal pressure of the pressure chamber decreases and a spring force of, for example, a compression spring acts on the other end face of the pressure receiving piston, the support pin is moved in the other axial direction as the pressure receiving piston slides in the other axial direction. It projects in one direction from the component and pushes out the front gear component at the tip. Therefore, the rear gear component also moves in the other axial direction while being pulled by the front gear component via the connecting means.

That is, when the entire cylindrical gear moves in one or the other axial direction, a force acts in a direction in which the two gear components are separated from each other. For this reason, the holding force (pressing force) between the inner teeth and the outer teeth of the rotating body and the outer teeth of the camshaft due to the inner and outer teeth provided on the inner and outer circumferences of both gear components is reduced, and the sliding friction resistance between the teeth is reduced.

[0012]

FIG. 1 shows an embodiment in which a valve timing control apparatus for an internal combustion engine according to the present invention is applied to an intake valve side of a DOHC type valve operating mechanism.

In FIG. 1, reference numeral 1 denotes a cylindrical driven sprocket which is a rotating body to which a driving force is transmitted from a crank shaft (not shown) by a timing chain.
A camshaft having a cam rotatably supported by the cam bearing 3a and opening the intake valve (not shown) against the spring force of the valve spring by the rotational force transmitted from the driven sprocket 1. A sleeve 4 inserted in the inner axial direction of the driven sprocket 1 is fixed to one end 2 a of the camshaft 2 from the axial direction by a fixing bolt 5. The sleeve 4 has a large-diameter flange portion 4a on the rear end side fitted to the camshaft one end portion 2a,
Outer teeth 4b are formed substantially at the center of the outer peripheral surface.

The driven sprocket 1 has a cylindrical main body 1a.
And a disk-shaped front cover 7 integrally fastened to the front edge of the sleeve 4 by a fixing bolt 5 to close the front end opening of the cylindrical main body 1a. It is configured. The front end of the cylindrical main body 1a is slidably supported on the outer peripheral surface of the front cover 7, and the inner teeth 1c are formed substantially at the center of the inner peripheral surface.

Between the sleeve 4 and the cylindrical main body 1a, there is provided a cylindrical gear 8 which moves in the axial direction via a drive mechanism described later. The cylindrical gear 8 is composed of two gear components 9, 10 formed by cutting and dividing a long gear in a direction perpendicular to the axis, and the two gear components 9, 10 are each substantially U-shaped in vertical section. And a coil spring 11 and a connecting pin 12 as connecting means mounted in the rear gear component 10.
Are elastically connected in a direction approaching each other.
Further, on the inner and outer circumferences of the respective gear components 9, 10, internal teeth 9a, 10a and external teeth 9b, 10b of both helical teeth are formed, respectively, and these internal and external teeth 9a, 10a, 9b, 10b are formed. The inner teeth 1c of the cylindrical main body 1a and the outer teeth 4b of the sleeve 4 are spirally meshed with each other. Further, a through hole 10c is formed in the inner axial direction of the rear gear component 10. Further, the cylindrical gear 8 is restricted from moving in the maximum forward direction at a position where the front edge of the front gear component 9 abuts against the inner end face of the front cover 7, while the rear gear component 1 is restricted.
The movement in the maximum rearward direction (rightward in the figure) is restricted at the position where the rear end edge of the zero abuts against the inner surface of the large-diameter flange portion 4a via the piston 13 and the compression spring 24.

An annular pressure-receiving piston 13 is provided between the inner periphery of the rear end of the cylindrical main body 1a and the outer periphery of the rear end of the sleeve 4 so as to be slidable in the axial direction of the camshaft. The pressure receiving piston 13 has an annular first pressure receiving chamber 14 formed between the one end face 13a and the rear end face of the rear gear component 10, the other end face 13b, and the inner face of the large diameter flange 4a. A fixing hole 17 is formed to be separated from the formed cylindrical second pressure receiving chamber 15 and to penetrate and fix the support pin 16 at a predetermined location in the circumferential direction in the axial direction. The support pin 16 is formed relatively long and has a head 16a.
Side is press-fitted into the fixing hole 17 and the shaft 1
The rear gear component 10 is slidably supported in the axial direction on the outer peripheral surface of 6b via the through hole 10c. The snap ring 18 fitted radially into a fitting groove provided on the outer periphery of the distal end of the shaft portion 16b locks the rear gear constituting portion 10 with the front edge 16c of the shaft portion 16b. To come into contact with the rear end surface of the device. still,
Seal rings 19 and 20 for sealing between the pressure receiving chambers 14 and 15 are provided on the inner and outer circumferences of the pressure receiving piston 13.

The driving mechanism is formed between the front gear component 9 and the front cover 7, and is connected to the first pressure receiving chamber 14.
A pressure chamber 21 communicating with the teeth 1c, 4b, 9a, 9b, 10a, 10b through gaps between the teeth 1c, 4b, 9a, 9b, 10a, 10b;
There are provided two paths of first and second hydraulic circuits 22 and 23 for supplying and discharging the hydraulic pressure to and from the pressure receiving chamber 15, and a compression spring 24 elastically mounted in the second pressure receiving chamber 15 to urge the pressure receiving piston 13 forward. ing.

The first hydraulic circuit 22 includes a first oil passage 26 formed in the cylinder head 3 and the cam bearing 3 a and along the radial direction of the camshaft 2 and having one end communicating with the oil pump 25. 5, one end is formed in the first oil passage 26, and the other end is formed in the pressure chamber 21 through the diametric hole 27 of the shaft and the through hole 28 of the sleeve 4. And a communication passage 29 for communication. Further, between the first oil passage 26 and the oil pump 25, the upstream / downstream of the first oil passage 26 and the first drain passage 30 are switched (3).
A directional first electromagnetic switching valve 31 is provided.

The second hydraulic circuit 23 is formed inside the cylinder head 3 and the cam bearing 3 a and along the radial direction of the camshaft 2, and has a second oil passage 32 having one end communicating with the oil pump 25, and a fixing bolt 5. Is formed between the outer peripheral surface of the shaft portion and the inner peripheral surfaces of the bolt insertion holes of the camshaft 2 and the sleeve 4, one end of which is in the second oil passage 32, and the other end of which is in the diametrical hole 33 of the sleeve 4. And an annular passage 34 that communicates with the second pressure receiving chamber 15 via the second pressure receiving chamber 15. Further, between the second oil passage 32 and the oil pump 25, a three-directional second electromagnetic switching valve 36 for switching between the upstream and downstream of the second oil passage 32 and the second drain passage 35 is provided.

Further, the first and second electromagnetic switching valves 31, 3
Reference numeral 6 designates relative switching based on control means from a control unit (not shown) for detecting a current engine operating state based on an engine speed or an intake air amount signal output from a crank angle sensor, an air flow meter, or the like. It is supposed to work.

The operation of this embodiment will be described below.
First, for example, when the engine shifts from a low load range to a high load range, an OFF signal is output to the second electromagnetic switching valve 35 as shown in FIG. 2, and the second oil passage 32 and the second drain passage 35 are connected. On the other hand, an ON signal is output to the first electromagnetic switching valve 31 to close the first drain passage 30 and communicate the upstream and downstream of the first oil passage 26. Therefore, while the internal pressure of the second pressure receiving chamber 15 decreases, the first pressure receiving chamber 14
Of the pressure receiving piston 13 slides in the maximum backward direction against the spring force of the compression spring 24 by the hydraulic pressure applied to the one end surface 13a. As a result, the snap ring 18 of the support pin 16 is engaged with the hole edge of the through hole 10c to pull the rear gear component 10 in the sliding direction of the pressure receiving piston 13, and the front gear component 9 also connects the connection pin 12 Follow while being pulled in the same direction. Here, a force acts on the front gear component 9 in a direction away from the rear tooth component 10 against the spring force of the coil spring 11 due to the sliding resistance between the teeth 1c, 4b, 9a, 9b. For this reason, the pressure contact force between the tooth side surfaces of the internal teeth 9a, 10a of the two gear components 9, 10 and the outer teeth 4b of the sleeve 4 decreases, and the external teeth 9b, 10b and the driven sprocket 1
The pressure contact force between the tooth side surfaces of the inner tooth 1c with the inner tooth 1c decreases. Therefore, each tooth 1c, 4b, 9a, 10a, 9b, 10
The sliding frictional resistance between b is reduced, and the entire cylindrical gear 8 can be smoothly moved rearward. As a result,
The phase conversion speed of the relative rotation of the driven sprocket 1 and the camshaft 2 toward one side is increased, and the control response of the valve timing is improved.

On the other hand, when the engine shifts from the high load range to the low load range, the OFF signal is sent to the first electromagnetic switching valve 31 and the second
An ON signal is output to the electromagnetic switching valve 36, and the upstream and downstream of the second oil passage 32 communicate with each other, and the first oil passage 26 and the first drain passage 30 communicate with each other. Therefore, the first
The hydraulic pressure in the pressure receiving chamber 14 and the pressure chamber 21
0 to a low pressure state while the second pressure receiving chamber 15
The hydraulic pressure is supplied to the inside, and a high pressure state is generated. The hydraulic pressure acts on the other end surface 13b, and the pressure receiving piston 13 slides forward as shown in FIG. Thereby, the support pin 16 slides in the through hole 10c and directly presses the rear end face of the front gear component 9 forward at the front edge 16c. Accordingly, with the forward movement of the front gear component 9 due to the combined force of the spring force of the compression spring 15 and the rear gear component 10, the rear gear component 10 is also pulled forward by the spring force of the connecting pin 12 and the coil spring 11 in the same direction. Move to follow. Here, forces act on the two gear components 9 and 10 in directions away from each other, and each tooth 9
a, 9b, 10a, 10b, inner teeth 1c, outer teeth 4
The pressure contact force between the tooth side surfaces of the cylindrical gear b and the sliding frictional resistance decreases, and the entire cylindrical gear 8 can be smoothly moved forward. As a result, the relative rotation phase conversion speed of the first and second motors 1 and 2 to the other side increases.

After the cylindrical gear 8 is moved in the maximum forward direction, OFF is also output to the second electromagnetic switching valve 36, and the second electromagnetic switching valve 36 is turned off.
The internal pressure of the pressure receiving chamber 15 also decreases, and the cylindrical gear 8 is held at the maximum forward position, and the state is set to the movement standby state.

[0024]

As is apparent from the above description, according to the present invention, it is of course possible to sufficiently suppress the occurrence of the impact sound caused by the fluctuation of the rotational torque of the camshaft due to the backlash between the teeth. Since the front and rear gear components can be moved in the axial direction while being separated from each other by the pressure receiving piston and the support pin, the sliding friction resistance between the teeth during the axial movement of the cylindrical gear is reduced. As a result, smooth movement of the cylindrical gear is obtained, the relative rotation phase conversion speed between the rotating body and the camshaft is increased, and the control response of the valve timing is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the operation of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Driven sprocket (rotary body) 1c ... Inner teeth 2 ... Camshaft 4 ... Sleeve 4b ... Outer teeth 8 ... Cylindrical gear 9 ... Front gear component 10 ... Rear gear component 9a, 10a ... Internal teeth 9b, 10b ... external teeth 11 ... coil spring 12 ... connecting pin 13 ... pressure receiving piston 16 ... support pin

Claims (1)

(57) [Claims] 1. A rotating body driven by an engine and having inner teeth on an inner periphery, a camshaft to which rotational force is transmitted from the rotating body and having outer teeth on an outer periphery, and between the rotating body and the camshaft. At least one of the helical inner and outer teeth meshes with the inner teeth and the outer teeth, and the two gear components divided in the axial direction are elastically connected to each other via connecting means in a direction approaching each other. A cylindrical gear, and a drive mechanism for moving the cylindrical gear in a camshaft axial direction to convert a relative rotation phase between the rotating body and the camshaft. A pressure receiving piston is slidably provided in the camshaft axial direction between the camshaft and the camshaft, and one of the gear components on the pressure receiving piston side is slid in the axial direction on a support pin fixed to the pressure receiving piston from the axial direction. A valve timing control device for an internal combustion engine, which is freely connected.