JPH0628203U - Valve timing control device for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the sliding frictional resistance between the teeth during the movement of the tubular gear, to ensure the smooth mobility of the tubular gear, and to improve the responsiveness of the valve timing control. [Structure] A tubular gear 8 meshed between a driven sprocket 1 and a camshaft 2 via respective teeth 9a, 10a, 9b, 10b is moved in the axial direction by a drive mechanism, so that a relative rotation of the two is obtained. Convert the dynamic phase. Both 1, 2
The pressure receiving piston 13 and the support pin 16 provided between the two gear component parts 9 and 10 are moved in the axial direction while being separated from each other.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement in a valve timing control device that variably controls opening / closing timings of intake / exhaust valves of an internal combustion engine according to operating conditions.

[0002]

[Prior art]

 An example of this type of valve timing control device is described in Japanese Patent Application Laid-Open No. 61-279713 previously filed by the present applicant.

This device includes at least one of teeth provided on the inner and outer circumferences between a timing pulley to which drive is transmitted from a crankshaft of an engine and a camshaft to which rotational force is transmitted from the timing pulley. A cylindrical gear, which is a helical gear, is inserted while meshing with the internal teeth of the timing pulley and the external teeth of the camshaft, and the cylindrical gear is inserted through a drive mechanism according to the engine operating condition. By moving the camshaft in the axial direction, the relative rotation between the timing pulley and the camshaft is obtained to control the opening / closing timing of the intake / exhaust valve.

Further, the cylindrical gear is divided into two parts by cutting in a direction perpendicular to the axis from substantially the center, and two front and rear gear structures each having an external tooth and an internal tooth of the same tooth profile formed on a helical tooth are formed. It has a section. The two gear structure parts are movably connected to each other by a connecting pin extending in the inner axial direction across the both parts so as to be movable in a direction in which they are separated from each other or approaching each other. Coil springs mounted between them are urged in directions toward each other and elastically connected.

Due to the elastic coupling action of both gear component parts, the apparent tooth thickness of these inner and outer teeth is increased to shift the tooth trace when the gear component parts move in the axial direction. By pressing the tooth flanks of the inner and outer teeth against the tooth flanks of the inner and outer teeth, it is possible to sufficiently reduce the backlash during the meshing movement of the timing pulley and the cam shaft with respect to the inner and outer teeth. . As a result, it is possible to sufficiently suppress the generation of hammering sound due to the collision between the teeth due to the fluctuation of the forward / reverse rotational torque of the camshaft caused by the spring reaction force of the valve spring.

[0006]

[Problems to be solved by the device]

 However, in the above-mentioned conventional valve timing control device, when the engine shifts from the low load region to the high load region, the front gear component is driven by the hydraulic pressure in the pressure chamber at the front end side of the front gear component. When moving backward, at the same time, the rear gear component is also pushed by the rear end face of the front gear component, and the two components move backward in a state where they are always close to each other. That is, the both gear component parts move backward while always approaching each other by a strong combined force of the spring force of the coil spring and the hydraulic pressure in the pressure chamber. For this reason, the pressure contact force of each outer tooth of each gear component with respect to the inner tooth and the pressure contact force of each inner tooth with respect to the outer tooth become much stronger, so that the sliding friction resistance between each tooth increases. As a result, the backward movement speed of the entire cylindrical toothed gear decreases, the phase conversion speed of the relative rotation between the timing pulley and the cam shaft becomes slow, and the valve timing control responsiveness deteriorates.

Further, the engine operating state shifts from the high load region to the low load region, and the front gear component is pushed backward by the rear gear component by the spring force of the compression spring of the drive mechanism, and the entire tubular gear is moved. The same problem is caused when moving it forward.

[0008]

[Means for Solving the Problems]

 The present invention has been devised in view of the above-mentioned conventional problems. In particular, a pressure-receiving piston is provided between a rotating body and a camshaft so as to be slidable in the camshaft axial direction, and It is characterized in that one gear component on the pressure receiving piston side is connected to a support pin fixed in the axial direction so as to be slidable in the axial direction.

[0009]

[Action]

 According to the present invention having the above-mentioned configuration, when hydraulic pressure is supplied to a pressure chamber provided on the front end side of the front gear component, for example, as the engine operating state changes, the hydraulic pressure is applied to each gear component, the rotor, and the camshaft. It acts on one end surface of the pressure receiving piston through the gaps between the teeth, and causes the pressure receiving piston to slide 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 the 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 the spring force of, for example, a compression spring acts on the other end surface of the pressure receiving piston, this time, as the pressure receiving piston slides in the other axial direction, the support pin moves rearward. It projects in one direction from the gear structure and pushes out the front gear structure 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 tubular gear moves in one axial direction or the other axial direction, a force acts in a direction in which both gear component parts are separated from each other. Therefore, the holding force (pressure contact force) between the inner teeth and the outer teeth on the inner and outer circumferences of both gear components to the inner teeth of the rotor and the outer teeth of the camshaft is reduced, and the sliding frictional resistance between the teeth is reduced.

[0012]

【Example】

 FIG. 1 shows an embodiment in which a valve timing control device for an internal combustion engine according to the present invention is applied to the intake valve side of a DOHC type valve 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 crankshaft (not shown) by a timing chain, and 2 has one end 2 a rotatably supported by a cam bearing 3 a of a cylinder head 3. A camshaft having a cam that opens the intake valve (not shown) against the spring force of the valve spring by the rotational force transmitted from the driven sprocket 1, and the camshaft 2 has one end 2a In the driven sprocket 1, a sleeve 4 inserted in the inner axial direction of the driven sprocket 1 is fixed from the axial direction by a fixing bolt 5. In this sleeve 4, a large-diameter flange portion 4a on the rear end side is fitted in the camshaft one end portion 2a, and outer teeth 4b are formed at a substantially central position on the outer peripheral surface.

The driven sprocket 1 is fixed to the gear 1b integrally provided on the outer periphery of the rear end of the tubular main body 1a and the front end edge of the sleeve 4 together with a fixing bolt 5 to fix the driven sprocket 1 to the tubular main body 1a. And a disk-shaped front cover 7 that closes the front end opening. 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.

A tubular gear 8 that moves in the axial direction via a drive mechanism described later is interposed between the sleeve 4 and the tubular body 1a. The tubular gear 8 is composed of two gear components 9 and 10 formed by cutting and dividing a long gear in the direction perpendicular to the axis. Both gear components 9 and 10 are substantially U-shaped in vertical cross section. And is elastically connected in a direction in which they approach each other by a coil spring 11 and a connecting pin 12 which are connecting means mounted in the rear gear component 10. Inner and outer teeth 9a, 10a and 9b, 10b, which are helical teeth on both sides, are formed on the inner and outer peripheries of the respective gear components 9, 10, and these inner and outer teeth 9a, 10a, 9b, An inner tooth 1c of the tubular body 1a and an outer tooth 4b of the sleeve 4 are spirally meshed with each other at 10b. Further, a through hole 10c is formed in the inner gear direction of the rear gear component 10. Further, the tubular gear 8 is restricted from moving in the maximum forward direction at the position where the front end edge of the front gear forming portion 9 abuts on the inner end surface of the front cover 7, while the rear end of the rear gear forming portion 10 is restricted. The maximum rearward movement (rightward in the figure) is restricted at the position where the edge abuts 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 circumference of the rear end of the cylindrical main body 1a and the outer circumference of the rear end of the sleeve 4 so as to be slidable in the camshaft axial direction. The pressure receiving piston 13 includes an annular first pressure receiving chamber 14 formed between one end surface 13a and a rear end surface of the rear gear component 10, an other end surface 13b, and an inner surface of the large-diameter flange portion 4a. It is separated from the cylindrical second pressure receiving chamber 15 formed therebetween, and a fixing hole 17 through which the support pin 16 is inserted and fixed is axially formed at a fixed position in the circumferential direction. The support pin 16 is formed to have a relatively long length, the head 16a side is press-fitted and fixed in the fixing hole 17, and the rear gear forming portion 10 is provided on the outer peripheral surface of the shaft portion 16b through the through hole 10c. Is supported slidably in the axial direction. Further, the snap ring 18 fitted in the fitting groove formed on the outer periphery of the front end of the shaft portion 16b is engaged with the rear gear component 10 by the snap ring 18, and the tip edge 16c of the shaft portion 16b is fixed to the front gear component portion. The rear end surface 9 is abutted appropriately. Sealing 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 drive mechanism is formed between the front gear forming section 9 and the front cover 7, and is provided in the first pressure receiving chamber 14 via the gaps between the teeth 1c, 4b, 9a, 9b, 10a, 10b. Pressure chamber 21 communicating with each other, two first and second hydraulic circuits 22 and 23 for supplying and exhausting hydraulic pressure to and from the pressure chamber 21 and the second pressure receiving chamber 15, and mounted in the second pressure receiving chamber 15 The pressure receiving piston 13 is provided with a compression spring 24 that biases the piston 13 forward.

The first hydraulic circuit 22 is formed in the cylinder head 3, the cam bearing 3 a and along the radial direction of the cam shaft 2 and has a first oil passage 26 having one end communicating with the oil pump 25, and a fixing bolt. 5 is formed along the axial direction in the shaft portion of 5, and the one end is in the first oil passage 26, and the other end is in the pressure chamber 21 through the diameter hole 27 of the shaft portion and the through hole 28 of the sleeve 4, respectively. And a communication path 29 communicating with each other. A three-way first electromagnetic switching valve 31 is provided between the first oil passage 26 and the oil pump 25 to switch between the upstream and downstream of the first oil passage 26 and the first drain passage 30.

The second hydraulic circuit 23 is formed in the cylinder head 3, the cam bearing 3 a, and along the radial direction of the cam shaft 2, and has a second oil passage 32 whose one end communicates with the oil pump 25, and the 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 cam shaft 2 and the sleeve 4, one end of which is in the second oil passage 32 and the other end of which is the diametrical hole of the sleeve 4. And an annular passage 34 communicating with the second pressure receiving chamber 15 via 33. Further, between the second oil passage 32 and the oil pump 25, a three-way second electromagnetic switching valve 36 that switches 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, 36 detect the current engine operating state based on the engine speed or intake air amount signal output from a crank angle sensor, an air flow meter, or the like. The switching operation is performed relative to each other based on the control means from the external control unit.

The operation of this embodiment will be described below. First, for example, when the engine shifts from the low load region to the high load region, 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 output. On the other hand, an ON signal is output to the first electromagnetic switching valve 31 to close the first drain passage 30 to connect the upstream and downstream of the first oil passage 26. Therefore, the internal pressure of the second pressure receiving chamber 15 decreases and the internal pressure of the first pressure receiving chamber 14 increases via the pressure chamber 21, and the pressure receiving piston 13 causes the spring force of the compression spring 24 by the hydraulic pressure applied to the one end surface 13a. It slides in the maximum backward direction against. 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 is also connected to the connecting pin. It moves following while being pulled in the same direction via 12. Here, the front gear component 9 acts on the 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. To do. For this reason, the pressure contact force between the tooth flanks of the inner teeth 9a, 10a of both gear component parts 9, 10 and the outer tooth 4b of the sleeve 4 is reduced, and the outer teeth 9b, 10b and the driven sprocket 1 are also reduced. The pressure contact force between the tooth side surface and the inner tooth 1c is reduced. Therefore, the sliding frictional resistance between the teeth 1c, 4b, 9a, 10a, 9b, 10b is reduced, and the entire tubular gear 8 can be smoothly moved backward. As a result, the phase conversion speed of the relative rotation of the driven sprocket 1 and the cam shaft 2 to 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, an OFF signal is output to the first electromagnetic switching valve 31 and an ON signal is output to the second electromagnetic switching valve 36, respectively, and the second oil passage The upstream and downstream sides of 32 are communicated with each other, and the first oil passage 26 and the first drain passage 30 are communicated with each other. Therefore, while the hydraulic pressure in the first pressure receiving chamber 14 and the pressure chamber 21 is discharged from the first drain passage 30 to be in a low pressure state, the hydraulic pressure is supplied in the second pressure receiving chamber 15 to be in a high pressure state. By acting on the other end surface 13b, the pressure receiving piston 13 slides forward as shown in FIG. As a result, the support pin 16 slides in the through hole 10c and directly presses the rear end face of the front gear component 9 forward with the front edge 16c. Therefore, the rear gear component 10 is also pulled forward by the combined force of the compression spring 15 and the front gear component 9 along with the forward movement of the front gear component 9 via the spring force of the connecting pin 12 and the coil spring 11. While moving in the same direction. Here, in both gear component parts 9 and 10, a force acts in a direction away from each other, and the pressure contact force between the tooth side surfaces of the teeth 9a, 9b, 10a and 10b and the inner teeth 1c and the outer teeth 4b decreases. The sliding friction resistance is reduced, and the entire tubular gear 8 can be smoothly moved forward. As a result, the relative rotational phase conversion speed of the both 1 and 2 to the other side increases.

After the tubular gear 8 is moved in the maximum forward direction, OFF is also output to the second electromagnetic switching valve 36, the internal pressure of the second pressure receiving chamber 15 is also reduced, and the tubular gear 8 is moved to the maximum. Hold it in the forward position and put it in a movement standby state.

[0024]

[Effect of device]

 As is clear from the above description, according to the present invention, it is of course possible to sufficiently suppress the occurrence of a collision hammering sound due to the rotational torque fluctuation of the camshaft due to the backlash between the teeth. Since the piston and the support pin can move the front and rear gear components in the axial direction in a state of being separated from each other, the sliding friction resistance between the teeth during the axial movement of the tubular gear is reduced. As a result, the smooth movement of the cylindrical gear is obtained, the relative rotational phase conversion speed between the rotating body and the cam shaft is increased, and the valve timing control response is improved.

[Brief description of drawings]

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

FIG. 2 is a vertical sectional view showing the operation of this embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Followed sprocket (rotating body) 1c ... Inner tooth 2 ... Cam shaft 4 ... Sleeve 4b ... Outer tooth 8 ... Cylindrical gear 9 ... Front gear component 10 ... Rear gear component 9a, 10a ... Inner tooth 9b, 10b ... External teeth 11 ... Coil spring 12 ... Connecting pin 13 ... Pressure receiving piston 16 ... Support pin

Claims (1)

[Scope of utility model registration request] 1. A rotating body driven by an engine and having inner teeth on its inner circumference, a camshaft to which rotational force is transmitted from the rotating body and having outer teeth on its outer circumference, and between the rotating body and the camshaft. In addition, at least one of the helical tooth-shaped inner and outer teeth meshes with the inner tooth and the outer tooth, and both gear component parts that are axially divided into two are elastically connected to each other through connecting means in a direction in which they approach each other. A valve timing control device comprising: a tubular gear, and a drive mechanism that moves the tubular gear in the camshaft axial direction to convert the relative rotational phase between the rotary body and the camshaft. A pressure receiving piston is provided slidably in the cam shaft axial direction between the cam shaft and the gear pin on the pressure receiving piston side is slid in the axial direction on a support pin fixed to the pressure receiving piston in the axial direction. A valve timing control device for an internal combustion engine, which is freely connected.