JPH051514A - Valve timing control device for internal combustion engine - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] It is possible to improve the manufacturing work efficiency and reduce the cost, and to obtain highly accurate and responsive valve timing control. A device that utilizes the rotational torque fluctuation of the camshaft 1 for the relative rotation of the camshaft 1 and the driven sprocket 3, and the forward / reverse relative rotation conversion position of the both 1 and 3 is determined by a stopper mechanism 4. And a pair of spring clutches 5 and 6 arranged in series, which are held by tightening and releasing the tightening, and the relative switching between the tightening and releasing of the spring clutches 5 and 6 is operated in accordance with the engine operating state. The mechanism 7 is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for variably controlling the opening / closing timing of an intake valve or an exhaust valve of an internal combustion engine according to the operating condition.

[0002]

2. Description of the Related Art Various conventional valve timing control devices of this kind have been provided, and an example thereof is disclosed in U.S. Pat. No. 4,231,330.

In brief, a camshaft for controlling the opening / closing of intake / exhaust valves has external teeth formed on the outer periphery of the front end portion, and a sleeve is screwed to the front end portion through the male and female screw portions of each other. It is fixed. On the other hand, the sprocket, which is arranged and supported outside the sleeve and the front end of the camshaft, is provided with a gear on the outer periphery of the cylindrical body through which the rotational force of the engine is transmitted through a timing chain, and an inner periphery of Teeth are formed. Then, between the inner teeth and the outer teeth of the cam shaft, a cylindrical gear in which at least one of the inner and outer teeth is formed as a helical tooth is meshed, and the cylindrical gear is The intake / exhaust valve opening / closing timing is controlled by moving the cam shaft relative to the sprocket by moving the cam shaft in the axial direction by the hydraulic pressure of the hydraulic circuit or the spring force of the compression spring according to the engine operating state. It is supposed to do.

[0004]

However, in the above-mentioned conventional valve timing control device, the sprocket and the cam shaft are formed by using the helical teeth formed on at least one of the inner and outer circumferences of the cylindrical gear. The helical teeth are required to be machined with high precision in order to ensure good meshing precision with the internal teeth of the sprocket or the external teeth of the camshaft. As a result, the machining work of the helical teeth becomes complicated, resulting in a reduction in machining work efficiency and a rise in machining cost.

Further, since the relative rotation between the camshaft and the sprocket is changed only by moving the tubular gear in the axial direction, it is possible to reduce the mesh frictional resistance between the tubular gear and the inner and outer teeth. As a result, the movement delay in the axial direction is likely to occur, and the responsiveness of the valve timing control may be deteriorated.

[0006]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned conventional circumstances, and particularly restricts the forward and reverse maximum relative rotation between the rotating body and the camshaft. A stopper mechanism is provided, and a pair of spring clutches, which are arranged in series in the axial direction along the inner peripheral surface of the cylindrical main body of the rotating body and are wound in opposite directions, are provided. While fixing the outer end portion to the camshaft, the respective inner end portions are provided so as to oppose each other, and further, the opposing inner end portions are pressed in the circumferential direction in accordance with the engine operating state, and the respective springs for the tubular main body are provided. It is characterized in that a switching mechanism for switching the relative tightening or loosening action of the clutch is provided.

[0007]

In the engine low load region, for example, when the inner end portion of the one side spring clutch is pressed in the circumferential direction by the switching mechanism, the one side spring clutch relaxes with respect to the inner peripheral surface of the cylindrical body of the rotating body. On the other hand, the spring clutch on the other side, where the switching mechanism does not work, expands outward due to its own torsion spring force and tightens the inner peripheral surface of the tubular main body, and the rotating body and the camshaft rotate relative to each other in the forward direction. Regulate. Therefore, the camshaft rotates in the negative direction due to the negative rotational torque fluctuation generated by the spring force of the valve spring, and the stopper mechanism restricts the maximum rotation thereof. At the same time, the positive rotation is restricted by the spring clutch on the other side with respect to the positive rotational torque fluctuation. Therefore, the camshaft is reliably held in the relative rotation position that delays the closing timing of the intake valve, for example.

On the other hand, when the engine shifts to a high load region, for example, the switching mechanism switches the spring clutch on the other side to the relaxed state and the spring clutch on the one side to the tightened state. Therefore, the camshaft rotates in the positive direction in accordance with the positive rotation torque fluctuation, and the stopper mechanism restricts the rotation beyond the maximum normal rotation. Here, even if a negative rotational torque fluctuation occurs due to the spring force of the valve spring and the cam shaft tries to reverse, the reverse rotation is restricted by the tightening force of the spring clutch on the one side with respect to the tubular body. Therefore, the camshaft is securely held in the relative rotation position that advances the closing timing of the intake valve.

[0009]

1 and 2 show an embodiment of the present invention applied to a DOHC type internal combustion engine of an automobile, in which 1 is supported by a cam bearing 2 above a cylinder head, and an intake valve is provided with a camshaft (not shown). The cam shaft 3 which is opened and closed by means of the driven shaft is a driven sprocket, which is a rotating body, which is provided on the outer periphery of the one end 1a of the cam shaft 1 and to which the driving force is transmitted from the drive sprocket of the crank shaft through the timing chain. A stopper mechanism 4 and two spring clutches 5 and 6 are provided between the one end portion 1a and the driven sprocket 3. Further, the intermittent action of the spring clutches 5 and 6 is relatively switched by the switching mechanism 7.

More specifically, the camshaft 1 will be described.
Has a stepped cylindrical sleeve 8 fixed to one end 1a by a mounting bolt 9 in the axial direction. Further, the sleeve 8 is provided with a tubular member 10 fitted in the small diameter portion and the medium diameter portion on the tip side, and a support member 12 having a substantially U-shaped cross section arranged at the tip edge of the small diameter portion by the mounting bolt 9. It is fixed together. A large-diameter cover member 13 having a substantially U-shaped cross section is fixed to the front end side of the support member 12 by a bolt 14. Further, the tubular member 10 is formed with a locking groove 11 in the axial direction, and as shown in FIGS. 4 and 5, a semicircular arc-shaped cutout portion 15 is formed in the outer peripheral wall on the tip end side of the lower end portion.

The driven sprocket 3 comprises a cylindrical main body 3a having a stepped cylindrical shape, and a gear 3b provided on the outer periphery of the end of the cylindrical main body 3a and around which a timing chain is wound. The cylindrical main body 3a is composed of: Sleeve 8 at one end of gear 3b
Is rotatably supported on the outer peripheral surface of the large-diameter portion 8a, and a guide pin 16 is planted in the lower part of the other end along the radial direction.

As shown in FIGS. 1 and 3, the stopper mechanism 4 is provided with a projecting portion 17 integrally formed on the end face of the cylindrical body 3a on the one end side in the axial direction, and is opposed to the end face on the one end side. The large-diameter portion 8a of the sleeve 8 is formed with a stopper groove 18 which is notched in a circular arc shape along the radial direction and into which the projection portion 17 is fitted. Both end edges 18a and 18b of the stopper groove 18 are formed in the projection portion 17a. The relative rotation position of the camshaft 1 with respect to the sprocket 3 in the maximum positive and negative directions is restricted at the positions where it abuts on both sides of the.

The first and second spring clutches 5 and 6
Are interposed between the cylindrical member 10 and the cylindrical main body 3a, are provided in series in the axial direction, and each outer peripheral edge is arranged close to the inner peripheral surface 3c of the cylindrical main body 3a. There is.
Further, as shown in FIGS. 4 and 5, the first spring clutch 5 on the side of the cover member 13 is wound in the opposite directions, and the first spring clutch 5 on the side of the cover member 13 is right-handed in the figure, and the second spring clutch 6 on the side of the camshaft one end 1a is shown in the figure. It is formed to the left. Further, the outer end portions 5a and 6a of the spring clutches 5 and 6 which are bent inward are fixed to both ends of the locking groove 11 of the tubular member 10, while they are bent inward. The inner end portions 5b and 6b, which are offset from each other in the axial direction, are arranged to face each other with a predetermined gap X in the circumferential direction.

The switching mechanism 7 is provided on the outer peripheral surface of the cylindrical main body 3a and a slider 19 which is provided between the support member 12 and the cover member 13 so as to be slidable in the axial direction and has a substantially U-shaped cross section. A compression spring 20 which is provided along the slider 1 and biases the slider 19 to the left in the figure;
9 and the pressure chamber 21 formed between the cover member 13,
A hydraulic circuit 22 for introducing hydraulic pressure into the pressure chamber 21 is provided.

The slider 19 is a disk-shaped main body 19a.
A flange portion 19b that slidably contacts the inner peripheral surface of the cylindrical portion of the cover member 13 is integrally provided on the outer peripheral edge of the cover member 13, and a pair of relatively long locking members 2 is provided on the lower inner end surface of the main body 19a.
3, 24 are provided so as to protrude along the axial direction of the camshaft. The locking members 23 and 24 are combined with each other as shown in FIG. 6, and plate-shaped base portions 23a and 24a fixed by bolts 26 and 26 inserted into bolt holes 25 formed in the main body 19a. , Each base 23
It is composed of a pair of locking shafts 23b and 24b which are inserted from the upper end edges of a and 24a through the notches 15 into the gaps X of the spring clutches 5 and 6, respectively. The bolt hole 25 is formed in an arc shape which is continuous in the circumferential direction, and adjustment gaps 25a and 25b are formed on the left and right. Further, the bolt insertion holes 27, 27 formed in the base portion 24a on one side
Has its inner diameter set to be relatively larger than the outer diameters of the shaft portions of the bolts 26, 26.
The relative position of 24a is shifted in the circumferential direction so that the locking shaft 23
The span between b and 24b can be finely adjusted. Further, each of the locking shafts 23b and 24b has a rectangular cross section, and the outer surfaces of the locking shafts 23b and 24b contact the inner end portions 5b and 6b of the spring clutches 5 and 6 from the inside. Further, the flange portion 19b supports the other end portion of the compression spring 20 whose one end portion is supported by the step portion 3c of the cylindrical main body 3a, and has the lower end portion which is formed with the guide pin as shown in FIG. An inclined long groove 28 into which 16 is inserted is formed.
The long groove 28 is formed on the slider 19 via the guide pin 16 as the slider 19 moves linearly in the axial direction.
Is rotated forward and backward in a predetermined direction. Also,
The maximum leftward movement of the slider 19 is restricted by the step portion 29 of the support member 12, and the maximum rightward movement is restricted by the tubular member 10.

The hydraulic circuit 22 is branched from the oil main gallery 30 and is formed in a radial direction of the cam bearing 2 and the cam shaft 1, and an introduction passage 31 and an inner central axial direction of the cam shaft 1 and the mounting bolt 9. An oil chamber 33 formed between the formed axial passage 32, the head of the mounting bolt 9 and the inner end surface of the cover member 13, and communicating with the axial passage 32, and a radial direction of the peripheral wall of the support member 12. It has a radial hole 34 that is bored and connects the oil chamber 33 and the pressure chamber 21.

At the upstream end of the introduction passage 31, a solenoid valve 37 for introducing and shutting off the hydraulic pressure sent from the oil pump 35 by an output signal from the electronic controller 36.
Is provided. The electronic controller 36 detects the current engine operating state based on an output signal from a crank angle sensor (not shown), an air flow meter, etc., and detects the electromagnetic valve 3
9 is ON / OFF controlled.

The operation of this embodiment will be described below.

First, in the low engine load region, for example, an OFF signal (non-energized) is output to the solenoid valve 37 by the electronic controller 36, and the introduction of hydraulic pressure from the oil pump 35 to the pressure chamber 21 is blocked. Therefore, the slider 19
The front end surface of the support member 1 by the spring force of the compression spring 20.
It is held at the maximum leftward position (the position shown in FIG. 1) where it abuts the second step portion 29. Then, in such a state, the slider 19 rotates in the upward direction (counterclockwise direction in FIG. 2) by the guide pin 16 via the long groove 28 as shown by the solid line in FIG. 7.

Therefore, the second locking shaft 24b presses the inner end portion 6b of the second spring clutch 6 in the counterclockwise direction in the figure, as shown in FIG. Therefore, the second spring clutch 6 is entirely deformed to a reduced diameter state against its own spring force, releasing the tightening of the inner end surface 3c of the tubular body 3a, and the tubular member 10 to the tubular body 3a. Allows forward and reverse free rotation. On the other hand, the first spring clutch 5 expands its diameter by its own spring force, and the inner peripheral surface 3c of the cylindrical main body 3a.
Tighten. As a result, rotation of the tubular member 10 in the negative direction (counterclockwise direction in FIG. 2) is allowed with respect to the tubular body 3a, but rotation in the positive direction is restricted.

Therefore, in this state, when the negative rotation torque generated when the intake valve is closed acts on the camshaft 1,
As shown in FIG. 3, the camshaft 1 rotates in the negative direction and hits the one end 18a of the protrusion 17 to restrict further rotation. Here, when a positive rotational torque is generated in the camshaft 1 and the camshaft 1 tries to rotate in the clockwise direction (positive direction) in the figure, as described above, the first spring clutch 5 tightens the tubular body 3a. Due to the action, the forward rotation of the camshaft 1 is reliably regulated. For this reason, the camshaft 1 is held in the relative rotation position where the free rotation of the camshaft 1 with respect to the driven sprocket 3 in both the positive and negative directions is restricted and the closing timing of the intake valve is delayed.

On the other hand, when the engine shifts to the high load range,
The solenoid valve 37 is turned on (energized) and the hydraulic oil pumped from the oil pump 35 is introduced into the pressure chamber 21 through the introduction passage 31, the axial passage 32, the oil chamber 33, and the radial passage 34. 21 immediately becomes high pressure. Therefore, when the slider 19 moves to the rightmost in the figure until the base portions 23a and 24a abut the end surface of the tubular main body 3a against the spring force of the compression spring 20, as shown by the alternate long and short dash line in FIG. At the same time, the guide pin 16 rotates through the long groove 28 in the downward direction (clockwise in FIG. 2) as shown by the dashed line in FIG. Therefore, as shown in FIG. 5, the pressing force of the second spring clutch 6 by the second locking shaft 24b is released, and the first locking shaft 23b moves the inner end portion 5b of the first spring clutch 5 in the figure. Press in the clockwise direction. Therefore, contrary to the above, the entire diameter of the first spring clutch 5 is contracted and deformed to release the fastening to the tubular body 3a, while the second spring clutch 6 is expanded by its own spring force and is tubular. The inner peripheral surface 3c of 3a is tightened. This allows the cylindrical member 10 to rotate in the positive direction (clockwise in FIG. 2) with respect to the cylindrical body 3a, but restricts the rotation in the negative direction.

Therefore, the camshaft 1 rotates in the positive direction due to the positive rotational torque fluctuation, and the other end 18b of the stopper groove 18 abuts on the protrusion 17 to prevent further normal rotation. Here, when a negative rotation torque is generated in the camshaft 1 and the camshaft 1 tries to rotate in the counterclockwise direction (negative direction), the tightening action of the second spring clutch 6 reliably restricts the rotation of the camshaft 1 in the negative direction. To be done. For this reason, the camshaft 1 is held in the relative rotation position where the free rotation in both the positive and negative directions is restricted and the closing timing of the intake valve is advanced.

The tightening action of the spring clutches 5 and 6 becomes stronger as the positive and negative rotational torques increase, so that a reliable rotation regulating action of the camshaft 1 can be obtained.
Further, the hydraulic oil in the pressure chamber 21 when the high load region is shifted to the low load region is promptly discharged to the outside via the solenoid valve 37.

Further, in this embodiment, since the relative rotation of the camshaft 1 uses positive and negative rotational torque fluctuations, valve timing switching control can be performed in response to changes in engine operation. Further, the positioning of the locking shafts 23b and 24b with respect to the spring clutch inner ends 5b and 6b can be finely adjusted after the components are assembled through the adjustment gaps 25a and 25b. High processing accuracy and assembly accuracy are not required. Therefore, the manufacturing and assembling workability is improved, and the cost can be reduced. Further, the present invention is not limited to the above-described embodiment, and the switching mechanism 7 can be configured differently, for example. It is also possible to apply it to the exhaust valve side or both the intake and exhaust valves.

[0026]

As is apparent from the above description, according to the present invention, the relative rotation between the camshaft and the rotating body is made by utilizing the rotational torque fluctuation of the camshaft instead of the conventional cylindrical gear. Therefore, the manufacturing and processing work efficiency can be improved.

Further, the forward / reverse relative rotation conversion of the cam shaft and the rotating body is converted into a stopper mechanism, a plurality of spring clutches arranged in series, and tightening / tightening of each spring clutch.
Since it is performed by the switching mechanism that switches the release, the valve timing control with high accuracy and excellent responsiveness can be obtained according to the engine operating state.

[Brief description of drawings]

FIG. 1 is a sectional view taken along the line AA of FIG. 2 showing an embodiment of a valve timing control device according to the present invention.

FIG. 2 is a view on arrow B of FIG.

FIG. 3 is a view on arrow C of FIG.

FIG. 4 is a sectional view taken along the line DD of FIG.

5 is a sectional view taken along line EE of FIG.

6 is a cross-sectional view taken along the line FF of FIG.

FIG. 7 is a sectional view taken along line GG of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Camshaft, 3 ... Driven sprocket (rotating body), 3a ... Cylindrical main body, 3c ... Inner peripheral surface, 4 ... Stopper mechanism, 5, 6 ... Spring clutch, 5a, 6a ... External,
5b, 6b ... Inner end. 7 ... Switching mechanism.

Front Page Continuation (72) Inventor Yoshiharu Kitamura 1170, Ako, Komagane-shi, Nagano 3 Japan Article Co., Ltd. (72) Inventor Tatsuo Komatsu 4056 Sakuradai, Nakatsu, Aikawa-cho, Aiko-gun, Kanagawa Japan Article Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. A rotary body, to which a driving force of an engine is transmitted, and a cam shaft are rotated forward and backward relative to each other due to fluctuations in the rotational torque of the cam shaft, and the valve opening / closing timing is variably controlled. A valve timing control device for controlling a forward / reverse maximum relative rotation between the rotary body and the camshaft, the valve timing control device being provided along an inner peripheral surface of a cylindrical main body of the rotary body. A pair of spring clutches that are arranged in series in the axial direction and are wound in opposite directions, and the outer ends of the spring clutches are fixed to the camshaft, while the inner ends are fixed. A switching mechanism is provided which is opposed to each other and further presses the opposed inner ends in the circumferential direction according to the engine operating state to switch the relative tightening or loosening action of each spring clutch with respect to the tubular body. The valve timing control apparatus for an internal combustion engine according to symptoms.