JP2958157B2 - 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 a valve timing control apparatus for variably controlling the opening / closing timing of an intake valve or an exhaust valve of an internal combustion engine in accordance with an operation state.

[0002]

2. Description of the Related Art Various types of conventional valve timing control devices have been provided, such as the one disclosed in U.S. Pat. No. 4,231,330.

[0003] In brief, a camshaft for controlling the opening and closing of an intake / exhaust valve has external teeth formed on the outer periphery of a front end, and a sleeve is screwed to the front end via mutual male and female threads. Fixed. On the other hand, the sprocket, which is disposed and supported outside the front end of the sleeve and the camshaft, has a gear on the outer periphery of the cylindrical main body through which the rotational force of the engine is transmitted via a timing chain, and has an inner periphery on the inner periphery. Teeth are formed. And, between the internal teeth and the external teeth of the camshaft, at least one of the inner and outer peripheral teeth is meshed with a cylindrical gear formed as a helical tooth. Controlling the opening and closing timing of intake and exhaust valves by rotating the camshaft relative to the sprocket by moving it in the axial direction of the camshaft by the hydraulic pressure of the hydraulic circuit and the spring force of the compression spring according to the engine operating state It is supposed to.

[0004]

However, in the above conventional valve timing control device, the sprocket and the camshaft use a helical tooth 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 accuracy with the internal teeth of the sprocket or the external teeth of the camshaft. As a result, the work of processing the helical teeth becomes complicated, resulting in a decrease in the efficiency of the processing operation and an increase in the processing cost.

Further, since the relative rotation between the camshaft and the sprocket is converted only by moving the cylindrical gear in the axial direction, the friction between the cylindrical gear and the internal and external teeth is reduced. For this reason, the movement delay in the axial direction is likely to occur, and the response of the valve timing control may be deteriorated.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has been developed in consideration of the driving force of an engine .
A valve timing control device that variably controls the opening / closing timing of a valve by rotating a rotating body driven to rotate and a camshaft to which a rotating force is transmitted from the rotating body forward and reverse relative rotation,
A stopper mechanism that is provided between the rotating body and the camshaft and regulates the forward and reverse maximum relative rotation of the two, and is disposed in series in the axial direction along the inner peripheral surface of the cylindrical body of the rotating body. And a pair of spring clutches wound in opposite directions to each other, and respective outer end portions of both spring clutches respectively fastened to the camshaft , provided opposite to each other.
Around one of the inner ends of the two spring clutches.
And selectively pressed in the direction, and a switching mechanism for switching the relaxed or tightened state with respect to the tubular body, said switching device
The spring clamp on one side whose inner end is pressed by the
The switch relaxes the cylindrical main body and rotates the cylindrical main body in the forward and reverse directions.
The other spring, which is allowed but the inner end is not pressed
A clutch tightens the inner peripheral surface of the tubular main body, and
Restricts camshaft relative rotation to either forward or reverse
It is characterized by having been constituted so that .

[0007]

For example, in the low engine load range, when the inner end of one spring clutch is pressed in the circumferential direction by the switching mechanism, the one spring clutch relaxes against 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 act is expanded outward by its own torsion spring force to tighten the inner peripheral surface of the cylindrical main body, and the relative rotation of the rotating body and the cam shaft in the forward direction Regulate. Therefore, the camshaft rotates in the negative direction due to the negative rotation torque fluctuation generated by the spring force of the valve spring, and its maximum rotation is regulated by the stopper mechanism. At the same time, the forward rotation is regulated by the other side spring clutch with respect to the positive rotation torque fluctuation. Therefore, the camshaft is reliably held at the relative rotation position that delays the closing timing of the intake valve, for example.

On the other hand, when the engine shifts to, for example, a high load region, the switching mechanism switches the other side spring clutch to the relaxed state and the one side spring clutch to the tightened state. Therefore, the camshaft rotates in the forward direction in accordance with the positive rotation torque fluctuation, and the rotation of the camshaft beyond the maximum forward rotation is restricted by the stopper mechanism. Here, even if a negative rotation torque fluctuation occurs due to the spring force of the valve spring and the camshaft tries to reverse, the reverse rotation is restricted by the tightening force of the one side spring clutch with respect to the cylindrical body. Therefore, the camshaft is reliably held at 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. Reference numeral 1 denotes a cam bearing 2 which is supported on a cam bearing 2 on an upper portion of a cylinder head and a camshaft (not shown). A driven sprocket, which is provided on the outer periphery of one end 1a of the camshaft 1 and receives a driving force from a drive sprocket of a crankshaft via a timing chain, is a driven sprocket. A stopper mechanism 4 and two spring clutches 5 and 6 are provided between the one end portion 1a and the driven sprocket 3. The intermittent operation of the two spring clutches 5 and 6 is relatively switched by the switching mechanism 7.

More specifically, the camshaft 1
The stepped cylindrical sleeve 8 is fastened and fixed to the one end 1a from the axial direction by a mounting bolt 9. The sleeve 8 includes a cylindrical member 10 fitted to the small-diameter portion and the medium-diameter portion on the distal end side, and a substantially U-shaped cross-section supporting member 12 disposed at the distal end edge of the small-diameter portion by the mounting bolt 9. They are fixed together. A cover member 13 having a large diameter and a substantially U-shaped cross section is fixed to the distal end side of the support member 12 with a bolt 14. Further, the cylindrical member 10 is formed with a locking groove 11 in the axial direction, and as shown in FIGS. 4 and 5, a semicircular notch 15 is formed in the outer peripheral wall on the distal end side at the lower end.

The driven sprocket 3 comprises a cylindrical main body 3a having a stepped cylindrical shape, and a gear 3b provided on an outer periphery of an end of the cylindrical main body 3a and wound with a timing chain. One end on the gear 3b side is a sleeve 8
Is rotatably supported on the outer peripheral surface of the large-diameter portion 8a, and a guide pin 16 is implanted along the radial direction below the other end.

As shown in FIGS. 1 and 3, the stopper mechanism 4 has a projection 17 integrally formed in the end face of the cylindrical body 3a on one end side in the axial direction, and opposes the end face on the one end side. A stopper groove 18 is formed in the large-diameter portion 8a of the sleeve 8 so as to be cut out in an arc shape along the radial direction and the projection 17 is engaged with the stopper groove 18. Both end edges 18a and 18b of the stopper groove 18 are formed by the projection 17 The positions of the cam shaft 1 relative to the sprocket 3 in the maximum positive and negative directions are restricted at positions where the cam shaft 1 abuts on both sides of the cam shaft 1.

The first and second spring clutches 5, 6
Are disposed between the tubular member 10 and the tubular main body 3a, are provided in series in the axial direction, and each outer peripheral edge is disposed close to the inner peripheral surface 3c of the tubular main body 3a. I have.
4 and 5, the first spring clutch 5 on the cover member 13 is wound rightward in the drawing, and the second spring clutch 6 on the one end 1a of the cam shaft is wound in the drawing. It is formed left-handed. Further, the outer ends 5a and 6a of the spring clutches 5 and 6 bent inward are fixed to both ends of the locking groove 11 of the tubular member 10, respectively, while being bent inward. The inner ends 5b and 6b, which are offset from each other in the axial direction, are opposed to each other with a predetermined gap X in the circumferential direction.

The switching mechanism 7 includes a slider 19 having a substantially U-shaped cross section provided slidably in the axial direction between the support member 12 and the cover member 13 and an outer peripheral surface of the cylindrical main body 3a. along provided, FIG. 1 the slider 19
A compression spring 20 for urging in the middle left direction; and a pressure chamber 21 formed between the slider 19 and the cover member 13.
And a hydraulic circuit 22 for introducing a hydraulic pressure into the pressure chamber 21.

The slider 19 is shown in FIGS.
The cover member 1 is attached to the outer peripheral edge of the disk-shaped main body 19a.
3, a flange portion 19b is provided integrally with the inner peripheral surface of the cylindrical portion, and a pair of relatively long locking members 23, 24 project along the camshaft axial direction on the lower inner end surface of the main body 19a. Has been established. The locking members 23 and 24
As shown also in FIG.
9a, a bolt 26 inserted into a bolt hole 25 formed in
Plate-shaped bases 23a, 24 fixed by 26
and a pair of locking shafts 23b, 24b inserted between the gaps X of the spring clutches 5, 6 from the upper end edges of the bases 23a, 24a via the cutouts 15 respectively. The bolt hole 25 is formed in a circular arc shape that 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 24a on one side have an inner diameter set relatively larger than the outer diameter of the shafts of the bolts 26, 26 so that the relative positions of the bases 23a, 24a are relatively large. The span between the locking shafts 23b and 24b can be finely adjusted by shifting the position in the circumferential direction. Further, each locking shaft 23b, 24b
It has a rectangular cross section, and each outer surface is in contact with each inner end 5b, 6b of each spring clutch 5, 6 from the inside. Further, the flange 19b supports the other end of the compression spring 20, one end of which is supported by the step 3c of the cylindrical body 3a, and the lower end of the guide pin as shown in FIG. An inclined long groove 28 into which the 16 is engaged is formed. The long groove 28 rotates the slider 19 forward and backward in a predetermined direction via the guide pin 16 in accordance with the linear axial movement of the entire slider 19. The maximum leftward movement of the slider 19 is
At the step 29 of the support member 12, the movement in the maximum right direction is restricted by the cylindrical member 10.

The hydraulic circuit 22 branches off from the oil main gallery 30 and is formed in a radial direction of the cam bearing 2 and the camshaft 1. The introduction passage 31 extends in the inner central axis direction between the camshaft 1 and the mounting bolt 9. The formed axial passage 32, an oil chamber 33 formed between 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 communicates the oil chamber 33 and the pressure chamber 21.

At the upstream end of the introduction passage 31, there is provided a solenoid valve 37 for introducing and shutting off the hydraulic pressure fed from the oil pump 35 by an output signal from an electronic controller 36.
Is provided. The electronic controller 36 detects the current engine operating state based on output signals from a crank angle sensor, an air flow meter, etc.
9 is ON / OFF controlled.

The operation of this embodiment will be described below.

First, for example, in an engine low load region, an OFF signal (non-energized) is output to the solenoid valve 37 by the electronic controller 36, and the introduction of oil pressure from the oil pump 35 to the pressure chamber 21 is shut off. For this reason, the slider 19
Means that the front end face is supported by the support member 1 by the spring force of the compression spring 20.
It is held at the maximum leftward position (the position in FIG. 1) abutting on the second step portion 29. In such a state, the slider 19 is rotated upward (counterclockwise in FIG. 2) by the guide pin 16 through the long groove 28 as shown by the solid line in FIG.

As a result, the second locking shaft 24b presses the inner end 6b of the second spring clutch 6 counterclockwise as shown in FIG. Therefore, the second spring clutch 6 is entirely deformed into a reduced diameter state against its own spring force, releases the tightening of the cylindrical body 3a to the inner end face 3c, and releases the cylindrical member 10 from the cylindrical 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 expands the inner peripheral surface 3c of the cylindrical main body 3a.
Tighten. Thus, rotation of the cylindrical member 10 in the negative direction (counterclockwise in FIG. 2) with respect to the cylindrical main body 3a is permitted, but rotation in the positive direction is restricted.

Therefore, in this state, when a negative rotational 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 one end 18a of the projection 17 to restrict further rotation. Here, when a positive rotation torque is generated in the camshaft 1 and the camshaft 1 tries to rotate in the clockwise direction (positive direction) in the drawing, the first spring clutch 5 tightens the cylindrical body 3a as described above. By the action, the forward rotation of the camshaft 1 is reliably restricted. Therefore, the camshaft 1 is held at a relative rotation position where free rotation in both the positive and negative directions with respect to the driven sprocket 3 is restricted and the closing timing of the intake valve is delayed.

On the other hand, when the engine has shifted to a high load region,
When the solenoid valve 37 is turned on (energized) and the hydraulic oil pressure-fed 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, the pressure chamber 21 immediately becomes high pressure. Therefore, as shown by the dashed line in FIG. 1, the slider 19 moves to the right in the figure until the bases 23 a and 24 a come into contact with the end surface of the cylindrical body 3 a against the spring force of the compression spring 20. At the same time, the guide pin 16 is rotated downward (clockwise in FIG. 2) by the guide pin 16 through the long groove 28, 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 5b of the first spring clutch 5 in the drawing. Press clockwise. For this reason, contrary to the above, the entire first spring clutch 5 is reduced in diameter to release the tightening to the cylindrical main body 3a, while the second spring clutch 6 expands in diameter by its own spring force and the cylindrical main body 3 The inner peripheral surface 3c of 3a is tightened. Thereby, the rotation of the cylindrical member 10 in the positive direction (clockwise direction in FIG. 2) with respect to the cylindrical main body 3a is permitted, but the rotation in the negative direction is restricted.

Accordingly, the camshaft 1 rotates in the positive direction due to the positive rotation torque fluctuation, and the other end portion 18b of the stopper groove 18 abuts on the projection 17 to further restrict the forward rotation. Here, when a negative rotation torque is generated in the camshaft 1 and the camshaft 1 attempts to rotate in the counterclockwise direction (negative direction), the rotation of the camshaft 1 in the negative direction is reliably restricted by the tightening action of the second spring clutch 6. Is done. Therefore, the camshaft 1 is held at a relative rotation position where free rotation in both 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 increases as the positive and negative rotational torques increase, so that the rotation of the camshaft 1 can be reliably controlled.
Further, the hydraulic oil in the pressure chamber 21 when the load shifts from the high load range to the low load range is quickly discharged to the outside via the electromagnetic valve 37.

Further, in this embodiment, since the relative rotation of the camshaft 1 utilizes the positive and negative rotational torque fluctuations, the switching control of the valve timing in response to the engine operation change becomes possible. Further, the positioning of the locking shafts 23b and 24b with respect to the inner ends 5b and 6b of the spring clutches can be finely adjusted after assembling the components via 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 for example, the switching mechanism 7 can have a different configuration. It is also possible to apply 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 utilizes the fluctuation of the rotational torque of the camshaft instead of the conventional cylindrical gear. As a result, it is possible to improve the efficiency of manufacturing and processing operations.

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

[Brief description of the drawings]

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

FIG. 2 is a view taken in the direction of arrow B in FIG. 1;

FIG. 3 is a view taken in the direction of the arrow C in FIG. 1;

FIG. 4 is a sectional view taken along line DD of FIG. 1;

FIG. 5 is a sectional view taken along line EE of FIG. 1;

FIG. 6 is a sectional view taken along line FF of FIG. 1;

FIG. 7 is a sectional view taken along line GG of FIG. 1;

[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.

Continuation of the front page (72) Inventor Yoshiharu Kitamura 1170, Ako, Komagane-shi, Nagano Japan 3 Within Hatsu Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) F01L 1/34

Claims (1)

(57) [Claims] 1. A valve timing control device for variably controlling the opening / closing timing of a valve by rotating a rotating body, which is rotationally driven by a driving force of an engine, and a camshaft, to which a rotating force is transmitted from the rotating body, in forward and reverse directions. And a stopper mechanism provided between the rotating body and the camshaft to restrict the forward / reverse maximum relative rotation of the two, and an axial direction along an inner peripheral surface of a cylindrical main body of the rotating body. A pair of spring clutches arranged in series with each other and wound in opposite directions to each other; outer ends of both spring clutches respectively fixed to the camshaft; and two spring clutches provided to face each other No
A switching mechanism for selectively pressing one of the ends in the circumferential direction to switch the cylindrical body to a relaxed or tightened state, wherein the one end of the sprag whose inner end is pressed by the switching mechanism is provided.
A ring clutch relaxes the cylindrical main body so that the cylindrical main body can be loosened.
While allowing forward and reverse rotation, the other end of which the inner end is not pressed
A spring clutch tightens the inner peripheral surface of the cylindrical body.
Rotating the rotating body and the camshaft
A valve timing control device for an internal combustion engine, characterized in that the valve timing control device is configured to restrict the anti-rotation .