PHASE CHANGING DEVICE FOR AUTOMOBILE ENGINE

TECHNICAL FIELD

The present invention is directed to a phase changing device for varying opening-closing timing of valves of an automobile engine by means of a torque means for providing the rotary drum of the engine with a torque to vary the rotational phase of the camshaft relative to a sprocket of the engine.

BACKGROUND ART

There has been known a valve timing control device of this type, as disclosed in Patent Document 1 cited below. In the device of the Patent Document 1 a drive plate 3 driven by the crankshaft of the engine is assembled such that the drive plate 3 is rotatable relative to a flange ring 7 coupled to the camshaft 1 of the device. Integrally mounted to the camshaft 1, ahead of the drive plate 3, are a lever shaft 10 having three levers 9 and a hold ring 12, which are securely fixed to the flange ring 7 with a bolt 13. Rotatably mounted on the hold ring 12 via a thrust bearing 28 is a middle rotor 23 ahead of the lever shaft 10.

A link 14 is rotatably connected at one end thereof to each of the three levers 9 with a pin 15. Formed at the other end of the link is an axial receptacle hole 16 for receiving therein movable member 17. Formed in the front end of the drive plate 3 is a radial slot 8 (serving as a radial guide). Formed on the rear end of the middle rotor 23 are three spiral slots 24 each spiraling in the direction of rotation of the drive plate 3 with decreasing radius. The movable member 17 are provided at three positions in association with the three corresponding spiral slots 24. Each of the movable member 17 has retainers 19 and 21 for rotatably holding balls 18 and 20 in the respective radial slot 8 and spiral slot 24 via a leaf spring 22.

Provided on the front end of the middle rotor 23 is a permanent magnet block 29 having N- and S-poles that alternates along the circumference of the rotor 23. Arranged in front of the permanent magnet block 29 is a yoke block 30 having first pole tooth ring 37 and second pole tooth ring 38 for generating different magnetic poles when electromagnetic coils 33A and 33B are energized. The magnetic poles of the pole tooth rings 37 and 38 are switched on and off in a given switching pattern by the middle rotor 23 so as to apply changing magnetic forces on the permanent magnet block 29 to rotate the drive plate 3 relative to the camshaft 1. The rotation of the drive plate 3 is terminated by ending switching of the polarities.

As the middle rotor 23 is angularly advanced than the drive plate 3 in the rotational direction R (referred to as angularly advancing direction) under the polarity switching of the polar tooth rings 37 and 38, the balls 18 and 20 of the movable member 17 are displaced radially outwardly in the respective radial slot 8 and spiral slot 24. Then, the lever shaft 10 is retarded than the drive plate 3, that is, rotated in the angularly retarding direction (opposite to the rotational direction R of the drive plate 3), thereby rendering the rotational phase of the crankshaft and camshaft 1 retarded in the angularly retarding direction. On the other hand, when the polarity switching pattern of the polar tooth rings 37 and 38 is changed so as to delay the middle rotor 23 in the angularly retarding direction, the movable member 17 is displaced radially inwardly, thereby rendering the rotational phase of the crankshaft and camshaft changed in the angularly advancing direction.

During operation, the camshaft 1 is subjected to reactions of the valve springs, which reaction cause disturbing torques on the camshaft. Such disturbing torques may cause unexpected angular displacements of the drive plate 3 relative to the camshaft 1. The device of the Patent Document 1 has a self-lock mechanism in which the camshaft 1 is immovably locked to the drive plate 3 via the link 14 and lever 9 by pushing the ball 20 in the direction perpendicular to the spiral slot 24 against the inner wall of the spiral slot 24 when a disturbing torque occurring in the camshaft 1 is transferred to the movable member 17 via the lever 9 and link 14 causing the ball 18 to be displaced in the radial slot 8 in the direction perpendicular to the spiral slot 24.

DISCLOSURE OF THE INVENTION
Objects of the Invention

The prior art device suffers a problem that, in the event of such a torque disturbance as mentioned above, the ball 20 collide the inner wall of the spiral slot 24 located on either outward or inward side of the radial groove 8, when each ball makes point contact with the wall and applies a large pressure on a localized small area of the spiral slot 24. This is a source of frictional wear of the spiral slot and causes eventual backlashes in the ball-groove system.

A further problem is that under the disturbing torque the balls 18 and 20 can generate axial thrusts in the camshaft 1 via the retainers 19 and 21, radial slot 8, and spiral slot 24, which may cause an axial backlash of the link 14.

A still further problem is that it is difficult to provide a large phase angle variation between the camshaft 1 and the drive plate 3 in the structurally complex link mechanism 14 of the prior art device.

The present invention overcomes such prior art problems as mentioned above by providing a phase changing device for use with an automobile engine, the device having a self-lock mechanism in which phase varying members play roles of the prior art balls 18 and 20 without generating localized pressure on one side of the inner circumferential walls of the groove guides as they are displaced in the groove guides, thereby preventing frictional wear of the inner circumferential walls of the groove guides and avoiding generation of such axial thrusts as mentioned above. In this device a large phase angle variation can be realized between the camshaft 1 and the drive plate 3.

Means for Solving the Problems

To achieve these objects the invention provides a phase changing device as defined in Claim 1 which has: a drive rotor driven by the crankshaft of an engine, a middle rotor integral with the camshaft of the device and arranged ahead of the drive rotor, a control rotor arranged ahead of the middle rotor and rotatable about the rotational axis common to the drive rotor and the middle rotor, the device capable of altering the relative phase angle between the drive rotor and the camshaft by rotating the middle rotor relative to the drive rotor by providing the control rotor with a torque generated by a torque means, the device characterized by comprising:

curved first guide grooves formed in the control rotor, each groove skewed with respect to a circumference of a circle centered at the rotational axis;

oblique guide grooves each groove formed in the middle rotor and extending at an angle with respect to a radius crossing the groove;

second guide grooves formed in the drive rotor and skewed with respect to the circumference of a circle centered at the rotational axis of the drive rotor,

block sections each extending along, and movable in, the respective first guide;

first slide members each protruding from the respective block section for engagement with, and movement in, the respective skewed guide groove; and

phase varying members each having a second slide member that extends through an escape groove formed in the middle rotor and engages the respective second guide groove so as to move in the second guide groove.

When subjected to brake action of the torque means, the control rotor is retarded in phase angle relative to the middle rotor. The phase varying members move radially on the control rotor as the block sections are displaced in the curved first guide grooves skewed with respect to the circumference. As the first slide members of the phase varying members are displaced in the respective oblique guide grooves and the second slide members are displaced radially in the respective second guide grooves, the middle rotor integrated to the camshaft rotates relative to the drive rotor in a manner defined by the configuration of the second guide grooves, thereby varying the phase angle between the camshaft and the drive rotor driven by the crankshaft.

The inventive device as defined in claim 1 is provided with a self-lock mechanism adapted to immovably lock the phase varying members, should torque disturbance occur in the camshaft movement caused by reaction of the valve springs, thereby prohibiting relative rotational motion of the middle rotor and the drive rotor to prevent unexpected phase variation between the camshaft and the drive rotor driven by the crankshaft.

(Function)

In other words, if such torque disturbance takes place, the middle rotor coupled to the camshaft is acted upon by a torque that causes the middle rotor to rotate relative to the drive rotor. In that event, the first slide members are acted upon by forces transferred from the engaging oblique guide grooves in radially inward directions, and the second slide members are acted upon by forces transferred from the second guide grooves in the substantially opposite directions. The block sections of the phase varying members are acted upon by radial forces from the first and second slide members in the radially opposite directions. These forces skew the phase varying members in the engaging first guide grooves and force them against the opposite inner walls of the first guide grooves, resulting in frictional forces acting on the block sections from the opposite sides to immovably fix the phase varying members in position in the first guide grooves.

In this case, the first and second slide members protruding from the block sections are also immovably fixed relative to the engaging oblique guide grooves and second guide grooves. Thus, the middle rotor coupled to the camshaft is immovably fixed relative to the drive rotor, thereby preventing unanticipated phase variation that could otherwise occur between the camshaft and the drive rotor driven by the crankshaft.

That is, should such torque disturbance take place, the phase varying members generate frictional forces via the block sections acting on the both sides of the first guide grooves, so that frictional forces are not localized but distributed over different areas of the grooves.

Further, since the block sections are not spherical in shape, the block sections will not generate forces in response to the torque disturbance that thrust the respective rotors in the axial direction.

The inventive device as defined in claim 2 provides the first and second slide members in the form of a shaft-like member that can roll in the respective first and second guide grooves.

(Function)

By providing the first and second slide members in the form of rollable shaft-like members, less frictional forces are generated on the wall of the oblique guide grooves and the second guide grooves. In addition, disturbing torques are transferred to the block sections without being damped by the sliding friction of the first and second slide members.

RESULTS OF THE INVENTION

The invention defined in Claim 1 will generate little local frictions with the phase varying members in contact with the first guide grooves, thereby reducing the wear of the contact areas thereof and cluttering of the members.

Less axial thrusts will be generated, and hence generating reduced axial cluttering of the mechanism.

It should be noted that the phase variation mechanism can be obtained in a simple combination of phase varying members and guide grooves. In addition, a large phase variation angle can be realized by providing sufficiently long first guide grooves.

The invention defined in Claim 2 will generate little friction with the first and second slide members in sliding contact with the oblique and second guide grooves, thereby reducing axial cluttering of the mechanism. In addition, since disturbing torques are transferred positively to the block sections without being damped by the sliding frictions of the first and second slide members, the block sections of the first guide grooves can be infallibly locked.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a phase changing device for use with an automobile engine in accordance with a first embodiment of the invention, the view taken from front.

FIG. 2 is an exploded perspective view of the device taken from behind.

FIG. 3 is a front view of the device.

FIG. 4 is an axial cross section of the device taken along Line A-A of FIG. 3.

FIG. 5 is a diagram illustrating phase varying members, and more particularly, FIG. 5(a) is a perspective view and FIG. 5(b) is an exploded perspective view.

FIG. 6 is a diagram showing the arrangement of guide grooves and phase varying members in accordance the first embodiment in which the device is adapted to perform phase angle variation in angle retardation mode.

FIG. 7 is a vertical cross section of a control rotor of the device, taken along Line B-B of FIG. 4.

FIG. 8 is a cross section of a middle rotor taken along Line C-C of FIG. 4.

FIG. 9 is a cross section of a drive rotor of the device taken along Line D-D of FIG. 4.

FIG. 10 is a cross section of a phase variation stopper of the device taken along Line E-E of FIG. 4.

FIG. 11 is a diagram illustrating the self-lock mechanism of the first embodiment, FIG. 11(a)-(c) showing its phase varying members acted upon by forces generated in cam torque disturbance.

FIG. 12 is a diagram illustrating an arrangement (referred to as phase advancing arrangement) for performing phase variation in the angularly advancing direction. More particularly, FIG. 12(a) shows the initial arrangement of the guide grooves and phase varying members of the respective rotors; FIGS. 12(c) and (d) the phase varying members acted upon by external forces caused by a cam torque disturbance.

FIG. 13 is an exploded perspective view of the phase changing device in accordance with a second embodiment of the invention for use with an automobile engine.

FIG. 14 is an axial cross section of the device of the second embodiment of the invention.

FIG. 15 is a cross section of a mechanism for performing relative rotation of the control rotor and the second control rotor, taken along Line F-F of FIG. 14.

FIG. 16 is an exploded perspective view of the phase changing device for use with an automobile engine in accordance with a third embodiment of the invention, the view taken from front.

FIG. 17 is an axial cross section of the device in accordance with the third embodiment of the invention.

FIG. 18(
a) shows a transverse cross section of the second control rotor taken along Line G-G of FIG. 17; FIG. 18(a), transverse cross section of the second control rotor taken along Line H-H of FIG. 17; FIG. 18(c), a transverse cross section of the second control rotor taken along Line I-I of FIG. 17.

FIG. 19 shows an device of the third embodiment in operation. More particularly, FIG. 19(a)-(c) respectively show the initial condition prior to a phase variation, a condition during a phase variation, and after a maximum phase variation;

FIG. 20 is an exploded perspective view of a phase changing device for use with an automobile engine in accordance with a fourth embodiment of the invention, the view taken from front.

FIG. 21 is an exploded perspective view of the device, the view taken from behind.

FIG. 22 is an axial cross section of the device in accordance with the fourth embodiment of the invention.

FIG. 23(
a) shows a transverse cross section of a circular eccentric cam of a second control rotor, taken along Line J-J of FIG. 22; FIG. 23(b), a cross section of a cam guide plate taken along Line K-K of FIG. 22; and FIG. 23(c), a cross section of a circular eccentric cam of a control rotor, taken along Line L-L of FIG. 22.

FIG. 24 is a diagram illustrating the fourth device in operation, and more particularly, FIG. 24(a)-(c) respectively show conditions of the device prior to a phase variation, during a phase variation; and after a maximum phase variation

SYMBOLS

- 40: camshaft
- 41: drive rotor
- 43: middle rotor
- 44: electromagnetic clutch (torque means)
- 45: control rotor
- 46: sprocket (drive rotor)
- 47: drive plate (drive rotor)
- 49 and 49′: oblique guide grooves
- 50: escape groove
- 51: first guide groove
- 52 and 52′: second guide grooves
- 54: torsion spring
- 57: phase varying members
- 58: block sections
- 59: first slide members
- 60: second slide members
- 67, 72, and 81: second electromagnetic clutches (torque means)
- L1: rotational axis

BEST MODE FOR CARRYING OUT THE INVENTION

The invention will now be described in detail by way of example with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view of a phase changing device for use with an automobile engine in accordance with a first embodiment of the invention, the view taken from front; FIG. 2 is an exploded perspective view of the device taken from behind; FIG. 3 is a front view of the device FIG. 4 is an axial cross section of the device taken along Line A-A of FIG. 3; FIG. 5(a) is a perspective view and FIG. 5(b) is an exploded perspective view of phase varying members; FIG. 6 is a diagram showing the initial arrangement of the guide grooves and phase varying members of respective rotors for performing phase angle variation in angle retardation mode in accordance with the first embodiment of the invention; FIG. 7 is a vertical cross section of a rotational control body of the device; FIG. 8 is a cross section of a middle rotor taken along Line C-C of FIG. 4; FIG. 9 is a vertical cross section of a rotational driving body of the device taken along Line D-D of FIG. 4; FIG. 10 is a cross section of a phase varying stopper of the device taken along Line E-E of FIG. 4; FIG. 11(a)-(c) show a self-lock mechanism of the first embodiment; FIG. 12(a)-(c) show an arrangement of phase changing device for angularly advancing direction; FIG. 13 is an exploded perspective view of the phase changing device in accordance with a second embodiment of the invention for use with an automobile engine; FIG. 14 is an axial cross section of the device in accordance with the second embodiment of the invention; FIG. 15 is a cross section of a relative-rotation-mechanism for the rotational control body and the second rotational control body; FIG. 16 is an exploded perspective view of the phase changing device for use with an automobile engine in accordance with a third embodiment of the invention; FIG. 17 is an axial cross section of the device in accordance with the third embodiment of the invention; FIG. 18(a) is a transverse cross section of the second rotational control body taken along Line G-G of FIG. 17; FIG. 18(b) is a transverse cross section of the second rotational control body taken along Line H-H of FIG. 17; FIG. 18(c) a transverse cross section of the second rotational control body taken along Line I-I of FIG. 17; FIG. 19 is a diagram showing the device in operation, and more particularly, FIG. 19(a)-(c) respectively show the initial condition prior to a phase variation, a condition during a phase variation, and after a maximum phase variation; FIG. 20 is an exploded perspective view of a phase changing device for use with an automobile engine in accordance with a fourth embodiment of the invention; FIG. 21 is an exploded perspective view of the device as viewed from behind FIG. 22 is an axial cross section of the device in accordance with the fourth embodiment of the invention; FIG. 23(a) shows a transverse cross section of a circular eccentric cam of a second rotational control body, taken along Line J-J of FIG. 22; FIG. 23(b), a cross section of a cam guide plate taken along Line L-L of FIG. 22; and FIG. 23(c), a cross section of a circular eccentric cam of the rotational control body, taken along Line L-L of FIG. 22; and FIG. 24 is a diagram illustrating the fourth device in operation, and more particularly, FIG. 24(a)-(c) respectively show the initial condition of the device prior to phase variation, during a phase variation, and after a maximum phase variation.

Phase changing devices shown in these figures are in accord with either one of the first through fourth embodiments of the invention. The device is integrally assembled to an engine such that the rotation of the crankshaft is transmitted to the camshaft to synchronize opening-closing of the air suction/exhaustion valves with the rotational motion of the crankshaft of the engine, and vary the opening-closing timing in accord with the load and/or rpm of the engine.

Referring to FIGS. 1 through 4, there is shown an device of embodiment 1, which comprises a drive rotor 41 integrally formed of a sprocket member 46 driven by the crankshaft (not shown) and a drive plate 47. The drive rotor 41 is rotatably mounted on a center shaft 42 which is integrated to the camshaft 40 of the device. A middle rotor 43 is immovably fixed, ahead of the drive rotor 41, to the center shaft 42. A control rotor 45 is rotatably mounted on the front end of the center shaft 42 and adapted to be controlled by an electromagnetic clutch 44. The drive rotor 41, middle rotor 43, and control rotor 45 are coaxial about the axis L1.

The leading end 40a of the camshaft 40 is securely fixed in the circular hole 42a of the center shaft 42. Cylindrical sections 42c and 42d, formed before and after a pair of flange-shaped stopper protrusion 42b provided on the outer surface of the center shaft 42, are rotatably fitted in the circular holes 46c and 47a of the sprocket member 46 and of a drive plate 47, respectively, to rotatably support the sprocket member 46 and drive plate 47. The sprocket member 46 has sprockets 46a and 46b. The sprocket member 46 and the drive plate 47 are integrally coupled with a multiplicity of coupling pins 48 to form a drive rotor 41.

The drive plate 47 is provided with a pair of curved second guide grooves 52. A central circular hole 47a is formed in the drive plate 47. In the first embodiment, the second guide grooves 52 are elongate grooves extending in the counterclockwise direction (as viewed from the front) and curving radially inwardly so that the radius of the groove from the rotational axis L1 decreases continuously.

Formed in the disk shaped middle rotor 43 are a square axial through hole 43, a pair of oblique guide grooves 49 skewed in the direction from an upper right side to a lower left side of the radius crossing the grooves as viewed from before backward, and escape holes 50 each running in parallel to the respective oblique guide grooves. The middle rotor 43 is securely fixed to the center shaft 42 by fitting the flat engaging face 42j of the center shaft 42 in the square hole 43a of the middle rotor 43.

The control rotor 45 has a central circular hole 45a and a pair of curved first guide grooves 51. In the first embodiment, the first guide grooves 51 are elongate grooves extending in the clockwise direction (as viewed from front) and curving radially inwardly, so that the radii of the grooves from the central axis L1 decrease continuously. The drive rotor 45 is rotatably mounted on the cylindrical section 42e provided on the leading end of the center shaft 42 via a thrust bearing 53 mounted in a recessed circular bore 45d formed in the front end of the circular hole 45a.

Mounted on an engine casing (not shown) at a position ahead of the control rotor 45 is an electromagnetic clutch 44 for attracting the control rotor 45 when a coil 44a is energized. Inside the electromagnetic clutch 44 is a spring holder 55 having on the outer circumference thereof a torsion spring 54. The leading end 55a of the torsion spring 54 is hooked in the recess 42f formed in the center shaft 42. The spring holder 55, center shaft 42, and camshaft 40 are coupled integrally by passing a bolt 56 through central holes 55b and 42g of the spring holder 55 and center shaft 42, respectively, and tightly screwing the bolt 56 into a threaded female bore 40b formed in the camshaft 40. Thus, the spring holder 55 and center shaft 42 are rotated together with the camshaft. The opposite ends 54a and 54b of the torsion spring 54 are securely fixed in the bore 45b formed in the control rotor 45 and in the bore 55c of the spring holder 55 to urge the control rotor 45 in the direction opposite to the rotational direction of the drive rotor 41 against the control torque provided by the electromagnetic clutch 44.

Each of the phase varying members 57 has a block section 58, a first slide member 59, and a second slide member 60 as shown in FIG. 5. The block sections 58, first slide members 59, and second slide members 60 of the phase variation members 57 respectively engage the first guide grooves 51, oblique guide grooves 49, and second guide grooves 52, as shown in FIG. 6 (escape hole 50 not shown). Each of the block sections 58 is a generally oblong member having a convex surface 58a of the same curvature as the radially outward circumference 51a of the first guide groove 51 and a second concave surface 58b of the same curvature as the radially inward circumference 51b of the first guide groove 51, so that the block section 58 can freely move in the first guide groove 51.

Each of the first slide member 59 has a coupling shaft 59a fitted in the circular bore 58c of the block section 58 and a slide shaft 59b engaging the oblique guide groove 49 for movement therein. Each of the second slide member 60 has a coupling shaft 60a fitted in the circular bore 58d of the block section 58 and a slide shaft 60b movable in the second guide groove 52. The coupling shaft 60a has a smaller outer diameter than the width of the escape hole 50 and passing through the escape hole 50 without touching it.

It is preferred to securely fix the coupling shafts 59a and 60a in the respective circular bores 58c and 58d, or rotatably mount the slide shafts 59b and 60b on the coupling shafts 59a and 60a that are securely fitted in the respective circular bores 58c and 58d, thereby making the slide shafts 59b and 60b slidable in the oblique guide grooves and the second guide grooves 52. In this configuration, these shafts can move smoothly in the guide grooves 49 and 52, thereby reducing wear of the slide shafts 59b and 60b. Preferably, the slide shaft 59b and 60b are rollable in the guide grooves 49 and 52. Alternatively, however, they can be fixed in the circular holes 58c and 58d together with the coupling shafts 59a and 60a but slidable in the guide grooves 49 and 52.

Referring to FIGS. 6 through 10, there is shown the device of the first embodiment in phase varying operation. In the first embodiment, the device can operate in phase angle retardation mode in which the middle rotor 43 is rotated in the counterclockwise direction D2 from the initial delay-free position to delay the phase angle of the middle rotor 43 coupled to the camshaft 40 relative to the drive rotor 41 in rotation in the clockwise direction D1 as viewed from front. The phase varying members 57 engaging the first guide grooves 51, oblique guide grooves 49, and second guide grooves 52 are initially located at the most radially outward positions possible, as shown in FIG. 6. Under the initial condition, the control rotor 45 is urged in the clockwise direction by the torque supplied by the torsion spring 54, and the middle rotor 43 and control rotor 45 rotate in the direction D1 together with the drive rotor 41 since the phase varying members 57 are immovably fixed.

As the electromagnetic clutch 44 is energized, the control rotor 45 shown in FIG. 7 is attracted to the electromagnetic clutch 44 and abuts on the frictional members 61 (FIG. 4), when the control rotor 45 begins to rotate in the counterclockwise direction D2 relative to the drive rotor 41 and middle rotor 43. In this case, the block sections 58 of FIG. 6 tend to rotate in the clockwise direction D1 in the first guide grooves 51, which causes the phase varying members 57 to shift as a whole in the radially inward direction D3, thereby decreasing the distance between the rotational axis L1 and the grooves 51.

As shown in FIG. 8, each of the oblique guide grooves 49 is skewed through an angle of δ with reference to Line L2 connecting the rotational axis L1 and the respective axes of the first slide shafts 59b in the angularly advancing direction (that is, in the clockwise direction D1) relative to the drive rotor 41. The first slide shafts 59b, in engagement with the oblique guide grooves 49, are displaced in the grooves 49 in the radially inward direction D3.

When displaced in the radially inward direction D3, the second slide shafts 60b shown in FIG. 9 are also displaced in the counterclockwise direction D2 in the second guide grooves 52. Then, the middle rotor 43 is angularly delayed (or rotated) relative to the drive rotor 41 in accord with the displacements of the second slide shafts 60b in the second guide grooves 52. As a consequence, the phase angle of the camshaft 40 integral with the middle rotor 43 relative to the drive rotor 41 driven by the crankshaft is changed in the angularly delaying direction (that is, counterclockwise direction D2).

It is noted that the angular delay of the middle rotor 43 relative to the drive rotor 41 increases until the torque of coil spring 54 balances the torque of the electromagnetic clutch 44. The maximum angular delay corresponds to the displacement of the second slide shaft 60b from one end of the second guide groove 52 to the other end.

On the other hand, if the electric current through the electromagnetic clutch 44 is reduced to weaken the braking power of the control rotor 45, the control rotor 45 shown in FIG. 7 is rotated backward by the torque of the spring 54 in the clockwise direction D1 relative to the middle rotor 43, which in turn causes the phase varying member 57 to move radially outwardly (in the direction opposite to D3).

In this case, the guide grooves 49 are acted upon by forces from the first slide shafts 59b sliding in the oblique guide grooves 49, and the grooves 52 from the second slide shafts 60b moving in the second guide grooves 52 in the clockwise direction D1. Accordingly, the middle rotor 43 is rotated in the angularly advancing direction (or clockwise direction D1) relative to the drive rotor 41 rotated by the crankshaft, thereby restoring possibly the initial maximum phase angle between the camshaft 40 and the drive rotor 41.

Incidentally, as shown in FIG. 10, a pair of stopper protrusions 42b formed on the center shaft 42 engage the stopper recess 47a formed in the drive plate 47. When the block sections 58, first slide shafts 59b, and second slide shafts 60b assume their initial positions prior to any phase variation or positions at the maximum phase variation, the tips 42b1 and 42b2 of the stopper protrusions 42b touch respective end portions 47a1 and 47a2 of the respective stopper recesses 47a to serve as stoppers. Thus, they prevent the block sections 58, first slide shafts 59b, and second slide shafts 60b from directly colliding the respective first guide grooves 51, oblique guide grooves 49, and second guide grooves 52, thereby relieving their collision impact.

Referring to FIG. 11, there is shown a self-lock mechanism for preventing the relative phase angle of the middle rotor 43 relative to the drive rotor from being changed if the middle rotor 43 is subjected to an abrupt disturbing torque from the camshaft 40. In the event that the middle rotor 43 in rotation in the clockwise direction D1 together with the drive rotor 41 and control rotor 45 is subjected to a disturbing torque from a valve spring in the counterclockwise direction D2 via the camshaft 40, as shown in FIG. 11(a), the oblique guide grooves 49 of the middle rotor 43 tend to rotate in the direction D2 relative to the drive rotor 41 and the control rotor 45.

Since the oblique guide grooves 49 are skewed by angle δ in the clockwise direction with respect to Line L2 connecting the rotational axis L1 and the respective axis of the first slide shafts 59b, if the first slide shafts 59b are subjected to such disturbing torque from the oblique guide grooves 49 in the direction D2, the torque exerts forces on the first slide shafts 59b in the radially outward directions F1.

On the other hand, the second slide shafts 60b are acted upon by forces in the counterclockwise direction D2 via the first slide shafts 59b and the block sections 58 coupled thereto. However, since the first slide shafts 59b engage the second guide groove 52 which are curved radially inwardly, the second slide shafts 60b are moved in the radially inward direction in the second guide grooves 52, rather than along the circumference of the drive rotor 41.

As a consequence, the block section 58 is directed in the counterclockwise direction D4 by the radially outward components of the forces F1 acting on the first slide shafts 59b and by the radially inward components of the forces F2 acting on the second slide shafts 60b, as shown in FIG. 11(c). Thus, the convex surfaces 58a of the block sections 58 are forced against the radially outward circumferences 51a of the first guide grooves 51 near the respective first slide shafts 59b. Further, the concave surfaces 58b are forced against the radially inward circumferences 51b of the first slide grooves 51 near the second slide shafts 60b. As a result, frictions take place on both of the radially inward and outward circumferences of the first guide grooves 51, rendering the block sections 58 immovably locked in the respective first guide grooves 51.

Contrary to the foregoing case, in the event that the middle rotor 43 is urged in the angularly advancing direction D1 relative to the drive rotor 41 and control rotor 45 by a disturbing clockwise torque transferred from the camshaft 40, the first slide shafts 59b are acted upon by radially inward forces and the second slide shafts 60b are acted upon by radially outward forces. As a consequence, the block sections 58 are deflected in the opposite clockwise direction D4, thereby generating frictions on both the radially inward and outward sides of the circumference of the first guide grooves 51, which causes the middle rotor 43 to be immovably locked in the first guide groove 51.

As described above, if a disturbing torque is inputted to the middle rotor 43 from the camshaft 40 shown in FIG. 1, the phase varying members 57 are immovably locked and so is the middle rotor 43 relative to the drive rotor 41, thereby keeping the relative phase angle between them unchanged. It should be noted that in this case the locking frictional forces are distributed over the radially inward and outward circumferences 51a and 51b of the first guide grooves 51, frictional wear of the guide grooves 51 and phase varying members 57 is reduced.

Next, referring to FIGS. 12(a)-(c), there is shown the arrangements of the guide grooves 51, 49′, and 52′ of the respective rotors and of the phase varying members 57 for a case where the middle rotor 43 has initially no angular displacement relative to the drive rotor 41 but will be advanced in the angularly advancing direction as needed. Their operations will now be described below.

As shown in FIG. 12(a), the oblique guide grooves 49′ of this phase changing device are skewed through an angle of δ towards the angularly delaying direction (that is, in the opposite counterclockwise direction D2 in contrast to the first embodiment) with reference to the Lines L2 connecting the rotational axis L1 and the respective axes of the first slide shafts 59b. The configuration of this phase changing device is the same as that of the foregoing device for performing phase angle variation in angle retardation mode, except that the second guide grooves 52′ extend in the clockwise direction D1 (opposite to the direction of the first embodiment).

When a brake is applied to the control rotor 45, the block sections 58 are displaced in the first guide grooves 51 to move the phase varying members 57 in the radially inward direction D5 as shown in FIG. 12(a). In this case, the first slide shafts 59b are displaced in the respective oblique guide grooves 49′, and the second slide shaft 60b are displaced in the clockwise direction D1 and in the radially inward direction D5. As a consequence, the first slide shafts 59b and second slide shafts 60b are acted upon by forces from the respective oblique guide grooves 49 and the second guide grooves 52′, which causes the middle rotor 43 having the groove 49′ to be rotated in the angularly advancing clockwise direction D1 relative to the drive rotor 41, and hence advancing the phase angle of the camshaft 40 relative to the drive rotor 41. If the braking on the control rotor 45 is reduced, the phase angle of the camshaft 40 is retarded relative to the drive rotor 41 by the backward torque of the torsion spring 54.

In the event that oblique guide grooves 49′ of the middle rotor 43 are urged to move in the counterclockwise direction D2 relative to the drive rotor and the control rotor 45 by a disturbing torque transferred from the camshaft 40, the first slide shafts 59b are acted upon by forces F3 in the radially outward directions, since each of the oblique guide grooves 49′ is skewed by the angle δ with respect to Line L1 that connects the axis L1 and the axis of the first slide shaft 59b. On the other hand, in response to the forces F3, the second slide shafts 60b are pulled radially inwardly (that is, along the curved second guide groove 52) by the block sections 58 coupled thereto (by forces F4 say as shown in FIG. 12) rather than pulled in the circumferential direction of the drive rotor 41.

As a consequence, the motions of the block sections 58 are deflected in the counterclockwise direction D6 by the radially outward component of the forces F3 acting on the first slide shafts 59b and the radially inward components of the forces F4 acting on the second slide shafts 60b, as shown in FIG. 12(c). On the other hand, in the event that the middle rotor 43 is acted upon by a torque that urges the camshaft 40 to rotate in the angularly advancing direction D1 relative to the drive rotor and control rotor 45, the motions of the block sections 58 are deflected not in the counterclockwise direction D6 but in the opposite clockwise direction. As a consequence, the block sections 58 generate frictional forces between themselves and the radially inward and outward circumferences (52a and 512b) of the first guide grooves 51, which causes the phase varying members 57 to be immovably locked, thereby causing the middle rotor 43 to be immovably locked relative to the drive rotor.

Next, referring to FIGS. 13 through 15, there is shown a phase changing device for use with an automobile engine in accordance with the second embodiment of the invention. In the second embodiment, a second electromagnetic clutch mechanism 62 is employed to restore phase angle in place of the coil spring 54 used in a phase angle restoration mechanism in the first embodiment. This mechanism makes it possible to provide phase variation in the opposite direction as compared with the first electromagnetic clutch 44.

The second electromagnetic clutch mechanism 62 of the second embodiment includes: a second control rotor 63 arranged ahead of the control rotor 45, a multiplicity of planet gears 64 in engagement with a gear 63a that protrudes backward from the second control rotor 63 and with a gear 45c provided in the circular hole formed in the front end of the control rotor 45, a thrust bearing 65, a spring holder 66, and a second electromagnetic clutch 67. The control rotor 45 is rotatably supported on the cylindrical section 42l of the center shaft 42 by rotatably fitting the cylindrical section 42l in the circular hole 45a of the control rotor 45. The second control rotor 63 is rotatably mounted on the leading end of the center shaft 42 by securely fixing the small cylindrical section 42h of the center shaft 42 in the circular hole 65a of the thrust bearing 65 fitted in the recessed circular hole 63b of the second control rotor 63.

The control rotor 45 and second control rotor 63 are spaced apart in the axial direction. The spring holder 66 is fitted on the step section 42i formed at the leading end of the center shaft 42. A bolt 56 is tightly screwed in the threaded bore 40b of the camshaft 40 to prevent the constituent elements 16 of the second control rotor 63 and the like from coming off. The electromagnetic clutch 67 is secured on the engine casing (not shown) facing the second control rotor 63. The second embodiment are the same as the first embodiment in other respects.

Under the initial condition where there is no phase variation, the second control rotor 63 rotates in the clockwise direction D1 together with the control rotor 45 and drive rotor 41. If the electromagnetic clutch 44 is energized to vary the phase angle of the middle rotor 43 relative to the drive rotor, braking action of the electromagnetic clutch 44 takes place, so that the control rotor 45 rotates in the counterclockwise direction D2 relative to the middle rotor 43 which is in rotation in the clockwise direction D1, and the phase varying members 57 are moved radially inwardly. Thus, the phase angle of the middle rotor 43 is changed in the angularly delaying direction (counterclockwise direction D2) relative to the drive rotor 41, as in the first embodiment.

On the other hand, if the second electromagnetic clutch 67 is energized, the second control rotor 63 is rotated in the counterclockwise direction D2 relative to the control rotor 45 rotating in the clockwise direction D1. In this case, the control rotor 45 rotates in the clockwise direction D1 relative to the middle rotor 43 due to the counterclockwise rotation (in the direction D7) of the planet gears 64 between the gears 64a and 45c. As a result, the phase varying member 57 is moved radially outwardly, causing the phase angle of the middle rotor 43 to be advanced (in the clockwise direction D1) relative to the drive rotor 41, as in the first embodiment.

Referring to FIGS. 16 through 19, there is shown a phase changing device in accord with the third embodiment of the invention. The third embodiment is a modification of the second embodiment, in which two electromagnetic clutches are used as in the second embodiment, one for the phase varying mechanism and another for the phase angle varying mechanism. In addition, the planet gears of the phase angle restoration mechanism used in the second embodiment are replaced with slide pins.

Third embodiment includes a second middle rotor 68, second control rotor 69, thrust bearing 70, spring holder 71, electromagnetic clutch 44, and second electromagnetic clutch 72, all arrange ahead of the control rotor 45 in the order mentioned.

As shown in FIG. 18(a)-(c), the control rotor 45 has a central circular hole 45a and a pair of third curved guide grooves 73 formed in the front end thereof, each extending in the clockwise direction D1 about the rotational axis L1 and having a continuously decreasing radius. The second middle rotor 68 has a central square hole 62a and a pair of radial guide grooves 74 formed on the opposite sides of the second middle rotor 68. The second control rotor 69 has a central circular hole 69a, a recessed central circular bore 69b formed in the front end thereof, and a pair of fourth curved guide grooves 75 formed in the rear end thereof each extending in the counter clockwise direction D2 about the rotational axis L1 and having a continuously decreasing radius.

The control rotor 45 is rotatably supported on the cylindrical portion 42l of the center shaft 42 by fitting in the circular hole 45a thereof the cylindrical portion 42l of the center shaft 42. The second middle rotor 68 is immovably secured on the center shaft 42 by fitting in the square hole 68a thereof the second flat engaging face 42k of the center shaft 42. The second control rotor 69 has a recessed circular bore 69b that accommodates therein an embedded thrust bearing 70. The second control rotor 69 is rotatably supported on the center shaft 42 by securely fitting the small cylindrical section 42h of the center shaft 42 in the circular hole 70a of the thrust bearing 70. A pair of slide pins 76 slidably engage the guide grooves 73-75.

The control rotor 45, second middle rotor 68, and second control rotor 69 are spaced apart in the axial direction. A spring holder 71 is fitted on the step section 42i formed on the leading end of the center shaft 42. A bolt 56 is tightened in the threaded bore 40b formed in the camshaft 40 to prevent the constituent elements of the second control rotor 69 and the like from coming off the shaft. The second electromagnetic clutch 72 is securely fixed on the engine casing (not shown) facing the front end of the second control rotor 69. The third embodiment is the same as the second embodiment in other respect.

Under the initial condition where there is no phase variation (FIG. 19(a)), the second middle rotor 68 and second control rotor 69 rotate in the clockwise direction D1 (FIG. 16) together with the control rotor 45. As in the second embodiment, the middle rotor 43 is delayed in phase angle (the phase varied in the angularly delaying direction D2) relative to the drive rotor due to the braking action of the electromagnetic clutch 44 retarding the control rotor 45 in the counterclockwise direction D2 relative to the middle rotor 43.

In this case, the third guide grooves 73 of the control rotor 45 rotate in the counterclockwise direction D2 relative to the second middle rotor 68 and second control rotor 69, as shown in FIGS. 18 and 19, so that the slide pins 76 are moved in the radial inward direction D8 in the guide grooves 73 and 74. The fourth guide grooves 75 are forced to move by the slide pins 76 moving in the radially inwardly. As a consequence, the second control rotor 69 is rotated in the clockwise direction D1 relative to the second middle rotor 68.

On the other hand, as the second electromagnetic clutch 72 is energized, the second control rotor 69 (or fourth guide grooves 75) is rotated from the position shown in FIG. 19(c) in the counterclockwise direction D2 relative to the control rotor 45 and second middle rotor 68 rotating in the clockwise direction D1. As a consequence, the slide pins 76 are moved radially inwardly (opposite to D8) in the guide grooves 74 and 75. The slide pins 76 moving radially outwardly force the third guide grooves 73 such that the control rotor 45 is rotated in the clockwise direction D1 relative to the second middle rotor 68. At the same time, the phase varying members 57 are moved radially inwardly since the control rotor 45 rotates in the clockwise direction D1 relative to the drive rotor. As a consequence, the phase angle of the middle rotor 43 is varied in the angularly advancing direction D1 relative to the drive rotor 41, as in the second embodiment.

Referring to FIGS. 20 through 24, there is shown a phase changing device for use with an automobile engine in accordance with the fourth embodiment of the invention. As in the second and third embodiments, the third embodiment has two electromagnetic clutches in the phase angle varying mechanism and phase angle restoration mechanism. In addition, the third embodiment utilizes a circular eccentric cam mechanism in the phase angle restoration mechanism.

In the fourth embodiment, there are provided a cam guide plate 77, a second control rotor second control rotor 78, a thrust bearing 79, a spring folder 80, electromagnetic clutches 44 and 81, all arranged ahead of the control rotor 45 in the order mentioned.

The control rotor 45 is provided with a recessed circular bore 45f formed in the front end thereof, and a circular eccentric cam 45h formed around the circular hole 45a. The circular eccentric cam 45h extend forward from the bottom 45g of the recessed circular bore 45f, and has a central axis L2 offset from the rotational axis L1 by a distance S1.

The second control rotor 78 has a central??? circular hole 78c and a circular eccentric cam 78b formed around the circular hole 78c which protrudes backward from the rear end 78a of the second control rotor 78 and has a central axis L3 offset from the axis L1 by the distance S1.

On the other hand, the cam guide plate 77 is provided on the opposite ends thereof with recessed oblong bores 77a and 77b in which the circular eccentric cams 45h and 78b are slidably fitted. The cam guide plate 77 is also provided with a generally square through hole 77c that extends in the direction perpendicular to the longest diameter of the oblong bores 77a and 77b.

The center shaft 42 is passed through the circular through hole 45a of the control rotor 45 such that the control rotor 45 is rotatably supported on the cylindrical section 42l of the center shaft 42. The inner circumference of the square hole 77c of the cam guide plate 77 is mounted on the second flat engagement surface 42k of the center shaft 42 such that the cam guide plate 77 is not rotatable relative to the center shaft 42 but slidable on the horizontal surface 42k1 of the second flat engagement surface 42k in the direction parallel to the long sides of the square through hole 77c. The second control rotor 78 is rotatably supported on the center shaft 42. This can be done by fitting on the small cylindrical section 42h of the center shaft 42 the inner circumference of the circular hole 79a of the thrust bearing 79 embedded in the recessed circular bore 78d.

The circular eccentric cams 45h and 78b engage the respective recessed oblong bores 77a ad 77b. Thus, when the control rotors 45 and 78 rotate relative to the cam guide plate 77, the circular eccentric cams 45h and 78b slidably reciprocate in the respective recessed oblong bores 77a and.

The control rotor 45, cam guide plate 77, and second control rotor 78 are spaced apart in the axial direction. The spring holder 80 is fitted in the recess 42i formed in the front end of the center shaft 42. A bolt 56 is tightly screwed in a threaded bore 40b of the camshaft 40 to prevent the elements of the second control rotor 78 and the like from coming off the camshaft 42. The second electromagnetic clutch 81 is securely fixed on the engine casing (not shown) facing the front end of the second control rotor 69. The fourth embodiment is the same as the foregoing embodiments in other respects.

As shown in FIGS. 23(a)-(c), under the initial condition where there is no phase variation, the cam guide plate 77 is located at the far right end inside the recessed circular bore 45f, where the circular eccentric cam 78b is positioned with its central axis L3 inclined at an angle of θ in the clockwise direction D1 with reference to the horizontal axis L4 as shown in FIG. 23(a), while the circular eccentric cam 45h is positioned with its central axis L2 inclined at an angle of θ in the counterclockwise direction D2 with reference to the horizontal axis L4, as shown in FIG. 23(c).

Under the initial condition where there is no phase variation, the cam guide plate 77 and second control rotor 78 rotate in the clockwise direction D1 together with the control rotor 45. Under the braking action of the electromagnetic clutch 44 on the control rotor 45, the control rotor 45 is rotated relative to the middle rotor 43, as in the second and third embodiments, thereby varying the phase angle of the middle rotor 43 in the angularly delaying direction (that is, in the counterclockwise direction D2).

Under such condition, the circular eccentric cams 45h integrated to the control rotor 45 is rotated from the position shown in FIGS. 23(c) and 24(a) about the rotational axis L1 in the counterclockwise direction D2 with reference to the horizontal axis L4, possibly through the maximum permissible angle of 180°-θ. At the same time, the circular eccentric cam 45h slidably moves upward inside the oblong bore 77a until the central axis L2 moves past the vertical axis L5, and then moves downwardly, so that the cam guide plate 77 is displaced to the left until it reaches, in the case of maximum displacement, the left end of the inner circumference of the recessed bore 45f.

In this case, the circular eccentric cam 78b is subjected to the external force applied thereto by the oblong bore 77b of the cam guide plate 77 and rotates in the clockwise direction D1 about the rotational axis L1 from the position shown in FIGS. 23(a) and 24(a) and reciprocates up and down inside the oblong bore 77b. As a consequence, the second control rotor 78 which is integral with the circular eccentric cam 78b rotates in the clockwise direction D1 relative to the control rotor 45 until the central axis L3 of the circular eccentric cam 78b is possibly inclined to the maximum permissible angle of 180°-θ in the clockwise direction D1 with reference to the horizontal axis L4.

On the other hand, when the second electromagnetic clutch 81 is energized, the second control rotor 78 (circular eccentric cam 78b) is rotated in the counterclockwise direction D2 relative to the control rotor 45 which is rotating in the clockwise direction D1, thereby slidably reciprocating up and down on the inner circumference of the oblong bore 77b. As a consequence, the cam guide plate 77 is displaced to the right (in the direction opposite to the direction D9) until it reaches the right end of the recessed circular bore 45f. Because of the rotational motion of the circular eccentric bore 45h in the clockwise direction D1 under an external force applied thereto by the oblong bore 77b of the cam guide plate 77, the control rotor 45 is rotated in the clockwise direction D1 relative to the second control rotor 78. Since the control rotor 45 rotates in the clockwise direction D1 relative to the drive rotor 41, the phase varying members 57 are moved radially outwardly. As a consequence, the phase angle of the middle rotor 43 is varied in the angularly advancing direction relative to the drive rotor (rotated in the clockwise direction D1), as in the second and third embodiment.

It should be noted that in the second through fourth embodiments use of an electromagnetic clutch for varying phase angle of the middle rotor 43 eliminates need of a coil spring used in the first embodiment. This means that energy can be saved by cutting off the electricity to the electromagnetic clutch 44 soon after a required phase alteration is achieved. Accordingly, downsizing of the electromagnetic clutch 44 is possible, since it requires a less torque.

Although a torsion spring is used in combination with an electromagnetic clutch as a torque means in the first through fourth embodiments, an electric motor can be alternatively used to directly provide the control rotor with a torque, or still alternatively, a hydraulic pressure chamber may be used to provide the torque.

Although a thrust bearing is used between the control rotor and spring holder in the first embodiment and between the second control rotor and spring holder in the second and fourth embodiment, a disc spring may be alternatively used. When a disc spring is used, a frictional torque is generated in the control rotor and second control rotor, which advantageously generates an inertial force in the control rotor when an abrupt change occurs in engine rpm, for example, and can eliminate unanticipated abrupt change in phase angle between the camshaft and the drive rotor.

PHASE CHANGING DEVICE FOR AUTOMOBILE ENGINE

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