Valve timing controller

A valve timing controller includes: an outer rotor; an inner rotor relatively rotating inside of the outer rotor; a torsion coil spring having a fixed end connected with the inner rotor, and a free end connected with the outer rotor; and a bush rotor coaxially projected from the outer rotor or the inner rotor to support the torsion coil spring in a radial direction. The torsion coil spring biases the inner rotor while being connected with the outer rotor by being torsionally deformed according to a relative rotation of the inner rotor to the outer rotor. A load acting from a first turn of the torsion coil spring adjacent to the free end is smaller than a load acting from a wound part of the torsion coil spring between the first turn and the fixed end.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2015-180002 filed on Sep. 11, 2015, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a valve timing controller.

BACKGROUND

A valve timing controller includes an outer rotor and an inner rotor rotating with a crankshaft and a camshaft, respectively, around a rotation axis. The inner rotor is relatively rotated inside the outer rotor to control valve timing according to the rotation phase between the outer rotor and the inner rotor by the relative rotation.

JP 4487957 B2 (corresponding to US 2007/0215085 A1) describes a valve timing controller equipped with a torsion coil spring wound in the shape of coil around a rotation axis. The torsion coil spring has a fixed end connected with the inner rotor, and a free end connected with the outer rotor. The torsion coil spring biases the inner rotor while being connected with the outer rotor by being twistingly deformed according to the relative rotation of the inner rotor to the outer rotor. Thereby, while an internal-combustion engine is stopped, the rotation phase can be forced to a phase suitable for starting due to the biasing force of the torsion coil spring. As a result, an expected valve timing will be realized.

The valve timing controller further includes a bush rotor projected coaxially from the inner rotor. The bush rotor supports the torsion coil spring in the radial direction to stabilize the biasing force of the torsion coil spring. The bush rotor has a cylindrical shape with a center axis aligned with the rotation axis. The torsion coil spring is a wound coil having a center axis aligned with the rotation axis. Since the orientation of the torsion coil spring supported by the bush rotor becomes difficult to change, it becomes possible to realize a predetermined valve timing by restricting the biasing force from being affected.

SUMMARY

However, the first turn of the torsion coil spring adjacent to the free end is displaced relative to the rotation axis due to the torsional deformation. The first turn adjacent to the free end may be pressed onto the bush rotor by the displacement. As a result, since the torsion coil spring receives stress concentration at the pressed position, the torsion coil spring may suffer fatigue destruction due to the repetition of the stress concentration.

It is an object of the present disclosure to provide a valve timing controller with high durability.

According to an aspect of the present disclosure, a valve timing controller that controls a valve timing of a valve opened and closed by a camshaft based on torque transfer from a crankshaft in an internal-combustion engine includes: an outer rotor that rotates with the crankshaft around a rotation axis; an inner rotor that rotates with the camshaft around the rotation axis, the inner rotor relatively rotating inside of the outer rotor; a torsion coil spring having a coil shape wound around the rotation axis, the torsion coil spring having a fixed end connected with the inner rotor, and a free end connected with the outer rotor, the torsion coil spring biasing the inner rotor while being connected with the outer rotor by being tortionally deformed according to a relative rotation of the inner rotor to the outer rotor; and a bush rotor coaxially projected from the outer rotor or the inner rotor. The bush rotor supports the torsion coil spring in a radial direction. A load acting from a first turn of the torsion coil spring adjacent to the free end is smaller than a load acting from a wound part of the torsion coil spring that is located between the first turn and the fixed end.

Accordingly, the first turn adjacent to the free end is displaced relative to the rotation axis by the torsional deformation, and is pressed onto the bush rotor. At this time, the load which acts on the bush rotor by the first turn of the torsion coil spring adjacent to the free end is smaller than the load which acts on the bush rotor from the wound part between the fixed end and the first turn adjacent to the free end. Therefore, the stress concentration can be reduced in the torsion coil spring at the position pressed onto the bush rotor. Thus, the torsion coil spring can be restricted from having fatigue destruction by repetition of such stress concentration, so as to improve the durability.

The bush rotor may support the torsion coil spring inside of the bush rotor. When a specific position is defined at a circumferential position opposite to the free end through the rotation axis, the load acting from the first turn adjacent to the free end to the bush rotor is smaller than the load acting from the wound part, at the specific position.

Accordingly, when the torsion coil spring is torsionally deformed inside of the bush rotor, the first turn adjacent to the free end is easily displaced away from the free end through the rotation axis. As a result, the first turn adjacent to the free end is easily pressed onto the bush rotor at the specific position defined as a circumferential position opposite to the free end through the rotation axis. At this time, at the specific position of the torsion coil spring, the load which acts on the bush rotor from the first turn adjacent to the free end is smaller than the load which acts on the bush rotor from the wound part between the fixed end and the first turn adjacent to the free end. According to this, the stress concentration can be reduced at the position where the torsion coil spring is pressed. Therefore, the torsion coil spring can be restricted from having fatigue destruction by reducing the stress concentration, and the high durability can be secured.

The bush rotor may support the torsion coil spring outside of the bush rotor. When a specific position is defined at a circumferential position at which the free end is set, the load acting from the first turn adjacent to the free end to the bush rotor is smaller than the load acting from the wound part, at the specific position.

Accordingly, when the torsion coil spring is torsionally deformed outside of the bush rotor, the first turn adjacent to the free end is easily displaced away from the free end through the rotation axis. As a result, the first turn adjacent to the free end is easily pressed onto the bush rotor at the specific position defined as the circumferential position where the free end is set. At this time, the load which acts on the bush rotor from the first turn adjacent to the free end is smaller than the load which acts on the bush rotor from the wound part between the fixed end and the first turn adjacent to the free end, at the specific position of the torsion coil spring. According to this, the stress concentration can be reduced at the position where the torsion coil spring is pressed. Therefore, the torsion coil spring can be restricted from having fatigue destruction by reducing the stress concentration, and the high durability can be secured.

DETAILED DESCRIPTION

As shown inFIG. 1which is a cross-sectional view taken along a line I-I ofFIG. 2, a valve timing controller1according to a first embodiment is a hydraulic controller using pressure of operation oil. The valve timing controller1is installed in a transfer system where a crank torque output from a crankshaft is delivered to a camshaft2in an internal-combustion engine. The camshaft2drives an exhaust valve to open or close by transfer of the crank torque from the crankshaft. The valve timing controller1controls the valve timing of a valve such as the exhaust valve.

As shown inFIGS. 1-4, the valve timing controller1includes an outer rotor10, an inner rotor20, a bush rotor40, and a torsion coil spring50. The valve timing controller1controls the valve timing according to a rotation phase between the outer rotor10and the inner rotor20by relatively rotating the inner rotor20with operation oil inside of the outer rotor10.

The outer rotor10is a housing rotor. Specifically, the outer rotor10is made of metal, and has a shoe housing12, a sprocket plate13and a cover plate14screwed to the axial ends of the shoe housing12respectively. As shown inFIGS. 1 and 2, the shoe housing12has an accommodation pipe120and plural shoes122. Each shoe122is projected with an approximately sector shape inward in the radial direction from the accommodation pipe120at positions spaced in the circumferential direction at a predetermined interval. An accommodation chamber123is formed between the shoes122adjacent to each other in the circumferential direction.

As shown inFIGS. 1-4, the sprocket plate13has sprocket teeth133. Each sprocket tooth133is projected with an approximately sector shape outward in the radial direction from the sprocket plate13at positions spaced in the circumferential direction at a regular interval. A timing chain is engaged with the sprocket teeth133and teeth of the crankshaft, such that the sprocket plate13is engaged with the crankshaft. Thereby, the sprocket plate13receives the crank torque from the crankshaft through the timing chain during the operation of the internal-combustion engine. At this time, the outer rotor10rotates to one side (clockwise rotation inFIGS. 2 and 3) with the crankshaft in the circumferential direction around the rotation axis O.

As shown inFIG. 1, the sprocket plate13has a main hole130passing through the sprocket plate13in the axial direction. The sprocket plate13is supported by the camshaft2coaxially fitted to the main hole130.

As shown inFIGS. 1, 3, and 4, the cover plate14has a connection stopper140. The connection stopper140has a pillar pin shape arranged to be eccentric to the rotation axis O. The connection stopper140is projected outward from an end surface of the cover plate14opposite from the shoe housing12in the axial direction.

As shown inFIGS. 1-4, the inner rotor20is a vane rotor made of metal and held in the outer rotor10.

The inner rotor20has a rotation shaft200and plural vanes202. The rotation shaft200has a cylindrical shape arranged coaxially inside the outer rotor10. The rotation shaft200has an annular recess portion201and a connection groove portion203. The annular recess portion201is formed as a ring slot opened toward the cover plate14in the axial direction. The connection groove portion203is formed as a rectangle slot opened to the inside of the annular recess portion201. In other words, the connection groove portion203is defined in the internal surface of the annular recess portion201.

As shown inFIG. 1, the rotation shaft200is connected with the camshaft2inserted coaxially inside the outer rotor10through the main hole130. The inner rotor20rotates to one side (clockwise rotation inFIGS. 2 and 3) in the circumferential direction with the camshaft2around the rotation axis O during the operation of the internal-combustion engine. At this time, the inner rotor20is able to rotate relative to the outer rotor10on the both sides in the circumferential direction. While the inner rotor20and the outer rotor10are relatively rotated, one end and the other end of the rotation shaft200in the axial direction are respectively made to slide on the sprocket plate13and the cover plate14. Further, an outer circumference of the rotation shaft200is made to slide on the projection tip end of each shoe122in the radial direction.

As shown inFIG. 2, each vane202is projected with the shape of approximately sector outward in the radial direction from the rotation shaft200at positions spaced at a predetermined interval in the circumferential direction. Each vane202is projected into the corresponding accommodation chamber123. One end and the other end of each vane202in the axial direction are made to slide on the sprocket plate13and the cover plate14, respectively, during the relative rotation between the outer rotor10and the inner rotor20. The projection tip end of each vane202is made to slide on the inner circumference of the accommodation pipe120in the radial direction.

Inside of the outer rotor10, each vane202partitions the corresponding accommodation chamber123in the circumferential direction, such that an advance operation chamber34and a retard operation chamber35are formed by each vane202. When operation oil is introduced from a pump to each advance operation chamber34by the operation of an oil pressure control valve, the running torque is generated in the internal-combustion engine to relatively rotate the inner rotor20on the advance side Da in the circumferential direction relative to the outer rotor10. At this time, in the internal-combustion engine, operation oil is drained from each retard operation chamber35by the operation of the oil pressure control valve. Thus, the rotation phase of the inner rotor20to the outer rotor10is advanced to advance the valve timing.

On the other hand, in the internal-combustion engine, when operation oil is introduced from a pump to each retard operation chamber35by the operation of oil pressure control valve, the running torque occurs to relatively rotate the inner rotor20on the retard side Dr in the circumferential direction relative to the outer rotor10. At this time, operation oil is drained from each advance operation chamber34by the operation of the oil pressure control valve in the internal-combustion engine, such that the rotation phase is retarded to retard the valve timing.

A stopper vane202S is specific one of the vanes202, and is projected into the accommodation chamber123between the stopper shoes122a,122rwhich are specific two of the shoes122. As shown in the solid line inFIG. 2, the advance stopper shoe122ais in contact with the stopper vane202S rotated relative to the outer rotor10on the advance side Da in the circumferential direction, thereby stops the motion of the inner rotor20to the advance side Da. Thus, the rotation phase is restricted from changing to the advance side Da at the maximum advance phase. On the other hand, as shown in the two-point chain line ofFIG. 2, the retard stopper shoe122ris in contact with the stopper vane202S relatively rotated to the outer rotor10on the retard side Dr in the circumferential direction, thereby stops the motion of the inner rotor20to the retard side Dr. The rotation phase is restricted from changing to the retard side Dr at the maximum retard phase. Accordingly, the relatively rotatable range of the inner rotor20to the outer rotor10is set as a range from the maximum advance phase to the maximum retard phase.

As shown inFIGS. 1 and 3-5, the bush rotor40is formed in the cylinder shape with a center axis Cb aligned with the rotation axis O, and is made of metal. The bush rotor40is coaxially projected out of the outer rotor10from the end surface of the cover plate14opposite from the shoe housing12in the axial direction. Therefore, during the operation of the internal-combustion engine, the bush rotor40rotates integrally with the outer rotor10to one side (clockwise rotation inFIG. 2) in the circumferential direction around the rotation axis O. The bush rotor40of this embodiment is integrally formed with the cover plate14. Alternatively, the bush rotor40may be fixed to the cover plate14to be able to integrally rotate after the cover plate14is formed separately.

As shown inFIGS. 1, 3, and 4, the bush rotor40has a cutout window400opposite side of the cover plate14in the axial direction. The cutout window400is formed in an arc cutout opened to the axially projection side, the radially inner side, and the radially outer side in the bush rotor40. Thereby, the cutout window400is arranged at a circumferential position opposite to a specific position Ps (to be described later) through the rotation axis O. In other words, the position of the cutout window400corresponds to the free end500of the torsion coil spring50, in the circumferential position of the bush rotor40around the rotation axis O.

As shown inFIGS. 1-5, the torsion coil spring50is a kind of torsion spring produced by winding a wire made of metal in the shape of a coil around the rotation axis O. The torsion coil spring50is arranged to be located from the inside to the outside of the outer rotor10. The torsion coil spring50has the free end500and the fixed end501defined by, respectively the both ends of the wire. The torsion coil spring50of this embodiment is partially accommodated inside the bush rotor40except for the free end500and the fixed end501. The bush rotor40supports the torsion coil spring50inside the bush rotor40in the radial direction.

As shown inFIGS. 1, 3, and 4, the free end500is positioned out of the outer rotor10. The free end500is bent to extend to the outer circumference from the first turn502adjacent to the free end500, and is extended to the outer circumference of the bush rotor40through the cutout window400. The connection stopper140supports and stops the free end500from the retard side Dr, and the free end500is connected with the outer rotor10. Thereby, the free end500is restricted from moving on the retard side Dr relative to the outer rotor10, and is flexibly movable on the advance side Da. The specific position Ps is defined at a set position opposite to the free end500through the rotation axis O, in the circumferential position around the rotation axis O.

As shown inFIGS. 1-3, the fixed end501is arranged inside the outer rotor10. The fixed end501is bent toward the inner circumference from the first turn503adjacent to the fixed end501, and is extended to the inner circumference from the annular recess portion201in which the first turn503is received. The fixed end501is fitted to the connection groove portion203, and is connected with the inner rotor20. Thereby, the fixed end501is in the fixed state where both the motion on the retard side Dr and the motion on the advance side Da are always stopped relative to the inner rotor20.

Under such condition, when the inner rotor20is relatively rotated on the retard side Dr relative to the outer rotor10, the torsion coil spring50twists and is deformed according to the relative rotation. At this time, the restoring force of the torsion coil spring50acts on the retard side Dr to the outer rotor10, and acts on the advance side Da to the inner rotor20. Thereby, the torsion coil spring50biases the inner rotor20on the advance side Da relative to the outer rotor10in the whole region of the relatively rotatable range, while maintaining cooperation with the outer rotor10.

Under cooperation with the outer rotor10and the inner rotor20, the torsion coil spring50becomes the maximum restoration state Sr shown inFIGS. 1-5, and 6Awhere the torsion coil spring50is restored to the maximum when the rotation phase between the rotors10and20reaches the maximum advance phase. When the rotation phase between the rotors10and20reaches the maximum retard phase, the torsion coil spring50becomes in the maximum deformation state St shown inFIG. 6Cwhere the torsion coil spring50is twisted and deformed to the maximum.

The details of the torsion coil spring50according to the first embodiment are explained.

As shown inFIG. 5, the torsion coil spring50has a coil axis Cc inclined to the rotation axis O of both the rotors10and20toward the free end500. That is, the torsion coil spring50is wound in the shape of an odd-form coil. In this embodiment, the torsion coil spring50is wound in the shape of the odd-form coil inclined, while the diameter of the coil is substantially fixed, between the free end500and the fixed end501. The inclination angle θc of the coil axis Cc relative to the rotation axis O is approximately coincident with the inclination angle θo of a tangent Lo circumscribed to the torsion coil spring50relative to the rotation axis O at the specific position Ps in the maximum restoration state Sr shown inFIGS. 5 and 6A.

Therefore, while the torsion coil spring50is connected with both the rotors10and20, as shown inFIGS. 1, 3, 5, and 6A, a clearance60is defined between the first turn502of the torsion coil spring50adjacent to the free end500and the bush rotor40at the specific position Ps in the maximum restoration state Sr. At this time, at the specific position Ps in the maximum restoration state Sr, the second turn adjacent to the fixed end501is in contact with the bush rotor40as the wound part504of the torsion coil spring50between the first turn502adjacent to the free end500and the fixed end501. At the specific position Ps in such maximum restoration state Sr, the load Fa which acts on the bush rotor40from the first turn502adjacent to the free end500is smaller than the load Fb which acts on the rotor40from the wound part504between the first turn502adjacent to the free end500and the fixed end501. That is, the load relation of Fa<Fb is satisfied.

The load Fa that acts on the bush rotor40from the first turn502at the specific position Ps in the maximum restoration state Sr is substantially zero or minute due to the clearance60. InFIG. 6A, the virtual line arrow (namely, two-point chain line) schematically shows the load Fa.

Furthermore, in the process where the torsional deformation advances from the maximum restoration state Sr ofFIG. 6AtoFIGS. 6B and 6Cin this order, the first turn502of the torsion coil spring50adjacent to the free end500is displaced to approach the bush rotor40at the specific position Ps. The load Fa which acts from the first turn502is smaller than the load Fb which acts from the wound part504even at the specific position Ps of the bush rotor40in the process where the torsional deformation advances.

When the torsional deformation advances as shown inFIG. 6B, the inclination angle θo of the tangent Lo to the rotation axis O decreases, and the clearance60between the first turn502and the bush rotor40also decreases. However, also at this time, the load Fa is substantially zero or minute, that is, smaller than the load Fb at the specific position Ps. Also inFIG. 6B, the virtual line arrow (namely, two-point chain line) schematically shows the load Fa. Moreover, while the torsional deformation advances to the maximum deformation state St shown inFIG. 6Cfrom a middle deformation state shown inFIG. 6B, the first turn502contacts the bush rotor40at the specific position Ps. While the first turn502contacts the bush rotor40, the load relation of Fa<Fb is maintained in this embodiment.

Advantages of the first embodiment are explained below.

According to the first embodiment, the first turn502of the torsion coil spring50adjacent to the free end500is displaced relative to the rotation axis O in connection with the torsional deformation, and is pressed onto the bush rotor40. At this time, the load Fa which acts on the bush rotor40from the first turn502of the torsion coil spring50adjacent to the free end500is smaller than the load Fb which acts on the bush rotor40from the wound part504between the fixed end501and the first turn502adjacent to the free end500. Therefore, the stress concentration can be reduced in the torsion coil spring50at the position pressed onto the bush rotor40. Thus, fatigue destruction of the torsion coil spring50can be reduced by restricting the repetition of such stress concentration, such that the durability can be improved.

Moreover, the first turn502is easily displaced away from the free end500through the rotation axis O when the torsion coil spring50is torsionally deformed on the outer circumference of the bush rotor40. As a result, the first turn502is easily pressed onto the bush rotor40at the specific position Ps defined as the circumferential position opposite to the free end500through the rotation axis O. At this time, at the specific position Ps of the torsion coil spring50, the load Fa which acts on the bush rotor40from the first turn502is smaller than the load Fb which acts on the bush rotor40from the wound part504. According to this, the stress concentration can be reduced in the torsion coil spring50at the position pressed onto. Therefore, the fatigue destruction of the torsion coil spring50can be reduced by easing the stress concentration, such that the high durability is secured.

While the torsion coil spring50is connected with both the rotors10and20, at the specific position Ps of the torsion coil spring50set to the maximum restoration state Sr, the load Fa which acts on the bush rotor40from the first turn502is smaller than the load Fb which acts on the bush rotor40from the wound part504. Thus, the stress concentration can be reduced at the position pressed onto the bush rotor40, not only for the torsion coil spring50in the maximum restoration state Sr, but also for the torsion coil spring50in the process advancing from the maximum restoration state Sr to the torsional deformation state Sr. Therefore, the fatigue destruction of the torsion coil spring50can be reduced irrespective of the rotation phase between the rotors10and20, such that the high durability is attained.

At the specific position Ps of the torsion coil spring50set to the maximum restoration state Sr while connected with both the rotors10and20, the wound part504is in contact with the bush rotor40, and the clearance60is defined between the bush rotor40and the first turn502. As a result, at the specific position Ps, the load Fa which acts on the bush rotor40from the first turn502is secured to be smaller than the load Fb which acts on the bush rotor40from the wound part504. Therefore, for the torsion coil spring50, the stress concentration can be certainly restricted at the position forced onto the bush rotor40in the process advancing from the maximum restoration state Sr to the torsional deformation state. Thus, it becomes possible to reliably secure the high durability by effectively controlling the fatigue destruction of the torsion coil spring50.

In addition, the bush rotor40has the cylindrical shape with the center axis Cb aligned with the rotation axis O, and supports the torsion coil spring50in the radial direction. The torsion coil spring50is an odd-form coil having the coil axis Cc inclined toward the free end500relative to the rotation axis O. At the specific position Ps of the torsion coil spring50set into the maximum restoration state Sr while being connected with both the rotors10and20, the wound part504is in contact with the bush rotor40, and the clearance60can be secured between the first turn502and the bush rotor40. Therefore, the load Fa which acts on the bush rotor40from the first turn502can be easily secured to be smaller than the load Fb which acts on the bush rotor40from the wound part504at the specific position Ps. Thus, the bush rotor40having the cylindrical shape and the torsion coil spring50having the inclined shape of odd-form coil are effective for securing the high durability.

A second embodiment is a modification of the first embodiment, and is described with reference toFIG. 7.

The bush rotor2040of the second embodiment is arranged to range over from the inside to the outside of the outer rotor10. The bush rotor2040is coaxially projected from the inner rotor20outside of the outer rotor10through the inner circumference side of the cover plate14. While the internal-combustion engine is operated, the bush rotor40rotates integrally with the inner rotor20to one side in the circumferential direction around the rotation axis O. The bush rotor2040is fixed to the rotation shaft200produced separately as another object, and is able to rotate integrally with the rotation shaft200. The bush rotor2040may be integrally formed with the rotation shaft200. In the other aspects, the bush rotor2040is approximately the same as the bush rotor40of the first embodiment.

According to the second embodiment, the clearance60is defined between the bush rotor2040and the first turn502adjacent to the free end500, at the specific position Ps in the maximum restoration state Sr, for the torsion coil spring50connected with both the rotors10and20. Therefore, the same action and effect can be achieved as the first embodiment.

A third embodiment is a modification of the second embodiment, and is described with reference toFIG. 8.

In the third embodiment, the torsion coil spring50is arranged outside of the bush rotor3040projected from the inner rotor20. Thereby, the bush rotor3040supports the torsion coil spring50on the outer side in the radial direction. Moreover, the cutout window400is not formed in the bush rotor3040of the third embodiment. Then, the free end500is bent radially outward from the first turn502adjacent to the free end500, and is extended toward the connection stopper140. Moreover, the specific position Ps is defined as the circumferential position around the rotation axis O where the free end500is set. In addition, in the third embodiment, the fixed end501is bent outward from a first turn503adjacent to the fixed end501, and is fitted to the connection groove portion203.

According to the third embodiment, the clearance60is defined between the first turn502adjacent to the free end500and the bush rotor3040at the specific position Ps in the maximum restoration state Sr for the torsion coil spring50engaged with both the rotors10and20. Therefore, when the torsion coil spring50is torsionally deformed outside the bush rotor3040, the first turn502is easily displaced away from the free end500through the rotation axis O. As a result, the first turn502is easily pressed onto the bush rotor3040at the specific position Ps defined as the circumferential position where the free end500is set. Therefore, the same action and effect can be achieved as the first embodiment.

As shown inFIG. 9, in a first modification about the first to third embodiments, the torsion coil spring50may be an odd-form coil in which the diameter of the coil is decreased from the fixed end501to the free end500and in which the coil axis Cc inclines toward the free end500relative to the rotation axis O. In this case, at the specific position Ps in the maximum restoration state Sr, the inclination angle θo of the tangent Lo to the rotation axis O is larger than the inclination angle θc of the coil axis Cc to the rotation axis O. In addition,FIG. 9shows the first modification of the first embodiment.

As shown inFIG. 10, in a second modification about the first to third embodiments, the torsion coil spring50may be an odd-form coil having the coil axis Cc aligned with the rotation axis O in which the diameter of the coil is decreased from the fixed end501to the free end500. In addition,FIG. 10shows the second modification of the first embodiment.

As shown inFIG. 11, in a third modification about the first to third embodiments, the torsion coil spring50may be an odd-form coil having the coil axis Cc aligned with the rotation axis O in which the diameter of the coil is smaller at the free end500than at the wound part504. In addition,FIG. 11shows the third modification of the first embodiment, in which the diameter of the first turn502adjacent to the free end500is smaller than that of the other portion such as the wound part504.

As shown inFIGS. 12 and 13, in a fourth modification about the first to third embodiments, the bush rotor40,2040,3040may have an inclination cylinder shape with the center axis Cb inclined away from the free end500relative to the rotation axis O. In this case, as shown inFIG. 12, the torsion coil spring50may be wound in the shape of odd-form coil similarly to the first to third embodiments, or the first to third modifications described above. Alternatively, as shown inFIG. 13, the torsion coil spring50has the coil axis Cc aligned with the rotation axis O in which the diameter of the coil is approximately constant to present the shape of straight cylindrical coil.

In a fifth modification about the first to third embodiments, the clearance60is not defined. Specifically, the first turn502adjacent to the free end500contacts the bush rotor40at the specific position Ps in the maximum restoration state Sr, while the load relation of Fa<Fb is satisfied. In this case, the coil axis Cc is made inclined for the torsion coil spring50free from both the rotors10and20in a natural length state, for example, by an angle required for satisfying the load relation of Fa<Fb.

In a sixth modification about the first to third embodiments, the torsion coil spring50may be arranged to bias the inner rotor20on the retard side Dr relative to the outer rotor10while connected with the outer rotor10. In this case, the connection stopper140is engaged with the free end500from the advance side Da.

In a seventh modification about the first to third embodiments, the torsion coil spring50may be deformed to bias the inner rotor20while being connected with the outer rotor10in a part of the relatively rotatable range. In this case, in the remainder of the relatively rotatable range, the torsion coil spring50is not connected with the outer rotor10, and does not bias the inner rotor20.

The valve timing controller may control the valve timing of an intake valve as a valve other than the exhaust valve.

Such changes and modifications are to be understood as being within the scope of the present disclosure as defined by the appended claims.