Patent Publication Number: US-2013233263-A1

Title: Valve timing controller

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based on Japanese Patent Application No. 2012-49305 filed on Mar. 6, 2012, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a valve timing controller. 
     BACKGROUND 
     JP-11-132014A (U.S. Pat. No. 6,039,016) describes a valve timing controller which controls valve timing of an intake valve or an exhaust valve of an internal combustion engine. The valve timing controller has an advance oil pressure chamber and a retard oil pressure chamber between a vane rotor and a housing which have relative rotation with each other. The valve timing controller further has a torsion spring which generates a relative rotation phase between the vane rotor and the housing. 
     For example, the torsion spring generates a torque biasing the vane rotor to rotate in an advance direction relative to the housing. The valve timing controller produces a phase difference between the vane rotor and the housing by controlling the pressure of hydraulic fluid, corresponding to the torque of the torsion spring, so as to control the valve timing of the intake valve or the exhaust valve. 
     Because both ends of the torsion spring are inclined relative to a plane which is perpendicular to the rotation axis direction, the center axis of the torsion spring may be inclined relative to the rotation axis direction when the torsion spring is secured to the valve timing controller. In this case, a load generated by the torque of the torsion spring is also inclined relative to the rotation axis direction. If the housing is inclined to the vane rotor in the rotation axis direction, a wearing is easily generated between the vane rotor and the housing. Moreover, if the torsion spring is inclined relative to the rotation axis direction, assembling of components such as fitting bolt may become difficult when the valve timing controller is manufactured. 
     SUMMARY 
     It is an object of the present disclosure to provide a valve timing controller in which a vane rotor and a housing are restricted from having inclination relative to each other. 
     According to an example of the present disclosure, a valve timing controller that opens and closes an intake valve and an exhaust valve by rotating a driven shaft using a driving force of a driving shaft of an internal combustion engine and that controls open and close timing of at least one of the intake valve and the exhaust valve by changing a rotation phase between the driving shaft and the driven shaft includes a housing, a vane rotor, a bush, a coil spring, and a retainer. The housing rotates with one of the driving shaft and the driven shaft. The vane rotor rotates with the other of the driving shaft and the driven shaft, and has a vane accommodated in an accommodation chamber defined in the housing. T rotation phase of the vane rotor relative to the housing is changed using a pressure of hydraulic fluid supplied to a pressure chamber defined by partitioning the accommodation chamber with the vane. The cylindrical bush is fixed to the vane rotor, and supports the housing in a relatively rotatable state. The coil spring is provided to the bush and has a first end engaged with the vane rotor and a second end engaged with the housing. The coil spring generates a biasing torque biasing the vane rotor to rotate relative to the housing. The retainer contacts the coil spring at least one point when projected to a plane perpendicular to a rotation axis direction. The retainer retains a posture of the coil spring to be kept parallel with the rotation axis direction. 
     Accordingly, when the coil spring contacts the retainer, the center axis of the coil spring becomes parallel with the rotation axis direction, thus the posture of the coil spring is retained to be parallel with the rotation axis direction. Therefore, when the housing and the vane rotor rotate relative to each other due to the torque of the coil spring, the torque of the coil spring becomes perpendicular to the rotation axis direction. Thus, relative inclination in the rotation axis direction can be reduced between the housing and the vane rotor, and wearing can be reduced between the housing and the vane rotor. 
     Moreover, the coil spring is restricted from displacing in the radial direction, so components located adjacent to the coil spring can be flexibly arranged. 
     Furthermore, because the retainer and the coil spring contact with each other at the point, the contact area between the retainer and the coil spring can be reduced compared with a case where the retainer and the coil spring contact with each other on a plane. Accordingly, the friction resistance between the retainer and the coil spring can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: 
         FIG. 1  is a schematic view illustrating a valve timing controller according to a first embodiment; 
         FIG. 2  is a schematic view illustrating a power train system having the valve timing controller of the first embodiment; 
         FIG. 3  is a schematic cross-sectional view taken along a line III-III of  FIG. 1 ; 
         FIG. 4  is a schematic side view seen from a direction IV of  FIG. 1 ; 
         FIG. 5  is a schematic cross-sectional view illustrating a bush and a coil spring of the valve timing controller of the first embodiment; 
         FIG. 6  is a schematic cross-sectional view illustrating a valve timing controller according to a second embodiment; 
         FIG. 7  is a schematic side view seen from a direction VIII of  FIG. 6 ; 
         FIG. 8  is a schematic side view illustrating a valve timing controller according to a third embodiment; 
         FIG. 9  is a schematic cross-sectional view taken along a line IX-O-P-Q-IX of  FIG. 8 ; and 
         FIG. 10  is a schematic side view illustrating a valve timing controller according to a fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure will be described hereafter referring to drawings. In the embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned with the same reference numeral, and redundant explanation for the part may be omitted. When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination. 
     First Embodiment 
     A valve timing controller  1  according to a first embodiment will be described with reference to  FIGS. 1 to 5 . The valve timing controller  1  is, for example, an oil-pressure control type controller which uses oil as working hydraulic fluid. 
     As shown in  FIG. 2 , the valve timing controller  1  is applied to a roller locker type power train system of an engine  91 , in which a chain  97  is engaged with a gear  93  fixed to a crankshaft  92 , a gear  115  fixed to a camshaft  94 , and a gear  96  fixed to a camshaft  95 . The crankshaft  92  may correspond to a driving shaft, and the camshaft  94 ,  95  may correspond to a driven shaft. Driving force is transmitted to the camshafts  94  and  95  from the crankshaft  92 . The camshaft  94  opens and closes an exhaust valve  99  via a cam mechanism, and the camshaft  95  opens and closes an intake valve  98  via a cam mechanism. The valve timing controller  1  of the first embodiment controls the opening and closing timing of, for example, the exhaust valve  99 . 
     The valve timing controller  1  will be described hereinafter with reference to  FIGS. 1-5 .  FIG. 1  illustrates a cross-sectional view of the valve timing controller  1  corresponding to a line I-O-P-Q-I of  FIG. 4 . The valve timing controller  1  is arranged inside a cover of the engine  91 , and has a housing  10 , a vane rotor  20 , a bush  31 , a coiled spring  40 , and a retainer  51 . 
     The housing  10  has a sprocket  11 , a shoe housing  12  formed into a cylinder shape, and a front plate  13  formed into a disc shape. The shoe housing  12  and the front plate  13  are integrated with each other. 
     The sprocket  11 , the shoe housing  12 , and the front plate  13  are coaxially fixed using a bolt, and the shoe housing  12  is located between the front plate  13  and the sprocket  11 . 
     The sprocket  11  has a board shape, and the gear  115  is defined on the outer circumference of the sprocket  11 . The sprocket  11  is linked with the crankshaft  92  through the chain  97 . When a driving force is transmitted from the crankshaft  92  to the sprocket  11 , the housing  10  rotates together with the crankshaft  92  in an advance (clockwise) direction X in  FIG. 3 . 
     As shown in  FIG. 3 , the shoe housing  12  has shoes  121 ,  122 ,  123 ,  124  (referred as  121 - 124 ) arranged in the rotational direction with a regular interval and projected inward in the radial direction from the inner circumference wall of the shoe housing  12 . The projection end surface of the shoe  121 - 124  has an arc-shape, and is slidably contact with an outer surface of a boss portion  25  of the vane rotor  20 . A seal member  125  is fitted to a concave portion of the shoe  121 - 124 . Accommodation chambers  100  are defined between the adjacent shoes  121 - 124  respectively. Each of the accommodation chambers  100  is surrounded by the side face of the corresponding shoe  121 - 124  and the inner circumference wall surface of the shoe housing  12 , and has a sector shape shown in  FIG. 3 . 
     The vane rotor  20  is accommodated in the housing  10 . As shown in  FIG. 1 , the axial end of the vane rotor  20  is slidingly contact with the wall surface of the sprocket  11  adjacent to the vane rotor  20 , and the other axial end of the vane rotor  20  is slidingly contact with the wall surface of the front plate  13  adjacent to the vane rotor  20 . As shown in  FIG. 3 , the vane rotor  20  has vanes  21 ,  22 ,  23 ,  24  (referred as  21 - 24 ) in addition to the boss portion  25 . 
     The vanes  21 - 24  are arranged in the rotational direction with a regular interval and projected from the outer circumference of the boss portion  25  to be accommodated in the accommodation chambers  100  respectively. The projection end surface of the vane  21 - 24  has an arc-shape, and is slidably contact with the inner surface of the shoe housing  12 . A seal member  26  is fitted to a concave portion defined in the projection end surface of the vane  21 - 24 . The vane  21 - 24  partitions the corresponding accommodation chamber  100 , thereby defining an advance oil pressure chamber  101 ,  102 ,  103 ,  104  (referred as  101 - 104 ) and a retard oil pressure chamber  105 ,  106 ,  107 ,  108  (referred as  105 - 108 ), which may correspond to a pressure chamber. 
     The advance oil pressure chambers  101 - 104  communicate with advance passages  111 ,  112 ,  113 ,  114  (referred as  111 - 114 ) defined in the sprocket  11 , respectively. The advance passages  111 - 114  communicate with an advance passage  62 , as shown in  FIG. 1 . 
     The retard oil pressure chambers  105 - 108  communicate with retard passages  201 ,  202 ,  203 ,  204  (referred as  201 - 204 ) defined in the vane rotor  20 , respectively. The retard passages  201 - 204  communicate with a retard passage  63 . 
     As shown in  FIG. 1 , a stopper piston  27  is accommodated to slidably reciprocate in the vane  21 . The stopper piston  27  is fitted to a fitting ring  117  arranged in the sprocket  11  by a biasing force of a helical compression spring  29 , thereby restraining the vane rotor  20  to the maximum advance position relative to the housing  10 . On the other hand, the stopper piston  27  is displaced to separate from the fitting ring  117  by at least one of an oil pressure force supplied from the retard oil pressure chamber  105  through a passage  221  and an oil pressure force supplied from the advance oil pressure chamber  101  through a passage  222  against the biasing force of the helical compression spring  29 , thereby allowing the vane rotor  20  to have relative rotation. 
     The bush  31  is fitted to the boss portion  25 , and is coaxially inserted to the inner circumference side of the front plate  13  in the rotatable state relative to the front plate  13 . The boss portion  25  of the vane rotor  20  is fixed to the camshaft  94  together with the bush  31  using a bolt  70 . The vane rotor  20  and the camshaft  94  rotate in the clockwise rotation in  FIG. 3 . The vane rotor  20  is rotatable relative to the housing  10  together with the camshaft  94 . 
     In  FIG. 3 , the advance direction X represents an advance rotation direction of the vane rotor  20  relative to the housing  10 , and a retard direction Y represents a retard rotation direction of the vane rotor  20  relative to the housing  10 .  FIG. 3  illustrates a state where the vane rotor  20  is located at the maximum advance position at which the vane rotor  20  is restricted from having rotation in the advance direction X and is allowed to have rotation in the retard direction Y relative to the housing  10 . 
     The bush  31  has a based cylindrical shape, and has a cylinder (pipe) part  311  and a bottom wall  312 . The cylinder part  311  has an opening part opposite from the bottom wall  312 , and a notch  36  is defined in the cylinder part  311  adjacent to the opening part. The bottom wall  312  has a through hole  35 , and integrally has an inside guide  38  projected toward the opening part from an edge of the through hole  35 . The inside guide  38  is formed coaxially with the bush  31 . As shown in  FIG. 4 , a positioning slot  381  is defined in the inside guide  38 . The bush  31  is fitted to the boss portion  25  of the vane rotor  20 , and is fixed with the bolt  70  which penetrates the through hole  35 . 
     The coiled spring  40  has a cylindrical shape, and includes a main part  41 , a first end  42  and a second end  43 . The first end  42  is formed on the inner side of the main part  41  in the radial direction, and the second end  43  is formed on the outer side of the main part  41  in the radial direction. The coiled spring  40  is accommodated in the bush  31 , and the first end  42  is engaged with the positioning slot  381  of the inside guide  38 . The second end  43  of the coiled spring  40  is taken out from the notch  36  of the bush  31  outward in the radial direction, and is engaged with a spring hook  131  fixed to the front plate  13 . Therefore, the first end  42  rotates with the vane rotor  20 , and the second end  43  rotates with the housing  10 . Moreover, the coiled spring  40  applies a force rotating the vane rotor  20  in the advance direction X relative to the housing  10  as a biasing torque. 
     The retainer  51  will be explained based on  FIGS. 4 and 5 . The retainer  51  has two projection parts  511  arranged in the circumference direction of the bush  31 . The projection part  511  projects from the inner wall of the cylinder part  311  of the bush  31  inward in the radial direction, and has a rib shape extending in the axial direction. In the present embodiment, the projection part  511  and the bush  31  are integrally formed. The projection part  511  has a contact part  512  extending in parallel with a rotation axis direction O. For example, the contact part  512  is defined by a ridge line portion of the projection part  511 . 
     When the coiled spring  40  is accommodated in the bush  31 , the outer wall of the main part  41  is contact with the contact part  512  of the retainer  51  and the inner wall of the cylinder part  311  of the bush  31 . That is, as shown in  FIG. 4 , the retainer  51  is contact with the coiled spring  40  at two points in the cross-sectional view of  FIG. 4 , for example, when the retainer  51  is projected on a plane surface perpendicular to the rotation axis direction O. In other words, the two contact parts  512  formed to extend in parallel with the rotation axis direction O are contact with the coiled spring  40 . 
     A controller  60  will be described with reference to  FIG. 1 . The controller  60  includes a switch valve  61  and an electronic control unit (ECU)  80 . The switch valve  61  is connected with the advance passage  62 , the retard passage  63 , a pump passage  64 , and drain passages  65  and  66 . An oil pump  67  is installed in the pump passage  64 . The oil pump  67  pumps oil corresponding to working fluid from an oil tank  68  through the upstream of the pump passage  64 , and discharges oil toward the switch valve  61  through the downstream of the pump passage  64 . Oil is discharged through the drain passage  65 ,  66  toward the oil tank  68  from the switch valve  61 . 
     The ECU  80  is constructed by an electric circuit such as microcomputer, and is electrically connected with plural sensors such as cam angle sensor  81 , crank angle sensor  82  in addition to the switch valve  61 . The ECU  80  computes a real phase and a target phase as to the engine phase of the camshaft  94  relative to the crankshaft  92 , based on the outputs of the sensors, and controls a drive electric current provided to the switch valve  61  according to the computed result so as to supply electricity to the switch valve  61 . 
     The electric power supplied to the switch valve  61  is controlled by the ECU  80 . The switch valve  61  is an electromagnetic spool type valve having a spool  613  which is moved in the axial direction according to balance between the driving force generated in a drive direction by activating an electromagnetic actuator  611  and a restoring force of a return spring  612  generated in an opposite direction opposite from the drive direction. The switch valve  61  switches the passage connection of the pump passage  64  and the drain passages  65  and  66  relative to the advance passage  62  and the retard passage  63  by the axial movement of the spool  613  according to the drive electric current provided to the actuator  611 . 
     Operations of the valve timing controller  1  will be described hereinafter. When the engine  91  is stopped, the stopper piston  27  is fitted to the fitting ring  117  at the maximum advance position due to the biasing force of the helical compression spring  29 . 
     At the engine startup time, the oil pump  67  is activated and the hydraulic fluid discharged from the oil pump  67  flows into the retard oil pressure chambers  105 - 108  via the retard passages  201 - 204 . As a result, the stopper piston  27  receives the oil pressure from the retard oil pressure chamber  105  through the passage  221 . When the oil pressure is raised to a predetermined pressure, the stopper piston  27  is separated from the fitting ring  117 . Thereby, the vane rotor  20  and the housing  10  become rotatable relative to each other. 
     A retard operation will be described. The ECU  80  controls the energizing of the switch valve  61 , thereby switching the connection state of the advance passage  62  and the retard passage  63  relative to the oil pump  67 . As a result, when the retard passage  63  communicates with the oil pump  67 , the oil pumped by the oil pump  67  flows into the retard oil pressure chambers  105 - 108  via the retard passage  63  and the retard passages  201 - 204 . Moreover, at this time, the oil of the advance oil pressure chambers  101 - 104  is discharged via the advance passages  111 - 114  and the advance passage  62  to the oil tank  68 . Thus, the oil pressure is impressed to the vanes  21 - 24  facing the retard oil pressure chambers  105 - 108 , and the vane rotor  20  has relative rotation in the retard direction Y relative to the housing  10 . 
     An advance operation will be described. When the advance passage  62  communicates with the oil pump  67 , the oil pumped by the oil pump  67  flows into the advance oil pressure chambers  101 - 104  via the advance passage  62  and the advance passages  111 - 114 . Moreover, at this time, the oil of the retard oil pressure chambers  105 - 108  is discharged via the retard passages  201 - 204  and the retard passage  63  to the oil tank  68 . Thus, the oil pressure is impressed to the vanes  21 - 24  facing the advance oil pressure chambers  101 - 104 , and the vane rotor  20  has relative rotation in the advance direction X relative to the housing  10 . 
     Thus, the passage to which the hydraulic fluid is supplied from the oil pump  67  is switched, thereby controlling the oil pressure of the advance oil pressure chambers  101 - 104  and the oil pressure of the retard oil pressure chambers  105 - 108 . Therefore, the relative rotation phase of the vane rotor  20  to the housing  10  is controlled so as to control the valve timing. In addition, at the valve timing control timing, the ECU  80  performs feedback control as to the energizing of the switch valve  61  in a manner that the actual valve timing of the exhaust valve  99  agrees with the target valve timing. Thus, the valve timing can be accurately controlled. 
     At the engine stop time, because the oil pump  67  is also stopped, the oil is no longer supplied to neither the advance passage  62  nor the retard passage  63 . Then, according to the restoring force of the coiled spring  40 , the vane rotor  20  has relative rotation to the maximum advance position, and the stopper piston  27  is fitted to the fitting ring  117 . 
     For example, when the engine  91  is abnormally stopped by an engine failure etc., there is a case where the next re-startup is conducted while the stopper piston  27  is not fitted to the fitting ring  117 . In such a case, the rotation phase is made to return to the default position at which the startup is possible by rotating the vane rotor  20  in response to the torque of the coiled spring  40  in the cranking period of the next re-startup time. 
     According to the first embodiment, the retainer  51  is in contact with the coiled spring  40  at the two points in the cross-section perpendicular to the rotation axis direction O. That is, the projection part  511  of the retainer  51  has the contact part  512  formed to extend in parallel with the rotation axis direction O. Thereby, when the coiled spring  40  contacts the contact part  51 , the center axis Os of the coiled spring  40  becomes parallel with the rotation axis direction O. Therefore, when the housing  10  and the vane rotor  20  rotate relative with each other, the torque of the coiled spring  40  is applied perpendicular to the rotation axis direction O. For this reason, the relative inclination between the housing  10  and the vane rotor  20  can be reduced in the rotation axis direction O, and wear between the housing  10  and the vane rotor  20  can be reduced. 
     In the present embodiment, the retainer  51  has a plurality of the projection parts  511 . That is, in the cross-section perpendicular to the rotation axis direction O, the retainer  51  is contact with the coiled spring  40  at the plural points. Thereby, because the projection parts  511  contact with the coiled spring  40  simultaneously, the effect correcting the posture of the coiled spring  40  can be raised so that the center axis Os of the coiled spring  40  and the rotation axis direction O become parallel with each other with more reliability. 
     In the present embodiment, the retainer  51  is arranged on the outer side of the coiled spring  40  in the radial direction. Therefore, a space can be secured on the inner side of the coiled spring  40  in the radial direction. Further, the bolt  70  can be attached easily on the inner side of the coiled spring  40  in the radial direction. 
     In the present embodiment, the retainer  51  and the bush  31  are integrally formed with each other. Thus, the number of components used for producing the valve timing controller  1  can be reduced. 
     Second Embodiment 
     A second embodiment will be described with reference to  FIGS. 6 and 7 .  FIG. 6  is a schematic cross-sectional view taken along a line VI-O-P-Q-VI in  FIG. 7 . In the second embodiment, only a different portion different from the first embodiment is explained and the explanation about the same composition as the first embodiment is omitted. The same portion has the same reference number as the first embodiment, and the explanation is omitted. 
     In the second embodiment, the bush  32  is formed into a cylindrical shape, and has a cylinder (pipe) part  321  and a bottom wall  322 . The cylinder part  321  has an engaging hole  37  on a side opposite from the bottom wall  322 . An approximately center part of the bottom wall  322  has the through hole  35 . 
     The retainer  52  has two projection parts  511  projected outward in the radial direction from the outer wall of the cylinder part  321  of the bush  32 . The projection parts  511  are arranged in the circumference direction, and each of the projection parts  511  has a rib shape extending in the axial direction. In the present embodiment, the projection part  511  and the bush  32  are integrally formed. The projection part  511  has the contact part  512  formed to extend in parallel with the rotation axis direction O. 
     In the second embodiment, the coiled spring  40  is arranged on the outer side of the bush  32  in the radial direction. The first end  42  of the coiled spring  40  is engaged with the engaging hole  37  of the bush  32 , and the second end  43  of the coiled spring  40  is engaged with the spring hook  131 . Moreover, the inner wall of the main part  41  of the coiled spring  40  is contact with the contact part  512  of the retainer  52 . 
     In the present embodiment, the retainer  52  is arranged on the inner side of the coiled spring  40  in the radial direction. Therefore, a space can be secured on the outer side of the coiled spring  40  in the radial direction. For example, when the covering  14  is attached to a position adjacent to the coiled spring  40 , the attaching of the covering  14  is not affected by the coiled spring  40 . 
     Third Embodiment 
     A third embodiment will be described with reference to  FIGS. 8 and 9 .  FIG. 9  is a schematic cross-sectional view taken along a line IX-O-P-Q-IX in  FIG. 8 . In the third embodiment, only a different portion different from the first embodiment is explained and the explanation about the same composition as the first embodiment is omitted. The same portion has the same reference number as the first embodiment, and the explanation is omitted. 
     In the third embodiment, the bush  33  is formed into the cylindrical shape having the cylinder part  331  and the bottom wall  332 . The notch  36  is defined in the cylinder part  331 , and the through hole  35  and the inside guide  38  are defined in the bottom wall  332 . 
     In the present embodiment, the retainer  53  has a bar shape, and is provided in the separate state separate from the bottom wall  332  of the bush  33 . Moreover, the number of the retainers  53  is two, and the retainers  53  are arranged in the circumference direction so as to contact with the side wall of the cylinder part  331 . 
     When the coiled spring  40  is accommodated in the bush  33 , the outer wall of the main part  41  is contact in the contact part  512  of the retainer  53  and the inner wall of the cylinder part  311  of the bush  33 . 
     In the present embodiment, the retainer  53  is provided separately from the bush  33 . Thus, the shape of the bush  33  can be simplified, and the bush  33  can be manufactured with fewer processes. 
     Fourth Embodiment 
     A fourth embodiment will be described with reference to  FIG. 10 . In the fourth embodiment, only a different portion different from the second embodiment is explained and the explanation about the same composition as the second embodiment is omitted. The same portion has the same reference number as the second embodiment, and the explanation is omitted. 
     The bush  32  is formed into the cylindrical shape, and has the cylinder part  321  and the bottom wall  322 . The cylinder part  321  has the engaging hole  37  on a side opposite from the bottom wall  322 . An approximately center part of the bottom wall  322  has the through hole  35 . 
     In the present embodiment, the retainer  53  is detachable from the front plate  13 . Moreover, two of the retainers  53  are arranged in the circumference direction of the cylinder part  321 . When the coiled spring  40  is provided to the bush  34 , the outer wall of the main part  41  is in contact with the contact part  512  of the retainer  53 . According to the fourth embodiment, the same advantages can be achieved as the second and third embodiments. 
     Other Embodiment 
     The valve timing controller is applied to the roller locker type power train system in the above embodiments. Alternatively, the valve timing controller may be applied to other type power train system such as direct compression type system. 
     The valve timing controller may be applied to the intake valve of the engine instead of the exhaust valve. 
     The vane rotor may be rotated with the crankshaft instead of the camshaft. In the above embodiments, in the cross-section perpendicular to the rotation axis direction, the retainer contacts the coiled spring at two points. Alternatively, the retainer may contact the coiled spring at one point, or three or more points in the cross-section perpendicular to the rotation axis direction. 
     The present application is not limited to the above embodiments. 
     Such changes and modifications are to be understood as being within the scope of the present disclosure as defined by the appended claims.