Patent Publication Number: US-9903235-B2

Title: Valve timing control apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Applications 2014-175497 and 2015-030006, filed on Aug. 29, 2014 and Feb. 18, 2015, respectively, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     This disclosure relates to a valve timing control apparatus that controls a relative rotational phase between a drive-side rotational member which is synchronized and rotates with a crankshaft of an internal combustion engine and a driven-side rotational member which integrally rotates with a camshaft. 
     BACKGROUND DISCUSSION 
     In recent years, a valve timing control apparatus that changes opening/closing timings of an intake valve and an exhaust valve in accordance with a driving condition of an internal combustion engine (hereinafter, referred to as an “engine”). The valve timing control apparatus has a configuration in which a relative rotational phase between a drive-side rotational member which is driven by a crankshaft and a driven-side rotational member which integrally rotates with a camshaft (hereinafter, simply referred to as a “relative rotational phase”) are changed such that the opening/closing timings of the intake and exhaust valves which are opened and closed in response to the rotation of the driven-side rotational member are changed. 
     In general, the optimum opening/closing timings of the intake and exhaust valves vary depending on the driving condition of the engine such as starting of the engine or traveling of a vehicle. At the starting of the engine, the relative rotational phase is restricted to an intermediate lock phase between the largest retardation angle phase and the largest advance angle phase such that the opening/closing timings of the intake and exhaust valves are set to have the optimum state for the starting of the engine. 
     JP 2013-100836 (Reference 1) discloses a valve timing control apparatus having an intermediate lock mechanism, in which opening/closing timings are restricted to an intermediate lock phase during stopping of an engine. Since both an advance angle chamber and a retardation angle chamber need to be promptly filled with oil after the engine is started, the advance angle chamber and the retardation angle chamber communicate with each other in a locked state such that the oil supplied to the advance angle chamber is also supplied to the retardation angle chamber through a communication path. At this time, an oil supply path of the retardation angle chamber is opened to a drain and air in a hydrostatic pressure chamber, which hinders the filling of the oil, is discharged such that the filling of the oil is enhanced. 
     However, in the valve timing control apparatus disclosed in Reference 1, since, when the engine is stopped, the advance angle chamber and the retardation angle chamber communicate with each other and one of the advance angle chamber and the retardation angle chamber communicates with the drain, oil in the hydrostatic pressure chamber is likely to be discharged. Therefore, when the engine is started, little amount of oil remains in the hydrostatic pressure chamber and it takes time to fill the hydrostatic pressure chamber with oil in this state. In addition, when the engine is abnormally stopped such as during a stall of the engine, it is difficult to set at a lock phase in some cases. If a sufficient amount of oil is not supplied to the hydrostatic pressure chamber, a driven-side rotational member that is likely to receive cam swinging torque is greatly oscillated with respect to a drive-side rotational member and, not only it is not possible for the engine to be started but there is also a concern that, since a vane section repeatedly comes into contact with a partition section inside the apparatus, noise will be produced or the drive-side rotational member will be deformed. 
     SUMMARY 
     Thus, a need exists for a valve timing control apparatus which is not suspectable to the drawback mentioned above. 
     An aspect of this disclosure is directed to a valve timing control apparatus including: a drive-side rotational member that synchronously rotates with a drive shaft of an internal combustion engine; a driven-side rotational member that is disposed inside the drive-side rotational member to be coaxial to the drive-side rotational member and that integrally rotates with a valve opening/closing camshaft of the internal combustion engine; a hydrostatic pressure chamber that is formed by partitioning a space between the drive-side rotational member and the driven-side rotational member; an advance angle chamber and a retardation angle chamber that are formed by dividing the hydrostatic pressure chamber with a dividing section provided on at least one of the drive-side rotational member and the driven-side rotational member; an intermediate lock mechanism that is able to selectively switch, through supplying and discharging of a hydraulic fluid, between a locked state in which a relative rotational phase of the driven-side rotational member to the drive-side rotational member is restricted to an intermediate lock phase between the largest advance angle phase and the largest retardation angle phase and an unlocked state in which the restriction to the intermediate lock phase is released; an advance angle flow path that allows the hydraulic fluid which is supplied to and discharged from the advance angle chamber to be circulated; a retardation angle flow path that allows the hydraulic fluid which is supplied to and discharged from the retardation angle chamber to be circulated; a control valve that has a spool which moves between a first position in a case where a power supply amount is zero and a second position different from the first position in a case of power supply; and a phase control unit that controls the control valve by controlling a power supply amount to the control valve and that supplies a hydraulic fluid to the advance angle chamber and the retardation angle chamber to shift the relative rotational phase. When the spool is disposed at one of the first position and the second position, the hydraulic fluid is set to be supplied to both the advance angle chamber and the retardation angle chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein: 
         FIG. 1  is a longitudinal sectional diagram showing a configuration of a valve timing control apparatus according to a first embodiment; 
         FIG. 2  is a sectional diagram taken along line II-II in  FIG. 1 ; 
         FIG. 3  shows a position of an OCV and a supply and discharge pattern of hydraulic oil; 
         FIG. 4  is an enlarged sectional diagram showing an operation state of the OCV in PA 1 ; 
         FIG. 5  is an enlarged sectional diagram showing an operation state of the OCV in PA 2 ; 
         FIG. 6  is an enlarged sectional diagram showing an operation state of the OCV in PL; 
         FIG. 7  is an enlarged sectional diagram showing an operation state of the OCV in PB 2 ; 
         FIG. 8  is an enlarged sectional diagram showing an operation state of the OCV in PB 1 ; 
         FIG. 9  shows a position of an OCV and a supply and discharge pattern of hydraulic oil according to a second embodiment; 
         FIG. 10  is an enlarged sectional diagram showing an operation state of the OCV in PB 1 ; 
         FIG. 11  is a diagram showing a section of a valve timing control apparatus and a control system according to a third embodiment; 
         FIG. 12  is a sectional diagram taken along line XII-XII in  FIG. 11 ; 
         FIG. 13  is a sectional diagram showing a state of a torsion spring in the largest retardation angle phase; 
         FIG. 14  is a sectional diagram showing a state of the torsion spring in an intermediate lock phase; 
         FIG. 15  is a sectional diagram showing a state of the torsion spring in the largest advance angle phase; 
         FIG. 16  is a sectional diagram showing a control valve in which a spool is disposed at a lock start position; 
         FIG. 17  is a sectional diagram showing the control valve in which the spool is disposed at a transition position; 
         FIG. 18  is a sectional diagram showing the control valve in which the spool is disposed at an advance angle position; 
         FIG. 19  is a sectional diagram showing the control valve in which the spool is disposed at a neutral position; 
         FIG. 20  is a sectional diagram showing the control valve in which the spool is disposed at a retardation angle position; 
         FIG. 21  is a diagram showing a relationship between supply and discharge of the control valve; 
         FIG. 22  is a diagram showing a relationship between supply and discharge of a control valve according to a modification example; 
         FIG. 23  is a graph showing a relationship between a relative rotational phase and a spring force; 
         FIG. 24  is a graph showing a relationship between a relative rotational phase and a spring force according to the modification example; 
         FIG. 25  is a chart showing a shift of a relative rotational phase or the like during engine stop control; 
         FIG. 26  is a chart showing a shift of a relative rotational phase or the like during engine stop control according to the modification example; 
         FIG. 27  is a chart showing a shift of a relative rotational phase or the like during engine start control; 
         FIG. 28  is a chart showing a shift of a relative rotational phase at a transition position during engine start control; 
         FIG. 29  is a sectional diagram showing a control valve in which a spool is disposed at a first retardation angle position according to a fourth embodiment; 
         FIG. 30  is a sectional diagram showing the control valve in which the spool is disposed at a second retardation angle position; 
         FIG. 31  is a sectional diagram showing the control valve in which the spool is disposed at a neutral position; 
         FIG. 32  is a sectional diagram showing the control valve in which the spool is disposed at a second advance angle position; 
         FIG. 33  is a sectional diagram showing the control valve in which the spool is disposed at a first advance angle position; 
         FIG. 34  is a sectional diagram showing the control valve in which the spool is disposed at an advance angle maintaining position; 
         FIG. 35  is a diagram showing a relationship between supply and discharge of the control valve; 
         FIG. 36  is a diagram showing a relationship between supply and discharge of a control valve according to another embodiment (a); and 
         FIG. 37  is a diagram showing a relationship between supply and discharge of a control valve according to still another embodiment (b). 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments disclosed here will be described based on the drawings. 
     First Embodiment 
     Hereinafter, a first embodiment that is achieved by applying this disclosure to a valve timing control apparatus on a side of an intake valve in an automobile engine (hereinafter, simply referred to as an “engine”) will be described in detail based on the drawings. In the following description of the embodiments, an engine E is an example of an internal combustion engine. 
     Entire Configuration 
     As shown in  FIG. 1 , a valve timing control apparatus  10  includes a housing  1  that synchronously rotates with a crankshaft C and an inner rotor  2  that is disposed on the inner side of the housing  1  to be coaxial to a shaft core X of the housing  1  and integrally rotates with a valve opening/closing camshaft  101  of the engine E. The camshaft  101  means a rotating shaft of a cam  104  which controls opening and closing of an intake valve  103  of the engine E and synchronously rotates with the inner rotor  2  and a fixing bolt  5 . The camshaft  101  is rotatably assembled into a cylinder head of the engine E. The crankshaft C is an example of a drive shaft, the housing  1  is an example of a drive-side rotational member, and the inner rotor  2  is an example of a driven-side rotational member. 
     An external thread  5   b  is formed at an end portion of the fixing bolt  5  on a side close to the camshaft  101 . The fixing bolt  5  is inserted at the center in a set-up state of the housing  1  and the inner rotor  2  and the external thread  5   b  of the fixing bolt  5  and an internal thread  101   a  of the camshaft  101  are screwed together. In this manner, the fixing bolt  5  is fixed to the camshaft  101  and the inner rotor  2  and the camshaft  101  are also fixed. 
     The housing  1  is configured through assembling, using a fastening bolt  16 , a front plate  11  which is disposed on a side opposite to a side on which the camshaft  101  is connected, an outer rotor  12  which is disposed over the external side of the inner rotor  2 , and a rear plate  13  which is integrally provided with a timing sprocket  15  and is disposed on the side on which the camshaft  101  is connected. The inner rotor  2  is accommodated in the housing  1  and a hydrostatic pressure chamber  4  to be described below is formed between the inner rotor  2  and the outer rotor  12 . The inner rotor  2  and the outer rotor  12  are configured to be relatively rotatable about the shaft core X. The timing sprocket  15  may not be provided on the rear plate  13  but may be provided on an outer peripheral section of the outer rotor  12 . 
     A torsion spring  70  disposed between the housing  1  and the camshaft  101  causes a bias force to be applied in a rotating direction S about the shaft core X and functions as a phase setting mechanism. The torsion spring  70  causes the bias force to be applied over the entire region of a relative rotational phase of the inner rotor  2  with respect to the housing  1  (hereinafter, simply referred to as the “relative rotational phase”). The torsion spring  70  may be configured to cause the bias force to be applied, for example, in a state in which the relative rotational phase is at the largest retardation angle to a state in which the relative rotational phase reaches a predetermined relative rotational phase on an advance angle side (intermediate lock phase P to be described below according to the present embodiment) and to cause the bias force not to be applied to a region in which the relative rotational phase is further on an advance angle side than the predetermined rotational phase. The torsion spring  70  may be disposed between the housing  1  and the inner rotor  2 . 
     When the crankshaft C rotates, a rotational drive force thereof is transmitted to the timing sprocket  15  through a power transmitting member  102  and the housing  1  is driven to rotate in the rotating direction S shown in  FIG. 2 . In response to the rotational drive of the housing  1 , the inner rotor  2  is rotatably driven in the rotating direction S such that the camshaft  101  rotates and the cam  104  provided on the camshaft  101  presses down the intake valve  103  of the engine E and the valve is opened. 
     As shown in  FIG. 2 , three protrusions  14  which protrude toward the inner side in a radial direction are formed in the outer rotor  12  and three vanes  21  are formed on the outer circumferential surface of the inner rotor  2 . In this manner, the hydrostatic pressure chamber  4  is formed between the inner rotor  2  and the outer rotor  12  and an advance angle chamber  41  and a retardation angle chamber  42  are formed. 
     Hydraulic oil as a hydraulic fluid is supplied to and discharged from the advance angle chamber  41  and the retardation angle chamber  42  or the supplying and discharging are blocked. In this manner, the oil pressure of the hydraulic oil acts on the vane  21  and the relative rotational phase is shifted in an advance angle direction or a retardation angle direction due to the oil pressure thereof, or an arbitrary phase is maintained. The advance angle direction means a direction in which the volume of the advance angle chamber  41  becomes greater and is a direction represented by arrow S 1  in  FIG. 2 . The retardation angle direction means a direction in which the volume of the retardation angle chamber  42  becomes greater and is a direction represented by arrow S 2  in  FIG. 2 . 
     As shown in  FIG. 2 , in the inner rotor  2 , an advance angle flow path  43  that communicates with the advance angle chamber  41 , a retardation angle flow path  44  that communicates with the retardation angle chamber  42 , an unlock flow path  45  through which hydraulic oil that is supplied to and discharged from an intermediate lock mechanism  8  to be described below is circulated, and a locking discharge flow path  46  are formed. The hydraulic oil is stored in an oil pan  61  and is supplied to each component by using an oil pump  62 . 
     Intermediate Lock Mechanism 
     The valve timing control apparatus  10  includes the intermediate lock mechanism  8  that restricts a shift of the relative rotational phase of the inner rotor  2  to the housing  1  and thereby restricts the relative rotational phase to the intermediate lock phase P between the largest advance angle phase and the largest retardation angle phase. The engine E is started in a state in which the relative rotational phase is restricted to the intermediate lock phase P. In this manner, even in a circumstance in which the oil pressure of the hydraulic oil is not stable immediately after the engine start, it is possible to appropriately maintain a rotational phase of the camshaft  101  with respect to a rotational phase of the crankshaft C and to realize stable rotation of the engine E. 
     As shown in  FIG. 2 , the intermediate lock mechanism  8  is configured to include a first lock member  81 , a first spring  82  as a bias mechanism, a second lock member  83 , a second spring  84  as the bias mechanism, a first recessed portion  85  as an engagement portion, and a second recessed portion  86  as the engagement portion. The intermediate lock mechanism  8  may be configured to include the first lock member  81  and the first spring  82 . 
     The first lock member  81  moves toward the inner rotor  2  due to a bias force of the first spring  82  and the second lock member  83  moves toward the inner rotor  2  due to a bias force of the second spring  84 . The first recessed portion  85  and the second recessed portion  86  are formed into a step shape such that the intermediate lock phase P is easily performed. 
     The unlock flow path  45  and the locking discharge flow path  46  are provided on the bottom of the first recessed portion  85  and the second recessed portion  86 . The unlock flow path  45  allows hydraulic oil that is supplied to and discharged from the first recessed portion  85  and the second recessed portion  86  to be circulated. Meanwhile, the locking discharge flow path  46  does not allow hydraulic oil that is supplied to the first recessed portion  85  and the second recessed portion  86  to be circulated, but allows hydraulic oil that is discharged from the first recessed portion  85  and the second recessed portion  86  to the outside of the valve timing control apparatus  10  to be circulated. 
     As shown in  FIG. 1 ,  FIG. 2 , and  FIG. 4  to  FIG. 8 , the locking discharge flow path  46  that is connected to the first recessed portion  85  and the second recessed portion  86  is configured to include a first discharge section  46   a  formed on the fixing bolt  5 , and a second discharge section  46   b  formed on the inner rotor  2 , which is connected to the first discharge section  46   a . The first discharge section  46   a  is connected to a sixth annular groove  47   m  formed on an inner circumferential surface of the fixing bolt  5 , which faces an accommodation space  5   a.    
     OCV 
     As shown in  FIG. 1 , according to the present embodiment, an oil control valve (OCV)  51  as a control valve is disposed on the inner side of the inner rotor  2  to be coaxial to the shaft core X. The OCV  51  is an example of a control valve. The OCV  51  is configured to include a spool  52 , a first valve spring  53   a  that biases the spool  52 , and an electromagnetic solenoid  54  that drives the spool  52  through changing a power supply amount. The OCV  51  causes a position of the spool  52  to be changed through changing the power supply amount to the electromagnetic solenoid  54 , performs control of supplying the hydraulic oil to the retardation angle chamber  42  and discharging the hydraulic oil from the advance angle chamber  41  or control of supplying the hydraulic oil to the advance angle chamber  41  and discharging the hydraulic oil from the retardation angle chamber  42 , and performs control of supplying and discharging the hydraulic oil to and from the intermediate lock mechanism  8  such that the relative rotational phase is shifted. A detailed description of the electromagnetic solenoid  54  is omitted because the known technology is applied thereto. 
     The spool  52  is configured to be accommodated in the accommodation space  5   a  that is a circular hole in a sectional view, which is formed parallel to a direction of the shaft core X from a head portion  5   c  that is an end portion of the fixing bolt  5  on a side apart from the camshaft  101  and to be slidable in the inside of the accommodation space  5   a  in the direction of the shaft core X. The spool  52  has a main discharge flow path  52   b  that is a circular bottomed hole in a sectional view, which is formed parallel to the direction of the shaft core X. The main discharge flow path  52   b  has a uniform inner diameter and is formed to have a step portion in the vicinity of an entrance. The main discharge flow path  52   b  may have an inner diameter that is equally increased to that on the discharge side thereof. 
     The first valve spring  53   a  is disposed deep inside the accommodation space  5   a  and continuously biases the spool  52  toward (in a leftward direction in  FIG. 1 ) the electromagnetic solenoid  54 . A stopper  55  attached to the accommodation space  5   a  prevents the spool  52  from slipping out from the accommodation space  5   a . One side of the first valve spring  53   a  is held in the step portion formed in the main discharge flow path  52   b . A partition  5   d  is inserted in a boundary between the accommodation space  5   a  and a third supply section  47   c  which is a bottomed hole having a small inner diameter, which is formed to be connected to the accommodation space  5   a  and thus, the partition  5   d  holds the other side of the first valve spring  53   a . When power is supplied to the electromagnetic solenoid  54 , a push pin  54   a  provided on the electromagnetic solenoid  54  presses an end portion  52   a  of the spool  52 . As a result, the spool  52  slides toward the camshaft  101  against the bias force of the first valve spring  53   a . The OCV  51  is configured to adjust a position of the spool  52  by changing the power supply amount to the electromagnetic solenoid  54  from zero to the maximum value. The power supply amount to the electromagnetic solenoid  54  is controlled by an electronic control unit (ECU)  90  (an example of a phase control unit). That is, the ECU  90  changes the power supply amount to the OCV  51  to control an operation of the OCV  51 . 
     The OCV  51  switches between supplying, discharging, and holding the hydraulic oil to and from, in the advance angle chamber  41  and the retardation angle chamber  42  depending on a position of the spool  52  and switches between supplying and discharging the hydraulic oil to and from the intermediate lock mechanism  8 . 
     Configuration of Oil Path 
     As shown in  FIG. 1 , the hydraulic oil stored in the oil pan  61  is sucked up by a mechanical oil pump  62  that drives by transmitting a rotational driving force of the crankshaft C and is circulated through a supply flow path  47  to be described below. The hydraulic oil circulated through the supply flow path  47  is supplied to the advance angle flow path  43 , the retardation angle flow path  44 , and the unlock flow path  45 , through the OCV  51 . 
     As shown in  FIG. 1  and  FIG. 4  to  FIG. 8 , the advance angle flow path  43  that is connected to the advance angle chamber  41  is configured to include a first advance angle section  43   a  which is a through-hole formed in the fixing bolt  5 , and a second advance angle section  43   b  formed in the inner rotor  2  to be connected to the first advance angle section  43   a . The retardation angle flow path  44  that is connected to the retardation angle chamber  42  is configured to include a first retardation angle section  44   a  which is a through-hole formed in the fixing bolt  5 , and a second retardation angle section  44   b  formed in the inner rotor  2  to be connected to the first retardation angle section  44   a . The unlock flow path  45  that is connected to the first recessed portion  85  and the second recessed portion  86  is configured to include a first unlock section  45   a  which is a through-hole formed in the fixing bolt  5 , and a second unlock section  45   b  formed in the inner rotor  2  to be connected to the first unlock section  45   a.    
     The supply flow path  47  is configured to include a first supply section  47   a  formed in the camshaft  101 , a second supply section  47   b  which is a space between the camshaft  101  and the fixing bolt  5 , a third supply section  47   c  formed in the fixing bolt  5 , a fourth supply section  47   d  formed around the fixing bolt  5 , a fifth supply section  47   e  formed in the inner rotor  2 , and two sixth supply sections  47   f  formed at different positions in the direction of the shaft core X of the fixing bolt  5  and the sections are connected to each other in this order. 
     The third supply section  47   c  is configured to have a bottomed hole formed in the fixing bolt  5  in the direction of the shaft core X and a plurality of holes which penetrate therethrough at two different places in the direction of the shaft core X to the outer circumference thereof. A check valve  48  is provided at an intermediate position of the bottomed hole, and a second valve spring  53   b  which is held by the partition  5   d  and the check valve  48  is biased in a direction in which the bottomed hole of the third supply section  47   c  is closed. 
     The fifth supply section  47   e  is configured to include a flow path which is formed in the inner rotor  2  in the direction of the shaft core X and which is closed at both ends, and three annular grooves formed at three different places in the direction of the shaft core X from the flow path to an inner circumferential surface toward the inner side in the radial direction. One of the three annular grooves faces the fourth supply section  47   d  and the remaining two annular grooves face the sixth supply sections  47   f , respectively. 
     As shown in order from left to right in  FIG. 4 , the sixth supply section  47   f , the first unlock section  45   a , the first advance angle section  43   a , the sixth supply section  47   f , and the first retardation angle section  44   a , which are through-holes formed in the fixing bolt  5 , are connected to a first annular groove  47   g , a second annular groove  47   h , a third annular groove  47   i , a fourth annular groove  47   j , and a fifth annular groove  47   k , respectively, which are annular grooves formed on the inner circumferential surface of the fixing bolt  5  which faces the accommodation space  5   a.    
     A seventh annular groove  52   c  and an eighth annular groove  52   d  are formed on an outer circumferential surface of the spool  52  to supply hydraulic oil that is circulated through the supply flow path  47  to one of the advance angle flow path  43 , the retardation angle flow path  44 , and the unlock flow path  45 . Further, a first through-hole  52   e  and a second through-hole  52   f  are formed in the spool  52  to discharge hydraulic oil, to the main discharge flow path  52   b , which is circulated through the advance angle flow path  43 , the retardation angle flow path  44 , and the unlock flow path  45 . The first through-hole  52   e  and the second through-hole  52   f  are connected to a ninth annular groove  52   h  and a tenth annular groove  52   i , respectively, which are annular grooves formed on the outer circumferential surface of the spool  52 . Further, a third through-hole  52   g  that discharges hydraulic oil that is circulated through the main discharge flow path  52   b  to the outside of the valve timing control apparatus  10  is formed. 
     Communication Path 
     An eleventh annular groove  52   j  (an example of a communication path) is formed at a position between the eighth annular groove  52   d  and the first through-hole  52   e . In the OCV  51 , in a case where the spool  52  is operated to move to a first retardation angle position PB 1  as a second position, the sixth supply section  47   f  and the third annular groove  47   i  communicate with each other through the eleventh annular groove  52   j . In this manner, the advance angle flow path  43  (advance angle chamber  41 ) enters into a state of communicating with the retardation angle flow path  44  (retardation angle chamber  42 ). That is, in the first retardation angle position PB 1 , the eleventh annular groove  52   j  allows hydraulic oil to be circulated through the advance angle chamber  41  and the retardation angle chamber  42 . 
     Outline of Operational Mode of OCV 
     As shown in  FIG. 4  to  FIG. 8 , the spool  52  of the OCV  51  of the embodiment is configured to be operated to move to five positions of the first advance angle position PA 1 , a second advance angle position PA 2 , a phase maintaining position PL, a second retardation angle position PB 2 , and the first retardation angle position PB 1 . In addition,  FIG. 3  shows supply and discharge patterns in these positions. 
     In this configuration, the OCV  51  moves to the second advance angle position PA 2 , the phase maintaining position PL, and the second retardation angle position PB 2 , which means that the valve enters into an unlocked state in which a fluid is supplied to the unlock flow path  45  and the supplying and discharging of hydraulic oil to and from the advance angle flow path  43  and the retardation angle flow path  44  are controlled. In addition, at the first advance angle position PA 1  and the first retardation angle position PB 1 , a locked state is performed in which the discharging of the hydraulic oil from the unlock flow path  45  and the locking discharge flow path  46  and the supplying of the hydraulic oil to one of the advance angle flow path  43  and the retardation angle flow path  44  are controlled. 
     In the OCV  51 , in a state in which no power is supplied to the electromagnetic solenoid  54 , the spool  52  is disposed at the first advance angle position PA 1  and is switched to the second advance angle position PA 2 , the phase maintaining position PL, the second retardation angle position PB 2 , and the first retardation angle position PB 1  by increasing power supply to the electromagnetic solenoid  54  by predetermined values, respectively, in this order. 
     (1) First Advance Angle Position 
     As shown in  FIG. 4 , when a current supplied to the electromagnetic solenoid  54  is zero (power supply amount is zero), the OCV  51  is disposed at the first advance angle position PA 1  and the spool  52  comes into contact with the stopper  55  due to the bias force of the first valve spring  53   a  and is positioned on the farthest left side. In this state, when the hydraulic oil is supplied to the supply flow path  47 , the hydraulic oil is circulated through the first supply section  47   a , the second supply section  47   b , and the third supply section  47   c . When hydraulic pressure acting on the check valve  48  becomes higher in the third supply section  47   c  than a bias force of the second valve spring  53   b , the check valve  48  is opened. Thus, the hydraulic oil is circulated through the fourth supply section  47   d , the fifth supply section  47   e , and the sixth supply sections  47   f , reaches the seventh annular groove  52   c  through the first annular groove  47   g , and reaches the eighth annular groove  52   d  through the fourth annular groove  47   j.    
     The seventh annular groove  52   c  is not connected to any flow path and thus, the hydraulic oil does not flow from there any farther. Since the eighth annular groove  52   d  is connected to the advance angle flow path  43  through the third annular groove  47   i , the hydraulic oil is circulated through the advance angle flow path  43  and is supplied to the advance angle chamber  41 . That is, the advance angle flow path  43  has a supply state. The retardation angle flow path  44  is connected to the second through-hole  52   f  through the fifth annular groove  47   k  and the tenth annular groove  52   i  and the unlock flow path  45  is connected to the first through-hole  52   e  through the second annular groove  47   h  and the ninth annular groove  52   h . Therefore, the hydraulic oil in the retardation angle chamber  42 , the first recessed portion  85 , and the second recessed portion  86  is discharged from the main discharge flow path  52   b  through the third through-hole  52   g  to the outside of the valve timing control apparatus  10 . That is, both the retardation angle flow path  44  and the unlock flow path  45  are in a drain state. Thus, as shown in  FIG. 3 , at the first advance angle position PA 1 , the hydraulic oil is discharged from the intermediate lock mechanism  8  (the first recessed portion  85  and the second recessed portion  86 ) and the retardation angle chamber  42  and the advance angle chamber  41  enters into a state in which hydraulic oil is supplied thereto, which means a “lock at an intermediate lock phase P due to an advance angle operation”. 
     (2) Second Advance Angle Position 
     As shown in  FIG. 5 , when power starts to be supplied to the electromagnetic solenoid  54 , the OCV  51  is disposed at the second advance angle position PA 2  in  FIG. 3  and the spool  52  slightly moves to the right side from the first advance angle position PA 1 . In this state, when the hydraulic oil is supplied to the supply flow path  47 , the hydraulic oil reaches the seventh annular groove  52   c  and the eighth annular groove  52   d . Since the seventh annular groove  52   c  is connected to the unlock flow path  45  through the second annular groove  47   h , the hydraulic oil is circulated through the unlock flow path  45  and is supplied to the first recessed portion  85  and the second recessed portion  86 . That is, the unlock flow path  45  is switched to a supply state. When the hydraulic pressure of the supplied hydraulic oil is higher than the bias force of the first spring  82  and the second spring  84 , the first lock member  81  and the second lock member  83  are separated from the first recessed portion  85  and the second recessed portion  86 , respectively, and enter into the unlocked state.  FIG. 5  shows a state immediately after switching from the first advance angle position PA 1  to the second advance angle position PA 2 . 
     Since the eighth annular groove  52   d  is continuously connected to the advance angle flow path  43 , the hydraulic oil is circulated through the advance angle flow path  43  and is supplied to the advance angle chamber  41 . That is, the advance angle flow path  43  is in a supply state. Since the retardation angle flow path  44  is continuously connected to the second through-hole  52   f , the hydraulic oil in the retardation angle chamber  42  is discharged from the main discharge flow path  52   b  through the third through-hole  52   g  to the outside of the valve timing control apparatus  10 . That is, the retardation angle flow path  44  is in the drain state. Thus, as shown in  FIG. 3 , at the second advance angle position PA 2 , the hydraulic oil is supplied to the intermediate lock mechanism  8  (the first recessed portion  85  and the second recessed portion  86 ) and the advance angle chamber  41  and hydraulic oil is discharged from the retardation angle chamber  42  such that the relative rotational phase is shifted to the advance angle direction S 1 , which means an “advance angle operation in the unlocked state”. 
     (3) Phase Maintaining Position 
     As shown in  FIG. 6 , when a power supply amount to the electromagnetic solenoid  54  is increased and the OCV  51  is disposed at the phase maintaining position PL in  FIG. 3 , the spool  52  slightly moves to the right side from the second advance angle position PA 2 . In this state, when the hydraulic oil is supplied to the supply flow path  47 , the hydraulic oil reaches the seventh annular groove  52   c  and the eighth annular groove  52   d . Since the seventh annular groove  52   c  is continuously connected to the unlock flow path  45 , the hydraulic oil is circulated through the unlock flow path  45  and is supplied to the first recessed portion  85  and the second recessed portion  86 . That is, the unlock flow path  45  is in the supply state. Thus, even at the phase maintaining position PL, the unlocked state is continuously maintained from the second advance angle position PA 2 .  FIG. 6  shows a state of the vicinity of the center of the phase maintaining position PL shown in  FIG. 3 . 
     The eighth annular groove  52   d  is not connected to any flow path and thus, the hydraulic oil does not flow from there any farther. That is, the hydraulic oil is not supplied to the advance angle flow path  43  and the retardation angle flow path  44 . In addition, since the advance angle flow path  43  and the retardation angle flow path  44  are not connected to any flow path of the first through-hole  52   e  or the second through-hole  52   f , the hydraulic oil in the advance angle chamber  41  and the retardation angle chamber  42  is not discharged to the outside of the valve timing control apparatus  10 . Accordingly, when the OCV  51  is controlled to the phase maintaining position PL, the hydraulic oil is neither supplied to nor discharged from the advance angle chamber  41  and the retardation angle chamber  42 . Therefore, the inner rotor  2  maintains the relative rotational phase at that time and does not move in the advance angle direction S 1  or in the retardation angle direction S 2 . Thus, as shown in  FIG. 3 , at the phase maintaining position PL, the hydraulic oil is supplied to the intermediate lock mechanism  8  (the first recessed portion  85  and the second recessed portion  86 ), but the hydraulic oil is neither supplied to nor discharged from the advance angle chamber  41  and the retardation angle chamber  42  such that the relative rotational phase is maintained, which means an “intermediate phase maintenance”. 
     (4) Second Retardation Angle Position 
     As shown in  FIG. 7 , when a power supply amount to the electromagnetic solenoid  54  is increased and the OCV  51  is disposed at the second retardation angle position PB 2  in  FIG. 3 , the spool  52  slightly moves to the right side from the phase maintaining position PL. In this state, when the hydraulic oil is supplied to the supply flow path  47 , the hydraulic oil reaches the seventh annular groove  52   c  and the eighth annular groove  52   d . Since the seventh annular groove  52   c  is continuously connected to the unlock flow path  45 , the hydraulic oil is circulated through the unlock flow path  45  and is supplied to the first recessed portion  85  and the second recessed portion  86 . That is, the unlock flow path  45  is in the supply state. Thus, even at the second retardation angle position PB 2 , the unlocked state is continuously maintained from the second advance angle position PA 2  and the phase maintaining position PL.  FIG. 7  shows a state immediately after switching from the phase maintaining position PL to the second retardation angle position PB 2 . 
     Since, at the second retardation angle position PB 2 , the eighth annular groove  52   d  is connected to the retardation angle flow path  44  through the fifth annular groove  47   k , the hydraulic oil is circulated through the retardation angle flow path  44  and is supplied to the retardation angle chamber  42 . That is, the retardation angle flow path  44  is in the supply state. Since the advance angle flow path  43  is connected to the first through-hole  52   e  through the third annular groove  47   i  and the ninth annular groove  52   h , the hydraulic oil in the advance angle chamber  41  is discharged from the main discharge flow path  52   b  through the third through-hole  52   g  to the outside of the valve timing control apparatus  10 . That is, the advance angle flow path  43  is in the drain state. Accordingly, as shown in  FIG. 3 , at the second retardation angle position PB 2 , the hydraulic oil is supplied to the intermediate lock mechanism  8  (the first recessed portion  85  and the second recessed portion  86 ) and the retardation angle chamber  42  and hydraulic oil is discharged from the advance angle chamber  41  such that the relative rotational phase is shifted to the retardation angle direction S 2 , which means a “retardation angle operation in an unlocked state”. 
     (5) First Retardation Angle Position 
     A power supply amount to the electromagnetic solenoid  54  is increased at the second retardation angle position PB 2  and thereby, the spool  52  further moves to the right side from the first retardation angle position PB 1  ( FIG. 8 ). In this state, when the hydraulic oil is supplied to the supply flow path  47 , the hydraulic oil discharged from the advance angle chamber  41  is circulated through the advance angle flow path  43 . The hydraulic oil which is circulated through the retardation angle flow path  44  is supplied to the retardation angle chamber  42 . At this time, the advance angle chamber  41  and the retardation angle chamber  42  communicate with each other through the eleventh annular groove  52   j  (an example of the communication path). The hydraulic oil which is circulated through the unlock flow path  45  is continuously circulated through the seventh annular groove  52   c , the seventh annular groove  52   c  does not face the first annular groove  47   g , and the hydraulic oil does not flow through the unlock flow path  45 . 
     At the first retardation angle position PB 1 , the hydraulic oil in the intermediate lock mechanism  8  is circulated through the locking discharge flow path  46  alone, is discharged to the main discharge flow path  52   b  from the second through-hole  52   f  through the sixth annular groove  47   m  and the tenth annular groove  52   i  and is discharged to the outside of the valve timing control apparatus  10  through the third through-hole  52   g . Hereinafter, at the first retardation angle position PB 1  according to the present embodiment, the locking discharge flow path  46 , the sixth annular groove  47   m , the tenth annular groove  52   i , and the second through-hole  52   f  are collectively referred to as the second discharge flow path. 
     As shown in  FIG. 3 , at the first retardation angle position PB 1 , the hydraulic oil is discharged from the intermediate lock mechanism  8  (the first recessed portion  85  and the second recessed portion  86 ) and the advance angle chamber  41  and hydraulic oil is supplied to the retardation angle chamber  42 , which means a “lock at the intermediate lock phase P due to the retardation angle operation”. 
     Regarding Operation of OCV when Engine is Stopped 
     In a state in which the engine E is stopped, power is not supplied to the electromagnetic solenoid  54  and thus, the spool  52  of the OCV  51  is disposed at the first advance angle position PA 1 . That is, when a current supplied to the OCV  51  is zero, the intermediate lock mechanism  8  enters into the locked state, the advance angle chamber  41  and the retardation angle chamber  42  do not communicate with each other, hydraulic oil is supplied to one (advance angle chamber  41  according to the present embodiment) of the advance angle chamber  41  and the retardation angle chamber  42 , and the hydraulic oil is discharged from the other chamber (retardation angle chamber  42  according to the present embodiment). Thus, when power is not supplied to the OCV  51  after the engine is stopped, it is possible to cause a certain amount of hydraulic oil to remain in one of the advance angle chamber  41  and the retardation angle chamber  42 . 
     In this manner, a certain amount of the hydraulic oil is held in the fluid pressure chamber  4 , cam swinging torque is alleviated by the hydraulic oil even though the engine E starts not from the locked state but from the intermediate phase. In this manner, it is possible to avoid a defect of deforming of the housing  1  or the inner rotor  2  by being contact with the housing  1  in the fluid pressure chamber  4  formed by partitioning. 
     Regarding Operation of OCV when Engine is Started 
     When an ignition turns on, for example, at the time of starting the engine E, the ECU  90  instructs the maximum power supply to the electromagnetic solenoid  54 . In this manner, the spool  52  of the OCV  51  moves to the first retardation angle position PB 1  and the advance angle chamber  41  and the retardation angle chamber  42  communicate with each other through the eleventh annular groove  52   j . That is, when a current is supplied to the OCV  51 , the intermediate lock mechanism  8  enters into the locked state, the advance angle chamber  41  and the retardation angle chamber  42  communicate with each other through the eleventh annular groove  52   j  formed in the spool  52 , and a part of hydraulic oil is supplied to one (retardation angle chamber  42  according to the present embodiment) of the advance angle chamber  41  and the retardation angle chamber  42 , and a part of the hydraulic oil is supplied to the other chamber (advance angle chamber  41  according to the present embodiment) through the eleventh annular groove  52   j . In addition, the eleventh annular groove  52   j  is connected to the first through-hole  52   e  through the advance angle flow path  43 . Therefore, a part of the hydraulic oil which is supplied to the retardation angle chamber  42  and flows through the eleventh annular groove  52   j  is discharged from the main discharge flow path  52   b  through the third through-hole  52   g  to the outside of the valve timing control apparatus  10 . 
     In this manner, power is supplied to the OCV  51  and thereby, the advance angle chamber  41  and the retardation angle chamber  42  communicate with each other before cranking is started. Accordingly, since the hydraulic oil supplied to one of the advance angle chamber  41  and the retardation angle chamber  42  is also supplied to the other chamber of the advance angle chamber  41  and the retardation angle chamber  42  through the eleventh annular groove  52   j , it is possible to rapidly fill the advance angle chamber  41  and the retardation angle chamber  42  with the hydraulic oil when the engine E is started. 
     Second Embodiment 
     Next, a second embodiment will be described with reference to  FIG. 9  and  FIG. 10 . According to the present embodiment, only a part that is different from the first embodiment in  FIG. 1  to  FIG. 8  will be described. The present embodiment is configured such that the discharging of the hydraulic oil is controlled at the first retardation angle position PB 1  shown in  FIG. 9 . Specifically, the hydraulic oil is discharged from the advance angle chamber  41  at the first retardation angle position PB 1 -( 2 ), the hydraulic oil is supplied to the retardation angle chamber  42 , and the hydraulic oil is discharged from the first recessed portion  85  and the second recessed portion  86 . For example, the lock is unlocked at the second advance angle position PA 2  such that, when switching to the locked state from a state in which the relative rotational phase moves in the direction toward the advance angle from the intermediate lock phase P is performed, the hydraulic oil is discharged from the advance angle chamber  41  and the hydraulic oil is supplied only to the retardation angle chamber  42  due to the providing of the first retardation angle position PB 1 -( 2 ). Thus, it is possible to shift the relative rotational phase due to differential pressure between the advance angle chamber  41  and the retardation angle chamber  42  and it is possible to move the lock members  81  and  82  to the corresponding first recessed portion  85  and the second recessed portion  86  such that it is possible to reliably perform locking by further discharging the hydraulic oil from the first recessed portion  85  and the second recessed portion  86 . 
     Next, unique effects achieved when the spool  52  moves from the first retardation angle position PB 1 -( 1 ) corresponding to  FIG. 8  to the first retardation angle position PB 1 -( 2 ) corresponding to  FIG. 10  will be described. According to the present embodiment, the power supply amount to the OCV  51  is changed by the ECU  90  and the spool  52  is caused to move from a communication position ( FIG. 8 ) at which the advance angle chamber  41  and the retardation angle chamber  42  communicate with each other through the eleventh annular groove  52   j , to a non-communication position ( FIG. 10 ).  FIG. 9  shows an operational configuration of the OCV  51  according to the present embodiment when the position of the spool  52  is shifted to the PA 1  to PB 1  in response to the power supply amount to the electromagnetic solenoid  54 . 
     Specifically, the power supply amount to the electromagnetic solenoid  54  is caused to be reduced by the ECU  90  such that the spool  52  at the first retardation angle position PB 1  is caused to move in a state shown in  FIG. 8  to the left side ( FIG. 10 ). In this manner, the supply flow path  47  and the advance angle flow path  43  (drain) have a blocked state of not communicating with each other through the eleventh annular groove  52   j  and the hydraulic oil supplied from the supply flow path  47  is not discharged. In this manner, it is possible to efficiently use the hydraulic oil that is supplied to the fluid pressure chamber  4 . 
     For example, the ECU  90  causes the spool  52  to move to the non-communication position after the spool  52  moves to the communication position and a predetermined period of time elapses. In this manner, it is possible to control the OCV  51  only by setting a period of time for which the fluid pressure chamber  4  is completely filled with the hydraulic oil, as the predetermined time, and it is possible to simplify the configuration of the ECU  90 . 
     The period of time which is taken for completely filling the fluid pressure chamber  4  with the hydraulic oil is changed based on a temperature of the hydraulic oil in the fluid pressure chamber  4  or a water temperature inside the engine E. Therefore, the predetermined period of time described above may be determined based on the temperature of the hydraulic oil in the fluid pressure chamber  4  or the water temperature inside the engine E. In this manner, since the predetermined period of time is set by the ECU  90  with high accuracy, it is possible to suppress the discharge of the hydraulic oil. 
     Modification Example of Second Embodiment 
     (1) According to the second embodiment, an example in which the spool  52  of the OCV  51  is caused to move to the non-communication position based on a period of time which elapses after the spool moves to the communication position is described. Instead, the spool  52  may be caused to move to the non-communication position ( FIG. 10 ) from the communication position ( FIG. 8 ) based on a pressure change in the fluid pressure chamber  4 . 
     When the fluid pressure chamber  4  is supplied with a hydraulic fluid and is filled with the hydraulic oil, a pressure in the fluid pressure chamber  4  increases to a predetermined threshold value or greater. Using this, according to the present embodiment, the ECU  90  causes the spool  52  to move to the non-communication position from the communication position when the pressure in the fluid pressure chamber  4  becomes the predetermined threshold value or greater. In this manner, it is possible to cause the spool  52  to move to the non-communication position immediately after the fluid pressure chamber  4  is completely filled with the hydraulic oil and it is possible to effectively suppress wasteful discharge of the hydraulic oil. 
     (2) According to the above embodiment, an example is described, in which the spool  52  has an annular groove (eleventh annular groove  52   j ) formed as the communication path through which the advance angle chamber  41  and the retardation angle chamber  42  communicate with each other. However, the annular groove may not be formed but a groove portion may be formed partially in a circumferential direction as long as the advance angle chamber  41  and the retardation angle chamber  42  communicate with each other. Alternatively, a through-hole as a communication path may be formed in the spool  52 . 
     (3) According to the above embodiment, a configuration is described, in which the unlock flow path  45  and the locking discharge flow path  46  are provided as flow paths that communicate with the intermediate lock mechanism  8 . However, a configuration may be employed, in which only the unlock flow path  45  is provided as the flow path that communicates with the intermediate lock mechanism  8 . 
     (4) According to the above embodiment, an example is described, in which the OCV  51  is configured to enter into the locked state of the advance angle control when the power supply amount is zero and a locked state of the retardation angle control when the power supply amount becomes the maximum value. However, the OCV  51  may be configured to enter into the locked state of the retardation angle control when the power supply amount is zero and to enter into the locked state of the advance angle control when the power supply amount becomes the maximum value. 
     Third Embodiment 
     Basic Configuration 
     As shown in  FIG. 11  and  FIG. 12 , an internal combustion engine control system is configured to include a valve timing control apparatus A that sets an opening/closing timing of an intake valve  202  of the engine E as the internal combustion engine, and an engine control unit (functioning as an example of a control unit, that is an ECU)  240  that controls the engine E. 
     The engine E shown in  FIG. 11  is provided in a vehicle such as an automobile. The engine E is configured to include a crankshaft  201  as the drive shaft, to accommodate a piston  204  inside a cylinder bore of a cylinder block  203 , and to be a four-cycle type in which the piston  204  and the crankshaft  201  are connected using a connecting rod  205 . In the intake valve  202 , an opening/closing operation is performed by rotating an intake camshaft  206 . 
     The engine E includes a starter motor M that transmits drive torque to the crankshaft  201  when starting, a fuel control unit  207  that controls ejection of a fuel to an intake port or a fuel chamber, an ignition control unit  208  that controls ignition by spark plug (not shown), and a shaft sensor RS that detects a rotating angle and a rotating speed of the crankshaft  201 . 
     The valve timing control apparatus A is configured to include a valve timing control unit  210  and a control valve V. The valve timing control unit  210  includes a phase detecting sensor  246  that is disposed coaxially to the shaft core X of the outer rotor  211  and the inner rotor  212  and that detects a relative rotational phase of the inner rotor  212  to the outer rotor  211 . Hereinafter, the relative rotational phase of the inner rotor  212  to the outer rotor  211  is described as the relative rotational phase. 
     In the valve timing control unit  210 , a timing chain  209  is wound over an output sprocket  201 S provided on the crankshaft  201  of the engine E and also over a timing sprocket  215 S of the outer rotor  211  and thereby, the outer rotor  211  synchronously rotates with the crankshaft  201 . Although not shown in the drawings, a device having the same configuration as the valve timing control unit  210  is also included at the front end of a discharge camshaft on the discharge side and torque from the timing chain  209  is transmitted also to the device. In addition, the valve timing control unit  210  rotates in a drive-rotating direction S due to a drive force from the timing chain  209 . 
     In addition, a hydraulic pump Q that is driven by the drive force of the crankshaft  201  of the engine E is provided. The hydraulic pump Q sends out the lubricant oil of the engine E as the hydraulic oil (an example of the hydraulic fluid) and the hydraulic oil is supplied to the valve timing control unit  210  through the control valve V. 
     The ECU  240  includes an engine control section  241  and a phase control section  242 . The engine control section  241  controls the starter motor M, the fuel control unit  207 , and the ignition control unit  208  to perform start and stop of the engine E. The phase control section  242  controls the relative rotational phase and a lock mechanism L (an example of the intermediate lock mechanism) of the valve timing control unit  210 . A control configuration and a control aspect related to the ECU  240  will be described below. 
     Valve Timing Control Unit 
     The valve timing control unit  210  includes the outer rotor  211  as a drive-side rotational member that synchronously rotates with the crankshaft  201  of the engine E, and the inner rotor  212  as a driven-side rotational member that connects the intake valve  202  of the fuel chamber of the engine E to the intake camshaft  206  which is opened and closed by a connection bolt  213 . The inner rotor  212  is fit inside the outer rotor  211  such that the shaft core of the outer rotor  211  and the shaft core of the inner rotor  212  are coaxial and thus, the inner rotor  212  and the outer rotor  211  are disposed in a relatively rotatable manner with the shaft core X as the center. In this configuration, the shaft core X is a rotating shaft core of the intake camshaft  206  and a rotating shaft core of the outer rotor  211  and the inner rotor  212 . 
     The outer rotor  211  and the inner rotor  212  are fastened using a fastening bolt  216  in a state of being interposed between a front plate  214  and a rear plate  215 . The timing sprocket  215 S is formed on the outer periphery of the rear plate  215 . The center portion of the inner rotor  212  is disposed in a state of penetrating an opening formed at the center of the rear plate  215  and the intake camshaft  206  is connected to the end portion of the inner rotor  212  on the rear plate  215  side. 
     According to the present embodiment, a configuration in which the valve timing control unit  210  is provided to the intake camshaft  206  is described; however, the valve timing control unit  210  may be provided to the discharge camshaft or the valve timing control units  210  may be provided to both the intake camshaft  206  and the discharge camshaft. 
     A plurality of protrusions  211 T which protrude toward the inner side in the radial direction are integrally formed with the outer rotor  211  in the direction of the shaft core X. The inner rotor  212  is cylindrically formed to have an outer circumference which comes into close contact with the protruding ends of the plurality of protrusions  211 T. In this manner, a plurality of fluid pressure chambers R are formed on the outer circumferential side of the inner rotor  212  at intermediate positions between the protrusions  211 T adjacent in the rotating direction. A plurality of vanes  217  as dividing portions which protrude outwardly are provided on the outer circumference of the inner rotor  212 . 
     The fluid pressure chamber R forms an advance angle chamber Ra and a retardation angle chamber Rb through dividing by the vane  217 . According to the present embodiment, the vane  217  that is formed to be integral with the inner rotor  212  and protrudes to the outer side from the outer circumference of the inner rotor  212  is described; however, a plate-shaped material may be used as the vane  217  or the vane  217  may be configured to be fitted and supported on the outer circumference of the inner rotor  212 . 
     A direction in which the inner rotor  212  rotates in the same direction as the drive-rotating direction S with respect to the outer rotor  211  is referred to as the advance angle direction S 1  and a direction opposite to the advance angle direction S 1  is referred to as a retardation angle direction S 2 . In the valve timing control unit  210 , the relative rotational phase is shifted to the advance angle direction S 1  by supplying the hydraulic oil (an example of a fluid) to the advance angle chamber Ra and the intake timing occurs at an earlier stage. Conversely, the relative rotational phase is shifted to the retardation angle direction S 2  by supplying the hydraulic oil to the retardation angle chamber Rb and the intake timing is delayed. 
     Valve Timing Control Unit: Lock Mechanism 
     The valve timing control unit  210  includes the lock mechanism L in which the relative rotational phase is maintained in the intermediate lock phase P shown in  FIG. 12 . The lock mechanism L is configured to include a pair of lock members  225  which are provided to the protrusions  211 T of the outer rotor  211 , respectively, in an extendable and retractable way, a lock spring  226  as a bias mechanism which biases the lock member  225  in the protruding direction, and a recessed intermediate lock portion  227  (an example of an engagement portion) which is formed on the outer circumference of the inner rotor  212  such that the lock member  225  is fitted thereto. The intermediate lock phase P means that the engine E is smoothly started in a cold state in which a temperature of a fuel chamber is lowered to the outside air temperature. 
     A ratcheting step portion  227   a  is formed in the recessed intermediate lock portion  227  to have a shape of a groove shallower than the recessed intermediate lock portion  227  such that the relative rotational phase is continuous in the retardation angle direction S 2  with the intermediate lock phase P as a reference. In this manner, in a case where the relative rotational phase is shifted from the largest retardation angle phase toward the intermediate lock phase P, one lock member  225  engages with the recessed intermediate lock portion  227  such that the shift of the relative rotational phase is prevented. Then, the other lock member  225  engages with the step portion  227   a  and further, progress to a state of being fitted to the recessed intermediate lock portion  227  is reliably made in response to a shift of the relative rotational phase in the engagement state. 
     The step portion  227   a  may be set at a position to be continuous from the recessed intermediate lock portion  227  in the advance angle direction S 1  and may be set at two predetermined positions to be continuous in the respective advance angle direction S 1  and retardation angle direction S 2 . In addition, the lock mechanism L may be configured to include one lock member  225  and one recessed intermediate lock portion  227 . 
     Valve Timing Control Unit: Torsion Spring 
     As shown in  FIG. 11  and  FIG. 13  to  FIG. 15 , a torsion spring  218  is provided as a phase setting mechanism that causes a bias force to be applied over the inner rotor  212  and the front plate  214  in a state in which the relative rotational phase of the inner rotor  212  to the outer rotor  211  (hereinafter, referred to as the relative rotational phase) becomes the largest retardation angle phase to a state in which the relative rotational phase is disposed at the intermediate lock phase P. 
     During an operation of the engine E, a reactive force to the rotation of the intake camshaft  206  acts on the intake camshaft  206  in the retardation angle direction S 2  and the advance angle direction S 1 . The reactive force is intermittently generated to be used as cam swinging torque and thus, in the present embodiment, an average value of the reactive forces (cam swinging torque) is described as a retardation angle actuating force. 
     A biasing direction of the torsion spring  218  is set to cause the bias force to be applied in a direction (advance angle direction S 1 ) opposite to a direction of the average value of the reactive force (cam swinging torque) which acts on the intake camshaft  206 . As shown in the graph in  FIG. 23 , the bias force of the torsion spring  218  is set to a value greater than the retardation angle actuating force (average value of the reactive forces) in a region of the relative rotational phase between the largest retardation angle phase to the intermediate lock phase P. In addition, in a state in which the relative rotational phase is further shifted to the largest advance angle side from the intermediate lock phase P, the torsion spring  218  is configured to have no spring force (bias force). 
     As a specific configuration, the torsion spring  218  has a base end  218   a  (one end) which is supported by a latching portion  214 A of the front plate  214  (on the outer rotor  211  side) and a functioning end  218   b  (the other end) which is disposed at a position to be inserted in an opening  212 S of the inner rotor  212  and in a recessed engagement portion  211 S of the outer rotor  211 . 
     A width of the recessed engagement portion  211 S is formed to correspond to a region in which the functioning end  218   b  of the torsion spring  218  is shifted, within the region of the relative rotational phase from the largest retardation angle phase to the intermediate lock phase P. The recessed engagement portion  211 S has a regulation wall  211 St with which the functioning end  218   b  comes into contact when the relative rotational phase is disposed at the intermediate lock phase P. 
     The opening  212 S is formed to correspond to the region in which the functioning end  218   b  of the torsion spring  218  is shifted, in the region of the relative rotational phase from the intermediate lock phase P to the largest advance angle. The opening  212 S has a pressure receiving wall  212 St with which the functioning end  218   b  comes into contact and which applies the bias force in a region of the relative rotational phase from the largest retardation angle phase to the intermediate lock phase P. 
     In this configuration, as shown in  FIG. 13 , in a case where the relative rotational phase becomes the largest retardation angle phase, the functioning end  218   b  of the torsion spring  218  does not come into contact with the regulation wall  211 St of the recessed engagement portion  211 S, but comes into contact with the pressure receiving wall  212 St of the opening  212 S. In this manner, the bias force of the torsion spring  218  acts on in a direction in which the relative rotational phase is shifted in the advance angle direction S 1 . 
     In addition, as shown in  FIG. 14 , in a case where the relative rotational phase becomes intermediate lock phase P, the functioning end  218   b  of the torsion spring  218  comes into contact with the regulation wall  211 St of the recessed engagement portion  211 S and into contact with the pressure receiving wall  212 St of the opening  212 S. In this manner, the bias force of the torsion spring  218  does not act on the inner rotor  212 . Particularly, at the intermediate lock phase P, the bias force of the torsion spring  218  is balanced with the retardation angle actuating force and thereby, the relative rotational phase is maintained at the intermediate lock phase P. 
     Further, as shown in  FIG. 15 , in a case where the relative rotational phase is further disposed in the advance angle direction S 1  from the intermediate lock phase P and in a state in which the functioning end  218   b  of the torsion spring  218  comes into contact with the regulation wall  211 St of the recessed engagement portion  211 S, the pressure receiving wall  212 St of the opening  212 S becomes separated from the functioning end  218   b  and the bias force of the torsion spring  218  does not act on the inner rotor  212 . 
     Modification Example of Torsion Spring 
     As shown in the graph in  FIG. 24 , the spring force is set to a value greater than the retardation angle actuating force (average value of the reactive forces) in a region of the relative rotational phase between the largest retardation angle phase to the intermediate lock phase P. In addition, in a case where the relative rotational phase is disposed at the intermediate lock phase P, the spring force is equal to the retardation angle actuating force. In a state in which the relative rotational phase is further shifted to the largest advance angle side from the intermediate lock phase P, the torsion spring  218  may be configured to cause the spring force (bias force) to be less than the retardation angle actuating force. 
     In the modification example, the spring force is linearly changed with respect to the relative rotational phase. In this respect, the opening  212 S or the recessed engagement portion  211 S may not be formed and thus, the configuration is simplified. 
     Valve Timing Control Unit: Flow Path Configuration 
     An advance angle flow path  221  that communicates with the advance angle chamber Ra, a retardation angle flow path  222  that communicates with the retardation angle chamber Rb, and an unlock flow path  223  that unlocks the lock (restriction) of the lock mechanism L are formed in the inner rotor  212 . 
     As shown in  FIG. 11 , a hydraulic joint section  224  is provided on the outer periphery of the intake camshaft  206  and a port that communicates with the advance angle flow path  221 , the retardation angle flow path  222 , and the unlock flow path  223  is formed in the hydraulic joint section  224 . 
     The control valve V realizes control of supplying and discharging the hydraulic oil (an example of a fluid) from the hydraulic pump Q, to and from the advance angle flow path  221 , the retardation angle flow path  222 , and the unlock flow path  223 . 
     Control Valve 
     As shown in  FIG. 16  to  FIG. 20 , the control valve V is configured to include a cylindrical sleeve  231 , a columnar spool  232  that is accommodated in the sleeve, a spool spring  233  that biases the spool  232  to an initial position (lock start position PA 1  shown in  FIG. 21 ), and an electromagnetic solenoid  234  that causes the spool  232  to operate against the bias force of the spool spring  233 . 
     The sleeve  231  and the spool  232  are coaxially disposed and an axial core thereof is referred to as a spool axial core Y. In addition, the electromagnetic solenoid  234  is configured to have a solenoid coil  234 B that is disposed on an outer periphery of a plunger  234 A configured of a magnetic material such as iron. The electromagnetic solenoid  234  has a function that the more the power supply to the solenoid coil  234 B is increased, the more the spool  232  is shifted against the bias force of the spool spring  233 . 
     In a state in which no power is supplied to the electromagnetic solenoid  234 , the spool  232  is positioned at the lock start position PA 1  (initial position). The spool  232  is configured to be disposed through operation at an advance angle position PA 2 , a neutral position PL, a retardation angle position PB 2 , in this order, in response to an increase of the power supplied to the electromagnetic solenoid  234 . In addition,  FIG. 21  shows a relationship between the supply and discharge of the hydraulic oil at the positions. 
     In the sleeve  231 , an advance angle port  231 A that communicates with the advance angle flow path  221 , a retardation angle port  231 B that communicates with the retardation angle flow path  222 , an unlock port  231 L that causes unlocking pressure to act on the lock member  225  by communicating with the unlock flow path  223  are formed. In addition, in the sleeve  231 , a first pump port  231 Pa to which the hydraulic oil is supplied from the hydraulic pump Q, a second pump port  231 Pb, and three drain ports  231 D are formed. 
     Particularly, the advance angle port  231 A and the retardation angle port  231 B are disposed to have a positional relationship of being adjacent in a direction parallel to the spool axial core Y and the first pump port  231 Pa and the second pump port  231 Pb are disposed on a back surface side (opposite side interposing the spool axial core Y therebetween) thereof. 
     In the spool  232 , a first land portion  232 La for controlling the hydraulic oil, a second land portion  232 Lb, a third land portion  232 Lc, a fourth land portion  232 Ld, and a fifth land portion  232 Le are formed. In addition, a first groove  232 Ga is formed on the electromagnetic solenoid  234  side from the first land portion  232 La and a second groove  232 Gb is formed between the first land portion  232 La and the second land portion  232 Lb. A third groove  232 Gc, a fourth groove  232 Gd, and a fifth groove  232 Ge are formed at positions in accordance with the above description. 
     Lock Start Position 
     As shown in  FIG. 16 , in a case where the spool  232  is set at the lock start position PA 1 , the hydraulic oil from the first pump port  231 Pa is supplied to the advance angle port  231 A and the retardation angle port  231 B and the hydraulic oil from the unlock port  231 L is discharged to the drain port  231 D. 
     Specifically, the hydraulic oil from the first pump port  231 Pa is supplied to the advance angle port  231 A through the second groove  232 Gb. At the same time, a part of the hydraulic oil in the second groove  232 Gb is supplied to the retardation angle port  231 B through a divergence portion F between an outer periphery of the second land portion  232 Lb and an inner periphery of the sleeve  231 . In addition, the hydraulic oil from the unlock port  231 L is discharged to the drain port  231 D on the tip side through the fifth groove  232 Ge. 
     The divergence portion F is configured to include a divergence groove  232 F formed over the entire outer periphery of the second land portion  232 Lb and a recessed divergence portion  231 F formed over the entire inner periphery of the sleeve  231 , which corresponds to the second land portion  232 Lb. In this configuration, in a case where the spool  232  is set at the lock start position PA 1 , a part of the hydraulic oil in the second groove  232 Gb is supplied to the retardation angle port  231 B through the divergence portion F (recessed divergence portion  231 F and divergence groove  232 F). 
     That is, the hydraulic oil is supplied to the advance angle chamber Ra and the retardation angle chamber Rb and the hydraulic oil is discharged from the unlock port  231 L such that the lock mechanism can enter into the locked state. Thus, at the lock start position PA 1 , the relative rotational phase is not shifted due to the pressure of the hydraulic oil. For example, in a case where the relative rotational phase is disposed on the retardation angle side from the intermediate lock phase P, the relative rotational phase is shifted in the advance angle direction S 1  due to the bias force of the torsion spring  218  and the lock mechanism L can enter into the locked state at the time when the relative rotational phase reaches the intermediate lock phase P shown in  FIG. 12 . 
     Conversely, in a case where the relative rotational phase is disposed on the advance angle side from the intermediate lock phase P, the relative rotational phase is shifted in the retardation angle direction S 2  due to the retardation angle actuating force from the intake camshaft  206  which is applied in the retardation angle direction S 2  and the lock mechanism L can enter into the locked state at the time when the relative rotational phase reaches the intermediate lock phase P shown in  FIG. 12 . 
     In a case where the spool  232  starts to move from the lock start position PA 1  to the advance angle position PA 2 , the control valve V is configured to maintain a state of supplying the hydraulic oil to the advance angle chamber Ra and the retardation angle chamber Rb at a transition position PA 1   a  shown in  FIG. 17  in a process of a movement, to supply the hydraulic oil to the recessed intermediate lock portion  227 , and to easily unlock the lock mechanism L. The spool  232  is not held at the transition position PA 1   a  in the control. In this disclosure, the control valve V may be configured to have only the lock start position PA 1  on the functioning end of the spool  232  and the transition position PA 1   a  may be formed. 
     As will be described below, at the advance angle position PA 2 , the hydraulic oil is supplied to the advance angle port  231 A, the hydraulic oil from the retardation angle port  231 B is discharged, and the hydraulic oil is supplied to the unlock port  231 L. That is, at the advance angle position PA 2 , an operation of causing the relative rotational phase to be shifted in the advance angle direction S 1  and control of unlocking the lock mechanism L are performed at the same time. In such an operational aspect, a shear force is applied to the lock member  225  in a shear direction from the outer rotor  211  and the inner rotor  212  and it is difficult to unlock the lock member  225  in some cases. 
     In order to solve the difficulty of unlocking, at the transition position PA 1   a , while a state of supplying the hydraulic oil from the first pump port  231 Pa to the advance angle port  231 A and the retardation angle port  231 B as shown in  FIG. 17  is maintained, the hydraulic oil from the second pump port  231 Pb is supplied to the unlock port  231 L through the fourth groove  232 Gd. In this manner, the lock member  225  is separated from the recessed intermediate lock portion  227  without the shear force applied thereto such that the unlocking is easily performed. 
     Advance Angle Position 
     As shown in  FIG. 18 , in a case where the spool  232  is set at the advance angle position PA 2 , the hydraulic oil from the first pump port  231 Pa is supplied to the advance angle port  231 A through the second groove  232 Gb and the hydraulic oil from the retardation angle port  231 B is discharged to the drain port  231 D through the third groove  232 Gc. In addition, the hydraulic oil from the second pump port  231 Pb is supplied to the unlock port  231 L through the fourth groove  232 Gd. 
     In this manner, the hydraulic oil from the advance angle port  231 A is supplied to the advance angle chamber Ra and the hydraulic oil in the retardation angle chamber Rb is discharged from the retardation angle port  231 B. At the same time, the hydraulic oil is supplied to the unlock port  231 L and the lock mechanism L is unlocked. Thus, at the advance angle position PA 2 , the relative rotational phase is shifted in the advance angle direction S 1 . 
     Neutral Position 
     As shown in  FIG. 19 , in a case where the spool  232  is set at the neutral position PL, the advance angle port  231 A is closed (is blocked) in the first land portion  232 La and the retardation angle port  231 B is closed (is blocked) in the second land portion  232 Lb. Therefore, the hydraulic oil is supplied to neither the advance angle port  231 A nor the retardation angle port  231 B. In addition, the hydraulic oil from the second pump port  231 Pb is supplied to the unlock port  231 L through the fourth groove  232 Gd. 
     In this manner, while the lock mechanism L is maintained in the unlocked state, the relative rotational phase in which the hydraulic oil is neither supplied to nor discharged from the advance angle chamber Ra and the retardation angle chamber Rb is maintained. 
     Retardation Angle Position 
     As shown in  FIG. 20 , in a case where the spool  232  is set at the retardation angle position PB 2 , the hydraulic oil from the advance angle port  231 A is discharged to the drain port through the first groove  232 La and the hydraulic oil from the first pump port  231 Pa is supplied to the retardation angle port  231 B through the second groove  232 Gb. In addition, the hydraulic oil from the second pump port  231 Pb is supplied to the unlock port  231 L through the fourth groove  232 Gd. 
     In this manner, the hydraulic oil from the advance angle chamber Ra is discharged from the advance angle port  231 A and the hydraulic oil from the retardation angle port  231 B is supplied to the retardation angle chamber Rb. In addition, the hydraulic oil is supplied to the unlock port  231 L and the lock mechanism L is unlocked. Thus, at the retardation angle position PB 2 , the relative rotational phase is shifted in the retardation angle direction S 2 . 
     Modification Example of Control Valve 
     Without modifying the configuration of the embodiment described above, a configuration in which the advance angle port  231 A is interchanged with the retardation angle port  231 B may be employed. That is, the advance angle port  231 A of the embodiment is altered to the retardation angle port and the retardation angle port  231 B of the embodiment is altered to the advance angle port. That is, the operation direction of the spool  232  and the phase shift direction of the relative rotational phase are reversed, compared to a configuration in  FIG. 18 . 
     As a modification example, as shown in  FIG. 22 , a relationship between the supply and discharge of the hydraulic oil at the plurality of positions of the spool  232  of the control valve V is set. According to the modification example, the position of the spool  232  is set at the advance angle position PA 2  in a state in which no power is supplied to the electromagnetic solenoid  234  and the spool  232  is set to be disposed at the neutral position PL, the retardation angle position PB 2 , and the lock start position PB 1 , in this order, in response to an increase of the power supplied to the electromagnetic solenoid  234 . 
     According to the configuration of the modification example, the maximum power is supplied to the electromagnetic solenoid  234  and thereby the spool  232  is set at the lock start position PB 1  and the lock mechanism L can easily enter into the locked state. Further, in a case where the spool  232  is switched from the lock start position PB 1  to the retardation angle position PB 2 , similar to the process of switching from the lock start position PA 1  to the advance angle position PA 2  of the embodiment, a transition position PB 1   a  appears. At the transition position PB 1   a , the hydraulic oil is supplied to the recessed intermediate lock portion  227  using the state in which the hydraulic oil is supplied to the advance angle chamber Ra and the retardation angle chamber Rb such that it is easy to unlock the locked state of the lock mechanism L. 
     Engine Control Unit 
     As shown in  FIG. 11 , a signal is input to the engine control unit (ECU)  240  from a shaft sensor RS, an ignition switch  243 , an accelerator pedal sensor  244 , a brake pedal sensor  245 , and a phase detecting sensor  246 . The engine control unit  240  outputs a signal to control the starter motor M, the fuel control unit  207 , and the ignition control unit  208  and outputs a signal to control the control valve V. 
     The ignition switch  243  is configured as a switch which starts and stops the internal combustion engine control system, the engine control section  241  causes the engine E to start through an ON operation, and the engine control section  241  causes the engine E to stop through an OFF operation. 
     The accelerator pedal sensor  244  detects a pedaling amount of an accelerator pedal (not shown) and the brake pedal sensor  245  detects pedaling on a brake pedal (not shown). 
     During the operation of the engine E, the phase control section  242  controls of setting an optimum relative rotational phase by acquiring a signal from the shaft sensor RS, the accelerator pedal sensor  244 , the brake pedal sensor  245 , or the like and setting of an opening/closing timing of the intake valve  202  such that the phase detecting sensor  246  detects the optimum relative rotational phase. 
     Control Mode 
       FIG. 25  shows a chart of an operation mode of each component when an operation of stopping the engine E is performed in a circumstance in which the relative rotational phase is disposed on the retardation angle side from the intermediate lock phase P. That is, the engine control section  241  performs control of stopping the engine E at a timing of the OFF operation of the ignition switch  243  (IG/SW in  FIG. 25 ) and the phase control section  242  stops (cuts OFF) power supply to the electromagnetic solenoid  234 . In this manner, the number of rotation (rotational speed) of the engine E is decreased and the relative rotational phase starts to be shifted toward the intermediate lock phase P due to the spring force (bias force) of the torsion spring  218 . 
     In this manner, a state (OFF state) in which no power is supplied to the electromagnetic solenoid  234  is achieved and thereby, the control valve V is set at the lock start position PA 1  due to the bias force of the spool spring  233 . Since the crankshaft  201  of the engine E rotates even at this point, the hydraulic oil in the hydraulic pump Q is supplied to the advance angle chamber Ra and the retardation angle chamber Rb. In addition, since the hydraulic oil in the recessed intermediate lock portion  227  is discharged, the lock mechanism L enters into a state in which the locking can be performed. 
     As described above, in a case where the relative rotational phase is disposed on the retardation angle side from the intermediate lock phase P in the valve timing control unit  210 , the spring force (bias force) of the torsion spring  218  is applied in the advance angle direction S 1  as shown in  FIG. 13 , and no spring force (bias force) of the torsion spring  218  is applied in the advance angle direction S 1  in a state in which the relative rotational phase reaches the intermediate lock phase P. 
     In addition, the retardation angle actuating force from the intake camshaft  206 , which causes the relative rotational phase to be shifted in the retardation angle direction S 2  is continuously applied to the valve timing control unit  210 . However, the spring force (bias force) of the torsion spring  218  prevents the shift of the intermediate lock phase P in the retardation angle direction S 2 . In this reason, as shown in  FIG. 14 , the relative rotational phase is stably maintained in the intermediate lock phase P and it is possible for the lock mechanism L to reliably enter into the locked state. 
     Conversely, in a case where the operation of stopping the engine E is performed in a circumstance (circumstance shown in  FIG. 15 ) in which the relative rotational phase is disposed on the advance angle side from the intermediate lock phase P, the relative rotational phase is shifted in the retardation angle direction S 2  due to the retardation angle actuating force applied from the intake camshaft  206  as shown in a virtual line in  FIG. 25 . Even in this reason, the relative rotational phase is shifted to the intermediate lock phase P shown in  FIG. 14  and is stably maintained in the intermediate lock phase P. Therefore, it is possible for the lock mechanism L to reliably enter into the locked state. 
     Thus, even in a case where the relative rotational phase of the valve timing control unit  210  is disposed on any side of the retardation angle side and the advance angle side at a timing of the OFF operation of the ignition switch  243 , the relative rotational phase is shifted to the intermediate lock phase P due to the spring force of the torsion spring  218  and the retardation angle actuating force applied from the intake camshaft  206  and the locked state can be performed in the intermediate lock phase P. Particularly, since the hydraulic oil is supplied to the advance angle chamber Ra and the retardation angle chamber Rb in a case where the relative rotational phase reaches the intermediate lock phase P, the locked state is performed in a stable state without shifting the relative rotational phase in a circumstance in which the cam swinging torque is applied and vibration thereof is caused for a short time. 
     Modification Example of Control Mode 
       FIG. 26  shows an operational mode of each component when the engine E is stopped after confirming that the relative rotational phase reaches the intermediate lock phase P in a case where an operation of stopping the engine E is performed, instead of control in  FIG. 25  described above. 
     In the control mode, the signal (power) to the electromagnetic solenoid  234  of the control valve V enters into an OFF state at a timing of the OFF operation of the ignition switch  243 ; however, the operation of the engine E is continued. 
     In this manner, the control valve V is set at the lock start position PA 1  due to the bias force of the spool spring  233 . At this point, since the engine E operates, a sufficient amount of the hydraulic oil from the hydraulic pump Q is supplied to the advance angle chamber Ra and the retardation angle chamber Rb, and the hydraulic oil in the recessed intermediate lock portion  227  is discharged such that the lock mechanism L enters into a state in which the locking can be performed. 
     In a case where the relative rotational phase is disposed on the retardation angle side from the intermediate lock phase P as shown in  FIG. 13 , the spring force (bias force) of the torsion spring  218  is applied in the advance angle direction S 1  and the relative rotational phase reaches the intermediate lock phase P as shown in  FIG. 14 . In addition, in a case where the relative rotational phase is disposed on the advance angle side from the intermediate lock phase P as shown in  FIG. 15 , the retardation angle actuating force from the intake camshaft  206  is applied in the retardation angle direction S 2  as shown in a virtual line in  FIG. 26  and the relative rotational phase reaches the intermediate lock phase P as shown in  FIG. 14 . 
     In this manner, the lock mechanism L easily enters into the locked state and the engine control section  241  stops the engine E and ends the control. 
     According to the modification example, since the engine E operates until the relative rotational phase reaches the intermediate lock phase P, the sufficient amount of the hydraulic oil is supplied to the advance angle chamber Ra and the retardation angle chamber Rb for a short time and thereby it is possible to enter into the locked state in a state in which the shift of the relative rotational phase is smoothly controlled. 
     Operation Mode Performed when Engine is Started 
     It is possible to conceive a case in which it is not possible for the lock mechanism L to enter into the locked state even when the control described above is performed, when the engine E is stopped. Since the intermediate lock phase P means a phase in which the engine E having a cold state is caused to smoothly operate, it is desirable that the relative rotational phase reaches the intermediate lock phase P in response to the start of the engine E in a case where the lock mechanism L of the valve timing control unit  210  does not enter into the locked state. The valve timing control apparatus A of this disclosure is configured to meet such demand described above. 
     That is,  FIG. 27  shows a chart of a control mode of each component at the time of starting the engine E. The starter motor M is operated and the engine E starts at a timing of the ON operation of the ignition switch  243 . In addition, at the time of the starting, a state (OFF state) is maintained, in which no power is supplied to the electromagnetic solenoid  234  of the control valve V. 
     In this manner, the hydraulic oil of the hydraulic pump Q is supplied to the advance angle chamber Ra and the retardation angle chamber Rb and the hydraulic oil in the recessed intermediate lock portion  227  is discharged such that the lock mechanism L enters into the lockable state. 
     During the control, in a case where the relative rotational phase is disposed on the retardation angle side from the intermediate lock phase P as shown in  FIG. 13 , the spring force (bias force) of the torsion spring  218  is applied in the advance angle direction S 1  and the relative rotational phase reaches the intermediate lock phase P as shown in  FIG. 14 . In addition, in a case where the relative rotational phase is disposed on the advance angle side from the intermediate lock phase P as shown in  FIG. 15 , the retardation angle actuating force from the intake camshaft  206  is applied in the retardation angle direction S 2  as shown in a virtual line in  FIG. 26  and the relative rotational phase reaches the intermediate lock phase P as shown in  FIG. 14 . 
     In this manner, the relative rotational phase is rapidly shifted to the intermediate lock phase P and it is possible to enter into the locked state. 
     Switching from Lock Start Position to Advance Angle Position 
     When the operation mode of the control valve V after the starting of the engine E is taken into account, the first switching of the spool  232  is performed from the lock start position PA 1  to the advance angle position PA 2 . 
     The control valve V according to this disclosure has a configuration in which the hydraulic oil is supplied to the recessed intermediate lock portion  227  such that the lock member  225  is caused to move and the unlocking is performed, in the process of moving from the lock start position, PA 1  to the advance angle position PA 2 , as described above, using a mode in which the hydraulic oil is supplied to the advance angle chamber Ra and the retardation angle chamber Rb at the transition position PA 1   a.    
       FIG. 28  shows a chart of the operation. That is, no power is supplied to the electromagnetic solenoid  234  at the time of starting the engine E and the spool  232  of the control valve V is disposed at the lock start position PA 1 . The hydraulic oil is supplied to the advance angle port  231 A and the retardation angle port  231 B from the hydraulic pump Q in response to the starting of the engine E and an advance angle port pressure and a retardation angle port pressure are increased to a pump pressure. 
     A control signal to switch the spool  232  to the advance angle position PA 2  is output at a timing when a set time T elapses after the start of the engine E and the spool  232  reaches the transition position PA 1   a  shown in  FIG. 17  after the spool  232  starts the operation. While a state of supplying the hydraulic oil from the first pump port  231 Pa to the advance angle port  231 A and the retardation angle port  231 B is maintained at the position, the hydraulic oil from the second pump port  231 Pb is supplied to the unlock port  231 L through the fourth groove  232 Gd. 
     In this manner, it is possible to separate the lock member  225  of the lock mechanism L from the recessed intermediate lock portion  227  and to perform the unlocking before the spool  232  reaches the advance angle position PA 2 . Then, the spool  232  reaches the advance angle position PA 2  and thereby, it is possible to shift the relative rotational phase in the advance angle direction S 1 . 
     Effects of Third Embodiment 
     The valve timing control apparatus A according to this disclosure includes the torsion spring  218  that causes the spring force (bias force) to be applied in the region from the largest retardation angle phase to the intermediate lock phase P and the bias force in the biasing direction of the torsion is set to be higher than the retardation angle actuating force applied from the intake camshaft  206 . 
     Therefore, in any cases where the engine E stops and the engine E starts, the spool  232  of the control valve V is set at the lock start position PA 1  and thereby, the hydraulic oil is supplied to the advance angle chamber Ra and the retardation angle chamber Rb in a state in which the hydraulic oil is discharged from the unlock port  231 L. Therefore, the hydraulic pressure is balanced and the shift of the relative rotational phase due to the cam swinging torque becomes small. In the state, a configuration is not employed, in which the relative rotational phase is shifted due to the pressure of the hydraulic oil but, the relative rotational phase is shifted to the intermediate lock phase P due to the spring force or the retardation angle actuating force and the lock mechanism L reliably enters into the locked state. Particularly, since the hydraulic oil is supplied to the advance angle chamber Ra and the retardation angle chamber Rb at the same time without leakage at the lock start position PA 1 , the advance angle chamber Ra and the retardation angle chamber Rb are rapidly filled with the hydraulic oil and it is possible to prevent the shift of the relative rotational phase. 
     In addition, in a case where the lock start position PA 1  of the control valve V is set to a state in which power supply to the electromagnetic solenoid  234  is stopped, it is possible to prevent the relative rotational phase from fluttering and to stably perform the locked state in a state in which the relative rotational phase reaches the intermediate lock phase P, without any special control, during the control of stopping the engine E and during the control of starting the engine E. 
     For example, even in a case where it is not possible for the lock mechanism L to enter into the locked state when the engine E is stopped, the spool  232  of the control valve V is maintained at the lock start position PA 1  when the engine E is started and thereby, it is easy to enter into the locked state after the engine E is started. 
     Further, in a case where the spool  232  of the control valve V is switched from the lock start position PA 1  to the advance angle position PA 2  after the engine E is started, it is possible to supply the hydraulic oil to the advance angle chamber Ra and the retardation angle chamber Rb in the process in which the spool  232  reaches the advance angle position PA 2  and to separate the lock member  225  of the lock mechanism L from the recessed intermediate lock portion  227  in a state in which the relative rotational phase is not shifted and the smooth unlocking is realized. 
     Fourth Embodiment 
     A fourth embodiment has a configuration in which the control valve V (control valve) of the third embodiment is modified. According to the fourth embodiment, since the valve timing control unit  210  described in the third embodiment is controlled, the same reference signs are attached to the same components as the third embodiment. 
     As shown in  FIG. 29  to  FIG. 34 , similar to the third embodiment, the control valve V of the fourth embodiment is also configured to include the cylindrical sleeve  231 , a columnar spool  232  that is accommodated in the sleeve, the spool spring  233  that biases the spool  232  to an initial position (first retardation angle position PB 1  shown in  FIG. 29 ), and the electromagnetic solenoid  234  that causes the spool  232  to operate against the bias force of the spool spring  233 . 
     The electromagnetic solenoid  234  is configured to have the solenoid coil  234 B that is disposed on an outer periphery of the plunger  234 A configured of a magnetic material such as iron. The electromagnetic solenoid  234  has a function that the more the power supply to the solenoid coil  234 B is increased, the more the spool  232  is shifted against the bias force of the spool spring  233 . 
     In a state in which no power is supplied to the electromagnetic solenoid  234 , the spool  232  is positioned at the first retardation angle position PB 1  (initial position: the first position). The spool  232  is configured to be disposed through operation at the second retardation angle position PB 2 , the neutral position PL, the second advance angle position PA 2 , the first advance angle position PA 1 , and an oil filling position PA 0  as the second position, in this order, in response to an increase of the power supplied to the electromagnetic solenoid  234 . In addition,  FIG. 35  shows a relationship between the supply and discharge of the hydraulic oil at the positions. 
     In the sleeve  231 , the advance angle port  231 A that communicates with the advance angle flow path  221 , the retardation angle port  231 B that communicates with the retardation angle flow path  222 , the unlock port  231 L that causes the unlocking pressure to act on the lock member  225  by communicating with the unlock flow path  223  are formed. In addition, in the sleeve  231 , the first pump port  231 Pa to which the hydraulic oil is supplied from the hydraulic pump Q, the second pump port  231 Pb, and the three drain ports  231 D are formed. 
     In the spool  232 , the first land portion  232 La for controlling the hydraulic oil, the second land portion  232 Lb, the third land portion  232 Lc, the fourth land portion  232 Ld, and the fifth land portion  232 Le are formed. In addition, the first groove  232 La is formed on the electromagnetic solenoid  234  side from the first land portion  232 La and the second groove  232 Gb is formed between the first land portion  232 La and the second land portion  232 Lb. The third groove  232 Gc, the fourth groove  232 Gd, and the fifth groove  232 Ge are formed at positions in accordance with the above description. The plurality of land portions and the plurality of grooves have the same functions as in the third embodiment during the operation of the spool  232 . 
     In addition, a first divergence portion F 1  is formed between the outer periphery of the first land portion  232 La and the inner periphery of the sleeve  231  and a second divergence portion F 2  is formed between the outer periphery of the fourth land portion  232 Ld and the inner periphery of the sleeve  231 . 
     The control valve V is configured such that the spool  232  further moves after the spool  232  moves from the second advance angle position PA 2  to the first advance angle position PA 1  and thereby, the spool  232  reaches the oil filling position PA 0 . 
     Operational Mode 
     Thus, as shown in  FIG. 29 , in a case where the spool  232  is set at the first retardation angle position PB 1 , the hydraulic oil is discharged from the advance angle chamber Ra and, at the same time, the hydraulic oil is supplied to the retardation angle chamber Rb. In addition, the hydraulic oil is discharged from the recessed intermediate lock portion  227  and thereby, the relative rotational phase is shifted in the retardation angle direction S 2  and the lock mechanism L (an example of the intermediate lock mechanism) enters into the locked state in a case where the relative rotational phase reaches the intermediate lock phase. 
     Next, as shown in  FIG. 30 , in a case where the spool  232  moves from the first retardation angle position PB 1  to the second retardation angle position PB 2 , while a state of discharging the hydraulic oil from the advance angle chamber Ra and supplying the hydraulic oil to the retardation angle chamber Rb is maintained, the hydraulic oil is supplied to the recessed intermediate lock portion  227  and thereby, the lock mechanism L starts to be unlocked. In this manner, the relative rotational phase is shifted in the retardation angle direction. 
     Next, as shown in  FIG. 31 , in a case where the spool  232  is operated to be disposed at the neutral position PL, the advance angle port  231 A is closed (is blocked) in the second land portion  232 Lb and the retardation angle port  231 B is closed (is blocked) in the first land portion  232 La. Therefore, the hydraulic oil is supplied to neither the advance angle chamber Ra nor the retardation angle chamber Rb. Since the hydraulic oil from the second pump port  231 Pb is supplied to the unlock port  231 L through the fourth groove  232 Gd at the neutral position PL, the locked state of the lock mechanism L is unlocked. 
     In addition, as shown in  FIG. 32 , in a case where the spool  232  is set at the second advance angle position PA 2 , the hydraulic oil is supplied to the advance angle chamber Ra and, at the same time, the hydraulic oil is discharged from the retardation angle chamber Rb. Since the hydraulic oil is supplied to the recessed intermediate lock portion  227  at the second advance angle position PA 2 , the locked state of the lock mechanism L is unlocked and the relative rotational phase is shifted in the advance angle direction S 1 . 
     Next, as shown in  FIG. 33 , in a case where the spool  232  is operated to move from the second advance angle position PA 2  to the first advance angle position PA 1 , while a state of supplying the hydraulic oil to the advance angle chamber Ra and discharging the hydraulic oil from the retardation angle chamber Rb is maintained, the hydraulic oil is discharged from the recessed intermediate lock portion  227 . In this manner, the lock mechanism L enters into the locked state in a case where the relative rotational phase reaches the lock phase. 
     In addition, as shown in  FIG. 34 , the spool  232  is further operated after the spool  232  reaches the first advance angle position PA 1  and thereby the spool  232  reaches the oil filling position PA 0 . At the oil filling position PA 0 , the hydraulic oil is supplied to the advance angle chamber Ra and the retardation angle chamber Rb at the same time, and the hydraulic oil is discharged from the recessed intermediate lock portion  227 . 
     As specific flowing of the hydraulic oil, in a case where the spool  232  moves to the oil filling position PA 0 , the hydraulic oil from the first pump port  231 Pa is supplied from the retardation angle port  231 B to the retardation angle chamber Rb through supplied the first divergence portion F 1  and supplies the hydraulic oil from the first pump port  231 Pa to the advance angle chamber Ra from the second groove  232 Gb and from the advance angle port  231 A. In addition, the second divergence portion F 2  discharges the hydraulic oil flowing from the recessed intermediate lock portion  227  to the unlock port  231 L to the drain port  231 D. 
     For example, when switching from a state in which the second retardation angle position PB 2  is unlocked to the locked state, the supply of the hydraulic oil to the recessed intermediate lock portion  227  is stopped and the hydraulic oil is supplied only to the advance angle chamber Ra and is discharged from the retardation angle chamber Rb, before the spool  232  reaches the first advance angle position PA 1 . In the configuration, it is possible to shift the relative rotational phase due to differential pressure produced between the advance angle chamber Ra and the retardation angle chamber Rb and it is possible for the lock mechanism L to reliably enter into the locked state. 
     Effects of Fourth Embodiment 
     The spool  232  of the control valve V is set at the oil filling position PA 0  in the case of starting the engine E and thereby, the hydraulic oil is supplied to the advance angle chamber Ra and the retardation angle chamber Rb at the same time in a state in which the hydraulic oil is discharged from the recessed intermediate lock portion  227 . Therefore, it is possible to rapidly fill the advance angle chamber Ra and the retardation angle chamber Rb with the hydraulic oil and it is possible to rapidly start the operation of the valve timing control apparatus. 
     Other Embodiments 
     This disclosure may have the following configurations, other than the embodiments described above. 
     (a) As shown in  FIG. 36 , the supply and discharge of the hydraulic oil are set at the plurality of positions of the spool  232  of the control valve V. In the other embodiment (a), the spool  232  is disposed at the lock start position PA 1  in a state in which no power is supplied to the electromagnetic solenoid  234 . The spool  232  is set at the advance angle position PA 2 , the neutral position PL, the retardation angle position PB 2 , and a retardation angle side lock position PB 0 , in this order, in response to an increase of the power supplied to the electromagnetic solenoid  234 . 
     According to the other embodiment (a), the lock start position PA 1 , the advance angle position PA 2 , the neutral position PL, and the retardation angle position PB 2  are common with the embodiment and the retardation angle side lock position PB 0  means a position at which the relative rotational phase is shifted in the retardation angle direction S 2  and it is possible for the lock mechanism L to enter into the locked state. 
     The other embodiment (a) also has a configuration in which a state of supplying the hydraulic oil to the advance angle chamber Ra and the retardation angle chamber Rb by forming the transition position in the process from the lock start position PA 1  to the advance angle position PA 2  of the control valve V of the embodiment is maintained and the hydraulic oil is supplied to the recessed intermediate lock portion  227 . 
     The other embodiment (a) may also employ a configuration in which switching between the advance angle port  231 A and the retardation angle port  231 B is performed without changing the configuration of the control valve V. In addition, in the configuration, only the lock start position PA 1  may be formed on the functioning end of the spool  232  and the transition position may not be formed. 
     (b) As shown in  FIG. 37 , the supply and discharge of the hydraulic oil at the plurality of positions of the spool  232  of the control valve V are set. In the other embodiment (b), partially similar to the positions of the other embodiment (a) described above, the spool  232  is disposed at the lock start position PA 1  in a state in which no power is supplied to the electromagnetic solenoid  234 . The maximum power is supplied to the electromagnetic solenoid  234  and thereby, the spool  232  is set at the lock start position PB 1 . In this configuration, the lock mechanism L easily enters into the locked state at both the lock start positions PA 1  and PB 1 . 
     The other embodiment (b) also has a configuration in which a state of supplying the hydraulic oil to the advance angle chamber Ra and the retardation angle chamber Rb by forming the transition position in the process from the lock start position PB 1  to the retardation angle position PB 2  of the control valve V of the embodiment is maintained and the hydraulic oil is supplied to the recessed intermediate lock portion  227 . 
     The other embodiment (b) may also employ a configuration in which switching between the advance angle port  231 A and the retardation angle port  231 B is performed without changing the configuration of the control valve V. In addition, in the configuration, only the lock start position PB 1  may be formed on the functioning end of the spool  232  and the transition position may not be formed. 
     (c) As the phase setting mechanism, a ratchet mechanism may be configured to shift the relative rotational phase in a direction against the reactive force from the camshaft in a region in which the lock phase is reached from the largest retardation angle phase or the largest advance angle phase. 
     (d) As the phase setting mechanism, an assist-only oil chamber may be separately formed to shift the relative rotational phase in a direction against the reactive force from the camshaft and may be configured to supply the hydraulic oil to the oil chamber and thereby, to cause the relative rotational phase to move to the intermediate lock phase P. In the case of such a configuration, an accumulator that enables the hydraulic oil to be supplied to the oil chamber during the stop of the engine E may be provided. 
     (e) In a case where a spring is used as the phase setting mechanism, the spring is not limited to the torsion spring, but a compression coil spring or a tension coil spring may be used and rubber or a gas spring may be used instead of the spring. 
     (f) As the phase setting mechanism, a control mode of the engine control unit  240  may be set to perform control of supplying the hydraulic oil to the advance angle flow path  221  and the retardation angle flow path  222  based on the relative rotational phase immediately before the spool  232  is set at the lock start position. 
     The control mode is set as in the other embodiment (f) and thereby, the relative rotational phase can be shifted toward the intermediate lock phase P and it is possible to easily enter into the locked state. 
     (g) As the phase setting mechanism, a flow path structure may be provided, in which a flow rate difference is generated between the hydraulic oil which is supplied to the advance angle flow path  221  and the hydraulic oil which is supplied to the retardation angle flow path  222  in a case where the spool  232  is set at the lock start position. The flow path structure may be realized through setting a sectional area of the flow path but the control valve V may be provided such that the hydraulic oil is controlled when the spool  232  is disposed at the lock start position. 
     According to the configuration as in the other embodiment (g), it is possible to shift the relative rotational phase toward the lock phase. 
     (h) As the phase setting mechanism, a configuration may be provided, in which the hydraulic oil from one of the advance angle flow path  221  and the retardation angle flow path  222  slightly leaks to the drain flow path at the lock start position. A configuration may be employed, in which the hydraulic oil in one flow path is discharged to the drain flow path through an orifice or the control valve V may have the configuration such that the hydraulic oil is discharged to the drain flow path in the spool  232  at the lock start position. 
     According to the configuration as in the other embodiment (h), it is possible to easily shift the relative rotational phase toward the lock phase. 
     (i) According to the embodiment in  FIG. 4 , the hydraulic oil in the first recessed portion  85  and the second recessed portion  86  is discharged through the unlock flow path  45 ; however, the configuration is not limited thereto. For example, the hydraulic oil in the first recessed portion  85  and the second recessed portion  86  may be discharged through the locking discharge flow path  46  in a state in which the unlock flow path  45  is closed. Alternatively, the hydraulic oil in the first recessed portion  85  and the second recessed portion  86  may be discharged through both the unlock flow path  45  and the locking discharge flow path  46 . 
     An aspect of this disclosure is directed to a valve timing control apparatus including: a drive-side rotational member that synchronously rotates with a drive shaft of an internal combustion engine; a driven-side rotational member that is disposed inside the drive-side rotational member to be coaxial to the drive-side rotational member and that integrally rotates with a valve opening/closing camshaft of the internal combustion engine; a hydrostatic pressure chamber that is formed by partitioning a space between the drive-side rotational member and the driven-side rotational member; an advance angle chamber and a retardation angle chamber that are formed by dividing the hydrostatic pressure chamber with a dividing section provided on at least one of the drive-side rotational member and the driven-side rotational member; an intermediate lock mechanism that is able to selectively switch, through supplying and discharging of a hydraulic fluid, between a locked state in which a relative rotational phase of the driven-side rotational member to the drive-side rotational member is restricted to an intermediate lock phase between the largest advance angle phase and the largest retardation angle phase and an unlocked state in which the restriction to the intermediate lock phase is released; an advance angle flow path that allows the hydraulic fluid which is supplied to and discharged from the advance angle chamber to be circulated; a retardation angle flow path that allows the hydraulic fluid which is supplied to and discharged from the retardation angle chamber to be circulated; a control valve that has a spool which moves between a first position in a case where a power supply amount is zero and a second position different from the first position in a case of power supply; and a phase control unit that controls the control valve by controlling a power supply amount to the control valve and that supplies a hydraulic fluid to the advance angle chamber and the retardation angle chamber to shift the relative rotational phase. When the spool is disposed at one of the first position and the second position, the hydraulic fluid is set to be supplied to both the advance angle chamber and the retardation angle chamber. 
     In this configuration, when the internal combustion engine is started, it is possible to supply the hydraulic fluid to both the advance angle chamber and the retardation angle chamber and to fill the chambers in an early stage such that the operation of the valve timing control apparatus is rapidly started. 
     In the aspect of this disclosure, a hydraulic fluid may be supplied to one of the advance angle flow path or the retardation angle flow path before the spool reaches the second position from the first position. 
     In this configuration, it is easy to shift the relative rotational phase at any direction between the advance angle direction and the retardation angle direction. 
     In the aspect of this disclosure, when the spool is disposed at one of the first position and the second position, the intermediate lock mechanism may enter into a locked state and the hydraulic fluid may be supplied to one of the advance angle chamber and the retardation angle chamber and may be discharged from the other chamber, and when the spool is disposed at the other position of the first position and the second position, the intermediate lock mechanism may enter into a locked state and the hydraulic fluid may be supplied to both the advance angle chamber and the retardation angle chamber. 
     In this configuration, in a case where the spool is disposed at one of the first position and the second position, the intermediate lock mechanism enters into the locked state and the hydraulic fluid is supplied to one of the advance angle chamber and the retardation angle chamber. In addition, in a case where the spool is disposed at the other position of the first position and the second position, the intermediate lock mechanism enters into the locked state and the hydraulic fluid is supplied to both the advance angle chamber and the retardation angle chamber. 
     In the aspect of this disclosure, when the spool is disposed at one of the first position and the second position, the advance angle chamber and the retardation angle chamber may communicate with each other through a communication path formed in the spool such that a part of the hydraulic fluid is supplied to one of the advance angle chamber and the retardation angle chamber and a part of the hydraulic fluid is supplied to the other chamber through the communication path. 
     The spool is disposed at the first position or the second position and thereby, for example, a part of the hydraulic fluid is supplied to the advance angle chamber and a part of the hydraulic fluid is supplied to the retardation angle chamber through the communication path. In this manner, when the internal combustion engine is started, it is possible to fill the advance angle chamber and the retardation angle chamber with the hydraulic fluid at an early stage and it is possible to rapidly start the operation of the valve timing control apparatus immediately after the internal combustion engine is started. 
     In the aspect of this disclosure, the valve timing control apparatus may further include a phase setting mechanism that shifts the relative rotational phase to the intermediate lock phase. When the spool is disposed at one of the first position and the second position, the phase setting mechanism may have a flow path allowing a part of a hydraulic fluid to flow out from one of the advance angle flow path and the retardation angle flow path. 
     For example, the intermediate lock mechanism does not enter into the locked state when the internal combustion engine is stopped and the relative rotational phase is maintained at the retardation angle. Even in such a state, at the next starting, the spool is disposed at the first position or the second position and thereby, the hydraulic fluid flows out from the retardation angle flow path such that it is easy to shift the relative rotational phase to the advance angle direction and to cause the intermediate lock mechanism to enter into the locked state. 
     In the aspect of this disclosure, the valve timing control apparatus may further include a phase setting mechanism that shifts the relative rotational phase to the intermediate lock phase. When the spool is disposed at one of the first position and the second position, the phase setting mechanism may have a flow path structure in which a flowing amount of a hydraulic fluid which is supplied to the advance angle flow path is caused to be different from a flowing amount of a hydraulic fluid which is supplied to the retardation angle flow path. 
     For example, the intermediate lock mechanism does not enter into the locked state when the internal combustion engine is stopped and the relative rotational phase is maintained at the retardation angle. Even in such a state, at the next starting, the spool is disposed at the first position or the second position and thereby, the relative rotational phase is shifted to the advance angle direction due to the difference in the flow rates of the hydraulic fluid such that the intermediate lock mechanism easily enters into the locked state. 
     In the aspect of this disclosure, the valve timing control apparatus may further include a phase setting mechanism that shifts the relative rotational phase to the intermediate lock phase. The phase setting mechanism may be provided with a spring that has a bias force which exceeds, in size, average torque calculated by fluctuating torque of the camshaft and that causes the bias force to act on shifting the relative rotational phase from the largest retardation angle phase to the intermediate lock phase. 
     In this configuration, when the internal combustion engine is stopped and started, the hydraulic fluid is not sufficiently supplied to the advance angle chamber and the retardation angle chamber. Even in a case where the intermediate lock mechanism does not enter into the locked state, the relative rotational phase is likely to be shifted to the lock phase by a reactive force from the camshaft and a bias force of the spring. Thus, since the relative rotational phase is set substantially to the intermediate phase when the internal combustion engine is stopped, the next start of the internal combustion engine is stable. 
     This disclosure can be applied to a valve timing control apparatus that controls a relative rotational phase of a driven-side rotational member to a drive-side rotational member which is synchronized with and rotates with a crankshaft of an internal combustion engine. 
     The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.