Patent Publication Number: US-8522734-B2

Title: Valve timing control device

Description:
This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application 2009-125754, filed on May 25, 2009, the entire content of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     This disclosure relates to a valve timing control device including a driving side rotational member synchronously rotatable with a crankshaft of an internal combustion engine, a driven side rotational member arranged coaxially with the driving side rotational member and synchronously rotatable with a camshaft that controls the opening and closing operation of valves of the internal combustion engine, a fluid pressure chamber formed by the driving side rotational member and the driven side rotational member, a partition portion installed on at least one of the driving side rotational member and the driven side rotational member to partition the fluid pressure chamber into an advanced angle chamber and a retarded angle chamber, a lock member mounted in an accommodation portion formed in either the driving side rotational member or the driven side rotational member and protruding and withdrawing with respect to the rotational member opposite to the accommodation portion, a lock groove formed in the opposite rotational member so that the lock member protrudes and is locked to the lock groove, the lock groove confining a relative rotational phase of the driven side rotational member with respect to the driving side rotational member at a most advanced angle phase, a most retarded angle, or a predetermined phase between the most advanced angle phase and the most retarded angle phase when the lock member is locked, and a lock release passage supplying an operating fluid to the lock member to withdraw the lock member from the lock groove. 
     BACKGROUND DISCUSSION 
     In a valve timing control device, when an operating fluid of a lock release passage is acted on a lock member to withdraw the lock member from a lock groove, if foreign substances, such as minute metal pieces or metal powder, are mixed with the operating fluid, the foreign substances tend to stay in the lock groove. If the foreign substances are jammed between the lock member and the lock groove, it is a hindrance in the smooth displacement of the lock member, which is liable to result in a bad influence on the extending or withdrawing operation of the lock member. 
     For this reason, a valve timing control device of a related art has a foreign substance receiving space in the rotational member formed with an accommodation portion for the lock member, in which the foreign substance receiving space is communicated with the lock groove when the relative rotational phase of a driven side rotational member with respect to the driving side rotational member is adjusted at a specific phase. Since the foreign substances are collected in the foreign substance receiving space, the jamming of the foreign substances is prevented (e.g., refer to JP-A-2007-247509 (Patent Document 1)). 
     In the related art, the jamming of the foreign substances is prevented by collecting the foreign substances in the foreign substance receiving space. Therefore, as the foreign substances are stacked in the foreign substance receiving space, the stacked foreign substances are liable to flow out toward the lock groove in accordance with rotation stop of the internal combustion engine. As a result, there is a drawback in that it is difficult to prevent the foreign substances from jamming between the lock member and the lock groove for a long period of time. 
     A need thus exists for a valve timing control device which is not susceptible to the drawback mentioned above. 
     SUMMARY 
     According to a first aspect of this disclosure, a valve timing control device includes a driving side rotational member synchronously rotatable with a crankshaft of an internal combustion engine; a driven side rotational member arranged coaxially with the driving side rotational member and synchronously rotatable with the camshaft that controls the opening and closing operation of valves of the internal combustion engine; a fluid pressure chamber formed by the driving side rotational member and the driven side rotational member; a partition portion installed on at least one of the driving side rotational member and the driven side rotational member to partition the fluid pressure chamber into an advanced angle chamber and a retarded angle chamber; a lock member mounted in an accommodation portion formed in either the driving side rotational member or the driven side rotational member and protruding and withdrawing with respect to the rotational member opposite to the accommodation portion; a lock groove formed in the opposite rotational member so that the lock member protrudes and is locked to the lock groove, the lock groove confining a relative rotational phase of the driven side rotational member with respect to the driving side rotational member at a most advanced angle phase, a most retarded angle, or a predetermined phase between the most advanced angle phase and the most retarded angle when the lock member is locked; and a lock release passage supplying an operating fluid to the lock member to withdraw the lock member from the lock groove, wherein the lock release passage is in communication with the lock groove, and the rotational member formed with the accommodation portion is provided with an atmosphere open passage which is in communication with the lock groove when the relative rotational phase is at a specific phase. 
    
    
     
       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 cross-sectional view illustrating an overall structure of a valve timing control device; 
         FIG. 2  is a perspective view illustrating the operating configuration of a fluid control valve; 
         FIG. 3  is a cross-sectional view taken along the line in  FIG. 1  in a specific operation state; 
         FIG. 4  is a cross-sectional view taken along the line in  FIG. 1  in a specific operation state; 
         FIG. 5A  is a cross-sectional view taken along the line in  FIG. 1  in a specific operation state, and  FIG. 5B  is a cross-sectional view of a major portion; 
         FIG. 6A  is a cross-sectional view taken along the line in  FIG. 1  in a specific operation state, and  FIG. 6B  is a cross-sectional view of a major portion; 
         FIG. 7  is a cross-sectional view taken along the line III-III in  FIG. 1  in a specific operation state; 
         FIG. 8  is a cross-sectional view illustrating a specific operation state of a second embodiment; 
         FIG. 9  is a cross-sectional view illustrating a specific operation state of a second embodiment; and 
         FIG. 10  is a cross-sectional view illustrating a specific operation state of a second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments disclosed here will now be described with reference to the accompanying drawings. 
     First Embodiment 
       FIG. 1  is a side cross-sectional view illustrating an overall structure of a valve timing control device according to an embodiment disclosed here.  FIG. 2  is a view illustrating the operating configuration of a fluid control valve (OCV) V 1  installed in the valve timing control device.  FIGS. 3 ,  4 ,  5 A,  6 A and  7  are cross-sectional views taken along the line III-III in  FIG. 1  in each operation state of the valve timing control device.  FIGS. 5B and 6B  are cross-sectional views of a major portion. 
     A valve timing control device includes an outer rotor  1  serving as a driving side rotational member and synchronously rotatable with a crankshaft (not shown) of an engine (an internal combustion engine) in a direction denoted by an arrow S in the figure, and an inner rotor  2  serving as a driven side rotational member and synchronously rotatable with a camshaft  3  which opens and closes a valve of the engine, in a direction denoted by the arrow S in the figure, in which the inner rotor  2  is supported on an inner periphery of the outer rotor  1  and rotates relatively with respect to the outer rotor  1 . 
     The outer rotor  1  and the inner rotor  2  are coaxially arranged in such a manner that they are relatively slidable and rotatable around a core X of a rotational shaft. A fluid pressure chamber  4  is formed between the outer rotor  1  and the inner rotor  2 . The fluid pressure chamber  4  is partitioned into a retarded angle chamber  4   a  and an advanced angle chamber  4   b  by a vane  5  serving as a partition portion installed therein. 
     If operating oil is supplied to the retarded angle chamber  4   a  or the advanced angle chamber  4   b , the outer rotor  1  and the inner rotor  2  rotate relatively. If the volume of the retarded angle chamber  4   a  is increased, the relative rotational phase of the inner rotor  2  with respect to the outer rotor  1  is displaced towards a retarded angle side (in a direction of the arrow S 1  in the figure). If the volume of the advanced angle chamber  4   b  is increased, the same relative rotational phase of the inner rotor  2  with respect to the outer rotor  1  is displaced towards an advanced angle side (in a direction of the arrow S 2  in the figure). 
     The outer rotor  1  includes a cylindrical rotor body  1   a  externally carried to be relatively slidable and rotatable within a predetermined phase range extending between a most advanced angle phase and a most retarded angle phase with respect to the inner rotor  2 , and a front plate  1   b  and a rear plate  1   c  which are connected to the rotor body  1   a  at front and rear sides thereof by a screw or the like. A timing sprocket  6  is integrally installed on the rotor body  1   a.    
     Between the timing sprocket  6  and the gear mounted on the crankshaft of the engine, there is provided a power transmission member  7  such as a timing belt. 
     If the crankshaft of the engine rotates, a rotational force is transmitted to the timing sprocket  6  through the power transmission member  7 , and the outer rotor  1  rotates in a rotational direction shown by the arrow S in the figure. 
     Upon rotation of the outer rotor  1 , the inner rotor  2  rotates in the same rotational direction as the outer rotor  1  to rotate the camshaft  3 , and a cam provided on the camshaft  3  pushes an intake valve or an exhaust valve down to open the valve. 
     The valve timing control device includes a lock mechanism  8  that controls the relative rotational phase of the inner rotor  2  with respect to the outer rotor  1  at an intermediate lock phase which is suitable for the start of an internal combustion engine between the most advanced angle phase and the most retarded angle phase, as shown in  FIG. 3 . 
     The engine is provided with a sensor detecting a current crank angle and a sensor detecting an angle phase of the camshaft  3 . 
     An electronic control unit (ECU)  9  controlling the valve timing control device disclosed here includes a phase judgment mechanism which detects the relative rotational phase of the inner rotor  2  with respect to the outer rotor  1  from the detect result of these sensors to judge whether the relative rotational phase is the advanced angle phase or the retarded angle phase with respect to the intermediate lock phase. 
     The electronic control unit  9  is adapted to store and save the optimum relative rotational phase in accordance with a driving state of the engine in a memory, and to recognize the optimum relative rotational phase with respect to the driving state (engine revolutions, temperature of cooling water or the like) separately detected. 
     Accordingly, the electronic control unit  9  generates and outputs a control command controlling the relative rotational phase so as to make the relative rotational phase suitable for the driving state of the engine. Further, the electronic control unit  9  is adapted to receive ON/OFF information from an ignition key, and information from an oil temperature sensor detecting the temperature of engine oil, or the like. 
     In this embodiment, as the revolutions of the engine increase, the relative rotational phase is adjusted to be near the most advanced angle phase. In this instance, in a case in which the relative rotational phase is adjusted to be near the most advanced angle phase, large output torque, such as start at the incline, is required, as well as a case in which the revolutions of the engine are high. Even though the revolutions of the engine are low, the relative rotational phase is near the most advanced angle phase. 
     The configuration of the valve timing control device disclosed here will now be described in detail. 
     (Fluid Pressure Chamber) 
     As shown in  FIG. 3  to  FIG. 7 , a plurality of protrusions  10  each serving as a shoe protruding in a radially inner direction are arranged on the rotor body  1   a  of the outer rotor  1  at intervals from each other along the rotational direction. A fluid pressure chamber  4  is formed between adjacent protrusions  10  of the outer rotor  1 . 
     A vane groove  11  is formed on an external periphery portion of the inner rotor  2  facing each fluid pressure chamber  10 . A vane  5  partitioning the inside of the fluid pressure chamber  4  into an advanced angle chamber  4   a  and a retarded angle chamber  4   b  which are adjacent to each other in a relative rotational direction (i.e. in the direction of arrows S 1  and S 2  in the figure) is slidably supported in the vane groove  11  along a radial direction of the rotational member. 
     The advanced angle chamber  4   b  is in communication with an advanced angle passage  12  formed on the inner rotor  2 , and the retarded angle chamber  4   a  is in communication with a retarded angle passage  13  formed on the inner rotor  2 . The advanced angle passage  12  and the retarded angle passage  13  are connected to an oil pressure circuit  15  which is connected to an oil pan  14  of the engine. 
     (Oil Pressure Circuit) 
     The oil pressure circuit  15  performs supply and discharge of the engine oil to and from either or both of the advanced angle chamber  4   b  and the retarded angle chamber  4   a  through the advanced angle passage  12  and the retarded angle passage  13  as the operating oil to change the position of the vane  5  in the fluid pressure chamber  4 . Consequently, the oil pressure circuit serves as a phase control mechanism capable of adjusting the relative rotational phase of the inner rotor  2  with respect to the outer rotor  1  within a phase range extending over the most advanced angle phase (the relative rotational phase when the volume of the advanced angle chamber  4   b  is maximized) and the most retarded angle phase (the relative rotational phase when the volume of the retarded angle chamber  4   a  is maximized). 
     More specifically, the oil pressure circuit  15  includes, as shown in  FIG. 1  and  FIG. 3 , a pump P driven by the driving force of the engine to supply the engine oil serving as the operating oil (one example of the operating fluid) to a fluid control valve (OCV) V 1  and a fluid switching valve (OSV) V 2 . Revolutions of the pump are controlled in accordance with a control command from the electronic control unit  9 . 
     The advanced angle passage  12  and the retarded angle passage  13  are connected to desired ports of the fluid control valve V 1 , and a retarded angle restriction-lock release passage  16  and an advanced angle restriction-lock release passage  17  which will be described below are connected to desired ports of the fluid switching valve V 2 . 
     The supply and discharge of the operating oil to and from the fluid pressure chamber  4  (the retarded angle chamber  4   a  and the advanced angle chamber  4   b ) is performed by the pump P arranged in the oil pressure circuit  15  and the fluid control valve V 1  of a spool type. 
     As shown in  FIG. 2  and  FIG. 3 , the fluid control valve V 1  can adjust the supply amount and the discharge amount of the operating oil to and from the advanced angle chamber  4   b  and the retarded angle chamber  4   a  by performing a switching control of a spool position among a first state W 1  in which the operating oil is supplied to the advanced chamber  4   b  and is discharged from the retarded angle chamber  4   a , a second state W 2  in which the operating oil is supplied to advanced angle chamber  4   b  and the retarded angle passage  13  is closed, a third state W 3  in which both of the advanced angle passage  12  and the retarded angle passage  13  are closed and the supply of the operating oil to both of the advanced angle chamber  4   b  and the retarded angle chamber  4   a  is stopped, a fourth state W 4  in which the advanced angle passage  12  is closed and the operating oil is supplied to the retarded angle chamber  4   a , and a fifth state W 5  in which the operating oil is discharged from the advanced angle chamber  4   b  and the operating oil is supplied to the retarded angle chamber  4   a.    
     More specifically, since the electronic control unit  9  controls the amount of electricity supplied to a linear solenoid (not shown) installed in the fluid control valve V 1 , the position of the spool slidably supported in the housing of the fluid control valve V 1  is adjusted in left and right positions in  FIG. 3 . However, in  FIG. 2 , as the position of the spool is shifted from Duty 0% to Duty 50%, the degree of opening in the advanced angle passage  12  is gradually decreased. Similarly, as the position of the spool is shifted from Duty 100% to Duty 75%, the degree of opening in the retarded angle passage  13  is gradually decreased. 
     The fluid switching valve V 2  performs the lock and the lock release at the intermediate lock phase by supplying and discharging the operating oil to and from the lock mechanism  8 . 
     That is, the locking and releasing operation of a retarded angle restriction-lock piece (one example of the lock member)  18  to and from the retarded angle restriction-lock groove  20  and the locking and releasing operation of an advanced angle restriction-lock piece (one example of the lock member)  19  to and from the advanced angle restriction-lock groove  21  are performed by the fluid switching valve V 2  which is operated independently from the oil pressure control by the fluid control valve V 1 . For this reason, in a state in which the oil pressure is not stable immediately after the engine stops, each of the lock pieces  18  and  19  can be easily locked to the lock grooves  20  and  21  reliably. 
     In this embodiment, the lock grooves  20  and  21  and the lock release passages  16  and  17  are not in communication with the retarded angle chamber  4   a , the advanced angle chamber  4   b , the advanced angle passage  12  and the retarded angle passage  13 . For this reason, for example, even though the operating oil is discharged from the advanced angle chamber  4   b  or the retarded angle chamber  4   a  when the fluid control valve V 1  is in the first state W 1  or the fifth state W 5 , the operating oil is not discharged from the lock grooves  20  and  21  and the lock release passages  16  and  17 . 
     (Biasing Mechanism) 
     As shown in  FIG. 1 , a torsion spring  22  serving as a biasing mechanism for biasing the relative rotational phase of both rotors  1  and  2  towards the advanced angle side is installed between the inner rotor  2  and the outer rotor  1 . 
     The torsion spring  22  biases the inner rotor  2  to the outer rotor  1  in the direction (advanced angle side) denoted by the arrow S 2 . Consequently, this serves to solve the problem of the relative phase of the inner rotor  2  rotating integrally with the camshaft  3  being frequently delayed to the rotation of the outer rotor  1  since the camshaft  3  receives the resistance from the valve spring. 
     (Lock Mechanism) 
     As shown in  FIG. 3  to  FIG. 7 , the lock mechanism  8  includes the retarded angle restriction-lock portion  23  and the advanced angle restriction-lock portion  24  provided in the outer rotor  1 , and a lock concave portion  25  formed in the outer circumference of the inner rotor  2  in a groove shape along an arc around the core X of the rotational shaft thereof. 
     The retarded angle restriction-lock portion  23  has a retarded angle restriction-lock piece  18 , and the advanced angle restriction-lock portion  24  has an advanced angle restriction-lock piece  19 . 
     The retarded angle restriction-lock piece  18  is mounted so as to be protruded or withdrawn to or from a retarded angle-accommodating portion  26  formed in the outer rotor  1  with respect to the inner rotor  2 , and the advanced angle restriction-lock piece  19  is mounted so as to be protruded or withdrawn to or from an advanced angle-accommodating portion  27  formed in the outer rotor  1  with respect to the inner rotor  2 . 
     The lock concave portion  25  is formed in a groove shape extending over the entire width along the core X of the relative rotational shaft of the inner rotor  2 , and is installed in such a manner that each of the retarded angle restriction-lock piece  18  and the advanced angle-restriction-lock piece  19  protrudes and abuts against a bottom surface of the lock concave portion. 
     At the inside of the lock concave portion  25  two lock grooves of the retarded angle restriction-lock groove  20  and the advanced angle restriction-lock groove  21  are dividedly arranged and opened at both ends in the circumferential direction thereof. 
     Consequently, the retarded angle restriction-lock groove  20  and the advanced angle restriction-lock groove  21  are in communication with each other through the lock concave portion  25 . 
     The front end portion of the retarded angle restriction-lock piece  18  protruding toward the inner rotor  2  can be locked to the retarded angle restriction-lock groove  20 . The front end portion of the advanced angle restriction-lock piece  19  protruding toward the inner rotor  2  can be locked to the advanced angle restriction-lock groove  21 . 
     The length of the lock concave portion  25  in the circumferential direction of the rotational member is set in such a manner that the retarded angle restriction-lock piece  18  and the advanced angle restriction lock-piece  19  are simultaneously locked to the lock grooves  20  and  21 , respectively. 
     As shown in  FIG. 3 , when the retarded angle restriction-lock piece  18  is locked to the retarded angle restriction-lock groove  20  and the advanced angle restriction-lock piece  19  is locked to the advanced angle restriction-lock groove  21 , the relative rotational phase of the inner rotor  2  with respect to the outer rotor  1  is restricted at the intermediate lock phase. 
     Each of the retarded angle restriction-lock piece  18  and the advanced angle restriction-lock piece  19  is provided with a spring  28  biasing the lock pieces to protrude the lock pieces toward the inner rotor  2 . The spring  28  is installed in such a manner that the lock pieces can be switched to a lock posture in which the lock pieces are locked to the lock grooves  20  and  21  by the biasing force of the spring  28 , and a lock release posture in which the lock pieces are withdrawn from the lock grooves  20  and  21  against the biasing force of the spring  28 . 
     A rod-type lock pin may be employed as the lock pieces  18  and  19 , in addition to the lock piece of a plate shape shown in this embodiment. 
     The retarded angle-lock release passage  16  is in communication with the bottom surface of the retarded angle restriction-lock groove  20 , and the advanced angle-lock release passage  17  is in communication with the bottom surface of the advanced angle restriction-lock groove  21 . 
     Since the operating oil of the retarded angle-lock release passage  16  acts on the retarded angle restriction-lock piece  18  of the lock posture, the retarded angle restriction-lock piece  18  can be withdrawn from the retarded angle restriction-lock groove  20 , and be switched to the lock release posture. 
     Since the operating oil of the advanced angle-lock release passage  17  acts on the advanced angle restriction-lock piece  19  of the lock posture, the advanced angle restriction-lock piece  19  can be withdrawn from the advanced angle restriction-lock groove  21 , and be switched to the lock release posture. 
     Since the retarded angle restriction-lock piece  18  protrudes from the lock concave portion  25 , the rotational range of the inner rotor  2  from the intermediate lock phase to the retarded angle side (direction denoted by the arrow S 1 ) with respect to the outer rotor  1  is restricted. 
     Since the advanced angle restriction-lock piece  19  protrudes from the lock concave portion  25 , the rotational range of the inner rotor  2  from the intermediate lock phase to the advanced angle side (direction denoted by the arrow S 2 ) with respect to the outer rotor  1  is restricted. 
     In the intermediate lock phase, if the retarded angle-lock release passage  16  or the advanced angle-lock release passage  17  is in communication with the oil pan  14  by operation of the fluid switching valve V 2 , the oil pressure is lowered, as shown in  FIG. 3 , and the retarded angle restriction-lock piece  18  or the advanced angle restriction-lock piece  19  is switched to the lock posture by the biasing force of the spring  28 . 
     Further, if the retarded angle-lock release passage or the advanced angle-lock release passage  17  is in communication with the pump P by operation of the fluid switching valve V 2 , the oil pressure is raised, as shown in  FIG. 4 , and the retarded angle restriction-lock piece  18  or the advanced angle restriction-lock piece  19  is switched to the lock release posture, in which the lock piece is withdrawn toward the outer rotor  1 , against the biasing force of the spring  28 . 
     The outer rotor  1  is provided with a common atmosphere open passage  29  along a radial direction of the rotational member, which is in communication with the retarded angle restriction-lock groove  20  and the advanced angle restriction-lock groove  21  when the relative rotational phase of the inner rotor  2  with respect to the outer rotor  1  is at a specific phase. 
     The atmosphere open passage  29  is formed in the rotor body  1   a , and is in communication with the retarded angle restriction-lock groove  20  and the advanced angle restriction-lock groove  21  at the most advanced angle phase to be adjusted when the revolutions of the engine is high at a specific phase, as shown in  FIG. 5A . The advanced angle restriction-lock groove  21  is in communication with the atmosphere open passage  29  through the lock concave portion  25 . 
     If the atmosphere open passage  29  is in communication with each of the lock grooves  20  and  21  in a state in which each of the lock release passages  16  and  17  is connected to the pump P, the operating oil of the retarded angle-lock release passage  16  is discharged outwardly from the outer rotor  1  via the retarded angle restriction-lock groove  20  and the atmosphere open passage  29 , and the operating oil of the advanced angle-lock release passage  17  is discharged outwardly from outer rotor  1  via the advanced angle restriction-lock groove  21 , the lock concave portion  25  and the atmosphere open passage  29 . 
     Consequently, even though the foreign substances mixed with the operating oil stay in the retarded angle restriction-lock groove  20  or the advanced angle restriction-lock groove  21 , the foreign substances can be discharged outwardly from the outer rotor  1  via the atmosphere open passage  29  together with the operating oil. 
     If the atmosphere open passage  29  is in communication with the lock grooves  20  and  21 , the pressure of the operating oil in the lock concave portion  25  is lowered. For this reason, the retarded angle restriction-lock piece  18  which is withdrawn toward the outer rotor  1  side at a position near the lock concave portion  25  protrudes and displaces toward the lock concave portion  25  by the biasing force of the spring  28 , as shown in  FIG. 6B , so that the end portion abuts against the bottom surface  30  of the concave portion. Consequently, the communication between the advanced angle restriction-lock groove  21  and the atmosphere open passage  29  via the lock concave portion  25  may be interrupted. 
     Accordingly, in order to communicate the advanced angle restriction-lock groove  21  with the atmosphere open passage  29  in a case where the retarded angle restriction-lock piece  18  protrudes and abuts against the bottom portion of the lock concave portion  25  at a specific phase in which the lock grooves  20  and  21  are in communication with the atmosphere open passage  29 , the bottom portion of the lock concave portion  25  is provided with a groove  31  along the circumferential direction of the inner rotor  2 . 
     In this embodiment, as shown in  FIG. 3 , by forming the atmosphere open passage  29  to have a passage cross-section smaller than that of the respective lock release passages  16  and  17 , the outflow quantity of the operating oil from the atmosphere open passage  29  via the oil pressure circuit of the fluid switching valve V 2  side is suppressed, and sudden deterioration in the pressure of the operating oil in the oil pressure circuit of the fluid control valve V 1  side is suppressed. 
     When the atmosphere open passage  29  is in communication with the lock grooves  20  and  21 , the pressure of the operating oil in the fluid pressure chamber  4  is set to be equal to or more than the minimum operating pressure which can adjust the relative rotational phase and to be equal to or more than a pressure which can suppress a fluctuation of the relative rotational phase in the advanced angle direction and the retarded angle direction due to the torque fluctuation acting from the camshaft  3 . 
     The groove  31  is formed at both sides of the bottom surface  30  of the concave portion along the circumferential direction of the rotational member. As shown in  FIG. 6B , even though the front end surface of the retarded angle restriction-lock piece  18  abuts against the bottom surface of the concave portion  30 , it is possible to ensure the communication of the advanced angle restriction-lock groove  21  with the atmosphere open passage  29  via the groove  31 . 
     After the operating oil is discharged outwardly, as shown in  FIG. 7 , if the communication of the atmosphere open passage  29  with the lock concave portion  25  is interrupted by displacing the relative rotational phase of the outer rotor  1  and the inner rotor  2  to the retarded angle side, the pressure of the operating oil is increased. Therefore, the retarded angle restriction-lock piece  18  is withdrawn from the lock concave portion  25 , and is switched to the lock release posture, thereby adjusting the desired relative rotational phase. 
     Second Embodiment 
       FIG. 8  to  FIG. 10  show other embodiments of the valve timing control device disclosed here, in which the retarded angle restriction-lock groove  20  is formed only one end side of the lock concave portion  25 , and the advanced angle restriction-lock groove  21  is formed away from the other end of the lock concave portion  25 . 
     As shown in  FIG. 8 , the rotation range of the inner rotor  2  to the outer rotor  1  from the intermediate lock phase to the retarded angle side (direction denoted by the arrow  51 ) is restricted by protruding the retarded angle restriction-lock piece  18  into the lock concave portion  25 . 
     As shown in  FIG. 9 , the retarded angle restriction-lock piece  18  is locked to the retarded angle restriction-lock groove  20  and the advanced angle restriction-lock piece  19  is locked to the advanced angle restriction-lock groove  21 , the relative rotational phase of the inner rotor  2  to the outer rotor  1  is restricted at the intermediate lock phase. 
     As shown in  FIG. 10 , the outer rotor  1  is provided with a retarded angle atmosphere open passage  29   a  which is in communication with the retarded angle restriction-lock groove  20 , and an advanced angle atmosphere open passage  29   b  which is in communication with the advanced angle restriction-lock groove  21 , when the relative rotational phase of the inner rotor  2  to the outer rotor  1  is at a specific phase (most advanced angle phase). 
     The lock concave portion  25  may be formed on the advanced angle restriction-lock groove  21 . In this instance, the lock concave portion  25  is extended toward the advanced angle side with respect to the advanced angle restriction-lock groove  21 , that is, the retarded angle restriction-lock groove  20  side: Consequently, in a case in which the inner rotor  2  is positioned at the retarded angle side upon stop of the engine, the advanced angle restriction-lock piece  19  protrudes first toward the lock concave portion  25  to restrict the rotational phase of the inner rotor  2  and thus easily perform the engagement of the retarded angle restriction-lock piece  18 . 
     Other configurations are similar to those of the first embodiment. 
     Other Embodiments 
     1. In the valve timing control device disclosed here, the partition portion may be installed on the driving side rotational member. 
     2. In the valve timing control device disclosed here, the accommodation portion in which the lock member is mounted may be installed on the driven side rotational member. 
     3. The valve timing control device disclosed here may include a lock groove restricting the relative rotational phase of the driven side rotational member to the driving side rotational member at the most advanced angle phase or the most retarded angle phase when the lock member is locked. 
     4. The valve timing control device disclosed here may include a single lock member and a single lock groove to which the lock member is locked. 
     5. In the valve timing control device disclosed here, an interface surface between a rotor body  1   a  and a front plate  1   b  which constitute the outer rotor  1 , an interface surface between a rotor body  1   a  and a rear plate  1   c  which constitute the outer rotor  1 , or the front plate  1   b  or the rear plate  1   c  itself may be provided with the atmosphere open passage. 
     6. The valve timing control device disclosed here may be provided with an atmosphere open passage which is opened in the inside of the engine block. 
     7. In the valve timing control device disclosed here, the atmosphere open passage is in communication with the lock groove at the specific phase which is adjusted when the output torque required for the internal combustion engine during the relative rotational phase is large. 
     According to a first aspect of this disclosure, a valve timing control device includes a driving side rotational member synchronously rotatable with a crankshaft of an internal combustion engine; a driven side rotational member arranged coaxially with the driving side rotational member and synchronously rotatable with the camshaft that controls the opening and closing operation of valves of the internal combustion engine; a fluid pressure chamber formed by the driving side rotational member and the driven side rotational member; a partition portion installed on at least one of the driving side rotational member and the driven side rotational member to partition the fluid pressure chamber into an advanced angle chamber and a retarded angle chamber; a lock member mounted in an accommodation portion formed in either the driving side rotational member or the driven side rotational member and protruding and withdrawing with respect to the rotational member opposite to the accommodation portion; a lock groove formed in the opposite rotational member so that the lock member protrudes and is locked to the lock groove, the lock groove confining a relative rotational phase of the driven side rotational member with respect to the driving side rotational member at a most advanced angle phase, a most retarded angle, or a predetermined phase between the most advanced angle phase and the most retarded angle when the lock member is locked; and a lock release passage supplying an operating fluid to the lock member to withdraw the lock member from the lock groove, wherein the lock release passage is in communication with the lock groove, and the rotational member formed with the accommodation portion is provided with an atmosphere open passage which is in communication with the lock groove when the relative rotational phase is at a specific phase. 
     According to the valve timing control device of this disclosure, since the lock release passage is in communication with the lock groove, when the relative rotational phase of the driven side rotational member with respect to the driving side rotational member is at a specific phase, the lock groove is in communication with the atmosphere open passage, the operating fluid of the lock release passage passes through the lock groove and the atmosphere opening passage, and then is discharged outwardly. 
     Consequently, in a case where foreign substances remain in the lock groove, the foreign substances can be discharged outwardly together with the operating fluid, thereby preventing the foreign substances from jamming between the lock member and the lock groove for a long period of time. 
     In addition, according to the valve timing control device of this disclosure, when the internal combustion engine is actually used and immediately after the valve timing control device is attached to the internal combustion engine, if the relative rotational phase is set to a specific phase by supplying the operating fluid to the valve timing control device, it is possible to discharge the foreign substances at that time. 
     Consequently, before the internal combustion engine is actually used, for example, it is possible to discharge the foreign substances when the valve timing control device is attached to a vehicle of the internal combustion engine or is inspected. In this instance, by controlling the valve timing control device so as not to make the relative rotational phase at the specific phase at the time of actually using the internal combustion engine, so that there may be a configuration in which a circumferential groove (lock concave portion) of the driving side rotational member or the driven side rotational member which will be described below is not formed. 
     According to a second aspect of this disclosure, when the atmosphere open passage is in communication with the lock groove, the pressure of the operating fluid in the fluid pressure chamber is set to be equal to or more than the minimum operating pressure capable of adjusting the relative rotational phase. 
     With the above configuration, even though the pressure of the operating fluid in the fluid pressure chamber is decreased by communication between the atmosphere open passage and the lock groove, it is possible to suppress the adjustment of the relative rotational phase from being difficult. For this reason, it is possible to perform the adjustment of relative rotational phase quickly even though the atmosphere open passage is in communication with the lock groove. 
     According to a third aspect of this disclosure, when the atmosphere open passage is in communication with the lock groove, the pressure of the operating fluid in the fluid pressure chamber is set to be equal to or more than a pressure capable of suppressing a fluctuation of the relative rotational phase in the advanced angle direction and a retarded angle direction due to fluctuation in torque applied from the camshaft. 
     According to the configuration, even though the pressure of the operating fluid in the fluid pressure chamber is decreased by the communication of the atmosphere open passage and the lock groove, it is possible to suppress the fluctuation of the relative rotational phase due to the fluctuation in the torque. Consequently, it is possible to suppress the opening or closing time of a suction valve or a discharge valve from being unintentionally varied. In this instance, the pressure of the operating fluid in the fluid pressure chamber which can suppress the fluctuation of the relative rotational phase may be a pressure to ensure that the fluctuation of the relative rotational phase due to torque fluctuation is ±2° CA or less. 
     According to a fourth aspect of this disclosure, the atmosphere open passage is installed in such a manner that the atmosphere open passage is in communication with the lock groove at a specific phase of the relative rotational phase which is adjusted when revolutions of the internal combustion engine are high or when the output torque required for the internal combustion engine is high. 
     Generally, the supply of the operating fluid to the valve timing control device is performed by using discharge oil of a mechanical pump provided in the internal combustion engine. When the revolutions of the internal combustion engine are high or when the output torque required for the internal combustion engine is high, the discharge pressure from the pump is increased. 
     With the configuration, since the revolutions of the internal combustion engine are high and the output torque required for the internal combustion engine is high, the foreign substances can be vigorously discharged outwardly through the atmosphere open passage by using the operating fluid with the high discharge pressure from the pump. Consequently, the foreign substances staying in the lock groove can be effectively discharged outwardly together with the operating fluid. 
     According to a fifth aspect of this disclosure, the driven side rotational member rotating in an inner circumferential side of the driving side rotational member is provided with the lock groove, and the driving side rotational member is provided with the atmosphere open passage along a radial direction of the rotational member. 
     The foreign substances stayed in the lock groove are applied with a centrifugal force generated by the rotation of the rotational member. In a case where the foreign substances are large metal pieces or metal powder having specific gravity greater than that of the operating fluid, large centrifugal force is applied to the foreign substances as compared with the operating fluid. 
     With the configuration, the foreign substances with the specific gravity greater than that of the operating fluid can be smoothly discharged outwardly along the atmosphere open passage formed along the radial direction of the rotational member by using the centrifugal force applied to the foreign substances, as well as the flow force of the operating force. 
     According to a sixth aspect of this disclosure, a circumference of the opposite rotational member is provided with a lock concave portion, which opens the lock groove, in a circumferential direction. In order to communicate the lock groove and the atmosphere open passage in a case where the lock member protrudes and abuts against the bottom portion of the lock concave portion, at a specific phase in which the lock groove is in communication with the atmosphere open passage, the bottom portion of the lock concave portion is provided with a groove formed in a circumferential direction of the driving side rotational member or the driven side rotational member. 
     With the above configuration, if the lock member protrudes from the lock concave portion, the relative rotational range between the driving side rotational member and the driven side rotational member is restricted. The lock concave portion is provided with the lock groove. For this reason, the lock member protruding into the lock concave portion can be locked to the lock groove by the relative rotation between the driving side rotational member and the driven side rotational member. Therefore, it is possible to easily restrict the relative rotational phase of the driven side rotational member to the driving side rotational member at a most advanced angle phase, a most retarded angle, or a predetermined phase between the most advanced angle phase and the most retarded angle phase. 
     When the driving side rotational member and the driven side rotational member are relatively rotated to be at a specific phase, the lock member is withdrawn from the lock member by acting the operating fluid of the lock release passage on the lock member. 
     If the atmosphere open passage is in communication with the lock groove at a specific phase, the pressure of the operating fluid is lowered. For this reason, the lock member tends to protrude into the lock concave portion, thereby interrupting the communication between the lock groove and the atmosphere open passage. 
     If the communication between the lock groove and the atmosphere open passage is interrupted, there is a problem in that the foreign substances staying in the lock groove are not discharged outwardly. 
     With the above configuration, in a case where the lock member abuts against the bottom portion of the lock concave portion, the lock groove can be in communication with the atmosphere open passage. 
     Consequently, it is possible to reliably discharge outwardly the foreign substances staying in the lock groove. 
     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.