Variable valve timing control apparatus

A variable valve timing control apparatus, comprising:

• a driving rotor rotating in synchronization with a rotation of a crankshaft for an internal combustion engine;
• a driven rotor coaxially arranged with the driving rotor and rotating in synchronization with a rotation of a camshaft of a cam opening and closing a valve for the internal combustion engine;
• a fluid pressure chamber defined between the driving rotor and the driven rotor;
• a partition portion arranged at one of the driving rotor and the driven rotor and dividing the fluid pressure chamber into an advanced angle chamber and a retarded angle chamber;
• a first fluid control mechanism controlling supply and discharge of a hydraulic fluid to and from the fluid pressure chamber to rotate the driven rotor relative to the driving rotor;
• a first phase restriction portion restricting a relative rotational phase between the driving rotor and the driven rotor within a first restriction range ranging from a predetermined phase to a phase located toward a retarded angle side from the predetermined phase, the predetermined phase being located between a most advanced angle phase and a most retarded angle phase, the first phase restriction portion releasing the relative rotational phase from the first restriction range;
• a second phase restriction portion restricting the relative rotational phase within a second restriction range ranging from the predetermined phase to a phase located toward an advanced angle side from the predetermined phase and releasing the relative rotational phase from the second restriction range;
• and
• a second fluid control mechanism controlling the supply and discharge of the hydraulic fluid to and from the first phase restriction portion and the second phase restriction portion individually,
• wherein the first phase restriction portion is arranged in a first accommodating portion formed in one of the driving rotor and the driven rotor, the first phase restriction portion including a first restriction member and a first restriction groove formed in the other of the driving rotor and the driven rotor, the first restriction member being protrudable and retractable relative to the other of the driving rotor and the driven rotor,
• wherein the second phase restriction portion is arranged in a second accommodating portion formed in one of the driving rotor and the driven rotor, the second phase restriction portion including a second restriction member and a second restriction groove formed in the other of the driving rotor and the driven rotor, the second restriction member being protrudable and retractable relative to the other of the driving rotor and the driven rotor,
• wherein a first passage supplying the hydraulic fluid to the first restriction groove is provided to retract the first restriction member from the first restriction groove and a second passage supplying the hydraulic fluid to the second restriction groove is provided to retract the second restriction member from the second restriction groove, and
• wherein the second fluid control mechanism is switchable into a first position, a second position and a third position, when the second control mechanism is in the first position, the hydraulic fluid is supplied to the first passage and the second passage, when the second fluid control mechanism is in the second position, the hydraulic fluid is supplied to one of the first passage and the second passage and is discharged from the other of the first passage and the second passage, and when the second fluid control mechanism is in the third position, the hydraulic fluid is discharged from the first passage and the second passage.