Variable valve timing control apparatus

A variable valve timing control apparatus, comprising:

• a housing integrally rotated with one of a crank shaft of an internal combustion engine and a cam shaft thereof;
• a rotor provided in the housing and integrally rotated with the other one of the crank shaft and the cam shaft;
• a hydraulic chamber defined between the housing and the rotor;
• a vane assembled in the rotor for dividing the hydraulic chamber into an advance angle chamber and a retard angle chamber;
• a relative rotation control mechanism for restraining a relative rotation between the rotor and the housing at an intermediate phase position between the most advanced angle phase position and the most retarded angle phase position in response to a fluid supplied to the relative rotation control mechanism and a fluid drained therefrom;
• and
• a fluid pressure passage which controls the fluid supplied to the advance angle chamber, the retard angle chamber, and the relative rotation control mechanism and the fluid drained therefrom, the fluid pressure passage including a first fluid path which supplies the fluid to the relative rotation control mechanism and drains the fluid therefrom independently of a second fluid path which supplies the fluid to the advance angle chamber and the retard angle chamber and drains the fluid therefrom, the fluid pressure passage further including a hydraulic pressure control valve which includes both a third fluid path and a fourth fluid path, with the third fluid path supplying the fluid to the relative rotation control mechanism and draining the fluid therefrom independently of the fourth fluid path which supplies the fluid to the advance angle chamber and the retard angle chamber and drains the fluid therefrom.

A variable valve timing control apparatus, comprising:

• a housing integrally rotated with one of a crank shaft of an internal combustion engine and a cam shaft thereof;
• a rotor provided in the housing and integrally rotated with the other one of the crank shaft and the cam shaft;
• a hydraulic chamber defined between the housing and the rotor;
• a vane assembled in the rotor for dividing the hydraulic chamber into an advance angle chamber and a retard angle chamber;
• a relative rotation control mechanism for restraining a relative rotation between the rotor and the housing at an intermediate phase position between the most advanced angle phase position and the most retarded angle phase position in response to a fluid supplied to the relative rotation control mechanism and a fluid drained therefrom;
• and
• a fluid pressure passage for controlling the fluid supplied to the advance angle chamber, the retard angle chamber, and the relative rotation control mechanism and for controlling the fluid drained therefrom, wherein the fluid pressure passage includes a first fluid path for supplying the fluid to the relative rotation control mechanism and for draining the fluid therefrom independently of a second fluid path for supplying the fluid to the advance angle chamber and the retard angle chamber and for draining the fluid therefrom and a hydraulic pressure control valve for supplying the fluid to the advance angle chamber, the retard angle chamber, and the relative rotation control mechanism and for draining the fluid therefrom, and the hydraulic pressure control valve includes a third fluid path for supplying the fluid to the relative rotation control mechanism and for draining the fluid therefrom independently of a fourth fluid path for supplying the fluid to the advance angle chamber and the retard angle chamber and for draining the fluid therefrom, and the hydraulic pressure control valve is controlled for supplying the fluid to the relative rotation control mechanism after supplying the fluid to at least one of the advance angle chamber and the retard angle chamber when the relative rotation between the rotor and the housing is shifted from a first condition to be maintained at the intermediate phase position by the relative rotation control mechanism to a second condition to be maintained at the intermediate phase position by a fluid pressure supplied to at least one of the advance angle chamber and the retard angle chamber.