Patent ID: 8789503
Filing Date: 2014-07-29
Classification: F01L

Abstract:
1. A valve timing control apparatus comprising: an inner peripheral member rotatable in unison with a valve opening/closing cam shaft rotatably assembled to a cylinder head of an internal combustion engine; a vane rotatable in unison with said inner peripheral member; an outer peripheral member rotatable relative to said inner peripheral member; a plurality of fluid pressure chambers disposed between said inner peripheral member and said outer peripheral member and divided by said vane into an advanced angle chamber and a retarded angle chamber; a first fluid passageway for feeding/discharging fluid to/from said advanced angle chamber; a second fluid passageway for feeding/discharging fluid to/from said retarded angle chamber; a phase holding mechanism for holding a relative phase between said inner peripheral member and said outer peripheral member to a predetermined phase between a most advanced angle phase and a most retarded angle phase, said phase holding mechanism including a restricting member, an accommodating hole for slidably accommodating said restricting member, and a receiving hole for receiving said restricting member, said phase holding mechanism being configured to hold said relative phase as said restricting member is received and engaged into said receiving hole; a pump feeding fluid to said advanced angle chamber or said retarded angle chamber through said first fluid passageway or said second fluid passageway; and a fluid control valve for switching over the passage for the fluid discharged from said pump to either said first fluid passageway or said second fluid passageway and controlling the feeding amount of said fluid; wherein said restricting member having a large diameter portion, an intermediate diameter portion having a smaller diameter than said large diameter portion and formed on the receiving hole side portion of said large diameter portion, and a small diameter portion having a smaller diameter than said intermediate diameter portion and formed on the receiving hole side portion of said intermediate diameter portion, said small diameter portion being engageable within said receiving hole, a first pressure receiving face being a stepped face between said large diameter portion and said intermediate diameter portion and a second pressure receiving face being a stepped face between said intermediate diameter portion and said small diameter portion; said phase holding mechanism further includes a first inlet communicated to one of said advanced angle chamber and said retarded angle chamber, said first inlet being configured so that the fluid from the one of said advanced angle chamber and said retarded angle chamber enters through said first inlet and applies fluid pressure of one of said advanced angle chamber and said retarded angle chamber to said first pressure receiving face and a second inlet communicated to the other of said advanced angle chamber and said retarded angle chamber, said second inlet being configured so that the fluid from the other of said advanced angle chamber and said retarded angle chamber enters through said second inlet and applies fluid pressure of the other of said advanced angle chamber and said retarded angle chamber to said second pressure receiving face; when said relative phase is held to said predetermined phase, said first inlet is blocked by said large diameter portion; the holding state of said relative phase is released as the fluid pressure of the other of said advanced angle chamber and said retarded angle chamber to whichever said fluid control valve starts feeding of the fluid entering through said second inlet applies fluid pressure to said second pressure receiving face; and after releasing of said holding state of said relative phase holding mechanism, the releasing state of said relative phase holding mechanism is maintained by at least one of the application to said first pressure receiving face of the fluid pressure of said advanced angle chamber and the application to said second pressure receiving face of the fluid pressure of said retarded angle chamber.