Patent ID: 7216662

Claim:
A flow control apparatus comprising: a housing providing a flow control valve hole and a bypass path communicating to intermediate portion in axial direction of said flow control valve hole; a spool slidably inserted in axial direction into said flow control valve hole to open and close communicating between a fluid introducing room communicating to said flow control valve hole and said bypass path, providing a rear room of said spool and a front room of said spool where operating fluid is introduced from an oil pump, and forced toward a side of said front room of said spool to close communicating to said bypass path; an opening provided as coaxially with said flow control valve hole on a member provided bodily on said housing at a side of said front room of said spool, and communicating said front room of said spool to an outlet of said housing; a rod provided as coaxially and bodily with said spool, passing through said opening with a clearance and providing a metering orifice between said opening; a communicating path passing through said rod in axial direction and providing a communicating path between said front room of said spool and said outlet of said housing; and a relief pressure mechanism received in said spool, releasing high pressure in rear room of said spool to said bypass path and protecting said oil pump from overload; wherein said relief pressure mechanism is comprising a relief pressure valve casing and a valve body elastically forced to a seat valve face of a seat valve member provided on said relief pressure valve casing; said relief pressure mechanism is assembled in advance as a relief pressure valve sub-assembly; a front section of opposite side of said seat valve member provided on said relief pressure valve casing is press fitted to a press fitting hole opening to said rear room of said spool so that a receiving room of said valve body in said relief pressure valve casing communicates to said bypass path; and said communicating path communicates to said rear room of said spool through outside of said relief pressure valve sub-assembly.