| 摘要 |
PROBLEM TO BE SOLVED: To provide a plural function integrated spool valve wherein a plurality of valve functions, even if integrated, exert no influences on one another without using a seal member. SOLUTION: A hydraulic control system for controlling the operation of a VVT has an OCV 22 for supplying driving hydraulic pressure to an advance chamber A or a delay chamber B, and an OSV 29 for controlling the opening/closing of an advance drain control valve 25 and a delay drain control valve 28. The OCV 22 is integrated with the OSV 29. A sleeve 54 has an annular escape groove 90 in the outer peripheral face between the OCV 22 and the OSV 29 in communication with a second drain port 65. Thus, the output hydraulic pressure of each of the OCV 22 and the OSV 29 is discharged from the escape groove 90 into the second drain port 65 even when leaking into a clearance between a mounting hole of an engine head and the sleeve 54. So, with one output hydraulic pressure giving no influences to the other output hydraulic pressure, highly accurate phase control is performed. COPYRIGHT: (C)2008,JPO&INPIT
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