| 摘要 |
PURPOSE: A pressure control valve of a hydraulic pressure control system is provided to stably supply hydraulic pressure regardless of temperature, to prevent the rapid change of supply flow rate, and to avoid the excessive falling of line pressure in a low-rpm range. CONSTITUTION: A pressure control valve is constituted of a valve body and a valve spool(50) integrated with a solenoid(S). The valve body includes a first port(52) supplied with hydraulic pressure from a manual valve, a second port(54) supplying the hydraulic pressure to a shift valve or a friction element, a third port(56) to which the hydraulic pressure flows from the second port, and an exhaust port(EX) discharging the hydraulic pressure from the second port. The valve spool embedded in the valve body includes a first land(60) acting by the hydraulic pressure supplied to the third port, a second land(62) selectively varying the opened area of the first port, and a third land(66) having a protrusion(64) acting by the solenoid. Gaps are formed in between the first port and the exhaust port. Hydraulic pressure is supplied while residual pressure exists between the first land and the second land. Therefore, hydraulic pressure is stably supplied even if the viscosity of a fluid is changed due to temperature change.
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