| 摘要 |
PURPOSE:To improve the durability of a drive belt, by compensating a natural pressure increase by a forcible pressure increase at a low oil temperature to thereby maintain constant a line pressure set in accordance with at a high oil temperature, in a hydraulic control device for a continuously variable transmission in a vehicle transmission. CONSTITUTION:A hydraulic system of a continuously variable transmission is provided with a pressure regulating valve 8 for a line pressure to be supplied to a speed change control valve 9. The pressure regulating valve 8 maintains a predetermined line pressure at a high oil temperature according to the operation of a spring 86 as a temperature sensing member, and forcibly reduces the line pressure at a low oil temperature. When the oil temperature in the hydraulic system is low, the spring 86 is shrunk to draw a spool 87 of an auxiliary valve 85 and thereby communicate a port 88b with a port 88a. As a result, a lubricating oil pressure is applied to a port 81e of the pressure regulating valve 8. Accordingly, a spool 82 is moved to reduce the line pressure in such a manner as to cancel a natural pressure increase associated with a decrease in oil temperature.
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