| 摘要 |
PURPOSE:To provide a hydraulic control device for a belt type continuous variable transmission for a vehicle, which can reduce drive belt loading even when an electromagnetic gear ratio pressure generating valve fails. CONSTITUTION:Vehicle speed pressure PV which is generated by a vehicle speed pressure generating valve 176, but is lowered as vehicle speeds V are accelerated, is applied by an oil path 219 to a second pressure regulating valve 180 as primary pressure. By this constitution, when, for example, a fifth electromagnetic valve 160 fails due to disconnection and the like, even if second line pressure PL2 regulated by the second pressure regulating valve 180 is made maximum, second line pressure PL2 can not exceed aforesaid vehicle speed pressure PV acting as prime pressure, so that aforesaid second line pressure thereby becomes equal to vehicle speed pressure. As a result, second line pressure PL2 is restricted to a low value when vehicle speeds are high where a change gear ratio gamma remains small at the acceleration side, so that pressure allowance also becomes low. On the contrary, when vehicle speeds are low where the change gear ratio gamma remains high at the deceleration side, second line pressure PL2 is also restricted to a high value, pressure allowance also becomes high, therefore drive belt loading can be kept low, so that its durability can thereby be enhanced. |
