| 摘要 |
A hydraulic control system for a continuously variable transmission (CVT) includes a ratio control valve for distributing fluid to components in the CVT. The ratio control valve receives a system controlled pressure and distributes both a high pressure control fluid and a low pressure control fluid. A variable bypass valve distributes excess fluid pressure back to the inlet of a control pump. The bypass valve is responsive to the pressure differential between the high pressure control fluid and the system pressure controlled fluid to establish the operating point at which the excess fluid is bypassed. The system pressure controlled fluid is the highest pressure in the system. During operation of the CVT, the high pressure control fluid operates on one variable sheave of the CVT and the low pressure control fluid operates on another variable sheave of the CVT. The ratio control valve is responsive to a feedback control that is effective to determine the required ratio for the CVT and therefore the desired levels of the high and low pressure control fluids.
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