| 摘要 |
A hydraulic control for an automatic shifting transmission has a plurality of shift logic valves, a high ratio control valve, a low ratio control valve and respective pressure control valves for controlling the bias pressure on the ratio control valves. The shift logic valves control the distribution of fluid to a plurality of torque transmitting mechanisms from the proper ratio control valve. During an upshift sequence, the high ratio control valves establishes the engagement pressure in the oncoming torque transmitting mechanism and the low ratio control valve establishes the engagement pressure in the offgoing torque transmitting mechanism. The pressure from the high ratio control valve is also delivered to a control port on the low ratio control valve to force the exhausting of the offgoing torque transmitting mechanism when the oncoming torque transmitting mechanism reaches its critical torque capacity. Following the ratio interchange, the shift logic valves are then positioned to disconnect the ratio control valves from the torque transmitting mechanisms and connect the oncoming torque transmitting mechanism with another source of pressure. During and subsequent to the ratio interchange, the shift logic valves maintain at least one other torque transmitting mechanism engaged with pressure from the other source of pressure.
|
