Patent ID: 8210990
Filing Date: 2012-07-03
Classification: F16H,Y10T

Abstract:
1. A hydraulic control device for a multi-speed automatic transmission, comprising: a plurality of friction engagement elements; a plurality of hydraulic servos that engages and releases the plurality of friction engagement elements; a plurality of solenoid valves for engagement control that is at least one less than the plurality of hydraulic servos; a sorting switch valve that allocates an engagement pressure from at least one of the plurality of solenoid valves for engagement control to two among the plurality of hydraulic servos, wherein the sorting switch valve takes a first position that supplies the engagement pressure to one of the two hydraulic servos in at least a reverse range, a non-drive range, and a specific gear speed of a forward range, and takes a second position supplies the engagement pressure to another of the two hydraulic servos in other than the forward range, and the hydraulic control device achieves a first state that forms gear speeds using the solenoid valves for engagement control; a second state that supplies the engagement pressure to two among the plurality of hydraulic servos through two among the plurality of solenoid valves for engagement control when an all-solenoids-off failure occurs; and a third state that cuts off a source pressure to all the solenoid valves for engagement control when the all-solenoids-off failure occurs, wherein a state variable oil passage that passes through the sorting switch valve and modifies the second state and the third state depending on a pressure output state, the second state is achieved when the all-solenoids-off failure occurs while the sorting switch valve is in a second position, and the third state is achieved when the all-solenoids-off failure occurs while the sorting switch valve is in a first position.