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US 2008/0176700 A1Published application
Electro-hydraulic control system with multiplexed pressure switch diagnostic system
AssigneeGM Global Technology Operations LLC
InventorsCHARLES F. LONG, BRYAN H. HAGELSKAMP
Life of this patent
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Abstract
An electro-hydraulic control system is provided, preferably for a countershaft transmission, with a diagnostic system that uses extensive multiplexing of pressure switches to provide accurate information regarding the position of valves within the control system while minimizing the number of required components.
Claims14
An electro-hydraulic control system that controls engagement of torque-transmitting mechanisms in a transmission;
- wherein the control system includes a controller, comprising:
- a pressure switch diagnostic system having first, second, third and fourth pressure switches each having a high and a low logic state;
- first and second logic valves each movable between a respective first position and second position;
- first, second, third and fourth trim valves each movable between a respective first position and second position;
- wherein two of the pressure switches are each multiplexed to report one of the high logic state and the low logic state to the controller in accordance with a relatively high and a relatively low fluid pressure, respectively, at a respective one of two of the trim valves corresponding with the position of the respective one of two of the trim valves and the position of the first logic valve;
- thereby enabling a determination of a change in position or a failure to change position of the respective one of two of the trim valves or the first logic valve;
- and
- wherein the other two of the pressure switches are each multiplexed to report one of the high and the low logic state to the controller in accordance with a relatively high and a relatively low fluid pressure, respectively, at a respective one of the other two trim valves corresponding with the position of the respective one of the other two trim valves and the position of the second logic valve;
- thereby enabling a determination of a change in position or a failure to change position of the respective one of the other two trim valves or of the second logic valve.
6 more elements
An electro-hydraulic control system comprising:
- five trim valves;
- three logic valves;
- wherein each of the trim valves and logic valves is selectively movable between respective first and second positions;
- a three position dog-clutch actuator valve selectively movable between reverse, neutral and forward positions;
- a diagnostic system including eight pressure switches in signal communication with a controller, each operable to report a logic state to the controller indicative of a position of at least one of the trim valves, the logic valve and the dog clutch actuator valve;
- and wherein some of the pressure switches are multiplexed in selective fluid communication with more than one of the trim valves, the logic valve and the dog clutch actuator valve to report logic states indicative of the positions of more than one valve.
3 more elements
An electro-hydraulic control system in combination with a transmission comprising:
- five trim valves;
- three logic valves;
- wherein each of the trim valves and logic valves is selectively movable between respective first and second positions;
- a three position dog-clutch actuator valve selectively movable between reverse, neutral and forward positions;
- a diagnostic system including eight pressure switches in signal communication with a controller, each operable to report a logic state to the controller indicative of a position of at least one of the trim valves, the logic valve and the dog clutch actuator valve;
- and wherein some of the pressure switches are multiplexed in selective fluid communication with more than one of the trim valves, the logic valve and the dog clutch actuator valve to thereby be operable to report logic states indicative of the positions of more than one of the valves;
- and
- wherein the torque-transmitting mechanisms include seven torque-transmitting mechanisms and the dog clutch selectively engagable in different combinations to provide at least nine forward speed ratios and two reverse speed ratios;
- and wherein the transmission is a countershaft transmission.
6 more elements
Dependencies are inferred from the claim text.