Solenoid operated clutch engagement
AssigneeFord Motor Company
InventorsJames P. McCarthy, Richard E. Byler
Life of this patent
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Abstract
An electrical solenoid operates a three-way valve having a vent port, a port connected to a source of high pressure hydraulic fluid and a port connection to a pilot valve. A check valve supplied from a source of low pressure hydraulic fluid is connected to the cylinder of a clutch or servo of an automatic transmission when a pilot valve opens this communication upon energizing the solenoid coil. The clutch cylinder is depressurized through the pilot valve to the vent port of the solenoid-operated valve.
Claims11
A hydraulic control system for pressurizing and venting the cylinder of an automatic transmission clutch comprising:
- a source of fluid at low pressure;
- a source of fluid at higher pressure;
- a first valve for communicating the low pressure source to an outlet port and for closing said communication when the pressure in the clutch cylinder reaches a first predetermined pressure;
- a second valve for communicating the outlet port to the clutch cylinder when the high pressure source is connected to a control chamber of the second valve;
- and
- a third valve including an electrical solenoid having a valve element whose position is controlled by the state of the electrical solenoid, for opening the high pressure source to the control chamber, closing the high pressure source from the control chamber and venting the control chamber.
A hydraulic control system for hydraulically engaging and disengaging an automatic transmission clutch having a clutch cylinder comprising:
- a source of fluid at low pressure;
- a source of fluid at high pressure;
- a first valve for opening the low pressure source to an outlet port and for closing said communication if the pressure within the clutch cylinder reaches a predetermined value;
- a second valve for opening the outlet port to the clutch cylinder if the high pressure source is connected to a control chamber of the second valve, and for closing said communication if the clutch cylinder pressure reaches a second predetermined pressure;
- and
- a third valve having a valve element whose position is controlled by the state of an electrical solenoid adapted to open the high pressure source to the control chamber and to close the high pressure source from the control chamber, which closure vents the control chamber.
Dependencies are inferred from the claim text.