Method of detecting filling of hydraulic clutch
AssigneeGM Global Technology Operations LLC
InventorsVijay A. Neelakantan, Bret M. Olson
Life of this patent
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Abstract
A method of detecting filling of a hydraulic cylinder and incipient full engagement of a hydraulically operated clutch of a vehicular transmission utilizes a pressure sensor disposed in a hydraulic line to the clutch cylinder which provides a signal that the hydraulic pressure has dropped as the clutch cylinder begins to fill and also that the pressure has returned to a substantially normal level. The pressure sensor may be a continuously variable output device such as an analog sensor, pulse width modulation (PWM) sensor, a similar device or, less desirably, a two state sensor. An iterative algorithm utilizes data from the sensor and a timer to determine when clutch fill is complete.
Claims19
A method of determining engagement of a friction clutch in a transmission comprising the steps of:
- providing a source of pressurized hydraulic fluid, a control valve, a proportional pressure sensor, a timer and a hydraulic clutch having a cylinder,
- providing a flow of pressurized fluid through said control valve to said clutch cylinder,
- sensing hydraulic fluid pressure supplied to said clutch cylinder per unit of time,
- determining when a change in said pressure per unit of time is less than a first predetermined value and said timer has timed a period greater than a second predetermined time, and
- providing a signal that said cylinder of said hydraulic clutch is filled and said clutch is engaged.
A method of determining achievement of a filled state of a hydraulic clutch in a transmission, comprising the steps of:
- providing a hydraulic pump, a hydraulic clutch having a cylinder, a fluid path providing communication between said pump and said cylinder and a valve for controlling fluid flow in said path such that opening said valve to fill said cylinder causes a reduction in fluid pressure in said path,
- providing a timer and a proportional pressure sensor in said path having an output,
- opening said valve,
- sensing hydraulic fluid pressure supplied to said hydraulic clutch cylinder per unit of time,
- determining when a change in said pressure per unit of time is less than a first predetermined value and said timer has timed a period greater than a second predetermined time, and
- providing an indication that said hydraulic clutch cylinder is filled and said clutch is engaged.
A method of determining a full state of a cylinder of a hydraulic friction clutch in a transmission, comprising the steps of:
- providing a hydraulic pump and a hydraulic friction clutch having a cylinder,
- providing a fluid communication passageway between said pump and said cylinder and a fluid control valve for controlling fluid flow in said passageway,
- providing a proportional pressure sensor for monitoring fluid pressure in said passageway between said valve and said cylinder and having an output and a timer for determining time elapsed after said fluid control valve is opened,
- opening said valve,
- sensing hydraulic fluid pressure in said fluid communication passageway per unit of time,
- determining when a derivative of said pressure per said unit of time is less than a first predetermined value and said timer has timed a period greater than a second predetermined time, and
- providing a signal that said hydraulic clutch cylinder is filled and said clutch is engaged.
Dependencies are inferred from the claim text.