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US 4,967,385 AGranted
Electronic control system for powershift transmission
AssigneeJ.I. Case Company
InventorsKevin L. Brekkestran, John C. Thomas
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AssigneeJ.I. Case Company
InventorsKevin L. Brekkestran, John C. Thomas
Estimating the term…
A microprocessor-based electronic control system for a powershift transmission having at least one proportional actuator, such as a solenoid-operated proportional valve, is disclosed. The controller operates a plurality of on-off solenoid valves and the solenoid-operated proportional valve to provide operator-selected gear shifts in both forward and reverse directions having controlled clutch engagements achieved by modulation of clutch engagement pressure by the proportional valve. The key parameters associated with the gradual clutch engagement are all easily varied by the controller, most under program control during operation, to provide for optimized clutch engagements for smooth gearshifts. The key parameters include: fast-fill clutch delay, initial clutch engagement pressure, rate of increase of clutch engagement pressure, and the length of the reduced pressure clutch engagement interval. The electronic controller also automatically modifies selected parameters in accordance with sensed changes in temperature, magnetic flux coupling between solenoids, and variations in the voltage supply provided to the series combination of the solenoid coil of proportional valve and its solenoid driver circuit. Preferred methods of operating the electronic controller and powershift transmission are also disclosed.
In an apparatus having at least one actuator means for adjusting at least one parameter within the apparatus in response to a first electrical signal which is an alternating electrical signal, the actuator means including a solenoid coil to which the first electrical signal is applied, a method for compensating for changes in temperature of the apparatus, comprising the steps of:
In an apparatus having at least one actuator means for adjusting at least one parameter within the apparatus in response to a first electrical signal which is an alternating electrical signal, the actuator means including a solenoid coil to which the first electrical signal is applied, an electronic control system for compensating for changes in temperature of the apparatus, comprising:
In an apparatus having at least one actuator means for adjusting at least one parameter within the apparatus in response to a first electrical signal which is an alternating signal, the actuator means including a solenoid coil to which the first electrical signal is applied, a method of determining the approximate operating temperature of the apparatus relative to a nominal operating temperature, comprising the steps of:
In an apparatus having at least one actuator means for adjusting at least one parameter within the apparatus in response to a first electrical signal which is an alternating electrical signal the actuator means including a solenoid coil to which the first electrical signal is applied, a temperature sensing system for determining the approximate operating temperature of the apparatus relative to a predetermined temperature, the system comprising:
Dependencies are inferred from the claim text.