Modification of shifting characteristics based upon shifting direction and drive train load
AssigneeCase Corporation
InventorsJeffrey S. Milender, Thomas G. Lykken, Bradley A. Kuczmarski
Life of this patent
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Abstract
An apparatus and method for controlling a plurality of clutches in a powershift transmission. The transmission is coupled to an engine of an off-road vehicle. The method includes receiving a shift command having a shift direction. Clutch timing is selected based on the shift direction. Using the selected shift timing, on-coming clutches are engaged in sequence with disengagement of off-going clutches to achieve smooth shifting.
Claims32
A method of controlling a plurality of clutches in a powershift transmission, the transmission being coupled to an engine of a work vehicle, the method comprising:
- receiving a shift command having a shift direction;
- selecting clutch timing based on the shift direction of the received shift command including selecting a variable time delay between the engagement of an on-coming clutch and the disengagement of an off-going clutch;
- sensing vehicle load;
- engaging an on-coming clutch;
- and
- disengaging an off-going clutch before, after, or during engaging the on coming clutch, wherein the time delay between engaging the on-coming clutch and disengaging the off-going clutch is based on the selected clutch timing, wherein the selected clutch timing is further based on the sensed vehicle load.
An apparatus for controlling operation of a powershift transmission, the transmission being coupled to an engine of an off-road vehicle, the apparatus comprising:
- a sensor for sensing vehicle load;
- a plurality of clutches;
- a plurality of on/off valves for controlling fluid flow to the clutches;
- and
- a table of clutch parameters, wherein the clutch parameters correspond to the vehicle load and clutch characteristics, whereby clutch parameters indicate sequencing of the on/off valves thereby providing smooth shifting in the transmission said parameters including data indicative of at least two different selectable intervals between an on-coming clutch engagement and an off-going clutch disengagement for each of said plurality of clutches.
An electronic transmission control system for controlling clutch sequencing in a powershift transmission having a plurality of clutches, the transmission being coupled to an engine of a work vehicle, the control system comprising:
- a sensor configured to sense vehicle load and to provide a load signal;
- a plurality of tables having clutch timing parameters said plurality of tables including data indicative of at least two different selectable intervals between an on-coming clutch engagement and an off-going clutch disengagement for each of said plurality of clutches;
- a controller configured to receive the load signal and to select one of the plurality of tables based on the load signal, wherein each table corresponds to a first range of vehicle loads during an upshift and a second range of vehicle loads during a downshift, the first and second ranges being different, wherein the controller controls the sequencing of the clutches based on a clutch timing parameter from the selected table.
An apparatus for controlling a plurality of clutches in a powershift transmission the transmission being coupled to an engine of an off-road vehicle, the apparatus comprising:
- means for receiving a shift command;
- means for selecting clutch timing, wherein the selected clutch timing is dependent upon shift direction of the received shift command;
- means for sensing vehicle load, wherein the selected clutch timing is further dependent upon the sensed vehicle load;
- means for engaging an on-coming clutch;
- and
- means for disengaging an off-going clutch, for the timing between disengaging the off-going clutch and engaging the on-coming clutch being defined by the selected clutch timing, said means for selecting at least including data indicative of at least two different selectable intervals between an on-coming clutch engagement point and an off-going clutch disengagement point for each of said plurality of clutches.
Dependencies are inferred from the claim text.