CLUTCH HOLD LEVEL AS A FUNCTION OF TORQUE
First Claim
1. A method of controlling a transmission having a plurality of hydraulic clutches for shifting between one or more transmission ratios, the method comprising:
- determining to execute a shift of the transmission between a first ratio associated with an off-going hydraulic clutch of the transmission, which is currently engaged, and a second ratio associated with an on-coming hydraulic clutch of the transmission, which is currently disengaged;
commanding a decrease of hydraulic pressure to the off-going hydraulic clutch to begin disengagement of the off-going hydraulic clutch;
calculating a hold level command for the on-coming hydraulic clutch based upon a torque experienced by the transmission during the shift of the transmission; and
commanding, with respect to the on-coming hydraulic clutch, a sequence of clutch phases to occur at predetermined times regardless of the torque experienced by the transmission during the shift of the transmission, the sequence of clutch phases including a pulse phase, a hold phase that includes applying the calculated hold level command to the on-coming hydraulic clutch, and a modulation phase to fully engage the on-coming hydraulic clutch.
1 Assignment
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Accused Products
Abstract
A system and method for controlling a hydraulic transmission uses a clutch fill profile having a hold level that varies as a function of torque. A pressure required for an on-coming clutch to hold the gear of the off-going clutch without a flare or over-speed condition is calculated. This pressure approximates the pressure of the on-coming clutch when a disengage command with respect to the off-going clutch is reached. The pulse and hold phases for the clutch are executed at times that are constant from shift to shift and do not vary as a function of torque or slip.
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Citations
20 Claims
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1. A method of controlling a transmission having a plurality of hydraulic clutches for shifting between one or more transmission ratios, the method comprising:
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determining to execute a shift of the transmission between a first ratio associated with an off-going hydraulic clutch of the transmission, which is currently engaged, and a second ratio associated with an on-coming hydraulic clutch of the transmission, which is currently disengaged; commanding a decrease of hydraulic pressure to the off-going hydraulic clutch to begin disengagement of the off-going hydraulic clutch; calculating a hold level command for the on-coming hydraulic clutch based upon a torque experienced by the transmission during the shift of the transmission; and commanding, with respect to the on-coming hydraulic clutch, a sequence of clutch phases to occur at predetermined times regardless of the torque experienced by the transmission during the shift of the transmission, the sequence of clutch phases including a pulse phase, a hold phase that includes applying the calculated hold level command to the on-coming hydraulic clutch, and a modulation phase to fully engage the on-coming hydraulic clutch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A hydraulic clutch control system for a transmission, comprising:
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an off-going clutch disposed to engage a first ratio of the transmission; an on-coming clutch disposed to engage a second ratio of the transmission; a first electro-hydraulic control valve associated with the off-going clutch; a second electro-hydraulic control valve associated with the on-coming clutch; and a clutch controller operably associated with the first and second electro-hydraulic control valves, wherein the clutch controller is disposed to; determine an execution of a shift of the transmission between the first ratio and the second ratio when the first ratio is engaged; command a decrease of hydraulic pressure to the off-going clutch to begin disengagement of the off-going clutch from the first ratio; calculate a hold level command for the on-coming clutch based upon a torque experienced by the transmission during the shift of the transmission; and command, with respect to the on-coming clutch, a sequence of clutch phases to occur at predetermined times regardless of the torque experienced by the transmission during the shift of the transmission, the sequence of clutch phases including a pulse phase, a hold phase that includes applying the calculated hold level command to the on-coming clutch, and a modulation phase to fully engage the on-coming clutch. - View Dependent Claims (13, 14, 15, 16)
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17. A computer-readable medium having thereon computer-executable instructions for shifting between one or more transmission ratios within a transmission having a plurality of hydraulic clutches, the computer-executable instructions comprising:
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instructions for determining to execute a shift of the transmission between a first ratio associated with an off-going hydraulic clutch of the transmission, which is currently engaged, and a second ratio associated with an on-coming hydraulic clutch of the transmission, which is currently disengaged; instructions for commanding a decrease of hydraulic pressure to the off-going hydraulic clutch to begin disengagement of the off-going hydraulic clutch; instructions for calculating a hold level command for the on-coming hydraulic clutch based upon a torque experienced by the transmission during the shift of the transmission; and instructions for commanding, with respect to the on-coming hydraulic clutch, a sequence of clutch phases to occur at predetermined times regardless of the torque experienced by the transmission during the shift of the transmission, the sequence of clutch phases including a pulse phase, a hold phase that includes instructions for applying the calculated hold level command to the on-coming hydraulic clutch, and a modulation phase to fully engage the on-coming hydraulic clutch. - View Dependent Claims (18, 19, 20)
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Specification