Feedforward control for automatic transmission torque converter bypass clutch slip
First Claim
1. A system for controlling a torque converter bypass clutch in an automatic transmission producing an operating gear ratio connected to an engine controlled by a variable position throttle, comprising:
- a torque converter having an impeller adapted for connection to the engine, a turbine adapted for hydrokinetic connection to the impeller, and a clutch whose full engagement mechanically connects the impeller and turbine and whose full release mechanically disconnects the impeller and turbine, partial engagement of the clutch permitting a difference in speed or slip between the impeller and turbine;
a source of hydraulic pressure;
an electrical solenoid-operated valve opening and closing communication between the pressure source and the clutch, for producing pressure of variable magnitude in the clutch in response to a signal applied to the solenoid;
means for producing signals representing impeller speed, turbine speed, and throttle position;
feedback control means supplied with a slip error signal representing the difference between actual slip and commanded slip for producing a first control signal;
feedforward control means supplied with a signal representing impeller speed and throttle position for producing a second control signal whose phase and gain are inverted in comparison to a phase and gain of a clutch pressure response to a signal applied to the solenoid;
means for summing the first and second control signals and producing a corrected control signal therefrom;
means for controlling the speed difference across the torque converter by supplying said corrected control signal to the solenoid.
2 Assignments
0 Petitions
Accused Products
Abstract
A powertrain including an engine controlled by the position of a throttle valve, a hydrodynamic torque converter having a bypass clutch, multiple ratio automatic transmission connected to the drive wheels of the vehicle, a solenoid-operated hydraulic valve that supplies pressurized fluid to engage and release the bypass clutch, is controlled by operation of a feedforward control system. An engine math model produces a signal representing the net torque output by the engine, which signal is applied as input to an inverse mathematical model of the solenoid-operated valve that supplies hydraulic fluid to the bypass clutch. The unique relationship of phase to gain, the frequency response of the solenoid valve, is inverted to remove the effects of delay and transient rise time. Torque converter slip error determined as the difference between torque converter impeller speed and turbine speed, is applied as input to a PID compensated feedback control whose output is summed with the inverse of the solenoid valve frequency response to produce a duty cycle supplied to the solenoid of the bypass pressure hydraulic valve.
58 Citations
13 Claims
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1. A system for controlling a torque converter bypass clutch in an automatic transmission producing an operating gear ratio connected to an engine controlled by a variable position throttle, comprising:
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a torque converter having an impeller adapted for connection to the engine, a turbine adapted for hydrokinetic connection to the impeller, and a clutch whose full engagement mechanically connects the impeller and turbine and whose full release mechanically disconnects the impeller and turbine, partial engagement of the clutch permitting a difference in speed or slip between the impeller and turbine; a source of hydraulic pressure; an electrical solenoid-operated valve opening and closing communication between the pressure source and the clutch, for producing pressure of variable magnitude in the clutch in response to a signal applied to the solenoid; means for producing signals representing impeller speed, turbine speed, and throttle position; feedback control means supplied with a slip error signal representing the difference between actual slip and commanded slip for producing a first control signal; feedforward control means supplied with a signal representing impeller speed and throttle position for producing a second control signal whose phase and gain are inverted in comparison to a phase and gain of a clutch pressure response to a signal applied to the solenoid; means for summing the first and second control signals and producing a corrected control signal therefrom; means for controlling the speed difference across the torque converter by supplying said corrected control signal to the solenoid. - View Dependent Claims (2, 3, 4, 5)
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6. A system for controlling a torque converter bypass clutch in an automatic transmission connected to an engine controlled by a variable position throttle, comprising:
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a torque converter having an impeller connected to the engine, a turbine adapted for hydrokenetic connection to the impeller, and a clutch whose full engagement mechanically connects the impeller and turbine and whose full release mechanically disconnects the impeller and turbine, partial engagement of the clutch permitting a difference in speed or slip between the impeller and turbine; a source of hydraulic pressure; an electrical solenoid-operated valve opening and closing communication between the pressure source and the clutch, for producing pressure of variable magnitude in the clutch in response to a signal applied to the solenoid; means for producing signals representing impeller speed, turbine speed, and throttle position; feedback control means supplied with a slip error signal representing the difference between actual slip and commanded slip for producing a first control signal; feedforward control means supplied with a signal representing impeller speed and throttle position including means producing a signal representing engine torque and means response to the engine torque signal for producing a second control signal whose phase and gain are inverted in comparison to the phase and gain of the clutch pressure response to a signal applied to the solenoid; means for summing the first and second control signals and producing a corrected control signal therefrom; means for controlling slip across the torque converter by supplying said corrected control signal to the solenoid. - View Dependent Claims (7, 8, 9)
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10. A method for controlling a torque converter clutch operating in an automatic transmission connected to an engine controlled by a variable position throttle the torque converter having an impeller to the engine, a turbine adapted for hydrokenetic connection to the impeller, and a clutch whose full engagement mechanically connects the impeller and turbine and whose full release mechanically disconnects the impeller and turbine, partial engagement of the clutch permitting a difference in speed or slip between the impeller and turbine, an electrical solenoid-operated valve communicating with the clutch, comprising the steps of:
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producing pressure of variable magnitude in the clutch by opening and closing communication between a source of hydraulic pressure and the clutch in response to a signal applied to the solenoid; producing signals representing impeller speed, turbine speed, and throttle position; producing a first control signal in response to a slip error signal representing the difference between actual slip and commanded slip; producing a second control signal whose phase and gain are inverted in relation to the phase and gain of the clutch pressure in response to a signal applied to the solenoid; summing the first and second control signals and producing a corrected control signal therefrom; controlling the speed difference across the torque converter by supplying said corrected control signal to the solenoid. - View Dependent Claims (11, 12, 13)
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Specification