Method and apparatus for slip mode control of automatic clutch

• US 5,630,773 A
• Filed: 02/02/1996
• Issued: 05/20/1997
• Est. Priority Date: 02/02/1996
• Status: Expired due to Term

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Chan, Kwok W., Slicker, James M.
• Primary Examiner(s): Marmor, Charles A.
• Assistant Examiner(s): Kwon, Peter T.
• Application Number:
  US08/597,573
• Time in Patent Office: 473 Days
• Field of Search: 477/166, 477/174, 477/175, 477/176, 477/180
• US Class Current: 477/176
• CPC Class Codes: B60P 7/0807 Attachment points
• CPC Class Codes: B60W 2050/0011 Proportional Integral Differential [PID] controller
• CPC Class Codes: B60W 2050/0012 Feedforward or open loop systems
• CPC Class Codes: B60W 2710/025 Clutch slip, i.e. difference between input and output speeds
• CPC Class Codes: F16D 2500/10412 Transmission line of a vehicle
• CPC Class Codes: F16D 2500/1045 Friction clutch
• CPC Class Codes: F16D 2500/1115 Racing
• CPC Class Codes: F16D 2500/3021 Angle
• CPC Class Codes: F16D 2500/3026 Stroke
• CPC Class Codes: F16D 2500/30406 Clutch slip
• CPC Class Codes: F16D 2500/30415 Speed of the input shaft
• CPC Class Codes: F16D 2500/30426 Speed of the output shaft
• CPC Class Codes: F16D 2500/3067 Speed of the engine
• CPC Class Codes: F16D 2500/30816 Speed of the input shaft
• CPC Class Codes: F16D 2500/30825 Speed of the output shaft
• CPC Class Codes: F16D 2500/31426 Brake pedal position
• CPC Class Codes: F16D 2500/3144 Accelerator pedal position
• CPC Class Codes: F16D 2500/50239 Soft clutch engagement
• CPC Class Codes: F16D 2500/50293 Reduction of vibrations
• CPC Class Codes: F16D 2500/50858 Selecting a Mode of operation
• CPC Class Codes: F16D 2500/70252 : Clutch torque
• CPC Class Codes: F16D 2500/7041 : Position
• CPC Class Codes: F16D 2500/70472 : Input shaft speed
• CPC Class Codes: F16D 2500/70626 : PID control
• CPC Class Codes: F16D 2500/70642 : Inverse model
• CPC Class Codes: F16D 2500/70668 : Signal filtering
• CPC Class Codes: F16D 48/06 : Control by electric or electronic means, e.g. of fluid pressure
• CPC Class Codes: F16D 48/066 : Control of fluid pressure, e.g. using an accumulator F16D48/062, F16D48/068 take precedence
• CPC Class Codes: F16H 63/46 : Signals to a clutch outside the gearbox

Abstract

An automatic clutch controller for a vehicle that reduces the oscillatory response to clutch engagement. The automatic clutch controller receives inputs from a throttle position sensor, an engine speed sensor and a transmission input speed sensor and develops a clutch actuation signal controlling a clutch actuator from disengaged to fully engaged. The clutch engagement signal at least partially engages the friction clutch in a manner to cause the measured transmission input speed to asymptotically approach engine speed employing an approximate inverse model of this oscillatory response. The automatic clutch controller develops a slip reference signal as a function of throttle position and engine speed and compares it to actual slip. The controller includes a PID regulator responsive to the difference of slip and slip reference, a prefilter operating on the resulting PID signal, and a compensator constructed to reduce the need for detailed particularization for individual vehicles or vehicle models by reducing the system closed loop sensitivity to vehicle parameter variations.

Claims

1. An automatic clutch control in a power train including an engine controlled by a throttle, a friction clutch having an input shaft connected to the engine and an output shaft connected to the input of a transmission, a throttle position sensor for producing a throttle signal, an engine speed sensor connected to the engine for generating an engine speed signal, a transmission input speed sensor connected to the output shaft of the friction clutch for generating a transmission input speed signal corresponding to the rotational speed of the output shaft of the friction clutch, a clutch actuator connected to the friction clutch for controlling engagement of the friction clutch from disengaged to fully engaged according to a clutch engagement signal, the control comprising:

a slip reference generator responsive to the throttle signal for producing a slip reference signal which is a function of throttle and engine speed;

a circuit for producing a slip error signal from the input speed, the engine speed, and the slip reference signals;

a PID (proportional-integral-differential) regulator responsive to the slip error signal to regulate the slip error; and

a control circuit responsive to the regulated slip error for generating a clutch engagement signal to minimize the slip error signal, whereby the slip is controlled according to the slip reference signal.

2. The invention as defined in claim 1 wherein the slip reference generator produces a slip reference signal which is a percentage of engine speed, the percentage decreasing with increasing throttle.

3. The invention as defined in claim 1 wherein the slip reference generator produces a slip reference signal which is 100% engine speed at 0% throttle and gradually diminishes to 0% engine speed at a determined throttle setting.

4. The invention as defined in claim 1 wherein the circuit for producing a slip error signal comprises a first algebraic summer for determining a slip signal from the difference of the engine speed signal and the input speed signal and a second algebraic summer for determining the slip error signal from the difference of the slip reference and the slip signals.

5. The invention as defined in claim 1 wherein the control circuit includes a compensator having a third order notch filter.

6. The invention as defined in claim 1 wherein the control includes a mode logic circuit defining:

an auto off mode for disabling the automatic control when throttle is substantially closed;

a touch point control mode for controlling the clutch to a touch point when the throttle is above a minimum setting;

a slip mode entered when the touch point is attained for actuating the automatic control circuit to control clutch slippage according to the throttle and engine speed signals; and

a lockup mode entered when an upshift occurs.

7. The invention as defined in claim 1 wherein the control circuit includes:

a compensator responsive to the regulated slip error to produce a compensated signal;

a feed forward circuit; and

means for summing the compensated signal and the feed forward output to produce the clutch engagement signal.

8. The invention as defined in claim 7 wherein the feedforward circuit includes;

a differentiating compensator responsive to the engine speed for producing a lead signal; and

an integrator responsive to the lead signal for producing an integrator signal, whereby the lead signal and the integrator signal comprise the feedforward output.

9. A method of automatic clutch control in a vehicle having a gear transmission including an input shaft driven through a friction clutch by an engine that is controlled by a throttle, and having a clutch actuation controller for actuating the friction clutch, wherein the friction clutch has engageable parts which initially touch and then progressively increase in torque transfer during actuation, the clutch actuation controller having automatic modes including slip mode and lockup mode, the method comprising the steps of:

measuring engine speed, transmission input speed, and throttle position and producing corresponding signals;

generating a slip reference signal as a function of engine speed and throttle signals;

determining a slip value by comparing the engine speed and the input speed;

determining slip error by comparing the slip reference and the slip value; and

controlling the clutch actuation to minimize the slip error.

10. The invention as defined in claim 9 wherein the slip reference signal comprises engine speed at zero throttle position and a gradually decreasing percentage of engine speed at greater throttle values to attain zero percentage at an intermediate throttle value.

11. The invention as defined in claim 9 wherein the slip reference signal comprises engine speed at zero throttle position and a gradually decreasing percentage of engine speed at greater throttle values to attain zero percentage at an intermediate throttle value;

and

when the slip reference is zero, controlling the clutch actuation in accordance with the engine speed.

12. The invention as defined in claim 9 wherein the step of controlling the clutch actuation comprises:

modifying the slip error by proportional and integral regulation of the slip error signal;

and generating a clutch engagement signal to minimize the slip error signal by modifying the difference of the input speed signal and the slip error signal.

13. The invention as defined in claim 9 wherein the step of controlling the clutch actuation comprises:

modifying the slip error by proportional and integral regulation of the slip error signal;

third order filtering the difference of the input speed signal and the slip error signal to produce a compensated signal;

differentiating the engine speed to produce a differential signal;

integrating the differential signal to produce an integrated signal; and

summing the compensated signal, the differential signal and the integrated signal to produce a clutch actuation signal.

14. The invention as defined in claim 9 wherein the step of controlling the clutch actuation comprises:

modifying the slip error by proportional and integral regulation of the slip error signal;

summing the input speed signal and the modified slip error signal; and

filtering the summed signals by a third order notch filter with notch frequency placed in the range of expected vibration frequencies.

15. The invention as defined in claim 9 including:

entering the slip mode after attaining touch point; and

exiting the slip mode and entering the lockup mode when a gear upshift occurs;

whereby the step of controlling the clutch actuation to minimize the slip error occurs only when in the slip mode.