Control of powertrain smoothness using output torque sensing and input torque control

• US 20050101435A1
• Filed: 11/12/2003
• Published: 05/12/2005
• Est. Priority Date: 11/12/2003
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Cowan, Ronald
• Granted Patent: US 6,991,584 B2
• Time in Patent Office: Days
• US Class Current: 477/83
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2710/027 Clutch torque
• CPC Class Codes: B60W 2710/0605 Throttle position
• CPC Class Codes: B60W 2710/0622 Air-fuel ratio
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 30/18 Propelling the vehicle
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: F16H 2306/42 Changing the input torque to the transmission
• CPC Class Codes: F16H 2306/44 Removing torque from current gears
• CPC Class Codes: F16H 2306/52 Applying torque to new gears
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: F16H 63/502 for smoothing gear shifts

Abstract

An automatic transmission ratio shift and shift feel control system and method for a powertrain having an engine, multiple-ratio gearing controlled by friction elements actuated by hydraulic pressure, an output shaft torque sensor producing a signal representing the magnitude of current output torque, an electronic controller for controlling the target output torque based on the current output torque, increasing the torque capacity of the oncoming friction element and decreasing the torque capacity of the offgoing friction element after a gear ratio change is initiated. During the inertia phase of the ratio change, the controller controls the engine speed to follow a predetermined rate of change of input speed. The strategy employs an electronic throttle and closed loop engine torque control and closed loop engine speed control at various phases of the gear shift, to improve shift feel. Various engine parameters, including throttle position, ignition timing, engine air-fuel ratio, and engine airflow, control engine torque and speed, are used to control input torque or input speed, depending upon the shift phase.

Claims

1. A method for controlling a gear ratio change from a current gear to a next gear in an automatic transmission coupled to an engine by disengaging an offgoing friction element and engaging an oncoming friction element, the transmission having an input, input speed, output, and output torque, the method comprising the steps of:

repetitively determining a target output torque;

initiating a gear ratio change from the current gear to the next gear;

repetitively increasing a torque capacity of the oncoming friction element toward a magnitude of torque transmitted by the oncoming friction element when the target output torque is produced in the next gear;

decreasing a torque capacity of the offgoing friction element to a predetermined torque capacity;

producing an indication of the current output torque; and

in response to the indication, adjusting an operating parameter of the engine to control the engine torque such that the output torque is maintained substantially at the target output torque.

2. The method of claim 1 wherein the target output torque current is determined with reference to a position of an accelerator pedal and a current vehicle speed.

3. The method of claim 1 wherein the target output torque current is determined with reference to a position of an accelerator pedal, a position of a shift lever, and a current vehicle speed.

4. The method of claim 1 wherein the step of decreasing a torque capacity of the offgoing friction element, further includes:

determining the magnitude of torque transmitted by the offgoing friction element when the target output torque is produced at the output in the current gear; and

decreasing the torque capacity of the offgoing friction element to a magnitude that is equal to or greater than the magnitude of torque transmitted by the offgoing friction element when the target output torque is produced at the output in the current gear.

5. The method of claim 1 wherein the step of decreasing a torque capacity of the offgoing friction element, further includes:

decreasing the torque capacity of the offgoing friction element to a magnitude such that the offgoing friction element does not slip when the target output torque is produced at the output in the current gear.

6. The method of claim 1 wherein the step of decreasing a torque capacity of the offgoing friction element, further includes:

producing an second indication when the magnitude of torque transmitted by the offgoing friction element reaches zero while the target output torque is produced at the output in the current gear;

producing a third indication when a current gear ratio produced by the transmission is substantially equal to the gear ratio produced by the transmission in the next gear; and

decreasing the torque capacity of the offgoing friction element when the second and third indications are present.

7. The method of claim 1, further comprising:

producing an second indication when the magnitude of torque transmitted by the offgoing friction element reaches zero while the target output torque is produced at the output in the current gear;

producing a third indication when a current gear ratio produced by the transmission is substantially equal to the gear ratio produced by the transmission in the next gear; and

adjusting an operating parameter of the engine to control the engine speed to a predetermined speed when the second and third indications are present.

8. The method of claim 1 wherein said engine operating parameter is an engine airflow.

9. The method of claim 1 wherein said engine operating parameter is a throttle position of the engine.

10. The method of claim 1 wherein said engine operating parameter is an ignition timing.

11. The method of claim 1 wherein said engine operating parameter is an engine air-fuel ratio.

12. A system for controlling gear ratio changes, comprising:

an internal combustion engine having an engine speed and engine torque;

an automatic transmission driveably coupled to the engine, the transmission having an input, input speed, output, and output torque at the output, an offgoing friction element, an oncoming friction element, a current gear, and a next gear, produced by disengaging the offgoing friction element and engaging the oncoming friction element;

a torque sensor secured to the output for producing an indication of the magnitude of a current output torque; and

a controller determining a target output torque, increasing a torque capacity of the oncoming clutch toward a magnitude of torque carried by the oncoming clutch when the target output torque is produced at the output in the next gear, decreasing a torque capacity of the offgoing friction element clutch to a predetermined torque capacity, and in response to the indication, adjusting an operating parameter of the engine to control the engine torque such that the output torque is maintained at or below the target output torque.

13. The system of claim 12, further comprising:

a first sensor producing a signal representing the position of an accelerator pedal;

a second sensor producing a signal representing a current vehicle speed; and

wherein the controller determines the target output torque with reference to the position of an accelerator pedal and current vehicle speed.

14. The system of claim 12, further comprising:

a controller determining the magnitude of torque transmitted by the offgoing friction element when the target output torque is produced at the output in the current gear, and decreasing the torque capacity of the offgoing friction element to a magnitude that is equal to or greater than the magnitude of torque transmitted by the offgoing friction element when the target output torque is produced at the output in the current gear.

15. The system of claim 12, further comprising:

a controller for decreasing the torque capacity of the offgoing friction element to a magnitude such that the offgoing friction element does not slip when the target output torque is produced at the output in the current gear.

16. The system of claim 12, further comprising:

a controller producing an second indication when the magnitude of torque transmitted by the offgoing friction element reaches zero while the target output torque is produced at the output in the current gear, producing a third indication when a current gear ratio produced by the transmission is substantially equal to the gear ratio produced by the transmission in the next gear, and decreasing the torque capacity of the offgoing friction element when the second and third indications are present.

17. The system of claim 12, further comprising:

a controller producing an second indication when the magnitude of torque transmitted by the offgoing friction element reaches zero while the target output torque is produced at the output in the current gear, producing a third indication when a current gear ratio produced by the transmission is substantially equal to the gear ratio produced by the transmission in the next gear, and adjusting an operating parameter of the engine to control the engine speed to a predetermined speed when the second and third indications are present.

18. The system of claim 12 wherein the engine operating parameter adjusted by the controller is an engine airflow.

19. The system of claim 12 wherein the engine operating parameter adjusted by the controller is a throttle position of the engine.

20. The system of claim 12 wherein the engine operating parameter adjusted by the controller is an ignition timing.

21. The method of claim 12 wherein the engine operating parameter adjusted by the controller is an engine air-fuel ratio.