Engagement control logic for an automatic transmission clutch with adaptive engagement feel

• US 6,253,140 B1
• Filed: 08/04/1999
• Issued: 06/26/2001
• Est. Priority Date: 08/04/1999
• Status: Expired due to Term

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Vodicka, Ronald James, Kuhn, Howard Cecil, Jain, Pramod Kumar
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US09/366,416
• Time in Patent Office: 692 Days
• Field of Search: 701/51, 701/53, 701/54, 701/58, 701/60, 701/66, 701/67, 701/68, 477/115, 477/120, 477/143, 477/154, 477/156, 477/176, 477/169, 477/174, 477/70, 477/77, 477/78, 477/79, 477/83, 477/86, 477/166, 477/171, 477/173, 192/3.3, 192/3.31, 192/3.58, 192/103.C, 475/123, 475/128, 475/63, 475/65
• US Class Current: 701/67
• CPC Class Codes: F16D 2500/1026 Hydraulic
• CPC Class Codes: F16D 2500/1087 Planetary gearing
• CPC Class Codes: F16D 2500/3024 Pressure
• CPC Class Codes: F16D 2500/50653 Gearing shifting without the interruption of drive
• CPC Class Codes: F16D 2500/50684 Torque resume after shifting
• CPC Class Codes: F16D 2500/70426 Clutch slip
• CPC Class Codes: F16D 2500/70605 Adaptive correction; Modifying control system parameters, e.g. gains, constants, look-up tables
• CPC Class Codes: F16D 2500/70626 PID control
• CPC Class Codes: F16D 48/06 Control by electric or electronic means, e.g. of fluid pressure
• CPC Class Codes: F16H 2061/0087 Adaptive control, e.g. the control parameters adapted by learning
• CPC Class Codes: F16H 2061/0488 during range shift from neutral (N) to drive (D)
• CPC Class Codes: F16H 59/46 dependent on a comparison between speeds
• CPC Class Codes: F16H 61/061 using electric control means

Abstract

An adaptive control system and method for direct clutch engagement control for an automatic transmission including a micro-controller that receives and stores input data from driveline sensors and executes transmission clutch control logic. The micro-controller develops output signals in real time and transfers the signals to a driver circuit that controls solenoids that enable clutch engagement. The signals for establishing clutch pressure buildup are delivered to a driver circuit that produces hydraulic pressure at the clutch to achieve a smooth torque and speed transition for the torque input elements of the transmission. Adaptive pressure values are stored in a keep-alive memory. The pressure values are adjusted values based on the result of previous engagements. This compensates for driveline variables such as changes in coefficients of friction, spring loads, clutch wear, etc., whereby engagement cycle time is reduced and actual pressure buildup rate is maintained close to desired value to achieve a desired slip change rate, thereby achieving consistent, improved engagement quality.

Claims

1. An electronic control system for controlling the engagement of a pressure-operated friction clutch of a multiple-ratio transmission in an automotive vehicle driveline with an output shaft and a throttle-controlled engine, the system comprising a microprocessor, the microprocessor being characterized by sequential execution of software instructions in a continuous control loop in response to driveline input control data;

a plurality of driveline sensors including an engine throttle position sensor, a transmission range selector position sensor, an output shaft speed sensor and an engine speed sensor, the microprocessor having an input signal conditioner with signal flow paths for receiving input and feedback signals from the sensors;

the microprocessor also having a calculation unit for computing transmission control parameters including transmission input torque, friction clutch slip and vehicle speed based on the input and feedback signals;

a base control unit of the microprocessor receiving computed vehicle speed, actual slip of the friction clutch and transmission input torque;

the calculation unit detecting changes in system control parameters and including means for developing a controlled friction clutch engagement pressure during vehicle startup as a function of the transmission control parameters;

means for recording the system control parameter changes during each control loop of the microprocessor, and an adaptive control unit for modifying the friction clutch engagement pressure calculated in a current control loop of the microprocessor in accordance with the recorded control parameters.

2. An electronic control system as set forth in claim 1 wherein the engine speed sensor and the output shaft speed sensor communicate with the calculation unit in a closed-loop fashion whereby the calculation unit determines in real time output signals indicating a vehicle speed signal, a clutch slip signal and commanded and actual friction clutch slip rate signals, output signals of the calculation unit being communicated to the base control unit.

3. An electronic control system for controlling the engagement of a friction clutch of a multiple-ratio transmission in an automotive vehicle driveline during vehicle startup, the driveline having an output shaft and a throttle-controlled engine, the transmission having a torque converter with an impeller connected drivably to the engine and a turbine drivably connected to the friction clutch;

the control system comprising a microprocessor including a calculation unit, a base control unit, memory storage registers and an adaptive control unit;

a plurality of driveline sensors including an engine throttle position sensor, a transmission range selector position sensor, an output shaft speed sensor, a turbine speed sensor, and an engine speed sensor;

the microprocessor having an input signal conditioner with signal flow paths for receiving input and feedbacks signals from the sensors including an engine speed signal, a turbine speed signal and an output shaft speed signal;

the microprocessor further having a calculation unit for computing transmission input torque, friction clutch slip and vehicle speed based on the input and feedback signals, the microprocessor being characterized by sequential execution of software instructions in a continuous control loop in response to driveline input control data;

the calculation unit detecting commanded slip rate of the friction clutch and comparing it to the actual slip rate to detect an error;

a base control unit of the microprocessor receiving computed vehicle speed, slip rate error, transmission input torque and friction clutch slip and computing a friction clutch control signal whereby the friction torque capacity of the clutch is controlled;

memory storage registers of the microprocessor including memory storage registers being in communication with the base control unit for storing clutch engagement parameters during each control loop of the microprocessor;

the microprocessor including further an adaptative control unit for modifying the friction clutch engagement signal developed by the control unit during a current control loop of the microprocessor by adjusting clutch pressure values in accordance with control parameters stored in the memory storage registers during a preceding control loop thereby compensating driving friction clutch engagement for a base control unit of the microprocessor, the base control unit receiving computed vehicle speed, slip rate error, transmission input torque and friction clutch slip and computing a friction clutch control signal whereby the friction torque capacity of the clutch is controlled;

the microprocessor adjusting clutch pressure values in accordance with control parameters stored in memory storage registers during the preceding control loop thereby compensating during friction clutch engagement for changes in system control parameters.

4. An electronic control system set forth in claim 3 wherein the engine speed sensor, the turbine speed sensor, and the output shaft speed sensor communicate with the calculation unit in a closed-loop fashion whereby the calculation unit determines in real time output signals indicating a vehicle speed signal, a clutch slip signal and commanded and actual friction clutch slip rate signals, output signals of the calculation unit being communicated to the base control unit.

5. A method for controlling engagement of a pressure-operated friction clutch of a multiple-ratio automatic transmission in a vehicle driveline having a throttle-controlled engine and an output shaft, the method comprising:

detecting driveline variables including throttle position, output shaft speed, engine speed, and transmission ratio;

calculating control parameters including friction clutch slip, transmission input torque, commanded clutch slip rate, actual clutch slip rate, slip rate error, and vehicle speed as a function of the driveline control variables;

determining desired clutch pressure as a function of current ratio, transmission input torque and vehicle speed;

executing a friction clutch engagement cycle by initiating an engagement start mode wherein clutch pressure is commanded to effect incipient clutch engagement;

initiating a torque transfer phase of the engagement cycle to control clutch pressure by increasing clutch pressure in the engagement start phase at a controlled rate; and

initiating a slip change phase of the engagement cycle by controlling clutch pressure in a closed-loop fashion thereby decreasing clutch slip to a desired value over a predetermined time.

6. The method set forth in claim 5 wherein the slip change phase is followed during the engagement cycle by an engagement end phase whereby the commanded clutch pressure is increased nonlinearly until it reaches the commanded pressure thereby effecting full clutch engagement without an inertia torque disturbance during the engagement cycle.

7. An electronic control system for controlling the engagement of a friction clutch of a multiple-ratio transmission in an automotive vehicle driveline during vehicle startup, the driveline having an output shaft and a throttle-controlled engine, the transmission having a torque converter with an impeller connected drivably to the engine and a turbine drivably connected to the friction clutch;

the control system comprising a microprocessor including a calculation unit, a base control unit, memory storage registers and an adaptive control unit;

a plurality of driveline sensors including an engine throttle position sensor, a transmission range selector position sensor, an output shaft speed sensor, a turbine speed sensor, and an engine speed sensor;

the microprocessor having an input signal conditioner with signal flow paths for receiving input and feedbacks signals from the sensors including an engine speed signal, a turbine speed signal and an output shaft speed signal;

the microprocessor further having a calculation unit for computing transmission input torque, friction clutch slip and vehicle speed based on the input and feedback signals, the microprocessor being characterized by sequential execution of software instructions in a continuous control loop in response to driveline input control data;

the calculation unit detecting commanded slip rate of the friction clutch and comparing it to the actual slip rate to detect an error; and

a base control unit of the microprocessor receiving computed vehicle speed, slip rate error, transmission input torque and friction clutch slip and computing a friction clutch control signal whereby the friction torque capacity of the clutch is controlled;

memory storage registers of the microprocessor being in communication with the base control unit for storing clutch engagement parameters during each control loop of the microprocessor;

the microprocessor including further an adaptative control unit for modifying the friction clutch engagement signal developed by the control unit during a current control loop of the microprocessor by adjusting clutch pressure values in accordance with control parameters stored in the memory storage registers during a preceding control loop thereby compensating driving friction clutch engagement;

the microprocessor adjusting clutch pressure values in accordance with control parameters stored in memory storage registers during the preceding control loop thereby compensating during friction clutch engagement for changes in system control parameters;

the transmission input torque calculated by the calculation unit being a feed-forward torque value, the calculation unit including a stored functional relationship between engine throttle position and engine torque and a torque multiplier value, the stored functional relationship being modified by the multiplier value to effect a torque product providing an early indication of friction clutch pressure requirements.

8. An electronic control system for controlling the engagement of a friction clutch of a multiple-ratio transmission in an automotive vehicle driveline during vehicle startup, the driveline having an output shaft and a throttle-controlled engine, the transmission having a torque converter with an impeller connected drivably to the engine and a turbine drivably connected to the friction clutch;

the control system comprising a microprocessor including a calculation unit, a base control unit, memory storage registers and an adaptive control unit;

a plurality of driveline sensors including an engine throttle position sensor, a transmission range selector position sensor, an output shaft speed sensor, a turbine speed sensor, and an engine speed sensor;

the microprocessor having an input signal conditioner with signal flow paths for receiving input and feedbacks signals from the sensors including an engine speed signal, a turbine speed signal and an output shaft speed signal;

the microprocessor further having a calculation unit for computing transmission input torque, friction clutch slip and vehicle speed based on the input and feedback signals, the microprocessor being characterized by sequential execution of software instructions in a continuous control loop in response to driveline input control data;

the calculation unit detecting commanded slip rate of the friction clutch and comparing it to the actual slip rate to detect an error; and

a base control unit of the microprocessor receiving computed vehicle speed, slip rate error, transmission input torque and friction clutch slip and computing a friction clutch control signal whereby the friction torque capacity of the clutch is controlled;

memory storage registers of the microprocessor being in communication with the base control unit for storing clutch engagement parameters during each control loop of the microprocessor;

the microprocessor including further an adaptative control unit for modifying the friction clutch engagement signal developed by the control unit during a current control loop of the microprocessor by adjusting clutch pressure values in accordance with control parameters stored in the memory storage registers during a preceding control loop thereby compensating driving friction clutch engagement;

the engine speed sensor, the turbine speed sensor and the output shaft speed sensor communicating with the calculation unit in a closed-loop fashion whereby the calculation unit determines in real time output signals indicating a vehicle speed signal, a clutch slip signal and commanded and actual friction clutch slip rate signals, output signals of the calculation unit being communicated to the base control unit;

the transmission input torque calculated by the calculation unit being a feed-forward torque value, the calculation unit including a stored functional relationship between engine throttle position and engine torque and a torque multiplier value, the stored functional relationship being modified by the multiplier value to effect a torque product providing an early indication of friction clutch pressure requirements.

9. A method for controlling engagement of a pressure-operated friction clutch of a multiple-ratio automatic transmission in a vehicle driveline having a throttle-controlled engine and an output shaft, the method comprising:

detecting driveline variables including throttle position, output shaft speed, engine speed, and transmission ratio;

calculating control parameters including friction clutch slip, transmission input torque, commanded clutch slip rate, actual clutch slip rate, slip rate error, and vehicle speed as a function of the driveline control variables;

determining desired clutch pressure as a function of current ratio, transmission input torque and vehicle speed;

executing a friction clutch engagement cycle by initiating an engagement start mode wherein clutch pressure is commanded to effect incipient clutch engagement;

initiating a torque transfer phase of the engagement cycle to control clutch pressure by increasing clutch pressure in the engagement start phase at a controlled rate; and

initiating a slip change phase of the engagement cycle by controlling clutch pressure in a closed-loop fashion thereby decreasing clutch slip to a desired value over a predetermined time;

the step of increasing clutch pressure at a controlled rate being achieved by increasing commanded clutch pressure as follows;

10. A method for controlling engagement of a pressure-operated friction clutch of a multiple-ratio automatic transmission in a vehicle driveline having a throttle-controlled engine and an output shaft, the method comprising:

detecting driveline variables including throttle position, output shaft speed, engine speed, and transmission ratio;

calculating control parameters including friction clutch slip, transmission input torque, commanded clutch slip rate, actual clutch slip rate, slip rate error, and vehicle speed as a function of the driveline control variables;

determining desired clutch pressure as a function of current ratio, transmission input torque and vehicle speed;

executing a friction clutch engagement cycle by initiating an engagement start mode wherein clutch pressure is commanded to effect incipient clutch engagement;

initiating a torque transfer phase of the engagement cycle to control clutch pressure by increasing clutch pressure in the engagement start phase at a controlled rate; and

initiating a slip change phase of the engagement cycle by controlling clutch pressure in a closed-loop fashion thereby decreasing clutch slip to a desired value over a predetermined time;

the slip change phase being followed during the engagement cycle by an engagement end phase whereby the commanded clutch pressure is increased nonlinearly until it reaches the commanded pressure thereby effecting full clutch engagement without an inertia torque disturbance during the engagement cycle; and

the closed-loop clutch control in the slip change phase of the engagement cycle being achieved by increasing commanded pressure for the clutch as follows;