Powershift transmission system with torque-mapped shifts

• US 5,778,329 A
• Filed: 06/02/1995
• Issued: 07/07/1998
• Est. Priority Date: 12/30/1993
• Status: Expired due to Fees

• Current Assignee: AGCO Corporation, John Deere Electronic Solutions, Inc. (Deere & Company)
• Original Assignee: AGCO Corporation, Phoenix International Corp (Deere & Company)
• Inventors: Clausen, Scott A., Officer, Todd M., Kallis, Adrian G.
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/458,965
• Time in Patent Office: 1,131 Days
• Field of Search: 364/424.1, 364/431.07, 364/424.08, 477/32, 477/156, 477/161, 477/109, 477/102, 477/34, 477/120-129, 477/155, 477/166, 477/181, 477/98, 477/151-152, 477/33, 477/900-904, 477/130-133, 434/71, 192/3.55, 192/3.62, 192/3.63, 192/48.5, 192/85 A, 192/87.11, 60/602, 60/600, 60/611, 60/603, 60/608, 60/609, 60/606, 60/599, 123/559.3, 123/421, 123/564, 123/399, 123/502, 123/486, 123/559.1, 73/116, 73/117.3, 475/70, 475/130, 475/133
• US Class Current: 701/55
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: F16H 2059/088 Fast forward-reverse-sequence mode
• CPC Class Codes: F16H 2061/0096 using a parameter map
• CPC Class Codes: F16H 59/14 Inputs being a function of torque or torque demand
• CPC Class Codes: F16H 59/32 Supercharger pressure in internal combustion engines
• CPC Class Codes: F16H 59/36 Inputs being a function of speed
• CPC Class Codes: F16H 61/0246 characterised by initiating reverse gearshift
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: F16H 61/08 Timing control
• CPC Class Codes: F16H 61/70 specially adapted for change-speed gearing in group arrangement, i.e. with separate change-speed gear trains arranged in series, e.g. range or overdrive-type gearing arrangements

Abstract

A method for shifting a powershift transmission of a vehicle in accordance with the load being experienced by the engine as estimated from certain engine operating parameters. A turbocharger associated with an engine operating at a given engine speed generates a turbo boost pressure. The turbo boost pressure is monitored by a sensor and a turbo boost signal is generated therefrom. Similarly, the engine speed is monitored by a sensor and an engine speed signal is generated therefrom. The turbo boost and engine speed signals are used to estimate the engine load based on empirical data stored in the transmission controller'"'"'s memory, and a percentage load is computed therefrom. The percentage load is then used to generate an appropriate duty cycle and time value for a pulse-width-modulated shift signal which controls the modulation of an on-coming directional clutch into engagement at a desired rate of engagement dependent upon the load being experienced by the vehicle.

Claims

1. In an electronic controller of a powershift transmission system for an off-road vehicle having at least one proportionally-modulatable, directional clutch coupled to an engine having a turbocharger and operating at an engine speed, a method of controlling the powershift transmission system comprising the steps of:

monitoring a turbo boost pressure developed by the turbocharger and generating a turbo boost signal therefrom;

monitoring the engine speed and generating an engine speed signal therefrom;

estimating the load being experienced by the engine as a function of the turbo boost signal and the engine speed signal and producing an engine load value;

generating a shift profile signal based on the engine load value; and

communicating the shift profile signal to the directional clutch for controlling the engagement of the directional clutch to shift the powershift transmission.

2. The method of claim 1, wherein the step of determining an engine load comprises the steps of:

generating a data table representing the engine load as a function of a known engine speed and a known turbo boost pressure for a plurality of operating conditions;

comparing the turbo boost signal and the engine speed signal with the data table to determine the engine load value.

3. The method of claim 2, wherein the step of comparing the turbo boost signal and the engine speed signal further comprises linearly interpolating the engine load value from the data table, the turbo boost signal and the engine speed signal.

4. The method of claim 2, wherein the step of generating a data table comprises:

setting an operating condition for the engine, including a throttle condition, and an engine speed;

measuring measured values for the turbo boost pressure, the engine speed and the engine load to determine the known turbo boost pressure, the known engine speed and a known engine load for the operating condition; and

storing the known turbo boost pressure, the known engine speed and the known engine load as a data point in the data table to create a sparsely populated data table.

5. The method of claim 4, wherein the step of generating a data table further comprises the steps of approximating approximated values intermediate the measured values from at least two data points in the data table and storing the approximated values as a data point in the data table to create a more fully populated data table.

6. The method of claim 5, wherein the step of approximating approximated values comprises the step of performing a least squares regression for each unique set of four adjacent data points.

7. The method of claim 5, wherein the step of generating a data table further comprises the step of smoothing the data points of the more fully populated data table.

8. The method of claim 5, wherein the step of generating a data table further comprises the step of selecting data points from the fully populated data table at discrete engine speeds.

9. The method of claim 1, wherein the step of generating a shift profile signal further comprises the steps of:

determining a percentage load from the engine load value; and

generating a weighted shift profile signal based on the percentage load, a no-load shift profile and a full-load shift profile.

10. The method of claim 9 wherein the step of determining a percentage load comprises the steps of:

determining a full-load engine load value while the vehicle is being operated under wide-open-throttle and under a full-load condition; and

comparing the engine load value with the full-load engine value to determine a percentage load.

11. The method of claim 1, further comprising the steps of:

determining a turbo boost pressure calibration constant;

modifying the turbo boost signal in accordance with the calibration constant to produce a normalized turbo boost signal; and

utilizing the normalized turbo boost signal and the engine speed signal to determine the engine load value.

12. A method for shifting a powershift transmission in an off-road vehicle, the powershift transmission having at least one proportionally-modulatable, directional clutch coupled to an engine having a turbocharger and operating at an engine speed, the method comprising the steps of:

generating a data table representing a known engine load as a function of a known engine speed and a known turbo boost pressure for a plurality of operating conditions of the engine;

monitoring a turbo boost pressure developed by the turbocharger and generating a turbo boost signal therefrom;

monitoring the engine speed and generating an engine speed signal therefrom;

comparing the turbo boost signal and the engine speed signal with the data table to estimate the load being experienced by the engine and to produce an engine load value therefrom;

generating a shift profile signal based on the engine load value; and

modulating the directional clutch into engagement at a desired rate of engagement based on the shift profile signal to shift the transmission.

13. The method of claim 12, wherein the step of generating a data table comprises the step of empirically determining the known engine load as a function of the known turbo boost pressure and the known engine speed.

14. The method of claim 12, wherein the step of comparing the turbo boost signal and the engine speed signal further comprises the step of linearly interpolating the engine load value from the data table, the turbo boost signal and the engine speed signal.

15. The method of claim 12, wherein the step of generating a shift profile signal further comprises the steps of:

determining a percentage load from the engine load value; and

generating a weighted shift profile signal based on the percentage load, a no-load shift profile and a full-load shift profile.

16. The method of claim 15, wherein the step of determining a percentage load comprises the steps of:

determining a full-load engine load value while the vehicle is being operated under wide-open-throttle and under a full-load condition; and

comparing the engine load value with the full-load engine value to determine a percentage load.

17. A method of generating a data table having a known engine load, a known engine speed and a known turbo boost pressure for a plurality of operating conditions to be used in an electronic transmission controller for shifting a powershift transmission of an off-road vehicle having at least one proportionally-modulatable, directional clutch coupled to an engine having a turbocharger and operating at an engine speed, the method comprising the steps of:

setting an operating condition for the engine, including a throttle condition, a loading condition and an engine speed;

measuring measured values for the turbo boost pressure, the engine speed and the engine load to determine the known turbo boost pressure, the known engine speed and the known engine load for the operating condition; and

storing the known turbo boost pressure, the known engine speed and the known engine load as a data point in the data table to create a sparsely populated data table;

whereby an engine load value which estimates the load being experienced by the engine can be determined as a function of the known engine speed and the known turbo boost pressure.

18. The method of claim 17, further comprising the steps of approximating approximated values intermediate the measured values from at least two data points in the data table and storing the approximated values as a data point in the data table to create a more fully populated data table.

19. The method of claim 18, wherein the step of approximating approximated values comprises the step of performing a least squares regression for each unique set of four adjacent data points.

20. The method of claim 17, wherein the step of generating a data table further comprises the step of smoothing the data points of the more fully populated data table.

21. The method of claim 17, wherein the step of generating a data table further comprises the step of selecting data points from the fully populated data table at discrete engine speeds.

22. An electronic transmission controller for use in an off-road vehicle of the type having an engine including a turbo charger, a turbo boost pressure sensor and an engine speed sensor, and a powershift transmission system having at least one directional clutch which is proportionally modulatable in response to a shift profile signal for shifting the powershift transmission system, the electronic transmission controller comprising:

a turbo boost signal generator for generating a turbo boost signal from the turbo boost pressure sensor;

an engine speed signal generator for generating an engine speed signal from the engine speed sensor;

means for estimating the load being experienced by the engine as a function of the turbo boost signal and the engine speed signal and producing an engine load value; and

a shift profile signal generator for generating a shift profile signal from the engine load value,

whereby the shift profile signal proportionally modulates said at least on directional clutch for shifting the powershift transmission.

23. The electronic transmission controller of claim 22 further comprising a memory to store a data table representing a known engine load as a function of a known engine speed and a known turbo boost pressure for a plurality of operating conditions of the engine, whereby the engine load value is determined by comparing the turbo boost signal and the engine speed signal with the data table.

24. The electronic transmission controller of claim 23 wherein the electronic transmission controller is arranged to compute the engine load value from a linear interpolation of the data table, the turbo boost signal and the engine speed signal.

25. The electronic transmission controller of claim 22 further comprises a load signal generator for generating a percentage load from the engine load value, whereby a weighted shift profile signal is generated by the shift profile signal generator based on the percentage load, a no-load shift profile and a full-load shift profile.

26. A powershift transmission system for an off-road vehicle of the type having an engine including a turbo charger, a turbo boost pressure sensor and an engine speed sensor, the powershift transmission system comprising:

an electronic controller including a turbo boost signal generator for generating a turbo boost signal from the turbo boost pressure sensor, an engine speed signal generator for generating an engine speed signal from the engine speed sensor, an engine load value generator for generating an engine load value as a function of the turbo boost signal and the engine speed signal, and a shift profile signal generator for generating a shift profile signal from the engine load value; and

at least one directional clutch having a modulatable valve for proportionally modulating the at least one directional clutch into engagement at a desired rate of engagement in response to the shift profile signal to shift the powershift transmission system.

27. The powershift transmission system of claim 26 wherein the electronic controller further comprises a memory to store a data table representing a known engine load as a function of a known engine speed and a known turbo boost pressure for a plurality of operating conditions of the engine, whereby the engine load value is determined by comparing the turbo boost signal and the engine speed signal with the data table.

28. The powershift transmission system of claim 27 wherein the electronic transmission controller is arranged to compute the engine load value from a linear interpolation of the data table, the turbo boost signal and the engine speed signal.

29. The powershift transmission system of claim 26 wherein the electronic transmission controller further comprises a load signal generator for generating a percentage load from the engine load value, whereby a weighted shift profile signal is generated by the shift profile signal generator based on the percentage load, a no-load shift profile and a full-load shift profile.