CONTROL OF VEHICLE DRIVELINE TORQUE

• US 20140067229A1
• Filed: 09/05/2012
• Published: 03/06/2014
• Est. Priority Date: 09/05/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Riedle, Bradley D., Probert, Brad W., Zhang, Jianping, Sovel, Kenneth E.
• Granted Patent: US 9,731,725 B2
• Time in Patent Office: Days
• US Class Current: 701/102
• CPC Class Codes: B60W 30/184 Preventing damage resulting from overload or excessive wear of the driveline
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart

Abstract

A method for controlling a vehicle driveline includes determining, for current vehicle operating conditions, an initial engine output torque, at which the driveline meets predetermined structural criteria, establishing a factor that varies with torque converter slip, determining an engine torque limit by multiplying the factor corresponding to a current torque converter slip by the initial engine output torque, and limiting torque produced by an engine connected to the driveline to the engine torque limit.

Claims

1. A method for controlling a vehicle driveline, comprising:

determining, for current vehicle operating conditions, an initial engine output torque, at which the driveline meets predetermined structural criteria;

establishing a factor that varies with torque converter slip;

determining an engine torque limit by multiplying the factor corresponding to a current torque converter slip by the initial engine output torque;

limiting torque produced by an engine connected to the driveline to the engine torque limit

2. The method of claim 1, wherein the factor is greater than unity when the current torque converter slip is relatively large and the factor is equal to unity when the current torque converter slip is relatively low.

3. The method of claim 1, wherein the step of determining an initial engine output torque further comprises:

establishing predetermined magnitude of engine output torque at which an ultimate torsional strength, a yield torsional strength, a fatigue torsional strength and a torsional endurance limit of components of the driveline are not exceed by engine torque produced by the engine.

4. The method of claim 1, wherein a magnitude of the engine torque limit is greater than a magnitude of the initial engine output torque.

15. The method of claim 1, wherein the engine torque limit is greater than a magnitude of the initial engine output torque.

5. A method for controlling a vehicle driveline, comprising:

identifying first operating conditions having a low frequency of occurrence wherein a relatively high engine torque transmitted through the driveline at low speed ratios is required;

identifying second operating conditions having a higher frequency of occurrence wherein a lower engine torque at higher speed ratios is required; and

allowing an engine to produce the relatively high engine torque only under the first operating conditions.

6. The method of claim 5 further comprising the relatively high engine torque produced under the first operating conditions to the lower engine torque under the second operating conditions as the speed ratio increases.

7. The method of claim 5 wherein torque converter slip is used to determine a limit of engine torque produced under the first operating conditions.

8. The method of claim 5 wherein torque converter slip is used to determine a limit of engine torque produced under the second operating conditions.

9. The method of claim 5 wherein the steps of identifying first and second operating conditions includes determining at least one of the vehicle mass, vehicle load, vehicle acceleration, gear ratio and torque converter speed ratio.

10. A vehicle driveline comprising:

an engine;

a torque converter connected to a crankshaft of the engine;

a transmission connected to a turbine of the torque converter

a differential connected to an output of the transmission;

axle shafts connecting the differential to wheels;

a controller including a processor configured to determine for current vehicle operating conditions an initial engine output torque at which the torque converter, transmission and differential meet predetermined structural criteria, and to determine an engine torque limit by multiplying a factor corresponding to a current torque converter slip by the initial engine output torque; and

an engine controller configured to limit torque produced by an engine connected to the driveline to the engine torque limit

11. The vehicle driveline of claim 10 wherein the processor is further configured to limit engine torque produced by the engine to a predetermined magnitude of engine output torque at which an ultimate torsional strength, a yield torsional strength, a fatigue torsional strength and a torsional endurance limit of components of the driveline are not exceeded.

12. A method for controlling a vehicle driveline, comprising:

limiting torque produced by an engine connected to the driveline to an engine torque limit based on an initial engine output torque for current vehicle operating conditions and a torque converter slip factor.

13. The method of claim 12, wherein the torque converter slip factor is greater than unity when the current torque converter slip is relatively large and the torque converter slip factor is equal to unity when the current torque converter slip is relatively low.

14. The method of claim 12, wherein the initial engine output torque is based on a predetermined magnitude of engine output torque at which an ultimate torsional strength, a yield torsional strength, a fatigue torsional strength and a torsional endurance limit of components of the driveline are not exceed by engine torque produced by the engine.