System and method for controlling vehicle braking operation

• US 20010016795A1
• Filed: 02/22/2001
• Published: 08/23/2001
• Est. Priority Date: 11/13/1998
• Status: Active Grant

• Current Assignee: Cummins Incorporated
• Original Assignee: Cummins Incorporated
• Inventors: Bellinger, Steven M.
• Granted Patent: US 6,819,995 B2
• Time in Patent Office: Days
• US Class Current: 701/53
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 10/196 acting within the driveline, e.g. retarders
• CPC Class Codes: B60W 2720/106 Longitudinal acceleration
• CPC Class Codes: B60W 30/18136 Engine braking
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60Y 2400/435 Supercharger or turbochargers
• CPC Class Codes: F02B 37/00 Engines characterised by provision of pumps driven at least for part of the time by exhaust
• CPC Class Codes: F02D 17/023 the inactive cylinders acting as compressor other than for pumping air into the exhaust system
• CPC Class Codes: F02D 41/0007 for control of turbo-charged or super-charged engines control of the pumps per se F02B37/12
• CPC Class Codes: F02D 41/12 for deceleration F02D41/0005, F02D41/107 take precedence

Abstract

A system for controlling vehicle braking operation includes a mechanism for determining desired service brake force, a mechanism for determining vehicle deceleration, an electronically actuatable engine compression brake unit, an electronically controllable turbocharger boost pressure adjustment device and a transmission including a number of automatically selectable gear ratios, wherein each of these components are coupled to a control computer. The control computer is operable to activate the engine compression brakes whenever service brake action is detected, and to modulate the downshift engine speed points of the transmission as a function of the desired brake force. The boost pressure adjustment device and the engine compression brake may optionally be controlled to maintain a vehicle deceleration rate below a deceleration rate threshold. Alternatively, the downshift engine speed points may be controlled to maintain the vehicle deceleration rate below the deceleration rate threshold.

Claims

1. System for controlling vehicle braking operation, comprising:

an engine compression brake associated with an internal combustion engine for retarding engine operation;

a service brake associated with a vehicle carrying said engine;

means for determining activation of said service brake and producing a service brake signal corresponding thereto; and

a control computer responsive to said service brake signal to activate said engine compression brake.

2. The system of

claim 1

wherein said control computer is further operable to control and manage overall operation of said internal combustion engine.

3. The system of

claim 1

further including a transmission coupled to said internal combustion engine and including a number of automatically selectable gear ratios;

and wherein said control computer forms part of a transmission control module associated with said transmission, said control computer operable to control and manage overall operation of said transmission.

4. The system of

claim 3

further including:

an engine computer operable to control and manage overall operation of said internal combustion engine; and

means for transferring information between said control computer and said engine computer.

5. The system of

claim 1

wherein said engine compression brake includes a number of engine compression brake settings, each of said number of engine compression brake settings resulting in a different engine retarding torque;

and wherein said control computer is responsive to said service brake signal to activate said engine compression brake to provide for maximum engine retarding torque.

6. The system of

claim 5

further including:

means for determining a desired braking force of said service brake and producing a service brake force signal corresponding thereto; and

a transmission coupled to said internal combustion engine and including a number of automatically selectable gear ratios, each of said number of automatically selectable gear ratios having a downshift engine speed point corresponding thereto;

and wherein said control computer is operable to modify at least some of said number of downshift engine speed points as a function of said service brake force signal.

7. The system of

claim 6

wherein said control computer is configured to reduce engine speed values of at least some of said number of downshift engine speed points if said service brake force signal is below a force threshold, and to increase said engine speed values of at least some of said number of downshift engine speed points if said service brake force signal is above said force threshold.

8. The system of

claim 6

further including:

a turbocharger;

a wastegate valve operable to control turbocharger boost pressure; and

means for determining a vehicle deceleration rate;

wherein said control computer is operable to control said wastegate valve to maintain said vehicle deceleration rate below a deceleration threshold.

9. The system of

claim 8

wherein said control computer is configured to control said wastegate valve to maintain said vehicle deceleration below a first deceleration threshold if said service brake force signal is below a force threshold, and to maintain said vehicle deceleration below a second deceleration threshold different from said first deceleration threshold if said service brake force signal is above said force threshold.

10. The system of

claim 8

wherein said control computer is configured to control said engine compression brake to select an appropriate one of said number of engine compression brake settings as a function of said vehicle deceleration and said deceleration threshold.

11. The system of

claim 5

further including:

means for determining a desired braking force of said service brake and producing a service brake force signal corresponding thereto;

a transmission coupled to said internal combustion engine and including a number of automatically selectable gear ratios, each of said number of automatically selectable gear ratios having a downshift engine speed point corresponding thereto; and

means for determining vehicle deceleration;

and wherein said control computer is operable to modify said number of downshift engine speed points as a function of said vehicle deceleration.

12. The system of

claim 11

wherein said control computer is configured to modify said number of downshift engine speed points to maintain said vehicle deceleration below a first deceleration threshold if said service brake force signal is below a force threshold, and to maintain said vehicle deceleration below a second deceleration threshold different from said first deceleration threshold if said service brake force signal is above said force threshold.

13. The system of

claim 1

further including means for determining a desired braking force of said service brake and producing a service brake force signal corresponding thereto;

and wherein said engine compression brake includes a number of engine compression brake settings, each of said number of engine compression brake settings resulting in a different engine retarding torque;

and wherein said control computer is responsive to said service brake signal to select one of said engine compression brake settings as a function of said service brake force signal.

14. The system of 13 further including means for determining vehicle deceleration;

and wherein said control computer is operable to select said one of said engine compression brake settings further as a function of said vehicle deceleration.

15. The system of

claim 14

wherein said control computer is configured to select an appropriate one of said engine compression brake settings to maintain said vehicle deceleration below a first deceleration threshold if said service brake force signal is below a force threshold, and to select an appropriate one of said engine compression brake settings to maintain said vehicle deceleration below a second deceleration threshold different from said first deceleration threshold if said service brake force signal is above said force threshold.

16. The system of

claim 15

further including a transmission having a number of automatically selectable gear ratios, each of said number of automatically selectable gear ratios having a downshift engine speed point corresponding thereto;

and wherein said control computer is operable to modify at least some of said number of downshift engine speed points to achieve a target engine speed value following corresponding transmission downshifts if said service brake force signal is above said force threshold.

17. The system of

claim 16

wherein said control computer is configured to modify at least some of said number of downshift engine speed points to achieve said target engine speed value following corresponding transmission downshifts if said service brake force signal is below said force threshold.

18. The system of

claim 16

further including:

a turbocharger; and

a wastegate valve operable to control turbocharger boost pressure;

wherein said control computer is operable to control said wastegate valve to maintain said vehicle deceleration below said first deceleration threshold if said service brake force signal is below said force threshold, and to maintain said vehicle deceleration below said second deceleration threshold if said service brake force signal is above said force threshold.

19. The system of

claim 18

wherein said control computer is configured to control said engine compression brake to select an appropriate one of said number of engine compression brake settings as a function of said vehicle deceleration and said deceleration threshold.

20. System for controlling vehicle braking operation, comprising:

an engine compression brake associated with an internal combustion engine for retarding engine operation;

a service brake associated with a vehicle carrying said engine;

means for determining a desired braking force of said service brake and producing a service brake force signal corresponding thereto;

a transmission coupled to said engine and including a number of automatically selectable gear ratios, each of said number of automatically selectable gear ratios having an engine speed downshift point associated therewith; and

a control computer responsive to said service brake force signal to control said engine compression brake and said number of engine speed downshift points as a function thereof.

21. The system of

claim 20

further including:

a turbocharger; and

a wastegate valve operable to control turbocharger boost pressure;

and wherein said control computer is further responsive to said service brake force signal to control said wastegate valve as a function thereof.

22. A method of controlling vehicle brake operation, comprising the steps of:

monitoring a service brake associated with a vehicle carrying an internal combustion engine; and

activating an engine compression brake associated with said engine if said service brake is activated.

23. The method of

claim 22

further including the step of modifying engine speed downshift points of a number of automatically selectable gear ratios of a transmission coupled to said engine as a function of a desired braking force of said service brake.

24. The method of

claim 23

wherein the modifying step includes reducing said engine speed downshift points of said number of automatically selectable gear ratios if said desired braking force is below a force threshold, and increasing said engine speed downshift points of said number of automatically selectable gear ratios if said desired braking force is above said force threshold.

25. The method of

claim 24

further including the steps of:

determining a deceleration rate of said vehicle;

controlling either of a turbocharger wastegate valve and said engine compression brake to maintain said deceleration rate below a first deceleration threshold if said desired braking force is below said force threshold; and

controlling either of said turbocharger wastegate valve and said engine compression brake to maintain said deceleration rate below a second deceleration threshold different from said first deceleration threshold if said desired braking force is above said force threshold.

26. The method of

claim 23

further including the step of determining a deceleration rate of said vehicle;

and wherein the modifying step includes modifying said engine speed downshift points of said number of automatically selectable gear ratios to maintain said deceleration rate below a first deceleration threshold if said desired braking force is below a force threshold, and modifying said engine speed downshift points of said number of automatically selectable gear ratios to maintain said deceleration rate below a second deceleration threshold different from said first deceleration threshold if said desired braking force is above said force threshold.

27. The method of

claim 23

wherein the modifying step includes modifying said engine speed downshift points of said number of automatically selectable gear ratios to achieve a target engine speed value following transmission downshifts if said desired braking force is above a force threshold.

28. The method of

claim 27

further including the steps of:

determining a deceleration rate of said vehicle;

controlling either of a turbocharger wastegate valve and said engine compression brake to maintain said deceleration rate below a first deceleration threshold if said desired braking force is below said force threshold; and

controlling either of said turbocharger wastegate valve and said engine compression brake to maintain said deceleration rate below a second deceleration threshold different from said first deceleration threshold if said desired braking force is above said force threshold.