System and method for controlling vehicle braking operation

• US 6,819,995 B2
• Filed: 02/22/2001
• Issued: 11/16/2004
• Est. Priority Date: 11/13/1998
• Status: Expired due to Term

• Current Assignee: Cummins Incorporated
• Original Assignee: Cummins Incorporated
• Inventors: Bellinger, Steven M.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): To, Tuan C
• Application Number:
  US09/790,927
• Publication Number:
  US 20010016795A1
• Time in Patent Office: 1,363 Days
• Field of Search: 477/115, 477/121, 477/78, 477/108, 477/98, 477/124, 477/118, 477/120, 477/27, 477/32, 477/94, 477/97, 477/901, 477/86, 477/92, 477/107, 477/33, 701/70, 701/53, 701/54, 701/61, 701/83, 701/86, 701/93, 701/94, 701/95, 701/36, 701/51, 701/336.R, 731/16, 731/181, 123/357, 123/182.1, 123/321, 123/322
• 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, the system comprising:

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

an engine compression brake for retarding operation of said engine;

means for producing a service brake activation signal when said service brake is activated;

means for determining a deceleration rate of said vehicle; and

a control computer responsive to said service brake activation signal to control a retarding force of said engine compression brake as a function of said deceleration rate of said vehicle.

2. The system of claim 1 further including:

a turbocharger responsive to engine exhaust gas flow to supply boost air pressure to said engine; and

a wastegate valve coupled to said turbocharger for controllably diverting engine exhaust gas away from said turbocharger;

wherein said control computer is operable to control said wastegate valve as a function of said deceleration rate of said vehicle to control said boost air pressure and thereby control an operational effectiveness of said engine compression brake.

3. The system of claim 1 further including a transmission coupled to said engine and including a number of automatically selectable gear ratios with adjacent ones of said gear ratios having associated downshift engine speed points corresponding to engine speeds at which said transmission downshifts between said adjacent ones of said gear ratios;

wherein said control computer is operable to modify one or more of said engine speed shift points such that rotational speed of said engine is maintained in an engine speed range that maximizes operational effectiveness of said engine compression brake.

4. The system of claim 3 wherein said control computer is operable to modify said one or more of said engine speed shift points as a function of engine speed step change values corresponding to engine speed step changes between adjacent ones of said automatically selectable gear ratios, and of a governed engine speed value corresponding to a predefined engine speed, such that resulting rotational speed of said engine following transmission downshifts is maintained near said governed engine speed value.

5. The system of claim 4 further including:

a turbocharger responsive to engine exhaust gas flow to supply boost air pressure to said engine; and

a wastegate valve coupled to said turbocharger for controllably diverting engine exhaust gas away from said turbocharger;

wherein said control computer is operable to control said wastegate valve as a function of said deceleration rate of said vehicle to control said boost air pressure and thereby control an operational effectiveness of said engine compression brake.

6. The system of claim 1 further including means for determining a force applied to said service brake and producing a service brake force signal corresponding thereto;

wherein said control computer is responsive to said service brake force signal to determine a deceleration rate threshold as a function thereof, said control computer controlling said retarding force of said engine compression brake further as a function of said deceleration rate threshold value to maintain said deceleration rate of said vehicle below said deceleration rate threshold.

7. The system of claim 6 further including:

a turbocharger responsive to engine exhaust gas flow to supply boost air pressure to said engine; and

a wastegate valve coupled to said turbocharger for controllably diverting engine exhaust gas away from said turbocharger;

wherein said control computer is operable to control said wastegate valve as a function of said deceleration rate of said vehicle to control said boost air pressure and thereby control an operational effectiveness of said engine compression brake in a manner that maintains said deceleration rate of said vehicle below said deceleration rate threshold.

8. The system of claim 6 further including a transmission coupled to said engine and including a number of automatically selectable gear ratios with adjacent ones of said gear ratios having associated downshift engine speed points corresponding to engine speeds at which said transmission downshifts between said adjacent ones of said gear ratios;

wherein said control computer is operable to modify one or more of said engine speed shift points such that rotational speed of said engine is maintained in an engine speed range that maximizes operational effectiveness of said engine compression brake.

9. The system of claim 8 wherein said control computer is operable to modify said one or more of said engine speed shift points as a function of engine speed step change values corresponding to engine speed step changes between adjacent ones of said automatically selectable gear ratios, and of a governed engine speed value corresponding to a predefined engine speed, such that resulting rotational speed of said engine following transmission downshift is maintained near said governed engine speed value.

10. The system of claim 9 further including:

a turbocharger responsive to engine exhaust gas flow to supply boost air pressure to said engine; and

a wastegate valve coupled to said turbocharger for controllably diverting engine exhaust gas away from said turbocharger;

wherein said control computer is operable to control said wastegate valve as a function of said deceleration rate of said vehicle to control said boost air pressure and thereby control an operational effectiveness of said engine compression brake in a manner that maintains said deceleration rate of said vehicle below said deceleration rate threshold.

11. The system of claim 1 wherein said control computer is an engine control computer operable to control and manage overall operation of said engine.

12. The system of claim 1 further including a transmission coupled to said engine and including a number of selectable gear ratios;

wherein said control computer is a transmission control computer operable to control and manage overall operation of said transmission.

13. The system of claim 12 further including:

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

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

14. System for controlling vehicle braking operation, the system comprising:

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

an engine compression brake for retarding operation of said engine;

means for determining a force applied to 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 with adjacent ones of said gear ratios having associated downshift engine speed points corresponding to engine speeds at which said transmission downshifts between said adjacent ones of said gear ratios; and

a control computer responsive to said service brake force signal to activate said engine compression brake, and to modify one or more of said number of engine speed downshift points as a function of said service brake force signal, if said service brake force signal indicates that said service brakes have been activated.

15. The system of claim 14 wherein said engine compression brake includes a number of engine compression brake settings each corresponding to a different engine retarding force;

and wherein said control computer is operable to activate said engine compression brake such that said engine compression brake provides maximum engine retarding force.

16. The system of claim 14 further including:

a turbocharger responsive to engine exhaust gas flow to supply boost air pressure to said engine;

a wastegate valve coupled to said turbocharger for controllably diverting engine exhaust gas away from said turbocharger; and

means for determining a deceleration rate of said vehicle;

wherein said control computer is responsive to said service brake force signal to determine a deceleration rate threshold as a function thereof, said control computer controlling said wastegate valve as a function of said deceleration rate of said vehicle to control said boost air pressure and thereby control an operational effectiveness of said engine compression brake in a manner that maintains said deceleration rate of said vehicle below said deceleration rate threshold.

17. The system of claim 16 wherein said control computer is operable to further control a retarding force of said engine compression brake as a function of said deceleration rate of said vehicle to maintain said deceleration rate of said vehicle below said deceleration rate threshold.

18. The system of claim 14 further including means for determining a deceleration rate of said vehicle;

wherein said control computer is responsive to said service brake force signal to determine a deceleration rate threshold as a function thereof, said control computer controlling a retarding force of said engine compression brake as a function of said deceleration rate of said vehicle to maintain said deceleration rate of said vehicle below said deceleration rate threshold.

19. The system of claim 14 wherein said control computer is an engine control computer operable to control and manage overall operation of said engine.

20. The system of claim 14 further including a transmission coupled to said engine and including a number of selectable gear ratios;

wherein said control computer is a transmission control computer operable to control and manage overall operation of said transmission.

21. The system of claim 20 further including:

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

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

22. System for controlling vehicle braking operation, the system comprising:

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

an engine compression brake for retarding operation of said engine;

means for producing a service brake activation signal when said service brake is activated;

means for determining a deceleration rate of said vehicle;

a transmission coupled to said engine and including a number of automatically selectable gear ratios with adjacent ones of said gear ratios having associated downshift engine speed points corresponding to engine speeds at which said transmission downshifts between said adjacent ones of said gear ratios; and

a control computer responsive to said service brake activation signal to activate said engine compression brake and to modify one or more of said number of engine speed downshift points as a function of said deceleration rate of said vertical.

23. The system of claim 22 further including means for determining a force applied to said service brake and producing a service brake force signal corresponding thereto;

wherein said control computer is responsive to said service brake force signal to determine a deceleration rate threshold as a function thereof, said control computer modifying said one or more of said number of engine speed downshift points further as a function of said deceleration rate threshold value to maintain said deceleration rate of said vehicle below said deceleration rate threshold.

24. The system of claim 22 wherein said engine compression brake includes a number of engine compression brake settings each corresponding to a different engine retarding force;

and wherein said control computer is operable to activate said engine compression brake such that said engine compression brake provides maximum engine retarding force.

25. The system of claim 22 wherein said control computer is an engine control computer operable to control and manage overall operation of said engine.

26. The system of claim 22 further including a transmission coupled to said engine and including a number of selectable gear ratios;

wherein said control computer is a transmission control computer operable to control and manage overall operation of said transmission.

27. The system of claim 26 further including:

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

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