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WO2002034562A1 - Back-up braking system and method for drive-by-wire vehicle - Google Patents

Back-up braking system and method for drive-by-wire vehicle Download PDF

Info

Publication number
WO2002034562A1
WO2002034562A1 PCT/NL2001/000775 NL0100775W WO0234562A1 WO 2002034562 A1 WO2002034562 A1 WO 2002034562A1 NL 0100775 W NL0100775 W NL 0100775W WO 0234562 A1 WO0234562 A1 WO 0234562A1
Authority
WO
WIPO (PCT)
Prior art keywords
engine
braking system
vehicle
speed
gear
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/NL2001/000775
Other languages
French (fr)
Inventor
Frank Wit
Eduardus Gerardus Maria Holweg
Bernardus Gerardus Van Leeuwen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SKF Engineering and Research Centre BV
Original Assignee
SKF Engineering and Research Centre BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SKF Engineering and Research Centre BV filed Critical SKF Engineering and Research Centre BV
Priority to AU2002214403A priority Critical patent/AU2002214403A1/en
Publication of WO2002034562A1 publication Critical patent/WO2002034562A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/06—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of combustion engines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/58—Combined or convertible systems
    • B60T13/585—Combined or convertible systems comprising friction brakes and retarders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
    • B60T17/18—Safety devices; Monitoring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/321—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration deceleration
    • B60T8/3255—Systems in which the braking action is dependent on brake pedal data
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/88—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means
    • B60T8/92—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means automatically taking corrective action
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/10—Conjoint control of vehicle sub-units of different type or different function including control of change-speed gearings
    • B60W10/11—Stepped gearings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/18—Conjoint control of vehicle sub-units of different type or different function including control of braking systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
    • B60W30/18—Propelling the vehicle
    • B60W30/18009—Propelling the vehicle related to particular drive situations
    • B60W30/18109—Braking
    • B60W30/18136—Engine braking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
    • B60W30/18—Propelling the vehicle
    • B60W30/1819—Propulsion control with control means using analogue circuits, relays or mechanical links
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K28/00—Safety devices for propulsion-unit control, specially adapted for, or arranged in, vehicles, e.g. preventing fuel supply or ignition in the event of potentially dangerous conditions
    • B60K28/10—Safety devices for propulsion-unit control, specially adapted for, or arranged in, vehicles, e.g. preventing fuel supply or ignition in the event of potentially dangerous conditions responsive to conditions relating to the vehicle 
    • B60K28/14—Safety devices for propulsion-unit control, specially adapted for, or arranged in, vehicles, e.g. preventing fuel supply or ignition in the event of potentially dangerous conditions responsive to conditions relating to the vehicle  responsive to accident or emergency, e.g. deceleration, tilt of vehicle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
    • B60W50/02—Ensuring safety in case of control system failures, e.g. by diagnosing, circumventing or fixing failures
    • B60W50/0205—Diagnosing or detecting failures; Failure detection models
    • B60W2050/021—Means for detecting failure or malfunction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2510/00—Input parameters relating to a particular sub-units
    • B60W2510/06—Combustion engines, Gas turbines
    • B60W2510/0638—Engine speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/21—Providing engine brake control

Definitions

  • the present system relates to a back-up braking system for use in a drive-by- wire vehicle, such as a passenger car. More specifically, the present invention relates to a back-up braking system for a vehicle, the vehicle being provided with an electronically controlled braking system and with a drive system comprising an engine having a throttle control for controlling the speed of the engine.
  • Such a system is known in a number of present and proposed vehicles having an electronically controlled braking system, such as the Electro Mechanical Brake Actuator produced by the applicant of the present invention.
  • a mechanical back-up braking system is provided, e.g. in the form of a mechanical parking brake.
  • the mechanical parking brake may be used to bring the vehicle to a controlled stop.
  • designers of fully electronic drive-by- wire vehicles are trying to find ways of removing the mechanical back-up braking system from the vehicle, as this saves cost, space and removes a mechanical system which itself may fail.
  • the electronically controlled braking system requires a redundant electrical system to enable a fail-safe operation of the vehicle.
  • the present invention seeks to provide an improved back-up system for braking in a drive-by- wire car which back-up system is able to reduce the speed of a vehicle in case of a failure of the electronically controlled braking system, without the use of a mechanical back-up braking system, such as a parking brake.
  • a back-up braking system is provided according to the preamble defined above, in which the back-up braking system is arranged to reduce the velocity of the vehicle using the throttle control for a predetermined braking action.
  • the internal friction of the engine may be used to slow down the vehicle. This allows to reduce the speed of a vehicle, or even bring the vehicle to a complete stop after failure of the electronically controlled braking system. This can be accomplished when the engine of the vehicle is either a combustion engine or an electrical engine. When the engine is an electrical engine, the vehicle may be brought to a complete stop by using the throttle control.
  • a drive train is connected to the engine, the drive train being provided with a clutch and gear control, and the clutch and gear control is used to shift to al lower gear when the engine speed is below a predetermined value.
  • the clutch and gear control is used to shift to al lower gear when the engine speed is below a predetermined value.
  • the engine is a combustion engine and the back-up braking system is arranged to halt the combustion of the engine at the lowest gear of the drive train, and at a predetermined engine speed.
  • This embodiment may also be used to provide an electronic parking brake for a drive-by- wire vehicle.
  • the vehicle is provided with two separate electrical power systems, the electronically controlled braking system being powered by a first electrical power system, and the throttle control being powered by a second electrical power system.
  • a fail-safe back-up braking system is also provided in the case of a failure of the first electrical power system supplying power to the electronically controlled braking system.
  • the drive When a drive train is connected to the engine, the drive may be provided with a clutch and gear control, the clutch and gear control being powered by the second electrical power system.
  • the throttle control and clutch and gear control it is possible to use the throttle control and clutch and gear control in case of failure of the first electrical power system.
  • the engine is a combustion engine under control of a combustion control being powered by the second electrical power system and the backup braking system is arranged to halt the combustion of the engine at the lowest gear of the drive train, and at a predetermined engine speed.
  • This embodiment may also be used to provide an electronic parking brake for a drive-by- wire vehicle having dual electrical power systems.
  • the first electrical power system may e.g. be a 42 volt power system and the second electrical power system may e.g. be a 12 volt power system.
  • the present invention relates to a method for reducing the velocity of a vehicle provided with an engine for driving the vehicle and with an electronically controlled braking system comprising the step of reducing the speed of the engine after failure of the electronically controlled braking system.
  • This method provides a fail-safe operation to reduce the speed of the vehicle, or to bring the vehicle to a complete stop, after failure of the electronically controlled braking system.
  • the vehicle is provided with a drive train connected to the engine, the drive train being provided with a clutch and gear control, the method comprising the further step of, at reduced speed of the engine, clutching and shifting to a lower gear.
  • This embodiment allows to effectively use the higher friction of the engine at higher engine speeds to reduce the speed of the vehicle or to bring the vehicle to a complete stop.
  • the method may in a further embodiment comprise the further step of, at the lowest gear of the drive train, and at a predetermined engine speed, halting the combustion of the engine. This may be accomplished by switching off the ignition in a gasoline engine, or by switching off the fuel supply.
  • the vehicle When the engine is at low speed, providing no further braking action, the vehicle may be brought to a complete stop using this embodiment. In the lowest gear of the drive train, the vehicle velocity will be close to zero, and the vehicle may be stopped by halting the combustion of the engine without danger for the occupants or without possible damage to the vehicle.
  • Fig. 1 shows a schematic diagram of a back-up braking system according to a first embodiment of the present invention
  • Fig. 2 shows a schematic diagram of a back-up braking system according to a second embodiment of the present invention.
  • FIG. 1 A very schematic diagram of a vehicle is presented in Fig. 1, showing only the elements of the vehicle which are important in understanding the present invention.
  • the vehicle is provided with an engine 5 for driving the vehicle.
  • the vehicle is equipped with wheels 7 which are driven by the engine 5.
  • the engine 5 is an electrical engine, the wheels may be driven directly.
  • the engine 5 is a combustion engine, the engine 5 drives the wheels 7 via a clutch and gearbox or an automatic gearbox, indicated by box 6 in Fig. 1, which enables the combustion engine 5 to be driven in its most effective speed range.
  • the vehicle in which the present invention is applied is equipped with an electronically controlled braking system 8 for performing a braking action on the wheels 7.
  • the electronically controlled braking system may e.g. be an electromechanical brake actuator as produced by the applicant.
  • the electronically controlled braking system 8 is controlled by brake control system 13 which monitors and controls the braking action of the electronically controlled braking system 8 and which supplies power to the braking system 8.
  • the engine 5 is controlled by an engine control system 11, which may comprise a throttle control for controlling the speed of the engine 5. Furthermore, when the engine 5 is a combustion engine, the engine control system 11 may further comprise a combustion system for controlling the fuel supply or ignition of the engine 5.
  • the gearbox and clutch or automatic gearbox 6 (in the case of a combustion engine 5) is controlled by a gear and clutch control system 12.
  • the gear and clutch control system 12 is preferably operating in a drive-by- wire mode, such that the selection of gear and the clutch can be controlled electronically.
  • a back-up braking system 10 is provided.
  • the back-up braking system 10 is connected to the engine control system 11, the gear and clutch control system 12 and the electronic brake control system 13.
  • the vehicle is equipped with a dual power supply system.
  • the electronic brake control system 13 (and via this the electronically controlled braking system 8) is supplied from a 42 volt power supply system 16.
  • a 42 volt power supply system is usually chosen as the electronically controlled braking system 8 has a higher than usual power requirement, which in a normal vehicle power supply system would lead to excessive high currents.
  • the other parts of the vehicle, especially the back-up braking system 10, engine control system 11 and gear and clutch control system 12, are supplied with power from the usual vehicle 12 volt power supply system 15.
  • the method of the present invention is preferably implemented in the back-up braking system 10.
  • the back-up braking system 10 is connected to the electronic brake control system 13 and monitors the proper functioning of the electronically controlled braking system 8 and the status of the 42 volt power supply system 16. Once a failure has been detected in either the 42 volt power supply system 16 or in the electronically controlled braking system 8, the back-up braking system 10 enables the speed of the vehicle to be reduced or the vehicle to be brought to a complete stop.
  • the engine 5 which is still mechanically coupled to the wheels 7, has an internal friction, which will reduce the speed of the veliicle.
  • the engine 5 is an electric engine directly driving the wheels 7, the speed of the vehicle can be reduced substantially and the vehicle can even be brought to a complete stop.
  • the engine 5 is a combustion engine, the braking action caused by the friction of the engine 5 will become very low below a certain engine speed.
  • the back-up braking system 10 supplies a signal to the gear and clutch control system 12 to shift to a lower gear. This causes the engine 5 to pick up speed again, enlarging the brake action again. This procedure is repeated until the lowest gear has been selected.
  • the back-up braking system 10 supplies a signal to the engine control system 11 to stop the engine 5 completely. As the engine 5 is still mechanically linked to the wheels 7, this will cause the vehicle to come to a complete stop. When the engine 5 is a diesel engine, this may be accomplished by cutting off the fuel supply to the engine 5. When the engine 5 is a gasoline engine, the engine 5 may be halted by interrupting the ignition of the engine 5.
  • the present invention thus provides an effective back-up braking system in case a failure occurs in the 42 volt power supply system 16, or in case a failure (electrical or mechanical) occurs in the electronically controlled braking system 8
  • the back-up braking system 10 may also be used as an electronic parking brake.
  • the user of the vehicle may use a switch (not shown) to indicate that the electronic parking brake should be applied.
  • the back-up braking system 10 will then send a signal to the gear and clutch control system to engage a gear (preferably the lowest gear) and a signal to the engine control system 11 to keep the engine 5 inoperative. This causes a mechanical link to be present between the engine 5 and the wheels 7, providing an effective parking brake function.
  • Fig. 2 shows an alternative embodiment of the present invention.
  • the vehicle is equipped with only a single power supply system 15, which also supplies power to the electronic brake control system 13 (and to the electronically controlled braking system 8).
  • the back-up braking system 10 will only be enabled when a failure is detected in the electronically controlled braking system 8, which may be a mechanical or electronic failure.

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Driving Devices And Active Controlling Of Vehicle (AREA)

Abstract

Back-up braking system (10) and method for reducing the velocity of a vehicle provided with an electronically controlled braking system (8, 13), and with a drive system comprising an engine (5) having a throttle control (11) for controlling the speed of the engine (5). The back-up braking system (10) is arranged to reduce the velocity of the vehicle using the throttle control (11) for a predetermined braking action. This may be accomplished by reducing the speed of the engine (5) after failure of the electronicallycontrolled braking system (8, 13) or by clutching and shifting toa lower gear at reduced speed of the engine. The vehicle may bestopped by halting the combustion of the engine (5) at the lowestgear of the drive train (6) and at a predetermined engine speed.

Description

Back-up braking system and method for drive-by- ire vehicle
The present system relates to a back-up braking system for use in a drive-by- wire vehicle, such as a passenger car. More specifically, the present invention relates to a back-up braking system for a vehicle, the vehicle being provided with an electronically controlled braking system and with a drive system comprising an engine having a throttle control for controlling the speed of the engine.
Such a system is known in a number of present and proposed vehicles having an electronically controlled braking system, such as the Electro Mechanical Brake Actuator produced by the applicant of the present invention.
In known systems usually a mechanical back-up braking system is provided, e.g. in the form of a mechanical parking brake. When a failure occurs of the electronically controlled braking system, the mechanical parking brake may be used to bring the vehicle to a controlled stop. However, designers of fully electronic drive-by- wire vehicles are trying to find ways of removing the mechanical back-up braking system from the vehicle, as this saves cost, space and removes a mechanical system which itself may fail. When no mechanical back-up braking system is present, the electronically controlled braking system requires a redundant electrical system to enable a fail-safe operation of the vehicle.
The present invention, therefore, seeks to provide an improved back-up system for braking in a drive-by- wire car which back-up system is able to reduce the speed of a vehicle in case of a failure of the electronically controlled braking system, without the use of a mechanical back-up braking system, such as a parking brake. According to the present invention, a back-up braking system is provided according to the preamble defined above, in which the back-up braking system is arranged to reduce the velocity of the vehicle using the throttle control for a predetermined braking action.
When the throttle control is used, the internal friction of the engine may be used to slow down the vehicle. This allows to reduce the speed of a vehicle, or even bring the vehicle to a complete stop after failure of the electronically controlled braking system. This can be accomplished when the engine of the vehicle is either a combustion engine or an electrical engine. When the engine is an electrical engine, the vehicle may be brought to a complete stop by using the throttle control.
In an embodiment of the back-up braking system according to the present invention, a drive train is connected to the engine, the drive train being provided with a clutch and gear control, and the clutch and gear control is used to shift to al lower gear when the engine speed is below a predetermined value. This enables to use the internal friction of the engine in an effective manner. As is known, the internal friction of a combustion engine is higher when the engine speed (or RPM) is higher. Shifting to a lower gear will cause the engine to run at a higher speed, resulting in a more effective braking action.
In a further embodiment, the engine is a combustion engine and the back-up braking system is arranged to halt the combustion of the engine at the lowest gear of the drive train, and at a predetermined engine speed. This allows the vehicle having a combustion engine to be brought to a complete stop, e.g. by disconnecting the ignition supply or the fuel supply to the engine. This embodiment may also be used to provide an electronic parking brake for a drive-by- wire vehicle.
In a further embodiment, the vehicle is provided with two separate electrical power systems, the electronically controlled braking system being powered by a first electrical power system, and the throttle control being powered by a second electrical power system. In this embodiment, a fail-safe back-up braking system is also provided in the case of a failure of the first electrical power system supplying power to the electronically controlled braking system.
When a drive train is connected to the engine, the drive may be provided with a clutch and gear control, the clutch and gear control being powered by the second electrical power system. In this embodiment it is possible to use the throttle control and clutch and gear control in case of failure of the first electrical power system.
In a further embodiment, the engine is a combustion engine under control of a combustion control being powered by the second electrical power system and the backup braking system is arranged to halt the combustion of the engine at the lowest gear of the drive train, and at a predetermined engine speed. This allows the vehicle with a combustion engine to come to a complete stop after failure of the first electrical power system. This embodiment may also be used to provide an electronic parking brake for a drive-by- wire vehicle having dual electrical power systems. The first electrical power system may e.g. be a 42 volt power system and the second electrical power system may e.g. be a 12 volt power system.
In a further aspect, the present invention relates to a method for reducing the velocity of a vehicle provided with an engine for driving the vehicle and with an electronically controlled braking system comprising the step of reducing the speed of the engine after failure of the electronically controlled braking system. This method provides a fail-safe operation to reduce the speed of the vehicle, or to bring the vehicle to a complete stop, after failure of the electronically controlled braking system.
In a further embodiment of the present method, the vehicle is provided with a drive train connected to the engine, the drive train being provided with a clutch and gear control, the method comprising the further step of, at reduced speed of the engine, clutching and shifting to a lower gear. This embodiment allows to effectively use the higher friction of the engine at higher engine speeds to reduce the speed of the vehicle or to bring the vehicle to a complete stop. When the engine is a combustion engine, the method may in a further embodiment comprise the further step of, at the lowest gear of the drive train, and at a predetermined engine speed, halting the combustion of the engine. This may be accomplished by switching off the ignition in a gasoline engine, or by switching off the fuel supply. When the engine is at low speed, providing no further braking action, the vehicle may be brought to a complete stop using this embodiment. In the lowest gear of the drive train, the vehicle velocity will be close to zero, and the vehicle may be stopped by halting the combustion of the engine without danger for the occupants or without possible damage to the vehicle.
The present invention will now be explained in further detail by using an exemplary embodiment of the present invention referring to the accompanying drawings, in which:
Fig. 1 shows a schematic diagram of a back-up braking system according to a first embodiment of the present invention; and
Fig. 2 shows a schematic diagram of a back-up braking system according to a second embodiment of the present invention.
A very schematic diagram of a vehicle is presented in Fig. 1, showing only the elements of the vehicle which are important in understanding the present invention. The vehicle is provided with an engine 5 for driving the vehicle. The vehicle is equipped with wheels 7 which are driven by the engine 5. In case the engine 5 is an electrical engine, the wheels may be driven directly. In case the engine 5 is a combustion engine, the engine 5 drives the wheels 7 via a clutch and gearbox or an automatic gearbox, indicated by box 6 in Fig. 1, which enables the combustion engine 5 to be driven in its most effective speed range.
The vehicle in which the present invention is applied is equipped with an electronically controlled braking system 8 for performing a braking action on the wheels 7. The electronically controlled braking system may e.g. be an electromechanical brake actuator as produced by the applicant. The electronically controlled braking system 8 is controlled by brake control system 13 which monitors and controls the braking action of the electronically controlled braking system 8 and which supplies power to the braking system 8.
The engine 5 is controlled by an engine control system 11, which may comprise a throttle control for controlling the speed of the engine 5. Furthermore, when the engine 5 is a combustion engine, the engine control system 11 may further comprise a combustion system for controlling the fuel supply or ignition of the engine 5.
The gearbox and clutch or automatic gearbox 6 (in the case of a combustion engine 5) is controlled by a gear and clutch control system 12. The gear and clutch control system 12 is preferably operating in a drive-by- wire mode, such that the selection of gear and the clutch can be controlled electronically.
According to the present invention, a back-up braking system 10 is provided. The back-up braking system 10 is connected to the engine control system 11, the gear and clutch control system 12 and the electronic brake control system 13.
In the embodiment shown in Fig. 1, the vehicle is equipped with a dual power supply system. The electronic brake control system 13 (and via this the electronically controlled braking system 8) is supplied from a 42 volt power supply system 16. A 42 volt power supply system is usually chosen as the electronically controlled braking system 8 has a higher than usual power requirement, which in a normal vehicle power supply system would lead to excessive high currents. The other parts of the vehicle, especially the back-up braking system 10, engine control system 11 and gear and clutch control system 12, are supplied with power from the usual vehicle 12 volt power supply system 15. The method of the present invention is preferably implemented in the back-up braking system 10. The back-up braking system 10 is connected to the electronic brake control system 13 and monitors the proper functioning of the electronically controlled braking system 8 and the status of the 42 volt power supply system 16. Once a failure has been detected in either the 42 volt power supply system 16 or in the electronically controlled braking system 8, the back-up braking system 10 enables the speed of the vehicle to be reduced or the vehicle to be brought to a complete stop.
This is accomplished by supplying a control signal to the engine control system 11 to reduce the speed of the engine 5. The engine 5, which is still mechanically coupled to the wheels 7, has an internal friction, which will reduce the speed of the veliicle. When the engine 5 is an electric engine directly driving the wheels 7, the speed of the vehicle can be reduced substantially and the vehicle can even be brought to a complete stop. When the engine 5 is a combustion engine, the braking action caused by the friction of the engine 5 will become very low below a certain engine speed. Once the speed of the engine 5 is below a predetermined value (at which the braking action caused by the friction of the engine 5 becomes low), the back-up braking system 10 supplies a signal to the gear and clutch control system 12 to shift to a lower gear. This causes the engine 5 to pick up speed again, enlarging the brake action again. This procedure is repeated until the lowest gear has been selected.
Once the vehicle is at a very low speed, the back-up braking system 10 supplies a signal to the engine control system 11 to stop the engine 5 completely. As the engine 5 is still mechanically linked to the wheels 7, this will cause the vehicle to come to a complete stop. When the engine 5 is a diesel engine, this may be accomplished by cutting off the fuel supply to the engine 5. When the engine 5 is a gasoline engine, the engine 5 may be halted by interrupting the ignition of the engine 5.
The present invention thus provides an effective back-up braking system in case a failure occurs in the 42 volt power supply system 16, or in case a failure (electrical or mechanical) occurs in the electronically controlled braking system 8
The back-up braking system 10 may also be used as an electronic parking brake. When the vehicle is being brought to a complete stop, the user of the vehicle may use a switch (not shown) to indicate that the electronic parking brake should be applied. The back-up braking system 10 will then send a signal to the gear and clutch control system to engage a gear (preferably the lowest gear) and a signal to the engine control system 11 to keep the engine 5 inoperative. This causes a mechanical link to be present between the engine 5 and the wheels 7, providing an effective parking brake function. Fig. 2 shows an alternative embodiment of the present invention. In this embodiment, the vehicle is equipped with only a single power supply system 15, which also supplies power to the electronic brake control system 13 (and to the electronically controlled braking system 8). In this case, the back-up braking system 10 will only be enabled when a failure is detected in the electronically controlled braking system 8, which may be a mechanical or electronic failure.

Claims

1. Back-up braking system (10) for a vehicle, the vehicle being provided with an electronically controlled braking system (13), and with a drive system comprising an engine (5) having a throttle control (11) for controlling the speed of the engine (5), characterised in that the back-up braking system (10) is arranged to reduce the velocity of the vehicle using the throttle control (11) for a predetermined braking action.
2. Back-up braking system according to claim 1, in which a drive train (6) is connected to the engine (5), the drive train (6) being provided with a clutch and gear control (12), the back-up braking system (10) being arranged to use the clutch and gear control (12) to shift to a lower gear when the engine speed is below a predetermined value.
3. Back-up braking system according to claim 1 or 2, in which the engine (5) is a combustion engine and the back-up braking system (10) is arranged to halt the combustion of the engine (5) at the lowest gear of the drive train (6), and at a predetermined engine speed.
4. Back-up braking system according to claim 1, in which the vehicle is provided with two separate electrical power systems (15, 16), the electronically controlled braking system (13) being powered by a first electrical power system (16), and the throttle control (11) being powered by a second electrical power system (15).
5. Back-up braking system according to claim 4, in which a drive train (6) is connected to the engine (5), the drive train (6) being provided with a clutch and gear control (12), the clutch and gear control (12) being used to shift to a lower gear when the engine speed is below a predetermined value, the clutch and gear control (12) being powered by the second electrical power system (15).
6. Back-up braking system according to claim 4 or 5, in which the engine (5) is a combustion engine under control of a combustion control (11) being powered by the second electrical power system (15) and the back-up braking system (10) is arranged to halt the combustion of the engine (5) at the lowest gear of the drive train (6), and at a predetermined engine speed.
7. Back-up braking system according to claim 4, 5 or 6, in which the first electrical power system (16) is a 42 volt power system.
8. Back-up braking system according to claim 4, 5, 6 or 1, in which the second electrical power system (15) is a 12 volt power system
9. Method for reducing the velocity of a vehicle provided with an engine (5) for driving the vehicle and with an electronically controlled braking system (8, 13) comprising the step of
-reducing the speed of the engine (5) after failure of the electronically controlled braking system (8, 13).
10. Method according to claim 9, in which the vehicle is provided with a drive train (6) connected to the engine (5), the drive train (6) being provided with a clutch and gear control (12), the method comprising the further step of
- at reduced speed of the engine (5), clutching and shifting to a lower gear.
11. Method according to claim 9 or 10, in which the engine (5) is a combustion engine and the method comprises the further step of at the lowest gear of the drive train (6), and at a predetermined engine speed, halting the combustion of the engine (5). # ****** *
PCT/NL2001/000775 2000-10-23 2001-10-23 Back-up braking system and method for drive-by-wire vehicle Ceased WO2002034562A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002214403A AU2002214403A1 (en) 2000-10-23 2001-10-23 Back-up braking system and method for drive-by-wire vehicle

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1016457A NL1016457C2 (en) 2000-10-23 2000-10-23 Spare braking system and method for electronically controlled (drive-by-wire) vehicle.
NL1016457 2000-10-23

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FR2843918A1 (en) * 2002-08-27 2004-03-05 Renault Sa METHOD FOR MANAGING THE SPEED OF A VEHICLE, WITH AN EMERGENCY OPERATING MODE
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