SE1950479A1 - Method for controlling a braking system, control device, computer program, computer- readable medium and vehicle - Google Patents

Method for controlling a braking system, control device, computer program, computer- readable medium and vehicle

Info

Publication number
SE1950479A1
SE1950479A1 SE1950479A SE1950479A SE1950479A1 SE 1950479 A1 SE1950479 A1 SE 1950479A1 SE 1950479 A SE1950479 A SE 1950479A SE 1950479 A SE1950479 A SE 1950479A SE 1950479 A1 SE1950479 A1 SE 1950479A1
Authority
SE
Sweden
Prior art keywords
braking
medium
auxiliary brake
temperature
torque
Prior art date
Application number
SE1950479A
Other languages
Swedish (sv)
Other versions
SE543381C2 (en
Inventor
Alexander Stamp
Andreas Szilassy
Christian Wessel
Original Assignee
Scania Cv Ab
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 Scania Cv Ab filed Critical Scania Cv Ab
Priority to SE1950479A priority Critical patent/SE543381C2/en
Priority to DE102020000876.3A priority patent/DE102020000876A1/en
Publication of SE1950479A1 publication Critical patent/SE1950479A1/en
Publication of SE543381C2 publication Critical patent/SE543381C2/en

Links

Classifications

    • 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
    • B60T10/00—Control or regulation for continuous braking making use of fluid or powdered medium, e.g. for use when descending a long slope
    • B60T10/02—Control or regulation for continuous braking making use of fluid or powdered medium, e.g. for use when descending a long slope with hydrodynamic brake
    • 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
    • B60W10/02—Conjoint control of vehicle sub-units of different type or different function including control of driveline clutches
    • 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
    • B60T1/00—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles
    • B60T1/02—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels
    • B60T1/08—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels using fluid or powdered medium
    • B60T1/087—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels using fluid or powdered medium in hydrodynamic, i.e. non-positive displacement, 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
    • 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
    • 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
    • B60T13/66—Electrical control in fluid-pressure brake systems
    • B60T13/662—Electrical control in fluid-pressure brake systems characterised by specified functions of the control system components
    • 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
    • B60T17/22—Devices for monitoring or checking brake systems; Signal devices
    • 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
    • B60T5/00—Vehicle modifications to facilitate cooling of brakes
    • 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
    • B60W10/184—Conjoint control of vehicle sub-units of different type or different function including control of braking systems with wheel brakes
    • 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
    • B60W10/196—Conjoint control of vehicle sub-units of different type or different function including control of braking systems acting within the driveline, e.g. retarders
    • 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
    • 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
    • B60W30/184—Preventing damage resulting from overload or excessive wear of the driveline
    • B60W30/1843—Overheating of driveline components
    • 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
    • B60W50/0097—Predicting future conditions
    • 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
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D57/00—Liquid-resistance brakes; Brakes using the internal friction of fluids or fluid-like media, e.g. powders
    • F16D57/04—Liquid-resistance brakes; Brakes using the internal friction of fluids or fluid-like media, e.g. powders with blades causing a directed flow, e.g. Föttinger type
    • 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
    • B60T1/00—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles
    • B60T1/02—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels
    • B60T1/08—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels using fluid or powdered medium
    • 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
    • B60T2201/00—Particular use of vehicle brake systems; Special systems using also the brakes; Special software modules within the brake system controller
    • B60T2201/04—Hill descent control
    • 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
    • B60W2510/18—Braking system
    • B60W2510/184—Brake temperature, e.g. of fluid, pads or discs
    • 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
    • B60W2552/00—Input parameters relating to infrastructure
    • B60W2552/15—Road slope, i.e. the inclination of a road segment in the longitudinal direction
    • 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
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D66/00—Arrangements for monitoring working conditions, e.g. wear, temperature
    • F16D2066/001—Temperature

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transportation (AREA)
  • Automation & Control Theory (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Regulating Braking Force (AREA)

Abstract

A control device (100) and a method for controlling a braking system (30) for a vehicle (1) is provided. The braking system comprises a first auxiliary brake (10) operable by a braking medium, a cooling system (8) configured to cool the first auxiliary brake, and one or more additional brake means (7, 25). The method comprises predicting a future temperature (Tp) of the braking medium, reducing a currently requested braking torque from the first auxiliary brake if the predicted future temperature of the braking medium is above a maximum temperature (Tmax) of the braking medium, and controlling the one or more additional brake means of the braking system so as to compensate for a loss of braking torque from the first auxiliary brake resulting from the reduction of the initially requested braking torque from the first auxiliary brake. A computer program, a computer-readable medium are also disclosed, as well as a vehicle comprising a braking system.

Description

METHOD FOR CONTROLLING A BRAKING SYSTEM, CONTROL DEVICE, COMPUTER PROGRAM,COMPUTER- READABLE MEDIUM AND VEHICLE TECHNICAL FIELD The present disclosure relates in general to a method for controlling a braking system for a vehicleand a control device configured to control a braking system of a vehicle. The present disclosurefurther relates in general to a computer program and a computer-readable medium. Moreover, the present disclosure relates in general to a vehicle comprising a braking system.
BACKGROUND ln heavy vehicles, an automatic braking process may be used that provide the vehicle with a desireddownhill speed by activation of one or more auxiliary brakes. A control arrangement may be adaptedto estimate the braking effect required for e.g. maintaining the speed which the vehicle wastravelling downhill at the time of initiating the process, and to activate one or more auxiliary brakeswith the corresponding braking effect. The automatic braking process may also be used in situationsother than downhill travel, such as to achieve a faster or smoother braking effect, or for the purposeof reducing the usage of the service brakes to thereby avoid unnecessary wear thereof. These other situations are however not associated with a risk of an undesirable acceleration of the vehicle.
An auxiliary brake may for example be a retarder, an exhaust brake, an engine brake, a compressionbrake or the like. A retarder comprises a stator, a rotor and a braking medium (such as oil) that flowsat high velocity between the stator and the rotor when the retarder is activated. During the brakingprocess, the kinetic energy of the braking medium converts to thermal energy. The cooling systemconfigured to cool the combustion engine may be used to also cool the braking medium of retarder.However, the cooling system of the combustion engine is primarily dimensioned for cooling thecombustion engine, and cooling the braking medium of the retarder may sometime require a greatercooling effect than that cooling the vehicle's engine. lt is therefore not unusual during for example asteep downhill run that the temperature of the braking medium of the retarder may rise to an unacceptable level.
Current systems are often based on reducing the braking torque in the auxiliary brake when a criticaltemperature of the coolant is reached. Such a reduction of the torque of the auxiliary brake often has to be compensated by activation of other auxiliary brakes or by usage of the service brakes to avoid undesirable acceleration of the vehicle, for example in a downhill slope. However, the activation ofother auxiliary brakes takes some time and this in turn may allow the vehicle to accelerate, which inturn increases the load on the activated other auxiliary brakes when they become activated due tothe increased speed of the vehicle. Moreover, if such additional auxiliary brakes are alreadymaximally activated, the service brakes will have to be relied on for keeping an acceptable speed of the vehicle, which in turn increases the wear on the service brakes.
WO 2005/080166 discloses an example of a method and arrangement for braking a vehicle wherein asupplementary brake may be activated only with the braking effect possible to maintain throughouta downhill run without overloading the cooling system of the supplementary brake. The driver maythen decide to either accept a higher vehicle speed than desired, or temporarily activate the vehicle's wheel brakes to maintain the desired vehicle speed during the downhill run.
WO 2008/091193 discloses an example of a method for controlling cooling of an auxiliary brake of avehicle, such as a retarder. A cooling fan is arranged to cool a coolant, which in turn is arranged tocool the braking medium of the auxiliary brake. According to this method, the cooling fan may beactivated automatically provided that a downhill slope steepness is within a predetermined interval.The method comprises pre-cooling the auxiliary brake and pre-loading the cooling system such thatthe cooling system is able to cool the auxiliary brake when the need for cooling the auxiliary brake is increased.
SUMMARY The object of the present invention is to provide an efficient control of a braking system of a vehicle,so as to obtain a desired braking effect when needed, with reduced risk for wear or damage of the constituent components of the braking system.
The object is achieved by the subject-matter of each one of the appended independent claims. ln accordance with the present disclosure, a method for controlling a braking system for a vehicle isprovided. The braking system comprises a first auxiliary brake operable by a braking medium, acooling system configured to cool the first auxiliary brake, and one or more additional brake means.The method comprises a step (a) of, based on a current temperature of the braking medium and a current requested braking torque of the first auxiliary brake, predicting a future temperature of the braking medium. The method further comprises a step (b) of, if the predicted future temperature ofthe braking medium is above a predetermined maximum temperature of the braking medium,reducing the current requested braking torque of the first auxiliary brake to an adjusted brakingtorque to be demanded from the first auxiliary brake. The method may also comprise a step ofcontrolling the first auxiliary brake based on the obtained adjusted braking torque to be demandedfrom the first auxiliary brake. Alternatively, the method may comprise reiterating steps of themethod until an appropriate adjusted braking torque to be demanded from the first auxiliary brake,which results in the predicted future temperature of the braking medium being equal to or lowerthan the predetermined maximum temperature of the braking medium, has been obtained andthereafter controlling the first auxiliary brake on the basis of the obtained appropriate adjustedbraking torque to be demanded from the first auxiliary brake. The method further comprises a step(c) of controlling the one or more additional brake means to compensate for the difference inbraking torque between said current requested braking torque and the adjusted braking torque (orappropriate adjusted braking torque) to be demanded from the first auxiliary brake. The method is performed by a control device.
By means of the present method, the risk of the first auxiliary brake becoming overheated may besignificantly reduced, or even avoided. The reason for this is that the first auxiliary brake may becontrolled based on an adjusted braking torque lower than the initially requested braking torquewhich over time could risk resulting in the temperature of the braking medium becoming higher that the predetermined maximum temperature. ln view of the fact that the present method considers a predicted future temperature for the controlof the braking system, the activation time of other auxiliary brakes than the first auxiliary brake maybe initiated at an early point in time, if needed. This is turn results in that a compensation ofpotential loss of desired braking torque from the first auxiliary brake may be achieved quicker.Thereby, the risk of an undesirable acceleration of the vehicle may be minimized. Furthermore, wearof the one or more additional brake means of the braking system may be minimized due to theactivation thereof at a lower vehicle speed, the lower vehicle speed resulting from the minimization of the undesired acceleration of the vehicle.
Furthermore, the method according to the present disclosure also has the advantage of not having torely on information (for example by a positioning system and map data) regarding a present or upcoming inclination. Such data may not always be known, for example, when the vehicle is travelling off road. Thus, the method for controlling a braking system in accordance with the present disclosure may be used for a broader range of driving situations of the vehicle.
The step of predicting the future temperature of the braking medium may comprise also taking intoaccount the current ambient temperature and/or the current cooling capacity of the cooling system.Thereby, the accuracy of the predicted future temperature may be increased, which in turn improves the control of the braking system so as to achieve the above mentioned object.
Step (b) may for example comprise reducing the current requested braking torque by apredetermined fixed amount of torque or a percentage of the current requested braking torque.Thereby, an easy control of the braking system may be achieved without the need of knowing to which extent the first auxiliary brake may be used to avoid overheating.
The method may further comprise, after step (b), repeating step (a) with usage of the adjustedbraking torque to be demanded from the first auxiliary brake as the current requested brakingtorque of the first auxiliary brake in step (a), and iterating steps (a) and (b) until an appropriateadjusted braking torque to be demanded from the first auxiliary brake which results in a predictedfuture temperature of the braking medium being equal to or lower than the predeterminedmaximum temperature of the braking medium has been obtained. Thereby, the first auxiliary brakemay for example be controlled directly based on an appropriate adjusted braking torque to bedemanded which avoids the risk of overheating of the first auxiliary brake. Thus, the control of the braking system may be further improved.
The method may further comprise, after step (a), a step (al) of, if the predicted future temperatureof the braking medium is above the predetermined maximum temperature of the braking medium,increasing the cooling of the auxiliary brake by increasing the cooling capacity of the cooling system,if not already at maximum cooling capacity. Moreover, the method may in such a case comprise astep (a2) of, before step (b), repeating step (a) taking into account the increased cooling capacity ofthe cooling system. Thereby, it may for example be avoided to control the first auxiliary brake to alower braking demand than desired if an increase of the temperature of the braking medium toabove the predetermined maximum temperature can be avoided already by usage of the coolingsystem. This in turn may avoid an unnecessary usage of the one or more additional brake means asno compensation for a loss of braking torque from the first auxiliary brake will occur. Moreover, the reduction of braking torque from the first auxiliary brake may be lower compared to if the cooling system is not at its maximum cooling capacity, even in cases where the predicted future temperature of the braking medium is above the predetermined maximum temperature thereof.
The method may further comprise determining the current temperature of the braking medium bymeasuring the temperature of the braking medium. Alternatively, the method may comprisedetermining the current temperature of the braking medium by measuring the temperature of acirculating cooling medium in the cooling system. Alternatively, the method may further comprisedetermining the current temperature of the braking medium by measuring both the temperature ofthe braking medium and measuring the temperature of the cooling medium. The |atter alternativemay for example increase the accuracy in the determination of the current temperature of the braking medium.
The present disc|osure further re|ates to a computer program, wherein said computer programcomprises program code for causing a control device to perform the method for controlling a braking system as described above.
The present disc|osure further re|ates to a computer-readable medium comprising instructions,which when executed by a control device, cause the control device to perform the method for controlling a braking system as described above.
The present disc|osure further provides a control device configured to control a braking system of avehicle. The braking system comprises a first auxiliary brake operable by a braking medium, a coolingsystem configured to cool the first auxiliary brake, and one or more additional brake means. Thecontrol device is configured to predict a future temperature of the braking medium taking intoaccount the current temperature of the braking medium and a current requested braking torque ofthe first auxiliary brake. The control device is further configured to reducing the current requestedbraking torque of the first auxiliary brake (10) to an adjusted braking torque, to be demanded fromthe first auxiliary brake (10), if the predicted future temperature of the braking medium is above apredetermined maximum temperature of the braking medium. The control device is also configuredto control the one or more additional brake means so as to compensate for the difference in brakingtorque between said current requested braking torque and the adjusted braking torque to be demanded from the first auxiliary brake.
The control device may further be configured to ta ke into account a current ambient temperatureand/or a current cooling capacity of the cooling system when predicting the future temperature of the braking medium.
Moreover, the control device may further be configured to reduce the current requested brakingtorque of the first auxiliary brake to the adjusted braking torque to be demanded from the firstauxiliary brake by reducing the current requested braking torque by a predetermined fixed amount or a percentage of the current requested braking torque.
The control device may also be configured to control the cooling system so as to increase the coolingcapacity thereof, if not already at maximum cooling capacity, if the predicted future temperature of the braking medium is above the predetermined maximum temperature of the braking medium.
The control device may further be configured to determine an appropriate adjusted braking torqueto be demanded from the first auxiliary brake, which results in a predicted future temperature of thebraking medium being equal to or lower than the predetermined maximum temperature of thebraking medium, by iterating steps of predicting a future temperature of the braking medium andreducing a current requested braking torque to an adjusted braking to be demanded from the firstauxiliary brake; and controlling the first auxiliary brake based on the obtained appropriate adjusted braking torque to be demanded from the first auxiliary brake.
The control device has the corresponding advantages described above with regard to the method for controlling a braking system.
The present disclosure also relates to a vehicle, comprising a braking system. The braking systemcomprises a first auxiliary brake operable by a braking medium, a cooling system configured to coolthe first auxiliary brake, and one or more additional brake means. The vehicle further comprises a control device as described above.BRIEF DESCRIPTION OF DRAWINGSFig. 1 schematically illustrates a side view of an example of a vehicle; Fig. 2 schematically illustrates an exemplifying embodiment of a powertrain of a vehicle; Fig. 3 schematically illustrates an exemplifying embodiment of a cooling system;Fig. 4 schematically illustrates one exemplifying embodiment of a braking system of a vehicle;Fig. 5 represents a flowchart schematically illustrating a method for controlling a braking system for a vehicle in accordance with a first exemplifying embodiment;Fig. 6 represents a flowchart schematically illustrating a method for controlling a braking systemfor a vehicle in accordance with a second exemplifying embodiment; Fig. 7 schematically illustrates a device that may constitute, comprise or be a part of a control device configured to control a braking system of a vehicle.
DETAILED DESCRIPTION The invention will be described in more detail below with reference to exemplifying embodimentsand the accompanying drawings. The invention is however not limited to the exemplifyingembodiments discussed and/or shown in the drawings, but may be varied within the scope of theappended claims. Furthermore, the drawings shall not be considered drawn to scale as some features may be exaggerated in order to more clearly illustrate the invention or features thereof. ln accordance with the present disclosure, a method for controlling a braking system for a vehicle isprovided. The braking system comprises a first auxiliary brake operable by means of a brakingmedium, and one or more additional brake means. One example of such a first auxiliary brakeoperable by means of a braking medium is a retarder. Another example of such a first auxiliary brakeis a compression brake. The one or more additional brake means may for example be selected fromthe group consisting of the service brakes of the vehicle, or any other previously known auxiliarybrake (other than the above mentioned first auxiliary brake). Examples of other auxiliary brakes,other than the first auxiliary brake, include an exhaust brake, an engine brake, and a compressionbrake. Thus, the braking system may for example comprise at least the first auxiliary brake and asecond auxiliary brake. The service brakes of the vehicle may constitute a part of the abovementioned braking system or may be a part of a constituent arrangement of the vehicle other thanthe herein discussed braking system. The braking system further comprises a cooling system configured to cool the first auxiliary brake, such as by cooling the braking medium of the first auxiliary brake. A cooling medium is circulated in a first circuit of the cooling system, and cools thebraking medium when passing through a heat exchanger. The cooling system may be a constituentarrangement shared with another system of the vehicle. For example, the cooling system may alsobe configured to cool other components of the vehicle such as a propulsion unit of the vehicle (herein also referred to as a power unit).
The method for controlling a braking system for a vehicle in accordance with the present disclosurecomprises the steps of predicting a future temperature of the braking medium, reducing a currentlyrequested braking torque from the first auxiliary brake if the predicted future temperature of thebraking medium is above a maximum temperature of the braking medium, and controlling one ormore additional brake means of the braking system so as to compensate for a loss of braking torquefrom the first auxiliary brake resulting from the reduction of the (initially) requested braking torque.
These steps will be described in more detail in the following. ln view of the fact that the present method considers a predicted future temperature for the controlof the braking system, the risk of the first auxiliary brake becoming overheated may be significantlyreduced, or (at least in some embodiments) even avoided. The reason for this is that the firstauxiliary brake may be controlled based on an adjusted braking torque lower than the initiallyrequested braking torque which over time could result in the temperature of the braking medium becoming higher that the predetermined maximum temperature thereof.
Moreover, in view of the fact that the present method considers a predicted future temperature forthe control of the braking system, the activation time of other auxiliary brakes than the first auxiliarybrake may be initiated earlier than in accordance with previously known control systems wherein analready reached temperature is considered. This is turn results in that a compensation of potentialloss of desired braking torque from the first auxiliary brake may be achieved quicker. Thereby, therisk of an undesirable acceleration of the vehicle may be minimized. Furthermore, wear of the one ormore additional brake means of the braking system may be minimized due to the activation thereofat a lower vehicle speed, the lower vehicle speed resulting from the minimization of the undesired acceleration of the vehicle.
The method for controlling a braking system in accordance with the present disclosure is performedby a control device configured to control the braking system. The control device may thus beconfigured to perform any one of the below mentioned steps of the method. The control device may comprise one or more control units. ln case of a plurality of control units, each control unit may be configured to control a certain function or a certain function may be divided between more than onecontrol units. The control of the braking system, or any constituent component thereof, may begoverned by programmed instructions. These programmed instructions typically take the forms of acomputer program which, when executed in a control device, causes the control device to effect desired forms of control action.
The method for controlling a braking system as described herein may typically be performedcontinuously. ln other words, the steps of the method may be repeated, for example with a certainpreselected frequency. The method may also be performed for example only when the first auxiliarybrake has been activated or at least a request for activation of the first auxiliary brake has been generated by an automatic system of the vehicle or by a driver of the vehicle.
As mentioned above, the method comprises a step of predicting a future temperature of the brakingmedium. The future temperature of the braking medium may be a temperature of the brakingmedium after a selected period of time has passed. ln other words, the prediction may be based on aselected period of time. The selected period of time may for example in the order of a few seconds,such as after 5 seconds, 10 seconds, 15 seconds, 20 seconds or the like. The accuracy of thepredicted future temperature of the braking medium may typically increase with smaller periods oftime. Therefore, selecting a shorter period of time when predicting the future temperature may alsoimprove the control of the braking system. However, if the prediction of the future temperature ismade for a too short period of time, it may not enable a desired control of the braking system. Thismay lead to insufficient braking of the vehicle, which in turn may cause an undesired acceleration ofthe vehicle. This is comparable with the problems associated with the prior art control systemsrelying for example on a measurement of the coolant temperature. Thus, the prediction of the futuretemperature of the braking medium may be for time which is after at least 3 seconds, prefera bly atleast 5 seconds. Thereby, an efficient control of the braking system may be achieved by enablingsufficient time for activation or increase of additional braking torque from other brake means if needed.
Predicting the future temperature of the braking medium may be made by directly predicting thefuture temperature of the braking medium. Alternatively, predicting the future temperature of thebraking medium may in practice be made by predicting a future temperature of the cooling mediumand, based on a model of the cooling system, thereby deriving a corresponding predicted future temperature of the braking medium.
The prediction of the future temperature of the braking medium is made at least based on a currenttemperature of the braking medium (in general, the current highest temperature of the brakingmedium within the braking system) and a currently requested braking torque from the first auxiliarybrake. The current temperature of the braking medium may for example be either directly orindirectly determined. A directly determined current temperature of the braking medium mayconstitute a measured temperature of the braking medium. This may be achieved by utilization of atemperature sensor arranged to determine the temperature of the braking system. An indirectlydetermined current temperature of the braking medium may for example be achieved bydetermining a cooling medium temperature, such as by a temperature sensor configured todetermine said cooling medium temperature. Based on this determined cooling mediumtemperature, the current temperature of the braking medium may be estimated using a model of thecooling system. Thus, the current temperature of the braking medium may be determined inaccordance with any previously known method in the art therefore. The currently requested brakingtorque from the first auxiliary brake may for example a currently requested braking torque from acruise control or the like, or a currently requested braking torque from a driver. The driver mayrequest a braking torque from the first auxiliary brake my activation of any known device therefore,such as a lever or a button, as known in the art. The current requested braking torque of the firstauxiliary brake, if actuated by the first auxiliary brake, generates predictable amount of heat overtime. Thus, my considering the current temperature of the braking medium and a currentlyrequested braking torque from the first auxiliary brake, it is possible to predict a future temperature of the braking medium. lf desired, it is possible to consider further parameters when predicting the future temperature ofthe braking medium. Considering further parameters when predicting the future temperature of thebraking medium may increase the accuracy of the predicted future temperature of the brakingmedium and therefore improve the control of the braking system. However, the prediction of thefuture temperature of the braking medium may become more complex with an increasing amount of considered parameters, which in turn may increase the risk of errors in the prediction. lt is however advantageous to make the prediction of a future temperature of the braking medium,not only based on the current temperature of the braking medium and the current requested brakingtorque of the first auxiliary brake, but also on the current cooling capacity of the cooling system. Forexample, if the predicted future temperature of the braking medium is above the predeterminedmaximum temperature it may be derived that the cooling capacity of the cooling system is insufficient. Then, if the cooling capacity of the cooling system is not already at the maximum cooling 11 capacity allowed by its physical constraints, a control of the cooling system so as to increase thecooling capacity thereof may be performed. By way of example, a cooling fan of the cooling systemmay be activated, if not already activated, and controlled so as to assist in the removal of thermalenergy from the cooling medium. Another example is that the flow of the cooling medium may bealtered to increase the cooling capacity of the cooling system. Naturally, both the cooling fan and theflow of the cooling medium may be controlled so as to increase the cooling capacity of the coolingsystem. Thereafter, a second future temperature of the braking medium (at the increased coolingcapacity) may be predicted and only if said second predicted future temperature is above thepredetermined maximum temperature of the braking medium is the step of controlling the one ormore additional brake means so as to compensate for the loss of braking torque from the first auxiliary brake resulting from the reduction of the requested braking torque performed.
Moreover, predicting the future temperature of the braking medium may not only based on thecurrent temperature of the braking medium and the current requested braking torque of the firstauxiliary brake, but also on the ambient temperature, i.e. the temperature outside the vehicle. Theambient temperature of the vehicle may be considered when predicting the future temperature ofthe braking medium in addition to the cooling capacity of the cooling system, or it may be consideredeven if the cooling capacity of the cooling system would not be considered when predicting the temperature of the braking medium.
Examples of additional parameters that may be considered when predicting the future temperatureof the braking medium, if available, include a positioning system in combination with map data(including information regarding inclination of road), experienced current inclination of roaddetermined for example by an inclination sensor of the vehicle, information from look-ahead systemsdetecting upcoming road properties and/or traffic conditions, possible additional thermal load on thecooling system, etc. The prediction of the future temperature of the braking medium may consider one or more of these parameters in any combination.
As mentioned above, the method for controlling the braking system in accordance with the presentdisclosure further comprises a step of reducing a currently requested braking torque from the firstauxiliary brake if the predicted future temperature of the braking medium is above a maximumtemperature of the braking medium. By reducing the current requested braking torque to anadjusted braking torque to be demanded from the first auxiliary brake, it may be possible to avoid anincrease of the temperature of the braking medium above the predetermined maximum temperature. ln other words, the first auxiliary brake may be activated with a smaller braking torque 12 and thereby not generate as much heat as would have been generated if the originally requested braking torque would have been continuously used.
When having reduced the requested braking torque of the first auxiliary brake to an adjusted brakingtorque to be demanded from the first auxiliary brake, it is possible to control the first auxiliary brakebased on the adjusted braking torque to be demanded from the first auxiliary brake immediately.Thereafter, the step of predicting a future temperature based on the current temperature of thebraking medium and a current requested braking torque (which in such a case thus corresponds tothe adjusted braking torque to be demanded obtained from the first iteration of the method) may berepeated and the resulting, second, predicted future temperature of the braking medium would thenused when repeating the subsequent steps of the method. This would result in the method graduallyarriving at an appropriate braking torque from the first auxiliary brake while avoiding overheating, more or less by trial and error.
Alternatively, when having reduced the requested braking torque of the first auxiliary brake to anadjusted braking torque to be demanded from the first auxiliary brake, the adjusted braking torqueto be demanded from the first auxiliary brake may be used in a step of predicting a second futuretemperature of the braking medium based on the current temperature of the braking medium andsaid adjusted braking torque to be demanded from the first auxiliary brake before the first auxiliarybrake is actually controlled to any adjusted braking torque to be demanded from the first auxiliarybrake. This alternative allows for obtaining an appropriate adjusted braking torque to be demandedfrom the first auxiliary brake, which directly results in a temperature of the braking medium that isbelow the predetermined maximum temperature, by repeating the prediction of a futuretemperature and comparison thereof with the predetermined maximum temperature until saidappropriate adjusted braking torque to be demanded from the first auxiliary brake has beendetermined. The first auxiliary brake can thereafter be controlled to the appropriate adjusted braking torque.
A reduction of the current requested braking torque from the first auxiliary brake to an adjustedbraking torque to be demanded from the first auxiliary brake may be made with a fixed amount ofbraking torque, for example 50 Nm, 100 Nm or 200 Nm. Alternatively, the reduction may be made by a percentage of the requested braking torque, for example 2.5%, 5% or 7.5%.
As mentioned above, the method for controlling the braking system in accordance with the present disclosure further comprises a step of controlling one or more additional brake means of the braking 13 system so as to compensate for the loss of braking torque from the first auxiliary brake resultingfrom the reduction of the requested braking torque. The step of controlling the one or moreadditional brake means so as to compensate for the loss of braking torque may be performed by anypreviously known process therefore. However, in contrast to previously known controlling methodsof a braking system, the step of controlling the one or more additional brake means so as tocompensate for the low of braking torque will be initiated at an earlier point in time as describedabove. Therefore, the risk of undesirable acceleration of the vehicle is further minimized. This alsohas the beneficial effect that the braking effect of such one or more additional brake means will beeffectuated at a lower vehicle speed than if the vehicle has been able to accelerate until theactivation thereof has occurred. This also has the advantage of minimizing the damage or wear of such one or more additional brake means.
The step of controlling one or more additional brake means of the braking system so as tocompensate for the loss of braking torque from the first auxiliary brake may comprise activation ofsuch one or more additional brake means, if not already activated. lf the one or more additionalbrake means is already activated, the control thereof so as to compensate for the loss of brakingtorque may comprise increasing the braking torque of said one or more brake means. lf the auxiliarybrakes of the braking system are not able to provide the desired braking torque for maintaining avehicle speed, for example in a downhill slope, the method may further comprise automatically activating the service brakes of the vehicle to deliver an appropriate braking effect.
The above discussed method for controlling a braking system according to the present disclosuremay naturally be supplemented with other forms of control of the braking system. For example, if itis detected that the current temperature of the braking medium is above the predeterminedmaximum temperature of the braking medium, the usage of the first auxiliary brake may be reducedimmediately to avoid for example damage of the braking medium or constituent components of the first auxiliary brake.
Figure 1 schematically illustrates a side view of an example of a vehicle 1. The vehicle 1 comprises apowertrain 3 comprising a power unit 2, such as a combustion engine, and a gearbox 4. A clutch (notshown) may be arranged between the power unit 2 and the gearbox 4. The gearbox 4 is connected tothe driving wheels 5 of the vehicle 1 via an output shaft 6 of the gearbox 4. The gearbox 4 is adaptedto provide a plurality of gear ratios. The gearbox 4 may for example be an automated manual gearbox (AMT). Alternatively, the gearbox 4 may be a manual gearbox. 14 The vehicle 1 may be, but is not limited to, a heavy vehicle, e.g. a truck or a bus. Furthermore, thevehicle may be a hybrid vehicle comprising a second power unit in the form of an electric motor (not shown) in addition to the combustion engine 2.
Figure 2 schematically illustrates an exemplifying embodiment of a vehicle powertrain 3, such as apowertrain of the vehicle 1 shown in Figure 1. The powertrain 3 comprises a power unit 2, such as acombustion engine. The combustion engine may comprise an engine brake. The powertrain furthercomprises a gearbox 4 connected to the power unit 2 via a clutch 9. The output shaft 6 of thegearbox 4 is connected to the driving wheels 5 via for example a differential 11 and a drive shaft 12.The powertrain 3 further comprises service brakes 7 arranged at the driving wheels 5. Thepowertrain 3 further comprises an auxiliary brake in the form of a retarder 10. The retarder 10 isconnected to the output shaft 6 of the gearbox 4. Moreover, the powertrain 3 comprises a cooling system 8 adapted to cool the power unit 2 and/or the retarder 10.
As shown in Figure 2, the powertrain 3 may further comprise a control device 100. The control device100 may be configured to control one or more of the constituent components of the vehiclepowertrain 3. The control device 100 may comprise one or more control units. The responsibility fora specific function or control may be divided between two or more of the control units. One or moreof the control units may be implemented in the form of a computer. The control device 100 may forexample be connected to the power unit 2, the gearbox 4, the retarder 10 and optionally the clutch9, as shown in Figure 2. The control device 100 may also be connected to any other constituentcomponent of the vehicle powertrain 3, even though not illustrated in the figure, if desired. Theconnections of the control device 100 to any constituent component of the vehicle powertrain 3 may be in the form of physical connection(s) and/or wireless connection(s).
The control of constituent components in the vehicle powertrain 3 may be governed by programmedinstructions. These programmed instructions typically take the forms of a computer program which,when executed in a computer or control unit, causes the computer or control unit to effect desiredforms of control action, for example the steps of the method disclosed herein. As described above, such a computer or control unit may be or constitute a part of the control device 100.
Figure 3 schematically illustrates one exemplifying embodiment of a cooling system 8, such as thecooling system of the powertrain shown in Figure 2. The cooling system 8 comprises a first circuit 16in which a cooling medium, such as water, may be circulated. The cooling system further comprises a second circuit 17, in which a braking medium (such as oil) of a retarder 10 may be circulated. The first circuit 16 may comprise a coolant pump 13 arranged to control the circulation of the coolingmedium in the first circuit 16. The coolant pump 13 may typically be driven by the combustion engine 2 via a driving belt or the like. ln the first circuit 16, the cooling medium is led to the combustion engine 2 to effectuate coolingthereof. ln the combustion engine, the cooling medium may be circulated through cooling ducts, asknown in the art, to cause cooling of the combustion engine. After the cooling medium has passedthe combustion engine 2, it is led to a heat exchanger 14 in which it may be used to cool the brakingmedium flowing in the second circuit 17. The cooling medium is, in the first circuit, led from the heat exchanger 14 to a radiator 15 in which it is intended to give off thermal energy absorbed from the combustion engine 2 and the heat exchanger 14. The cooling system may further comprises a fan 18.
The fan 18 may for example be driven by the engine. The fan 18 is arranged in the vicinity of theradiator 15 and may thus assist in the removal of thermal energy from the cooling medium in thefirst circuit. During operation of the cooling system, the fan may typically remain deactivated if theradiator alone is capa ble of removing a sufficient amount of the thermal energy absorbed by thecooling medium. According to one alternative, the fan may be activated with different rotationalspeed depending on the need for assistance in the cooling of the cooling medium. Alternatively, itmay, for ease of control, be fully activated with a maximum rotational speed as soon as the radiatoralone is not sufficient for removal of an intended amount of adsorbed thermal energy of the cooling medium.
The first circuit 16 may comprise one or more temperature sensors adapted to determine thetemperature of the cooling medium when circulating in the first circuit 16. As shown in Figure 3, afirst temperature sensor 20a may be arranged upstream of the combustion engine. The first sensor20a is thus able to determine the temperature of the cooling medium entering the com bustionengine. Moreover, a second temperature sensor 20b may be arranged downstream of the heatexchanger 14. The second temperature sensor 20b is thus able to determine the temperature of thecooling medium when leaving the heat exchanger 14. lf desired, it is also possible to arrange a thirdtemperature sensor 20c downstream of the combustion engine but upstream of the heat exchanger14. Thereby, it may for example be possible to determine the contribution of the combustion engine and the braking medium, respectively, to the increased temperature of the cooling medium.
Furthermore, the second circuit 17 may comprise one or more temperature sensors adapted todetermine the temperature of the braking medium. ln Figure 3, a fourth temperature sensor 21a is arranged in the second circuit upstream of the retarder 10. The fourth temperature sensor is thus 16 able to determine the temperature of the braking medium before it enters into the retarder 10. Afifth temperature sensor 21b may be arranged downstream of the retarder 10 (upstream of the heatexchanger 14). The fifth temperature sensor is thus able to determine the temperature of thebraking medium after having passed through the retarder, but before the braking medium has beencooled in the heat exchanger 14. Such a fifth temperature sensor 21b may thus be used to determine a highest current temperature of the braking medium in the second circuit 17. lt shall be recognised that although Figure 3 illustrates an alternative wherein the cooling mediumand the braking medium flows in opposite directions through the heat exchanger (as shown by thearrows), a configuration wherein the cooling medium and the braking medium flow in substantiallythe same direction through the heat exchanger is also possible. ln the latter case, the flow of thebraking medium through the second circuit would thus be in a direction opposite to the direction illustrated by the arrow in the second circuit 17.
Figure 4 schematically illustrates a braking system 30 for a vehicle according to one exemplifyingembodiment. The braking system 30 comprises a first auxiliary brake 10 operable by a brakingmedium. The first auxiliary brake may for example be a retarder. The braking system furthercomprises a cooling system 8 configured to cool the first auxiliary brake 10. The braking systemfurther comprises a second auxiliary brake 25. The second auxiliary brake 25 may for example be anexhaust brake, an engine brake or the like. The braking system may optionally further comprise theservice brakes 7 of the vehicle. The braking system further comprises a control device 100, forexample any one of the control devices described herein. The braking system further comprises afirst temperature determining device 26 configured to determine a current temperature of thebraking medium of the first auxiliary brake 10. The braking system further comprises a first controlunit 27, configured to determine or receive data relating to a requested braking torque of the firstauxiliary brake. The braking system may further comprise a second temperature determining device28 configured to determine an ambient temperature. Moreover, the braking system may comprise asecond control unit 29, configured to determine or receive data relating to a current cooling capacity of the cooling system 8.
Figure 5 represents a flowchart schematically illustrating a method for controlling a braking systemfor a vehicle according to a first exemplifying em bodiment of the present disclosure. The methodcomprises a first step S110 of, based on a current temperature of the braking medium and a currentrequested braking torque of the first auxiliary brake, predicting a future temperature Tp of the braking medium. The method then comprises a step S120 of comparing the predicted future 17 temperature Tp of the braking medium with a predetermined maximum temperature Tmax of thebraking medium. lf the predicted temperature Tp of the braking medium is not above thepredetermined maximum temperature Tmax, the step S110 may be repeated after a preselectedtime. However, if the predicted temperature Tp of the braking medium is above the predeterminedmaximum temperature Tmax, the method proceeds to step S130. Step 130 comprises reducing thecurrent requested braking torque of the first auxiliary brake to an adjusted braking torque to berequested from the first auxiliary brake. Thereafter, the method may optionally proceed to stepS110, wherein a future temperature of the braking medium is predicted considering the adjustedbraking torque to be demanded from the first auxiliary brake instead of the (previously) requestedbraking torque. Moreover, after step S130, the method proceeds to step S140. Step S140 comprisescontrolling the one or more additional brake means to compensate for the difference in brakingtorque between the (initially) requested braking torque and the adjusted braking torque to be demanded from the first auxiliary brake.
Figure 6 represents a flowchart schematically illustrating a method for controlling a braking systemfor a vehicle according to a second exemplifying embodiment of the present disclosure. The methodshown in Figure 6 comprises, a first step S110' of, based on a current temperature of the brakingmedium, a current requested braking torque of the first auxiliary brake and the cooling capacity ofthe cooling system, predicting a future temperature Tp of the braking medium. The methodillustrated in Figure 6 further comprises the steps S120, S130 and S140 discussed above withreference to Figure 5. However, in contrast to the method illustrated in Figure 5, the present methodof Figure 6 also comprises a step S122 following step S120. Step 122 comprises controlling if thecooling capacity of the cooling system is at its maximum. lf it is determined in step S122 that thecooling capacity is not at the maximum cooling capacity which the cooling system is able to provide,the method proceeds to step S124. Step S124 comprises controlling the cooling system so as toincrease the cooling capacity thereof. This may for example comprise increasing a rotational speed ofa fan 18 of the cooling system 8 (compare with Figure 3). The method then proceeds to step S110,wherein a new future temperature of the braking medium is predicted taking into account also thenew (increased) cooling capacity of the cooling system. When it is determined in step S130 that thecooling capacity of the cooling system is at its maximum cooling capacity, the method proceeds to step S130.
Figure 7 schematically illustrates an exemplifying embodiment of a device 500. The control device100 described above may for example comprise the device 500, consist of the device 500, or be comprised in the device 500. 18 The device 500, shown in the figure, comprises a non-volatile memory 520, a data processing unit510 and a read/write memory 550. The non-volatile memory 520 has a first memory element 530 inwhich a computer program, e.g. an operating system, is stored for contro||ing the function of thedevice 500. The device 500 further comprises a bus controller, a serial communication port, I/Omeans, an A/D converter, a time and date input and transfer unit, an event counter and aninterruption controller (not depicted). The non-volatile memory 520 has also a second memory element 540.
There is provided a computer program P that comprises routines for contro||ing a braking system of avehicle, such as a braking system described above. The computer program comprises routines forpredicting a future temperature of the braking medium (of the first auxiliary brake) based on acurrent temperature of the braking medium and a current requested braking torque of the firstauxiliary brake. The computer program further comprises routines for, if the predicted futuretemperature of the braking medium is above a predetermined maximum temperature of the brakingmedium, reducing the current requested braking torque of the first auxiliary brake to an adjustedbraking torque to be demanded from the first auxiliary brake. The computer program furthercomprises routines for contro||ing the one or more additional brake means so as to compensate forthe difference in braking torque between said current requested braking torque and the adjustedbraking torque to be demanded from the first auxiliary brake. The computer program may furthercomprise routines for requesting the first auxiliary bra ke to deliver said adjusted braking torque to be demanded from the first auxiliary brake.
The program P may be stored in an executable form or in a compressed form in a memory 560 and/or in a read/write memory 550.
The data processing unit 510 may perform certain functions. For example, the data processing unit510 may effect a certain part of the program stored in the memory 560 or a certain part of the program stored in the read/write memory 550.
The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-volatile memory 520 may be intended for communication with the data processing unit 510 via adata bus 512. The separate memory 560 may be intended to communicate with the data processingunit 510 via a data bus 511. The read/write memory 550 may be adapted to communicate with the data processing unit 510 via a data bus 514. 19 When data are received on the data port 599, they may be stored temporarily in the second memoryelement 540. When input data received have been temporarily stored, the data processing unit 510may be prepared to effect code execution according to a computer program comprising programcode for causing a control device to perform the method (or parts thereof) for contro||ing a braking system for a vehicle as described herein.
Parts of the methods herein described may be effected by the device 500 by means of the dataprocessing unit 510 which runs the program stored in the memory 560 or the read/write memory 550. When the device 500 runs the program, methods herein described are executed.

Claims (4)

1.
2.
3.
4. A method for controlling a braking system (30) for a vehicle (1), the method performed by acontrol device (100),the braking system (30) comprising: a first auxiliary brake (10) operable by a braking medium; a cooling system (8) configured to cool the first auxiliary brake (10), and one or more additional brake means (7, 25);the method comprising steps of: (a) based on a current temperature of the braking medium and a current requestedbraking torque of the first auxiliary brake, predicting a future temperature (Tp) ofthe braking medium, (S110), (b) if the predicted future temperature (Tp) of the braking medium is above apredetermined maximum temperature (Tmax) of the braking medium, reducingthe current requested braking torque of the first auxiliary brake (10) to anadjusted braking torque to be demanded from the first auxiliary brake (10),(S130), and(c) controlling the one or more additional brake means (7, 25) to compensate for the difference in braking torque between said current requested braking torque and the adjusted braking torque to be demanded from the first auxiliary brake (10), (S140). The method according to claim 1, wherein predicting the future temperature (Tp) of thebraking medium further comprises taking into account the current ambient temperature and/or the current cooling capacity of the cooling system (8). The method according to any one of claims 1 or 2, wherein step (b) comprises reducing thecurrent requested braking torque by a predetermined fixed amount of torque or a percentage of the current requested braking torque. The method according to any one of the preceding claims, further comprisingafter step (b), repeating step (a) with usage of the adjusted braking torque to bedemanded from the first auxiliary brake (10) as the current requested braking torque of the first auxiliary brake (10) in step (a), and 21 iterating steps (a) and (b) until an appropriate adjusted braking torque to bedemanded from the first auxiliary brake (10) which results in a predicted future temperature(Tp) of the braking medium being equal to or lower than the predetermined maximum temperature (Tmax) of the braking medium has been obtained. The method according to any one of the preceding claims, further comprising, after step (a),a step of: (al) if the predicted future temperature (Tp) of the braking medium is above thepredetermined maximum temperature (Tmax) of the braking medium, increasing the coolingof the auxiliary brake (10) by increasing the cooling capacity of the cooling system (8), if notalready at maximum cooling capacity; and optionally a step of: (a2) before step (b), repeating step (a) taking into account the increased cooling capacity of the cooling system (8). The method according to any one of the preceding claims, further comprising determiningthe current temperature of the braking medium by measuring the temperature of thebraking medium and/or by measuring the temperature of a circulating cooling medium in the cooling system (8). A computer program (P) comprising program code for causing a control device (100) to perform the method according to any one of the preceding claims. A computer-readable medium comprising instructions, which when executed by a controldevice (100), cause the control device (100) to perform the method according to any one of claims 1 to 7. A control device (100) configured to control a braking system (30) of a vehicle (1),the braking system (30) comprising:a first auxiliary brake (10) operable by a braking medium;a cooling system (8) configured to cool the first auxiliary brake (10), andone or more additional brake means (7, 25);wherein the control device (100) is configured to predict a future temperature (Tp) of thebraking medium taking into account the current temperature of the braking medium and a current requested braking torque of the first auxiliary brake; 10. 11. 12. 13. 14. 22 the control device (100) further configured to reducing the current requested braking torqueof the first auxiliary brake (10) to an adjusted braking torque, to be demanded from the firstauxiliary brake (10), if the predicted future temperature (Tp) of the braking medium is abovea predetermined maximum temperature (Tmax) of the braking medium; the control device (100) further configured to control the one or more additional brakemeans (7, 25) so as to compensate for the difference in braking torque between said currentrequested braking torque and the adjusted braking torque to be demanded from the first auxiliary brake (10). The control device (100) according to claim 9, further configured to take into account acurrent ambient temperature and/or a current cooling capacity of the cooling system (8) when predicting the future temperature (Tp) of the braking medium. The control device (100) according to any one of claims 9 and 10, further configured toreduce the current requested braking torque of the first auxiliary brake to the adjustedbraking torque to be demanded from the first auxiliary brake by reducing the currentrequested braking torque by a predetermined fixed amount or a percentage of the current requested braking torque. The control device (100) according to any one of claim 9 to 11, further configured to controlthe cooling system (8) so as to increase the cooling capacity thereof, if not already atmaximum cooling capacity, if the predicted future temperature (Tp) of the braking medium is above the predetermined maximum temperature (Tmax) of the braking medium. The control device (100) according to any one of claims 9 to 12, further configured todetermine an appropriate adjusted braking torque to be demanded from the first auxiliarybrake, which results in a predicted future temperature (Tp) of the braking medium beingequal to or lower than the predetermined maximum temperature (Tmax) of the brakingmedium, by iterating steps of predicting a future temperature of the braking medium andreducing a current requested braking torque to an adjusted braking to be demanded fromthe first auxiliary brake (10), and controlling the first auxiliary brake (10) based on the obtained appropriate adjusted braking torque to be demanded from the first auxiliary brake. A vehicle (1) comprising a braking system (30), 23 the braking system (30) comprising:a first auxiliary brake (10) operable by means of a braking medium;a cooling system (8) configured to cool the first auxiliary brake; andone or more additional brake means (7, 25);the vehicle (1) further comprising a control device (100) according to any one of claims 9 to 14.
SE1950479A 2019-04-17 2019-04-17 Method for controlling a braking system, control device, computer program, computer- readable medium and vehicle SE543381C2 (en)

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JP3743692B2 (en) * 1997-03-26 2006-02-08 株式会社小松製作所 Retarder automatic control device
SE522431C2 (en) * 2000-10-20 2004-02-10 Scania Cv Ab Method and arrangement for controlling braking of a hydrodynamic auxiliary brake in a vehicle
US9988024B2 (en) * 2015-08-26 2018-06-05 Caterpillar Inc. Retarder integrated braking system and method
US10562509B2 (en) * 2017-07-06 2020-02-18 GM Global Technology Operations LLC Brake temperature monitoring system
GB2566488B (en) * 2017-09-15 2020-04-15 Jaguar Land Rover Ltd Vehicle brake system energy comparison module

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