SE2050990A1 - Control device and method for controlling a hydraulic auxiliary brake arrangement - Google Patents

Control device and method for controlling a hydraulic auxiliary brake arrangement

Info

Publication number
SE2050990A1
SE2050990A1 SE2050990A SE2050990A SE2050990A1 SE 2050990 A1 SE2050990 A1 SE 2050990A1 SE 2050990 A SE2050990 A SE 2050990A SE 2050990 A SE2050990 A SE 2050990A SE 2050990 A1 SE2050990 A1 SE 2050990A1
Authority
SE
Sweden
Prior art keywords
hydraulic
shaft
auxiliary brake
brake arrangement
control device
Prior art date
Application number
SE2050990A
Other versions
SE544474C2 (en
Inventor
Karl Vestgöte
Patrick Hanstad
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 SE2050990A priority Critical patent/SE544474C2/en
Priority to DE102021121205.7A priority patent/DE102021121205A1/en
Publication of SE2050990A1 publication Critical patent/SE2050990A1/en
Publication of SE544474C2 publication Critical patent/SE544474C2/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
    • 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
    • B60T10/00—Control or regulation for continuous braking making use of fluid or powdered medium, e.g. for use when descending a long slope
    • 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
    • B60W10/18—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
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/02—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to ambient conditions
    • B60W40/06—Road conditions
    • 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
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/02—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to ambient conditions
    • B60W40/06—Road conditions
    • B60W40/076—Slope angle of the road
    • 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
    • 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
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/02—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to ambient conditions
    • B60W40/06—Road conditions
    • B60W40/072—Curvature of the road
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transportation (AREA)
  • Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Fluid Mechanics (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Human Computer Interaction (AREA)
  • Regulating Braking Force (AREA)
  • Transmission Of Braking Force In Braking Systems (AREA)
  • Braking Systems And Boosters (AREA)

Abstract

A control device (100) and a method for controlling a hydraulic auxiliary brake arrangement (8, 9) of a vehicle powertrain (2) are provided. The hydraulic auxiliary brake arrangement (8, 9) comprises a rotatable first shaft (20) connectable to a second shaft (24) of the vehicle powertrain onto which a braking torque is to be exerted by the hydraulic auxiliary brake arrangement. The hydraulic auxiliary brake arrangement further comprises a rotor (30), connected to the first shaft, and a stator (32). The rotor (30) and the stator (32) jointly form a toroidal volume (33). The hydraulic brake arrangement further comprises a hydraulic circuit (40) connected to the toroidal volume (33), a reservoir (36) for hydraulic fluid, a pump (34) configured to transfer hydraulic fluid from the reservoir to the hydraulic circuit, as well as a control valve (50) configured to control the hydraulic pressure in the hydraulic circuit. In accordance with the method, the pump is activated based on a predicted future driverinitiated demand for brake torque and the control valve is controlled so that a hydraulic pressure in the hydraulic circuit is lower than a preselected threshold value. A computer program, a computerreadable medium and a vehicle (1) are also disclosed.

Description

CONTROL DEVICE AND METHOD FOR CONTROLLING A HYDRAULIC AUXILIARY BRAKEARRANGEMENT TECHNICAL FIELD The present disclosure relates in general to a method for controlling a hydraulic auxiliary brakearrangement and a control device configured to control a hydraulic auxiliary brake arrangement. Thepresent disclosure further relates in general to a computer program, a computer-readable medium as well as a vehicle.
BACKGROUND A vehicle may, in addition to service brakes, be equipped with various types of auxiliary brake systems, such as a hydraulic auxiliary brake arrangement.
One example of a hydraulic auxiliary brake is a retarder in which a hydraulic fluid, typically oil, is usedas a braking medium. The retarder may for example be engaged to an output shaft of a gearbox ofthe vehicle powertrain, and be configured to provide a braking torque to said output shaft. Aretarder need not be engaged to the output shaft of the gearbox, but may be arranged at otherpositions of the vehicle powertrain as desired. The retarder comprises a stator and a rotor, the rotorbeing connected to a retarder shaft which in turn is connected to for example the output shaft of thegearbox. The rotor and the stator together form a toroidal volume into which the braking medium isintroduced at a desired pressure when a braking torque is to be exerted by the retarder. The brakingeffect is achieved by a created flow in the toroidal volume which results in reaction forces reducingthe rotational speed of the rotor. Thereby, the travelling speed of the vehicle may be reduced. lnorder to reduce energy losses when no braking torque is desired from the retarder, retarders thatmay be disconnected from the vehicle powertrain have been developed and are today frequently used in heavy vehicles.
Another example of a hydraulic auxiliary brake is a water retarder, sometimes referred to as apretarder. lt functions in essentially the same way as a conventional oil retarder, but generally utilizes engine coolant (water) as the braking fluid. A water retarder may be mounted on the front of the engine and connected directly to the crankshaft of the engine. A water retarder may alternatively be arranged at other positions in the vehicle powertrain, if desired. lt is important that the response time of a hydraulic auxiliary brake arrangement is short when abraking torque therefrom is demanded. A long response time entails a lack of braking effect from thehydraulic auxiliary brake arrangement, which entails an exaggerated use of the vehicle's service brakes. This in turn increases the wear of the service brakes.
EP 3000675 A1 discloses a method for controlling a connectible and disconnectable retarder by acruise control. When the retarder is connected, a determination is made based on a simulatedvelocity profile whether an adverse impact on the velocity development of the vehicle will arise if theretarder is connected. lf no adverse impact arises, the retarder is controlled to remain in theconnected state. Otherwise, it is disconnected. lt is furthermore described that the retarder may beconnected before a braking requirement arises at a point in time which takes into account the time required to prepare a disconnected reta rder from braking from its disconnected state.
SUMMARY The object of the invention is to reduce the response time of a hydraulic auxiliary brake arrangement when a driver of a vehicle demands braking torque from the hydraulic auxiliary brake arrangement.
The object is achieved by the su bject-matter of the appended independent claims. ln accordance with the present disclosure, a method for controlling a hydraulic auxiliary brakearrangement of a vehicle powertrain is provided. The method is performed by a control device. Thehydraulic auxiliary brake arrangement comprises a rotatable first shaft connectable to a second shaftof the vehicle powertrain. The hydraulic auxiliary brake arrangement further comprises a rotor,connected to the first shaft, and a stator, which together with the rotor forms a toroidal volume intowhich hydraulic fluid may be introduced. The hydraulic brake arrangement further comprises ahydraulic circuit connected to the toroidal volume, a reservoir for hydraulic fluid, a pump configuredto transfer hydraulic fluid from the reservoir to the hydraulic circuit, and a control valve configured to control the hydraulic pressure in the hydraulic circuit. The method comprises the steps of: based on a predicted future driver-initiated demand for brake torque from thehydraulic auxiliary brake arrangement, activating the pump so as to transfer hydraulic fluid from thereservoir to the hydraulic circuit; and controlling the control valve so that a hydraulic pressure in the hydraulic circuit is lower than a preselected threshold value.
Thereby, the time until the hydraulic auxiliary brake arrangement is able to provide a demandedbraking torque is considerably reduced. This is due to the hydraulic circuit being pre-filled withhydraulic fluid based on a prediction that the driver may be demanding a braking torque from thehydraulic auxiliary brake arrangement in the near future. This in turn also minimizes the wear of theservice brakes over time since there is a lower likelihood that the driver would utilize the servicebrakes to compensate for a slow response time of the hydraulic auxiliary brake arrangement.Furthermore, in view of the fact that the control valve controls the pressure in the hyd raulic circuit tobe lower than a preselected threshold value, it is ensured that the hydraulic auxiliary brakearrangement does not provide an undesired braking torque before the driver initiates a demand therefore.
Moreover, the present method also enables removing a possible accumulator, conventionally used toreduce the response time of the hydraulic auxiliary brake arrangement, from the hydraulic auxiliary brake arrangement.
The method may further comprise a step of predicting a future driver-initiated demand for braketorque from the hydraulic auxiliary brake arrangement based on vehicle speed, vehicle load and mapdata. Thereby, the predicted future driver-initiated demand for brake torque from the hydraulicauxiliary brake arrangement, based on which the activation of the pump is performed, is achieved. Byutilizing the vehicle speed, vehicle load and map data for the prediction, a good accuracy of theprediction of a future driver-initiated demand for brake torque from the hydraulic auxiliary brakearrangement may be achieved. Thereby, the risk of undesirable energy losses which may lead to anincrease in fuel consumption of the vehicle is minimized while at the same time ensuring a shortactivation time of the hydraulic auxiliary brake arrangement when demanded by a driver of the vehicle.
The pump may be driven by rotation of the first shaft. ln such a case, the step of activating the pumpmay be performed by connecting the first shaft of the hydraulic auxiliary brake arrangement with the second shaft of the vehicle powertrain. Thereby, the first shaft will start to rotate with a rotational speed proportional with the rotational speed of the second shaft. The rotation of the first shaftthereby drives the pump, and the pump is therefore able to pump hydraulic fluid into the hydraulic circuit.
The step of controlling the control valve so that a hydraulic pressure in the hydraulic circuit is lowerthan a preselected threshold value may further comprise controlling the control valve so that thehydraulic pressure in the hydraulic circuit is above a pressure at which the hydraulic auxiliary brakearrangement exerts a brake torque on the second shaft of the vehicle powertrain. Thereby, a smallbraking torque on the second shaft is achieved while at the same time being sufficiently low that itdoes not cause any substantial increase in the fuel consumption of the vehicle. This pressure in thehydraulic circuit further reduces the activation time of the hydraulic auxiliary brake arrangement,when a demand for brake torque therefore is issued, since it is ensured that the hydraulic circuit isfilled with a sufficient quantity of hydraulic fluid for the hydraulic auxiliary brake arrangement being able to provide any demanded braking torque therefrom (by control of the control valve).
The method may further comprise a step of, based on a determination that the predicted futuredriver-initiated demand for brake torque from the hydraulic auxiliary brake arrangement was notdemanded as predicted, disconnecting the hydraulic auxiliary brake arrangement from the vehiclepowertrain. Thereby, the energy losses in the vehicle powertrain caused by the hydraulic auxiliarybrake arrangement when connected may be minimized. This in turn reduces the fuel consumption of the vehicle.
The hydraulic auxiliary brake arrangement may be a retarder, such as a water retarder or an oilretarder. lrrespectively of the braking medium of the retarder, the second shaft may be an engineshaft, an input shaft of a gearbox of the vehicle powertrain, or an output shaft of a gearbox of the vehicle powertrain.
The present disclosure further relates to a computer program comprising instructions which, when executed by a control device, cause the control device to carry out the method as described above.
The present disclosure further relates to a computer-readable medium comprising instructionswhich, when executed by a control device, cause the control device to carry out the method as described above.
Moreover, in accordance with the present disclosure, a control device configured to control ahydraulic auxiliary brake arrangement of a vehicle powertrain is provided. The hydraulic auxiliarybrake arrangement comprises a rotatable first shaft connecta ble to a second shaft of the vehiclepowertrain. The hydraulic auxiliary brake arrangement further comprises a rotor, connected to thefirst shaft, and a stator, which together with the rotor forms a toroidal volume into which hydraulicfluid may be introduced. The hydraulic brake arrangement further comprises a hydraulic circuitconnected to the toroidal volume, a reservoir for hydraulic fluid, a pump configured to transferhydraulic fluid from the reservoir to the hydraulic circuit, and a control valve configured to controlthe hydraulic pressure in the hydraulic circuit. The control device is configured to, based on apredicted future driver-initiated demand for brake torque from the hydraulic auxiliary brakearrangement, activate the pump so as to transfer hydraulic fluid from the reservoir to the hydrauliccircuit. The control device is further configured to, when the pump has been activated, control thecontrol valve so that a hydraulic pressure in the hydraulic circuit is lower that a preselected threshold value.
The control device has the same advantages as described above for the corresponding method for controlling a hydraulic auxiliary brake arrangement of a vehicle powertrain.
The control device may further be configured to predict the future driver-initiated demand for braketorque from the hydraulic auxiliary brake arrangement based on vehicle speed, vehicle load and map data. ln case the pump is driven by rotation of the first shaft, the control device may be configured toactive the pump by connecting the first shaft of the hydraulic auxiliary brake arrangement with the second shaft of the vehicle powertrain so that the rotata ble first shaft starts to rotate.
The control device may further be configured to control the control valve so that the hydraulicpressure in the hydraulic circuit is above a pressure at which the hydraulic auxiliary brakearrangement exerts a preselected brake torque on the second shaft of the vehicle powertrain at apoint in time prior to the point in time of the predicted future driver-initiated demand for brake torque from the auxiliary brake arrangement.
The control device may further be configured to disconnect the first shaft of the hydraulic auxiliary brake arrangement from the second shaft of the vehicle powertrain based on a determination that the predicted future driver-initiated demand for brake torque from the hydraulic auxiliary brake arrangement was not demanded as predicted.
The present disclosure further relates to a vehicle. The vehicle comprises a hydraulic auxiliary brake arrangement and the control device as described above.
BREIF DESCRIPTION OF DRAWINGS Fig. 1 schematically illustrates a side view of a vehicle; Fig. 2 schematically illustrates cross sectional view of an exemplifying em bodiment of a hydraulic auxiliary brake arrangement; Fig. 3 represents a flowchart schematically illustrating a method for controlling a hydraulicauxiliary brake arrangement according to an exemplifying embodiment of the present disclosure; Fig. 4 schematically illustrates a device that may constitute, comprise or be a part of a control device configured to control a hydraulic auxiliary brake arrangement.
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 hydraulic auxiliary brakearrangement of a vehicle powertrain is provided. The hydraulic auxiliary brake arrangement may be aretarder, either using oil or water as the braking medium. The method is performed by a controldevice. The hydraulic auxiliary brake arrangement comprises a rotata ble first shaft connecta ble to asecond shaft of the vehicle powertrain. The second shaft constitutes the shaft on which the hydraulic auxiliary brake arrangement is intended to apply a braking torque when activated. The hydraulic auxiliary brake arrangement further comprises a rotor, connected to the first shaft, and a stator. Thestator and the rotorjointly form a toroidal volume into which hydraulic fluid may be introduced forthe purpose of creating a braking effect. The hydraulic brake arra ngement further comprises ahydraulic circuit connected to the toroidal volume, a reservoir for hydraulic fluid, a pump configuredto transfer hydraulic fluid from the reservoir to the hydraulic circuit, as well as a control valve configured to control the hydraulic pressure in the hydraulic circuit.
The present method is performed while the vehicle is travelling. ln other words, the method is notintended to be performed for example when the vehicle is at stand-still or not operated. The reasontherefore is that it cannot be expected that the driver will demand a braking torque from thehydraulic auxiliary brake when the vehicle is not travelling. Consequently, there is no need toperform the present method at occasions when the vehicle is travelling at a travelling speed whichcorresponds to a rotational speed of an output shaft of a gearbox (which also corresponds to a rotational speed of a propeller shaft of the vehicle) of for example 100 rpm or less.
The present method comprises a step of, based on a predicted future driver-initiated demand forbrake torque from the hydraulic auxiliary brake arrangement, activating the pump so as to transfer hydraulic fluid from the reservoir to the hydraulic circuit.
The prediction of a future driver-initiated demand for brake torque from the hydraulic auxiliary brakearrangement may for example be made based on current travelling speed of the vehicle, the currentvehicle load and map data. Based on the map data, a future vehicle speed at a certain point in timeor a future vehicle speed profile may be estimated. The current vehicle speed may be determined byvarious means as known in the art. For example, the rotational speed of the driven wheels may beused. Alternatively, the rotational speed of the second shaft (on which the hydraulic auxiliary brakearrangement is configured to exert a braking torque when activated) may be used. A rotationalspeed of other shafts of the vehicle powertrain may also be used for determining the vehicle speed,based on the knowledge of the configuration of the vehicle powertrain. A person skilled in the art iswell aware of the interrelation between a traveling speed of the vehicle and the rotational speed of various shafts, and this will therefore not be described further in the present disclosure.
The present method is primarily intended for a hydraulic auxiliary brake arrangement in which thepump is driven by the rotation of the first shaft. ln such a case, the pump is not able to transferhydraulic fluid to the hydraulic circuit in case the first shaft is in a non-rotating state. This also means than any potential leakage from the hydraulic circuit will increase the time it would take to fill up the hydraulic circuit when the hydraulic auxiliary brake is to be activated so as to exert a braking torque.The first shaft may be in a non-rotating state when the first shaft is disconnected from the secondshaft of the vehicle powertrain. ln case the pump is driven by rotation of the first shaft, the step ofactivating the pump may be performed by connecting the first shaft with the second shaft of thevehicle powertrain. Thereby, the first shaft will start to rotate with a rotationa| speed proportiona| tothe rotationa| speed of the second shaft of the vehicle powertrain. This in turn causes the pump totransfer hydraulic fluid from the reservoir into the hydraulic circuit. lt is however also plausible thatan electric pump is used instead of a pump driven by the rotation of the first shaft. ln such a case, theactivation of the pump may be performed independently of whether the first shaft is connected to the second shaft or not.
The method further comprises a step of, when the pump has been activated, controlling the controlvalve so that a hydraulic pressure in the hydraulic circuit is lower than a preselected threshold value.Said control of the control valve is performed at a point in time prior to the point in time of thepredicted driver-initiate demand for a brake torque from the hydraulic auxiliary brake arrangement.The purpose of controlling the hydraulic pressure to lower than the preselected threshold value is tominimize the risk of unintentionally causing an undesirable braking torque from the hydraulicauxiliary brake arrangement before a demand therefore has been issued. The preselected thresholdvalue may for example correspond to a pressure value at which no braking torque is exerted by thehydraulic auxiliary brake arrangement. ln some instances, it may however also be desired that thehydraulic pressure is above a pressure at which the hydraulic auxiliary brake arrangement exerts abrake torque on the second shaft of the vehicle powertrain, since this may further reduce theactivation time of the hydraulic auxiliary brake arrangement upon a demand for brake torquetherefrom. ln case of the hydraulic pressure being sufficient to cause a brake torque from thehydraulic auxiliary brake arrangement, such a brake torque should however be sufficiently small soas to not su bstantially increase the fuel consumption of the vehicle. By way of example, the controlvalve may be configured to control the hydraulic pressure in the hydraulic circuit such that a brakingtorque of about 10 Nm or about 5 Nm is exerted by the hydraulic auxiliary brake arrangement on the second shaft. ln case the driver does not demand a braking torque from the hydraulic auxiliary brake arrangementas predicted, it is generally desirable to minimize the energy loss caused by the hydraulic auxiliarybrake arrangement for the purpose of saving fuel. Therefore, the method may further comprise astep of, based on a determination that the predicted future driver-initiated demand for brake torque from the hydraulic auxiliary brake arrangement was not demanded as predicted, disconnecting the hydraulic auxiliary brake arrangement from the second shaft of the vehicle powertrain.Disconnecting the hydraulic auxiliary brake arrangement from the second shaft may be performed by previously known methods therefore.
The performance of the method for controlling a hydraulic auxiliary brake arrangement as describedherein may be governed by programmed instructions. These programmed instructions typically takethe form of a computer program which, when executed in or by a control device, causes the controldevice to effect desired forms of control action. Such instructions may typically be stored on a computer-readable medium.
The present disclosure further relates to a control device to control a hydraulic auxiliary brakearrangement in accordance with the method described above. The control device may be configuredto perform any one of the steps of the method for controlling a hydraulic auxiliary brake arrangement of a vehicle powertrain as described herein.
More specifically, a control device configured to control a hydraulic auxiliary brake arrangement of avehicle powertrain is provided. The hydraulic auxiliary brake arrangement comprises a rotatable firstshaft connecta ble to a second shaft of the vehicle powertrain. The second shaft constitutes the shafton which the hydraulic auxiliary brake arrangement is intended to apply a braking torque whenactivated. The hyd raulic auxiliary brake arrangement further comprises a rotor, connected to the firstshaft, and a stator. The stator and the rotorjointly form a toroidal volume into which hydraulic fluidmay be introduced for the purpose of creating a braking effect. The hydraulic brake arrangementfurther comprises a hyd raulic circuit connected to the toroidal volume, a reservoir for hydraulic fluid,a pump configured to transfer hydraulic fluid from the reservoir to the hydraulic circuit, as well as acontrol valve configured to control the hydraulic pressure in the hydraulic circuit. The control deviceis configured to, based on a predicted future driver-initiated demand for brake torque from thehydraulic auxiliary brake arrangement, activate the pump so as to transfer hydraulic fluid from thereservoir to the hydraulic circuit. The control device is further configured to, when the pump hasbeen activated, control the control valve so that a hydraulic pressure in the hydraulic circuit is lower that a preselected threshold value.
The present disclosure further relates to a vehicle comprising a vehicle powertrain. The vehiclepowertrain further comprises a hydraulic auxiliary brake arrangement, and the control device as described above.
Figure 1 schematically illustrates a side view of an example of a vehicle 1. The vehicle 1 comprises apowertrain 2 comprising an internal combustion engine 3 and a gearbox 4. A clutch (not shown) maybe arranged between the internal combustion engine 3 and the gearbox 4. The gearbox 4 isconnected to the driving wheels 7 of the vehicle 1 via an output shaft 6 of the gearbox 4. The vehicle1 may further comprise a hydraulic auxiliary brake arrangement. The hydraulic auxiliary brakearrangement may for example be a retarder 8 connected to the output shaft 6 of the gearbox, or a pretarder 9 connected to the crankshaft of the internal combustion engine 3.
Figure 2 schematically illustrates an exemplifying embodiment of a hydraulic auxiliary brakearrangement, here in the form of a retarder 8. The retarder 8 comprises a rotatable first shaft 20,which may also be called a retarder shaft. The retarder shaft 20 is connecta ble to a shaft 24 of thevehicle powertrain, such as the output shaft of a gearbox, via a pair of cogwheels 21, 22. The firstcogwheel 21 is arranged on the retarder shaft 20, and the second cogwheel 22 is connecta ble to theshaft 24 of the vehicle powertrain. ln order to be able to connect and disconnect the retarder 8 fromthe vehicle powertrain, the cogwheel 22 may be provided with a synchromesh arrangement 25 orany other type of clutch device. When the retarder 8 is connected to the shaft 24 of the vehiclepowertrain, the retarder 8 may provide a braking torque to the shaft 24. The retarder shaft 20 may be journaled via a bearing 26 in for example a housing of a gearbox of the vehicle powertrain.
The retarder 8 comprises a rotor 30 connected to the retarder shaft 20, for example by mutuallyengaging splines. The rotor 30 therefore rotates together with the retarder shaft 20. Thus, when theretarder 8 is connected to the vehicle powertrain, the rotor 30 will rotate with a rotational speedproportional to the rotational speed of the shaft 24 of the vehicle powertrain, subject to a possiblegear ratio between the cogwheels 21, 22. The retarder further comprises a stator 32 formed by orconnected to a housing 28 of the retarder. The stator 32 is thus not able to rotate. The retarder 8further comprises a pump 34, which typically is driven by the retarder shaft 20. The pump 34 may for example be radially governed by the retarder shaft 20.
The retarder housing further comprises a reservoir 36 for hydraulic fluid, the hydraulic fluid typically being oil. A filter 38 may be provided to filter out potential particular matter from the hydraulic fluid.
The rotor 30 and the stator 32 jointly form a toroidal volume 33, which may be referred to as a torus.This toroidal volume 33 constitutes a cavity into which hydraulic fluid may be introduced when abraking torque is desired. ln other words, when a braking torque is to be exerted on the shaft 24 of the vehicle powertrain by means of the retarder 8, hydraulic fluid is introduced into the toroidal 11 volume 33. The traveling speed of the vehicle will thus be reduced as a result of the braking torqueexerted on the shaft 24. The braking effect arises since the rotor 30 and the stator 32 are equippedwith blades (not shown), which create a flow of the hydraulic fluid in the toroidal volume when therotor 30 rotates. The blades may be inclined with a certain angle to the plane of rotation of the rotor .
More specifically, by forcing the hydraulic fluid into the toroidal volume 33 when the rotor 30 isrotating, the rotor throws the hydraulic fluid out against its internal outer diameter and thus into thestator 32. The stator uses the blades and its ring-shaped torus surface to return the hydraulic fluid tothe rotor 30, but in this case to its internal inner diameter. The rotor therefore receives the hydraulicfluid axially at its internal inner diameter and flings the hydraulic fluid axially at the internal outsidediameter but in the opposite direction. This recombination of the hydraulic fluid means that the rotoris exposed to an axial force. The hydraulic fluid is then sent on between the stator and the rotor inthe direction of the blades, which means that a radial force is also applied because of therecombination of the hydraulic fluid. This is the force providing the brake torque on the rotor 8 andthus the reta rder shaft 20. This flow of hydraulic fluid creates a reaction force, which forms thebraking effect. This means that the greater the speed of the hydraulic fluid, the greater the reaction force and thus the braking torque.
When the retarder 8 no longer should provide a braking torque to the shaft 24 of the vehiclepowertrain, the toroidal volume 33 is drained of the hydraulic fluid, which entails that that the bladeswill instead create an air flow in the toroidal volume. This air flow may create an undesirable reactionforce on the retarder shaft 20, and thereby an undesired braking torque on the shaft 24. Theundesired braking torque caused by the air flow is small, considerably lower than a braking torquecaused by the hydraulic fluid. However, it may still lead to a small braking effect on the vehicle whichtherefore needs to be compensated by the driving torque provided by the combustion engine. This inturn leads to an increase in the fuel consumption. The friction of bearings, and the pump 34 whendriven by the retarder shaft 20, also exert a reaction force which causes an increased fuelconsumption. For said reason, it may be desired to disconnect the retarder 8 from the shaft 24 whenthe retarder 8 is not intended to brake the vehicle. This may be achieved by disconnecting the cogwheel 22 from the shaft 24.
Filling and draining of the toroidal volume 33 take place by means of a hydraulic circuit 40. Thehydraulic circuit 40 comprises a primary circuit 40a and a secondary circuit 40b. When the retarder 8 is activated in order to brake the vehicle, the cogwheel 20 is connected to the shaft 24. Thereby, the 12 retarder shaft 20 rotates, which in turn may drive the pump 34. The pump 34 thereby pumpshydraulic fluid through the hydraulic circuit 40. More specifically, the pump 34 pumps hydraulic fluidfrom the reservoir 36 via the filter 38 and fills the primary circuit 40a with hydraulic fluid. Theprimary circuit is connected with the toroidal volume 33. Thereby, the toroidal volume 33 may befilled with hydraulic fluid such that the retarder can provide the intended braking torque. A safetyvalve 42 is closed when hydraulic fluid should be introduced into the toroidal volume 33 to providethe braking effect. The safety valve 42 functions as a drainage valve which opens and closes adrainage channel 43 allowing drainage of hydraulic fluid from the toroidal volume 33 to the reservoir36. The safety valve 42 may be closed by hydraulic fluid, added via a first regulation valve that may be arranged for example in a valve arrangement 45.
When the retarder 8 is used to brake the vehicle, and the toroidal volume 33 thus is filled withhydraulic fluid, the hydraulic fluid will be heated by the flow effects generated in the toroidal volume33. This is because the high speed of the hydraulic fluid causes friction against the surfaces of theblades, rotor and stator. ln other words, the mechanical effect is converted into thermal effect in theform of heating of the hydraulic fluid. The hydraulic fluid therefore needs to be cooled. This isachieved by the hydraulic fluid being led through the secondary circuit 40b of the hydraulic circuit 40to a cooler 48. The hydraulic fluid is led from the cooler 48 further through the secondary circuit 40bwhich is, downstream of the cooler 48, connected to the toroidal volume 33. Thus, the secondarycircuit may return the hydraulic fluid to the toroidal volume 33. Downstream of the cooler 48, thesecondary circuit 40b is connected with the reservoir 36 via a control valve 50. The control valve 50may be opened and closed by hydraulic fluid via a proportional valve arranged in the valvearrangement 45. The control valve 50 is also used to control the pressure in the retarder and thus thebraking torque provided by the retarder. When the retarder 8 is used to brake the vehicle, thecontrol valve 50 is at least partly closed. Thus, the hydraulic fluid in the secondary circuit 40b will be returned to the toroidal volume 33.
When the retarder should no longer brake the vehicle, the toroidal volume 33 needs to be drainedfrom the hydraulic fluid. This is achieved by opening the safety valve 42 and the control valve 50.Thereby, the hydraulic fluid leaves the toroidal volume 33 via the drainage channel 43 and via a channel 51 of the control valve 50.
A check valve 52 may be provided at an outlet of the toroidal volume 33. When the retarder is not intended to provide a braking effect, the check valve 52 is closed. Thereby, hydraulic fluid may flow 13 to the cooler 48 and further through the secondary circuit onto a corresponding check valve 53 arranged at the inlet of the toroidal volume.
When the retarder 8 is to be activated so as to be able to provide the intended braking torque to theshaft 24 of the vehicle powertrain, the hydraulic circuit 40 has to be filled as quickly as possible. lncase the retarder 8 has been disconnected from the shaft 24 before activation, the pump 34 hasbeen at standstill and hydraulic fluid may have leaked out from the hydraulic circuit. Thereby, theactivation time of the retarder may be quite su bstantial which in turn may lead to safety risks and theneed to use the service brakes of the vehicle. This in turn leads to excessive wear of the servicebrakes. To reduce the activation time of the retarder, the retarder 8 may therefore comprise anaccumulator 46, connected to the toroidal volume 33, which may assist in the filling of the hydrauliccircuit 40. The accumulator 46 may be pre-filled with hydraulic fluid from the reservoir, and may forits operation be controlled by a second regulation valve that may be arranged for example in thevalve arrangement 45. The accumulator 46 is used for forcing an additional quantity of hydraulic fluidinto the hydraulic circuit when the retarder is to be activated and the retarder 8 is connected to the shaft 24.
The constituent components of the retarder may be controlled by a control device 100 configuredtherefore. The control device 100 may be a part of the retarder as such, but may also be any othercontrol device of the vehicle powertrain. The control device 100 may comprise one or more controlunits. ln case of the control device comprising a plurality of control units, each control unit may beconfigured to control a certain function or a certain function may be divided between more than one control units.
The accumulator 46 works very well in many situations to reduce the activation time of the retarder8. However, problems may arise in case the accumulator is not able to provide the intendedadditional quantity of hydraulic fluid, for example due to leakage of hydraulic fluid, or is not presentat all. ln these situations, the time it takes until the retarder 8 provides the intended braking torqueto the shaft 24 may be so long that the vehicle acceleration may be unacceptable. This may in turnresult in a need to activate the service brakes, which in turn leads to increased wear thereof. Theproblem of long activation time of the retarder may be even worse in case the retarder has beendisengaged from the shaft 24 of the vehicle powertrain for some time, since this also means that thepump 34 is not pumping any hydraulic fluid into the hydraulic circuit and hydraulic fluid thus may have leaked out of the hydraulic circuit into the reservoir in a greater quantity than intended. 14 ln case a cruise control is used for the vehicle, the cruise control may to some extent be configuredto take into account the activation time of the retarder 8. However, in case a driver desires toactivate the retarder, the time delay until the retarder provides the desired braking torque maycause serious safety risks. The method and control device according to the present disclosureaddress this issue and results in a considerable reduction of the activation time of retarder when a driver of the vehicle demands a braking torque from the retarder. lt should be noted that although the above is described with reference to an oil retarder, a waterretarder may function in essentially the same way. The same functions and considerations asdescribed with reference to Figure 2 may thus apply also to a water retarder. The problem mayhowever be somewhat more pronounced for an oil retarder, since the temperature of the oil alsoaffects the viscosity of the hydraulic fluid, and therefore also the flow thereof into the hydraulic circuit.
Figure 3 represents a flowchart schematically illustrating one exemplifying em bodiment of a methodfor controlling a hydraulic auxiliary brake arrangement of a vehicle powertrain in accordance with thepresent disclosure. The method comprises a step of activating S101 the pump of the hydraulicauxiliary brake arrangement so as to transfer hydraulic fluid from the reservoir to the hydrauliccircuit. The activation of the pump is performed based in a predicted future driver-initiated demandfor brake torque from the hydraulic auxiliary brake arrangement. The method further comprises astep of controlling S102 the hydraulic pressure in the hydraulic circuit, by means of the control valve of the hydraulic auxiliary brake arrangement, to a pressure lower than a preselected threshold value.
Figure 4 schematically illustrates an exemplifying em bodiment 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.
The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/writememory 550. The non-volatile memory 520 has a first memory element 530 in which a computerprogram, e.g. an operating system, is stored for controlling the function of the device 500. The device500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, atime and date input and transfer unit, an event counter and an interruption controller (not depicted).
The non-volatile memory 520 has also a second memory element 540.
There is provided a computer program P that comprises instructions for controlling a hydraulicauxiliary brake arrangement, such as a retarder, of a vehicle powertrain. Said hydraulic brakearrangement comprises a rotatable first shaft connecta ble to a second shaft of the vehiclepowertrain. The hydraulic auxiliary brake arrangement further comprises a rotor, connected to thefirst shaft, and a stator, which together with the rotor forms a toroida| volume into which hydraulicf|uid may be introduced. The hydraulic brake arrangement further comprises a hydraulic circuitconnected to the toroida| volume, a reservoir for hydraulic f|uid, a pump configured to transferhydraulic f|uid from the reservoir to the hydraulic circuit, and a control valve configured to controlthe hydraulic pressure in the hydraulic circuit. The computer program comprises instructions for,based on a predicted future driver-initiated demand for brake torque from the hydraulic auxiliarybrake arrangement, activating the pump so as to transfer hydraulic f|uid from the reservoir to thehydraulic circuit. The computer program further comprises instructions for controlling the control valve so that a hydraulic pressure in the hydraulic circuit is lower than a preselected threshold value.
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 one or more functions, i.e. the data processing unit 510may effect a certain part of the program P stored in the memory 560 or a certain part of the program P 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 is intended for communication with the data processing unit 510 via a data bus512. The separate memory 560 is intended to communicate with the data processing unit 510 via adata bus 511. The read/write memory 550 is adapted to communicate with the data processing unit510 via a data bus 514. The communication between the constituent components may beimplemented by a communication link. A communication link may be a physical connection such asan optoelectronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link.
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 510 is prepared to effect code execution as described above. 16 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. A method for controlling a hydraulic auxiliary brake arrangement (8, 9) of a vehiclepowertrain (2), the method performed by a control device (100),the hydraulic auxiliary brake arrangement (8, 9) comprising:a rotata ble first shaft (20) connecta ble to a second shaft (24) of the vehiclepowertrain (2),a rotor (30) connected to the first shaft (20),a stator (32), which together with the rotor (30) forms a toroidal volume (33) intowhich hydraulic fluid may be introduced,a hydraulic circuit (40) connected to the toroidal volume (33),a reservoir (36) for hydraulic fluid,a pump (34) configured to transfer hydraulic fluid from the reservoir (36) to thehydraulic circuit (40), anda control valve (50) configured to control the hydraulic pressure in the hydrauliccircuit (40);the method comprising the steps of:based on a predicted future driver-initiated demand for brake torque from thehydraulic auxiliary brake arrangement, activating (S101) the pump (34) so as to transferhydraulic fluid from the reservoir (36) to the hydraulic circuit (40); andcontrolling (S102) the control valve (50) so that a hydraulic pressure in the hydraulic circuit is lower than a preselected threshold value.
2. The method according to claim 1, comprising a step of predicting a future driver-initiateddemand for brake torque from the hydraulic auxiliary brake arrangement based on vehicle speed, vehicle load and map data.
3. The method according to any one of the preceding claims, wherein the pump (34) is drivenby rotation of the first shaft (20), and wherein activating the pump (34) is performed byconnecting the first shaft (20) of the hydraulic auxiliary brake arrangement with the second shaft (24) of the vehicle powertrain so that the rotata ble first shaft starts to rotate.
4. The method according to any one of the preceding claims, wherein the step of controlling(S102) the control valve so that a hydraulic pressure in the hydraulic circuit (40) is lower than a preselected threshold value further comprises controlling the control valve (50) so that the 18 hydraulic pressure in the hydraulic circuit is above a pressure at which the hydraulic auxiliarybrake arrangement (8, 9) exerts a brake torque on the second shaft (24) of the vehicle powertrain. The method according to any one of the preceding claims, further comprising a step of:based on a determination that the predicted future driver-initiated demand for brake torque from the hydraulic auxiliary brake arrangement (8, 9) was not demanded as predicted, disconnecting the hydraulic auxiliary brake arrangement (8, 9) from the vehicle powertrain (2). The method according to any one of the preceding claims, wherein the hydraulic auxiliary brake arrangement (8) is a retarder. A computer program (P) comprising instructions which, when executed by a control device(100), cause the control device (100) to carry out 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 carry out the method according to any one of claims 1 to 6. A control device (100) configured to control a hydraulic auxiliary brake arrangement (8, 9) ofa vehicle powertrain (2),the hydraulic auxiliary brake arrangement (8, 9) comprising:a rotata ble first shaft (20), connectable to a second shaft (24) of the vehiclepowertrain,a rotor (30) connected to the first shaft (20),a stator (32), which together with the rotor (30) forms a toroidal volume (33) intowhich hydraulic fluid may be introduced,a hydraulic circuit (40) connected to the toroidal volume (33),a reservoir (36) for hydraulic fluid,a pump (34) configured to transfer hydraulic fluid from the reservoir (36) to thehydraulic circuit (40), anda control valve (50) configured to control the hydraulic pressure in the hydraulic circuit (40), wherein the control device (100) is configured to, based on a predicted future driver-initiated demand for brake torque from the hydraulic auxiliary brake arrangement (8, 9),activate the pump (34) so as to transfer hydraulic fluid from the reservoir (36) to thehydraulic circuit (40), the control device (100) further configured to, when the pump (34) has beenactivated, control the control valve (50) so that a hydraulic pressure in the hydraulic circuit (40) is lower that a preselected threshold value. The control device (100) according to claim 9, further configured to predict the future driver-initiated demand for brake torque from the hydraulic auxiliary brake arrangement (8, 9) based on vehicle speed, vehicle load and map data. The control device (100) according to any one of claims 9 or 10, wherein the pump (34) isdriven by rotation of the first shaft (20), and wherein the control device (100) is configured toactive the pump (34) by connecting the first shaft of the hydraulic auxiliary brakearrangement with the second shaft of the vehicle powertrain so that the first shaft (20) starts tO rOtate. The control device (100) according to any one of claims 9 to 11, further configured to controlthe control valve (50) so that the hydraulic pressure in the hydraulic circuit (40) is above apressure at which the hydraulic auxiliary brake arrangement (8, 9) exerts a preselected braketorque on the second shaft (24) of the vehicle powertrain at a point in time prior to the pointin time of the predicted future driver-initiated demand for brake torque from the auxiliary brake arrangement (8, 9). The control device (100) according to any one of claims 9 to 12, further configured todisconnect the first shaft of the hydraulic auxiliary brake arrangement (8, 9) from the secondshaft of the vehicle powertrain (2) based on a determination that the predicted future driver-initiated demand for brake torque from the hydraulic auxiliary brake arrangement was not demanded as predicted. A vehicle (1) comprising a hydraulic auxiliary brake arrangement (8, 9) and the control device (100) according to any one of claims 9 to 13.
SE2050990A 2020-08-27 2020-08-27 Control device and method for controlling a hydraulic auxiliary brake arrangement SE544474C2 (en)

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DE102021121205.7A DE102021121205A1 (en) 2020-08-27 2021-08-16 Control device and method for controlling a hydraulic auxiliary brake assembly

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US20090306871A1 (en) * 2005-06-09 2009-12-10 Nicholas Alford Compensation of reduced braking effect of a hydraulic brake system for a land craft
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EP3000675A1 (en) * 2014-09-11 2016-03-30 Scania CV AB Method and system to control a disengageable retarder
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SE1850884A1 (en) * 2018-07-11 2020-01-12 Scania Cv Ab A method and an apparatus for controlling a motor vehicle

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1302380A2 (en) * 2001-09-14 2003-04-16 Zf Friedrichshafen Ag Hydrodynamic retarder and method of operating a vehicle hydrodynamic retarder
US20090306871A1 (en) * 2005-06-09 2009-12-10 Nicholas Alford Compensation of reduced braking effect of a hydraulic brake system for a land craft
DE102012007732A1 (en) * 2012-04-18 2013-10-24 Daimler Ag Drive train for motor vehicle, has retarder that is connected with synchronizing unit to output shaft of gearbox over switching element, where sensor unit is provided to generate sensor signal provided for actuation of filling unit
WO2014062111A1 (en) * 2012-10-17 2014-04-24 Scania Cv Ab Retarder for braking a motive power source, vehicle comprising a retarder and method for engaging and disengaging a retarder
DE102015205851A1 (en) * 2014-05-08 2015-11-12 Voith Patent Gmbh Powertrain with switchable hydrodynamic machine
WO2015197092A1 (en) * 2014-06-27 2015-12-30 Volvo Truck Corporation An arrangement and method for a cruise control brake in a vehicle
EP3000675A1 (en) * 2014-09-11 2016-03-30 Scania CV AB Method and system to control a disengageable retarder
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US20200001844A1 (en) * 2017-03-06 2020-01-02 Voith Patent Gmbh Method for controlling a separating clutch
SE1850884A1 (en) * 2018-07-11 2020-01-12 Scania Cv Ab A method and an apparatus for controlling a motor vehicle

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