SE543135C2

SE543135C2 - Retarder arrangement and method

Info

Publication number: SE543135C2
Application number: SE1851151A
Authority: SE
Inventors: Mikael Sannelius
Original assignee: Scania Cv Ab
Priority date: 2018-09-27
Filing date: 2018-09-27
Publication date: 2020-10-13
Also published as: DE112019004132T5; WO2020067955A1; SE1851151A1

Abstract

A hydrodynamic retarder (1) is disclosed configured to brake a shaft (3) of a vehicle (5). The retarder (1) comprises a working circuit (9, 15, 19) comprising a shovel space (9), a workspace (15), and an outlet channel (19). Moreover, the retarder (1) comprises a pressure sensor arrangement (21) configured to, at least selectively, sense the pressure at a first portion (23) of the working circuit (9, 15, 19) and at a second portion (25) of the working circuit (9, 15, 19), wherein the second portion (25) is different from the first portion (23). The present disclosure further relates to a retarder arrangement (40), a transmission arrangement (50), a power train (60), a vehicle (5), a method (100) of estimating a braking torque of a retarder (1), a computer program, a computer-readable medium (200), and a control arrangement (43) for a retarder (1).

Description

Retarder arrangement and method TECHNICAL FIELD The present disclosure relates to hydrodynamic retarder configured to brake a shaft of avehicle. The present disclosure further relates to a retarder arrangement, a transmissionarrangement, a power train, a control arrangement, and a vehicle. Moreover, the presentdisclosure relates to a method of estimating a braking torque of a retarder, a computer program, and a computer-readable medium.

BACKGROUND Retarders are devices used on vehicles to augment or replace some of the functions ofprimary braking arrangements, such as friction-based braking arrangements. One commontype of retarder is hydrodynamic retarders. Such retarders utilize the viscous drag forces of aliquid in a work space between a rotor and a stator. The rotor is usually connected to a shaftof the vehicle, such as a shaft of the gearbox of the vehicle, via a retarder transmission.Traditionally, the work space has been emptied of liquid when the retarder is not in use. lngeneral, due to environmental concerns, it is an advantage if vehicle arrangements, such asretarder arrangements, have low parasitic losses when not in use. As a reason thereof, someretarders utilize coupling devices to mechanically disconnect the rotor of the retarder from a driving shaft in order to minimize parasitic losses.

Retarders are capable of providing several advantages. As an example, they are less likelyto become over heated in comparison to friction-based braking arrangements, for examplewhen braking a vehicle travelling downhill. Furthermore, when used, retarders lower wear of primary friction-based braking arrangements.

The braking torque of a hydrodynamic retarder is difficult to estimate. During braking, thepressure inside a hydrodynamic retarder can be very high and can vary to a great extent.Moreover, in some portions of the hydrodynamic retarder, and in some braking torqueranges, the pressure can reach levels close to vaporization. However, a good estimation ofthe retarder braking torque can be vital for achieving control functions such as for example asmooth brake blending with other braking systems, an exact control of the braking torque,and the like. Furthermore, in retarders comprising a coupling device used to mechanicallydisconnect the rotor from a driving shaft, a proper estimation of the retarder braking torquecan be important for providing a confirmation of whether the rotor is connected to a driving shaft or not. 2 ln addition, generally, on today's consumer market, it is an advantage if products, such asvehicle arrangements, comprise different features and functions while the products haveconditions and/or characteristics suitable for being manufactured and assembled in a cost- efficient manner.

SUMMARYlt is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by a retarder arrangementcomprising a hydrodynamic retarder configured to brake a shaft of a vehicle. The retardercomprises a retarder housing with a shovel space and a shovel arrangement arranged in theshovel space. The shovel arrangement comprises a shovel-equipped stator and a shovel-equipped rotor together forming a workspace. The retarder further comprises an inletchannel and an outlet channel arranged to supply and evacuate, respectively, working fluidto and from the workspace. Further, the retarder comprises a working circuit comprising theshovel space, the workspace, and the outlet channel. The retarder further comprises apressure sensor arrangement configured to, at least selectively, sense the pressure at a firstportion of the working circuit, and at a second portion of the working circuit, wherein thesecond portion is different from the first portion. The retarder arrangement comprises acontrol arrangement. The control arrangement is connected to the pressure sensorarrangement and is configured to estimate a braking torgue of the retarder based on sensedpressure at the first portion of the working circuit, in a first braking torgue range, and toestimate the braking torgue of the retarder based on sensed pressure at the second portionof the working circuit in a second braking torgue range. Therebv, a retarder arrangement isprovided capable of performing an improved estimation of a current braking torgue of theretarder over a wider braking torgue range. As a result, a retarder arrangement is providedhaving conditions for a more precise control of the braking torgue of the retarder. Moreover,a retarder arrangement is provided having conditions for obtaining a smoother brakeblending between the retarder and other braking svstems. ln addition, a retarderarrangement is provided having conditions for performing a better estimation of whether the rotor is connected to a driving shaft or not.

Since the retarder comprises the pressure sensor arrangement configured to, at leastselectively, sense the pressure at the first and second portions of the working circuit, a retarder is provided having conditions for an improved estimation of a current braking torgue 3 of the retarder. Moreover, conditions are provided for an improved estimation of a currentbraking torque of the retarder over a wider braking torque range. This because the optimalportion of the working circuit for sensing the pressure varies with the braking torque level.Therefore, by sensing the pressure at the first and second portions of the working circuit, animproved estimation of a current braking torque can be made over a wider braking torque range.

Since conditions are provided for an improved estimation of a current braking torque of theretarder over a wider braking torque range, conditions are also provided for a more precisecontrol of the braking torque of the retarder. Moreover, conditions are provided for asmoother brake blending between the retarder and other braking systems. ln addition,conditions are provided for a better estimation of whether the rotor is connected to a driving shaft or not.

Accordingly, a retarder arrangement is provided overcoming, or at least alleviating, at leastsome of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the first portion of the working circuit is a portion of the outlet channel. Thereby,conditions are provided for an improved estimation of the braking torque at low brakingtorque levels. This because the pressure at the outlet channel is optimal as a base for anestimation of the braking torque at low braking torque levels. Moreover, since conditions areprovided for an improved estimation of the braking torque at low braking torque levels, areliable confirmation can be obtained of whether the rotor is connected to a driving shaft or not.

Optionally, the second portion of the working circuit is a portion of the shovel space. Thereby,conditions are provided for an improved estimation of the braking torque at high brakingtorque levels. This because the pressure in the shovel space is indicative of the brakingtorque at higher braking torque levels. Conversely, at lower braking torque levels, thepressure in the shovel space can reach levels close to vaporization. Since conditions areprovided for an improved estimation of the braking torque at higher braking torque levels, amore precise control of the braking torque of the retarder can be made. Moreover, a smoother brake blending between the retarder and other braking systems can be made.

Optionally, the pressure sensor arrangement comprises a first pressure sensor fluidly connected to the first portion of the working circuit, and a second pressure sensor fluidly 4 connected to the second portion of the working circuit. Thereby, a simple and reliableretarder is provided having conditions for an improved estimation of a current braking torque of the retarder over a wider braking torque range.

Optionally, the pressure sensor arrangement comprises one pressor sensor only. Thereby, asimple and cost-efficient retarder is provided having conditions for an improved estimation of a current braking torque of the retarder over a wider braking torque range.

Optionally, the retarder comprises a valve fluidly connected to the first and second portionsof the working circuit and to the pressure sensor, and wherein the valve comprises a firststate in which the valve opens a fluid connection between the pressure sensor and the firstportion and closes a fluid connection between the pressure sensor and the second portion,and a second state in which the valve opens the fluid connection between the pressuresensor and the second portion and closes the fluid connection between the pressure sensorand the first portion. Thereby, the pressure sensor can be brought into fluid communicationwith the first portion or the second portion of the working circuit simply by switching the valvebetween the first and second states. ln this manner, the pressure can be sensed at the firstportion or the second portion of the working circuit in dependence of the braking torque level,to provide an improved estimation of a current braking torque of the retarder over a wider braking torque range.

Optionally, the valve is arranged to switch between the first and second states based on apressure level supplied from a pressure source. Thereby, a simple and efficient control of the state of the valve can be performed.

Optionally, the pressure source is one of the first and second portions of the working circuit.Thereby, the valve can be switched between the first and second states in dependence ofthe pressure at one of the first and second portions of the working circuit. ln this manner, anautomatic control of the state of the valve can be performed based on a braking torque levelof the retarder. As a result, the need for additional control systems for controlling the valve between the first and second states is circumvented.

Optionally, the pressure source is the second portion of the working circuit, and wherein thevalve is configured to switch from the first state to the second state when the pressure at thesecond portion reaches above a predetermined pressure level. The fact that the pressure atthe second portion reaches above the predetermined pressure level indicates that the braking torque rises. Since the valve is configured to switch from the first state to the second state when the pressure at the second portion reaches above the predetermined pressurelevel, the valve will fluidly connect the pressure sensor to the second portion of the workingcircuit in an automatic manner when the braking torque rises. Thereby, an automatic controlof the state valve is performed in dependence of the braking torque, and an improved estimation of the braking torque at higher braking torque levels can be made.

Optionally, the valve is configured to switch from the second state to the first state when thepressure at the second portion drops below the predetermined pressure level. The fact thatthe pressure at the second portion drops below the predetermined pressure level indicatesthat the braking torque decreases. Since the valve is configured to switch from the secondstate to the first state when the pressure at the second portion drops below thepredetermined pressure level, the valve will fluidly connect the pressure sensor to the firstportion of the working circuit in an automatic manner when the braking torque decreases.Thereby, an automatic control of the state valve is performed in dependence of the brakingtorque, and an improved estimation of the braking torque at lower braking torque levels can be made.

According to a third-second aspect of the invention, the object is achieved by a transmission arrangement configured to transmit power between a power source of a vehicle and wheelsof a vehicle. The transmission arrangement comprises a retarder arrangement according tosome embodiments of the present disclosure. The retarder is configured to brake a shaft of the transmission arrangement. Thereby, a transmission arrangement is provided having 6 conditions for an improved estimation of a current braking torque of the retarder thereof overa wider braking torque range. As a result, a transmission arrangement is provided havingconditions for a more precise control of the braking torque of the retarder. Moreover, atransmission arrangement is provided having conditions for obtaining a smoother brakeblending between the retarder and other braking systems. ln addition, a transmissionarrangement is provided having conditions for performing a better estimation of whether the rotor of the retarder is connected to the shaft of the transmission arrangement or not.

According to a feu-Fth-ïaspect of the invention, the object is achieved by a power train fora vehicle, wherein the power train comprises a power source and a transmissionarrangement. The transmission arrangement is configured to transmit power between thepower source and wheels of the vehicle. The power train comprises a retarder arrangmentaccording to some embodiments of the present disclosure. The retarder is configured tobrake a shaft of the power train. Thereby, a power train is provided having conditions for animproved estimation of a current braking torque of the retarder thereof over a wider brakingtorque range. As a result, a power train is provided having conditions for a more precisecontrol of the braking torque of the retarder. Moreover, a power train is provided havingconditions for obtaining a smoother brake blending between the retarder and other brakingsystems. ln addition, a power train is provided having conditions for performing a betterestimation of whether the rotor of the retarder is connected to the shaft of the power train or not.

According to a fifth-maspect of the invention, the object is achieved by a vehiclecomprising a power train according to some embodiments of the present disclosure.Thereby, a vehicle is provided having conditions for an improved estimation of a currentbraking torque of the retarder thereof over a wider braking torque range. As a result, avehicle is provided having conditions for a more precise control of the braking torque of theretarder. Moreover, a vehicle is provided having conditions for obtaining a smoother brakeblending between the retarder and other braking systems of the vehicle. ln addition, a vehicleis provided having conditions for performing a better estimation of whether the rotor of the retarder is connected to the shaft of the vehicle or not.

According to a siaeth-fifth aspect of the invention, the object is achieved by a method ofestimating a braking torque of a retarder, wherein the retarder comprises:- a retarder housing with a shovel space, - a shovel arrangement arranged in the shovel space, 7 wherein the shovel arrangement comprises a shovel-equipped stator and ashovel-equipped rotor together forming a workspace, - an inlet channel and an outlet channel, arranged to supply and evacuate,respectively, working fluid to and from the workspace, - a working circuit comprising the shovel space, the workspace, and the outletchanneL - a pressure sensor arrangement, and - a control arrangement connected to the pressure sensor arrangement, wherein the method comprises: - estimating the braking torque based on sensed pressure at a first portion of theworking circuit in a first braking torque range, and - estimating the braking torque based on sensed pressure at a second portion ofthe working circuit in a second braking torque range, wherein the second portion is different from the first portion.

Thereby, a method is provided capable of estimating the current braking torque of theretarder with improved accuracy over a wider braking torque range. Moreover, the methodprovides conditions for a more precise control of the braking torque of the retarder andconditions for a smoother brake blending between the retarder and other braking systems. lnaddition, the method provides conditions for a better estimation of Whether the rotor is connected to a driving shaft or not.

Accordingly, a method is provided overcoming, or at least alleviating, at least some of theabove-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a seventh-maspect of the invention, the object is achieved by a computerprogram comprising instructions which, when the program is executed by a computer, causethe computer to carry out the method according to some embodiments of the presentdisclosure. Since the computer program comprises instructions which, when the program isexecuted by a computer, cause the computer to carry out the method according to someembodiments, a computer program is provided which provides conditions for overcoming, or at least alleviating, at least some of the above-mentioned drawbacks.

According to an eighth-seventh aspect of the invention, the object is achieved by a computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to some embodiments of the present disclosure. 8 Since the computer-readable medium comprises instructions which, when the program isexecuted by a computer, cause the computer to carry out the method according to someembodiments, a computer-readable medium is provided which provides conditions for overcoming, or at least alleviating, at least some of the above-mentioned drawbacks.

According to a ninth-e_igh_taspect of the invention, the object is achieved by a control arrangement for a retarder, Wherein the retarder comprises: - a retarder housing with a shovel space, - a shovel arrangement arranged in the shovel space,wherein the shovel arrangement comprises a shovel-equipped stator, and ashovel-equipped rotor together forming a workspace, - an inlet channel and an outlet channel, arranged to supply and evacuate,respectively, working fluid to and from the workspace, - a working circuit comprising the shovel space, the workspace, and the outletchannel, and - a pressure sensor arrangement, wherein the control arrangement is configured to: - estimate the braking torque based on sensed pressure at a first portion of theworking circuit in a first braking torque range, and - estimate the braking torque based on sensed pressure at a second portion ofthe working circuit in a second braking torque range, wherein the second portion is different from the first portion.

Thereby, a control arrangement is provided capable of estimating the current braking torqueof the retarder with improved accuracy over a wider braking torque range. Moreover, thecontrol arrangement provides conditions for a more precise control of the braking torque ofthe retarder and conditions for a smoother brake blending bet\Neen the retarder and otherbraking systems. ln addition, the control arrangement provides conditions for a better estimation of Whether the rotor is connected to a driving shaft or not.

Accordingly, a control arrangement is provided overcoming, or at least alleviating, at leastsome of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Further features of, and advantages With, the present invention Will become apparent When studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGSVarious aspects of the invention, including its particular features and advantages, will bereadily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which: Fig. 1 schematically illustrates a cross section of a hydrodynamic retarder, according to someembodiments, Fig. 2 schematically illustrates a cross section of a hydrodynamic retarder, according to somefurther embodiments, Fig. 3 schematically illustrates a power train, according to some embodiments, Fig. 4 illustrates a vehicle, according to some embodiments, Fig. 5 illustrates a method of estimating a braking torque of a retarder, according to someembodiments, and Fig. 6 illustrates computer-readable medium, according to some embodiments.

DETAILED DESCRIPTIONAspects of the present invention Will now be described more fully. Like numbers refer to likeelements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 schematically illustrates a cross section of a hydrodynamic retarder 1 according tosome embodiments. The hydrodynamic retarder 1 is configured to brake a shaft 3 of avehicle. As is further explained herein, according to the illustrated embodiments, thehydrodynamic retarder 1 is configured to brake a shaft 3 of a gearbox of a vehicle. For thereason of brevity and clarity, the hydrodynamic retarder 1 is in some places herein referred toas the retarder 1. The retarder 1 comprises a retarder housing 7 with a shovel space 9 and ashovel arrangement 11, 13 arranged in the shovel space 9. The shovel arrangement 11, 13comprises a shovel-equipped stator 11 and a shovel-equipped rotor 13 together forming aworkspace 15. The workspace 15 can also be referred to as a torus. The retarder 1 furthercomprises an inlet channel 17 and an outlet channel 19. The inlet channel 17 is arranged tosupply working fluid to the workspace 15. The outlet channel 19 is arranged to evacuateworking fluid from the workspace 15. The retarder 1 further comprises a Working circuit 9, 15, 19 comprising the shovel space 9, the workspace 15, and the outlet channel 19.

The retarder 1 comprises a retarder transmission 20 comprising a set of gear wheels 20',20”. Furthermore, the retarder 1 comprises a coupling device 22 and an actuator element 24 mechanically connected to the coupling device 22. The actuator element 24 is moveable between an actuated position and an unactuated position to move the coupling device 22between an engaged state and a disengaged state. The coupling device 22 is configured to,in the engaged state, connect the rotor 13 to the shaft 3 via the retarder transmission 20, and in the disengaged state, disconnect the rotor 13 from the shaft 3.

According to the illustrated embodiments, the retarder transmission 20 comprises a first gearwheel 20' and a second gear wheel 20”. The second gear wheel 20” is arranged on a rotorshaft 26 and the first gear wheel 20' is connectable to the shaft 3 by the coupling device 22.According to the illustrated embodiments, the coupling device 22 is configured to, in theengaged state, connect the first gear wheel 20' of the retarder transmission 20 to the shaft 3.Moreover, the coupling device 22 is configured to, in the disengaged state, disconnect thefirst gear Wheel 20' of the retarder transmission 20 from the shaft 3. Thus, according to theillustrated embodiments, the first gear wheel 20' and a second gear wheel 20” of the retardertransmission 20 Will not rotate, or Will at least not be driven by the shaft 3, When the couplingdevice 22 is in the disengaged state. The coupling device 22 may comprise a dog clutch, a synchronizer, or the like.

During operation of the retarder 1, i.e. during rotation of the rotor 13, the retarder 1 pumpsworking f|uid from the in|et channel 17 to the out|et channel 19, via the Workspace 15. Thein|et channel 17 and the out|et channel 19 may each comprise a p|ura|ity of parallel channelsarranged to supply and evacuate, respectively, working f|uid to and from the Workspace 15.As an example, the out|et channel 19, as referred to herein, may be integrated in the shovel-equipped stator 11 and may comprise one out|et channel portion per shovel of the shovel-equipped stator 11. According to such embodiments, the out|et channel portions may eachextend to a common ring-shaped volume arranged in the housing 7. The retarder 1comprises a brake valve 27 arranged to restrict flow of Working f|uid through the out|etchannel 19 so as to control the braking torque of the retarder 1. The Wording “out|et channel19” as used herein, may be defined as an out|et channel 19, or a set of out|et channels 19,extending from the Workspace 15 to the brake valve 27. From the brake valve 27, theworking medium flows through a retarder circuit 28, comprising a cooler 30, back to the in|et channel 17. The working medium may comprise oil or an aqueous mixture.

The retarder 1 comprises a pressure sensor arrangement 21. According to the embodimentsillustrated in Fig. 1, the pressure sensor arrangement 21 comprises a first pressure sensor31 fluidly connected to the first portion 23 of the Working circuit 9, 15, 19 and a secondpressure sensor 32 fluidly connected to the second portion 25 of the working circuit 9, 15, 19.

Moreover, according to the illustrated embodiments, the retarder 1 is comprised in a retarder 11 arrangement 40 comprising a control arrangement 43. The control arrangement 43 is connected to the first and second pressure sensors 31, 32.

According to the illustrated embodiments, the first portion 23 of the working circuit 9, 15, 19 isa portion of the outlet channel 19 upstream of the brake valve 27. Moreover, according to theillustrated embodiments, the second portion 25 of the working circuit 9, 15, 19 is a portion ofthe shovel space 9 adjacent to the rotor 13. According to further embodiments, the secondportion 25 of the working circuit 9, 15, 19 may be a portion of the workspace 15. Thepressure at the second portion 25 provides a reliable base for an estimation of the brakingtorque at higher braking torque levels. Conversely, at lower braking torque levels, thepressure at the second portion 25, i.e. at the shovel space 9, can reach levels close tovaporization and is not optimal as a base for an estimation of the braking torque at lower braking torque levels.

According to the illustrated embodiments, the control arrangement 43 is configured toestimate the braking torque based on sensed pressure at the first portion 23 of the workingcircuit 9, 15, 19 in a first braking torque range, and to estimate the braking torque based onsensed pressure at the second portion 25 of the working circuit 9, 15, 19 in a second brakingtorque range, wherein the first braking torque range is lower than the second braking torquerange. As a result, the control arrangement 43 can estimate the braking torque of theretarder 1, using values from the first pressure sensor 31, at low braking torque ranges withhigh accuracy, and can estimate the braking torque of the retarder 1, using values from thesecond pressure sensor 32, at higher braking torque ranges with high accuracy. ln thismanner, the control arrangement 43 is capable of estimating the current braking torque of theretarder 1 with improved accuracy over a wider braking torque range. Thereby, conditionsare provided for a more precise control of the braking torque of the retarder 1 and asmoother brake blending between the retarder 1 and other braking systems of a vehiclecomprising the retarder 1. ln addition, a better estimation can be made of whether the rotor 13 is connected to the shaft 3 or not.

According to some embodiments, the control arrangement 43 may estimate the brakingtorque of the retarder 1, using values from the first pressure sensor 31 when the pressure atthe second portion 25 is below a predetermined pressure level, and may estimate thebraking torque of the retarder 1, using values from the second pressure sensor 32 when thepressure at the second portion 25 is above the predetermined pressure level. Purely as anexample, the predetermined pressure level may be within the range of 0 - 3 bars, such as within the range of 0.1 - 3 bars. 12 According to further embodiments, the control arrangement 43 may be configured to utilizeinput from another arrangement or system as a basis for a determination of whether valuesfrom the first or second pressure sensor 31, 32 is to be used to estimate the braking torqueof the retarder 1. As an example, the control arrangement 43 may be configured to estimatethe braking torque of the retarder 1, using values from the first pressure sensor 31, duringidle rotation of the retarder 1. Moreover, the control arrangement 43 may be configured toestimate the braking torque of the retarder 1, using values from the first pressure sensor 31,when the actuator element 24 is in the unactuated position, to thereby confirm if the rotor 13is disconnected from the shaft 3. Furthermore, the control arrangement 43 may beconfigured to estimate the braking torque of the retarder 1, using values from the secondpressure sensor 32, during braking with the retarder 1. As an example, the controlarrangement 43 may be configured to estimate the braking torque of the retarder 1, usingvalues from the second pressure sensor 32, when the actuator element 24 is in the actuated position.

Fig. 2 schematically illustrates a cross section of a hydrodynamic retarder 1 according tosome further embodiments. The retarder 1 illustrated in Fig. 2 comprises the same features,functions, and advantages, as the retarder 1 illustrated in Fig. 1, with some exceptionsexplained below. According to the embodiments illustrated in Fig. 2, the pressure sensorarrangement 21 of the retarder 1 comprises one pressor sensor 35 only. The controlarrangement 43 is connected to the pressor sensor 35. Moreover, the retarder 1 comprises avalve 37 fluidly connected to the first and second portions 23, 25 of the working circuit 9, 15,19 and to the pressure sensor 35. The valve 37 comprises a first state in which the valve 37opens a fluid connection bet\Neen the pressure sensor 35 and the first portion 23 and closesa fluid connection between the pressure sensor 35 and the second portion 25. Furthermore,the valve 37 comprises a second state in which the valve 37 opens the fluid connectionbetween the pressure sensor 35 and the second portion 25 and closes the fluid connection between the pressure sensor 35 and the first portion 23.

According to the illustrated embodiments, the valve 37 is arranged to switch between the firstand second states based on a pressure level supplied from a pressure source 23, 25, 39,which, according to the illustrated embodiments, is the second portion 25 of the workingcircuit 9, 15, 19. The valve 37 is configured to switch from the first state to the second statewhen the pressure at the second portion 25 reaches above a predetermined pressure level.Moreover, the valve 37 is configured to switch from the second state to the first state when the pressure at the second portion 25 drops below the predetermined pressure level. Purely 13 as an example, the predetermined pressure level may be within the range of 1 - 3 bars. lnthis manner, an automatic control of the state of the valve 37 is obtained. All pressures andpressure levels given herein are pressures above atmospheric pressure, also referred to as gaUge DFGSSUFGS.

Thus, according to the illustrated embodiments, the pressure sensor 35 is fluidly connectedto the first portion 23 when the pressure at the second portion 25 is below the predeterminedpressure level. As a result, the control arrangement 43 can estimate the braking torque of theretarder 1, using sensed pressure at the first portion 23, at low braking torque ranges withhigh accuracy. ln addition, a better estimation can be made of whether the rotor 13 isconnected to the shaft 3 or not. At higher braking torque ranges, i.e. when the pressure atthe second portion 25 is above the predetermined pressure level, the pressure sensor 35 isfluidly connected to the second portion 25. As a result, the control arrangement 43 canestimate the braking torque of the retarder 1, using sensed pressure at the second portion25, at higher braking torque ranges with high accuracy. Thereby, conditions are provided fora more precise control of the braking torque of the retarder 1 and a smoother brake blendingbetween the retarder 1 and other braking systems of a vehicle comprising the retarder 1.Moreover, the control arrangement 43 is capable of estimating the current braking torque of the retarder 1 with improved accuracy over a wider braking torque range.

According to further embodiments, the valve 37 may be switched between the first andsecond states by an electronic control arrangement. Furthermore, according to someembodiments, the valve 37 is arranged to switch between the first and second states basedon a pressure level supplied from a pressure source 39 other than the first and secondportions 23, 25 of the working circuit 9, 15, 19, such as a control pressure from a vacuum generator, or the like.

Fig. 3 schematically illustrates a power train 60, according to some embodiments, for avehicle. The power train 60 comprises a power source 53 and a transmission arrangement50. The transmission arrangement 50 is configured to transmit power between the powersource 53 and wheels 55 of the vehicle. The power train 60 comprises a retarder 1, whichmay be a retarder 1 according to the embodiments illustrated in Fig. 1, or a retarder 1according to the embodiments illustrated in Fig. 2. The retarder 1 is configured to brake ashaft 3 of the power train 60. ln more detail, according to the illustrated embodiments, theretarder 1 is configured to brake a shaft 3 of the transmission arrangement 50, namely a shaft 3 of a gearbox 57 of the transmission arrangement 50. During braking, the torque 14 applied to the shaft 3 by the retarder 1 is transferred to the wheels 55 of the vehicle to provide a retardation force to the vehicle.

The power source 53 may comprise an internal combustion engine, for example acompression ignition engine, such as a diesel engine, or an Otto engine with a spark-ignitiondevice, wherein the Otto engine may be configured to run on gas, petrol, alcohol, similarvolatile fuels, or combinations thereof. As an alternative, or in addition, the power source 53 may comprise one or more electrical machines.

Fig. 4 illustrates a vehicle 5 according to some embodiments. The vehicle 5 comprises apower train 60 according to the embodiments illustrated in Fig. 3. The power train 60 is arranged to provide motive power to the vehicle 5 via wheels 55 of the vehicle 5.

According to the illustrated embodiments, the vehicle 5 is a truck. However, according tofurther embodiments, the vehicle 5, as referred to herein, may be another type of manned orunmanned vehicle for land based propulsion such as a lorry, a bus, a construction vehicle, a tractor, a car, or the like.

Fig. 5 illustrates a method 100 of estimating a braking torque of a retarder, according tosome embodiments. The retarder 1 may be a retarder 1 according to the embodimentsillustrated in Fig. 1, or a retarder1 according to the embodiments illustrated in Fig. 2.Therefore, below, reference is made to Fig. 5 as well as to Fig. 1 and Fig. 2. The method 100is a method 100 of estimating a braking torque of a retarder 1, wherein the retarder 1comprises:- a retarder housing 7 with a shovel space 9,- a shovel arrangement 11, 13 arranged in the shovel space 9,wherein the shovel arrangement 11, 13 comprises a shovel-equipped stator 11,and a shovel-equipped rotor 13, together forming a workspace 15,- an inlet channel 17 and an outlet channel 19, arranged to supply and evacuate,respectively, working fluid to and from the workspace 15,- a working circuit 9, 15, 19 comprising the shovel space 9, the workspace 15,and the outlet channel 19,- a pressure sensor arrangement 21, and- a control arrangement 43 connected to the pressure sensor arrangement 21,wherein the method 100 comprises:- estimating 110 the braking torque based on sensed pressure at a first portion 23 of the working circuit 9, 15, 19 in a first braking torque range, and - estimating 120 the braking torque based on sensed pressure at a secondportion 25 of the working circuit 9, 15, 19 in a second braking torque range, Wherein the second portion 25 is different from the first portion 23. lt will be appreciated that the various embodiments described for the method 100 are allcombinable With the control arrangement 43 as described herein. That is, the controlarrangement 43 may be configured to perform any one of the method steps 110, 120 of themethod 100.

Fig. 6 illustrates computer-readable medium 200 comprising instructions which, whenexecuted by a computer, cause the computer to carry out the method 100 according to some embodiments of the present disclosure.

According to some embodiments, the computer-readable medium 200 comprises a computerprogram comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method 100 according to some embodiments.

One skilled in the art Will appreciate that the method 100 of estimating a braking torque of aretarder 1 may be implemented by programmed instructions. These programmed instructionsare typically constituted by a computer program, Which, When it is executed in the controlarrangement 43, ensures that the control arrangement 43 carries out the desired control,such as the method steps 110 and 120 described herein. The computer program is usuallypart of a computer program product 200 which comprises a suitable digital storage medium on which the computer program is stored.

The control arrangement 43 may comprise a calculation unit Which may take the form ofsubstantially any suitable type of processor circuit or microcomputer, e.g. a circuit for digitalsignal processing (digital signal processor, DSP), a Central Processing Unit (CPU), aprocessing unit, a processing circuit, a processor, an Application Specific Integrated Circuit(ASIC), a microprocessor, or other processing logic that may interpret and executeinstructions. The herein utilised expression “calculation unit” may represent a processingcircuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above.

The control arrangement 43 may further comprise a memory unit, Wherein the calculationunit may be connected to the memory unit, which may provide the calculation unit with, for example, stored program code and/or stored data which the calculation unit may need to 16 enable it to do calculations. The calculation unit may also be adapted to store partial or finalresults of calculations in the memory unit. The memory unit may comprise a physical deviceutilised to store data or programs, i.e., sequences of instructions, on a temporary orpermanent basis. According to some embodiments, the memory unit may compriseintegrated circuits comprising silicon-based transistors. The memory unit may comprise e.g.a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile ornon-volatile storage unit for storing data such as e.g. ROM (Read-Only Memory), PROM(Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc. in different embodiments.

The control arrangement 43 is connected to components of the vehicle 5 for receiving and/orsending input and output signals. These input and output signals may comprise waveforms,pulses or other attributes which the input signal receiving devices can detect as informationand which can be converted to signals processable by the control arrangement 43. Thesesignals may then be supplied to the calculation unit. One or more output signal sendingdevices may be arranged to convert calculation results from the calculation unit to outputsignals for conveying to other parts of the vehicle's control system and/or the component orcomponents for which the signals are intended. Each of the connections to the respectivecomponents of the vehicle 5 for receiving and sending input and output signals may take theform of one or more from among a cable, a data bus, e.g. a CAN (controller area network)bus, a MOST (media orientated systems transport) bus or some other bus configuration, or a wireless connection. ln the embodiments illustrated, the retarder arrangement 40 comprises a controlarrangement 43 but might alternatively be implemented wholly or partly in two or more control arrangements or two or more control units.

Control systems in modern vehicles generally comprise a communication bus systemconsisting of one or more communication buses for connecting a number of electronic controlunits (ECUs), or controllers, to various components on board the vehicle. Such a controlsystem may comprise a large number of control units and taking care of a specific functionmay be shared between two or more of them. Vehicles of the type here concerned aretherefore often provided with significantly more control arrangements than depicted in Fig. 1 and Fig. 2, as one skilled in the art will surely appreciate.

The computer program product 200 may be provided for instance in the form of a data carrier carrying computer program code for performing at least some of the method steps 110 and 17 120 according to some embodiments when being loaded into one or more calculation units ofthe control arrangement 43. The data carrier may be, e.g. a CD ROM disc, as is illustrated inFig. 6, or a ROM (read-only memory), a PROM (programable read-only memory), anEPROM (erasable PROM), a flash memory, an EEPROM (electrically erasable PROM), ahard disc, a memory stick, an optical storage device, a magnetic storage device or any otherappropriate medium such as a disk or tape that may hold machine readable data in a non-transitory manner. The computer program product may furthermore be provided as computerprogram code on a server and may be downloaded to the control arrangement 43 remotely,e.g., over an lnternet or an intranet connection, or via other Wired or Wireless communication systems. lt is to be understood that the foregoing is illustrative of various example embodiments andthat the invention is defined only by the appended claims. A person skilled in the art willrealize that the example embodiments may be modified, and that different features of theexample embodiments may be combined to create embodiments other than those describedherein, Without departing from the scope of the present invention, as defined by the appended claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one ormore stated features, elements, steps, components or functions but does not preclude thepresence or addition of one or more other features, elements, steps, components, functions or groups thereof.

Claims

1. CLA|I\/IS 1. A retarder ertengemertit '402 cernensing e hydrodynamic retarder (1) configured to brakea shaft (3) of a vehicle (5), wherein the retarder (1) comprises:- a retarder housing (7) with a shovel space (9),- a shovel arrangement (11, 13) arranged in the shovel space (9),wherein the shovel arrangement (11, 13) comprises a shovel-equipped stator (11)and a shovel-equipped rotor (13) together forming a workspace (15),- an in|et channel (17) and an outlet channel (19) arranged to supply and evacuate,respectively, working fluid to and from the workspace (15),- a working circuit (9, 15, 19) comprising the shovel space (9), the workspace (15),and the outlet channel (19), and- a pressure sensor arrangement (21) configured to, at least selectively, sense thepressure at a first portion (23) of the working circuit (9, 15, 19) and at a secondportion (25) of the working circuit (9, 15, 19), wherein the second portion (25) isdifferent from the first portion (23)eharaeterizett in that the retarder arraheetnettt (403 eeanpräses a controlarraneesnettt (433. wherein the centret etrettcgentent :(43) is connected te the pressuresettsor arrangement t' 21"; and šs ccntäcttsttect to estimate a brakšnc; torque ot the retarder(t) based en sensed pressure att the tšrst nertâert tåßt ot the ttfnrkâhe circuit "9. 15- tQt ina first braking torque range. and te estâmate the brattšne torque ot the retarder (t) baseden sensecå etessure et the second eortioat :(25) ot the working citcutt (9, 15. 191: än aseczønd brakšne torque rartee. The retarder arrannentertt (46) according to claim 1, wherein the first portion(23) of the working circuit (9, 15, 19) is a portion of the outlet channel (19). The retarder ertsndernestt (49) according to claim 2, wherein the retarder (1)comprises a brake valve (27) arranged to restrict flow of working fluid through the outletchannel (19) so as to control the braking torque of the retarder (1), and wherein the firstportion (23) of the working circuit (9, 15, 19) is a portion of the outlet channel (19)upstream of the brake valve (27). The retarder' arraneernestt (49) according to any one of the preceding claims,wherein the second portion (25) of the working circuit (9, 15, 19) is a portion of theshovel space (9). |2o 10. 11.

2. The retarder arrangentesﬁt (49) according to any one of the preceding claims,wherein the pressure sensor arrangement (21) comprises a first pressure sensor (31)fluidly connected to the first portion (23) of the working circuit (9, 15, 19) and a secondpressure sensor (32) fluidly connected to the second portion (25) of the working circuit(9, 15, 19). The retarder' arrandenterat (43) according to any one of the claims 1 - 4,wherein the pressure sensor arrangement (21) comprises one pressor sensor (35) only. The retarder arrangentestt (49) according to claim 6, wherein the retarder (1)comprises a valve (37) fluidly connected to the first and second portions (23, 25) of theworking circuit (9, 15, 19) and to the pressure sensor (35), and wherein the valve (37)comprises a first state in which the valve (37) opens a fluid connection between thepressure sensor (35) and the first portion (23) and closes a fluid connection between thepressure sensor (35) and the second portion (25), and a second state in which the valve(37) opens the fluid connection between the pressure sensor (35) and the secondportion (25) and closes the fluid connection between the pressure sensor (35) and thefirst portion (23). The retarder arrangement (413) according to claim 7, wherein the valve (37)is arranged to switch between the first and second states based on a pressure levelsupplied from a pressure source (23, 25, 39). The retarder' arrangement (46) according to claim 8, wherein the pressuresource (23, 25) is one of the first and second portions (23, 25) of the working circuit (9,15, 19). The retarder arrangement 'ilüt according to claim 9, wherein the pressuresource (25) is the second portion (25) of the working circuit (9, 15, 19), and wherein thevalve (37) is configured to switch from the first state to the second state when thepressure at the second portion (25) reaches above a predetermined pressure level. The retarder' arrandesnestt (413) according to claim 10, wherein the valve (37)is configured to switch from the second state to the first state when the pressure at thesecond portion (25) drops below the predetermined pressure level. ~ .~ n; :_\_\ n i . s. ~ ner. '.nA-n at! AQ 3 i; 0.9 ¿ g “ ““ igecccbmﬂ I . Q . ef. ¿ .ge- :... ._ c , aeeer-fái-ng-fee--array--eneof-the--preeed-š-ng-etaäens,-vrf:er-ein-the-een-trei--arrarigement-:Aêš--âs šnrma: *F 'Hm rnﬂlrfavﬂ r ('11 lf-t ond n nonﬂf nrnooxzrn å H-'an « nrå r~ vil; n 105) 'F Ha~ s-»Euw v» u v: »<4 1 ywcx-.J-.J «..~ en., ~~..>-... F en» e.. ut. »av vuv-»w kw., w..- ,_>.. ; u; ___________The retarder arrangement (40) according to elainæ-tëanxf one of the precedinc;claims, wherein the first braking torque range is lower than the second braking torque range. transmission arrangement (50) configured to transmit power between apower source (53) of a vehicle (5) and wheels (55) of a vehicle (5), and wherein thetransmission arrangement (50) comprises a retarder arrangement (40) retar-'der--f-f--jiaccording to any one of the claims 1 - iii-lg, and wherein the retarder (1) of the retarderarrangeeneitt (401 is configured to brake a shaft (3) of the transmission arrangement(50). _. _______________ __A power train (60) for a vehicle (5), wherein the power train (60) comprises apower source (53) and a transmission arrangement (50), wherein the transmissionarrangement (50) is configured to transmit power between the power source (53) andwheels (55) of the vehicle (5), wherein the power train (60) comprises a retarderarrandeirtent (401 according to any one of the claims 1 - Jet-lg, and whereinthe retarder (1) of the retarder arrangement ('40) is configured to brake a shaft (3) of thepower train (60). vehicle (5) comprising a power train (60) according to claim 15131. -.\ method (100) of estimating a braking torque of a retarder (1 ), wherein the retarder (1) comprises: - a retarder housing (7) with a shovel space (9), - a shovel arrangement (11, 13) arranged in the shovel space (9),wherein the shovel arrangement (11, 13) comprises a shovel-equipped stator (11) and a shovel-equipped rotor (13) together forming a workspace (15), - an inlet channel (17) and an outlet channel (19), arranged to supply and evacuate,respectively, working fluid to and from the workspace (15), 3,....1 , .'u/f/w \' i”. .aa \~ Ö 4 - a working circuit (9, 15, 19) comprising the shovel space (9), the workspace (15),and the outlet channel (19),- a pressure sensor arrangement (21), and- a control arrangement (43) connected to the pressure sensor arrangement (21 ),wherein the method (100) comprises:- estimating (110) the braking torque based on sensed pressure at a first portion(23) of the working circuit (9, 15, 19) in a first braking torque range, and- estimating (120) the braking torque based on sensed pressure at a secondportion (25) of the working circuit (9, 15, 19) in a second braking torque range,wherein the second portion (25) is different from the first portion (23). computer program comprising instructions which, when the program isexecuted by a computer, cause the computer to carry out the method (100) according toclaim Hig. _______________ _VA computer-readable medium (200) comprising instructions which, when executed by a computer, cause the computer to carry out the method (100) according toclaim »fšilå _______________ __A control arrangement (43) for a retarder (1 ), wherein the retarder (1)comprises:- a retarder housing (7) with a shovel space (9),- a shovel arrangement (11, 13) arranged in the shovel space (9),wherein the shovel arrangement (11, 13) comprises a shovel-equipped stator (11)and a shovel-equipped rotor (13) together forming a workspace (15),- an inlet channel (17) and an outlet channel (19), arranged to supply and evacuate,respectively, working fluid to and from the workspace (15),- a working circuit (9, 15, 19) comprising the shovel space (9), the workspace (15),and the outlet channel (19), and- a pressure sensor arrangement (21),wherein the control arrangement (43) is configured to:- estimate the braking torque based on sensed pressure at a first portion (23) ofthe working circuit (9, 15, 19) in a first braking torque range, and- estimate the braking torque based on sensed pressure at a second portion (25)of the working circuit (9, 15, 19) in a second braking torque range, wherein thesecond portion (25) is different from the first portion (23).