SE1550887A1

SE1550887A1 - Hydrodynamic retarder device

Info

Publication number: SE1550887A1
Application number: SE1550887A
Authority: SE
Inventors: Färm Johnny
Original assignee: Scania Cv Ab
Priority date: 2015-06-26
Filing date: 2015-06-26
Publication date: 2016-12-27
Also published as: WO2016209149A1; SE539583C2; CN107709723A; DE112016002339T5

Abstract

28 Abstract The invention relates to a hydrodynamic retarder device, comprising a rotor(20) and a stator (42) which together form a workspace (44) connected to afirst fluid circuit (49), and a first expansion vessel (72) connected to the firstfluid circuit (49). A second expansion vessel (73) is connected to the work-space (44), which second expansion vessel (73) is arranged to supply fluid(46) to the workspace (44). The invention also relates to a vehicle (1) compris-ing such a hydrodynamic retarder device (2). The invention also relates to amethod of controlling a hydrodynamic retarder device (2). (Fig. 2)

Description

Hydrodynamic retarder device BACKGROUND AND PRIOR ART The present invention relates to a hydrodynamic retarder device according tothe preamble of patent claim 1, a vehicle, which comprises such a hydrody-namic retarder device according to the preamble of patent claim 15, and amethod for controlling a hydrodynamic retarder device according to thepreamble of patent claim 16.

A hydrodynamic retarder device is arranged to brake a driving source, such asa propeller shaft in a vehicle. Often the retarder is used as an auxiliary brake,which complements the wheel brakes of the vehicle. Thus excessive wear ofthe wheel brakes is avoided. The retarder comprises a rotor and a stator,which together form a workspace having a toroidal geometrical form. Theworkspace must be filled with a fluid, such as water, coolant or oil as quickly aspossible when a braking torque from the retarder is requested. A slow fillinginitially leads to a lack of a braking torque from the retarder, which leads to anexaggerated use of the wheel brakes of the vehicle, since the wheel brakesare used to brake the vehicle before the retarder delivers sufficient torque. Thismay result in unnecessary wear of the wheel brakes.

A hydrodynamic retarder device is typically used to brake the vehicle at highbraking torques or during long duration of the braking process, e.g. whentravelling down a slope. When the retarder is activated, the wheel brakes arenot activated. Therefore, the wheel brakes of the vehicle are not exposed to U n neCeSSafy Wear.

When water or coolant is used as fluid in the workspace the braking torque iscontrolled by means of the volume of water or coolant filled in the workspace.High braking torques exerted by the retarder are achieved when theworkspace is completely or substantially completely filled with water or coolant.

The volume of fluid in the workspace is controlled by means of one or a num-ber of restriction valves arranged in a fluid circuit connected to the workspace.The pressure within the workspace increases when the flow of fluid is re-stricted from the workspace. When the restriction valve in an outlet channelfrom the workspace is opened the volume of fluid within the workspace willdecrease, which in turn results in a reduced pressure within the workspace.The fluid or a part of the volume of fluid in the workspace will then evaporatedue to the decrease of the static pressure in the workspace to a level whichcoincides with the vaporizing point for the fluid. However, the pressure will notreach the vaporizing point for the fluid in all parts of the workspace and there-fore a small volume of fluid may be left in the workspace despite the preferredevacuation. This small volume of fluid left in the workspace will contribute to abraking torque on the vehicle. For this reason it is difficult to control the re- tarder at the lowest braking torques.

The cooling system for the engine in a vehicle is provided with an expansionvessel. Since the temperature and pressure in the cooling system varies, alsothe volume of coolant in the expansion vessel varies. When providing a vehiclewith a hydrodynamic retarder device having coolant fluid or water as workingfluid, the variations of the coolant volume in the expansion vessel are en-hanced. For this reason, the expansion vessel in the cooling system must bereplaced with a larger expansion vessel which contains a larger volume ofcoolant fluid. However, in some cases there will not be enough space for a lar-ger expansion vessel in the vehicle. Also, there are standardization sizes ofexpansion vessels, which make it difficult to replace a specific expansion ves- sel with another, larger expansion vessel.

Also, when the cooling system for the engine is connected to the fluid circuit ofthe retarder, pressure pulses occur in the cooling system when the retarder isactivated and deactivated. This vvill result in that the coolant volume in the expansion vessel varies.

Under some driving conditions it would be helpful for the driver to use the re-tarder to brake the vehicle, for example at gently sloping downhills and whenthe cruise control is activated. Under such driving conditions, controllable lowbraking torques from the retarder would be useful.

The retarder is connected to the powertrain of the vehicle via a retardertransmission. ln order to reduce energy losses and thus reduce the fuelconsumption of the vehicle, the retader transmission is disconnected so thatthe retarder is disconnected from the powertrain when the retarder is deactivated and not braking the vehicle.

When the workspace is filled with fluid the rotor starts to rotate and a torque isexerted on the powertrain via the rotating rotor. This torque is used as brakingtorque when the retarder is coupled to the powertrain in the vehicle.

The fluid is evacuated from the workspace when no braking torque should beprovided. However, when fluid has been evacuated from the workspace thepowertrain of the vehicle still rotates the rotor, which results in a small amountof residual torque acting on the powertrain. The residual torque results in anincreased fuel consumption of the vehicle. ln order to reduce the fuel consumption the rotor is disconnected from thepowertrain by means of a coupling element when the retarder is deactivatedand should not brake the vehicle. Thus, the rotor will substantially stand stilland not rotate when the rotor is disconnected from the powertrain.

However, if a small volume of fluid is left in the workspace the torque on therotor will be too high the next time the retarder is activated and the rotor isconnected to the powertrain. The reason for this is the small volume of fluid leftin the workspace. A too high torque at the moment of connecting the rotor tothe powertrain results in a substantial stress on the mechanical coupling ele-ment between the rotor and powertrain. ln order to solve this problem an evacuation pump may be installed into the fluid circuit which pumps the resid- ual fluid out from the workspace before connecting the rotor to the powertrain.

Depending on the amount of fluid left in the workspace at the moment of con-necting the rotor to the powertrain the capacity of the vacuum pump must beconsiderably high to ensure that all fluid can be evacuated fast enough. Also, ifthe evacuation pump fails, fluid may be left in the workspace when the rotor isconnected to the powertrain. As a result, a substantial stress on the mechani-cal coupling element between the rotor and powertrain will occur due to a toohigh torque at the moment of connecting the rotor to the powertrain, which maylead to a failure in the mechanical coupling element.

The document EP125105O A1 shows a retarder for vehicles with a rotor andstator, wherein the rotor is arranged to be connected and disconnected to thepropeller shaft of the vehicle by a clutch device which is pneumaticallycontrolled.

The document US2012222633 A1 shows a cooling system for a vehicle com-prising a compensation chamber, which is provided with a working medium fora hydrodynamic coupling. However, such compensation chamber is designedto be adapted to both the cooling system and the characteristics of the hydro- dynamic coupling.

SUMMARY OF THE INVENTION Despite prior art, there is a need to develop a hydrodynamic retarder device,which prevents changes in the amount of liquid in the coolant system connected to the hydrodynamic retarder device.

Also, there is a need to develop a hydrodynamic retarder device, which facilitates the connection of the rotor in the retarder to a povvertrain in a, vehicle and which faciiitates the controlling of oraking toroue at the lowest toroue Eevels.

The object of the present invention is thus to provide a hydrodynamic retarderdevice of the type defined in the introduction, which prevents changes in theamount of liquid in the coolant system connected to the hydrodynamic retarder device.

Another object of the present invention is to provide a hydrodynamic retarderdevice of the type defined in the introduction, which faciiitates the connection of the rotor in the retarder to a povtfertraän in a vehicte.

Stift another object of the present invention is to provide a hydrodynamic re-tarder device of the type defined in the introduction, which faciâitates the controltäng of braking toroue at the iowest toroue ieveis.

These objects are achieved with a hydrodynamic retarder device, which is characterized by the features specified in patent claim 1.

These objectives are also achieved with a vehicle which comprises such a hy-drodynamic retarder device, which is characterized by the features specified in patent claim 15.

These objectives are also achieved with a method of controlling such a hydro-dynamic retarder device, which is characterized by the features specified inpatent claim 16.

These objectives are also achieved with a computer program for controllingsuch a hydrodynamic retarder device according to the patent claim 20.

These objectives are also achieved with a computer program productaccording to the patent claim 21.

According to the invention, an advantageous hydrodynamic retarder device isachieved, comprising a rotor and a stator which together form a workspaceconnected to a first fluid circuit, and a first expansion vessel connected to thefirst fluid circuit. The first expansion vessel is a part of the cooling system ofthe vehicle. A second expansion vessel is connected to the workspace, whichsecond expansion vessel is arranged to supply fluid to the workspace. Whensupplying fluid from the second expansion vessel to the workspace in order togenerate braking torque on the rotor, the cooling system of the vehicle will notbe affected, because the volume of fluid in the first expansion vessel will pri-marily not be used to fill the workspace. When water or coolant is used as fluidfor the retarder, some of the water or coolant is evaporated into steam andsome water or coolant remains in liquid phase. ln the first fluid circuit substan- tially all water or coolant will remain as liquid.

According to an embodiment of the invention a vacuum chamber is connectedto the workspace, which vacuum chamber is arranged to remove fluid from theworkspace. This faciåitates the connection of the rotor of the retarder te apotvertrain in a vehicie and also facäšitates the controilâng of braking torque atthe Eovvest torque Eevels. The vacuum chaahbet' always has a pressure beiewatrnesphere prta-ssure. When the retarder should be activated the torque on therotor will be at an acceptable level when connecting the rotor to the powertrain.Before connecting the rotor to the powertrain any small volume of fluid left inthe workspace is removed from the workspace by means of suction force gen-erated by the vacuurn chamber. The mechanical coupling element betweenthe rotor and powertrain will then be subjected to torques at acceptable levels.Under certain driving conditions, such as gently sloping downhills, the drivermay use the retarder to brake the vehicle. Also, under such driving conditionsthe cruise control may be activated. This is possible since any residual fluid inthe workspace can be removed by means of the vacuum chamber. Since apressure under atmosphere pressure has been established in the workspacealso vaporized fluid may be removed by means of the vacuum chamber. Thus, it may be possible to control the retarder at lower braking torques since thevacuum chamber will control the remaining volume of fluid or vaporized fluid to a very low level in the workspace According to another embodiment of the invention the second expansion ves-sel and the vacuum chamber are arranged in a common housing and sepa-rated by means of a partition wall. Such housing can be designed and ar-ranged at any suitable place in the vehicle.

According to another embodiment of the invention the second expansion ves-sel is arranged in fluid connection with the vacuum chamber. ln order toevacuate fluid from the workspace the fluid is first led to the vacuum chamberbefore it is transferred to the second expansion vessel. The vacuum chamberwill accumulate any pressure peaks in the first fluid circuit and in the first ex-pansion vessel when the fluid is pushed out of the workspace due to the posi-tive pressure created in the workspace by the vanes of the rotor when the rotoris rotated.

According to another embodiment of the invention the vacuum chamber has afixed volume. Such a vacuum chamber will have no movable parts which mayfail or which may cause a leakage. Therefore, the pressure below atmospherepressure lrl the vaouorit oherhber will always be available in order to facilitatethe oohrteotiori ol the rotor ol the retarder to the povvertrelrl ih the vehicle andalso to fecllitate the cohtrolllhg of breklhg torque at the lotvest toroue levels.

According to still another embodiment of the invention the workspace and thevacuum chamber are arranged in fluid connection with a vacuum circuit. lt isuseful to arrange the vacuum chamber in a separate vacuum circuit, so thatother components that cooperate with the vacuum chamber can be connected to the vacuum circuit.

According to still another embodiment of the invention a vacuum pump is ar-ranged inside or outside of the vacuum circuit for generating vacuum or nega-tive pressure in the vacuum chamber. The vacuum pump ensures that thepressure in the vectiorrt chamber wiii eiweye be oeiow atmosohere pressure inorder to facilitate the connection oi the rotor ot the reterder to the oowertrain inthe vehioie and also to facâiitete the controittng ot breking torque et the iowesttorooe ieveie.

According to still another embodiment of the invention the vacuum pump is areciprocating piston pump arranged between two or more check valves in thevacuum circuit. The reciprocating piston pump may also be used in combina-tion with the vacuum chamber to remove any residual fluid in the workspace.

Other types of pumps than reciprocating piston pumps may be used.

According to still another embodiment of the invention the vacuum pump isarranged in the vacuum chamber. When the vacuum pump is arranged in the vacuum chamber no additional space is needed in the vehicle for the vacuum pump.

According to still another embodiment of the invention the first fluid circuitcomprises a first controllable valve for connecting/disconnecting the first fluidcircuit and the first expansion vessel to/from the workspace. The first controlla-ble valve connects the first fluid circuit and the first expansion vessel to theworkspace tfvhert the vvorkspace hes been tiiied vvith fiuid from the second ex-pansion vessel. The fluid will then circulate in the first fluid circuit and pass acooler arranged in the first fluid circuit. When the first controllable valve dis-connects the first fluid circuit and the first expansion vessel from the work-space no fioid may enter the workspace irorri the first fluid circuit and the firstexpansion vessel. The vacuum chamber may then remove all fluid from theworkspace, before the rotor ot the reterder wifi be connected to the povvertrain, or for oontroiiing brahâng torque et the iowest torque ieveis.

According to still another embodiment of the invention the vacuum circuit com-prises a second controllable valve for connecting/disconnecting the vacuumchamber to/from the workspace. This faoitttartes the connection ef the rotor ofthe retarder to the powertraih in the vehëcie, because when the second control-lable valve connects the vacuum chamber with the workspace the vacuumchamber removes substantially all fluid from the workspace, before the rotor ofthe retarder Witt be certhected to the pevvertrašrt. Also, the cohtrottšhg ot brakingtorque et the towest torque tevets they be facštitated sšhce the vacuum cham-ber removes fluid from the workspace in order to decrease the braking torquewhen the second controllable valve is connected the vacuum chamber with the workspace.

According to still another embodiment of the invention the workspace and thesecond expansion vessel are connected to a second fluid circuit. The secondfluid circuit may be isolated from the first fluid circuit, so that the cooling systemof the vehicle will not be affected when fluid is supplied from the second ex-pansion vessel to the workspace in order to generate braking torque on therotor. Also, pressure pulses may be avoided in the cooling system when theretarder is activated and deactivated.

According to still another embodiment of the invention the second fluid circuitcomprises a third controllable valve for connecting/disconnecting the secondexpansion vessel to/from the workspace. When the third controllable valveconnects the second expansion vessel with the workspace, fluid is flowing fromthe second expansion vessel into the workspace. Depending on requestedtorque from the retarder the third controllable valve will be controlled to deliver a predetermined volume of fluid to the workspace.

According to still another embodiment of the invention the vacuum circuit isconnected to the first and second fluid circuits. Thus, the vacuum circuit and the first and second fluid circuits may be arranged as a common closed circuit.

BRIEF DESCRIPTION OF THE DRAWINGS Below is a description of, as examples, preferred embodiments of the invention with reference to the enclosed drawings, in which: Fig. 1 shows schematically a vehicle in a side view, with a hydrodynamic re- tarder device according to the invention, Fig. 2 shows a sectional view of a hydrodynamic retarder device according to a first embodiment of the invention, Fig. 3 shows a sectional view of a hydrodynamic retarder device according to a second embodiment of the invention, and Fig. 4 shows a flow chart according to a method of controlling a hydrodynamic retarder device according to the invention.

DETAILED DESCRIPTION OF PREFERRED EI\/IBODII\/IENTS OF THEINVENTION Fig. 1 shows a schematic side view of a vehicle 1, which is equipped with ahydrodynamic retarder device 2 according to the present invention. Thevehicle 1 is also equipped with a powertrain 4 comprising a gearbox 6, which isconnected to a combustion and/or electric engine 8, which provides a drivingtorque to the driving wheels 10 of the vehicle 1 via the gearbox 6 and apropeller shaft 12. The driving wheels 10 are provided with wheel brakes 11.

An electronic control unit 16 is arranged for controlling the retarder 2.

Fig. 2 shows a sectional view of a retarder 2 according to a first embodiment ofthe invention. A first shaft 18 is connected to a rotor 20 of the retarder 2 and asecond shaft 22 is adapted to be connected to a driving source. According toFig. 2 the driving source is provided in the vehicle 1, where the connection of 11 the retarder 2 to the vehicle 1 is performed by the gearbox 6, which thusconstitutes the driving source. ln Fig. 2, the gearbox 6 is schematicallypresented. The second shaft 22 may therefore be a propeller shaft 12, which isboth connected to the gearbox 6, and to the drive wheels 10 of the vehicle 1.The second shaft 22 may also be an output shaft in the gearbox 6.

A transmission 26 in the form of a first gear wheel 24 arranged on the firstshaft 18 engages with a second gear wheel 28, which is releasably arrangedon the second shaft 22. Preferably, there is an upshift of the rotational speedof the second shaft 22 through the transmission 26 in the order of 3:1, butother ratios are possible such as 1 :1. The first shaft 18 is preferably, by meansof bearings 36 and 37, mounted in a retarder housing 40 and possibly also in agearbox housing 38. The rotor 20 is provided on the first shaft 18, which in anengaged state of the retarder 2 rotates at a speed proportional to the speed ofthe second shaft 22. A stator 42 is connected to the retarder housing 40 andwill therefore not rotate.

The rotor 26 and stator 42 together form a workspaoe 44 having the forrn of atoroidai hoiiow space. The tvorkspace is fiiied vvith a iiuid 46, such as vvater orcooiant through a first and second iniet opening 47, 51 when the retarder 2 isreouested to exercise a orakirfg tordue on the second shaft 22 connected tothe gearbox 6 in order to brake the vehicie t and thereioy decrease or rnairttairtthe speed of the vehicie t. Primary, fiuid 46 wiii enter the second iniet opening51 and secondiy, fiuid 46 wifi enter the first iriiet opening 4? tvheri theworitspace 44 has been fiiied with fiuid 46 from the second iniet opening 51.

The oraiting toroue is generated toy the rotor 26 and stator 42 which areprovided vvith ioiades or vanes 48, which creates a fiuid fiow in the workspace44 when the rotor 2G rotates. The fiuid fiow forms in ooniurtction with the venes48 of the rotor 20 and stator 42 a reaction force, irvhich resuits in the brakingeffect. The higher the speed of the rotor 26 and the greater the amount of fiuid46 in the workspace 44, the iarger is the reaction force and thus the braking 12 torque. On occasions vvhen the retarder 2 sitooid not brake the vehicie t theworitsoace 44 is drained whoiiy or oartiy of the fiuid 46 and the fioid is reoiacedin part by steam, caosing the vartes 48 ot the rotor Qi) and stater 42 to create asteam fiow in the worksoace 44. i-iowever. the steam tiow otters anondesirabie reaction force oh the *first shaft 18, which generates anondesirabie braking torque oh the second shaft 22. The braking torque fromthe retarder 2 thus causes an increased ftiei constimotich ot the vehioie t.Aiso, the friction from the beatings Bo and 37 ahd seais se of the first shatt tSgenerate a reaction torce, which restiits ih an increased toei consumption. Forthis reasoh, the first shaft 18 may be disccnnected frorh the second shaft 22when the retarder 2 is not used to braite the vehicie t. Thos, the tueiconsumption ot the vehicie t is reduced. Fiiiihg the woritspace 44 with the tioid46 is made via a second tioid circoit 83 and draitting is anade via a vacoumcircuit Tâš. i-iowever, smaii changes ih torque are made by means ot oontroiiiirigthe controi vaive 69, When the retarder 2 should be activated the workspace 44 must be filled withfluid 46 as quickly as possible to achieve braking torque from the retarder 2. Aslow filling leads to an initial loss of braking torque from the retarder 2,resulting in an excessive use of the wheel brakes 11, which will be subjected to unnecessary wear.

The disconnectable second gear wheel 28 on the second shaft 22 causes thefirst shaft 18 and thus the rotor 20 in the retarder 2 to be disconnected from thetransmission 6, so that the retarder 2 is not operating with a braking torque onthe vehicle 1 when the retarder 2 is deactivated. When the retarder 2 is to beactivated, the retarder 2 must in a fast and efficient way be mechanicallyconnected to the outgoing second shaft 22 in the gearbox 6. To accomplishthis, a coupling element 54 is arranged between the second gear 28 and thesecond shaft 22. The coupling element 54 preferably comprises a synchronization device provided with synchronizing rings (not shown). Such a 13 synchronizing device is common in gearboxes. lt is also possible to design the coupling element 54 as a friction clutch, such as a disk clutch.

When the retarder 2 is astiveted to braite the vehicie t the eeupiirtg eierneht 54is thus eetiveted se that the seeend geer wheei 28 is ceupied te the seeertcishait 22 by rneens ef the ceupitng eierhent 54. Since the secend sheft 22retates during engegernent and the tirst sheft 18 is stetienery, the ceupiingeiernent 54 vviit eeuse the first sheft 18 te retate via the trehsthtssien 26. Theseupiihg eiernent 54 is dimensiened to be ahie te transrnit the ierge braitiirig torque exerted by the retarder 2 en the seeend sheft 22.

A second expansion vessel 73 is connected to the workspace, which secondexpansion vessel 73 is arranged to supply fluid 46 to the workspace 44. This ispossible since the expansion vessel 73 is pressurized by the pressurized air91 at the top of the expansion vessel 73 above the fluid surface 93. The ex-pansion vessel 73 is completely filled with air when the retarder 2 is assem-bled. When supplying fluid 46 from the second expansion vessel 73 to theworkspace 44 in order to generating braking torque on the rotor 20, either atthe beginning of the braking or when increasing the braking torque, a coolingsystem 55 of the vehicle 1 will not be affected, because the volume of fluid 46in a first expansion vessel 72 will primarily not be used to fill the workspace 44.The first expansion vessel 72 constitutes a part of the cooling system 55 of thevehicle 1. Also, a vacuum chamber 76 is connected to the workspace 44,which vacuum chamber 76 is arranged to remove fluid 46 from the workspace44 in order to reduce the braking torque on the rotor 20 or to empty all the fluid46 from the workspace 44. A small decrease of the braking torque on the rotor20 can be adjusted by the control valve 60. This taciiitetes the connection ofthe reter 20 ei the retarder 2 te e petvertreirt in e vehieie 'i ehd also feciiitetesthe eentreiiing ef braking tetqtie at the ievvest torque ieveis. The vercuuntchemher' 76 is arranged te eitveys have e negative pressure er e pressurebeiew atmesphere pressure. When the retarder 2 is to be activated, the torqueon the rotor 20 should be at an acceptable level when connecting the rotor 20 14 to the powertrain 4. Before connecting the rotor 20 to the powertrain 4 anysmall volume of fluid 46 left in the workspace is therefore removed from theworkspace 44 by means of suction force generated by the vacuum chamber76. As a result the mechanical coupling element 54 between the rotor 20 andpowertrain 4 will then be subjected to torques at acceptable levels. Under cer-tain driving conditions, such as gently sloping downhills, the driver may use theretarder 2 to brake the vehicle 1. Also, under such driving conditions the auto-matic cruise control of the vehicle 1 may be activated. This is possible sinceany residual fluid 46 in the workspace 44 has been removed by means of thevacuum chamber 76 and since a pressure under atmosphere pressure hasbeen established in the workspace 44. Thus, it may be possible to control theretarder 2 at the lowest braking torques.

The second expansion vessel 73 and the vacuum chamber 76 are arranged ina common housing 77 and separated by means of a partition wall 79. Suchhousing 77 may be designed and arranged at any suitable place in the vehicle1. The second expansion vessel 73 is connected to the vacuum chamber 76through a connection pipe 81. The workspace 44 and the vacuum chamber 76 are connected to a vacuum circuit 78.

A vacuum pump 63 is arranged in the vacuum circuit 78 for generating thenegative pressure in the vacuum chamber 76. Preferably, the vacuum pump63 is a reciprocating piston pump 63, and according to the first embodimentthe pump 63 is arranged between two check valves 80, 82 in the vacuum cir-cuit 78. The vacuum pump 63 may also be used in combination with the vac-uum chamber 76 to remove any residual fluid 46 in the workspace. Preferably,but not necessarily, the vacuum pump 63 is arranged in the vacuum chamber76 so that no additional space is needed in the vehicle 1 for the vacuum pump63. The vacuum pump 63 comprises a reciprocating piston 98 which is con-trolled by means of a power means 99. A spring 100 may be arranged withinthe vacuum pump 63 in order to push the piston in one direction of the recipro-cating movement. The vacuum pump 63 may also be of a design other than a reciprocating piston pump. Water or coolant, and steam within the vacuumChamber 76 are transferred to the second expansion vessel 73 through apump in|et 87 via the vacuum pump 63 and the two check valves 80, 82. Thetwo check valves 80, 82 are so arranged that the f|uid 46 may not enter thevacuum chamber 76 from the second f|uid circuit 83 or from the second ex- pansion vessel 73.

The vacuum circuit 78 comprises a second controllable direction valve 84 forconnecting/disconnecting the vacuum chamber 76 to/from the workspace 44.A first f|uid circuit 49 comprises a first controllable direction valve 64 for con-necting/disconnecting the first f|uid circuit 49 and the first expansion vessel 72to/from the workspace 44. The workspace 44 and the second expansion ves-sel 73 are connected to a second f|uid circuit 83, which is connected to theworkspace 44 by means of the second in|et opening 51. The second f|uid cir-cuit 83 comprises a third controllable direction valve 86 for connecting/ discon-necting the second expansion vessel 73 to/from the workspace 44. The vac-uum circuit 78 is connected to the first and second f|uid circuits 49, 83. Thesecond f|uid circuit 83 is connected to the second expansion vessel 73 via the connection pipe 81.

Each of the second and third controllable direction valves 84, 86 has three po-sitions. A first open position, a second closed position and third throttle position101, 102. ln the third position the f|uid 46 can pass the valve 84, 86 with a re-stricted flow and thus it is possible to adjust the flow of f|uid 46 in order to ad- just the torque of the retarder 2.

A pressure sensor 88 connected to the second expansion vessel 73 receiveinformation about the pressure within the second expansion vessel 73. Thus, itis possible to achieve information about the f|uid 46 level and the volume off|uid 46 inside the second expansion vessel 73. As an alternative the pressuresensor 88 may be reptaced by e, level sensor, rvhich cert detect the f|uid levelin the second expansion vessel 73. The pressure sensor 88 is also connected 16 to the control unit 16, so that it is possible to control the first, second and thirdcontrollable valves 64, 84, 86 together with the vacuum pump 63 in order tocontrol the fluid 46 volume and pressure within the second expansion vessel73.

An external condult 9G ts connected to the vacuum chamber 76. Through theexternal conduit 90, fluid 46 must be added to the vacuum chamber 76 in orderto remove air from the vacuum chamber 76 when assembling the retarder 2and to achieve the correct total volume of fluid 46 within the circuits 55, 78, 83and expansion vessels 72, 73 of the hydrodynamic retarder device 2. An open-ing and closing valve 92 is arranged in fluid connection with the external con-dult 96 to open and close the external condult 96.

As rnentlorted above, the fluld 46 supplied to the worltspace 44 ls oreteralzalytvater, such as cooling tfvater or cootant. When the tvorltspace 44 has heenfilled with vvater or coolant trorn the second expansloit vessel 73, water orcoolant ls added to the vvorltspace 44 from the cooling system 55 of thecombustion and/or electric engine 8. Thus, the fluid circuit 49 of the retarder 2is interconnected with the cooling system 55 of the combustion and/or electricengine 8 in order to cool the fluid 46 flowing through the vvorttspace 44. Thepraking toroue of the retarder 2 ls controlled hy the volurne of fluid 46 that tsaotlve ln the vvorkspace 44. The fluid 46 flow ls controlled toy a control valve 6Gvvhlch is dlsposed in fluid connection vvlth an outtet channel 6.2 from thetvorfltspace 44. By restrictlng the outftotftf of tluld 46 front the vvorkspace 44 hythe centret valve 60, the pressure p ln the vvorkspaee 44 tncreases. When thecontrol valve 6G opens, the volume of tluld 46 in the tfvorttspace 44 tvllldecrease, vvhloh ln turn causes the pleasure p in the vtforttspaoe 44 todecrease. The fluid 46, or a partiet volume of the tluld 46 oontalned in thevvorltsoace 44 vvill evaporate due to the taot that the static pressure p in thevvorltspaoe 44 olrops to the vaporizing point for the flutcl 46. 17 “tftihen deectivating the retarder 2, inftotftf of ftuid 46 in to the vvorhspaoe 44 isterrninated by ctosiitg the first and third oontroitabte direction vatves 64, 86.Thereafter the second ccntrottabte vatve 64 is ooened so that ftutd 46 can beevacuated from the vtforhspaee 44. iriovtfever, the oresstire o in parts of the»workspace 44 and the exhatist duct from the vvort-tsoaoe does not fatt hetowthe vaporizirtg point. Therefore, the ttutd 46 in the tfvort-tsnaoe 44 rnay tingerend stey in the workspace 44 desoite the desired evacuation of tiuid 46. Anyresiduai fiuid 46 in the »workspace 44 contributes to the untfirarited residuaitorque, which contrthutes to the increased fuet eonstintotion. However, whendisoonneoting the second gear wheet 28 from the second shatt 22 any resiotuattorque is etiinineted. ttowever. prohteins arise when the retarder 2 shouid be connected to thepowertrain 4 at the next occasion when hreking the vehicie t, because oi theftuid 46 present in the workspace 44. At the connection of the retarder 2 to thepowertrain 4 en tinacoeptehty high torque, which causes great stressas in thecounting eiement 54, rnay arise. Therefore, the vacuum Chamber 76 is ar-ranged to remove fluid 46 from the workspace 44 in order to faottitate theconnection of the rotor 20 of the retarder 2 to the powertrain 4 in the vehicte.The vacuum oharnber 76 is arranged to atways have e itegative pressure or apressure hetotv atmosphere pressure. When the retarder 2 is activated thetorque on the rotor 20 is desired to be at an acceptable low level when con-necting the rotor 20 to the powertrain 4. Before connecting the rotor 20 to thepowertrain 4 any small volume of fluid 46 left in the workspace 44 is thereforeremoved from the workspace 44 by means of suction force generated by thevacuum chamber 76. As a result the mechanical coupling element 54 betweenthe rotor 20 and powertrain 4 will then be subjected to torques at acceptable levels.

Preferably, the vacuum chamber 76 has a fixed volume. Such a vacuumchamber 76 will have no movable parts which may fail or which may cause aleakage. Therefore, the negative pressure in the vacuum chamber 76 witi 18 eiways be evaiiabte in order to facilitate the oonneotton of the rotor 2G to thepowertretn 4 and also to taetiitete the oontroitthg of brahing tordtie at the iowesttorotie ieveis trvhioh tfviti be explained in deteti betow. ii the pressure vvithin thevacuum Chamber 76 increases to a predetermined level a third check valve 85will open and fluid 46 may flow out to the first fluid circuit 49 through a bypass pipe 89, which connects the vacuum chamber 76 with the first fluid circuit 49.

The workspace 44 and the vacuum chamber 76 are connected to a vacuumcircuit 78. lt is useful to arrange the vacuum chamber 76 in a separate vacuumcircuit 78, so that other components that cooperate with the vacuum chamber76 also can be connected to the vacuum circuit 78.

When the second controllable valve 84 connects the vacuum chamber 76 withthe workspace 44 the vacuum chamber 76 removes all fluid 46 from the work-space 44, before the rotor 2G of the reterder 2 wtii be connected to thepowertrešn 4. if e component in the ftoid circuit 49 feiis, the fittid 46 witihowever rematn in the vvorhspeoe 44 et the ehgegerneht of the reteifder' 2,which teads to that the toroue becomes too ierge when oonneotthg the retarder2 to the powertrein 4. As e oreoetitionery measure, to prevent the ooopiingeierrteht 54 front being subiected to an exoessive torctue the oontroi unit t6monitors the engegernent of the reterder 2 so that the ertgegennertt torouedoes not exceed the mexirnom toroue thet the ooopiing eiernent 54 is designedtor. A pressure sensor 19 is provided et the workspace 44 whioh measures thepressure p in the workspace 44 or downstreem ot the »workspace 44. Thepressure p in the workspace 44 is proportional or almost proportional to thetorooe generated by the rotor 2G, Thus, the toroue of the rotor 26 and the tirstshatt 18 cert be oaiouiated in order to determine the tordoe when oonneotthgthe reterder 2 to the potrvertrein 4 by means of the ooopiing eiernent 54. A posi-tion sensor 95 measures the position of the coupling element 54, and the posi-tion sensor 95 is connected to the control unit 16. 19 The centret unit 'i6 is couoied to the pressure sensor ts, the centroi vaive 6Gend the soeed sensor 9. A tirst ccntreiiahie direction vaive 64 is eisoconnected te the centrei unit 16. The tirst centreiiahie direction vaive 64 isinciuded in the first fiuid circuit 49 and is opened and ciosed ey signais frontthe centret unit 16. During activatien ei the retarder 2 the centroiiahie directionvaive 64 is opened te sueoiy tiiiid 46 te the workspace 44 and when theretarder 2 is deectivated the eentreiiahie direction vaive 64 is ciesed so that nefiiiid 46 is siieeiied te the tvoritspace 44. The centroi unit “i6 is eise connectedte a newer eiernent 66 which ertgages and disengages the counting eieinent54. The newer eierrieitt 66 rnay he a hydrauiic er enetirnatic cyiinder er aneieetric motor that centrets the counting eiernent 54.

The first controllable direction valve 64 may disconnect the first fluid circuit 49and thus the first expansion vessel 72 from the workspace 44 se that ite tiuid46 may enter the tfvorkseace 44 trern the first fiuid circuit 46. Also the third con-trollable valve 86 is closed. The vaouum chamber 76 then removes all fluid 46from the workspace 44, before the reter 26 et the retarder 2 is connected tothe oewertrain 4. Also, the oontroiiing oi hraiting torque at the iowest torqueieveis rnay he faciiitated because the vaouum chamber 76 removes fluid 46from the workspace 44 in order to deorease the braking torque. The third con-trollable direction valve 86 may connect the second expansion vessel 73 to theworkspace 44 in order to increase the braking torque from the retarder.

The ceoiing system is eiso provided vvith a heat exchenger 76 and the tirstexpansion vessei ?2. A therrnostat vaive Tt arranged in the ceeiing system 55directs tiiiid 46 in a direction through the heat exchanger 7G er bypass theheat exohanger 7G deoending on the tenteerature of the fiuid 46. A eooientpump 68 is arranged te provide titiid 46 in the ceeiing system 55 and the fiuidcircuit 49 to tievv through the first contrciiehie vaive 64 and in to the workspace44 for ceoiing the iitiid 46 heated hy the increased pressure in the trverkseace44. The rotation of the reter 2G aise ournps and circoiates tiiiid 46 through firsttiuid circuit 55.

The vacuum Chamber 76 connected to the workspace 44, also factlätates thecohtrotlihg of braking torque at the lott/est torque levels. Under certain drivingconditions, such as gently sloping downhills, the driver may use the retarder 2to brake the vehicle 1. Also, under such driving conditions the cruise controlmay be activated. This is possible since any residual fluid 46 in the workspace44 can be removed by means of the vacuum chamber 76 and since a negativepressure has been established in the workspace 44. As a result, it is possibleto control the retarder 2 at the lowest braking torques.

The second and third controllable direction valves 84, 86 are coordinated andconnected to the electronic control unit 16 so that they together can control theretarder torque at the lowest torque levels. The vacuum chamber 76 removesfluid 46 from the workspace 44 in order to decrease the braking torque and thethird controllable valve 86 connects the second expansion vessel 72 to theworkspace 44 in order to increase the braking torque. The second controllablevalve 84 may connect the vacuum chamber 76 to the workspace 44 in order to increase and decrease the braking torque at the lowest torque levels.

Fig. 3 shows a sectional view of a hydrodynamic retarder device according to asecond embodiment of the invention. ln the second embodiment of theinvention the vacuum pump 63 is arranged between four check valves 80, 82,96, 97 in the vacuum circuit 78. When using four check valves 80, 82, 96, 97the reciprocating movement of the piston 98 in the vacuum pump 63 can beused in both directions. ln this embodiment the return spring 100, acting on thepiston 98, can be removed and the power means 99 for controlling the piston98 may be arranged to control the piston 98 in both directions. Using the recip-rocating movement of the piston 98 in both directions for pumping fluid 46 thepumping effect increases and the retarder 2 according to the invention mayrespond faster. The vacuum pump 63 ensures that the pressure in the vacuum chamber 76 always tvätt be belovv atmosphere pressure. According to the sec- 21 ond embodiment the vacuum pump 63 may also be used in combination with the vacuum chamber 76 to remove any residual fluid 46 in the workspace 44.

Fig. 4 shows a flow chart of the method for controlling a hydrodynamic retarderdevice 2, comprising the rotor 20 and the stator 42 which together form theworkspace 44 connected to the first fluid circuit 49, and the first expansionvessel 72 connected to the first fluid circuit 49.

The method comprises the step of: a) generating braking torque on the rotor 20 by supplying fluid 46 from thesecond expansion vessel 73 to the workspace 44 through the second fluidcircuit 83.

When supplying fluid 46 from a second expansion vessel 73 to the workspace44 through a second fluid circuit 83 in order to generate braking torque on therotor 20 the coo|ing system of the vehicle 1 will not be affected, because thevolume of fluid 46 in the first expansion vessel 72 is not used to fill the work-space 44.

The method further comprises the step of:b) supplying fluid 46 from the second expansion vessel 73 to the workspace 44by means of a positive air pressure in the second expansion vessel 73.

The energy from the existing positive air pressure 91 inside the second expan-sion vessel 73 is used to push the fluid 46 out of the second expansion vessel73 and further to the workspace 44. Thus, when the third controllable valve 86is opened the fluid 46 flows out of the second expansion vessel 73 due to thepositive air pressure 91 inside the second expansion vessel 73.

The method further comprises the step of: 22 c) evacuating f|uid 46 from the workspace 44 to the second expansion vesse|73 through a vacuum Chamber 76, which is connected to the workspace 44and the second expansion vesse| 73. ln order to deactivating the retarder 2 the f|uid 46 is evacuated from the work-space 44 and is first led to the vacuum chamber 76 before it is transferred tothe second expansion vesse| 73. The vacuum chamber 76 will accumulate anypressure peaks in the first f|uid circuit 49 and in the first expansion vesse| 72when the second controllable valve 84 is opened and the f|uid 46 is pushed outof the workspace 44 due to the positive pressure created in the workspace 44by the vanes 48 when the rotor 20 is rotated.

Preferably, f|uid 46 is pumped from the vacuum chamber 76 to the second ex-pansion vesse| 73 by means of the vacuum pump 63 arranged inside or out-side of the vacuum chamber 76.

When or during the vacuum chamber 76 is filled with f|uid 46 the vacuum pump63 arranged inside or outside of the vacuum chamber 76 pumps the f|uid 46out of the vacuum chamber 76 and into the second expansion vesse| 73. Theair 91 within the second expansion vesse| 73 is then compressed by the f|uid46 entering the second expansion vesse| 73.

The present invention also relates to a computer program P and a computerprogram product for performing the method steps. The computer program Pcontrols the method of controlling a hydrodynamic retarder device 2, whereinsaid computer program P comprises program code for making the electroniccontrol unit 16 or the computer 74 connected to the electronic control unit 16 toperforming the method steps according to the invention as mentioned herein,when said computer program P is run on the electronic control unit 16 or com- puter 74 connected to the electronic control unit 16. 23 The computer program product comprises a program code stored on the elec-tronic control unit 16 or computer 74 connected to the electronic control unit 16readable, media for performing the method steps according to the invention asmentioned herein, when said computer program P is run on the electronic con-trol unit 16 or the computer 74 connected to the electronic control unit 16. Al-ternatively, the computer program product is directly storable in the internalmemory l\/I into the electronic control unit 16 or the computer 74 connected tothe electronic control unit 16, comprising a computer program P for performingthe method steps according to the present invention, when said computer pro-gram P is run on the electronic control unit 16 or the computer 74 connected tothe electronic control unit 16.

According to the above, the retarder 2 ittay be provided at e vehicie “i torbreaking the vehicie t, bot it ie eieo possibie to use the reteroer 22 according tothe invention tor other eppiicaticns. According to the above, the vehicie t, thecombustion and/or electric engine 8, the transmission 6 or propeiier” sitatt 12cortstittrte e. drive source, vvhich directiy or iridirectty is ccupied to the retarcier 2. Other power sources can itovvetfer be connected to the retarder 2.

The components and features specified above may within the framework of theinvention be combined between the different embodiments specified.

Claims

24 Claims

1. A hydrodynamic retarder device, comprising a rotor (20) and a stator (42) which together form a workspace (44) connectedto a first fluid circuit (49), and a first expansion vessel (72) connected to the first fluid circuit (49),characterized in that a second expansion vessei (73) is connected to theworkspace (44), which second expansion vessel (73) is arranged to supplyfluid (46) to the workspace (44).

2. A hydrodynamic retarder device according to claim 1, characterized in thata vacuum chamber (76) is connected to the workspace (44), which vacuum chamber (76) is arranged to remove fluid (46) from the workspace (44).

3. A hydrodynamic retarder device according to any of claims 1 - 2, character-ized in that the second expansion vessei (73) and the vacuum chamber (76)are arranged in a common housing (77) and separated by means of a partitionwall (79).

4. A hydrodynamic retarder device according to any of claims 2 - 3, character-ized in that the second expansion vessei (73) is connected to the vacuumchamber (76).

5. A hydrodynamic retarder device according to any of claims 2 - 4, character-ized in that the vacuum chamber (76) has a fixed volume.

6. A hydrodynamic retarder device according to any of claims 2 - 5, character-ized in that the workspace (44) and the vacuum chamber (76) are connected to a vacuum circuit (78).

7. A hydrodynamic retarder device according to claim 6, characterized in thata vacuum pump (63) is arranged in the vacuum circuit (78) for generating anegative pressure in the vacuum chamber (76).

8. A hydrodynamic retarder device according to claim 7, characterized in thatthe vacuum pump (63) is a reciprocating piston pump arranged between atleast two, preferably four check valves (80, 82, 96, 97) in the vacuum circuit(78).

9. A hydrodynamic retarder device according to any of c|aims 7 - 8, character-ized in that the vacuum pump (63) is arranged in the vacuum chamber (76).

10. A hydrodynamic retarder device according to any of c|aims 6 - 9, charac-terized in that the vacuum circuit (78) comprises a second controllable direc-tion valve (84) for connecting and disconnecting the vacuum chamber (76) toand from the workspace (44), which second controllable direction valve (84)comprises a throttle position (101).

11. A hydrodynamic retarder device according to any of the preceding c|aims,characterized in that the first f|uid circuit (49) comprises a first controllabledirection valve (64) for connecting and disconnecting the first f|uid circuit (49)and the first expansion vessel (72) to and from the workspace (44).

12. A hydrodynamic retarder device according to any of the preceding c|aims,characterized in that the workspace (44) and the second expansion vessel(73) are connected to a second f|uid circuit (83).

13. A hydrodynamic retarder device according to claim 12, characterized inthat the second f|uid circuit (83) comprises a third controllable direction valve(86) for connecting and disconnecting the second expansion vessel (73) to andfrom the workspace (44), which third controllable valve (86) comprises a throt-t|e position (102). 26

14. A hydrodynamic retarder device according to claim 6 and any of claims 12- 13, characterized in that the vacuum circuit (78) is connected to the first andsecond f|uid circuits (49, 83).

15. Vehicle (1 ), characterized in that the vehicle (1) comprises a hydrody- namic retarder device (2) according to any of claims 1 - 14.

16. A method of controlling a hydrodynamic retarder device, comprising a rotor (20) and a stator (42) which together form a workspace (44) connectedto a first f|uid circuit (49), and a first expansion vessel (72) connected to the first f|uid circuit (49),characterized in that the method comprises the step of: a) generating braking torque on the rotor (20) by supplying f|uid (46) from asecond expansion vessel (73) to the workspace (44) through a second f|uidcircuit (83).

17. The method according to claim 16, characterized in the further step of:b) supplying f|uid (46) from the second expansion vessel (73) to the workspace (44) by means of a positive air pressure in the second expansion vessel (73).

18. The method according to claim 17, characterized in the further step of:c) evacuating f|uid (46) from the workspace (44) to the second expansion ves-sel (73) through a vacuum chamber (76), which is connected to the workspace (44) and the second expansion vessel (73).

19. The method according to claim 18, characterized inthat in step c) is f|uid (46) pumped from the vacuum chamber (76) to the sec-ond expansion vessel (73) by means of a vacuum pump (63) arranged in the vacuum chamber (76). 27

20. A computer program (P) for controlling a hydrodynamic retarder device (2),wherein said computer program (P) comprises program code for making anelectronic control unit (16) or computer (74) connected to the electronic controlunit (16) to performing the steps according to any of the claims 16 - 19.

21. A computer program product comprising a program code stored on a me-dia readable by a computer (74) for performing the method steps according toany of the claims 16 - 19, when said program code runs on an electronic con-trol unit (16) or computer (74) connected to the electronic control unit (16).