SE1450957A1 - Hydrodynamic retarder - Google Patents

Description

Starting from the above prior art, the purpose of the present invention is now to provide a hydrodynarnic retarder in which air iosses are reduced as much as possible, with iittie cost and compiexity.

Starting from the preamble of Ciaim i, this objective is achieved in combination with the characterizing features specified in that ciairn. The subsequent, dependent ciaims in each case describe advantageous further developments of the invention.

According to the invention, a hydrodynamic retarder comprises a rotor and a stator. in a manner whose principie is understood by those with knowledge of the field, braking torque can be exerted on the rotor since both the rotor and the stator are fitted with blades and can be hydrauiicaliy coupied With one another by the flow of a fiuid between the blades. The way this happens is that the tluid is propelled by the blades of the rotor and then impinges on the static blades of the stater, off which it bounces back to the rotor biades. The returning fluid then acts to siow down the rotor. in a drive-train of a motor vehicie the hydrodynamic retarder can be arranged either as a primary retarder between a drive engine and a motor vehicie transmission, or it can be connected downstream from the motor vehicie transmission as a secondary retarder. Particuiariy in the case of a secondary retarder, the retarder can be connected if necessary by way of a high-driver stage. Furthermore, the retarder can be integrated in the motor vehicie transmission or it can be an assembly separate therefrom.

The invention now adopts the technicai feature that the rotor and stator are arranged radiaily reiative to one another. in other words, the rotor and stator are positioned radiaily opposite one another, either with the rotor racliaiiy inside the stater or with the stator radiaiiy inside the rotor. Consequentiy, in each case the biades of the rotor and stator are also directed radiaiiy.

Such a hydrodynamic retarder design has the advantage that with this arrangement of the rotor and stater, measures to minimize air iosses can be implemented with iittie cost and cornpiexity. Thus, with the radiai configuration -ga according to the invention a fiow connection between the biades of the rotor and stator can be interrupted in a simple manner since the means that bring about the interruption can have a constant diameter during it. For example, in principle the extent of the interruption can be chosen freely. lvloreover, if necessary an axially space-saving arrangement of the hydrodynamic retarcier is possible if the rotor and stator are arranged radiaiiy to form an internal component of the motor vehicie transmission or of some other part of the drive-train. in contrast, the baffle-piates of the hydrodynamic retarder described in DE 10 2007 032 935 Ai are of complex design and can only to a certain extent interrupt the flow connection between the blades of the rotor and stater. in an ernbodiment of the invention, the rotor and stater are fitted with biades and means are provided by witich a fiuidic coupiing between the blades can be interrupted. in this context “fiuidic coupiingf' is understood to mean the coupling of the rotor and stator blades by way of a fiuid, wherein rotary movement of the rotor biades picks up fluid, which is then acceierated in the direction toward the stator biacies, from which it returns again toward the rotor blades. When the retarder is full, the fiuid is a liquid, in particular oil or water, whereas in the sometimes empty condition of the retarder the fiuid is air.

According to a first further development of this ernbodiment, the means consist in that the rotor and stator can move axially reiative to one another. in other words, in this case the flow of fluid between the rotor and stator can be infiuenced by axial displacement of the rotor and stator reiative to one another. in this way, during operation of the retarder when it is empty air turbulence and hence air iosses can be reduced since the rotor and stator blades are positioned with the minimum possible axial overiap. For this, it is in principle conceivable that either the rotor or the stator, or even both components are designed to be able to move axiaiiy. in an alternative design of the invention, the means are in the form of at least one axiaily rnovable sieeve that can be inserted radiaiiy between the retarder blades. This too can substantially reduce air turbuience during operation of the retarder when it is empty, since a flow connection between the biades is -3_ interrupted by the at least one sieeve inserted between them. in this case the sieeve is preferably made with a hotiow-cyiindrical section or entireiy as a hoilow cyiinder, and is introduced with that section or its entire body radiaiiy between the rotor and the stator. Consequently, an alt-round interruption of the fluidic coupiing can be achieved with iittle cornpiexity. it is also conceivabie, however, to provide a plurality of sleeves for the purpose. in a further development of the above design, the at least one sieeve is coupied to the rotor pr to the stator in a rotationaliy fixed manner. in this case, however, it is particuiarly preferabie to couple the sieeve to the rotor, so that air moved by the rotor biades during empty operation does not irnpinge on a static sleeve, but on one that moves in unison with the rotor.

A further design feature of the invention is that the at ieast one sleeve can be moved axiaily by an actuator and in opposition to at least one spring element.

The actuator can be an eiectricai actuator, for exarnpie a magnet or an eiectric motor, a hydraulic actuator, for exampie a hydraulicaiiy actuated piston, or a pneurnatic actuator such as a pneumaticaiiy actuated piston. The at ieast one spring eiement presses the sleeve either in the direction of an initiai, normai position in which the at ieast one sleeve does not extend between the rotor and stator, or toward a position where the sieeve extends completely between the rotor and stator, so that by means of the actuator a movement of the at ieast one sieeve in opposition to the pre-stressing of the spring element takes place.

Depending on whether the sleeve is fixed on the rotor or the stator, the at least one spring eiement can be supported at its end against the rotor or the stator. in another advantageous ernbodiment of the invention, the fiuidic coupling can be eiiminated cornpieteiy by the means. in this way air iosses during operation of the retarder whiie empty can be avoided eritireiy since no air can circuiate between the rotor and stator. ivloreover the retarder system as a vvhoie can be simpiified, since the fluid that produces a hydrauiic coupling between the rotor and stator can be ieft in piace and, other than during braking operation, the production of a braking torque is suppressed by the compiete separation described above. Consequently, it is no longer necessary to fill and empty the toroidai space of the hydrodynamic retarder. in a further development of the above embodiment and when the rotor and stator are designed to move axially relative to one another, a quantity of fiuid is heid perrnanently between the rotor and the stator, so that a bralting torque acting on the rotor can be adjusted by the axial positioning of the rotor and stator reiative to one another. ln this case, therefore, the torque that can be produced by the retarder is controlled not by regulating the quantity of fluid, but by adjusting the axial overlap of the rotor blades and stator blades. Consequently there is no longer any need for the correspondingly complex hydrauiic control system, which otherwise has to be provided for regulating the quantity of fluid.

Likewise also in the case when the means are in the form of at least one mot/able sleeve, a quantity of fluid can be held permanently in the torošdal space so that a braking torque acting on the rotor can be deterrrrlned by the extent to which the at least one sieeve is introduced axiaily into the toroidal space. Thus, in this case the braking torque required is produced by positioning the at least one sleeve appropriateiy between the blades. Accordingly, again there is no need for a complex hydraulic system to reguiate the quantity of fluld introduced into the toroidai space.

The invention is not limited to the combinations of characteristics lndicated in the principal claim or in the claims that depend on it. Other possibilities exist for combining with one another individual features, insofar as they emerge frorn the clalms, the description of preferred entbodlments given below, or directly from the drawings. The reference of the ciaims to the drawings hy the use of indexes is not intended to restrict the protective scope of the ciaims, Advantageous design features of the invention, which are explained betow, are represented in the drawings, which show: FigfhA schematic representation of a hydrodynamic retarder that corresponcls to a first embodiment of the invention, shown in a first condition; Fig. 2: Another schematic representation of the retarder in Fig. i, shown in a second condition; and Fig. 31A schernatic representation of a hydrodynamic retarder according to a second possible embodirnent of the invention.

Fig. 1 shows a schematic representation of a hydrodynamic retarder which can be used in a drive-train of a motor vehicle, in particular a commercial vehicle.

The retarder comprises a stator 'i and a rotor 2, each fitted with respective biades 3 and 4. As can also pe seen, the stator 1 and so too therefore its olades 3 are attached fixed to a housing 5 of the retarder, whereas the rotor 2 is mounted to rotate on a rotor shaft 6.

As a special feature the rotor 2 and the stator 'i are arranged radialiy relative to one another, with the rotor 2 running radialiy inside the stator 1. Thus, the biades 3 and 4 too are radially opposite one another with the olades 3 of the stater i clirected radiaiiy inward while, in Contrast, the blades 4 of the rotor 2 extend radially outward. in a manner whose principle is known to those familiar with the field, a braking torque is produced on the rotor 2 and hence on the rotor shaft 6 when a fluid present in a toroidal space 7 formed between the oiades 3 and 4 is picked up by the blades 4 of the rotor 2 and propellecl toward the blacles 3 of the stator 1. The fiuid then bounces off the blades 3 and returns to the blades 4 of the rotor 2, and this exerts a torque on the rotor 2 whose effect is to slow it down. in this case the fluid, for example oil or even water, is held permanentiy in the toroidal space 7 so that the braking torque acting on the rotor 2 is regulated hy means of an axially movable sleeve 8 of hoiiow-cyiindrical design which rotates together with the rotor 2. The sleeve 8 can be pushed by an actuator 9 against spring elements 10 and li, axially into the toroidai space 7 and radiaily between the blades 3 and 4. Thus, by means of the actuator 9, which in the present case is in the form of a hydraulicaliy actuated piston, in addition to a fully inserted position shown in Fig. 2 and a basic, initial position shown in Fig. 1 the sleeve can be moved to any interrnediate position, sö- Thus, when it ieaves the basic initiai position the sieeve 8 interrupts the tiow connection between the blades 3 and 4 so that as the axial displacement of the sieeve 8 increases, the braking torque acting on the rotor shaft 6 decreases.

When the sleeve 8 finally reaches the end position shown in Fig. 2, in which it has moved axiaily aii the way into the toroidal space 7, the talades 3 and 4 are compietely separated from one another so that no braking torque can any longer act on the rotor 2. i' Finally, Fig. 3 shows a schematic representation of an alternative embodiment of a hydrodynarnic retarder. The difference from the variant described above is that in this case, although a stator 12 is again coupied to a housing 13 in a rotationaily fixed manner, it can be moved axiaiiy relative thereto.

The housing 13 and the stator 12 can be connected, for exampie, by a splined shatt. Again, a rotor 14 on a rotor shaft 15 runs radially inside the stator 12. in addition, as in the previous variant a fixed quantity of fluid is heid between the stator 12 and the rotor 14, but with the difference from the variant described previousiy that the braking torque is this time adjusted by moving the stator 12 axiaily relative to the rotor 14 so that the biades 16 of the stator 12 aiso move axiaiiy reiative to the biades 17 of the rotor 14. in the position shown in Fig. 3, the biades 16 and 1"! compieteiy axialiy overiap, so that the fiuid picked up by the blades 17 is ali propeiied onto the biades 16, thereby producing the maximum braking torque on the rotor 14. On the other hand, if the stator 12 is moved to an end position - not shown here - in which the biades 16 no longer overiap at aii with the biades 17, then the iluid picked up by the biades 17 is no longer directed onto the biades 16 oi the stator 12 and accordingiy no braking torque is any ionger exerted on the rotor 14.

Again, the braking torque can be varied as desired by adopting positions intermediate between the two extreme positions described above. in this case the appropriate axiai position of the stator 12 is set in opposition to spring eiements 19 and 20 by means of an actuator 18, in the present case designed as an electromagnetic actuator. in a suitabie arrengement (net shown here) it is else possibie for the rater to be dispiaceci exieiiy reiative to the positionaiiy fixed stater.

By virtue of the design of e hytiredynamic reterder in eccerüanee With the inventien, eir iosses ef a retarder can be reduced very substentiaiiy in a simpie mâfiflflf. ÉIQOOMÛUI-bQUNW-Å ...à ...A ...z IV .x (JJ nu Jia 4. 01 .J U? ._\ M! ...x C20 _x (D fx) CD indexes Stater Rotor ââades Blades Hcusirrg Røtør shaft Tarøiüai sçace Sšeeve Actuator Spring eâement Spršng eiement Stater Housing Rotor Rotor shaft Biaües Biades Actuator Spršng eierrrent Spring eierrrent

Claims (10)

Ciaims

1. Hydrodynamic retarder, comprising a rotor (2; 14) and a stator (1; 12), characterized in that the rotor (2; 14) and the stator (1; 12) are arranged radiaiiy reiative to one another.

2. i-lydrodynamic retarder according to Claim 1, characterized in that the rotor (2; 14) and the stator (1; 12) are iitted with biades (3, 4; 16, 17), and means are provided by which a iluidic coupling between the biades (3, 4: 16, 17) can be interrupted.

3. Hydrodynamic retarder according to Ciaim 2, oharacterized in that the means consist in an axial mobiiity of the rotor (14) and the stator (12) reiative to one another.

4. Hydrodyitamic retarder according to Ciairn 2, characterized in that the means are in the form of at ieast one axiaiiy movahle sleeve (8), which can he inserted into a toroidal space formed between the rotor (2) and the stater (1).

5. Hydrodynarnic retarcler according to Ciaim 4, characterized in that the at ieast one sieeve (8) is coupied to the rotor (2) or the stator in a rotationaiiy fixed manner.

6. Hydrodynarnic retarder according to Ctaim 4, oharacterized in that the at least one sieeve (8) can be moved axiaiiy by means of an actuator (9) in opposition to at ieast one spring eiernent (1 O, 11).

7. i-iydrodynamic retarder according to Ciaím 2, characterized in that the fluidic coupiing can be eiiminated compieteiy. _1()..

8. Hydrodynamic retarder according to Ciainis3 and 7, charaoterized in that a quantity of fiuid is held permanently between the rotor (14) and the stator (12), and a braking torque acting on the rotor (i 2) can be adjusted by the axiai positioning of the rotor (i 4) and the stator (12) reiative to one another.

9. i-iydrodynamic retarder according to Ciaims 4 and 7, characterizec! in that a quantity of fiuid is heid permanentiy in the toroidai space (7), and a braking torque acting on the rotor (2) can be determined by the extent to which the at Eeast one sieeve (8) is inserted into the toroidat space.

10. Drive-train of a motor vehicie, which cornprises a hydrodynamic retarder according to any of Ciairns 1 to 9. _11-