DE102008034974B4 - Method for adjusting the power transmission of a hydrodynamic machine - Google Patents

Abstract

Method for setting the power transmission of a hydrodynamic machine, in particular a hydrodynamic retarder (1), with an external working medium circuit, in particular of a motor vehicle, with the following steps: 1.1 depending on a manually or automatically predetermined variable (12) for a power transmission to be set or a to be set In the hydrodynamic machine to be transmitted torque, a flow cross-section for working fluid, which flows into a formed by two paddle wheels working space (2) of the hydrodynamic engine and out of this, increased or decreased to the working fluid volume in the working space (2), by means of which and Torque is transmitted in the hydrodynamic machine, to vary; wherein 1.2 the change of the flow cross-section for working medium is effected by means of a control valve (3) which is actuated by means of a control device (4); characterized in that 1.3 the pressure (housing pressure pG, is) of the working medium in a space (5) outside the working space (2) and within a housing (6) which at least partially encloses the paddle wheels, wherein the housing pressure pG, is of the Changing the flow cross-section for working fluid by means of the control valve (3) is dependent, is measured and transmitted as an input variable of the control device (4); and 1.4 the control device (4) actuates the control valve (3) as a function of the transmitted housing pressure in the housing (6).

Description

The present invention relates to a method for adjusting the power transmission of a hydrodynamic machine, in particular a hydrodynamic retarder, with an external working medium circuit, in particular of a motor vehicle.

Hydrodynamic machines have a working space which can be filled with a working medium in order to transmit drive power or torque from a primary wheel of the hydrodynamic machine, also called an impeller, to a secondary wheel, also called a turbine wheel. In a hydrodynamic retarder, the turbine wheel is stationary, therefore also called stator, and allows for filled working space a delay of the impeller and in particular rotatably connected to the impeller shaft, for example, an indirectly connected to the wheels of a vehicle propeller shaft or transmission output shaft.

The transmitted from the impeller to the turbine wheel drive power or the transmitted torque - when forming the hydrodynamic machine as a hydrodynamic retarder, the braking torque - is dependent on the degree of filling of the working space of the hydrodynamic machine, which by the two paddle wheels, impeller and turbine or impeller and stator formed becomes. In particular, with increasing degree of filling, starting in a completely or largely deflated state or with a so-called minimum filling level up to a fully filled state, the transmitted power or the transmitted moment increases.

The setting of a certain degree of filling of the working space of a hydrodynamic machine and thus the control of the transmitted power or the transmitted torque can either by applying a superposition pressure to the working space supplied working fluid or by controlling the flow cross-section in a working fluid inlet or working fluid flow of the hydrodynamic machine by means of a control valve , in particular proportional valve. For applying a superposition pressure on the working medium of a hydrodynamic retarder, it is known, for example, to provide a reservoir for the working medium, in particular oil, with a membrane subjected to compressed air. The membrane separates the working medium from an air space, which is acted upon by means of a compressed air system, in particular vehicle compressed air system. By means of a pneumatic valve, the air pressure and thus the working medium pressure in the reservoir and thus also the overlay pressure acting on the working medium circuit can be varied.

According to an alternative embodiment, which is used for example in incorporated in a vehicle cooling circuit retarders, as the present invention according to one embodiment, a control valve, in particular proportional valve is provided in the external working medium circuit (cooling circuit), in particular in the flow direction of the working medium behind the retarder is provided at the retarder, and which increases or reduces a dynamic pressure at the retarder by varying the available for the working fluid flow cross-section. As the back pressure on the retarder outlet increases, the degree of filling of the working space increases. Also, this control valve or proportional valve is actuated by means of compressed air from a compressed air circuit. With increasing air pressure, which is caused by increasing opening of a pneumatic valve in the compressed air circuit, the free flow cross-section is reduced in the proportional valve and thus increases the back pressure at Retarderauslass.

The conventional embodiments of the control of the power transmission or the moment in a hydrodynamic machine, in particular the braking torque of a hydrodynamic retarder, have the disadvantage that a change in the working medium pressure in the external working medium circuit, for example by switching on or off of other units in the external working medium circuit or through other influences outside the control system, a deviation in the power transmission or the self-adjusting torque in the hydrodynamic machine may result from a desired default value. This is especially true in the cooling circuit, in particular vehicle cooling circuit, positioned hydrodynamic retarder, which are flowed through by the cooling medium of the cooling circuit as a working medium of the retarder. Here is the self-adjusting braking torque depends not only on the applied to the proportional valve pneumatic pressure, but also the back pressure of the vehicle cooling system. An independent of the back pressure of the cooling system adjustment of the braking torque is not possible with the existing control systems.

The publication DE 24 08 876 B2 discloses a hydrodynamic brake in which a partial flow of working fluid is diverted from the working space.

EP 1 632 690 A1 discloses in the control of a hydrodynamic coupling the Setting a desired pressure, which corresponds to the housing pressure of the hydrodynamic coupling, with the aid of a theoretical clutch model and a correction value derived therefrom and a pilot pressure. Thus, the correction value for the pressure to be set at the hydrodynamic clutch, which forms the pressure setpoint together with the pilot control pressure, is predetermined as a manipulated variable. This setpoint is then used to control the hydrodynamic coupling.

EP 1 234 129 B1 describes a method for speed control of a drive machine during a start-up process, wherein the rotational speed of the drive machine is adjusted in dependence on the power absorbed by a hydrodynamic coupling. For this purpose, a desired-actual comparison between the rotational speed of the engine and an actual speed takes place. From a resulting control difference, the degree of filling of the working space of the hydrodynamic coupling is changed during the starting process.

DE 101 40 220 A1 discloses a control unit connected to temperature and pressure sensors in a retarder circuit. These sensors are used to monitor temperature and retarder control pressure.

DE 44 08 350 C2 discloses a drive unit with simultaneous use of a hydrodynamic retarder and an engine brake. For this purpose, a continuously variable throttle valve is arranged in a discharge line, with which a stepless narrowing of the flow cross section of the line is possible.

On the further state of the art is on DE 10 2004 048 121 A1 directed. This publication discloses a method for adapting an operating characteristic of a hydrodynamic component-characterizing actual characteristic curve or actual characteristic diagram to a predefined or predefinable desired characteristic curve or desired characteristic diagram in the final acceptance of the hydrodynamic component.

The present invention has for its object to provide a method for adjusting the power transmission of a hydrodynamic machine, in particular the braking torque of a hydrodynamic retarder, with an external working fluid circuit, which also reliably causes the setting of a desired setpoint power transmission or braking torque when the external Working medium circuit is subject to pressure fluctuations that are caused by boundary conditions outside of a control system or outside the hydrodynamic machine.

The object of the invention is achieved by a method according to the independent claim. The dependent claims represent preferred embodiments of the invention.

Due to the fact that according to the invention, the pressure of the working medium in a space within a housing, referred to here case pressure, is measured and as the input variable of the control device, which actuates a control valve for setting or changing a flow cross section for the working medium, transmitted and taken into account in the adjustment of the flow cross-section is, one of the back pressure in the external working medium circuit, in particular in the cooling circuit of a vehicle, independent setting of the power transmission or transmitted by means of the working fluid in the working space torque is possible. Particularly advantageously, the measured value of the pressure, in particular by means of a pressure sensor, converted into an electrical, electronic or optical signal, and then the control device, which is designed in particular as an electrical or electronic control device transmitted.

• – In Abhängigkeit einer manuell oder automatisch vorgegebenen Größe für eine einzustellende Leistungsübertragung oder ein einzustellendes in der hydrodynamischen Maschine zu übertragendes Moment wird ein Strömungsquerschnitt für Arbeitsmedium, das in einen durch wenigstens zwei Schaufelräder – Pumpenrad und Turbinenrad oder Pumpenrad und Stator – gebildeten Arbeitsraum der hydrodynamischen Maschine und/oder aus diesem heraus strömt, vergrößert oder verringert, um das Arbeitsmediumvolumen im Arbeitsraum, mittels welchem Leistung und Drehmoment in der hydrodynamischen Maschine übertragen wird, zu variieren;
• – die Änderung des Strömungsquerschnittes für Arbeitsmedium wird mittels eines Regelventils bewirkt, das mittels einer Regeleinrichtung betätigt wird;
• – der Druck (Gehäusedruck p_G,ist) des Arbeitsmediums in einem Raum außerhalb des Arbeitsraumes und innerhalb eines Gehäuses, das die Schaufelräder wenigstens teilweise umschließt, wobei der Gehäusedruck p_G,ist von der Änderung des Strömungsquerschnittes für Arbeitsmedium mittels des Regelventils abhängig ist, wird gemessen und als Eingangsgröße der Regeleinrichtung übermittelt;
• – die Regeleinrichtung betätigt das Regelventil in Abhängigkeit des übermittelten Arbeitsmediumdruckes, das heißt des Gehäusedruckes p_G,ist.

The inventive method for adjusting the power transmission of a hydrodynamic machine, in particular a hydrodynamic retarder, with an external working medium circuit, in particular of a motor vehicle, comprises the following steps:

• As a function of a manually or automatically predetermined variable for a power transmission to be set or a torque to be set in the hydrodynamic machine, a flow cross-section for working medium is formed in a working space of the hydrodynamic machine formed by at least two impellers - impeller and turbine wheel or impeller and stator and / or flows out of it, increases or decreases to vary the working fluid volume in the working space, by means of which power and torque is transmitted in the hydrodynamic machine;
• - The change of the flow cross-section for working medium is effected by means of a control valve which is actuated by means of a control device;
• - the pressure (crank pressure p _{G, is)} of the working medium is dependent on the change in the flow cross section for the working medium by means of the control valve in a space outside the working area and within a housing, which encloses the blade wheels at least partially, wherein the housing pressure p _G, becomes measured and transmitted as input to the control device;
• - The control device actuates the control valve in response to the transmitted working fluid pressure, that is, the housing pressure p _{G, is} .

When using the method according to the invention for a vehicle drive train, manually presetting the variable means, for example, that the driver sets the amount of power transmission, in particular of the braking torque of a hydrodynamic retarder, by means of a selector lever by hand. An automatic specification of the size can be done for example by a cruise control system of the vehicle.

The control valve is advantageously designed as a hydraulic valve, which is flowed through by the working medium, which in particular is at the same time the cooling medium of a vehicle cooling circuit.

The control device advantageously comprises a housing pressure regulator and a control pressure regulator. By means of the housing pressure regulator, the housing pressure is at least indirectly regulated, and by means of the control pressure regulator, a control pressure is at least indirectly regulated. By means of the control pressure, the control valve is actuated. The control pressure is for example an air pressure in a compressed air system, in particular vehicle compressed air system, which is adjusted by means of a pneumatic control pressure valve, in particular regulated.

It is particularly advantageous from the manually or automatically predetermined size for the adjusted power transmission or the torque to be transmitted by means of the hydrodynamic machine, at a retarder the braking torque, a setpoint p _{G, is determined} for the housing pressure and with the measured housing pressure p _{G, is} compared. For determination of the setpoint value p _G, the rotational speed of an impeller, in particular of the impeller, of the hydrodynamic machine or a speed correlating therewith, for example _{, should be selected} for the housing pressure in addition to the manually or automatically predetermined variable for the power transmission to be set or the torque to be set Vehicle with a secondary retarder of the PTO shaft, considered.

The determination of the desired value p _{G, should be made} for the case pressure in particular from stored in the control device characteristics.

According to one embodiment, in the control device between the measured actual value of the housing pressure p _{G, is} and the setpoint p _G, a control difference is determined and fed to the housing pressure regulator as an input variable. The case pressure controller then determines, for example, from the control difference supplied to it a manipulated variable and transmits this as an input to the control pressure regulator. The control pressure regulator can then determine from the manipulated variable transmitted to it a desired value for the control pressure which acts on the control valve or by means of which the control valve is actuated. This determination can in turn be made advantageously by means stored in the control device characteristics.

Particularly advantageously, the determined setpoint value for the control pressure p _{y, soll is} compared with a measured or calculated actual value of the control pressure p _y, and a difference value or a control difference is determined from the two variables. This control difference between the desired value and the actual value of the control pressure can then be supplied to the control pressure regulator, which advantageously adjusts the valve position of a control pressure valve and thus regulates the control pressure. The control pressure valve is advantageously designed as a proportional valve and varies by opening and closing a flow cross-section for a control medium, in particular air, from a control pressure source, the control pressure.

This control pressure is then applied to the control valve which, depending on the control pressure applied to it, changes the flow cross section for the working medium and thus the degree of filling of the hydrodynamic machine, which, in addition to a change in the power transmission or the torque transmitted, also leads to a change in the casing pressure.

A regulation of the housing pressure, as described, causes a hysteresis in the adjustment of the working medium pressure in the working space of the hydrodynamic machine and thus the degree of filling of the working space of the hydrodynamic machine is avoided and exactly that power transmission - in a retarder the braking torque - is set, which / which was specified manually or automatically.

The housing pressure is thus regulated particularly advantageously in a first control loop, referred to herein as a superimposed control loop, and in a second control loop, referred to herein as a subordinate control loop or a cascade, the control pressure is regulated, by means of which the control valve is acted upon in the working medium flow. The superimposed control loop, also called outer control loop, in which the measured casing pressure p _{G, is} advantageously recirculated and a control difference between the desired value p _{G, soll} and the actual value p _{G, is} formed can, if so desired, be less frequently be passed through or have a lower clock frequency, as the lower-level control loop (the cascade), which can also be referred to as inner loop and advantageously the return of the measured control pressure p _y, and the formation of a control difference from the setpoint p _{y, soll} and the actual value p _{y , is} comprised of the control pressure. In this way, an overshoot of the valve piston of the control valve, in particular when it is acted upon on a first side with the control pressure and applied on a second side opposite to the first side with the pressure of the working medium in the external working medium circuit or at the outlet of the working medium from the hydrodynamic machine, avoided be, which always threatens if by a filling operation of the working space of the hydrodynamic machine when switching on the hydrodynamic machine, the working fluid pressure at the outlet of the hydrodynamic machine or behind the hydrodynamic machine, which acts on the valve piston of the control valve, compared to the control pressure is delayed.

The control valve may for example have both a directional control function and release upon admission with a control pressure, in particular pneumatic pressure, an inlet for working fluid in the hydrodynamic machine, as well as have a control valve function, that is, regulate the working fluid pressure at the outlet of the hydrodynamic machine by adjusting a back pressure. Particularly advantageously, the control valve blocks the inlet of the hydrodynamic machine substantially or completely, as long as no control pressure or a control pressure below a predetermined switch-on threshold applied to him.

As an alternative to the actuation of the control valve by means of a control pressure, it is also possible to actuate the control valve, in particular its valve piston, by means of a magnetic force. In one embodiment with a superimposed housing pressure control loop and a subordinate control variable control circuit, a valve current could then be used as the control variable, which causes a corresponding magnetic force in the control valve for adjusting the valve piston.

Accordingly, instead of a control pressure regulator, a control current regulator would then be used.

Particularly preferably, the hydrodynamic machine is designed as a hydrodynamic oil or water retarder. In addition to an application of a method according to the invention, wherein the hydrodynamic machine is integrated in a drive train of a vehicle, an application in industrial plants is conceivable.

Particularly preferably, the hydrodynamic machine has pressure sensors, in particular sensors, which preferably generate electrical signals. Such passive or active components may be arranged in, on or in the region of the housing and / or in the spaces enclosed by the housing of the hydrodynamic machine. Also in the working medium circuit of the hydrodynamic machine sensors may be provided.

Also, sensors for speed and / or torque detection, for example, the primary and / or the secondary wheel or waves that are at least indirectly in driving connection with primary and / or secondary, such as a transmission shaft of a vehicle or an industrial plant, may be provided ,

The control device may for example be integral with an existing vehicle electronics - when using the hydrodynamic machine in a motor vehicle - or separately.

Particularly advantageously, the housing pressure regulator is designed as an I controller or PI controller. The control pressure regulator can in this case be designed, for example, as a P controller.

Preferably, when applying the method according to the invention for controlling the braking torque of a hydrodynamic retarder in a vehicle when initiating a braking process, especially from fast driving first, in particular by the vehicle electronics, for example, the retarder ECU (electronic control unit), the target value of the housing pressure p _{G, should} and the setpoint of the control pressure p _{y, should be} specified from stored characteristic curves. For example, an automatic or predetermined by the driver setpoint for a braking or deceleration request from a central vehicle electronics, in particular in the form of a moment to be communicated to the retarder ECU. There is then according to one embodiment, a sole control of the control pressure p _{y, is} on p _{y, soll} . If the control difference between p _y, and p _{y, should} within a predetermined range and this range is maintained for a predetermined period of time, there is a switch to a sole control of the housing pressure p _{G, should} . As an alternative to the downstream sole control of the housing pressure, the inner control loop of the control pressure can also be passed through the outer control loop at all times or at predetermined intervals.

The invention will now be explained by way of example with reference to embodiments and the accompanying figures.

Show it:

1 a schematic representation of a arranged in a motor vehicle drive train retarder;

2 a first embodiment of a hydrodynamic retarder according to the invention in an axial section;

3 a second embodiment of a hydrodynamic retarder according to the invention in an axial section;

4 a schematic control loop of a method according to the invention.

In 1 is a vehicle powertrain with a working fluid / cooling circuit 18 shown. Here is a hydrodynamic retarder 1 provided, which in the present case is designed as a water retarder, so that its working medium simultaneously represents the cooling medium of the vehicle. In the flow direction behind the retarder seen the following components in the cooling circuit 18 arranged: a control valve 3 , the confluence of a reservoir 15 , a heat exchanger 17 , a coolant pump 16 and a switch-on valve 27 , In the flow direction in the cooling circuit 18 parallel to the hydrodynamic retarder 1 is an internal combustion engine 13 arranged. Of course it would also be possible to use the hydrodynamic retarder 1 and the internal combustion engine 13 to be arranged in series with each other. Furthermore, the control valve could 3 and the on-off valve 27 be combined to a common combination valve.

The hydrodynamic retarder 1 is in the present case designed as a secondary retarder, that is, it is on a transmission output shaft 19 , in this case a power take-off, a transmission 14 arranged. The retarder 1 has a primary wheel 24 , which with the transmission output shaft 19 rotatable, on. Furthermore, the retarder includes 1 a secondary wheel 25 which is stationary in the present case, for example forms part of a retarder housing.

In the cooling circuit 18 is present in the flow direction behind the retarder 1 a control valve 3 for setting a predetermined working medium pressure in the working space of the hydrodynamic retarder 1 provided to regulate the degree of filling of the working space with working fluid via this pressure setting. The higher the set pressure in the working area, the more braking torque is generated by the retarder 1 made available. In the present case, the control valve 3 from a control pressure valve 9 , which is designed in this case as a pneumatic valve, driven. For this purpose, air pressure in a pneumatic pressure vessel 23 or a compressed air system. The control pressure valve 9 can for example be designed as a proportional valve, continuous valve as servo valve.

By pressing a brake pedal 22 or other Aktuartors, such as a selector lever (not shown), a braking operation is initiated, wherein the flow cross-section of the control pressure valve 9 is increased, allowing compressed air from the pressure vessel 23 or a compressed air system, the control valve 3 subjected to increasing pressure, at the same time the on-off valve 27 also by pressurization by means of compressed air from the pressure vessel 23 or the compressed air system is switched into its passage position and working fluid from the cooling circuit 18 in the retarder 1 arrives. This will be the primary wheel 24 , with this the transmission output shaft 19 , the PTO shaft 20 and finally the wheels 21 by forming a hydrodynamic circuit in the working space of the retarder between the primary wheel 24 and the secondary wheel 25 delayed. The position of the brake pedal 22 or other actuator can be detected for example by a vehicle electronics or a control device and to control the control valve 3 or control pressure valve 9 to be used.

In the 2 is a first embodiment of a hydrodynamic retarder according to the invention 1 shown. The retarder 1 includes a primary wheel 24 as well as a secondary wheel 25 , which are bladed and a common work space 2 form. Present are primary wheel 24 , Secondary wheel 25 and workspace 2 from a housing 6 enclosed. Inside the case 6 are more rooms 5 formed, which extend axially adjacent to the working space. The rooms 5 serve as inlet and outlet for working medium, wherein present over the radially inner space 5 the working medium in the working space 2 and the radially outer space 5 from the workroom 2 is passed out.

Radial outside the workspace 2 and in the present case radially outside of the secondary wheel 25 is a sensor 26 provided, which in the housing 6 is arranged. The sensor 26 is designed as a pressure sensor and thus detects the pressure of the centrifugal forces due to centrifugal forces from the working space 2 ejected working medium. The from the sensor 26 detected measured values are transmitted to a control device (not shown) and / or to an electronic unit, by means of which a control pressure valve and via this a control valve, for example corresponding to the valves 3 and 9 in the 1 , be operated.

The 3 shows the same object as in 2 shown, only is the sensor 26 in another place in the case 6 arranged. This is located in the immediate vicinity of the primary wheel 24 and is present in the area of the outlet, here radially from the outside into the outlet (space 5 ), the hydrodynamic retarder 1 arranged.

In the embodiments according to 2 and 3 would also be a variety of sensors 26 conceivable, which in particular in, on or in the region of the housing 6 are arranged. These sensors are used to measure the casing pressure P _G, and thus used to control or regulate the power transmission according to a method according to the invention.

In the 4 is symbolically illustrated a control circuit for adjusting the power transmission of a hydrodynamic machine in a working medium circuit. The control device 4 become a manually or automatically predetermined size 12 , For example, the target braking torque of a hydrodynamic retarder, as well as a measured or calculated size 28 For example, the speed of a propeller shaft or other proportional to the speed of the impeller of the retarder speed, and the actual value of the housing pressure p _G, (see, for example, the sensors 26 in the 2 and 3 ). Off in the control room 4 stored characteristic curves 11 will be out of size 12 and the size 28 a setpoint for the housing pressure p _{G, should be} determined. From the setpoint of the housing pressure p _{G, should} and the actual value of the housing pressure p _G, a control difference is formed and the housing pressure regulator 7 fed. The housing pressure regulator 7 determines a manipulated variable from the control difference 29 from which by means of a stored characteristic curve (or a plurality thereof), a desired value for the control pressure p _{y, soll is} determined. From the setpoint for the control pressure p _{y, soll} and a measured or calculated actual value of the control pressure p _y, in turn, a control difference is formed and the control pressure regulator 8th fed. The control pressure regulator 8th actuated, for example via an electric current as a manipulated variable, the control pressure valve 9 , whereby, depending on the extent of the operation, the actual value of the control pressure p _{y, is} more or less changed. The control pressure (p _{y, is} ) acts on the control valve 3 , which in turn the pressure of the working medium in the hydrodynamic retarder 1 or the degree of filling of the working space in the hydrodynamic retarder 1 is set, from which the housing return p _G, in turn _{, is} dependent.

LIST OF REFERENCE NUMBERS

1

hydrodynamic retarder

2

working space

3

control valve

4

control device

5

room

6

casing

7

Body regulator

8th

Control pressure regulator

9

Control pressure valve

10

curve

11

curve

12

manually or automatically preset size

13

Internal combustion engine

14

transmission

15

oilcontainer

16

Coolant pump

17

heat exchangers

18

Working-medium / cooling circuit

19

Gearbox output shaft

20

propeller shaft

21

bikes

22

brake pedal

23

pneumatic pressure vessel

24

primary wheel

25

secondary

26

sensor

27

On-off valve

28

measurand

29

manipulated variable

Claims (9)

Method for adjusting the power transmission of a hydrodynamic machine, in particular a hydrodynamic retarder ( 1 ), with an external working medium circuit, in particular a motor vehicle, with the following steps: 1.1 depending on a manually or automatically predetermined size ( 12 ) for a power transmission to be set or a torque to be set to be transmitted in the hydrodynamic machine becomes a flow cross-section for working medium, which is introduced into a working space formed by two impellers (FIG. 2 ) flows from the hydrodynamic machine and out of this, increases or decreases to the working fluid volume in the working space ( 2 ), by means of which power and torque is transmitted in the hydrodynamic machine, to vary; wherein 1.2 the change of the flow cross-section for working medium by means of a control valve ( 3 ) is effected by means of a control device ( 4 ) is actuated; characterized in that 1.3 is the pressure (housing pressure p _G, ) of the working medium in a room ( 5 ) outside the workroom ( 2 ) and within a housing ( 6 ), which encloses the paddle wheels at least partially, wherein the housing pressure p _{G, is} of the change of the flow cross-section for working fluid by means of the control valve ( 3 ) is dependent, is measured and as an input variable of the control device ( 4 ) is transmitted; and 1.4 the control device ( 4 ) the control valve ( 3 ) as a function of the transmitted housing pressure in the housing ( 6 ). Method according to claim 1, characterized in that the control device ( 4 ) a housing pressure regulator ( 7 ) and a control pressure regulator ( 8th ), and that by means of the housing pressure regulator ( 7 ) at least indirectly, the housing pressure and by means of the control pressure regulator ( 8th ) a control pressure for the at least indirect actuation of the control valve ( 3 ) be managed. Method according to claim 2, characterized in that the control device ( 4 ) a setpoint p _{G, should be} for the housing pressure in dependence of a manually or automatically predetermined size ( 12 ) for the power transmission to be set or the torque to be set, and in particular as a function of the rotational speed of an impeller or a shaft driving the impeller. Method according to claim 3, characterized in that in the control device ( 4 ) Characteristic curves are stored, from which the desired value p _{G, soll} for the housing pressure in dependence of the predetermined size ( 12 ) is determined for the power transmission to be set or the moment to be set. Method according to one of claims 2 to 4, characterized in that in the control device ( 4 ) between the actual value of the housing pressure p _{G, is} and the setpoint p _G, a control difference is determined and the housing pressure regulator ( 7 ) and one of the control device ( 4 ) and in particular the housing pressure regulator ( 7 ) determined manipulated variable as input to the control pressure regulator ( 8th ) is transmitted. A method according to claim 5, characterized in that from the of the housing pressure regulator ( 7 ), a desired value for the control pressure p _{y, soll} , which on the control valve ( 3 ), is determined, in particular by means of in the control device ( 4 ) stored characteristic curves, and between a measured or calculated actual value of the control pressure p _y, and the setpoint p _{y, should} the control pressure, a control difference is determined and the control pressure regulator ( 8th ) is supplied. Method according to claim 6, characterized in that the control pressure regulator ( 8th ) the valve position of a control pressure valve ( 9 ), which is designed in particular as a proportional control valve and which varies the control pressure by opening and closing a flow cross-section for a control medium, in particular air, from a control pressure source adjusts. A method according to claim 6 or 7, characterized in that the return of the measured housing pressure p _G, and the formation of the control difference from the setpoint p _{G, soll} and the actual value p _{G, is} in a first control loop and the return of the measured Control pressure p _y, and is the formation of a control difference from the setpoint p _{y, soll} and the actual value p _y, the control pressure is in a second control loop. A method according to claim 8, characterized in that the first control loop is superimposed on the second control loop and has a lower clock frequency than the second control loop.

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