DE102011010403A1 - Cooling system has drive motor or another aggregate to be cooled by cooling medium and cooling medium circuit for conducting cooling medium, where hydrodynamic machine is provided with rotating blade wheel - Google Patents

Abstract

The cooling system has a drive motor (1) or another aggregate to be cooled by a cooling medium and a cooling medium circuit (2) for conducting the cooling medium. A hydrodynamic machine (3) is provided with a rotating blade wheel, another rotating or stationary blade wheel and a drive shaft (8), which is sealed by a seal (9) against the housing. The seal comprises a collection chamber (10) for receiving the cooling medium. An independent claim is also included for a method for preventing leakage losses of a seal of a hydrodynamic machine.

Description

The present invention relates to a cooling system, comprising a drive motor to be cooled by means of a cooling medium or another unit, a cooling medium circuit leading the cooling medium and a hydrodynamic machine, in detail according to the preamble of claim 1.

Hydrodynamic machines have a working space which can be filled with a working medium in order to transmit drive power or torque from a first revolving impeller, also called an impeller, to a second revolving impeller of the hydrodynamic machine, also called a turbine wheel. When forming the hydrodynamic machine as hydrodynamic retarder, the second impeller rotates counter to the direction of rotation of the first impeller or is stationary and is therefore also called stator.

The transmitted from the first impeller to the second impeller drive power or the transmitted torque is dependent on the degree of filling of the working space of the hydrodynamic machine, which is formed by the two paddle wheels. In particular, with increasing degree of filling, starting in a completely or largely deflated state (idling) up to a fully filled state, the transmitted power or the transmitted torque increases. By setting a certain degree of filling of the working space with working medium, the power transmission of the hydrodynamic machine can thus be controlled.

As a working medium for such hydrodynamic machines in particular oil, water or a water mixture comes into consideration. In the latter two cases, the cooling medium of the cooling system or of the cooling medium circuit is at the same time the working medium of the hydrodynamic machine. Since the hydrodynamic machine has rotating and stationary components or components rotating at different speeds relative to one another, seals between these components are necessary in order to prevent an undesirable escape of working medium into the environment. Such seals are arranged, for example, between a stationary housing of the hydrodynamic machine and a rotating shaft, for example a drive shaft of the first or second impeller.

The patent DE 10 2006 054 615 B3 describes a cooling system with a drive motor and a hydrodynamic machine, which has a means of cooling medium permanently cooled and / or lubricated seal. In this case, during the operation of the drive motor constantly cooling medium from the cooling medium circuit, in particular from a point in the flow direction of the cooling medium seen immediately before or behind the hydrodynamic machine, branched off. This branched cooling medium is introduced via a cooling medium supply to the seal. After the cooling medium has passed through the seal or past the seal, it is returned via a cooling medium discharge back into the cooling medium circuit immediately before or in the region of a cooling medium pump. Due to the fact that the cooling medium discharge of the seal is connected to a location of constantly low pressure levels of the cooling medium circuit (suction side of the cooling medium pump), a pressure difference results over the seal, which ensures a permanent flow through the seal. This constant flow is therefore necessary to ensure sufficient cooling or lubrication of the seal during operation of the hydrodynamic machine.

A disadvantage of these seals, however, is that they tend to leaks. Efforts have therefore been made in practice to improve these seals. However, it has been shown that there are still problems with the tightness, in particular in a hydrodynamic machine designed as a hydrodynamic retarder whose working medium is water or a water mixture, in particular the coolant of a vehicle cooling circuit. Although, in this case, leakage of the water is not harmful to the environment. However, this undesirable loss of cooling medium means that the cooling system must frequently be topped up with water between service intervals when larger leaks of the seal occur. This is unsatisfactory for the user of such a motor vehicle with such a cooling system and a hydrodynamic machine, in particular a hydrodynamic retarder.

The present invention has for its object to provide a cooling system with a hydrodynamic machine, in particular a hydrodynamic retarder whose drive shaft is particularly reliable and permanently sealed against the housing of the hydrodynamic machine to avoid unwanted leakage of working fluid from the hydrodynamic machine. Under drive shaft is to understand any form of a wave, whether hollow shaft or solid shaft or disc or annular shaft, which allows a drive at least one paddle wheel of the hydrodynamic machine.

The object of the invention is achieved by a cooling system with a hydrodynamic machine and a method according to the independent claims. The dependent claims indicate advantageous and particularly expedient embodiments of the invention.

The cooling system according to the invention comprises a drive motor to be cooled by means of a cooling medium or another unit to be cooled with the cooling medium, a cooling medium circuit leading the cooling medium, and a hydrodynamic machine having a first revolving impeller and a second likewise revolving or stationary impeller, which can be filled with working medium form filled working space to transfer torque hydrodynamically from the first paddle wheel to the second paddle wheel. In this case, the hydrodynamic machine comprises a housing which, together with one of the two paddle wheels, encloses the other paddle wheel or encloses both paddle wheels. The hydrodynamic machine has a drive shaft for mechanically driving the first or second impeller. The drive shaft is sealed by a seal against the housing.

According to the invention, the seal comprises a collecting space for receiving cooling medium in order to prevent leakage of cooling medium between the drive shaft and the housing. The collecting space is connected in a flow-conducting manner via a leakage line for returning the cooling medium located in the collecting space to the cooling medium circuit. In the leakage line, a check valve is arranged, which blocks the cooling medium flow in the direction of the collecting space. The collecting space does not necessarily have to be arranged inside the seal or in the region of the shaft sealed by means of the seal, but it can also be connected to the seal, in particular a sealing gap, by the working medium-conducting connection and be positioned inside or even outside the hydrodynamic machine.

According to a first embodiment, the leakage line terminates in a point of the cooling medium circuit, in particular within the hydrodynamic machine, which at times has a lower pressure level compared to the collecting space, so that the check valve opens and cooling medium is discharged from the collecting space, and temporarily compared to the collecting space has a higher pressure level, so that the check valve closes and accumulating cooling medium accumulates in the plenum. This results over the leakage line, in particular between the plenum and the leakage line, a pressure difference, which is used with the check valve open to "expelling" the collected in the collecting space leakage amount of cooling medium. The driving pressure difference advantageously corresponds to the largest pressure difference occurring temporarily in the cooling medium circuit, but a smaller pressure difference may also suffice. In particular, the point in which the leakage line opens in the cooling medium circuit, viewed in the flow direction of the cooling medium behind a vehicle radiator, be arranged behind the hydrodynamic machine itself or in front of a cooling medium pump. If, for example, the cooling medium of the cooling medium circuit is at the same time the working medium of the hydrodynamic machine, the lower pressure level at the said point in the cooling medium circuit always occurs when the hydrodynamic machine is switched on. The lower pressure level results from the fact that a part of the working fluid is withdrawn from the cooling medium circuit and fed to the working space of the hydrodynamic machine for torque transmission. In this case, the lower pressure level alone be sufficient to dissipate the accumulated amount of leakage from the plenum in the cooling medium circuit.

According to a second embodiment, the check valve is viewed in the flow direction of the cooling medium upstream of a float valve and arranged in particular in the collecting space, which releases or blocks the flow cross section for cooling medium in the direction of the check valve in dependence on the cooling medium level in the collecting space. In this case, the float valve is designed such that it blocks the opening cross-section in the direction of the check valve in a substantially coolant-empty collecting space, so that existing air in the collecting chamber is not drawn into the cooling medium circuit.

Preferably, the seal additionally has a cooling medium supply for cooling and / or lubricating the seal as well as a cooling medium discharge for returning the cooling medium into the cooling medium circuit, wherein the cooling medium supply and the cooling medium discharge are flowed through substantially permanently. Thus, the leakage line is provided in addition to the cooling medium discharge and cooling medium supply.

Advantageously, the collecting space associated with an air separator, which is arranged in particular in the flow direction of the cooling medium in front of the check valve. As a result, the collected leakage amount of cooling medium can be returned to the cooling medium circuit with exclusion of air. This prevents that air transported by the cooling medium collects, for example in the vehicle radiator, where it interferes with the heat transfer and leads to a reduction in the cooling capacity of the cooling system.

According to a third embodiment, the air separator is designed as a displacement device, by means of which the cooling medium receiving volume of the plenum is impulsively reduced, wherein the collecting space seen in the flow direction of the displaced cooling medium, a throttle point is connected in parallel to the leakage line.

The displacement device preferably comprises a displaceable piston or a deformable membrane which at least partially limits the volume of the collecting space and can be acted upon by a control pressure for its displacement or deformation.

Preferably, the seal is a mechanical seal. For this purpose, the mechanical seal may comprise at least a first sliding ring and a second sliding ring, which are arranged concentrically surrounding each other, for example in the radial direction and which each have a sealing surface which seal a sealing gap extending in the radial direction to the drive shaft together with a counter element. Here, a cooling medium channel opens in the radial direction between the two sealing surfaces in the mechanical seal in order to cool and / or lubricate the two sealing surfaces with cooling medium. The cooling medium channel is charged with cooling medium from the cooling medium supply, so that the cooling medium can flow through this cooling medium channel and can reach the two sealing surfaces via the mouth of the cooling medium channel. The cooling medium, after it has cooled and / or lubricated the two sealing surfaces, can be removed from the mechanical seal and, in particular, from the hydrodynamic machine by means of the cooling medium discharge.

• – Auffangen einer aus der Dichtung austretenden Leckagemenge an Kühlmedium in einem Sammelraum;
• – intermittierendes Entleeren des Sammelraums durch Zurückführen der aufgefangenen Leckagemenge in den Kühlmediumkreislauf.

A method according to the invention for preventing leakage losses at a seal of a hydrodynamic machine, wherein the seal of the hydrodynamic machine for cooling and / or lubrication is connected to a cooling medium circuit of a cooling system, comprises the following steps:

• - Collecting a leaking from the seal leakage amount of cooling medium in a plenum;
• - Intermittent emptying of the collecting space by returning the collected leakage amount in the cooling medium circuit.

The invention will now be explained by way of example with reference to exemplary embodiments.

Hereby show:

1 a schematic representation of a cooling system with a hydrodynamic machine according to a first embodiment;

2a - 2c a detail of a connected to the cooling system hydrodynamic retarder in axial section through its longitudinal axis according to a second embodiment;

3 a schematic representation of the operating principle of a leakage return of the lubricated by the cooling / cooled seal according to a third embodiment;

4a . 4b in each case an axial section through a connected to the cooling system leakage valve according to the third embodiment.

In the 1 is schematically illustrated a cooling system of a motor vehicle, comprising a cooling medium leading the cooling medium 2 , In the cooling medium circuit 2 the following components are arranged one behind the other in the flow direction: a drive motor to be cooled 1 , a thermostatic valve 27 , a vehicle radiator 17 , the mouth of a first connecting line to a surge tank 12 , a cooling medium pump 11 , a first switching valve 28 and the mouth of a second connecting line to the surge tank 12 , Parallel to the vehicle radiator 17 a bypass is provided for bypassing the same.

By means of the first switching valve 28 can cooling medium in a side branch of the cooling medium circuit 2 be branched, in which a hydrodynamic machine 3 which is present as a hydrodynamic retarder, comprising a rotating first impeller 4 and a stationary second paddle wheel 5 forming a toroidal working space (not shown in detail) is formed. In the present case, the hydrodynamic retarder in the flow direction of the cooling medium is a switching valve 29 downstream, before the cooling medium back into the main branch of the cooling medium circuit 2 flows. It could both switching valves 28 . 29 combined to a common valve (combination valve).

In the present case, the hydrodynamic retarder is designed as a primary retarder, that is, it is dependent on the speed of a drive shaft 8th of the drive motor 1 driven. Of course, it would be conceivable to carry out the hydrodynamic retarder as a secondary retarder. In this case, it would then be driven in dependence on the driving speed of the vehicle, for example the rotational speed of a drive shaft connected to vehicle wheels.

The hydrodynamic retarder includes a housing (not shown in detail) against which the drive shaft 8th by means of the seal shown only schematically 9 is sealed. The present is the seal 9 designed as a mechanical seal. The seal 9 is to its cooling / lubrication via a cooling medium supply (not shown) permanently with cooling medium from the cooling circuit 2 supplied, wherein the supplied via the cooling medium supply cooling medium permanently via a cooling medium discharge (not shown) in the cooling medium circuit 2 is returned.

In addition to the cooling medium drain (not shown), one is removed from the seal 9 escaping leakage quantity of cooling medium via a leakage inlet 21 in a collection room 10 guided and collected there. The outlet side is the collection space 10 via a leakage line 13 with the cooling medium circuit 2 connected. This is one end of the leakage line 13 with the collection room 10 and the other end with a point of temporarily low pressure levels of the cooling medium circuit 2 connected. In this case, temporarily low pressure level means that this does not have to occur permanently at this point in the cooling circuit, but, for example, inter alia then or only when the hydrodynamic retarder is activated. In this case, a certain amount of cooling medium through the retarder from the main branch of the cooling medium circuit 2 removed and led into the working space of the retarder. As a result, the pressure level drops in the main branch of the cooling medium circuit 2 , in particular between the vehicle radiator 17 and the cooling medium pump 11 for a short time. This pressure reduction thus acts on the end of the leakage line 13 , which causes the leakage line 13 provided check valve 14 opens and the in the collection room 10 Accumulated amount of cooling medium expires or is sucked in particular, back into the main branch of the cooling medium circuit 2 , Due to the pressure difference occurring, therefore, the plenum 10 are drained automatically from time to time without providing an additional pump or control device, with emptying is also a partial emptying and not just a complete emptying to understand.

If now the pressure level at the discharge point of the leakage line 13 in the main branch of the cooling medium circuit 2 on the normal or in the off state of the retarder prevailing pressure rises again, closes the check valve 14 and from the collection room 10 can no other cooling medium in the cooling medium circuit 2 flow away. This prevents at the same time that in the collecting space 10 air in the cooling medium circuit 2 emptied, due to a too long emptying of the collecting space 10 ,

The intermittent opening of the check valve 14 or the intermittent emptying of the collecting space 10 arises solely due to the pressure fluctuations at the discharge point of the leakage line 13 in the cooling medium circuit 2 one.

The return of the collected leakage quantity back into the cooling medium circuit 2 also has the advantage that in this way in the cooling medium circuit 2 occurring pressure peaks can be significantly reduced. Thus, the risk of damage to the cooling medium circuit 2 arranged components, such as the cooling medium pump 11 be minimized in particular by cavitation.

The 2a to 2c show a second embodiment of the present invention. This is part of a hydrodynamic machine 3 shown in an axial section through its longitudinal axis. Like components are denoted by the same reference numerals as in FIG 1 represented, provided.

As you can see from the figures, is the collection space 10 a float valve 15 assigned. In the present case is the collection room 10 the float valve 15 out. This is in the collection room 10 a valve body introduced here in the form of a ball, but other shapes for the valve body can be selected. The collection room 10 is here directly below the seal, not shown. He is over a leakage inflow 21 , here a hole, with the seal 9 fluidically connected. plenum 10 , Float valve 15 and check valve 14 can as shown on the case 7 the hydrodynamic machine 3 attached or be integral with this.

In the present case, the leakage line opens 13 but not directly in the cooling medium circuit 2 but in the area of the workspace 6 the hydrodynamic machine 3 , However, another position could be the mouth of the leakage line 13 in the cooling medium circuit 2 to get voted.

2a shows the valve position of the check valve 14 at the time, to the workroom 6 a relatively low pressure level prevails. This is due to the fact that when not activated hydrodynamic retarder (idle or non-braking operation), ie completely or largely emptied state of the working space 6 , Based on the environment, a negative pressure in the work space 6 formed. Because of this, the check valve gives 14 the opening cross-section for cooling medium in the working space 6 free. Thus, this can be done via the leakage inlet 11 from the seal 9 leaked cooling medium, which is in the plenum 10 accumulated over the leakage line 13 in which the check valve 14 is arranged in the working space 6 and from this back into the cooling medium circuit 2 flow out.

Now increases the pressure in the work area 6 on, so locks, as in the 2 B shown is the check valve 14 the opening cross-section of the leakage line 13 and not only prevents further outflow of cooling medium from the plenum 10 , but also a return of cooling medium from the work dream 6 in the seal 9 , This is the case with activated hydrodynamic retarder (braking operation). There is in the workroom 6 overpressure against the environment. The collection room 10 is thus, as already stated, always emptied only when in the work area 6 a low pressure level prevails.

Now falls, as in 2c shown, the cooling medium level in the plenum 10 by emptying the same far enough that undesirable air from the seal 9 in the direction of the workspace 6 and further into the cooling medium circuit 2 would flow, so the ball of the float valve sinks 15 so far down that they come together with a valve seat of the float valve 15 the opening cross-section in the leakage line 13 shuts off. This ensures that at substantially cooling medium empty plenum 10 and at low pressure level in the workspace 6 no air from the collection room 10 in the workroom 6 flows, which could lead to an undesirable increase in pressure in this, and / or in the cooling medium circuit 2 is registered (the latter in particular at a mouth of the leakage line 13 in the cooling medium circuit 2 ).

The 3 shows a schematic representation of another embodiment according to the invention a connected to the cooling system leakage return of the seal 9 , Again, substantially the same components are provided with the same reference numerals.

In the present case, a piston displaceable in a piston space in the axial direction is provided 24 arranged, which for its displacement via a control pressure port 22 , here formed by a piston rod, is actuated. The piston 24 divides the piston chamber into two subspaces, one of which is the collecting space 10 represents. In the collection room 10 lead the leakage feed 21 and a leak 23 , In the present case, the leakage feed 21 in the confluence with the collection room 10 a throttle point 32 with a significantly smaller flow cross-section than the leakage process 23 or to the leakage process 23 subsequent leakage line 13 on.

Will the piston 24 now by means of the control pressure connection 22 actuated in pulses, so is the volume of the plenum 10 suddenly reduced. Located in the collection room 10 essentially only air, so this is compressed. The compressed air is via the throttle 32 in the leakage inlet 21 towards the seal 9 repressed. By having the air through the throttle 32 flows out, can be in the collection room 10 do not build up enough pressure around the check valve 14 in the leakage line 13 to open. The check valve 14 thus remains closed and there is no air in the leakage line 13 repressed.

If, however, cooling medium in the plenum 10 This can not be due to its incompressibility through the throttle point 32 escape when the piston 24 is moved impulsively and the volume of the collection space 10 suddenly reduced in size accordingly. This increases the pressure in the collecting space 10 on until the check valve 14 in the leakage line 13 opens and the cooling medium on the leakage process 23 into the leakage line 13 and further into the cooling medium circuit 2 flows.

To a flow of cooling medium in the cooling medium circuit 2 to allow, is the check valve 14 designed such that it is above a certain opening pressure in the collecting space 10 opens. This opening pressure is greater than or equal to the sum of the back pressure in the cooling medium circuit 2 and a closing force acting as a pressure of the check valve 14 , Is by pressing the hoist 24 reached this opening pressure, then flows out of the plenum 10 displaced cooling medium over the leakage process 23 in the cooling medium circuit 2 back.

Thus, with this leakage return that in the plenum 10 Trapped cooling medium separated from in the collection chamber 10 contained air in the cooling medium circuit 2 traced. The leakage return acts like an air separator, so even with empty plenum 10 the air contained therein not in the cooling medium circuit 2 is directed.

In the 4a and 4b is a inventively designed leakage return under training of in 3 shown leakage return in an axial section through this. Again, substantially the same components are provided with the same reference numerals.

How to get out 4a can recognize the are in 3 shown components, ie essentially the throttle point 32 , The piston 24 , the check valve 14 and the collection room 10 to a structural unit, namely a leakage valve 16 summarized. The latter is present as a hollow body, comprising a valve housing 19 , educated. In the valve housing 19 lead the leakage feed 21 and the control pressure port 22 separated from each other. At one end of the hollow body is an insert 20 in the valve body 19 brought in. This has a cooling medium passage 26 in the form of a through hole, in this case the leakage process 23 forms. In this through hole is the check valve 14 arranged. Furthermore, it would be conceivable, instead of a Rückschalgventils 14 provide several such valves, which could then be connected, for example, one behind the other.

The leakage process 23 thus stands with the check valve open 14 in flow-conducting connection with the collecting space 10 , The latter is of the present cup-shaped piston 24 , in particular its insides, as well as the use 20 limited. Present is the piston 24 for its displacement in the axial direction at its collecting space 10 opposite end face with a control pressure from the control pressure port 22 acted upon. The piston 24 is here over a spring 18 , For example, a compression spring, against the use 20 biased. The spring force acts as a result of the pressurization via the control pressure connection 22 on the piston 24 counteracting acting force. She puts the piston 24 at substantially depressurized state of the control pressure port 22 in his in 4a shown position back.

As shown here, the piston forms 24 in the area of its open edge (radially outer surface) a control edge 25 out, along with the throttle 32 or the use 20 forms a valve seat. As a result, the flow cross section of the throttle point 32 depending on the position (of the stroke) of the piston 24 more or less varied. This flow cross-section thus becomes the pulse-like reduction of the volume of the collecting space 10 also abruptly diminished. Thus, an escape of the cooling medium via the throttle point 32 as the stroke of the piston progresses 24 prevented.

The piston 24 is still concentric to use 20 arranged and supported in the present case with its radially outer surface on a radially inner surface of the insert 20 from and is movable in the axial direction on the insert and / or in the valve housing 19 stored. Of course, it would be conceivable that the piston 24 with its radially inner surface on a radially outer surface of the insert 20 and / or the valve housing 19 is supported or stored differently. Also, it is not absolutely necessary that the piston has the pot-shaped shape shown.

The control pressure to pressurize the piston 24 In this case, the pressure necessary for activating the hydrodynamic retarder, for example an air pressure for actuating at least one of the switching valves 28 . 29 ( 1 ), be. Also could be the control pressure in the cooling medium circuit 22 occurring, in particular temporarily occurring relatively high pressure to be. Such a high pressure can, for example, even with activated retarder in the workspace 6 form. How to 2 B this is executed so high that the check valve 14 locks. Thus, this overpressure could be used to actuate the piston 24 to be used. In the cases illustrated, the cooling medium circuit could then be via a line 2 and in particular the work space 6 with the control pressure connection 22 be connected.

For limiting one at the control pressure connection 22 adjacent relatively high pressure could also be a throttle or a pressure reducing valve, especially in the flow direction before the control pressure port 22 be arranged.

Instead of the spring could be the piston 24 also with a negative pressure, which instead of the control pressure to the collecting space 10 turned away subspace could be applied, be brought into its reset position. There, how to the 2a and 2c executed, the pressure level in the work space 6 At times, this can be very low, this could reset the piston 24 to be used. Thus, only the permanent provision of the already mentioned line between work space 6 and control pressure port 22 suffice for the piston 24 automatically depending on the operating state of the hydrodynamic retarder 24 reset. Thus, an additional control device for actuating the leakage valve 16 unnecessary.

The displaceable amount of cooling medium through the leakage valve 16 can by the ratio of the maximum stroke or the stroke volume of the piston 24 to the flow cross section of the throttle point 32 be characterized.

4b shows in an axial section along the line BB through the leakage valve 16 out 4a the extent of the throttle point 32 , The throttle point 32 is present as a flat recess in the valve housing 19 brought in.

LIST OF REFERENCE NUMBERS

1

drive motor

2

Coolant circuit

3

hydrodynamic machine

4, 5

paddle wheel

6

working space

7

casing

8th

drive shaft

9

poetry

10

plenum

11

Coolant pump

12

surge tank

13

leakage line

14

check valve

15

float valve

16

leakage valve

17

vehicle radiator

18

feather

19

valve housing

20

commitment

21

leakage feed

22

Control pressure connection

23

leakage drain

24

piston

25

control edge

26

Coolant implementation

27

thermostatic valve

28, 29

switching valve

30

Coolant supply

31

Coolant discharge

32

restriction

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006054615 B3 [0005]

Claims (15)

Cooling system comprising 1.1 a to be cooled by means of a cooling medium drive motor ( 1 ) or another aggregate; 1.2 a cooling medium leading the cooling medium ( 2 ); 1.3 a hydrodynamic machine ( 3 ) with a first revolving impeller ( 4 ) and a second likewise revolving or stationary paddle wheel ( 5 ), which can be filled or filled with working medium ( 6 ) to generate torque hydrodynamically from the first impeller ( 4 ) on the second paddle wheel ( 5 ) transferred to; 1.4 the hydrodynamic machine ( 3 ) comprises a housing ( 7 ), which together with one of the two paddle wheels ( 4 . 5 ) the other paddle wheel ( 4 . 5 ) or the two paddle wheels ( 4 . 5 ) encloses; where 1.5 is the hydrodynamic machine ( 3 ) a drive shaft ( 8th ) to the first or second paddle wheel ( 4 . 5 ) to drive mechanically; 1.6 the drive shaft ( 8th ) is by means of a seal ( 9 ) against the housing ( 7 ) sealed; characterized by the following features: 1.7 the seal ( 9 ) includes a collection room ( 10 ) for receiving cooling medium or is connected via a working medium-conducting connection with such, in order to escape of cooling medium between the drive shaft ( 8th ) and the housing ( 7 ) to prevent; 1.8 the collection room ( 10 ) is via a leakage line ( 13 ) for returning the in the collecting space ( 10 ) with the cooling medium circuit ( 2 ) connected in a flow-conducting manner; 1.9 with one in the leakage line ( 13 ) arranged check valve ( 14 ), which the cooling medium flow in the direction of the collecting space ( 10 ) locks. Cooling system according to claim 1, characterized in that the leakage line ( 13 ) in a location of the cooling medium circuit ( 2 ), in particular within the hydrodynamic machine ( 3 ), which at times compared to the collection space ( 15 ) has a lower pressure level so that the check valve ( 14 ) opens and cooling medium from the plenum ( 10 ), and at times compared to the collecting space ( 15 ) has a higher pressure level, so that the check valve ( 14 ) closes and incoming cooling medium in the collecting space ( 10 ) accumulates. Cooling system according to claim 1 or 2, characterized in that the check valve ( 14 ) seen in the flow direction of the cooling medium, a float valve ( 15 ) and in particular in the collecting space ( 10 ) is arranged, which in dependence on the cooling medium level in the collecting space ( 10 ) the flow cross-section for cooling medium in the direction of the check valve ( 14 ) releases or locks. Cooling system according to one of claims 1 to 3, characterized in that the seal ( 9 ) additionally a cooling medium supply ( 30 ) for cooling and / or lubricating the seal ( 9 ) and a cooling medium discharge ( 31 ) for returning the cooling medium into the cooling medium circuit ( 2 ), wherein the cooling medium supply ( 30 ) and the cooling medium discharge ( 31 ) are substantially permanently flowed through. Cooling system according to one of claims 1 to 4, characterized in that the collecting space ( 10 ) an air separator is associated, which in particular in the flow direction of the cooling medium in front of the check valve ( 14 ) is arranged. Cooling system according to claim 5, characterized in that the air separator is designed as a displacement device, by means of which the cooling medium receiving volume of the collecting space ( 10 ) is impulsively reducible and the collecting space ( 10 ) seen in the flow direction of the displaced cooling medium, a throttle point ( 32 ) parallel to the leakage line ( 13 ) is connected downstream. Cooling system according to claim 6, characterized in that the displacement device comprises a displaceable piston or a deformable membrane, which / which the volume of the collecting space ( 10 ) is at least partially limited and to its displacement or deformation with a control pressure can be acted upon. Cooling system according to claim 7, characterized in that the collecting space ( 10 ), the air separator and the check valve through a leakage valve ( 16 ) are formed; the leakage valve ( 16 ) is implemented as a externally actuated valve, comprising: 8.1 a valve housing ( 19 ) in the form of a hollow body with an end-mounted insert ( 20 ), wherein in the valve housing ( 19 ) a leakage feed ( 21 ) and a control pressure port ( 22 ) and in use ( 20 ) a leakage process ( 23 ), in particular separately, open; 8.2 the leakage inflow ( 21 ) is for supplying a leakage amount of cooling medium from the gasket ( 9 ) with the collecting space ( 10 ) in a conducting connection, and the collecting space ( 10 ) is for discharging cooling medium in conductive communication with the leakage process ( 23 ); 8.3 in the leakage feed ( 21 ) is a throttle point ( 32 ) with compared to the leakage feed ( 23 ) lower flow cross-section provided; 8.4 in the valve housing ( 19 ) is a cup-shaped piston ( 24 ), which is concentric to the use ( 20 ) and together with the insert ( 20 ) the collecting space ( 10 ) limited; 8.5 the piston ( 24 ) is to its axial displacement relative to the use ( 20 ) at its the collecting space ( 10 ) facing away from the end face with a control pressure from the control pressure port ( 22 ) acted upon; 8.6 the use ( 20 ) has a cooling medium feedthrough ( 26 ), which with the collecting space ( 10 ) and the leakage process ( 23 ) is in flow-conducting connection, wherein in the cooling medium passage ( 26 ) the check valve ( 14 ) is arranged. Cooling system according to claim 8, characterized in that the piston ( 24 ) with its radially outer surface on a radially inner surface of the insert ( 20 ) is supported and stored in the axial direction movable on this; and 9.1 the piston ( 24 ) a control edge ( 25 ), which together with the insert ( 20 ) or the valve housing ( 19 ) the flow cross section of the throttle point ( 32 ) controls. Cooling system according to claim 8 or 9, characterized in that the control pressure connection ( 22 ) at a pressure supply of relatively high pressure with respect to the collecting space ( 10 ) or the leakage process ( 23 ), in particular to the cooling medium circuit ( 2 ) connected. Cooling system according to one of claims 8 to 10, characterized in that the piston ( 24 ) by means of a spring ( 18 ), in particular compression spring whose spring force against the force acting as a displacement force of the control pressure against the use ( 20 ) and / or the valve housing ( 19 ) is braced. Cooling system according to one of claims 1 to 11, characterized in that the seal ( 9 ) is a mechanical seal. Method for preventing leakage losses at a seal ( 9 ) of a hydrodynamic machine ( 3 ), the seal ( 9 ) of the hydrodynamic machine for its cooling and / or lubrication on a cooling medium circuit ( 2 ) of a cooling system, comprising the following steps: 13.1 catching one of the seals ( 9 ) leakage amount of cooling medium in a collecting space ( 10 ); 13.2 intermittent emptying of the in the collecting space ( 15 ) collected leakage amount by returning this into the cooling medium circuit ( 2 ). A method according to claim 13, characterized in that the cooling system according to any one of claims 6 to 12 is executed, comprising the following steps: 14.1 pulse-like reducing the volume of the collecting space ( 10 ) for separating the in the collecting space ( 10 ) located air of cooling medium; so that 14.2 in the collection room ( 10 ) located air through the throttle point ( 32 ) in the direction of the seal ( 9 ) is displaced; whereas 14.3 the cooling medium when a predetermined opening pressure in the collecting space ( 10 ) by opening the check valve ( 14 ) and emptying collection space ( 10 ) in the cooling medium circuit ( 2 ) is returned. A method according to claim 14, characterized in that by the pulse-like reducing the volume of the collecting space ( 10 ) also the flow cross-section of the throttle point ( 32 ) is reduced.

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