CN112997027B

CN112997027B - Working medium circuit of transmission

Info

Publication number: CN112997027B
Application number: CN201980073382.1A
Authority: CN
Inventors: A·保罗
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2018-11-09
Filing date: 2019-11-08
Publication date: 2024-05-17
Anticipated expiration: 2039-11-08
Also published as: CN112997027A; DE102018219151B4; WO2020094832A1; DE102018219151A1

Abstract

The invention relates to a working medium circuit (32) of a transmission (1) of a motor vehicle, comprising a multi-flow heat exchanger (33), wherein one region (35) of the heat exchanger (33) is designed for cooling the working medium of the transmission (1) and the other region (34) of the heat exchanger is designed for cooling the working medium of a hydrodynamic retarder (29). The working medium circuit (32) has at least one bypass (53) for bypassing a region (35) of the heat exchanger (33) for cooling the working medium of the transmission (1).

Description

Working medium circuit of transmission

Technical Field

The invention relates to a working medium circuit of a transmission of a motor vehicle. The invention also relates to a transmission comprising a working medium circuit according to the invention.

Background

In a liquid working medium in a vehicle, for example, the temperature rise due to the conversion of energy into heat is transferred to a cooling medium in a heat exchanger, in order to keep the working medium available for use and to make it available for further energy absorption.

Such working medium may be a lubricating medium in a motor or transmission that heats up due to the movement of existing components; alternatively, such a working medium may involve oil or water of a hydraulic brake device which converts the kinetic energy of the vehicle into heat by means of a blade set, which heat is transferred to the working medium.

Heat exchangers are usually implemented in the form of plate or shell structures, in which a plurality of similar plates or shells are fastened (e.g. welded) one above the other and next to the other, and then the plates or shells form passages which guide the cooling medium and the working medium to be cooled, respectively, past one another.

If a plurality of working mediums are to be cooled in the vehicle, a plurality of heat exchangers may be provided for this purpose, each of which cools the working medium by means of a cooling medium. If a plurality of heat exchangers are used for cooling a plurality of working media, the heat exchangers are optimally adapted to the working medium circuit to be cooled and have, for example, different geometries. However, the use of a plurality of heat exchangers is relatively expensive and requires correspondingly large installation or installation spaces for arranging the heat exchangers.

It is known that in vehicles, it is also possible to cool a plurality of working media in a common heat exchanger, wherein the heat exchanger then has a plurality of regions, which can each be brought into contact with a coolant for heat dissipation. Such a heat exchanger is also called a multi-flow path heat exchanger. For example, one coolant circuit and two working medium circuits may be coupled to a 3-flow heat exchanger. The working medium circuit can be designed, for example, as a working medium circuit of a transmission and as a working medium circuit of a retarder.

Such a multi-flow heat exchanger is known, for example, from DE 197 12 599a1, in which a plurality of oil supply elements are provided, which are each guided to a fixedly associated passage in order to be brought into contact there with a cooling medium which is likewise supplied to the heat exchanger for heat transfer.

Such a multi-flow heat exchanger is geometrically limited in terms of its design and can therefore be designed only conditionally for the working medium circuit to be cooled. In connection with the structural design of such a multi-flow heat exchanger, pressure losses may occur in the working medium circuit during the passage through the heat exchanger, which may have a negative effect on the working medium circuit.

Disclosure of Invention

Against this background, the object underlying the present invention is to provide an improved working medium circuit of a transmission, which has a multi-flow heat exchanger.

This object is achieved by a working medium circuit according to the invention and a transmission according to the invention.

According to the invention, a working medium circuit of a transmission of a motor vehicle is provided, which has a multi-flow heat exchanger. The heat exchanger has a plurality of areas for cooling the working medium, wherein one area of the heat exchanger is designed for cooling the working medium of the transmission and the other area of the heat exchanger is designed for cooling the working medium of the hydrodynamic retarder. According to a structural design of the heat exchanger, the heat exchanger has a corresponding flow resistance in the region of the working medium. The flow resistance of the heat exchanger in the region for cooling the working medium of the transmission can lead to a pressure increase in the working medium circuit of the transmission in certain operating regions, which can have a negative effect on the service life of the torque converter and on the shift quality of the transmission.

In order to achieve the proposed object, the present invention proposes: at least one bypass is provided in the working medium circuit for bypassing a region of the heat exchanger for cooling the working medium of the transmission. In this way, pressure increases in the working medium circuit, which can negatively affect the service life of the torque converter and the shift quality of the transmission, can be avoided.

In an advantageous development, it is provided that the throughput of the bypass is controllable or adjustable. The bypass flow can be advantageously controlled or regulated as a function of the pressure prevailing in the working medium circuit and/or the temperature of the working medium. In order to control or regulate the flow through the bypass, a valve may be arranged in the bypass.

The valve may be designed as a differential pressure valve which can be actuated as a function of the prevailing pressure before, after and in the region of the heat exchanger which is provided for cooling the working medium of the transmission, wherein the flow through the bypass is released when the pressure in the inlet line to the region of the heat exchanger which is provided for cooling the working medium reaches or exceeds a predetermined pressure value. The flow through the bypass can also be influenced by a pressure limiting valve arranged in the bypass, which opens when a predetermined pressure value is reached or exceeded in the supply line to the region of the heat exchanger which is provided for cooling the working medium. Alternatively, the valve may be designed as a proportional solenoid valve which releases the flow through the bypass depending on the current flowing through the valve coil.

The multi-flow heat exchanger is connected to the working medium circuit of the transmission in such a way that, in an operating state in which the hydrodynamic retarder is not activated, the working medium of the transmission is also guided through a region of the heat exchanger which is provided for cooling the working medium of the retarder and is cooled. The region provided for cooling the working medium of the retarder and the region provided for cooling the working medium of the transmission are then connected in series, and the working medium of the transmission is led through the two regions of the heat exchanger and cooled.

If the two areas of the heat exchanger are connected in series, the working medium of the transmission first flows through the area of the heat exchanger that is provided for cooling the working medium of the retarder and then at least partially flows through the area of the heat exchanger that is provided for cooling the working medium of the transmission that adjoins the area. In the case of a partial flow through the region of the heat exchanger provided for cooling the working medium of the transmission, the partial working medium of the transmission is guided via a bypass to bypass the region of the heat exchanger provided for cooling the working medium of the transmission, as a result of which the pressure in the supply line to the heat exchanger provided for cooling the working medium of the transmission is reduced.

The invention also relates to a transmission for a motor vehicle, comprising a multi-flow heat exchanger and a working medium circuit according to the invention.

Drawings

The invention is further elucidated hereinafter by way of example with the aid of the accompanying drawings, which allow a plurality of embodiments. In the drawings:

fig. 1 shows in schematic representation a conventional drive train of a motor vehicle, which has an automatic transmission and a torque converter,

Figure 2 shows a part of a working medium circuit according to the invention,

Fig. 3 shows an exemplary pressure curve during the operating state of the motor vehicle, and

Fig. 4 shows the arrangement of the valves in the bypass of the working medium circuit.

Detailed Description

According to fig. 1, a conventional drive train has a transmission designed as an automatic transmission 1 with a transmission housing 19, an input shaft 17 and an output shaft 18. The automatic transmission 1 has three mutually coupled planetary gear sets 2, 7, 12, which are each formed by a sun gear 3, 8, 13, a planet carrier 4, 9, 14 and a ring gear 6, 11, 16. A plurality of planet gears 5, 10, 15, which are arranged distributed on the circumferential side, are rotatably supported on the planet carriers 4, 9, 14, respectively, and mesh on the one hand with the assigned sun gears 3, 8, 13 and on the other hand with the assigned ring gears 6, 11, 16, respectively.

The output shaft 18 of the automatic transmission 1 is in driving connection with the driven device 31. For example, the output shaft 18 of the automatic transmission 1 can be in driving connection with the drive wheels of the drive axle via an axle drive (Achsgetriebe) and two drive shafts. The automatic transmission 1 has five shift elements (i.e., two plate clutches C1, C2 and three plate brakes B1, B2, B3) that act in a frictionally engaged manner for shifting six forward gears and one reverse gear.

On the input side, a torque converter 20 provided with a lockup clutch 21 is connected upstream of the automatic transmission 1. The torque converter 20 includes a pump impeller 22, a stator 23, and a turbine runner 24, which are surrounded by a casing that is not fully shown. The pump impeller 22 is rigidly connected to an input shaft 25 which is connected to a drive shaft of a drive assembly 30 and which can be connected to the input shaft 17 of the automatic transmission 1 as required via a lockup clutch 21 and a vibration damper 26. The drive assembly 30 may be designed, for example, as a combustion engine or an electric machine. The stator 23 is connected to the housing portion 28 by a one-way clutch 27, thereby preventing the stator 23 from rotating in a direction opposite to the direction of rotation of the drive motor. The turbine 24 is connected to the input shaft 17 of the automatic transmission 1. Furthermore, in order to reduce the load of the wheel brakes of the motor vehicle in question, a wear-free continuous brake is provided in the form of a hydrodynamic retarder 29 arranged on the input shaft 17 of the automatic transmission 1.

Fig. 2 depicts a part of the working medium circuit 32 of the automatic transmission 1. In order to supply the automatic transmission 1 with pressurized oil, an oil pump 42 is provided, which is advantageously arranged inside the transmission, which oil pump is coupled to the input shaft 17 of the automatic transmission 1 and can thus be driven by the drive assembly 30. Accordingly, a volumetric flow of oil in working medium circuit 32 is generated based on the rotational speed of drive assembly 30. The oil pump 42 is fed from an oil sump 43 via a suction line, wherein a suction filter 44 is connected upstream of the oil pump 42 and an oil filter 45 is connected downstream of the oil pump in order to ensure that no dirt can enter the working medium circuit 32. First, the primary pressure circuit 46 and the secondary pressure circuit 47 of the working medium circuit 32 can be supplied from the suction line.

A plurality of valves 38, 39, 40, 41 are provided in the working medium circuit 32. The valve 38 is designed as a main pressure valve which can be actuated by a pressure regulating valve, not shown here.

The torque converter relief valve 39 protects the torque converter 20 from impermissibly high overpressures in such a way that it limits the inlet pressure p0 before the torque converter 20. The inlet pressure p0 upstream of the torque converter 20 is set by the torque converter relief valve 39, wherein when a certain pressure value is reached or exceeded the torque converter relief valve 39 opens, so that the oil can flow out by way of the return flow in the direction of the suction side of the oil pump 42, more precisely into the oil sump 43, until the desired inlet pressure p0 is again reached.

After the torque converter 20, a torque converter back pressure valve 40 is arranged in the torque converter exhaust line, by means of which the pressure p1 after the torque converter 20 is set. If the pressure p1 downstream of the torque converter 20 exceeds a predetermined pressure value, the torque converter back pressure valve 40 opens, so that the working medium of the automatic transmission 1 can flow out in the direction toward the cooling circuit or the lubrication circuit until the pressure p1 downstream of the torque converter 20 is again generated.

A heat exchanger 33 is arranged in the working medium circuit 32, which heat exchanger comprises two areas 34, 35 for cooling the working medium. The first zone 34 is used for cooling the oil as working medium of the hydrodynamic retarder 29. The second region 35 serves to cool oil as a working medium of the automatic transmission 1. In addition to the retarder oil circuit and the transmission oil circuit, a coolant circuit 37, for example a coolant circuit 37 of a motor vehicle, which includes a vehicle heat exchanger 36, is connected to the heat exchanger 33. The heat exchanger 33 is therefore designed here as a so-called 3-flow heat exchanger.

The valve 41 is controlled according to retarder operation. As illustrated in fig. 2, the retarder 29 is not activated in the first operating state and the remaining working medium remaining in the retarder 29 is led out through the valve 41 via the line 48 into the oil sump 43. The supply of working medium into the retarder 29 via line 49 is prevented by valve 41. The first operating state is, for example, a traction operation of the motor vehicle. During the first operating state, the working medium of the automatic transmission 1 to be cooled is guided both through the first region 34 of the heat exchanger 33 and through the second region 35 of the heat exchanger and is thus cooled by the two regions 34, 35 of the heat exchanger 33.

In a second operating state, in which the retarder 29 is activated manually or by means of a control mechanism, the working medium is fed via the line 50 into the working chamber of the retarder 29. The valve 41 is then adjusted to its second position. The working medium warmed up in the retarder 29 can thereby be transferred via the line 48 into the line 51 and then cooled by the first region 34 of the heat exchanger 33. The now cooled working medium from the region 34 of the heat exchanger 33 is supplied to the retarder 29 for further use via the valve 41 and the line 49. The working medium of the automatic transmission 1 to be cooled during operation of the retarder is supplied via the valve 41 and the line 52 to the second region 35 of the heat exchanger 33 and cooled via this second region. In the second operating state, the working medium of the retarder 29 and the working medium of the automatic transmission 1 are therefore cooled in two mutually separate cooling medium circuits. The second operating state is, for example, a coasting operation of the motor vehicle.

In the case of a 3-channel heat exchanger 33, in which a first region 34 and a second region 35 are produced in the component, the structure of these two regions 34, 35 is restricted by corresponding regulations. The 3-channel heat exchanger 33 can thus be produced, for example, in a plate-type structure, wherein the dimensions and number of plates used for the two regions 34, 35 cannot be selected arbitrarily. According to the structural design of the heat exchanger 33, the heat exchanger 33 has a corresponding flow resistance. The flow resistance results in a corresponding pressure loss of the heat exchanger 33, which may have a negative effect on the working medium circuit 32. It is thus possible, for example, to disable the function of the torque converter back pressure valve 40, so that the torque converter internal pressure and thus also the pressure p1 downstream of the torque converter 20 is no longer determined by the torque converter back pressure valve 40 but rather by a loss of the downstream working medium circuit and thus rises. This pressure increase negatively affects the service life of the torque converter 20 and the shift quality of the automatic transmission 1 and also results in an earlier switching (Umschalten) of the torque converter safety valve 39, as a result of which the amount of working medium required for cooling or lubricating the torque converter 20 and for the automatic transmission 1 is led out into the oil sump 43 and is no longer available for cooling or lubricating the automatic transmission 1 and for the torque converter 20.

Thus, according to the invention, at least one bypass 53 is provided in the working medium circuit 32 for bypassing the region 35 of the heat exchanger 33 for cooling the working medium of the automatic transmission 1, via which bypass part of the working medium of the automatic transmission 1 can be guided past the second region 35 of the heat exchanger 33.

Since the second region 35 of the heat exchanger 33 is flown through by the working medium of the automatic transmission 1 in both the traction operation and the coasting operation of the motor vehicle, the torque converter internal pressure or the pressure p1 after the torque converter 20 in the working medium circuit 32 in both the traction operation and the coasting operation is restricted, and the above-described drawbacks can be avoided.

A valve 54, which is designed here as a differential pressure valve, is arranged in the bypass 53. Starting from the predetermined pressure p2, the valve 54 opens and leads a partial volume flow of the working medium of the automatic transmission 1 past the second region 35 of the heat exchanger 33. As a result, the pressure p2 upstream of the second region 35 of the heat exchanger 33 decreases, as a result of which an increase in the internal torque converter pressure and thus an earlier switching of the torque converter relief valve 39 is avoided. Thus, the functions of the torque converter backpressure valve 40 and the torque converter relief valve 39 are not negatively affected.

The viscosity of the working medium of the automatic transmission 1 varies according to the temperature of the working medium. In the case where the automatic transmission 1 is cold, for example, in the case where the working medium temperature is lower than 50 ℃, the pressure loss in the working medium circuit 32 of the automatic transmission 1 is larger due to the greater flow resistance than in the case where the working medium temperature is high. In order to prevent a temperature-dependent increase in the pressure p1 in the torque converter outlet line in the case of a cold automatic transmission 1, a further bypass (not shown here) can be provided, which serves to bypass the second region 35 of the heat exchanger 33 and via which a part of the working medium of the automatic transmission 1 is guided past the second region 35 of the heat exchanger 33 in the case of a cold automatic transmission 1. For this purpose, the working medium volume flow flowing through the further bypass is set, for example, by a bimetallic valve or a wax motor. By flowing at a lower temperature around the region 35 of the heat exchanger 33 for cooling the working medium of the automatic transmission 1, the pressure loss at the region 35 of the heat exchanger 33 is reduced, so that an increase in the pressure p2 at the region 35 entering the heat exchanger 33 and thus also an increase in the pressure p1 in the torque converter exhaust line and also an increase in the torque converter internal pressure can be avoided. In the event of a predefinable working medium temperature being reached, this flow through the second region 35 of the second bypass heat exchanger 33 is prevented by the bimetallic valve or the wax motor.

Fig. 3 shows, by way of example, a pressure curve during a traction operation of a motor vehicle. The working medium to be cooled of the automatic transmission 1 is guided here both through the first region 34 of the heat exchanger 33 and through the second region 35 of the heat exchanger and is thus cooled by the two regions 34, 35 of the heat exchanger 33. The pressure p1 prevailing after the torque converter 20 is shown in relation to the rotational speed of the drive assembly 30 of the motor vehicle.

The characteristic line 55 shown in dashed lines shows the curve of the pressure p1 in the torque converter outlet line in the working medium circuit without the bypass 53 according to the invention, while the characteristic line 66 shows the curve of the pressure p1 in the torque converter outlet line in the working medium circuit 32 comprising the bypass 53 according to the invention. As is evident from an examination of the characteristic line 55 shown, the pressure p1 in the torque converter outlet line rises at a rotational speed of the drive train of the motor vehicle in the range of 1400 revolutions per minute. This is based on: at this point the torque converter back pressure valve 40 has fully opened and the pressure p2 before the second region 35 of the heat exchanger 33 has increased further due to the flow resistance of the heat exchanger. The pressure p1 in the torque converter outlet line and thus also the internal torque converter pressure of the torque converter 20 is then determined by the pressure p2 prevailing in the working medium circuit 32 and likewise increases, which negatively affects the service life of the torque converter 20 and the shift quality of the automatic transmission 1.

In order to avoid a pressure increase, a bypass 53 is provided in the working medium circuit 32 according to the invention, via which bypass part of the working medium of the automatic transmission 1 is guided to pass by the second region 35 of the heat exchanger 33 if the pressure p2 in the inlet line 52 to the second region 35 of the heat exchanger 33 reaches or exceeds a predetermined pressure value. This prevents the pressure p2 from rising due to the flow resistance of the second region 35 of the heat exchanger 33 and thus also prevents the pressure p1 in the torque converter outlet line and the internal pressure of the torque converter from rising. This is shown by the feature line 66 shown in fig. 3.

If the motor vehicle is operated in coasting mode by means of the activated retarder 29, the working medium to be cooled of the automatic transmission 1 is guided only through the second region 35 of the heat exchanger 33, as a result of which a lower flow resistance in the working medium circuit 32 is dominant for the working medium of the automatic transmission 1. This results in a lower pressure p2 being generated before the second region 35 of the heat exchanger 33 during coasting operation with the same rotational speed of the drive assembly 30. Accordingly, such a pressure level is only reached at high rotational speeds, for example at a rotational speed of the drive assembly 30 of approximately 1800 revolutions per minute, from which the working medium of the automatic transmission 1 is guided via the bypass 53 past the second region 35 of the heat exchanger 33. The pressure p2 can be reliably prevented from rising due to the flow resistance of the second region 35 of the heat exchanger 33 even during coasting operation, and therefore the pressure p1 in the torque converter outlet line and the torque converter internal pressure can also be prevented from rising.

Fig. 4 shows the arrangement of a valve 54 in a bypass 53 of the working medium circuit 32. The valve 54 is arranged in an oil supply flange 57, which is embodied as a channel plate. The oil supply flange 57 has corresponding channels and forms, together with the intermediate plate 60, corresponding oil channels 61 of the working medium circuit 32, which intermediate plate has a plurality of passages and is arranged between the oil supply flange 57 and a valve housing of the working medium circuit 32, which is not shown here.

The piston face 62 of the valve piston 58 of the valve 54 is formed directly in the oil supply flange 57. The valve piston 58 is pressed against the intermediate plate 60 by means of the spring force of a spring 59 arranged in the valve piston 58 and the force acting on the valve piston 58 due to the pressure p3 acting on the piston face of the valve piston 58, whereby the valve piston 58 abuts against the intermediate plate 60. Through at least one through-opening 56 provided in the valve piston 58 (which can be realized, for example, by means of a bore), the working medium can be guided into the region of the valve piston 58 in which the spring 59 is arranged. The piston surface on which the pressure p3 can act and thus the force acting on the valve piston 58 by the pressure p3 correspondingly increases. The valve piston 58 of the valve 54 is applied with a pressure p2 via a through-hole 63 in the intermediate plate 60. The through-holes 63 in the intermediate plate 60 can be embodied, for example, as holes or can be produced by punching.

The valve 54 is designed here as a differential pressure valve. The valve piston 58 of the valve 54 is actuated in dependence on the pressure difference between the pressure p2 in the inlet line 52 to the second region 35 of the heat exchanger 33 and the pressure p3 after the second region 35 of the heat exchanger 33. If the pressure p2 in the supply line 52 rises to a predetermined pressure level, the valve piston 58 is displaced to the left in the drawing plane and the valve 54 is opened. With the valve 54 open, part of the working medium of the automatic transmission 1 is guided past the second region 35 of the heat exchanger 33, so that an increase in the pressure p2 in the supply line 52 to the second region 35 of the heat exchanger 33 is avoided.

By the aforementioned arrangement and design of the valve 54, it is possible to integrate the valve in the oil supply flange 57 particularly simply, space-saving and cost-effectively without additional piping or the like for operating the valve 54.

List of reference numerals

1 Automatic Transmission

2 First planetary gear set

3 Sun gear

4 Planetary carrier

5 Planetary gear

6-Ring gear

7 Second planetary gear set

8 Sun gear

9 Planet carrier

10 Planetary gear

11-Ring gear

12 Third planetary gear set

13 Sun gear

14 Planet carrier

15 Planetary gear

16-Ring gear

17 Input shaft

18 Output shaft

19 Shell body

20 Torque converter

21 Lock-up clutch

22 Pump wheel

23 Guide pulley

24 Turbine

25 Input shaft

26 Vibration damper

27 One-way clutch

28 Housing part

29 Main retarder

30 Drive assembly

31 Driven device

32 Working medium circuit

33 Heat exchanger

34 Region

Region 35

36 Heat exchanger

37 Cooling medium loop

38 Valve

39 Valve

40 Valve

41 Valve

42 Oil pump

43 Oil pan

44 Suction filter

45 Oil filter

46 Main pressure circuit

47 Times pressure loop

48 Pipeline

49 Pipeline

50 Pipeline

51 Pipeline

52 Pipeline

53 Bypass

54 Valve

55 Pressure curve

56 Through part

57 Oil supply flange

58 Valve piston

59 Spring

60 Intermediate plate

61 Oil passages

62 Piston face

63 Through part

66 Pressure curve

B1 gear shifting element and sheet brake

B2 gear shifting element and sheet brake

B3 shift element, sheet brake

C1 gear shifting element, plate clutch

C2 shift element, plate clutch

Claims

1. A working medium circuit (32) of a transmission (1) of a motor vehicle, which has a multi-flow heat exchanger (33), wherein one region (35) of the heat exchanger (33) is designed for cooling the working medium of the transmission (1) and the other region (34) of the heat exchanger (33) is designed for cooling the working medium of a hydrodynamic retarder (29), characterized in that the working medium circuit (32) has at least one bypass (53) for bypassing the region (35) of the heat exchanger (33) for cooling the working medium of the transmission (1), wherein, in the case of an unactuated transmission (29), the working medium of the transmission (1) is also guided through the region (34) of the heat exchanger (33) which is provided for cooling the working medium of the retarder (29) and is cooled, and wherein the working medium of the transmission (1) flows completely through the region (33) which is provided for cooling the working medium of the heat exchanger (29), the region (35) which is provided for cooling the working medium of the transmission (1), wherein the working medium of the transmission (1) flows through the bypass (53) from the side of the region (35) of the heat exchanger (33) which is provided for cooling the working medium of the transmission (1) while partially flowing through the region (35) of the heat exchanger (33) which is provided for cooling the working medium of the transmission (1).

2. The working medium circuit (32) according to claim 1, wherein the flow rate of the bypass (53) is controllable or adjustable.

3. Working medium circuit (32) according to claim 2, characterized in that a valve (54) is arranged in the bypass (53) in order to control or regulate the flow through the bypass (53).

4. A working medium circuit (32) according to claim 3, characterized in that the valve (54) is designed as a differential pressure valve, which is actuatable as a function of the pressure (p 2) before the first region (35) of the heat exchanger (33) which is arranged for cooling the working medium of the transmission (1) and the pressure (p 3) after the first region.

5. The working medium circuit (32) according to claim 3 or 4, characterized in that the valve (54) is arranged in an oil supply flange (57) of the transmission (1).

6. The working medium circuit (32) according to claim 5, characterized in that the oil supply flange (57) forms a piston working surface (62) for a valve piston (58) of the valve (54).

7. A working medium circuit (32) according to claim 3, characterized in that the valve (54) is designed as a pressure limiting valve or a proportional solenoid valve.

8. Transmission (1) of a motor vehicle, comprising a multi-flow heat exchanger (33) and a working medium circuit (32) according to any one of claims 1 to 7.