Shaft for motor

Abstract

A shaft (12) for an electric motor (10), comprising: an outer shaft part (32) connected to a rotor (14) of the electric motor in a rotationally fixed manner; an inner shaft part (30) connected to the outer shaft part in a rotationally fixed manner and serving as an output shaft of the electric motor; an inflow part (36) arranged between the outer shaft part and the inner shaft part in a radial direction for supplying a cooling fluid (28) to the shaft; and an outflow part (42) arranged between the outer shaft part and the inner shaft part in a radial direction for conducting the cooling fluid supplied to the shaft, wherein the outer shaft part surrounds a fluid chamber (40) arranged between the inflow part and the outflow part in an axial direction; the fluid chamber is used to accommodate the cooling fluid in order to cool the shaft; and the flow direction of the cooling fluid in the fluid chamber is determined by the delivery direction of the fluid pump (24). The invention also relates to an electric motor (10) having such a shaft and a system (20) for cooling such an electric motor.

Description

Technical Field

[0001] The invention relates to a shaft for an electric machine, an electric machine and a system for cooling an electric machine. Background Art

[0002] Vehicles are increasingly equipped with hybrid drives or pure electric drives. Hybrid drives can help reduce fuel consumption and harmful emissions. To a large extent, drive trains with internal combustion engines and one or more electric motors are implemented as parallel hybrids or hybrid hybrids. Since the drive torques of the electric drive and the internal combustion engine can be added depending on the control situation, a relatively small design of the internal combustion engine and / or its temporary shutdown can be achieved. This can significantly reduce CO2 emissions without significant power losses or comfort losses. Pure electric vehicles can sometimes be operated without significant emissions.

[0003] In particular when using electric motors which can reach very high rotational speeds, for example in the range of 20,000 revolutions per minute, the components of the electric motor are subjected to great loads and high temperatures. It is therefore known to limit the energy input to the electric motor in order to prevent excessive heating of the electric motor and the resulting damage to the electric motor. However, the electric motor is thus not able to fully utilize its full potential.

[0004] It is also known to cool the electric machine by means of cooling ribs arranged on its housing or a water cooler arranged on the housing. Such cooling is only inefficient because the cooling takes place at a large distance from the heat source.

[0005] A motor with a hollow shaft is known from document WO 2018 / 050380 A1, and the hollow shaft is supported in a bearing so that the hollow shaft can rotate around the axis of rotation. When the motor is running, the hollow shaft is flowed through by a cooling medium. The hollow shaft is axially and / or radially adjacent to a clutch component in an external medium-tight manner at an axial end, and the cooling medium is supplied to and / or sent out of the hollow shaft by the clutch component. The bearing element is arranged on the clutch component in a non-rotatable manner and centered relative to the axis of rotation, and the bearing element extends into the hollow shaft and is surrounded by the cooling medium. On the bearing element, the sensor element is arranged centered relative to the axis of rotation. At the inner side of the hollow shaft, the dimension gauge is connected to the hollow shaft in a non-rotatable manner. The dimension gauge and the sensor element act together, so that the rotational position of the hollow shaft and / or the change of the rotational position of the hollow shaft can be determined according to the signal sent by the sensor element. Disadvantageously, the hollow shaft is used as the output shaft of the motor. Therefore, the hollow shaft must have a correspondingly large wall thickness, which makes the cooling of the motor by the hollow shaft inefficient. In addition, the connection of the hollow shaft to the mechanism and the organization of the fluid circulation are associated with high technical costs.

[0006] It is generally desirable to cool the electric machine as effectively as possible in order to keep the restriction of the energy supplied to the electric machine as small as possible. Limiting the energy supplied is accompanied by a loss of efficiency of the electric machine. In particular, different operating modes are provided in electric machines for motor vehicles. For example, the electric machine can be operated in a regeneration mode. In this mode, the low efficiency of the electric machine leads to losses in energy recovery. As a result, a portion of the almost freely available energy cannot be recovered and used. It is therefore of particular interest to increase the efficiency of electric machines, in particular electric machines for motor vehicles. Summary of the invention

[0007] Against this background, the object of the present invention is to provide a possibility for improving the cooling of an electric machine, in particular to provide a device which enables cooling at a short distance from the heat source.

[0008] In order to achieve this object, the present invention relates to a shaft for cooling an electric machine, the shaft having:

[0009] An outer shaft component, the outer shaft component is connected to the rotor of the motor in a non-rotatable manner relative to each other;

[0010] An inner shaft component, which is connected to the outer shaft component in a non-rotatable manner and is an output shaft of the motor;

[0011] an inflow portion arranged in a radial direction between the outer shaft component and the inner shaft component for supplying a cooling fluid to the shaft; and

[0012] an outflow arranged in radial direction between the outer shaft part and the inner shaft part for discharging cooling fluid supplied to the shaft, wherein

[0013] The outer shaft member surrounds a fluid chamber, and the fluid chamber is arranged between the inflow portion and the outflow portion in the axial direction;

[0014] The fluid cavity is used to contain the cooling fluid so as to cool the shaft; and

[0015] The flow direction of the cooling fluid in the fluid chamber is determined by the delivery direction of the fluid pump.

[0016] The present invention also relates to an electric motor, comprising:

[0017] stator;

[0018] rotor; and

[0019] A shaft as described above, wherein the shaft is connected to the rotor of the electric machine in a rotationally fixed manner.

[0020] Furthermore, the invention relates to a system for cooling an electric machine, preferably a predefined electric machine, comprising:

[0021] a fluid sump for storing cooling fluid; and

[0022] A fluid pump is used to deliver the cooling fluid from the fluid sump to the motor so as to form a cooling circuit.

[0023] The preferred design of the present invention is described below. It is understood that the above-mentioned features and the features to be explained below can be used not only in the respectively indicated combination, but also in other combinations or alone without departing from the scope of the present invention. It is also understood that the features and advantages mentioned here can be applied to each motor independently of its intended use.

[0024] By providing a shaft for the motor, which has an outer shaft component and an inner shaft component, wherein the outer shaft component surrounds a fluid chamber, a fluid chamber for cooling the motor can be provided inside the motor. Heat can be directly conducted out of the inside of the motor. The cooling of the motor can be achieved technically simply and effectively. By providing the inner shaft component as the output shaft of the motor, other components can be omitted. The motor can be manufactured technically simply with fewer components. A cooling circuit can be formed by presetting or determining the flow direction of the cooling fluid in the fluid chamber by the delivery direction of the fluid pump. When the motor is running, the cooling fluid in the fluid chamber radially presses the inner wall of the outer shaft component outward due to centrifugal force, thereby covering a larger surface area inside the fluid chamber with the cooling fluid. At this time, the cooling is further improved.

[0025] In a preferred embodiment, the outer shaft part has a connecting section, which connects the outer shaft part to the inner shaft part in a non-rotatable manner. The inlet has a channel, a punching and / or a bore in the connecting section. By means of the inlet in the form of a channel, a punching and a bore in the connecting section, the inlet can be converted technically simply. No further components are required to supply the shaft with cooling fluid. By providing a connecting section that connects the outer part of the shaft to the inner shaft part in a non-rotatable manner, the shaft can be constructed with fewer components.

[0026] In an advantageous embodiment, the connecting section has a driving toothing in order to connect the inner shaft part and the outer shaft part to each other in a rotationally fixed manner. This makes it possible to realize a rotationally fixed connection between the inner shaft part and the outer shaft part in a cost-effective manner. In addition, the manufacture of the shaft is simplified, since the inner shaft part can be simply inserted or pressed into the outer shaft part in order to form the shaft.

[0027] In an advantageous embodiment, the outflow is formed by a gap between the outer shaft part and the inner shaft part. This allows the hot cooling fluid to flow out of the fluid chamber in a technically simple manner. It is also preferred that there is no fixed connection between the inner shaft part and the outer shaft part in the region of the outflow, so that the inner shaft part can be retracted better in order to compensate for play, for example, in a device connected to the shaft.

[0028] In a preferred embodiment, the inner shaft part has a support web in the region of the outflow for supporting the inner shaft part on the outer shaft part. This makes it possible to form a substantially rigid shaft. In particular, it is technically simple to support the inner shaft part and simultaneously allow the heated cooling fluid to flow out.

[0029] In a preferred embodiment, the outflow opens into a supply line to the fluid sump. In this way, a cooling circuit can be formed in a technically simple manner. In addition, the heated and moving fluid is deposited in the fluid sump. Possible bubbles in the cooling fluid can migrate upwards due to their lower density. When the cooling fluid is sucked out of the fluid sump again by means of a fluid pump and recooled, lower stirring losses and higher cooling performance can be achieved.

[0030] In another advantageous embodiment, the end section of the inner shaft part projects further in the axial direction than the outer shaft part in order to form an output shaft of the electric machine. In this way, cooling and connection to the mechanism can be realized in a technically simple manner with only one component. This shaft is used instead of the output shaft for electric machines known in the prior art.

[0031] In an advantageous embodiment, the end section is connected to the mechanism and / or forms a part of the mechanism itself. In this way, the shaft can be effectively connected to the mechanism without the effect of other auxiliary parts.

[0032] In an advantageous embodiment, the outer shaft part is made of two parts. The two parts are connected in a fluid-tight manner by means of compression joining, friction welding and / or adhesive bonding. In this way, the production of the outer shaft part can be achieved in a technically simple manner. In addition, it can be ensured that the fluid cannot pass through the connection between the two parts into the rotor of the electric machine.

[0033] In an advantageous embodiment of the electric machine, the electric machine has a sensor wheel. The sensor wheel rotates together with the shaft and comprises a hole so that cooling fluid can be supplied to the shaft through the sensor wheel. In this way, the speed and direction of rotation of the electric machine can be monitored in a technically simple and reliable manner, wherein the supply of cooling fluid to the shaft of the electric machine is ensured.

[0034] In another advantageous embodiment of the electric motor, the outer shaft part is connected to the rotor of the electric motor in a rotationally fixed manner by means of a press fit. In this way, a rotationally fixed connection of the shaft to the rotor of the electric motor can be realized cost-effectively.

[0035] In another advantageous embodiment of the electric machine, the electric machine is operatively connected to a transmission on a shaft. The outflow delivers cooling fluid to the transmission in order to lubricate and / or cool the transmission. In this way, the operatively connected transmission can be cooled and lubricated in a technically simple manner. Preferably, additional lubrication and cooling of the transmission can be omitted.

[0036] In an advantageous embodiment, the system for cooling the electric machine has a heat exchanger in order to extract heat from the cooling fluid. The heat exchanger is preferably arranged between the fluid sump and the fluid pump in the direction of the fluid flow. In this way, the cooling of the electric machine can be further improved. Additional heat can be extracted from the cooling fluid.

[0037] Depending on the place of use and the area of ​​use, the cooling fluid has many different compositions. Thus, for example, mineral oil and / or synthetic oil with or without additives can be used. It is also conceivable to use water with or without additives, in particular deionized water. Alcohols or ethers can also be used as cooling fluids with or without additives. In principle, depending on the purpose of use, any gas or any liquid can be used as cooling fluid. Currently, liquid or flowable substances can be used as cooling fluids over the entire temperature range.

[0038] Regeneration is the recovery of energy during braking. Regenerative brakes, also called feedback brakes, work like every electric dynamic brake without wear. The braking effect is achieved by operating the traction motor as a generator. The electrical energy can be stored in the vehicle, for example, in a battery or supercapacitor.

[0039] A sensor wheel is a device for generating a signal that is correlated with the angular position or rotational position of the sensor wheel. For example, an angle signal or a rotational speed signal can be generated by means of periodic gaps in the toothed ring or by means of an inductive sensor based on a change in a magnetic field. A uniform tooth structure corresponds to a sinusoidal voltage profile. Furthermore, by using gaps of different sizes at defined distances, a defined gear position can be transmitted to the control device, resulting in a change in the voltage profile. It is also conceivable to determine the angular position or the rotational speed optically, for example by passing the teeth of a gear through a light barrier.

[0040] Agitation losses are efficiency losses. They lead to an impairment of the cooling properties of the cooling fluid, which is caused by contamination, preferably by gas bubbles. The impurities usually have worse thermal properties than the cooling fluid, so that the contaminated cooling fluid can absorb less heat. In addition, if the cooling fluid is contaminated by air inclusions, the viscosity of the cooling fluid can change, so that the fluid pump works inefficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be described and explained in more detail below with the help of several selected embodiments in conjunction with the accompanying drawings. The accompanying drawings show:

[0042] Figure 1 is a schematic diagram of an electric machine having a shaft according to the present invention;

[0043] Figure 2 is a schematic diagram of a cooling system according to the present invention;

[0044] Figure 3 is a schematic detail view of a shaft of a motor;

[0045] Figure 4 is a technical diagram of an electric machine having a shaft; and

[0046] Figure 5 is another technical diagram of an electric machine having a shaft. DETAILED DESCRIPTION

[0047] exist Figure 1 Schematically shows an electric motor 10. The electric motor 10 has a shaft 12, which is non-rotatably connected to a rotor 14 of the electric motor. A stator 16 of the electric motor 10 is non-rotatably connected to a housing 18. It is understood that the stator 16 can also be operatively connected to another component that prevents a rotational movement of the stator 16 relative to the rotor 14. The illustration is to be understood as exemplary and does not show the correct proportions of the components. In addition, the illustration of other details is omitted.

[0048] During operation of the electric motor 10, the rotor 14 and the shaft 12 rotate at the same rotational speed. The stator 16 is connected to the housing 18 so that the stator does not substantially move, in particular does not rotate. The electric motor 10 may be a DC motor, an AC motor, or a three-phase AC motor. In general, the present invention may be used with any electric motor having an output shaft.

[0049] exist Figure 2 Schematically shown in FIG. 2 is a system 20 for cooling an electric machine 10 . The system 20 includes a fluid sump 22 , a fluid pump 24 and a pipeline 26 .

[0050] The fluid pump 24 delivers the cooling fluid 28 from the fluid sump to the shaft 12 of the motor 10. The cooling fluid 28 absorbs heat from the motor 10. The cooling fluid 28 in the shaft 12 is forced out of the shaft 12 of the motor 10 by further delivering the cooling fluid 28 and flows back into the fluid sump 22 again.

[0051] Here, the fluid pump 24 can be any type of pump suitable for conveying the cooling fluid. It is understood that one or more heat exchangers can be provided in the system 20 in order to better cool the cooling fluid 28. In addition, a fluid filter can be provided in order to filter out suspended matter from the cooling fluid 28. In addition, one or more temperature sensors can be provided in order to obtain the temperature of the motor 10 and / or the cooling fluid 28. It is conceivable that the fluid pump 24 is adjusted according to the temperature of the motor 10 and / or the cooling fluid 28. This diagram can be understood as a minimal diagram that satisfies the function. It is also conceivable that the fluid pump 24 operates another cooling circuit.

[0052] exist Figure 3 Schematically shows a detailed view of the shaft 12 of the electric machine 10. The shaft 12 has a first inner shaft part 30 arranged radially inside, which is a solid shaft in the illustrated embodiment. In addition, the shaft 12 has a second outer shaft part 32 arranged radially outside, which is a hollow shaft and surrounds the inner shaft part 30.

[0053] A sensor wheel 34 is arranged on the shaft in order to obtain the rotational speed of the shaft 12 and thus the rotor 14 of the motor 10. The sensor wheel 34 has a recess so that the fluid is delivered to the fluid chamber 40 through the inlet 36 in the form of a channel located in the connecting section 38 via the sensor wheel 34. The outflow 42 is configured in the form of a gap between the inner shaft part 30 and the outer shaft part 32. Depending on the application, a supporting web 41 can also be provided in the area of ​​the outflow 42 in order to support the outer shaft part 32 on the inner shaft part 30. The connecting section 38 connects the inner shaft part 30 and the outer shaft part 32 to each other in a non-rotatable manner. For this purpose, the connecting section 38 can have a driving toothing. It is also conceivable that the two shaft parts 30, 32 are welded or bonded to each other. It is also conceivable to press the joint.

[0054] Figure 4 The technical diagram schematically shows a detail of a section of an electric machine 10 with a shaft 12. The same reference numerals refer to the same features and are not explained again. The figure is a sectional view.

[0055] In the embodiment shown, the shaft 12 has a mechanism in the form of a transmission 44 on its outflow side. The radially outer shaft part is formed by a first part 32a and a second part 32b. In addition, the shaft 12 has a driving toothing 46 on its connecting section 38 in order to connect the outer shaft part 32 to the inner shaft part 30 in a rotationally fixed manner. The two parts 32a, 32b are connected to each other in a fluid-tight manner by means of friction welding.

[0056] If the electric machine 10 and in particular the shaft 12 are connected to a fluid circuit, the cooling fluid 28 is sucked out of the fluid sump 22 by the fluid pump 24. The fluid pump 24 introduces the cooling fluid 28 through the line 26 and the hydraulic screw connection into the shaft 12. A seal, such as a radial shaft seal or a combination of a sealing ring and a baffle, is present between the sensor wheel 34, which rotates with the inner shaft part 30 and the outer shaft part 32 of the electric machine 10 and the rotor 14, and the bearing cover 48.

[0057] Cooling fluid 28 flows through holes in bearing cover 48 into the interior of sensor wheel 34, that is, into the recess of the sensor wheel. From there, the cooling fluid is introduced into shaft 12 via a plurality of inflows 36 in the form of holes in sensor wheel 34 and is received in fluid chamber 40.

[0058] In order that the cooling fluid 28 does not continue to flow through the gap between the inner shaft part 30 and the outer shaft part 32, the gap is sealed by a seal 50, wherein the seal 50 arranged on the connecting section 38 is also sealed relative to the grease-lubricated bearing or space of the electric machine. Preferably, the seal 50 is an O-ring, wherein the O-ring usually seals components with the same rotation speed or rigid components relative to each other. Conversely, the seal 54 can be, for example, a radial shaft sealing ring or a combination of a sealing ring and a baffle, wherein the seal 54 seals components with different rotation speeds relative to each other. As a result, the cooling fluid 28 flows into the fluid chamber 40 and preferably flows to the vicinity of the outer shaft part 32. As a result, the cooling fluid 28 reaches the vicinity of the rotor 14 of the electric machine 10. Good cooling performance is achieved. The cooling performance is assisted by the centrifugal force (rotation of the shaft 12), wherein the cooling fluid 28 in the fluid chamber 40 is guided to the wall of the outer shaft part 32 and absorbs heat from the rotor 14 of the electric machine 10. The outer shaft part 32 is composed of two parts, wherein the two parts 32a and 32b are connected to each other in a fluid-tight manner. This can be achieved, for example, by friction welding or compression joining.

[0059] The fluid chamber 40 of the shaft 12 can already be forged into the shaft 12, but can also be machined out by cutting. The outer shaft part 32, on which the rotor 14 of the electric machine 10 is mounted, preferably has a larger contact surface than the rotor 14 of the electric machine 10, in order to achieve an increased heat transfer capacity from the electric machine 10 to the outer shaft part 32, wherein the heat is ultimately dissipated to the cooling fluid 28. Since the fluid chamber 40 of the shaft 12 is closed, the cooling fluid 28 flows into the outflow 42 in the form of a gap between the inner shaft part 30 and the outer shaft part 32 and returns from there to the fluid sump 22.

[0060] Figure 5 A technical diagram of an electric machine 10 with a shaft 12 according to the invention is shown. The same reference numerals relate to the same features and are therefore not explained again.

[0061] Figure 5 A cross-sectional view is shown, wherein the shaft 12 of the motor 10 and thus the rotor 14 of the motor are connected to the Figure 4 . In this section, inlet 36 is not visible. Furthermore, other details in bearing cap 48 and gear mechanism 44 are not shown. In sensor wheel 34, holes 52 are shown, which allow cooling fluid 28 to flow through sensor wheel 34 into inlet 36 in connecting section 28, which is not visible in this rotational position of rotor 14, shaft 12 and sensor wheel 34.

[0062] The present invention has been fully described and explained with the aid of the drawings and the specification. The description and explanation should be regarded as illustrative rather than restrictive. The present invention is not limited to the disclosed embodiments. Other embodiments or variations will be apparent to those skilled in the art when using the present invention and when analyzing the drawings, the disclosure and the following claims in detail.

[0063] In the claims, the words "comprising" and "having" do not exclude the presence of other elements or steps. The indefinite article "a" or "an" does not exclude the presence of a plurality. The mere mention of some measures in several different dependent claims should not be interpreted as meaning that a combination of these measures cannot be used to the same advantage. Reference signs in the claims should not be understood as limiting.

[0064] List of reference numerals:

[0065] 10 Motor

[0066] 12 Axis

[0067] 14 Rotor

[0068] 16 Stator

[0069] 18 Housing

[0070] 20 Systems

[0071] 22 Fluid sump

[0072] 24 Fluid Pump

[0073] 26 Pipeline

[0074] 28 Cooling fluid

[0075] 30 Inner shaft components

[0076] 32 External shaft components

[0077] 34 Sensor wheel

[0078] 36 Inflow

[0079] 38 Connection section

[0080] 40 Fluid chamber

[0081] 41 Support tab

[0082] 42 Outflow part

[0083] 44 Transmission mechanism

[0084] 46 Drive gear

[0085] 48 Support cover

[0086] 50 Sealing part

[0087] 52 Hole in sensor wheel

[0088] 54 Sealing part.

Claims

1. A shaft (12) for an electric motor (10), comprising: An outer shaft component (32) connected to the rotor (14) of the motor in a non-rotatable manner relative to the outer shaft component; An inner shaft component (30), which is connected to the outer shaft component in a non-rotatable manner and is an output shaft of the motor; an inflow portion (36) arranged in a radial direction between the outer shaft component and the inner shaft component for supplying a cooling fluid (28) to the shaft; as well as an outflow (42) arranged in the radial direction between the outer shaft part and the inner shaft part for conducting away cooling fluid supplied to the shaft, wherein: The outer shaft member surrounds a fluid chamber (40), and the fluid chamber is arranged between the inflow portion and the outflow portion in the axial direction; The fluid cavity is used to contain the cooling fluid so as to cool the shaft; and The flow direction of the cooling fluid in the fluid chamber is determined by the delivery direction of the fluid pump (24), It is characterized in that The outer shaft component (32) has a connecting section (38) which connects the outer shaft component to the inner shaft component (30) in a rotationally fixed manner; and The inflow (36) has a channel in the connecting section.

2. The shaft (12) according to claim 1, characterized in that The connecting section (38) has a driving toothing (46) in order to connect the inner shaft part (30) and the outer shaft part (32) to each other in a rotationally fixed manner.

3. The shaft (12) according to claim 1 or 2, characterized in that The outflow portion (42) is formed by a gap between the outer shaft member (32) and the inner shaft member (30).

4. The shaft (12) according to claim 1 or 2, characterized in that The inner shaft part (30) has, in the region of the outflow (42), supporting webs (41) for supporting the inner shaft part on the outer shaft part (32).

5. The shaft (12) according to claim 1 or 2, characterized in that The outflow (42) opens into a supply line to the fluid sump (22).

6. The shaft (12) according to claim 1 or 2, characterized in that An end section of the inner shaft component (30) protrudes further in the axial direction than the outer shaft component (32) to form an output shaft of the electric motor (10).

7. The shaft (12) according to claim 6, characterized in that The end section is connected to the mechanism and / or itself forms a part of the mechanism.

8. The shaft (12) according to claim 1 or 2, characterized in that The outer shaft part (32) consists of two parts, and the two parts (32a, 32b) are connected in a fluid-tight manner by means of compression welding, friction welding and / or bonding.

9. The shaft (12) according to claim 1, characterized in that The channels are designed as punched holes and / or drilled holes.

10. An electric machine (10), comprising: stator (16); a rotor (14); and The shaft (12) according to any one of claims 1 to 9, wherein The shaft is connected to the rotor of the electric machine in a rotationally fixed manner.

11. The electric machine (10) according to claim 10, comprising a sensor wheel (34), characterized in that The sensor wheel rotates with the shaft (12) and includes a hole to allow a cooling fluid (28) to be delivered through the sensor wheel to the shaft.

12. The electric machine (10) according to claim 10 or 11, characterized in that The outer shaft part (32) is connected to the rotor (14) of the electric motor in a rotationally fixed manner by means of a press fit.

13. The electric machine (10) according to claim 10 or 11, characterized in that The motor is operatively connected to a transmission mechanism (44) on the shaft (12); and The outflow (42) delivers cooling fluid (28) to the transmission in order to lubricate and / or cool the transmission.

14. A system (20) for cooling an electric machine (10) according to any one of claims 10 to 13, comprising: a fluid sump (22) for storing a cooling fluid (28); and A fluid pump (24) is used to deliver cooling fluid from the fluid sump to the motor to form a cooling circuit.

15. The system (20) according to claim 14, having a heat exchanger for extracting heat from the cooling fluid (28), characterized in that The heat exchanger is arranged between the fluid sump (22) and the fluid pump (24) along the fluid flow direction.

Images