WO2019081054A1

WO2019081054A1 - Electric motor comprising dual cooling

Info

Publication number: WO2019081054A1
Application number: PCT/EP2018/000477
Authority: WO
Inventors: Nikolai Potozki; Stefanie RIEPE; Heike WEIGEL; Jens Glogowski
Original assignee: Franz Wölfer Elektromaschinenfabrik Osnabrück, Gesellschaft Mit Beschränkter Haftung
Priority date: 2017-10-26
Filing date: 2018-10-22
Publication date: 2019-05-02
Also published as: DE102017009973A1

Abstract

The invention relates to an electric motor (2) comprising: a rotor (8) which is connected to a rotor shaft (10) for conjoint rotation therewith; a housing (4) which is provided with a cooling jacket (12), in particular a cooling jacket through which a fluid can flow and which has an inner jacket (14) and an outer jacket (16); and a stator (6) which is fixed in the housing (4), surrounds the rotor (8) in a circumferential direction and has at least one cooling channel (28) extending substantially axially. The stator (6) contacts the inner jacket (14) of the cooling jacket (12) via a heat transferring contact surface (22), and the contact surface (22) when viewed from an end face of the stator (6), comprises at least 50% of the envelope of the stator (6) and/or the inner face of the inner jacket (14).

Description

Electric motor with dual cooling

The invention relates to an electric motor having a rotor which is connected in a rotationally fixed manner to a rotor shaft, to a housing which is provided with a cooling jacket through which a liquid can flow, which has an inner jacket and an outer jacket, and a stator which is fixedly arranged in the housing. which surrounds the rotor in the circumferential direction and which has at least one substantially axially extending cooling channel.

Such electric motors are known in the art. For example, EP 2 580 848 B1 shows a dynamo-electric machine with air-liquid cooling with a closed air cooling circuit. Here, the inner shell has lugs on which the stator is attached, and cooling fins, where the air is cooled.

A disadvantage of such an electric motor is complicated by the cooling fins and the lugs to be produced inner shell of the cooling jacket. Furthermore, the cooling of the stator takes place primarily by the convective air flow between the inner shell and the stator.

Object of the present invention is to provide an electric motor of the type mentioned with an improved cooling system.

CONFIRMATION COPY The object is achieved by a stator, which contacts the inner jacket of the cooling jacket via a heat-transferring contact surface, the contact surface, viewed from one end side of the stator, comprising at least 50% of the envelope of the stator and / or the inner side of the inner jacket. The envelope means in the context of the invention, the lateral surface of an imaginary cylinder which extends around the stator or within the inner shell and on which the contact surface is arranged. For the calculation of the proportion, the respective smaller lateral surface is used. This causes at least 50% of a circumference, which includes the contact surfaces between the inner shell and stator, an intimate, heat-transferring contact between the stator and the inner jacket of the cooling jacket can be reduced. Excess heat energy can be transported from the stator material via a solid heat pipe into the inner jacket and discharged through the cooling medium circulating in the cooling jacket from the electric motor. For the heat transfer between the solid here in comparison to gases high thermal conductivity of electrically conductive, metallic bodies are used.

Due to the substantially axially extending cooling channel in the stator, a gas or gas mixture such as, for example, air can be guided as a coolant through the stator. In sum, this results in a combined cooling via a convective heat transport through the coolant, in particular in the axially extending cooling channel, and heat removal by heat conduction via the electrically conductive material of the stator or of the inner jacket of the cooling jacket. Thus, can the cooling of the stator and the temperature control in the electric motor, in particular in the region of the stator can be improved.

The axial extent of the cooling jacket preferably corresponds at least to the axial extent of the stator. This ensures that a heat conductive contact not only in individual sections of at least 50% of the envelope of the stator and / or the inside of the inner shell comprises. Rather, this value is valid over the entire length of the stator. Thus, at least 50% of a lateral surface of a cylinder jacket enveloping the stator is in contact with the inside of the inner jacket. As a result, the heat dissipation is ensured by heat conduction from the stator to the inner jacket of the cooling jacket over the entire stator length and thus improved.

Advantageously, at least one stagnation channel forming internals are arranged in the cooling jacket. This results in a guide of the cooling medium, in particular a liquid in the cooling jacket, which causes a targeted and in particular uniform distribution of the cooling medium and thus a uniform cooling of the cooling jacket. Short-circuit flows of the cooling medium and the formation of hotspots, which have excessive temperatures as a result of insufficient overflow with cooling medium, are thus avoided, the flow channel can in this case, for example, have a spiral or meandering course.

Particularly preferably, the internals are spaced apart in the axial direction and extend in the circumferential direction between inner shell and outer coat. The internals each have at least one fluidic passage, wherein the passages of axially successive internals in the circumferential direction are arranged rotated against each other such that the internals in the cooling jacket form a flow channel with multiple deflection and flow division. Such installations, which extend in the circumferential direction between the inner and outer shells, are to be realized in the manufacture of the cooling jacket in a simple manufacturing technology. Through such internals realized flow channels have multiple deflections and flow divisions and mergers of the cooling medium flow. Thus, a distribution of the cooling medium in the cooling jacket is realized in a simple manner and short-circuit currents are prevented. In addition, a homogenization of the cooling medium temperature is achieved by the division of the cooling medium flow and the subsequent remixing. This is particularly advantageous when it comes to the local hotspot formation in the electric motor, whereby two cooling medium streams having a different course in the cooling jacket, have different temperatures. Due to the mixing and repeated division, the temperature of the cooling medium is evened out here.

Particularly preferably, the internals C-shaped extending between the inner shell and outer shell are arranged. Such C-shaped grooves in a particularly simple way have a corresponding fluidic passage and, for example, can be mutually rotated by 180 ° between the inner and outer sheath of the cooling jacket, in order to form a corresponding flow channel. The flow passage is defined by the clearance between the Formed ends of these installations and is thus automatically as high as the distance between the inner and outer sheath. Additional pressure losses are avoided.

Particularly preferably, the internals extend by 270 ° to 350 °, in particular 320 ° to 340 °, between the inner and outer sheath. This ensures that on the one hand there is sufficient guidance of the coolant fluid through the C-shaped internals and, on the other hand, that the pressure loss in the cooling jacket is largely minimized. Particularly preferably, the distance between the two ends of the C-shaped internals is chosen so that the cross section between the two ends of the C-shaped internals between inner and outer shells approximately twice the area as a cross-section in the longitudinal direction of the motor between two directly successive internals , Thus, changes in the dimensions of the flow cross-section are reduced in the cooling jacket and optimized the flow guidance in the cooling jacket.

Advantageously, the electric motor has a fan for generating a coolant flow, in particular a gas or gas mixture stream in an inner space accommodating the stator and the rotor. As a result, a forced convection in the region of the stator and rotor can be generated. This improves the cooling of the rotor and stator and leads to an improved temperature control in the area of the rotor and stator. The fan can in this case be designed as an axial fan, which is arranged in an extension of the axis of rotation of the rotor shaft or as a radial fan, which is offset relative to this axis of rotation, in particular in the radial direction outside of the housing and via a Coolant conductive connection with the interior is in communication. The fan can accelerate the coolant in either the axial or radial direction with respect to the direction of rotation of the fan.

In a preferred embodiment, the fan is rotatably mounted on the rotor shaft. As a result, a coolant flow is continuously generated during operation of the electric motor. Such a fan is automatically in operation when the corresponding electric motor is in operation and rotates the rotor shaft. As a result, a particularly reliable cooling of the electric motor is achieved by the coolant. The structural complexity is relatively low, since a separate drive of the fan is unnecessary.

In an alternative preferred embodiment, the fan has its own and independent of the rotor shaft drive. In this embodiment, the rotational speed of the fan can be controlled independently of the rotational speed of the rotor shaft or of the electric motor. As a result, a better adaptation of the funded by the fan coolant flow on the rotor and stator is ensured. This ensures that evenly high coolant flow is available even at low engine speeds.

Advantageously, the fan is arranged in the interior. Due to the arrangement of the fan in the interior, which also accommodates the stator and rotor of the electric motor, a compact design of a corresponding electric motor can be achieved. be enough. Particularly preferably, the interior is closed. The fan arranged in the interior thus generates a circulation of the coolant in the interior of the electric motor. Characterized in that the interior of the electric motor is separated in the closed version of the environment, an entry of foreign bodies is avoided in the interior. This is particularly important for the use of the electric motor according to the invention in harsh environments with high pollution load or if there is a lot of moisture in the environment. Thus, short circuits in the electrical system in the interior of the electric motor can be avoided. A dissipation of heat from the electric motor takes place in this case almost exclusively by the coolant jacket flowing through the cooling medium.

Advantageously, the rotor has at least one substantially axially extending cooling channel. Through this cooling channel and the rotor can be flowed through by the coolant and cooled accordingly. The temperature control of the electric motor is thus improved. Such a cooling channel extending in the rotor is particularly advantageous in electric motors with a closed interior, since the coolant flow generated by the fan can thus form a cooling circuit which comprises the cooling channel in the rotor and the cooling channel in the stator, so that the coolant flows via the one cooling channel from the fan away and back to the fan via the other cooling channel. By such a circulating coolant flow in the interior of the electric motor, the cooling and thus the temperature control in the interior of the electric motor is improved. Preferably, the electric motor has a cooling control, which comprises at least one sensor unit and is designed to control the cooling of the electric motor. In this case, the at least one sensor unit can be arranged in the interior of the electric motor, on the stator, on the rotor or in the region of the cooling medium inflow or cooling medium outflow of the cooling jacket or at another suitable location. The sensor unit can measure, for example, the flow rates or pressure losses. However, the sensor unit particularly preferably absorbs the temperature. The cooling control evaluates the signal of the sensor unit and controls the cooling of the electric motor accordingly. Particularly preferably, the cooling control is designed so that it controls the flow through the cooling jacket. Thus, the need for cooling medium as well as the energy needed to deliver the cooling medium through the cooling jacket can be adjusted to the current cooling requirements of the electric motor. Particularly preferably, the electric motor to the fan with its own, independent of the rotor shaft drive, wherein the cooling control is designed to control the speed of the fan. Thus, the flow of the coolant in the region of the stator and rotor can be controlled and adapted to the current coolant requirement. Thus, the energy required for the drive of the fan is optimized and ensures always sufficient cooling of the rotor and stator via the coolant.

Particularly preferably, the sensor unit is arranged in the interior of the electric motor. In this case, it may in particular be arranged directly on the stator or on the rotor and directly record the temperatures of these components. Further advantageous embodiments of the invention will be explained in more detail with reference to the embodiments illustrated below. Show:

1 shows a cross section in the longitudinal direction through an inventive

Electric motor;

FIG. 2 shows a cross-section at right angles to the longitudinal central axis of the electric motor according to FIG. 1; FIG.

FIG. 3 shows a view of the housing of the electric motor according to the invention according to FIG. 1 with the stator; FIG.

Fig. 4 is a view of the housing with the stator of Figure 3 taken along the longitudinal center axis.

5 shows a view of a rotor of an electric motor according to the invention from the end face;

FIG. 6 shows the longitudinal cross section of the rotor according to FIG. 5; FIG.

7 shows the inner jacket of a cooling jacket of an electric motor according to the invention with internals;

8 shows the housing according to FIG. 7 in a view from the side, FIG. Fig. 9 shows the cross section through the housing of FIG. 8, and

10 shows a housing in an alternative embodiment.

Hereinafter, equivalent elements of the invention are given a common reference numeral. The features of the exemplary embodiments described below can also be the subject of the invention in other combinations of features.

1 shows an electric motor 2 with a housing 4, in which a stator 6 is arranged, which comprises a rotor 8. The rotor 8 is rotatably connected to a rotor shaft 10. The housing 4 has a cooling jacket 12 which has an inner jacket 14 and an outer jacket 16. In the cooling jacket 12, internals 18 are fitted between the inner jacket 14 and the outer jacket 16, through which flow channels 20 are formed in the cooling jacket 12. Through the flow channels 20, a cooling medium can be passed through the cooling jacket 12. The stator 6 is connected via a heat-transferring contact surface 22 in a heat-conducting contact with the inner jacket 14 of the cooling jacket 12. In this way, excess energy can be discharged from the stator 6 to the cooling jacket 12 and discharged there by the cooling medium from the electric motor 2.

The stator 6 and the rotor 8 are arranged in an inner space 24 of the electric motor 2. On the rotor shaft 10, a fan 26 is rotatably disposed. Through this Fan is a coolant in the interior 24 upon rotation of the rotor shaft 10 is set in motion and flows through cooling channels 28 in the stator 6 and cooling channels 30 in the rotor 8 in the interior 24 on the stator 6 and rotor 8 over and cools them.

Fig. 2 shows an electric motor according to Fig. 1 in a cross section. Here, the cooling channels 28 of the stator 6 and the cooling channels 30 of the rotor 8 are clearly visible. In the cooling jacket 12 internals 18 can be seen. The internals 18 each have a passage 32 through which the areas separated by the internals in the axial direction are in fluid communication.

FIG. 3 shows the housing 4 of the electric motor with the cooling jacket 12 comprising the inner jacket 14 and the outer jacket 16, in which the internals 18 form flow channels 20. In the housing 4, a stator 6 is arranged. Fig. 4 shows the housing 4 with the stator 6 arranged therein in a view from the front side. The cooling channels 28 in the stator 6 are clearly visible. In this embodiment, the cooling channels 28 are mounted on the edge of the stator 6. An envelope of the stator coincides more than 50% with the contact surface 22 between the stator 6 and the inner jacket 14 of the cooling jacket 12 together. As a result, a large area is provided for heat transfer from the stator 6 into the cooling jacket 12 via solid-state heat conduction. The cooling channels 28 in the stator 6 can in this case also be arranged in the stator 6 in such a way that the outside of the stator 6 abuts the entire surface of the inner jacket 14 of the cooling jacket 12. The cooling channels 28 in the stator 6 then run not only along the stator 6 but within the stator 6. The rotor 8 is shown in Fig. 5 in a view from the front side, in which the cooling channels 30 of the rotor 8 can be clearly seen. Fig. 6 shows the same rotor 8 with the cooling channel 30 in a cross section.

Fig. 7 shows a part of the housing 4, with the inner shells 14 of the cooling jacket 12, are fixed to the fixtures 18. The baffles 18 are in this case designed as C-shaped elements extending in the circumferential direction around the inner shell. Between the ends of the C-shaped internals 18, a passage 32 is formed, through which the areas defined by the internals are in a fluidic connection. In this case, it is easy to see how the internals 18 in the cooling jacket 12 form a flow channel 20, in which a multiple deflection and current division of the cooling medium and a back mixing of the cooling medium takes place. FIG. 8 shows this part of a housing 4 with the inner jacket 14 of the cooling jacket 12 and the internals 18 arranged on the inner jacket 14. FIG. 9 shows the housing in a section which is laid through the apertures 32 of the fixtures 18. It can be seen that the C-shaped internals are mutually offset by 180 ⁰ offset.

10 shows a housing 4 in an alternative embodiment with a fan 26 arranged outside an interior 24. The fan 26 has a separate drive, which is designed here as an electric motor. The coolant is sucked in from outside the electric motor 2 through a filter and discharged back to the outside through an outlet opening after flowing through the interior 24 which is open to the outside. By an arrangement of the fan 26 outside the interior 24 can be realized in comparison with an arrangement of the fan 26 in the interior shorter overall length of the electric motor 2.

Claims

claims

1 . Electric motor (2) having a rotor (8) which is connected in a rotationally fixed manner to a rotor shaft (10), having a housing (4) which is provided with a cooling jacket (12), in particular through which a liquid can flow, which has an inner jacket (14) and an outer jacket (16), and having a stator (6) arranged fixedly in the housing (4), which surrounds the rotor (8) in the circumferential direction and which has at least one substantially axially extending cooling channel (28),

characterized in that

the stator (6) contacts the inner jacket (14) of the cooling jacket (12) via a heat-transmitting contact surface (22), the contact surface (22), viewed from one end side of the stator (6), covering at least 50% of the envelope of the stator (6). and / or the inside of the inner jacket (14).

2. Electric motor (2) according to claim 1, characterized in that the axial extent of the cooling jacket (12) corresponds at least to the axial extent of the stator (6).

3. Electric motor (2) according to claim 1 or 2, characterized in that in the cooling jacket (12) at least one flow channel (20) forming internals (18) are arranged.

4. Electric motor (2) according to claim 3, characterized in that the internals (18) are spaced apart in the axial direction and extend in the circumferential direction between the inner shell (14) and outer shell (16), wherein the internals (18) respectively have at least one fluidic passage (32) and wherein the passages (32) of axially successive internals (18) in the circumferential direction are rotated against each other such that the internals (18) in the cooling jacket (12) has a flow channel (20) train multiple diversion and stream division.

5. Electric motor (2) according to claim 4, characterized in that the internals (18) C-shaped between the inner shell (14) and outer jacket (16) extending arranged.

6. Electric motor (2) according to claim 5, characterized in that the internals (18) by 270 ° to 350 °, in particular 320 ° to 340 °, between the inner shell (14) and outer jacket (16) extending are arranged.

7. Electric motor (2) according to one of the preceding claims, characterized in that the electric motor (2) has a fan (26) for generating a coolant flow, in particular a gas or gas mixture stream, in a stator (6) and the rotor (8 ) receiving interior (24).

8. Electric motor (2) according to claim 7, characterized in that the fan (26) rotationally fixed on the rotor shaft (10) is arranged.

9. Electric motor (2) according to claim 7, characterized in that the fan (26) has its own and of the rotor shaft (10) independent drive.

10. Electric motor (2) according to one of claims 7 to 9, characterized in that the fan (26) in the interior (24) is arranged.

1 1. Electric motor (2) according to claim 10, characterized in that the interior space (24) is closed.

12. Electric motor (2) according to one of the preceding claims, characterized in that the rotor (8) has at least one substantially axially extending cooling channel (30).

13. Electric motor (2) according to one of the preceding claims, characterized in that the electric motor (2) has a cooling control, which comprises at least one sensor unit and the cooling of the electric motor (2) is formed controlling.

14. Electric motor (2) according to claim 13, characterized in that the cooling control is designed to control the flow through the cooling jacket (12).

15. Electric motor (2) according to claim 9 and one of claims 13 or 14, characterized in that the cooling control is designed to control the speed of the fan (26).

16. Electric motor (2) according to one of claims 13 to 15, characterized in that the sensor unit in the interior (24) is arranged.