Cooling device for an electric motor, in particular an EC motor, as well as electric motor, in particular EC motor

Abstract

The cooling device is designed for an electric motor, in particular an EC motor. To significantly increase heat dissipation in a structurally simple manner, the cooling device has at least two coaxially spaced annular walls that define an annular channel for cooling air and are connected to each other by connecting elements distributed around the circumference. The annular channel has an inlet and an axially opposite outlet for the cooling air. The cooling device ensures high heat dissipation. This results in higher performance of the electric motor when the limit temperature is reached. The cooling air can be directed precisely between the two coaxially spaced annular walls to adequately cool the electric motor or parts thereof.The cooling device can be used as an additional component that can be connected to the electric motor in such a way that the parts of the electric motor exposed to the cooling air are properly covered.

Description

[0001] The invention relates to a cooling device for an electric motor, in particular an EC motor, according to claim 1 and to an electric motor, in particular an EC motor, according to claim 12.

[0002] During operation, the electric motor generates heat that must be dissipated to prevent excessive heating of individual components or the entire electronic assembly within the electric motor. To prevent excessive heat buildup, i.e., to ensure that a temperature limit is not exceeded or can still be sufficiently dissipated, the electric motor's full capacity is not utilized. Current heat dissipation measures are insufficient and / or result in an increase in the heat dissipated per unit of time by the electric motor or the unit it drives and / or in increased noise.

[0003] The invention is based on the object of designing the cooling device and the electric motor in such a way that the heat dissipation can be significantly increased in a structurally simple manner without the emitted acoustics assuming excessively high values.

[0004] This object is achieved in the cooling device with the features of claim 1 and in the generic electric motor with the characterizing features of claim 12.

[0005] The cooling device according to the invention ensures that high heat dissipation is achieved. This makes it possible for the electric motor to provide a higher effective power. The cooling device ensures that the power density of the motor is increased while maintaining or reducing acoustics, and the effective power is increased accordingly. This in turn leads to the advantage that the volume flows and pressure increases and thus also the characteristic curve of a fan driven by the electric motor can be increased. The cooling device leads to higher performance of the electric motor when the limit temperature is reached. The cooling air can be directed between the two coaxial annular walls in such a way that the electric motor or parts of it can be sufficiently cooled. The annular duct has an inlet and an axially opposite outlet for the cooling air.The cooling device can be used as an additional component that can be connected to the electric motor in such a way that the parts of the electric motor that are to be exposed to the cooling air are perfectly covered.

[0006] The two ring walls bordering the annular channel advantageously run parallel to each other over at least part of their axial height. This ensures that the cooling air is guided within the annular channel. The cooling air can be guided within the annular channel with the help of the ring walls in such a way that the cooling air reliably reaches the parts of the electric motor that need to be cooled.

[0007] In an advantageous embodiment, the inner annular wall forms a mount with which the cooling device can be attached to a rotor of the electric motor. In this case, the cooling device rotates with the rotor, thereby easily achieving a high cooling air flow rate, which leads to very effective heat dissipation from the electric motor.

[0008] The cooling device forms an axial cooling air ring, which guides the cooling air in the axial direction of the electrical enclosure. "Axial" here does not simply mean a purely axial cooling air flow. Rather, it expresses the fact that the cooling air flows in the axial direction of the enclosure. Depending on the enclosure design, the flow direction may also be at least partially oblique to the axial direction.

[0009] The connecting elements that connect the two ring walls can run radially.

[0010] However, depending on the design of the cooling device, it is also possible to provide the connecting elements in such a way that they are arranged at an angle other than 90° to the radial direction of the cooling device.

[0011] The connecting elements are advantageously blades that are angled to the flow direction of the cooling air within the annular channel. Depending on the angle of attack, the cooling air enters the annular channel either via the inlet or outlet. The angle of attack of the blades can be selected so that a desired volume flow through the annular channel is easily achieved. This makes it easy to achieve high cooling and thus heat dissipation.

[0012] In an advantageous embodiment, the inner annular wall and the outer annular wall each have at least one conical section. In the conical annular space section thus formed, the cooling air can be directed in a targeted manner to the area of ​​the electric motor housing that is to be cooled.

[0013] Advantageously, the connecting elements, which run at an angle to the radial plane, are located in the area of ​​the conical sections of at least one ring wall. In this conical area, the connecting elements can easily achieve a desired high volume flow of cooling air.

[0014] The outer ring wall is advantageously provided with a circumferential collar at the end. This collar is advantageously cylindrical and advantageously adjoins the conical section of the outer ring wall axially.

[0015] The surrounding collar forms a nozzle with which the cooling air can be directed specifically to the area of ​​the electric motor housing that is to be cooled.

[0016] The outer collar of the outer ring wall advantageously projects axially beyond the inner ring wall.

[0017] The electric motor according to the invention is characterized in that the cooling device is mounted on the rotor in a rotationally fixed and axially fixed manner. As a result, the cooling device rotates together with the rotor, enabling reliable cooling of at least parts of the electric motor housing.

[0018] Since the cooling device is located on the rotor, it can be retrofitted even to electric motors that are already in use.

[0019] Advantageously, the inner annular wall of the cooling device is mounted on the rotor and surrounds it. The inner annular wall thus not only serves to form the annular channel for the cooling air, but also serves as a mounting means for connecting the cooling device to the rotor.

[0020] The cooling device is mounted on the rotor in such a way that the cooling air entering or exiting the annular channel flows axially through the stator's cooling fins. Whether the cooling air exits or enters the annular channel depends on the position of the blade-shaped connecting elements in the annular channel. In either case, the cooling air flows through the stator's cooling fins, thereby significantly increasing heat dissipation.

[0021] The cooling fins alone ensure that the heat generated during operation of the electric motor can be dissipated. In conjunction with the cooling air, the heat dissipation performance is significantly increased.

[0022] The flange of the outer ring wall advantageously extends axially beyond the cooling fins. This ensures that the cooling air is smoothly directed through the cooling fins, ensuring optimal cooling.

[0023] The subject matter of the application arises not only from the subject matter of the individual patent claims, but also from all information and features disclosed in the drawings and the description. Even if they are not the subject matter of the claims, they are claimed as essential to the invention insofar as they are novel, individually or in combination, over the prior art.

[0024] Further features of the invention emerge from the further claims, the description and the drawings.

[0025] The invention will be explained in more detail with reference to some embodiments shown in the drawings. Fig. 1 shows in axial section a first embodiment of a cooling device according to the invention, Fig. 2 a view in the direction of arrow II in Fig. 1, Fig. 3 the cooling device according to the invention according to Fig. 1 in perspective view, Fig. 4 to Fig. 6 in representations according to the Fig. 1 to 3 a second embodiment of a cooling device according to the invention, Fig. 7 to Fig. 9 in representations according to the Fig. 1 to 3 a third embodiment of a cooling device according to the invention, Fig: 10 in schematic representation and in axial section a cooling device provided on an electric motor, Fig. 11 in perspective view the stator with cooling device according to Fig. 10.

[0026] The cooling system described below ensures optimal heat dissipation from individual components or the entire electronics of an EC motor while maintaining the acoustic emissions of the overall system. The cooling system generates an axial airflow from the rotor or impeller to the stator or motor, or vice versa. This airflow is directed by the air conveyor system so that it is directed over the cooling fins in the stator housing. This achieves optimal cooling of the EC motor in a structurally simple yet effective manner.

[0027] The cooling system according to the Fig. 1 to 3 has a guide body 1, which advantageously has a circular outline. The guide body 1 has a cylindrical section 2 that extends from one end of the guide body 1 and merges into a radially outwardly expanding intermediate section 3. The transition is continuously rounded.

[0028] At its end facing away from the cylindrical section 2, the intermediate section 3 continuously curves into a cylindrical end section 4 which defines a circular opening 5.

[0029] In the exemplary embodiment, the cylindrical section 2 has an axial width 6 which is greater than the axial width 7 of the intermediate section 3.

[0030] The cylindrical end section 4 has an axial width 8 which is substantially smaller than the axial widths 6, 7 of the cylindrical section 2 and the intermediate section 3.

[0031] However, the axial widths 6 to 8 described are only examples and do not represent a mandatory requirement. Depending on the design of the cooling system and the intended application, the axial widths may also vary, even in relation to one another.

[0032] The sections 2 to 4 of the guide body 1 are advantageously formed in one piece with each other and are preferably made of a hard plastic, advantageously of an injection-moldable plastic.

[0033] The intermediate section 3 has a wall thickness that initially increases steadily from the cylindrical section 2 and decreases again toward the cylindrical end section 4. The wall thickness change of the intermediate section 3 advantageously occurs continuously.

[0034] The cylindrical section 2 has a smaller wall thickness than the intermediate section 3 and the cylindrical end section 4. An air guide body 9, which has air guide elements 10, is connected to the end of the cylindrical section 2 facing away from the cylindrical end section 4.

[0035] The air guide body 9 can be connected to the free end of the cylindrical section 2 in any suitable manner, for example glued, welded and the like.

[0036] The air guide body 9 with the air guide elements 10 is advantageously made in one piece from a suitable plastic, but can of course also be made in several parts.

[0037] The air guide body 9 has a cylindrical outer ring 11, which has a larger inner and outer diameter than the section 2 of the guide body 1. The outer diameter of the outer ring 11 can advantageously correspond to the outer diameter of the cylindrical end section 4 of the guide body 1. The air guide elements 10 are evenly distributed over the circumference of the outer ring 11 and, in axial view ( Fig. 2) are arranged next to each other at a distance. The air guiding elements 10 are of the same design and are wound across their radial width ( Fig. 1 and Fig. 3).

[0038] The air guide elements 10 connect the outer ring 11 to an inner ring 12, which is coaxial with the outer ring 11 and has approximately the same inner and outer diameters as the cylindrical section 2 of the guide body 1. Air passages 13 are formed between the blade-shaped air guide elements 10, through which the air flows during use of the cooling device to improve the heat dissipation of individual components or the entire electronic assembly of the electric motor.

[0039] The guide body 1 is firmly connected to the inner ring 12 of the air guide body 9 via its cylindrical section 2. The cylindrical inner wall 14 of the inner ring 12 advantageously lies flush with the inner wall 15 of the end section 4. This eliminates any disturbing step at the transition from the end section 4 of the guide body 1 to the inner ring 12 of the air guide body 9, which would impede the flow of cooling air and / or lead to undesirable noise.

[0040] The two rings 11, 12 of the air guide body 9 are designed such that they axially project beyond the air guide elements 10 which are wound over their radial length.

[0041] The rings 11, 12 form the annular walls of an annular channel 44 through which the cooling air flows. It has an inlet 45 and an axially opposite outlet 46 for the cooling air. The annular channel 44 has a constant cross-section across its width and circumference.

[0042] As from Fig. 1, the outer ring 11 has a greater axial length than the inner ring 12. Therefore, the outer ring 11 surrounds the cylindrical section 2 of the guide body 1 with its area facing the opening 5 of the guide body 1. At the other end, the circumferential edges 16 and 17 of the outer ring 11 and the inner ring 12 lie in a common radial plane ( Fig. 1).

[0043] Protruding from the inner wall 14 of the inner ring 12 are raised portions 18 distributed around the circumference. These raised portions extend in the circumferential direction and are advantageously equally spaced from one another. The raised portions 18 are narrow and improve the fit of the cooling device on the electric motor.

[0044] The cooling device described, which is designed as an axial cooling ring, generates an air flow in the axial direction from the rotor / impeller to the stator / motor or vice versa. The air flow is blown through radially extending cooling fins of the stator housing, creating a convective cooling flow across the cooling fins. This achieves excellent heat dissipation on the electric motor. This is demonstrated by the Fig. 10 and Fig. 11 will be explained in more detail.

[0045] The cooling device is mounted non-rotatably on the rotor 33 ( Fig. 10 and Fig. 11) of the electric motor, so that it rotates around its axis together with the rotor 33 during operation of the electric motor and generates the air flow. The cooling device is arranged on the rotor 33 near the cooling fins 37 of the stator housing such that the air guide body 9 with the air guide elements 10 is located adjacent to the cooling fins 37 of the stator housing. This ensures reliable air flow through the cooling fins 37 of the stator housing.

[0046] The Fig. Figures 4 to 6 show a further embodiment of the cooling device. In contrast to the previous embodiment, the air guiding elements 10 are not arranged radially, but form an angle with the radial direction ( Fig. 4). The air guide elements 10 connect the outer ring 11 to the inner ring 12 and are advantageously formed integrally with them. The outer ring 11 has a conical surface 11a, which adjoins a cylindrical edge portion 19 at its smaller diameter end.

[0047] The inner ring 12 has a conical surface 20, which advantageously runs parallel to the conical surface 11a and, at its larger diameter end, merges into a cylindrical edge section 21. It has an axial width 22, which in the exemplary embodiment is smaller than the axial width 23 of the conical surface 20. Here, too, the specified width ratios are to be regarded only as examples and not as mandatory specifications.

[0048] The cylindrical edge section 19 of the outer ring 11 projects axially beyond the conical surface 20 of the inner ring 12 ( Fig. 4).

[0049] In the cylindrical edge section 21, open-edge recesses 24 are provided distributed over the circumference, which advantageously have a rectangular outline.

[0050] The recesses 24 are adapted to the installation conditions on the electric motor housing and can also have any other outline shape.

[0051] Furthermore, the edge portion 21 can also be provided without the recesses 24 and connected to the rotor of the electric motor in another way.

[0052] The cooling device is advantageously made in one piece from a suitable hard plastic. The outer ring 11 and the inner ring 12 overlap each other in the axial direction, so that the cooling device has only a small axial width. It can therefore also be used where limited installation space is available.

[0053] Between the blade-shaped air guide elements 10 are the air passages 13, through which the cooling air can reach the cooling fins 37 of the stator 32. The cooling air flow can flow between the conical shells 11a, 20 and through the air passages 13 between the air guide elements 10 to the cooling fins 37 of the stator 32. The cylindrical edge section 19 of the outer ring 11 protrudes axially by a distance of 25 mm beyond the adjacent end of the conical shell 20 of the inner ring 12. In this area, the cooling air can therefore flow into or out of the cooling device in a manner to be described below. The two rings 11, 12 guide the cooling air to the cooling fins 37 of the stator 32, which can be reliably cooled in this way.

[0054] The conical shell 20 of the inner ring 12 has projections 27 on its outer side 26 distributed over the circumference, which have, for example, a rectangular outline and serve to support fastening screws which pass through openings 31 ( Fig. 5) are inserted into the conical shell 20 and screwed into threaded holes on the rotor 33.

[0055] The embodiment according to the Fig. 7 to 9 differs from the embodiment according to the Fig. 4 to 6 essentially only in that there are no air guiding elements between the two rings 11, 12. In this case, the cooling device has no vane-shaped elements with which a volume or cooling flow could be actively generated during use.

[0056] The outer ring 11 and the inner ring 12 are connected to each other by radially extending connecting elements 28, which advantageously have a round cross-section, which is optimal for good air flow. The connecting elements 28 can have a circular cross-section. However, the cross-section of the connecting elements 28 is advantageously oval, allowing the cooling air flow to flow optimally past the connecting elements 28.

[0057] The connecting elements 28 are advantageously provided near the transition from the conical shell 20 to the edge section 21 of the inner ring 12.

[0058] It is advantageous if the conical shell 11a of the outer ring 11 merges at its end facing away from the edge section 19 into a cylindrical end section 29, to the inner side 30 of which the connecting elements 28 are connected.

[0059] The conical shell 20 of the inner ring 12 is provided, in accordance with the previous embodiment, on its outer side 26 facing away from the outer ring 11 with the projections 27 which are at the level of the through openings 31 ( Fig. 8 and Fig. 9), through which fastening screws are inserted, with the aid of which the cooling device can be attached to the rotor 33 of the electric motor. The fastening screws protrude, as described, through the projections 27 into corresponding threaded holes in the rotor 33 of the electric motor. The projections 27 ensure sufficient hold of the fastening screws on the inner ring 12.

[0060] The Fig. 10 and Fig. Figure 11 schematically shows an electric motor with a stator 32 and a rotor 33, which is driven to rotate about its axis. The stator 32 and the rotor 33 are shown only schematically. A fan wheel 34 is connected to the rotor 33 in a rotationally fixed manner.

[0061] The cooling device is located on the rotor 33 and is connected to the rotor 33 in a rotationally fixed manner.

[0062] The Fig. 10 and Fig. 11 show the cooling device according to the embodiment according to the Fig. 7 to 9. The air guidance devices according to Fig. 1 to 6 are equally fixed to the rotor 33.

[0063] The stator 32 has a stator housing 35 with a circumferential radial flange 36, on which radially outwardly extending cooling fins 37 are provided. These can be designed as straight cooling fins, each located in a radial plane. However, such straight cooling fins can also be provided on the radial flange 36, extending at an angle to the radial direction. In the illustrated embodiment, the cooling fins 37 are wave-shaped along their length.

[0064] It is also possible to provide cooling fins of different shapes and / or running in different directions over the circumference of the radial flange 36.

[0065] The cooling device is mounted so that the cylindrical edge section 19 covers the cooling fins 37 circumferentially, preferably projecting axially. Fig. As shown in Figure 10, the edge section 19 protrudes beyond the side of the cooling fins 37 facing away from the rotor 33. This edge section 19 forms a circumferential nozzle, which directs the air flow over the stator-side cooling fins 37. At the same time, the radiated sound power is reduced.

[0066] The cooling device conveys the air flow in the axial direction from the rotor 33 or the fan wheel 34 to the stator 32 or vice versa. The flow direction is in the Fig. 10 and Fig. 11 is indicated by a corresponding flow arrow 38.

[0067] The fan impeller 34 is a radial fan impeller that generates a radial primary volume flow 39. This air flows radially out through a base plate 40 of the fan impeller 34. The base plate 40 is connected in a known manner to a cover plate 42 via fan blades 41. The base plate 40, the fan blades 41, and the cover plate 42 are advantageously formed in one piece, in particular from an injection-moldable plastic.

[0068] The volume flow 39 ensures a secondary flow between the base plate and the stator 32 or the cooling device. The conical surface 20 of the inner ring 12 and the conical surface 11a of the outer ring 11 form a conical annular flow channel 44. As a result, centrifugal forces act on the air flow flowing through the flow channel 44 during the rotation of the cooling device, leading to the formation of the secondary flow 43.

[0069] Since the cooling device does not have any air guiding elements, the airflow flowing over the cooling fins 37 is generated passively in the manner described. The cooling device thus serves exclusively to guide the air over the cooling fins 37.

[0070] If the cooling system is installed in accordance with Fig. 1 to 6 are used, then the cooling air flow which flows over the cooling fins 37 is actively generated as a result of the blade-shaped air guide elements 6.

[0071] The air guiding elements 10 form a blading system, with which the cooling flow is actively generated when the rotor 33 and thus the cooling device rotate. Depending on the position of the air guiding elements 10, the cooling flow is generated by suction or pressure. In suction generation, the air flow 38 is sucked in from the stator side and guided over the cooling fins 37 ( Fig. 10 and Fig. 11).

[0072] In the push-pull design, the air flow flowing over the cooling fins 37 is drawn in from the area between the base plate 40 and the cooling device and directed at least approximately outward (push-pull) on the stator side. The direction in which the cooling air flow flows over the cooling fins 37 depends on the positioning or arrangement of the air guide elements 10 between the outer ring 11 and the inner ring 12.

[0073] By using the described cooling devices, air flows around the stator housing 35, effectively dissipating heat. This allows electronics housed in the electronics housing 32 to deliver high performance with virtually the same acoustics. By utilizing the permissible limit temperatures, the performance can be increased. This allows for larger volume flows and pressure increases, and thus the characteristic curve of the fan with the impeller 34 to be increased.

[0074] Tests have shown that, at given operating temperatures, the cooling system can increase the speed of the electric motor, resulting in improved motor utilization. Acoustic values ​​remain low, so the fan equipped with the cooling system produces only minimal operating noise.

Claims

[1] Cooling device for an electric motor, in particular an EC motor, characterized by that the cooling device has at least two annular walls (11, 12) which are coaxially arranged at a distance from one another and which delimit an annular channel (44) for cooling air and are connected to one another by connecting elements (10, 28) arranged distributed over the circumference, and that the annular channel (44) has an inlet (45) and an axially opposite outlet (46) for the cooling air. [2] Cooling device according to claim 1, characterized by that the two ring walls (11, 12) run parallel to each other over at least part of their height. [3] Cooling device according to claim 1 or 2, characterized by that the inner ring wall is a holder for fastening the cooling device to a rotor (33) of the electric motor. [4] Cooling device according to one of claims 1 to 3, characterized by that the connecting elements (10, 28) run radially. [5] Cooling device according to one of claims 1 to 3, characterized by that the connecting elements (10) are arranged at an angle different from 90° to the radial direction. [6] Cooling device according to one of claims 1 to 5, characterized by that the connecting elements (10) are blades which are inclined to the flow direction of the cooling air. [7] Cooling device according to one of claims 1 to 6, characterized by that the inner ring wall (12) and the outer ring wall (11) each have at least one conical section (11a, 20). [8] Cooling device according to claim 7, characterized by that the obliquely extending connecting elements (10) are provided in the region of the conical sections (11a, 20) of the at least one annular wall (11, 12). [9] Cooling device according to one of claims 1 to 8, characterized by that the outer ring wall (11) has a circumferential collar (19) at the end. [10] Cooling device according to claim 9, characterized by that the collar (19) is axially connected to the conical section (11a) of the outer ring wall (11). [11] Cooling device according to claim 9 or 10, characterized by that the collar (19) of the outer ring wall (11) projects axially beyond the inner ring wall (12). [12] Electric motor, in particular EC motor, with a stator (32) and a rotor (33), characterized by that the cooling device according to one of claims 1 to 11 is fastened on the rotor (33) in a rotationally fixed manner. [13] Cooling device according to claim 12, characterized by that the inner annular wall (12) of the cooling device surrounds the rotor (33) and is fastened to it. [14] Cooling device according to claim 12 or 13, characterized by that the cooling device is fastened to the rotor (33) in such a way that the cooling air emerging from or flowing into the annular channel (44) flows axially through cooling fins (37) of the stator (32). [15] Cooling device according to one of claims 12 to 14; characterized bythat the collar (19) of the outer ring wall (11) projects axially beyond the cooling fins (37).

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