Device for measuring the temperature of an electric machine

Abstract

The invention relates to a device for measuring the temperature of an electric machine (10), the stator (22) of which is enclosed by a housing (12) and the stator (22) is electrically contacted by means of U, V, W busbars (14, 16, 18). The U, V, W busbars (14, 16, 18) are mounted on a connector rail (30), and the temperature of the electric machine (10) is detected by at least one temperature sensor (24, 26). The preferably single temperature sensor (24) is thermally connected to a voltage-free, passive conductor (42) containing a metallic material and mounted on the connector rail (30). Furthermore, the invention relates to the use of the device for measuring the temperature of an electric machine (10), particularly in the region of the stator (22) of the electric machine (10).

Description

Technical area

[0001] The invention relates to a device for measuring the temperature of an electrical machine whose stator is enclosed in a housing and the stator is electrically contacted by means of U-, V-, and W-type busbars mounted on a connector rail, and the temperature of the electrical machine is detected by at least one temperature sensor. Furthermore, the invention relates to the use of the device for detecting the temperature of an electrical machine, in particular the stator of the electrical machine. State of the art

[0002] Electrical machines, such as electric motors, are equipped with one or more temperature sensors to measure the temperature of the electrical machine, particularly in the area of ​​the stator winding. To increase the accuracy of temperature measurement, at least one temperature sensor is located directly on the winding head to measure the temperature as accurately as possible and protect the electrical machine from overheating.

[0003] However, due to the risk of short circuits, the temperature sensors cannot be placed directly on the stator winding. Therefore, a minimum distance must be maintained, which is filled with a potting compound in which the stator winding is embedded, which inevitably distorts the measurement results.

[0004] Furthermore, the temperature sensor(s) are fitted with a stocking and then a metal sleeve, which further distorts the measurement results. Finally, connecting the temperature sensors requires the installation of expensive twisted cables, which is both very complex and appears unsuitable for injection molding with high injection pressures.

[0005] Since the installed temperature sensors occasionally fail, even though they are encapsulated in the stator winding's potting compound, the entire stator or stator winding must be disposed of and replaced in such cases, as the temperature sensors encapsulated in the potting compound are generally not removable. A connection point between the power electronics and the electrical machine is realized by plug-in contacts, which are subjected to a very complex testing procedure. Overall, this type of temperature measurement design, as described above, is very costly, difficult to disassemble, and cannot be considered robust over its service life. Description of the invention

[0006] According to the invention, a device for measuring the temperature of an electrical machine is proposed, the stator of which is enclosed in a housing. The stator is electrically contacted by means of U-, V-, and W-type busbars mounted on a connector rail, and the temperature of the electrical machine is detected by at least one temperature sensor. The at least one temperature sensor is connected in a thermally conductive manner to a voltage-free, passive conductor containing a metallic material and mounted on the connector rail.

[0007] The arrangement of the at least one temperature sensor makes it easy to replace it in the event of a failure, since the at least one temperature sensor is located outside the stator winding or outside the housing of the electrical machine.

[0008] In an advantageous development of the device proposed according to the invention, the passive conductor comprises a sleeve attachment which is part of a heat conduction path.

[0009] In an advantageous development of the device proposed according to the invention, a support arrangement is fastened to the sleeve attachment, which is made of a heat-conducting material, in particular as a copper sheet or as an aluminum component.

[0010] In the device proposed according to the invention, the support assembly comprises a first and a second leg, which are arranged essentially at right angles to each other. It is also possible to design other geometries of the support assembly, which preferably accommodates a temperature sensor.

[0011] In the device proposed according to the invention, at least the support assembly, with the temperature sensor preferably arranged thereon, is provided with an overmolding, in particular made of a plastic material, serving as thermal insulation. Instead of just the support assembly, however, other parts of the heat conduction path, in particular the sleeve attachment and the passive conductor, can also be provided with an overmolding made of a plastic material. This depends on the requirements regarding measurement accuracy.

[0012] In the device proposed according to the invention, the sleeve extension is provided with a continuous helix along its outer surface. The helix advantageously enables the compensation of tolerances between the busbars of an inverter or power electronics and the stator of the electrical machine, taking into account the respective required current-carrying capacity.

[0013] The device proposed according to the invention is advantageously designed such that the at least one temperature sensor, preferably the first and the second temperature sensor, are connected to an interface of a printed circuit board (PCB).

[0014] Furthermore, the device proposed according to the invention is characterized in that the busbar, to which the passive conductor is thermally connected, has a sleeve extension (crimp sleeve). The busbar with sleeve extension - serving here as a passive conductor - represents a common part to avoid variances. Ideally, the busbar with sleeve extension, which is a passive conductor, is structurally identical to the U-, V-, and W-type busbars already installed on the stator, thus ensuring the use of common parts and thus a reduction in costs. The passive conductor allows for a largely undisturbed and, in particular, uninterrupted heat conduction path to the preferably one temperature sensor. In an advantageous embodiment of the device proposed according to the invention, the preferably one temperature sensor is arranged outside the housing and outside the stator of the electrical machine.This significantly improves accessibility and replacement of the temperature sensor in the event of a failure. The components of the electric machine, especially the stator winding and housing, can be reused.

[0015] Furthermore, the invention relates to the use of the device for detecting the temperature of an electrical machine, in particular for detecting the temperature of a stator winding of an electrical machine. Advantages of the invention

[0016] The solution proposed by the invention advantageously avoids the need to embed temperature sensors in a potting compound on the housing. Since the at least one temperature sensor, preferably the first and second temperature sensors, are arranged outside the housing or outside the stator winding or the winding heads, easy access is provided, allowing for easy replacement of the respective temperature sensor(s) in the event of a failure. In contrast to the prior art, there is no need to dispose of the entire stator, since if the temperature sensors are embedded in a potting compound, they are generally not removable.

[0017] The solution proposed according to the invention makes it possible to create a heat conduction path essentially made of metallic materials, which on the one hand runs at an essentially constant distance from the housing or to the stator winding contained therein, so that robust and very reliable temperature measurement or temperature detection of the temperature of the stator winding of the electrical machine is possible. In the event of a temperature sensor defect, the stator or stator winding can continue to be used. The solution proposed according to the invention is also very cost-effective because the busbars to be used can be scaled, i.e. can be adapted to different sizes in a very simple manner. Since the solution proposed according to the invention does not require any connectors, their complex qualification can be dispensed with.

[0018] Furthermore, the device proposed according to the invention for detecting the temperature of the electrical machine can be overmolded using transfer molding. Sensitive components, such as twisted or twisted cables, which could be damaged by the high injection pressures encountered during transfer molding, are eliminated in the solution proposed according to the invention. Due to the fact that no voltage is applied to the passive conductor required for the connection or heat conduction to the at least one temperature sensor, complex insulation of individual temperature sensors to minimize the risk of short circuits can also be omitted.Since there is always a clear position of, for example, a carrier arrangement or a sleeve attachment from the connector rail, only a small temperature error occurs, which can be kept constant and can easily be taken into account when determining the measurement result.

[0019] Compared to previous solutions for measuring the temperature of electrical machines, the solution proposed by the invention is characterized by significantly lower assembly effort. Furthermore, compared to previous solutions, a significantly more cost-effective implementation of the device proposed by the invention for measuring the temperature of electrical machines is possible.

[0020] In this case, the costs for an additional, second temperature sensor can be saved because the algorithms required for temperature measurement are adapted in such a way that only one temperature sensor is sufficient to correctly detect the temperature on the stator of the electrical machine. Furthermore, the solution proposed according to the invention makes it possible to reduce component variance because identical current conductor components can be used for the passive conductor to the U, V, and W busbars, thus eliminating the need to maintain a separate component. Due to the principle of using identical parts, the solution proposed according to the invention can save considerable component and manufacturing costs without compromising the accuracy of the temperature measurement result. Short description of the drawings

[0021] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0022] They show: Fig. 1.1 the arrangement of two temperature sensors on the winding heads of the electrical machine, Fig. 1.2 the front view of the electrical machine according to Fig. 1.1 with a view of the connector rail, on the back of which the U, V, W busbars run, Fig. 2 a schematic representation of an embodiment of the device for temperature measurement proposed according to the invention and Fig. 3 an enlarged view of the heat conduction path established on the temperature measuring device proposed according to the invention. Embodiments of the invention

[0023] In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

[0024] According to the illustration Fig. 1.1 shows an electrical machine 10 in whose housing 12 a stator 22 with a number of winding heads 20 is embedded. From the rear view according to Fig. 1.1 shows that a U-shaped busbar 14, a V-shaped busbar 16 and a W-shaped busbar 18 extend from a connector rail 30, which is located at a 12 o'clock position with respect to the housing 12. The aforementioned busbars 14, 16, 18 extend essentially parallel to each other, starting from the connector rail 30 in the direction of the winding heads 20 of the stator 22. Furthermore, Fig. 1.1 shows that a first temperature sensor 24 and a second temperature sensor 26 are accommodated at a measuring location 34 within the stator 22. The first temperature sensor 24 and the second temperature sensor 26 are connected via a twisted-pair cable 28 to a plug contact 32 for at least one temperature sensor 24, 26 on the plug rail 30.

[0025] Fig. 1.2 shows the view of the electrical machine 10 from the front. Fig. 1.2 shows that individual connection sockets are located on the side of the plug-in rail 30 opposite the U-shaped busbar 14, the V-shaped busbar 16, and the W-shaped busbar 18. In addition to the sockets provided for the aforementioned busbars 14, 16, 18, the plug-in rail 30 has a plug contact 32 for the at least one temperature sensor 24, 26. As a rule, the housing 12 completely encloses the stator 22 or the winding overhangs 20 of the stator winding. The temperature of the electrical machine 10 in the region of the stator 22 is measured by means of a potting compound in which the at least one temperature sensor 24, 26, preferably both temperature sensors 24, 26, are embedded.

[0026] Fig. 2 shows an embodiment of the device proposed according to the invention for measuring the temperature of the electrical machine 10.

[0027] From the representation according to Fig. 2 shows that, in addition to active conductors 40, which are each connected to the U-busbar 14, the V-busbar 16, and the W-busbar 18, a further, namely a stress-free passive conductor 42 extends along the plug rail 30. Analogous to the active conductors 40, the passive conductor 42 includes a plug opening 44 at its end projecting into the housing 12. The passive conductor 42 used here represents a component identical to the U-, V-, and W-busbars (14, 16, 18), so that component variance can be reduced when implementing the solution proposed according to the invention.

[0028] From the representation according to Fig. 2 further shows that plug openings 44 are located on the rear part of the plug rail 30. The plug openings 44 represent ends of sleeve extensions 56, which extend from the rear of the plug rail 30 parallel to the housing 12 of the electrical machine 10. Contours in the form of a helix 60 can be seen on the outer surface of the sleeve extensions 56. The helix 60 on the outer surface has the function of compensating for tolerances between the busbars, in particular the U-, V-, and W-busbars 14, 16, 18, taking into account the respective required current-carrying capacity, and the stator 22 of the electrical machine 10. Furthermore, the helix 60 can be used to limit the force acting on the connected printed circuit board 70, so that excessive mechanical stress on the printed circuit board 70 can be avoided.

[0029] Fig. Figure 2 further shows that a support assembly 50 is located on the rear end face of the sleeve extension 56, which is formed in a sleeve length 58. The support assembly 50 is preferably designed as a copper sheet 46, which has good thermal conductivity. Instead of a material with very good thermal conductivity properties, such as copper, the support assembly 50 can also be made of other thermally conductive materials, such as aluminum.

[0030] The carrier arrangement 50 comprises a first leg 52 and a second leg 54. In the illustration according to Fig. 2, the two legs 52, 54 of the carrier assembly 50 are arranged substantially at right angles to one another and are overmolded with an overmolding 48 for thermal insulation. The overmolding 48, which serves as thermal insulation, is preferably made of a plastic material. The overmolding 48 extends at least over the carrier assembly 50 with the first leg 52 and second leg 54 and can optionally also enclose the sleeve extension 56, which in this case would also be provided with thermal insulation. On the inside of the first leg 52 of the carrier assembly 50, which extends parallel to the sleeve extension 56, there are preferably one temperature sensor 24 and a second temperature sensor 26 arranged next to one another. Due to the improvement of the measurement evaluation algorithms, a temperature sensor 24 can preferably be used in the course of the solution proposed according to the invention. Of course, as in Fig. 2, the possibility of using two temperature sensors (24, 26) arranged side by side is also provided. Cables extend from the two temperature sensors 24, 26, which are mounted here on the outside of the housing 12 on the first leg 52, to a PCB connector 68. This connector is connected to a printed circuit board (PCB) 70 at an interface 74.

[0031] From the representation according to Fig. 2 shows that, in this embodiment of the device for measuring the temperature of the electrical machine 10 proposed according to the invention, the two temperature sensors 24, 26 arranged on the first leg 52 are located outside the housing 12 of the electrical machine 10 and outside the winding heads 20 of the stator 22 or the stator winding. They are therefore very easily accessible. In the event of a failure, the two temperature sensors 24, 26 can be replaced without opening the housing 12 of the electrical machine 10 and without destroying or dismantling the stator 22 or the winding heads 20 accommodated therein, and can be reconnected to the printed circuit board 70 in the form of a PCB using the PCB connector 68. This ensures very good accessibility and maintenance.

[0032] Fig. 3 shows an enlarged view of the components of the device for detecting the temperature of the electrical machine 10.

[0033] From the representation according to Fig. 3 shows that the passive conductor 42, ie the stress-free conductor, is formed in a length 62 extending in the vertical direction. The plug opening 44 is located at the lower end of the passive conductor 42. The passive conductor 42, preferably made of a metallic material, is preferably formed integrally with the sleeve extension 56. The sleeve extension 56 is connected to the passive conductor 42 by its first end face 64 and receives the carrier arrangement 50, in particular its second leg 54, on its second end face 66. From the illustration according to Fig. 3 shows that the two adjacent temperature sensors 24, 26 are located on one side of the first leg 52, which thus have very good accessibility. Fig. The temperature sensors 24, 26 shown in Figure 3 can be connected via schematically indicated cables to the interface 74 of the circuit board 70 in the form of the PCB connector 68. In the case of replacing defective temperature sensors 24, 26, replacement and reconnection as well as electrical contact with the circuit board 70 can thus be achieved very easily. Fig. 3 it can also be seen that the sleeve extension 56 is formed between the first end face 64 and the second end face 66 in a sleeve length 58. From Fig. 3 further shows that a thermal conduction path 76 extends from the passive conductor 42 through the material of the sleeve extension 56, merging into the second leg 54 of the support assembly 50. The thermal conduction path 76 ends at the two temperature sensors 24, 26, which extend on the externally accessible side of the first leg 52 of the support assembly 50, which is made of a thermally conductive material, such as a copper sheet 46.

[0034] Because the connector rail 30, as shown in Fig. 2, is located very close to the winding overhang 20 of the stator 22 or the stator winding of the electrical machine 10, and because the distance is always almost the same, there is a small and constant temperature deviation with respect to the temperature in the stator 22 of the electrical machine 10. Furthermore, the heat conduction path 76 is essentially completely enclosed by the overmolding 48 made of a plastic material and is therefore well thermally insulated. Because of the essentially constant distance to the winding overhang 20 of the stator 22, the measurement uncertainty is significantly reduced, i.e. the measured result of the temperature measurement is much more meaningful. The arrangement of the temperature sensors 24, 26 on the carrier arrangement 50 significantly improves their accessibility in the event of a failure of one or both temperature sensors 24, 26, such that replacement can be achieved without destroying or dismantling the stator 22 or the housing 12 of the electrical machine 10.The solution proposed according to the invention according to the . Fig. 2 and Fig. 3 thus represents a very robust design variant of a device for measuring the temperature of an electrical machine 10. In the event of failure of one or both temperature sensors 24, 26, disposal of the complete stator 22 can be avoided. Due to the use of the connector rail 30 according to the Fig. 2 and Fig.3, favorable scaling can be achieved, which also applies to the busbars used in the form of U, V and W busbars 14, 16, 18. Since the solution proposed according to the invention eliminates the use of twisted or paired cables, which are susceptible to injection molding, i.e., overmolding with high injection pressures, the device proposed according to the invention for temperature measurement can be treated by injection molding. Since no voltage is applied to the passive conductor 42, the otherwise required, complex insulation of the at least one temperature sensor 24, 26 is also omitted, with one temperature sensor 24 preferably being used. Due to the clear position of the device proposed according to the invention, a relatively low measurement inaccuracy, i.e., a low temperature error, results, as explained above.

[0035] The device proposed according to the invention for detecting the temperature of the electrical machine 10 is, moreover, a very cost-effective device and is further characterized by very low assembly effort; in particular, it provides a very simple repair option in the event of defective temperature sensors 24, 26.

[0036] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible within the scope of the claims, which are within the scope of one skilled in the art.

Claims

[1] Device for measuring the temperature of an electrical machine (10), the stator (22) of which is enclosed by a housing (12), and the stator (22) is electrically contacted by means of U-, V-, W-busbars (14, 16, 18) which are accommodated on a plug rail (30), and the temperature of the electrical machine (10) is detected by at least one temperature sensor (24, 26), characterized by that the at least one temperature sensor (24, 26) is thermally conductively connected to a stress-free, passive conductor (42) which contains a metallic material and is accommodated on the plug rail (30). [2] Device according to claim 1, characterized by that the passive conductor (42) comprises a sleeve extension (56) which is part of a heat conduction path (76). [3] Device according to claims 1 and 2, characterized bythat a support arrangement (50) is fastened to the sleeve extension (56), which is made of a heat-conducting material (46), in particular as a copper sheet or as an aluminum component. [4] Device according to claims 1 to 3, characterized by that the support arrangement (50) comprises a first leg (52) and a second leg (54) which are arranged substantially at right angles to one another. [5] Device according to claims 1 to 4, characterized by that the carrier arrangement (50) preferably has a temperature sensor (24). [6] Device according to claims 1 to 5, characterized by that at least the carrier arrangement (50) with the temperature sensor (24) accommodated thereon is provided with an overmolding (48) serving as thermal insulation, in particular made of a plastic material. [7] Device according to claims 1 to 6, characterized bythat the sleeve extension (56) is provided with a helix (60) along its outer surface. [8] Device according to claims 1 to 7, characterized by that the preferably one temperature sensor (24) is connected to an interface (74) of a printed circuit board (70) (PCB, Printed Circuit Board). [9] Device according to claims 1 to 8, characterized by that the plug rail (30), to which the passive conductor (42) is thermally connected, is designed as a common part to the U, V, W busbars (14, 16, 18). [10] Device according to claims 1 to 9, characterized by that the preferably one temperature sensor (24) is arranged outside the housing (12) and outside the stator (22). [11] Use of the device according to one of claims 1 to 10 for detecting the temperature of an electrical machine (10), in particular in the region of the stator (22) of the electrical machine (10)

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