Arrangement for temperature measurement of a stator winding of an electric machine

Abstract

Arrangement for temperature detection of a stator winding of an electrical machine (36) with - a temperature sensor (10) which forms an essentially one-dimensional configuration and which has a sensor head (12) with connecting conductors (16a, b) at its end, wherein - a free-standing section of the temperature sensor (10) projects axially into the electric machine (36) through an end-face housing opening (48) and engages in an intermediate space (43) formed in the circumferential direction between two coils (42) of the stator winding and is in heat transfer contact with the stator winding, characterized in that an axial sensor guide element (50) is arranged in the area of ​​the end-face housing opening (48), by which the temperature sensor (10) is guided on at least a part of an insertion path when being inserted into the intermediate space (43) and is held in its installation position.

Description

[0001] The invention relates to an arrangement for temperature detection of a stator winding of an electrical machine according to the preamble of the independent claim, as is known, for example, from DE 10 2010 030 968 B4.

[0002] JP 2003092858 A describes a mounting structure for a motor winding temperature sensor, enabling simple and automated mounting while ensuring stable temperature measurement accuracy. A temperature sensor, secured by a guide, is inserted and fixed in a tunnel-like gap between the stator core of a motor and the coil end of a winding. A space for the temperature sensor is located in the coil end of a winding drum.

[0003] German patent DE 102010063581 A1 relates to a known stator that uses electrical coils and a temperature sensor for measuring the coil temperature. The temperature sensor is located between two coils on a sensor carrier and comprises a sensor element and a sensor cable connected to the sensor element. The sensor carrier has a spring element that presses the sensor element against one of the coils.

[0004] EP 1278291 A2 describes a sensor carrier made of elastically deformable material, attached to a holder that covers a stator winding. A sensor for heat protection of the stator winding is also attached to one end of the sensor carrier. The holder, the sensor carrier, and the sensor form a single unit. When the holder is attached to the stator, the sensor carrier contracts under the force exerted by the pressure of the sensor on the stator winding. This elastic expansion force of the sensor carrier presses the sensor against the stator winding.

[0005] JP 2004297958 A describes a structure for mounting a temperature sensor for an electric motor, which simplifies sensor replacement while simultaneously enabling accurate coil temperature measurement. The temperature of a stator coil can be accurately measured with a temperature sensor because the temperature of the stator coil, mounted in a slot of the stator in an electric motor, is transferred to the sensor via a temperature transfer pin. The surrounding part of the sensor, which comes into contact with air, is covered by an insulating element, preventing any temperature drop.If a fault occurs in the sensor, the sensor is removed from a mounting hole, a new temperature sensor is simply pushed through the mounting hole, and an axial part of one end of the sensor is simply inserted into a mounting hole of the temperature transfer stud, meaning that only the temperature sensor can be replaced.

[0006] JP 2011223827 A deals with an accurate measurement of coil temperature by mounting a temperature sensor relatively simply in a rotating armature shaft. The rotating armature shaft contains an annular stator core; a plurality of slots formed in the stator core; a plurality of distributed winding coil sections inserted sequentially into the plurality of slots according to a predetermined arrangement along a circumferential direction of the stator core; a plurality of transition conductor sections extending adjoining each other in a diameter direction of the stator core within a portion of the distributed winding coil sections; a temperature sensor holder mounted on one of the transition conductor sections; and a temperature sensor held by the temperature sensor holder.

[0007] US 2012 / 0 111 145 A1 deals with an electric motor and a vehicle propulsion device with the same. The electric motor comprises a core assembly with multiple core assemblies attached to a housing, an annular busbar attached to the core assembly, several support elements each attached to the multiple core assemblies, a mounting element that holds a first sensor and is attached to a portion of a terminal receptacle such that the first sensor is immersed in oil contained within the housing, and a mounting element that holds a second sensor and is attached to a portion of a terminal receptacle such that the second sensor is positioned to measure a temperature of the coils between adjacent terminal receptacles not immersed in the oil.

[0008] EP 1221601 A1 describes the manufacture of an electrical component consisting of a sensor element connected to metallic terminals via metallic conductors. The process reduces the number of manufacturing steps. It involves inserting a prefabricated assembly, comprising the sensor element, the conductors, and the terminals, into a plastic mold. The sensor element is brought into contact with position-fixing supports within the mold. Molten metal is then poured into the mold so that, at least initially during the filling process, it comes into contact with a specific surface area of ​​the sensor element. This forces the sensor element to adhere firmly to the supports during the filling process, holding it in a predetermined position within the mold.After the melt has solidified, the molded part with the embedded sensor element and conductor paths is removed from the mold.

[0009] The invention is based on the problem of mounting a temperature sensor for detecting a stator winding temperature of an electric machine blindly, i.e. with the machine housing closed, from the outside at a desired position on the stator winding located inside the machine.

[0010] During the installation of a temperature sensor, manufacturing tolerances may cause the radial and / or circumferential position of the axially oriented sensor housing opening to deviate from that of a predetermined mounting location for the sensor head. The temperature sensor itself is flexible, which can be advantageous for allowing a degree of self-adjustment, but this flexibility has the disadvantage that, when axially inserted into the machine interior, it can migrate circumferentially or radially in an unpredictable manner, preventing the sensor head from being positioned correctly on the stator winding. Furthermore, applying disproportionately high installation forces also poses a risk of damaging the sensor head. This is particularly significant if the sensor head is to be positioned at a defined location within a wedge-shaped gap between the coils, where it is intended to contact at least one of them.

[0011] Starting from the aforementioned problem, the invention aims to improve a generic arrangement for detecting a winding temperature of an electric machine in such a way that a temperature sensor, which is to be mounted blindly from the outside of the machine, comes into a defined position on the stator winding.

[0012] The aforementioned problem is solved by means of an arrangement according to the features of the independent patent claim.

[0013] According to the invention, an arrangement for temperature detection of a stator winding of an electric machine is provided, comprising a temperature sensor that forms a substantially one-dimensional configuration and has a sensor head with connecting conductors at its end. A cantilevered section of the temperature sensor projects through a housing opening into the electric machine and engages in a space formed between two coils of the stator winding, thus being in heat transfer contact with the stator winding. This arrangement is characterized by the fact that a sensor guide element is arranged in the region of the housing opening, by which the temperature sensor is guided along at least a portion of an insertion path when being inserted into the space and held in its installed position.

[0014] The proposed arrangement largely prevents the temperature sensor from migrating from the outside of the machine during assembly and allows for reproducible adjustment of the sensor's intended position. As a result, the control of the electric machine can be improved based on the temperature readings generated by the sensor. The sensor guide element can, for example, have a tubular or plate-like shape and is preferably made of plastic. Before inserting the temperature sensor, the guide element can be easily inserted from the outside of the machine housing into the designated opening and, if necessary, secured there.

[0015] The independent claims specify advantageous embodiments and further developments of the invention.

[0016] To further simplify assembly, the sensor guide element can be provided with a guide channel that tapers in the insertion direction of the temperature sensor. Specifically, the guide channel can taper radially in the axial direction of the electrical machine. Furthermore, the guide channel can also taper circumferentially in the axial direction of the electrical machine. Both measures allow for a comparatively large insertion opening for easy insertion of the sensor, with the narrowing of the guide channel only occurring with the further axial extension of the sensor guide element. For this purpose, the sensor guide element can, for example, be essentially funnel-shaped.

[0017] With particular advantage, the sensor guide element extends into the coil space, and can be positioned directly at the point where the sensor head is placed on the winding.

[0018] In connection with the extension of the sensor guide element into the coil space, it can have a lateral clearance relative to the housing opening, which allows the guide element to self-adjust during insertion by utilizing this clearance and thus compensating for any positional deviation of the housing opening relative to a coil space.

[0019] According to a further advantageous embodiment, the temperature sensor has a conductor alignment element which, with respect to the axial extent of the conductors of the sensor head, is designed to rotate them in the lateral plane, and wherein the conductors are radially aligned with respect to the electrical machine in the space between them. This means that the spatial position of a temperature sensor with a non-circular cross-section, e.g., an elliptical shape, can be precisely set.

[0020] With a further advantage, the temperature sensor and the guide element can be fixed together to the housing opening of the electric machine using a fixing element.

[0021] The invention is explained below by way of example with reference to the accompanying figures.

[0022] They show: Fig. 1 a pre-assembled temperature sensor; Fig. 2 a representation of the cantilevered sensor section in a cross-section; Fig. 3 a connecting conductor alignment element in different positions; Fig. 4 an arrangement of a sensor on a carrier; Fig. 5a, b a representation of an electric machine with a temperature sensor arranged between two stator coils; Fig. 6 an arrangement for temperature detection of a stator winding with a sensor guide element; Fig. 7 a representation of a sensor guide element.

[0023] In Fig. Figure 1 shows a pre-assembled temperature sensor 10 comprising a sensor head 12 with two terminals 12a, b, each connected by means of a crimp connection to two terminals 14a, b offset from each other in the direction of extension, with insulated connecting conductors 16a, b. The temperature sensor 10 is designed here as an NTC or PTC resistance element, which, however, is irrelevant for the following explanations. The temperature sensor 10 further comprises an outer protective sleeve, in particular a plastic sleeve 18, for example in the form of heat-shrink tubing, which completely surrounds the sensor head 12 and the connecting conductors 16a, b at least over part of their length, with the end section of the plastic sleeve 18 on the sensor head side being closed. It can be seen that the sensor 10 is approximately rod-shaped and essentially one-dimensional, and as shown in Figure 1. Fig. 2 can be seen, in a lateral plane having an outer cross-section that deviates from a circular cross-section and is non-uniform in the radial direction, approximately elliptical.

[0024] Reference numeral 20 designates a conductor alignment element into which the two conductors 16a, b are inserted and secured, so that a tensile load acting on the free terminals of the conductors 16a, b cannot act on the connection points 14a, b, thus relieving strain on them. In addition to strain relief, the conductor alignment element 20 also changes the position of the two conductors 16a, b. These enter the conductor alignment element 20 from a connection point (not shown) with a predetermined spatial entry position and, within the conductor alignment element 20, more precisely by means of a guide structure incorporated therein, undergo a change in position towards an exit position defined relative to the entry position. In this exit position, the conductors 16a, b emerge from the conductor alignment element 20 in the direction of the sensor head 12.

[0025] This is particularly good in Fig. The connecting conductor alignment element 20, shown in two different perspective views, is designed here as an elastic injection-molded plastic part with two legs 22, 24 positioned at an angle to each other. However, the angular design of the connecting conductor alignment element is by no means mandatory; rather, it can be freely adapted to the conditions present at an installation site. In this case, leg 22 forms a trough-shaped inlet structure into the base of which the connecting conductors 16a, b can be placed side by side, coming from a connection point. The leg 24, projecting at an angle, specifically at a right angle, is tubular on the outside and forms an outlet structure.In one of the legs 22, 24 or between the legs 22, 24, a region 26, here designed as a disc-shaped wall, is provided with two through-openings 26a, b, which, with respect to an axial extension of the connecting conductors 16a, b, causes their rotation in a lateral plane. It is in . Fig. 3. It is evident that at the free end of the initial structure or leg 24, a recess or receiving section 28 is provided, adapted to the outer cross-section of the shell 18 or this cross-section, and here approximately elliptical, which encloses the open end section of the plastic shell 18 and fixes it both radially and at least axially in one direction. The protective shell 18 can also be fixed axially on both sides by gluing or by a mutual snap-fit ​​or clamping connection. This design allows the sensor head 12 to be held cantilevered on the connecting conductor alignment element 20 by means of the shell 18.

[0026] The arrangement between the input and output structures 22, 24 is designed such that the inner guide structure within the connecting conductor alignment element 20, with respect to an axial extension of the connecting conductors 16a, b, takes into account a minimum permissible bending radius R. min . is angled, as this one in Fig. 1 can be seen.

[0027] For the defined positioning of the temperature sensor 10 on a device or on a support element 32, the connecting conductor alignment element 20 is adjusted with regard to Fig. 4 A holding area is provided, which in the present example includes an annular groove 30 on the tubular leg 24. A corresponding holding section 34 or counter-locking section of the support element 32 can engage in this annular groove 30, which here forms part of a snap-fit ​​connection, and secure the sensor 10 in its main direction of extension as well as laterally. For this purpose, the holding area of ​​the support element 32 has a design feature that is unique with respect to its arrangement within a lateral plane, so that the temperature sensor 10 with its tubular leg 24 can only be arranged in a rotational position predetermined relative to the support element 32. In this way, the temperature sensor 10 can be spatially oriented and uniquely fixed to a support element.

[0028] The Fig. Figures 5a and 5b show an arrangement for detecting the temperature of an electric machine 36 with a temperature sensor 10 as described above, wherein its connecting conductor alignment element 20 is fixed to or relative to a stator 38 of the electric machine 36 by means of a previously described support element 32 and a stator support ring 40. The cantilevered section of the temperature sensor 10 is defined and aligned with respect to its axial extent in a lateral plane relative to a stator winding. In particular, the stator winding comprises individual coils 42 arranged regularly around the circumference of the overall circular stator 38, which are arranged on stator teeth provided on a stator yoke 44, and wherein a space 43 is formed in the circumferential direction between each pair of coils 42.In the present case, a section of an electric machine 36 is shown, with a rotor 46 arranged inside the stator 38 and rotatably mounted about an axis A. The space 43 between two coils 42 is wedge-shaped and tapers radially inwards. It can be seen that the cantilevered section of the temperature sensor 10 projects axially into such a space 43 with respect to the electric machine 36, the shorter lateral dimension of the cantilevered sensor section being oriented circumferentially and the longer lateral dimension being oriented radially with respect to the electric machine 36, and the sensor head being in contact with one or both adjacent coils 42 via the protective casing 18 for thermal and heat transfer purposes.

[0029] Fig. Figure 6 shows a further arrangement for temperature measurement of a stator winding of an electric machine 36 with a temperature sensor 10 described above, which again forms an essentially one-dimensional configuration and has at its end a sensor head 12 located in a protective casing 18 with connecting conductors 16a, b. The cantilevered section of the temperature sensor 10 projects axially into the electric machine 36 through an end-face opening 48 of the housing 41 by means of an angled connecting conductor alignment element 20 described above and engages in a space 43 formed between two coils 42 of the stator winding. The sensor head 12 is located there with the stator winding, i.e., with one or both coils 42, in heat transfer contact.The connecting conductor alignment element 20, made here from an elastomer material, is also designed here with respect to an axial extension of the connecting conductors 16a, b of the sensor head 12 to rotate them in the lateral plane, wherein the connecting conductors 16a, b are aligned radially with respect to the electrical machine 36 in the wedge-shaped gap 43, as already shown in . Fig. 5b is shown.

[0030] It is in Fig. Figure 6 shows that a sensor guide element 50 with a guide channel 52 is arranged in the area of ​​the housing opening 48, through which the temperature sensor 10 is guided along at least part of an insertion path when inserted into the coil space 43 and held in its installation position. In the illustrated embodiment, the sensor guide element 50 extends axially into the space 43.

[0031] Fig.Figure 7 shows a sensor guide element 50 made of plastic, which is at least partially open and essentially funnel- or spout-shaped. Its guide channel 52 tapers radially and circumferentially in the axial direction of the electric machine 36. This design allows the temperature sensor 10 to assume a desired radial position relative to the stator coils 42. The circumferential narrowing of the guide channel 52 enables the temperature sensor 10 to be firmly seated against the winding. The sensor 10 is supported by an adjacent wall region 54 of the sensor guide element 50, which is wedge-shaped in the insertion direction of the sensor 10 and, for example, has an increasing wall thickness. For axial support, an annular collar 56 is provided on the sensor guide element 50, which rests on and is supported by the outside of the housing 41.A recess 58 is provided on the ring collar 56 for receiving the connecting conductor alignment element 20, wherein the connecting conductor alignment element 20 does not rise axially above spacer ribs 60 that act as compression ribs. The maximum outer diameter or the maximum width of the section extending through the machine housing 41 is selected to be slightly less than the clear width of the housing opening 48, so that the sensor guide element 50 can adjust itself, at least in the circumferential direction, by utilizing the resulting lateral play with respect to the housing opening 48 and can be inserted into a coil space 43 essentially without stress.

[0032] The temperature sensor 10 and the guide element 50 are fixed together by means of a retaining element 62, in this case a retaining plate, which is axially pressed against the crimp ribs 60 and thereby presses the ring collar 56 of the sensor guide element 50 against the housing 41 and simultaneously deforms the elastic connecting conductor alignment element 20 so that it lies close to the inner surface of the guide element 50 and an edge area of ​​the housing opening 48. Reference symbol list 10 Temperature sensor 12 Sensor head 12a, b connection 14a, b junction 16a, b Connection conductor 18 Protective case 20 connection conductor alignment element 22, 24 thighs 26 wall area 26a, b Opening 28 Recording section 30 Ring groove 32 Support element 34 Stop section 36 electric machine 38 Stator 40 carrying rings 41 cases 42 coil 43 spaces 44 Stator yoke 46 Rotor 48 Housing opening 50 Sensor guide element 52 Guide channel 54 Wall area 56 Ring collar 58 recess 60 Distance bridge 62 retaining element A rotor axis R min Bending radius

Claims

[1] Arrangement for temperature detection of a stator winding of an electric machine (36) with - a temperature sensor (10) which forms an essentially one-dimensional configuration and which has a sensor head (12) with connecting conductors (16a, b) at its end, wherein - a free-standing section of the temperature sensor (10) projects axially into the electric machine (36) through an end-face housing opening (48) and engages in a space (43) formed in the circumferential direction between two coils (42) of the stator winding and is in heat transfer contact with the stator winding, characterized by , that in the area of ​​the frontal housing opening (48) an axial sensor guide element (50) is arranged, through which the temperature sensor (10) is guided on at least part of an insertion path when being inserted into the space (43) and is held in its installation position. [2] Arrangement according to claim 1, characterized by, that the sensor guide element (50) has a guide channel (52) which is tapered in an insertion direction of the temperature sensor (10). [3] Arrangement according to claim 1 or 2, characterized by , that the guide channel (52) is radially tapered in the axial direction of the electrical machine (36). [4] Arrangement according to one of claims 1-3, characterized by , that the guide channel (52) is designed to taper in the circumferential direction in the axial direction of the electrical machine (36). [5] Arrangement according to one of claims 1-4, characterized by , that the sensor guide element (50) extends axially into the space (43). [6] Arrangement according to one of claims 1-5, characterized by , that the sensor guide element (50) can be inserted into the space (43) in a self-adjusting manner by utilizing a lateral play to the housing opening (48). [7] Arrangement according to one of claims 1-6, characterized by, that the temperature sensor (10) has a connecting conductor alignment element (20) which is designed to rotate the connecting conductors (16a, b) of the sensor head (12) in the lateral plane with respect to an axial extension and wherein the connecting conductors (16a, b) are aligned radially in the space (43) with respect to the electrical machine (36). [8] Arrangement according to one of claims 1-7, characterized by , that the temperature sensor (10) and the guide element (50) are jointly fixed to the housing opening (48) of the electric machine (36).

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