Rotating electric machine stator

Abstract

To provide a rotary electric machine stator that can properly detect the temperature of a stator winding.SOLUTION: The rotary electric machine stator includes a stator core 11, a stator winding 12 provided on the stator core, a neutral busbar 14 connected to a coil end portion of the stator winding, and a resin sealed portion 61 in which the coil end portion and the neutral line busbar are sealed with an insulating resin in a range including an axial tip portion of the coil end portion and the neutral busbar. A temperature sensor is provided integrally in the neutral line busbar, and the resin sealed portion has bubbles B in the vicinity of the neutral line busbar.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The disclosure of this specification relates to a stator for a rotating electric machine. [Background technology]

[0002] In a known configuration of a stator of a rotating electric machine, a neutral bus bar is connected to a coil end portion of a stator winding, and a temperature sensor is provided on the neutral bus bar. Also known is a configuration in which the coil end portion of the stator winding and the neutral bus bar are sealed with insulating resin (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-121491 Summary of the Invention [Problem to be solved by the invention]

[0004] Because the currents of each phase concentrate in the neutral bus bar, providing a temperature sensor in the neutral bus bar makes it possible to detect the temperature of the stator appropriately. However, in a configuration in which the neutral bus bar is sealed with resin, there is a concern that if heat from the neutral bus bar is released through the insulating resin, the temperature detected by the temperature sensor may be lower than the actual temperature.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a stator for a rotating electrical machine that can properly detect the temperature of the stator windings. [Means for solving the problem]

[0006] Method 1 is: a stator core; a stator winding provided on the stator core; a neutral bus bar connected to a coil end portion of the stator winding; a resin sealing portion in which the coil end portion and the neutral bus bar are sealed with insulating resin in a range including the axial tip end portion of the coil end portion and the neutral bus bar; A stator for a rotating electric machine comprising: a temperature sensor is integrally provided on the neutral bus bar, The resin sealing portion has air bubbles around the neutral bus bar.

[0007] The resin sealing portion has air bubbles around the neutral bus bar, which increases the thermal resistance of the insulating resin around the neutral bus bar and suppresses heat dissipation from the neutral bus bar through the insulating resin. This suppresses temperature drops in the neutral bus bar and allows the temperature sensor integrated into the neutral bus bar to properly detect the stator temperature.

[0008] In a second aspect, the resin sealing portion has air bubbles between the plate surface of the neutral bus bar and the outer surface of the resin sealing portion.

[0009] Heat from the neutral bus bar is more likely to be released from the plate surface, which has a larger surface area than the other outer surfaces of the bus bar. In this regard, by providing air bubbles between the plate surface of the neutral bus bar and the outer surface of the resin sealing portion, heat release from the plate surface of the neutral bus bar can be suppressed.

[0010] In the third aspect, air bubbles are present in the resin sealing portion in a state where they are in contact with the surface of the neutral bus bar.

[0011] The insulating resin of the resin sealing portion and the neutral bus bar have different linear expansion coefficients, and it is thought that cracks will occur in the insulating resin due to distortion caused by temperature changes. Furthermore, it is thought that cracks caused by distortion are likely to occur at the interface between the insulating resin and the neutral bus bar. There is a concern that refrigerant entering the cracks will promote heat dissipation from the neutral bus bar, causing a drop in the temperature of the neutral bus bar.

[0012] In this regard, the resin sealing portion is configured so that air bubbles are in contact with the surface of the neutral bus bar. This prevents cracks caused by distortion due to thermal stress and reduces heat dissipation from the neutral bus bar. This prevents a temperature drop in the neutral bus bar and allows for accurate detection of the stator temperature.

[0013] In the fourth measure, air bubbles are present in the resin sealing portion near the corners of the neutral bus bar.

[0014] The resin-sealed portion surrounding the corner of the neutral bus bar forms an inside corner, and it is thought that stress concentration due to expansion and contraction of the insulating resin caused by temperature changes could lead to cracks. In this regard, the resin-sealed portion is configured so that air bubbles are present near the corner of the neutral bus bar, which reduces the stress generated near the corner of the neutral bus bar and prevents cracks from occurring due to stress. This prevents the temperature drop of the neutral bus bar and allows for accurate detection of the stator temperature.

[0015] In the fifth aspect, the resin-sealed portion has a void region in which more voids exist around the neutral bus bar than around the stator winding.

[0016] In the resin sealing portion, the area around the neutral bus bar is made into a bubble region where there are more bubbles than around the stator winding. In other words, there are fewer bubbles around the stator winding than around the neutral bus bar. This prevents problems such as a reduction in insulation between the phase windings of each phase due to the presence of bubbles. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. [Figure 2] Front view of the stator. [Figure 3] FIG. [Figure 4] FIG. 4 is a perspective view showing a conductor segment and a part of a stator core. [Figure 5]FIG. 10 illustrates some conductor segments received within slots. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. 10 is a diagram showing the location of air bubbles present around the neutral bus bar. [Figure 10] 5A and 5B are diagrams illustrating molding of a resin sealing portion in a coil end portion. [Figure 11] FIG. 2 is a diagram showing the configuration of a neutral bus bar. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of a rotating electric machine according to the present invention will be described with reference to the drawings. In the following embodiments and modifications, identical or equivalent parts are designated by the same reference numerals in the drawings, and the same explanations are incorporated herein. A motor as a rotating electric machine according to this embodiment is used, for example, as an electric motor for a vehicle or an aircraft.

[0019] The rotating electric machine of this embodiment is applicable to permanent magnet synchronous motors, wound field motors, and induction motors, and is a rotating electric machine with three-phase windings. The rotating electric machine includes a cylindrical stator 10 shown in FIG. 1 and a rotor (not shown) disposed radially inside the stator 10. The rotor is disposed relative to the stator 10 so as to be rotatable about a rotation axis. Hereinafter, the term "axial direction" refers to the axial direction of the stator 10, i.e., the axial direction of the rotor's rotation axis; the term "radial direction" refers to the radial direction of the stator 10, i.e., the direction passing through the center of the rotor's rotation axis and perpendicular to the rotation axis; and the term "circumferential direction" refers to the circumferential direction of the stator 10, i.e., the direction around the rotor's rotation axis.

[0020] As shown in Figures 1 and 2, the stator 10 includes a stator core 11 having an annular shape and a stator winding 12 wound around the stator core 11. The rotating electric machine of this embodiment is an inner rotor type rotating electric machine, and the rotor is rotatably disposed radially inside the stator 10. The stator winding 12 is a three-phase winding having a U-phase winding, a V-phase winding, and a W-phase winding as phase windings for each phase. A power bus bar 13 is connected to one end of each phase winding, and a neutral bus bar 14 is connected to the other end. In the stator winding 12, the area that overlaps with the stator core 11 in the axial direction is an in-slot coil portion CS, and the portions on both axial sides that are axially outward of the stator core 11 are coil end portions CE1, CE2.

[0021] 3, the stator core 11 has an annular back yoke 21 and a plurality of teeth 22 that protrude radially inward from the back yoke 21 and are arranged at predetermined distances in the circumferential direction, with slots 23 formed between adjacent teeth 22. The slots 23 have an opening shape that extends longitudinally in the radial direction and are provided at equal intervals in the circumferential direction in the stator core 11. The stator windings 12 are provided in a state of being wound around the slots 23. The stator core 11 is configured as a core sheet laminate in which core sheets made of, for example, electromagnetic steel sheets, which are magnetic materials, are stacked in the axial direction.

[0022] The stator winding 12 is configured by connecting three-phase windings in a Y-connection (star-connection). The stator winding 12 generates magnetic flux when power (AC power) is supplied from a power source via an inverter (not shown). The stator winding 12 is configured using a plurality of conductor segments 30 as divided conductors, each of which is an electrical conductor of a uniform thickness and a substantially rectangular cross section (flat cross section) formed into a substantially U-shape. The segment structure of the stator winding 12 will be described in detail below.

[0023] Fig. 4 is a perspective view showing a conductor segment 30 and a portion of the stator core 11. As shown in Fig. 4, the conductor segment 30 is generally U-shaped and has a pair of linear straight portions 31 and a turn portion 32 that is bent so as to connect the pair of linear portions 31. The pair of linear portions 31 have a length that is longer than the axial thickness of the stator core 11. The conductor segment 30 is made using a flat conductor wire in which a conductor having a rectangular cross section (a conductor having a pair of opposing flat portions) is covered with an insulating coating, and the tip of each linear portion 31 has the insulating coating removed to form an exposed conductor portion 33 where the conductor is exposed.

[0024] A plurality of conductor segments 30 are inserted into the slots 23 of the stator core 11 in a radially aligned state. In this embodiment, the slots 23 are configured to accommodate the straight portions 31 of the conductor segments 30 in a stacked state in four layers. In the conductor segment 30, a pair of straight portions 31 are accommodated in each of two slots 23 separated by a predetermined coil pitch. The portion of the straight portions 31 accommodated in the slots 23 corresponds to the in-slot coil portion CS of the stator winding 12. An insulating sheet 24 is provided in the slots 23 to provide electrical insulation between the stator core 11 and the stator winding 12 (conductor segments 30). The insulating sheet 24 is folded to surround the plurality of conductor segments 30 inserted into the slots 23, and is sandwiched between the inner circumferential surface (inner wall surface) of the stator core 11 and the conductor segments 30 within the slots 23.

[0025] A pair of straight portions 31 of the conductor segment 30 are accommodated in the two slots 23, each shifted by one radial position. For example, when one straight portion 31 is accommodated in the nth position from the radially innermost side (back yoke side), the other straight portion 31 is accommodated in the (n+1)th position from the radially innermost side.

[0026] When each conductor segment 30 is inserted into a slot 23 of the stator core 11, the straight portion 31 of each conductor segment 30 is inserted first from the first end of the stator core 11, with the tip of the straight portion 31 protruding from the second end. In this case, at the first end of the stator core 11, one coil end portion CE1 is formed by the turn portion 32 of the conductor segment 30. At the second end of the stator core 11, the non-turn side of each straight portion 31 is bent in the circumferential direction, and the straight portions 31 of different conductor segments 30 are connected to each other to form the other coil end portion CE2. An overview of each coil end portion CE1, CE2 is shown in FIG. 2. Next, the connection of the conductor segments 30 at the coil end portion CE2 will be described in more detail. First, the connection between the conductor segments 30 will be described.

[0027] Fig. 5 is a diagram showing some of the conductor segments 30 housed in the slots 23. In Fig. 5, the stator core 11 is shown by imaginary lines. In the conductor segments 30, the opposite sides of the turn portions of a pair of straight portions 31 protrude from the axial end face (the upper end face in the figure) of the stator core 11 and are bent in the circumferential direction so as to be oblique at a predetermined angle relative to the core end face. The exposed conductor portions 33 at the tips of different conductor segments 30 are joined together by welding, thereby connecting multiple conductor segments 30.

[0028] At the coil end portion CE2, the circumferential tip end of one conductor segment 30 extending in a fixed circumferential direction on the axial outside of the stator core 11 is joined to the circumferential tip end of another conductor segment 30 extending in the opposite direction to the fixed circumferential direction. As a result, at the coil end portion CE2 of the stator winding 12, the straight portions 31 of the conductor segments 30 extend in a direction inclined with respect to the axial direction and are folded back at a predetermined apex position. The conductor segments 30 include those in which the anti-turn portion side of each straight portion 31 is bent circumferentially to the same side as the turn portions 32, and those in which the anti-turn portion side of each straight portion 31 is bent circumferentially to the opposite side to the turn portions 32.

[0029] In the phase winding of each phase, the conductors are connected at their intermediate portions by joining the conductor segments 30 together, while at the winding ends, the power line busbar 13 and neutral line busbar 14 of each phase are connected to the conductor exposed portion 33. Here, the configuration of the neutral line busbar 14 in particular will be described in detail.

[0030] 6(a) and (b) are perspective views of the neutral bus bar 14. Fig. 6(a) shows only the neutral bus bar 14, and Fig. 6(b) shows the neutral bus bar 14 with a temperature sensor 51 attached thereto.

[0031] The neutral bus bar 14 is made of a rectangular conductor and has a long, plate-shaped main body 41 and multiple connection portions 42 protruding from the main body 41. The main body 41 is formed long and extends in an arc shape in a plan view. When assembled to the stator winding 12, the neutral bus bar 14 has the main body 41 extending in the circumferential direction and the connection portions 42 extending radially inward from the main body 41. The radial tip portions of the connection portions 42 are joined to the winding ends of the respective phase windings at the coil end portion CE2.

[0032] The main body 41 is folded back in the thickness direction at the midpoint in the longitudinal direction, and a temperature sensor 51 that detects the temperature of the stator 10 is attached and sandwiched between the folded main body 41. The temperature sensor 51 is configured as a temperature sensor module that includes a thermistor element and a circuit section.

[0033] 7, a resin sealing portion 61 is provided at one axial end of the stator 10, where the coil end portion CE2 is sealed with insulating resin. The resin sealing portion 61 is formed in an annular shape so as to cover the welded portions of each conductor segment 30 and the neutral bus bar 14. The temperature sensor 51 attached to the neutral bus bar 14 is also covered by the resin sealing portion 61.

[0034] The resin sealing portion 61 is provided over a partial range of the coil end portion CE2 in the axial direction. Specifically, the axial range of the resin sealing portion 61 includes the welds between the conductor segments 30 and the neutral bus bar 14, and extends to a position away from the axial end face of the stator core 11. In this case, the area between the resin sealing portion 61 and the core end face is a region without resin sealing, and this region can be used as a coil cooling portion that cools the stator winding 12. Note that possible methods for cooling the stator winding 12 include cooling using cooling oil or cooling water as a refrigerant (oil cooling, water cooling), and air cooling (air cooling).

[0035] Incidentally, it is conceivable that heat dissipation from the neutral bus bar 14 occurs via the insulating resin of the resin sealing portion 61, causing a drop in the temperature of the neutral bus bar 14. Specifically, it is conceivable that heat dissipation from the neutral bus bar 14 is promoted more than heat dissipation from the stator winding 12, for example, because the surface area of ​​the neutral bus bar 14 is larger than the surface area of ​​the stator winding 12, causing the temperature of the neutral bus bar 14 to become lower than the temperature of the stator winding 12. In this case, there is a concern that the drop in temperature of the neutral bus bar 14 may make it impossible to properly detect the temperature of the stator 10.

[0036] Therefore, in this embodiment, the resin sealing portion 61 is configured to have air bubbles around the neutral bus bar 14. This increases the thermal resistance of the insulating resin around the neutral bus bar 14, thereby suppressing heat dissipation from the neutral bus bar 14 via the insulating resin. A specific configuration will be described with reference to Fig. 8, which is a vertical cross-sectional view of the resin sealing portion 61 at a position that crosses the neutral bus bar 14.

[0037] As shown in Fig. 8, in the resin sealing portion 61, air bubbles B exist between the plate surface of the neutral bus bar 14 and the outer surface of the resin sealing portion 61. Fig. 8 shows a configuration in which the neutral bus bars 14 are arranged in two stages in the axial direction, with the air bubbles B existing on the upper surface side of the neutral bus bar 14 at the top of the figure, i.e., on the side opposite the stator core, and the air bubbles B existing on the lower surface side of the neutral bus bar 14 at the bottom of the figure, i.e., on the side closer to the stator core 11. However, the air bubbles B may also exist between the upper and lower bus bars.

[0038] When viewed in the longitudinal direction of the neutral bus bar 14, it is preferable that the air bubbles B are present along the longitudinal direction of the neutral bus bar 14. Furthermore, in a portion where the neutral bus bar 14 has one stage in the axial direction, it is preferable that the air bubbles B are present on at least one of the upper surface side and the lower surface side of the neutral bus bar 14.

[0039] By providing the air bubbles B around the neutral bus bar 14, the thermal resistance around the neutral bus bar 14 increases, suppressing heat dissipation from the neutral bus bar 14. It is possible that tiny air bubbles are dispersed inside the resin sealing portion 61, but it is preferable that the air bubbles are larger or contain a greater amount of air bubbles in the areas around the neutral bus bar 14 (the upper surface side of the upper bus bar and the lower surface side of the lower bus bar) than in other areas.

[0040] Furthermore, because the insulating resin of the resin sealing portion 61 and the neutral bus bar 14 have different linear expansion coefficients, cracks occur in the insulating resin due to distortion caused by temperature changes, and if the cracks progress to the outer surface of the resin sealing portion 61, there is a concern that heat dissipation from the neutral bus bar 14 may occur due to the intrusion of refrigerant. However, by providing air bubbles B around the neutral bus bar 14, the expansion of the insulating resin due to temperature increases is absorbed by the air bubbles B. This prevents cracks from occurring in the insulating resin, and suppresses heat dissipation from the neutral bus bar 14 due to the cracks.

[0041] 8, A1 is an area where the stator winding 12 (conductor segments 30) is sealed with resin, and A2 is an area where the neutral bus bar 14 is sealed with resin. Of the areas A1 and A2, area A2 around the neutral bus bar 14 is an air bubble area where more air bubbles B exist than area A1 around the stator winding 12.

[0042] In this case, since there are fewer bubbles B in the region A1 of the resin sealing portion 61, the inconvenience of reduced insulation between the phase windings (conductor segments 30) of each phase due to the presence of bubbles is suppressed.

[0043] It is thought that distortion of the insulating resin in the resin sealing portion 61 becomes large at the interface between the insulating resin and the neutral bus bar 14. In consideration of this, it is preferable to configure the insulating resin so that bubbles B are present in contact with the surface of the neutral bus bar 14, as shown in Fig. 9(a). This suppresses distortion of the insulating resin at the interface with the neutral bus bar 14, and ultimately suppresses heat dissipation from the neutral bus bar 14 due to cracks in the insulating resin.

[0044] Furthermore, it is believed that cracks are likely to occur in the resin sealing portion 61 at the portions in contact with the corners of the neutral bus bar 14 because stress caused by expansion and contraction of the insulating resin due to temperature changes in the stator 10 is concentrated therein. In consideration of this, it is preferable to configure the resin sealing portion 61 so that bubbles B are present near the corners of the neutral bus bar 14, as shown in Figure 9(b). This prevents cracks from occurring at the corners where stress is concentrated, and suppresses heat dissipation from the neutral bus bar 14 due to cracks in the insulating resin.

[0045] The neutral conductor bus bar 14 may be configured such that bubbles B are provided near uneven portions formed by bending or notching the main body 41. In this case, too, by arranging bubbles in stress concentration portions that are likely to become the starting points of cracks, it is possible to suppress the occurrence of cracks due to stress relaxation.

[0046] FIG. 10 is a diagram for explaining the molding of the resin sealing portion 61 in the coil end portion CE2.

[0047] The resin sealing portion 61 is formed after the neutral bus bar 14 is connected to the coil end portion CE2 of the stator winding 12. During the molding, the coil end portion CE2 is inserted into a mold 70 filled with a liquid resin material, and the resin sealing portion 61 is molded in this state. In this case, the resin sealing portion 61 is molded with the coil end portion CE2 immersed in the mold 70 with the coil end portion CE2 facing vertically downward.

[0048] When molding this resin sealing portion 61, it is preferable to provide air bubbles around the neutral bus bar 14. For example, as shown in Fig. 11(a), it is preferable to form the plate surface of the neutral bus bar 14 into a concave curved surface, and harden the resin material while air is trapped inside the curved surface.

[0049] Also, as shown in Figure 11(b), foamable resin R may be attached to the outer surface of the neutral bus bar 14, and in that state the neutral bus bar 14 may be immersed in a mold 70, and then the resin may be hardened to create air bubbles around the neutral bus bar 14.

[0050] Alternatively, air may be directly injected into the resin sealing portion 61 in the mold 70 using a tube or the like to provide air bubbles around the neutral bus bar 14.

[0051] According to the above embodiment, the following excellent effects are obtained.

[0052] Since the resin sealing portion 61 has air bubbles B around the neutral bus bar 14, the thermal resistance of the insulating resin around the neutral bus bar 14 increases, suppressing heat dissipation from the neutral bus bar 14 through the insulating resin. This suppresses a decrease in temperature of the neutral bus bar 14, and allows the temperature sensor 51 provided integrally with the neutral bus bar 14 to properly detect the temperature of the stator 10.

[0053] Heat from the neutral bus bar 14 is more likely to be released from the plate surface with the largest surface area among the outer surfaces of the bus bar. In this regard, since the configuration has air bubbles B between the plate surface of the neutral bus bar 14 and the outer surface of the resin sealing portion 61, heat release from the plate surface of the neutral bus bar 14 can be suppressed.

[0054] It is thought that cracks due to distortion are likely to occur in the resin sealing portion 61 at the interface between the insulating resin and the neutral bus bar 14. In this regard, the resin sealing portion 61 is configured so that bubbles B are present in contact with the surface of the neutral bus bar 14. In this case, the occurrence of cracks due to distortion caused by thermal stress is suppressed, and heat dissipation from the neutral bus bar 14 is suppressed. This suppresses a drop in temperature of the neutral bus bar 14, allowing the temperature of the stator 10 to be detected appropriately.

[0055] The portion of the resin sealing portion 61 surrounding the corner of the neutral bus bar 14 is an inside corner, and it is thought that stress will concentrate due to expansion and contraction of the insulating resin due to temperature changes, causing cracks. In this regard, the resin sealing portion 61 is configured so that bubbles B are present near the corner of the neutral bus bar 14, thereby reducing the stress generated near the corner of the neutral bus bar 14 and preventing cracks from occurring due to stress. This prevents a decrease in temperature of the neutral bus bar 14 and allows the temperature of the stator 10 to be detected properly.

[0056] In the resin sealing portion 61, the area around the neutral bus bar 14 is made into a bubble area where there are more bubbles B than around the stator winding 12. In other words, there are fewer bubbles B around the stator winding 12 than around the neutral bus bar. This prevents problems such as a decrease in insulation between the phase windings of each phase due to the presence of bubbles.

[0057] (Variation) The above-described embodiment may be partially modified. Modifications of the above-described embodiment will be described below.

[0058] The body 41 of the neutral bus bar 14 does not have to be folded back. In this case, too, it is preferable that air bubbles B are provided on the stator core 11 side and the opposite side of the neutral bus bar 14 to the stator core 11.

[0059] In the above embodiment, the stator winding 12 has a segment structure using the conductor segments 30, but this may be modified. For example, the stator winding 12 may be formed by winding a continuous wire around each slot 23 of the stator core 11 using wave winding.

[0060] Regarding the coil end portion CE2, an area without resin sealing is provided between the resin sealing portion 61 and the end face of the stator core 11, but instead, the resin sealing portion 61 may be provided over the entire coil end portion CE2 in the axial direction. [Explanation of symbols]

[0061] 10... stator, 11... stator core, 12... stator winding, 14... neutral bus bar, 51... temperature sensor, 61... resin sealing portion, CE2... coil end portion.

Claims

1. A stator (10) for a rotating electric machine comprising: a stator core (11); a stator winding (12) provided in the stator core; a neutral bus bar (14) connected to a coil end portion (CE2) of the stator winding; and a resin sealing portion (61) that seals the coil end portion and the neutral bus bar with insulating resin within a range including an axial tip end portion of the coil end portion and the neutral bus bar, The neutral bus bar has a folded portion at a longitudinal intermediate portion, and a temperature sensor (51) is provided in a state sandwiched between the folded portion, The resin-sealed portion is formed on both folded portions of the neutral bus bar, and has bubbles on surfaces other than the opposing surfaces that face each other at the folded portions.

2. The stator of claim 1 , wherein air bubbles are present in the resin-sealed portion near corners of the neutral bus bar.

3. 3. The stator of claim 1, wherein the resin-sealed portion has a pore region around the neutral bus bar where more pores exist than around the stator winding.

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