Stator for rotary electric machine and rotary electric machine

Provided is a stator for a rotary electric machine which can suppress the mechanical effects of thermal expansion and contraction of a fixing member for fixing a temperature detector, on a temperature detection element. The stator for a rotary electric machine includes a stator coil, a temperature detection unit including a temperature detection element, a protection member extending in a longitudinal direction to cover the temperature detection unit, and a fixing member serving as a positioning mechanism for the temperature detection unit with respect to a stator coil. The fixing member includes a clamp portion for fixing the protection member, and the clamp portion clamps the protection member at a position where the clamp portion does not overlap the temperature detection element in a longitudinal direction of the protection member.

TECHNICAL FIELD

The present invention relates to a stator for a rotary electric machine and a rotary electric machine.

BACKGROUND ART

As a stator for a rotary electric machine which detects the temperature of stator windings with high precision and responsibility, the following structure is known. The stator for a rotary electric machine includes a stator core, stator windings, a neutral terminal for electrically connecting neutral points of respective phases of the stator windings, a temperature detection element, and a substantially cylindrical heat transfer unit made of metal and provided at the neutral terminal to cover a temperature detection element (e.g., see PTL 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In the technology disclosed in PTL 1, the substantially cylindrical heat transfer unit made of metal covers the temperature detection element. In this structure, the substantially whole circumference of the temperature detection element is covered by the heat transfer unit made of metal. Thus, contraction of metal at low temperature may cause compression of the temperature detection element from the whole circumference by the heat transfer unit made of metal. A compressive load may cause a reduction in accuracy of temperature detection, impossibility of temperature detection, or the like due to cracks, damage, or the like in the temperature detection element. Furthermore, since the temperature detection element is only covered by the heat transfer unit, thermal expansion of metal at high temperature may generate a gap between the temperature detection element and the heat transfer unit made of metal, and the temperature detection element may drop off the heat transfer unit. That is, the thermal expansion and contraction of the fixing member tends to mechanically affect the temperature detection element.

Solution to Problem

According to a first aspect of the present invention, a stator for a rotary electric machine includes a stator coil, a temperature detection unit which includes a temperature detection element, a protection member which extends in a longitudinal direction to cover the temperature detection unit, and a fixing member which serves as a positioning mechanism for the temperature detection unit with respect to the stator coil. The fixing member includes a clamp portion which fixes the protection member, and the clamp portion clamps the protection member at a position where the clamp portion does not overlap the temperature detection element in the longitudinal direction of the protection member. According to a second aspect of the present invention, a stator for a rotary electric machine includes a stator coil, a temperature detection element, a protection member which covers the temperature detection element, and a fixing member which serves as a positioning mechanism for the temperature detection element with respect to the stator coil. The fixing member includes a clamp portion which clamps the protection member, and an opposed portion which is opposed to the protection member to provide an air gap between the opposed portion and the protection member. The temperature detection element is disposed at a position at which the temperature detection element is opposed to the opposed portion across the air gap. According to a third aspect of the present invention, a rotary electric machine includes the stator according to the first aspect or the second aspect.

Advantageous Effects of Invention

According to the present invention, mechanical effects of thermal expansion and contraction of a fixing member on a temperature detection element can be suppressed.

DESCRIPTION OF EMBODIMENTS

First Embodiment

A first embodiment of a stator for a rotary electric machine according to the present invention is hereinafter described with reference toFIGS. 1 to 5.

FIG. 1is a schematic diagram illustrating an overall configuration of a rotary electric machine.

InFIG. 1, a rotary electric machine1is illustrated partly in cross-section to show the inside of the rotary electric machine1.

As illustrated inFIG. 1, the rotary electric machine1includes a housing10, a stator2having a stator core20fixed to the housing10, and a rotor3rotatably disposed in the stator. The rotary electric machine1includes a casing, the casing is constituted by a front bracket11, the housing10, and a rear bracket12, and the housing10constitutes a cooling water channel of the rotary electric machine, together with a water jacket13.

The rotor3is fixed to a shaft31supported by a bearing30A of the front bracket11and a bearing30B of the rear bracket12, and is rotatably held in the stator core20.

FIG. 2is a perspective view of the stator for a rotary electric machine according to the first embodiment of the present invention.

The stator2includes the stator core20having a plurality of slots circumferentially formed, stator windings4, and a temperature detector5for measuring the temperature of the stator windings4.

The stator core20is formed by axially stacking magnetic steel plates of predetermined thickness into an annular shape, and has a plurality of axial slots formed circumferentially on the inner peripheral side.

The stator windings4, that is, a stator coil is mounted in a slot of the stator core20via an insulator41formed of an insulation resin material into a sheet shape. The stator windings4are constituted by axially inserting a rectangular conductor40formed of copper into a substantially U-shape, into a slot of the stator core20, bending an opening side end of the rectangular conductor40, and electrically connecting the bent portions of the rectangular conductors by welding or the like.

Welded portions of the rectangular conductor40are covered by insulation resin material. Since the stator windings4are constituted by the rectangular conductor40, as described above, gaps between the stator windings4in coil ends42at both ends of the stator core20can be increased, compared with stator windings constituted by continuously multiply winding one round wire conductor. However, in the present invention, the stator windings4may be formed by the round wire conductor.

The stator windings4ofFIG. 2are windings of three-phase Y-connection, and includes U-phase stator windings, V-phase stator windings, and W-phase stator windings which are constituted by the rectangular conductor40. The stator windings4of the respective phases have output terminals43of U-phase, V-phase, and W-phase arranged at one end, and the other ends of the stator windings4of the respective phases constitute a neutral point44to which the U-phase, the V-phase, and the W-phase are connected. Thus, a three-phase AC circuit is formed.

At the neutral point44of the stator windings4, the temperature detector5for measuring the temperature of the stator windings4is fixed by a fixing member6. A fixing structure for the temperature detector5will be described in detail later.

The temperature detector5includes a temperature detection element50(seeFIG. 3). The temperature detection element50is a temperature sensor including a semiconductor having a large variation in electrical resistance value relative to a variation in temperature. The rotary electric machine1includes a control unit (e.g., inverter) which monitors the resistance value of the temperature detection element50to detect the temperature of the stator windings4. When the detected temperature of the stator windings4exceeds a defined value, the control unit restricts or terminates the performance of the rotary electric machine1to prevent the abnormal overheat of the stator windings4.

The temperature of the stator windings4is transmitted to the temperature detector5, the temperature of the temperature detection element50is changed, and the electrical resistance value of the temperature detection element50is changed. When heat transmission from the stator windings4to the temperature detector5is low, the change of temperature, that is, the change of resistance of the temperature detection element50is delayed in time relative to the change of temperature of the stator windings4.

As described above, in a case where the change of temperature of the temperature detection element50is delayed in time relative to the change of temperature of the stator windings4, for example, the performance of the rotary electric machine1needs to be limited or the defined value of the temperature of the stator windings4needs to be set smaller, in accordance with the delay in time to prevent the overheat of the stator windings4. However, such a configuration leads to insufficient performance of the rotary electric machine1. For sufficient performance of the rotary electric machine1, the temperature following property of the temperature detection element50to the stator windings4needs to be ensured.

FIG. 3is a perspective view of an exemplary structure of the temperature detector illustrated inFIG. 2. A structure of the temperature detector disposed at the stator windings4is described with reference toFIG. 3.

The temperature detector5includes, for example, the temperature detection element50, a sealing member51for sealing the temperature detection element50, a wire52connected to the temperature detection element50, and a protection member53. The temperature detection element50is constituted by a semiconductor including a sintered transition metal oxide including nickel, cobalt, or manganese. The sealing member51is formed of a hard material, such as, glass. The temperature detection element50and the sealing member51constitute a temperature detection element unit55. For example, the protection member53is structured so that a resin54, such as epoxy resin, for covering the temperature detection element unit55is enclosed in an insulation cover53aformed of a resin or the like. The protection member53is formed into a shaft shape extending linearly along the wires52to cover a pair of positive and negative wires52connected to the temperature detection element50. The wires52are connected to the control unit (not illustrated) of the rotary electric machine1, and the control unit has a controller which monitors the resistance value of the temperature detection element50.

Since the temperature detection element50is positioned in the temperature detector5, the thermal resistance from the stator windings4to the temperature detector5is desirably small to detect the temperature of the stator windings4with high precision and responsibility. That is, the temperature detector5and the stator windings4are desirably brought into direct contact with each other without an air gap between the temperature detector5and the stator windings4, or the temperature detector5and the stator windings4are desirably brought into contact with each other via a member having an excellent heat conductivity, such as metal, between the temperature detector5and the stator windings4.

Furthermore, when a stress, such as compression, is applied to the temperature detection element unit55from outside, the sealing member51including the hard material having low elasticity or the temperature detection element may be cracked or damaged, leading to reduction in detection accuracy or disabled detection due to wrong resistance value. The protection member53is positioned around the temperature detection element unit55, but the protection member53is also affected by heat, causing expansion or contraction, or transfer of an impact. Therefore, the temperature detection element unit55desirably has a structure in which no stress, such as compression, is applied to the temperature detection element unit55from outside, via the protection member53.

FIG. 4is an enlarged view of an area IV ofFIG. 2,FIG. 5(A)is a side view of a fixing structure for the temperature detector illustrated inFIG. 4,FIG. 5(B)is a schematic cross-sectional view ofFIG. 5(A), andFIG. 5(C)is a top view of the fixing structure for the temperature detector.

The stator windings4have upper surfaces on which the fixing member6is positioned to fix the temperature detector5.

The fixing member6is formed of a member, such as metal, having excellent rigidity and excellent heat conductivity. The fixing member6includes a main body portion60having a plate shape, a joint portion61extending from one end of the main body portion60, and a pair of front and rear crimped portions62aand62bprovided at the main body portion60and spaced apart from each other. The front crimped portion62ais provided near a boundary between the main body portion60and the joint portion61. The rear crimped portion62bis provided at the opposite end of the main body portion60to the front crimped portion62a. Each of the front and rear side end portions62aand62bhas a thin strip shape before crimping and is deformable into a bent shape. The front side end portion62aand the rear side end portion62bare separated from each other by a length larger than the length of the temperature detection element unit55. The front and rear crimped portions62aand62bare crimped to constitute a clamp portion for clamping the temperature detector5.

As illustrated inFIG. 4, the stator windings4include a U-phase neutral line44U, a V-phase neutral line44V, and a W-phase neutral line44W, as coil ends of the respective phases. The neutral lines44U,44V, and44W of U-phase, V-phase, and W-phase are circumferentially arranged on and along one end surface of the stator core20extending perpendicularly to the axis direction of the stator core20. The neutral lines44U,44V, and44W of U-phase, V-phase, and W-phase are joined at the neutral point44by welding or the like.

The joint portion61is joined at the ends of the neutral lines44U,44V, and44W of U-phase, V-phase, and W-phase by welding or the like, and in such a state, the fixing member6is arranged on the upper sides of the neutral lines44U,44V, and44W of U-phase, V-phase, and W-phase, in a circumferential direction along the neutral lines44U,44V, and44W. The joint portion61of the fixing member6may be joined at the neutral point44together with the neutral lines44U,44V, and44W of U-phase, V-phase, and W-phase. To join the fixing member6to the neutral lines44U,44V, and44W of U-phase, V-phase, and W-phase by welding, the fixing member6preferably uses a material consisting of or including the same contents as those of the neutral lines44U,44V, and44W.

Note that to join the fixing member6to the neutral lines44U,44V, and44W of U-phase, V-phase, and W-phase, crimping may be employed instead of welding.

A method of fixing the temperature detector5of the fixing member6is described.

While the joint portion61of the fixing member6is fixed to the neutral lines44U,44V, and44W of U-phase, V-phase, and W-phase, the temperature detector5is mounted on one side of the main body portion60of the fixing member6. At this time, as illustrated inFIGS. 5(B) and 5(C), the temperature detection element unit55of the temperature detector5is positioned between the front crimped portion62aand the rear crimped portion62b, in a longitudinal direction in which the protection member53extends. That is, each of the front and rear crimped portions62aand62bas the clamp portion does not overlap on the temperature detection element unit55.

In this state, the front and rear crimped portions62aand62bare wound on the outer periphery of the protection member53, and crimped to press the protection member53against the main body portion60of the fixing member6. Thus, as illustrated inFIGS. 5(A) to 5(C), the temperature detector5is held by the front and rear crimped portions62aand62bof the fixing member6.

The first embodiment of the present invention has the following effects. (1) The temperature detection element unit55of the temperature detector5is positioned between the front crimped portion62aand the rear crimped portion62bin a longitudinal direction being a direction in which the protection member53extends, and the front and rear crimped portions62aand62bas the clamp portion do not overlap the temperature detection element unit55. Thus, even if the main body portion60of the fixing member6is contracted by heat and compresses the temperature detector5, a clamping force, that is, a holding force of the protection member53of the temperature detector5is increased, but no direct compressive load is applied to the temperature detection element unit55. Accordingly, even if thermal expansion or contraction occurs in the fixing member6, cracks or damage in the temperature detection element50or sealing member51can be suppressed. That is, mechanical effects on the temperature detection element unit55can be suppressed.

(2) The front and rear crimped portions62aand62bof the fixing member6compress or hold the protection member53of the temperature detector5by crimping or the like, and the temperature detector5is held while being pressed against the fixing member6. Thus, even if the fixing member6is thermally expanded or contracted, the temperature detector5is always in contact with the fixing member6. That is, even if the fixing member6is thermally expanded or contracted, no air gap leading to the increase of thermal resistance is generated between the stator windings4, the fixing member6, and the temperature detector5, and excellent heat conductivity can be always ensured between the stator windings4and the temperature detector5.

(3) The front and rear crimped portions62aand62bof the fixing member6compress and hold the temperature detector5, while pressing the temperature detector5against the main body portion60of the fixing member6by crimping. Thus, even if an external load, such as vibration, is applied to the stator2, a property of holding the temperature detector5is high and dropping-off or the like of the temperature detector5can be suppressed.

(4) The fixing member6and the neutral lines44U,44V, and44W of U-phase, V-phase, and W-phase of the stator windings4are joined by welding. Thus, the change of temperature of the stator windings4is quickly transmitted to the temperature detector5via the fixing member6.

(5) The temperature detector5is arranged on the upper sides of the neutral lines44U,44V, and44W as the coil ends of U-phase, V-phase, and W-phase, in a circumferential direction along the neutral lines44U,44V, and44W. Thus, the temperature detector5has a reduced height relative to a temperature detector5structured to be arranged in the axis direction of the stator core20. Furthermore, in a structure in which the temperature detector5is arranged in the axis direction of the stator core20, wires52of the temperature detector5need to be bent extremely to the neutral lines44U,44V, and44W, but in the present embodiment, the bending is not required.

Second Embodiment

FIG. 6is a perspective view of a second embodiment of the present invention.FIG. 6illustrates a state in which the protection member53of the temperature detector is partially removed, and the temperature detection element unit55is exposed.

The second embodiment has a structure in which the fixing member6is provided with a pair of crimped portions62cand62d, and both of the pair of crimped portions62cand62dare provided on the main body portion60, in back of the temperature detection element unit55.

As illustrated inFIG. 6, both of the pair of crimped portions62cand62dof the fixing member6are provided spaced apart from each other near the opposite end of the main body portion60to the joint portion61. The crimped portion62cis arranged near the temperature detection element unit55, and the crimped portion62dis arranged near the end of the main body portion60. The temperature detection element unit55constituted by the temperature detection element50and the sealing member51is arranged in front of the crimped portion62cso that the temperature detection element unit55does not overlap the crimped portion62c.

The second embodiment shows an exemplary structure in which the joint portion61of the fixing member6is joined to the neutral point44to which the neutral phases44U,44V, and44W of U-phase, V-phase, and W-phase are joined.

In the second embodiment, the other structures are similar to those of the first embodiment, and corresponding members are denoted by the same reference signs and description thereof will be omitted. The second embodiment also has the effects (1) to (5) of the first embodiment.

Third Embodiment

FIG. 7(A)is a perspective view of an area of a third embodiment of the present invention corresponding to the area of the first embodiment illustrated inFIG. 4, andFIG. 7(B)is a schematic cross-sectional view of a fixing structure for a temperature detector illustrated in FIG.7(A).

The third embodiment includes a structure in which the fixing member6has a crimped portion62eformed into a cylindrical shape having an inner hollow portion, and an opening portion63for exposing a portion of the protection member55corresponding to the temperature detection element unit55is formed in the crimped portion62e. The opening portion63of the crimped portion62eis positioned at substantially the center of the crimped portion62ein a longitudinal direction.

The crimped portion62eis formed deformable, having a thin thickness. To fix the temperature detector5to the fixing member6, the temperature detector5is inserted into the hollow portion of the crimped portion62e, and in such a state, the crimped portion62eof cylindrical shape is flattened to secure the temperature detector5. The crimped portion62eis formed such that, for example, a rectangular portion extending from one side surface60aof the main body portion60is provided, and the rectangular portion is bent into a round shape around an axis parallel to a longitudinal direction. The crimped portion62eis preferably flattened toward the main body portion60, in other words, downward from above. However, the crimped portion62emay be flattened in a direction perpendicular to a vertical direction, or may be radially flattened uniformly. In short, the crimped portion62eis desirably flattened in a direction crossing a longitudinal direction in which the protection member53extends. The temperature detection element unit55of the temperature detector5is set at a position corresponding to the opening portion63of the crimped portion62ein the longitudinal direction, and the crimped portion62eas the clamp portion does not overlap the temperature detection element unit55.

In the third embodiment, the other structures are similar to those of the first embodiment, and corresponding members are denoted by the same reference signs and description thereof will be omitted.

The third embodiment also has the effects (1) to (5) of the first embodiment.

The third embodiment is similar to the first embodiment in structure in which the temperature detector5is clamped in front and back of the temperature detection element unit55by the crimped portion62e. However, in the third embodiment, since the crimped portion62ehas a united member, crimping is required only once for excellent working efficiency.

Fourth Embodiment

FIG. 8(A)is a perspective view of an area of a fourth embodiment of the present invention corresponding to the area of the first embodiment illustrated inFIG. 4, andFIG. 8(B)is a schematic cross-sectional view of a fixing structure for a temperature detector illustrated inFIG. 8(A). The fourth embodiment is similar to the third embodiment in that the fixing member6includes a crimped portion62fhaving a cylindrical shape. However, the fourth embodiment includes a structure in which the crimped portion62fdoes not include the opening portion63of the third embodiment, but includes a protrusion64radially protruding at substantially the center in a longitudinal direction. As illustrated inFIG. 8(B), the protrusion64of the crimped portion62fprotrudes toward a side opposite to the main body portion60. The temperature detector5is secured by the fixing member6while the temperature detection element unit55is arranged in the area of the protrusion64of the crimped portion62fin the longitudinal direction. In this state, an air gap S is formed between the temperature detector5and the protrusion64of the crimped portion62f. That is, the crimped portion62fof the fixing member6includes a clamp portion for clamping the protection member53of the temperature detector5, and an opposed portion opposed to the protection member53to provide the air gap S between the opposed portion and the protection member53, and the temperature detection element unit55is arranged at a position at which the temperature detection element unit55is opposed to the opposed portion across the air gap S.

The crimped portion62fcan be made by a method similar to that described in the third embodiment. However, the rectangular portion needs to be bent into a round shape after a recessed portion for forming the protrusion64is formed in the rectangular portion extending from the one side surface60aof the main body portion60.

To fix the temperature detector5to the fixing member6of the fourth embodiment, the temperature detector is inserted into the hollow portion of the crimped portion62f. The temperature detector5is positioned so that the temperature detection element unit55corresponds to the protrusion64of the crimped portion62f. Then, the crimped portion62fis flattened at portions in front and back of the protrusion64in the longitudinal direction to secure the temperature detector5. Thus, as illustrated inFIG. 8(B), a structure can be obtained in which the temperature detection element unit55of the temperature detector5, arranged in the area of the protrusion64of the crimped portion62fin the longitudinal direction, is secured by the fixing member6.

In the fourth embodiment, the other structures are similar to those of the first embodiment, and corresponding members are denoted by the same reference signs and description thereof will be omitted.

The fourth embodiment also has the effects (1) to (5) of the first embodiment.

Furthermore, since the crimped portion62fhas a front portion and a rear portion united as one member across the temperature detection element unit55as in the third embodiment, excellent working efficiency is provided as in the third embodiment.

Note that in the fourth embodiment, a diameter of the hollow portion of the crimped portion62fmay be formed in a size large enough to loosely insert the temperature detector5in the longitudinal direction as a whole, flattening and crimping the portions of the crimped portion62fcorresponding to portions in front and back of the temperature detection element unit55while the temperature detector5is arranged in the hollow portion. According to this method, the crimped portion62fcan be readily formed inexpensively.

The temperature detectors5in the respective embodiments are by way of examples only, and another structure may be employed.

FIGS. 9(A) and 9(B)are each a schematic side cross-sectional view of a temperature detector according to a modification.

The temperature detector5A illustrated inFIG. 9(A)includes the temperature detection element50, the sealing member51for sealing the temperature detection element50, the wire52connected to the temperature detection element50, and a protection member57for covering the sealing member51and the wire52. The temperature detection element50and the sealing member51constitute the temperature detection element unit55. The temperature detector5A is different from the temperature detector5illustrated inFIG. 3, in that the protection member57does not include the insulation cover53aand is made of only resin.

The temperature detector5B illustrated inFIG. 9(B)includes the temperature detection element50, the wire52connected to the temperature detection element50, and a protection member57for covering the temperature detection element50and the wire52. The temperature detector5B is different from the temperature detector5A in that the sealing member51for sealing the temperature detection element50is not provided. That is, in the temperature detector5B, the temperature detection element50constitutes the temperature detection element unit55. Since the temperature detector5B does not include the sealing member51, there is no crack or damage in the sealing member51. Thus, when the temperature detector5B is used, the crimped portions62ato62fare arranged at positions at which the crimped portions62ato62fdo not overlap the temperature detection element50in the longitudinal direction of the protection members53and57.

The various embodiments and modifications have been described above, but the present invention is not limited to the contents thereof. The other embodiments conceivable within the technical scope of the present invention are also included in the scope of the present invention.

REFERENCE SIGNS LIST