Electric motor, air conditioner, vacuum cleaner, and method for producing electric motor

An electric motor includes a stator, and a metal component that is in contact with the stator. The stator includes a first tooth, a second tooth, a first winding wound around the first tooth by concentrated winding, a second winding wound around the second tooth by concentrated winding, and a thermal conduction sheet held between the first winding and the second winding. The thermal conduction sheet is held between the metal component and the first winding in a deformed state.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national stage application of International Patent Application No. PCT/JP2017/025113 filed on Jul. 10, 2017, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an electric motor.

BACKGROUND

In recent years, with a reduction in size and weight of electric motors, the output density that is the ratio of the output to the mass of the electric motor is increasing. As the output density increases, the temperature of the electric motor rises. As the temperature of the electric motor rises, for example, the electrical resistance of a winding increases, the copper loss increases, and the efficiency of the electric motor thus lowers. When a rare-earth magnet containing Nd—Fe—B (neodymium-iron-boron) or a rare-earth magnet containing Sm—Fe—N (samarium-iron-nitrogen) is used as a permanent magnet for a permanent magnet synchronous electric motor, as the temperature of the electric motor rises, the magnetic force and the coercive force of the permanent magnet decrease, and the demagnetization resistance of the permanent magnet and the efficiency of the electric motor lower. Furthermore, as the temperature of the electric motor rises, an insulator insulating a stator and the surface (more specifically, an insulating coating) of the winding are damaged, and a quality failure of the electric motor may thus occur.

Of the total heat generated by the electric motor, heat from the winding resulting from copper loss, and heat from a stator core resulting from iron loss are dominant. The heat from the stator core is conducted to a frame covering the stator and is exhausted outside the electric motor. Although the winding is in contact with the insulator electrically insulating the stator, since the heat radiation effect of the insulator is small, the heat from the winding can be hardly exhausted outside the electric motor.

Hence, it is not easy to exhaust the heat from the winding outside the electric motor compared to the heat from the stator core, and the temperature of the winding rises more readily than that of the stator core. As the temperature of the winding rises, the electrical resistance of the winding increases and the copper loss increases, so that it results in a vicious cycle of a further rise in the temperature of the winding.

In view of this, a method has been proposed to bring a resin sheet serving as a thermal conduction sheet for conducting heat into contact with coil ends to conduct the heat from the winding to the frame serving as a heat radiating portion and exhaust this heat outside the electric motor (see, for example, patent reference 1).

PATENT REFERENCE

Patent Reference 1: Japanese Patent Application Publication No. H10-174371

In the conventional technique, however, a problem has arisen in that a portion in which the thermal conduction sheet is in contact with the winding is small, and the cooling performance is therefore insufficient. In the conventional technique, as another problem, in the process of producing the electric motor, since the thermal conduction sheet is easily detached from the winding, it is difficult to assemble the stator in the state where the thermal conduction sheet comes in contact with the winding.

SUMMARY

The present invention has been made in consideration of the above-described problems, and has an object to improve the cooling performance in the electric motor and facilitate assembly of the stator in a state where the thermal conduction sheet comes in contact with the winding with a simple configuration.

An electric motor according to an aspect of the present invention includes a stator, and a metal component that is in contact with the stator, the stator including a first tooth, a second tooth, a first winding wound around the first tooth by concentrated winding, a second winding wound around the second tooth by concentrated winding, a first thermal conduction sheet held between the first winding and the second winding and to conduct heat of the first winding to the metal component, and a second thermal conduction sheet held between the first winding and the second winding and to conduct heat of the second winding to the metal component, wherein the first thermal conduction sheet is wound around the first winding, the second thermal conduction sheet is wound around the second winding, the first thermal conduction sheet is held between the metal component and the first winding in a deformed state, and the second thermal conduction sheet is held between the metal component and the second winding in a deformed state.

According to the present invention, it is possible to improve the cooling performance in the electric motor and facilitate assembly of the stator in a state where the thermal conduction sheet comes in contact with the winding with a simple configuration.

FIG. 1is a sectional view schematically illustrating a structure of an electric motor1according to Embodiment 1 of the present invention.

In an x-y-z orthogonal coordinate system illustrated in each drawing, the z-direction (z-axis) indicates a direction (to be also referred to as the “axial direction of a rotor2” or simply as the “axial direction” hereinafter) parallel to an axis A1(that is, the axis of rotation of the rotor2) of a shaft10of the electric motor1, the x-direction (x-axis) indicates a direction perpendicular to the z-direction (z-axis), and the y-direction indicates a direction perpendicular to both the z- and x-directions.

The electric motor1is implemented as, for example, an inner rotor IPM (Interior Permanent Magnet) motor, but the present invention is not limited to this. The electric motor1may be implemented as, for example, an SPM (Surface Permanent Magnet) motor. The electric motor1is used as, for example, a fan motor or a blower motor.

The electric motor1includes the rotor2, a stator3, a frame4that is a metal frame as a metal component, bearings5aand5b, and a compression spring6. The upper side inFIG. 1will be referred to as a side A (also called a first side) hereinafter, and the lower side inFIG. 1will be referred to as a side B (also called a second side) hereinafter. In the example illustrated inFIG. 1, the side A corresponds to the load side, and the side B corresponds to the counter-load side, but the side B may correspond to the load side, and the side A may correspond to the counter-load side.

The bearings5aand5brotatably support the rotor2. The bearing5ais fixed on the side A (more specifically, a frame portion4a) of the frame4, and the bearing5bis fixed on the side B (more specifically, a frame portion4b) of the frame4.

The frame4covers the stator3. At least a part of the frame4is exposed outside the electric motor1. The frame4is made of a metal material such as iron or aluminum. In this Embodiment, the frame4includes the frame portions4aand4b. More specifically, the frame4is divided into two frames (that is, the frame portions4aand4b) in a plane perpendicular to the axis of rotation of the rotor2. Each of the frame portions4aand4bhas a cup shape.

The frame4includes an inner surface41a(first inner surface) formed on one end side (the side A illustrated inFIG. 1) in the axial direction, and an inner surface41b(second inner surface) formed on the other end side (the side B illustrated inFIG. 1) in the axial direction.

The frame portion4aincludes a flange portion42aformed on the opening side (the side B illustrated inFIG. 1), and the inner surface41a. The frame portion4asupports the rotor2on the side A via the bearing5a.

The frame portion4bincludes a flange portion42bformed on the opening side (the side A illustrated inFIG. 1), the inner surface41b, and a closed bottom portion42c. The frame portion4bsupports the rotor2on the side B via the bearing5b. The stator3is fixed in the frame portion4b.

The flange portion42aof the frame portion4ais in contact with the flange portion42bof the frame portion4b, and the flange portion42aof the frame portion4ais fixed to the flange portion42bof the frame portion4bby, for example, an adhesive, a screw, or welding.

The compression spring6is interposed between the bearing5band the closed bottom portion42cof the frame portion4b. The compression spring6applies a preload to the bearing5b. With this arrangement, a preload is also applied to the bearing5a. As the compression spring6, a wave washer, for example, is used.

The rotor2includes a rotor core7, a permanent magnet or permanent magnets8, end plates9aand9b, and the shaft10. The rotor2is inserted inside the stator3.

The rotor core7is formed by, for example, stacking, in the axial direction, a plurality of electrical steel sheets stamped into a predetermined shape. The cross-sectional shape (the two-dimensional shape perpendicular to the axial direction) of the rotor core7is a circle. A shaft hole11and a magnet insertion hole or magnet insertion holes12are formed in the rotor core7.

The shaft hole11is designed as a through hole formed in the axial direction. The shaft10is inserted into the shaft hole11. The center of the shaft hole11in the radial direction (to be also simply referred to as the “radial direction” hereinafter) of the stator3coincides with the center of the rotor core7in the radial direction.

In this Embodiment, a plurality of magnet insertion holes12are formed in the rotor core7at regular intervals in the circumferential direction of the stator3about the axis A1(to be simply referred to as the “circumferential direction” hereinafter). The magnet insertion holes12are designed as through holes formed in the axial direction. Each magnet insertion hole12is formed closer to the outer circumferential surface of the rotor core7than the shaft hole11. The permanent magnet8is inserted into each magnet insertion hole12.

The permanent magnet8is, for example, a rare-earth magnet. An example of the shape of the permanent magnet8is a rectangular parallelepiped.

The end plates9aand9bclose the opening portions, on the sides A and B, respectively, of the magnet insertion hole12. This prevents the permanent magnet8from falling off the magnet insertion hole12.

An example of the cross-sectional shape (the two-dimensional shape perpendicular to the axial direction) of the shaft10is a circle. The shaft10is rotatably supported by the bearings5aand5b.

FIG. 2is a plan view schematically illustrating a structure of the stator3. An arrow D1inFIG. 2indicates the circumferential direction of the stator3.

The stator3includes a stator core17formed in an annular shape, insulators16insulating the stator core17, windings18wound around the stator core17with the insulators16in between, thermal conduction sheets20to conduct heat, and slots21. The stator3is formed in an annular shape in the circumferential direction about the axis A1. The stator3(more specifically, the stator core17) is held by the frame4(more specifically, the frame portion4b). The rotor2is rotatably mounted inside the stator3.

The stator3includes at least one split core14. In this Embodiment, the stator3is formed of a plurality of split cores14(more specifically, nine split cores14). In the example illustrated inFIG. 2, the plurality of split cores14are arranged in an annular shape in the circumferential direction about the axis A1to form the stator3. The stator3is fixed in the frame4(more specifically, the frame portion4b) by a means such as press fitting or welding, and the outer circumferential surface of the stator core17is in contact with the interior of the frame portion4b.

The stator core17is formed by, for example, stacking, in the axial direction, a plurality of electrical steel sheets stamped into a predetermined shape. The stator core17includes at least one yoke portion15(also called a core back), and a plurality of teeth19projecting inwards in the radial direction. The stator core17is formed of a plurality of stator cores17asplit (to be also referred to as the “split stator cores17a” hereinafter). Therefore, each split stator core17aincludes the yoke portion15and the tooth19.

As illustrated inFIG. 2, the plurality of teeth19are arranged in a radial pattern about the axis A1, and these teeth19are arranged at regular intervals in the circumferential direction. A region surrounded by two yoke portions15and two teeth19is the slot21. The inner distal ends of the teeth19in the radial direction face the rotor2. An air gap is formed between the rotor2and the distal ends of the teeth19.

However, the stator3need not always be formed of the plurality of split stator cores17a. The stator core17may be formed by, for example, stacking a plurality of annular materials (for example, electrical steel sheets or amorphous materials such as amorphous metals).

FIG. 3is a diagram illustrating the plurality of split cores14that are connected to each other.

Each split core14includes the split stator core17a, the winding18, and the insulator16insulating the split stator core17a. The insulator16is made of an insulating material.

The stator3(more specifically, the stator core17) includes connecting portions13. In this Embodiment, the connecting portions13are thin portions on the two end sides of the yoke portion15in the circumferential direction. As illustrated inFIG. 3, a split core14(the uppermost split core14inFIG. 3) as a first split core is rotatably connected via the connecting portion13to a split core14as a second split core adjacent to the first split core. More specifically, the yoke portion15of one split stator core17ais rotatably connected via the connecting portion13to the yoke portion15of another split stator core17aadjacent to the former split stator core17a.

The plurality of split cores14may be connected to each other via a structure other than the connecting portions13illustrated inFIG. 3. For example, a projection formed on the yoke portion15of a first split core (for example, the uppermost split core14inFIG. 3) to project in the axial direction may be rotatably fitted into a recess formed in the yoke portion15of a second split core adjacent to the first split core.

The windings18are wound around the stator core17with the insulators16in between to form coils for generating a rotating magnetic field. More specifically, the windings18are wound around the teeth19by concentrated winding. In the winding18(that is, the coil) wound around the stator core17with the insulator16in between, an end side part on the side A in the axial direction is referred to as a coil end18a. In the winding18(that is, the coil) wound around the stator core17with the insulator16in between, an end side part on the side B in the axial direction is referred to as a coil end18b.

As the winding scheme of the windings18, concentrated winding is used, as described above. As illustrated in, for example,FIG. 3, in a state before the plurality of split cores14are arranged in an annular shape (for example, the state in which the plurality of split cores14are arranged linearly), the windings18can be wound around the split stator cores17a. The split stator cores17a(that is, the split cores14) having the windings18wound around them are folded in an annular shape and fastened together by welding or the like.

The thermal conduction sheets20are wound around the windings18. Accordingly, the thermal conduction sheets20are in contact with the windings18. However, the thermal conduction sheets20need not always be wound around all the windings18. The thermal conduction sheet20is made of, for example, a material containing silicone. The thermal conduction sheet20may be made of a material other than the material containing silicone, such as a material containing acrylic resin. The thickness of the thermal conduction sheet20is, for example, 1 mm to 3 mm. However, the thickness of the thermal conduction sheet20may be smaller than 1 mm, or may be larger than 3 mm.

FIG. 4is a sectional view taken along a line A4-A4inFIG. 1.

In the example illustrated inFIG. 4, a winding18(the left winding18in the example illustrated inFIG. 4) as a first winding is wound around a tooth19(the left tooth19in the example illustrated inFIG. 4) as a first tooth by concentrated winding with the insulator16in between. Similarly, a winding18(the right winding18in the example illustrated inFIG. 4) as a second winding is wound around a tooth19(the right tooth19in the example illustrated inFIG. 4) as a second tooth by concentrated winding with the insulator16in between.

The thermal conduction sheets20are wound around the windings18. In other words, in the state where the thermal conduction sheets20are wound around the windings18, the stator3is disposed in the frame portion4b, and the frame portion4ais combined with the frame portion4b. Accordingly, the thermal conduction sheets20are held between the frame4and the windings18in a deformed state. More specifically, a first portion20athat is a part of each thermal conduction sheet20is held between the coil end18aand the frame portion4ain a deformed state, and a second portion20bthat is another part of this thermal conduction sheet20is held between the coil end18band the frame portion4bin a deformed state.

Since the thermal conduction sheets20are in contact with the frame portions4aand4bof the frame4, heat from the windings18is conducted to the frame portions4aand4bof the frame4through the thermal conduction sheets20.

In this Embodiment, deformation of the thermal conduction sheets20is elastic deformation. In other words, the thermal conduction sheets20are held between the frame4and the windings18in an elastically deformed state. Each thermal conduction sheet20need only be held between the frame4and at least one coil end (that is, the coil end18aor18b). In addition, one of the plurality of thermal conduction sheets20need only be held between the frame4and any winding18(for example, the first winding) in a deformed state.

In the slot21, the thermal conduction sheets20are held between two teeth19adjacent to each other (more specifically, two windings18adjacent to each other) in a deformed state. In other words, third portions20cof the thermal conduction sheets20are sandwiched between two teeth19adjacent to each other (more specifically, two windings18adjacent to each other) in a deformed state and thus fixed.

In the example illustrated inFIG. 4, two thermal conduction sheets20are held between a winding18(the left winding18in the example illustrated inFIG. 4) as a first winding and a winding18(the right winding18in the example illustrated inFIG. 4) as a second winding. Two thermal conduction sheets20adjacent to each other are in contact with each other. At least one thermal conduction sheet20is further in contact with the frame4. With this arrangement, the thermal conduction sheets20conduct heat from the windings18to the frame4and exhaust the heat from the windings18outside the electric motor1.

Deformation of the thermal conduction sheets20may be plastic deformation. In this case, the thermal conduction sheets20are held between the frame4and the windings18in a plastically deformed state. For example, the first portions20aof the thermal conduction sheets20are held between the coil ends18aand the frame portion4ain a plastically deformed state, the second portions20bof the thermal conduction sheets20are held between the coil ends18band the frame portion4bin a plastically deformed state, and the third portions20cof the thermal conduction sheets20are held between two teeth19adjacent to each other (more specifically, two windings18adjacent to each other) in a plastically deformed state.

A method for producing the electric motor1will be described below.

FIG. 5is a flowchart illustrating an example of a process of producing the electric motor1. The method for producing the electric motor1includes the following steps.

In step S1, the plurality of split cores14are produced. For example, the stator core17is formed by stacking the plurality of electrical steel sheets in the axial direction. The insulator16is disposed on the side surfaces of the yoke portion15and the tooth19of the stator core17. The plurality of split cores14can be produced by winding a winding18around each tooth19by concentrated winding with the insulator16in between.

FIG. 6is a diagram illustrating an example of processing in step S2of the process of producing the electric motor1.

In step S2, in a state before the plurality of split cores14are arranged in an annular shape (for example, the state in which the plurality of split cores14are arranged linearly, as illustrated inFIG. 3), the thermal conduction sheets20are interposed between the windings18. In this Embodiment, the thermal conduction sheet20is wound around the winding18of each split core14, as illustrated inFIG. 6. In the example illustrated inFIG. 6, one of the thermal conduction sheets20(the left thermal conduction sheet20inFIG. 6) as a first thermal conduction sheet is wound around one of the windings18(the left winding18inFIG. 6) as a first winding, and another one of the thermal conduction sheets20(the right thermal conduction sheet20inFIG. 6) as a second thermal conduction sheet is wound around another one of the windings18(the right winding18inFIG. 6) as a second winding.

In the state where the plurality of split cores14are arranged linearly, a gap G is formed between two teeth19adjacent to each other, and therefore the thermal conduction sheets20can be easily wound around the windings18. The length of the gap G need only be set within the range in which the thermal conduction sheets20are deformable when the stator3is in an assembled state.

In step S3, the plurality of split cores14are folded in an annular shape, and the split cores14at the opposite ends are fastened together by welding or the like. More specifically, the plurality of split cores14are folded in an annular shape so that in a slot21, parts (more specifically, third portions20c) of the thermal conduction sheets20are held between two teeth19adjacent to each other (more specifically, two windings18adjacent to each other). With this operation, in the slot21, the thermal conduction sheets20(more specifically, the third portions20cof the thermal conduction sheets20) are held between the two teeth19adjacent to each other (more specifically, the two windings18adjacent to each other) in a deformed state. The stator3is thus formed.

In step S4, the stator3(that is, the plurality of split cores14and the plurality of thermal conduction sheets20) is fixed in the frame4. More specifically, the stator3is fixed in the frame portion4bby a means such as press fitting or welding. In fixing the stator3in the frame portion4b, the stator3is disposed in the frame portion4bso that the thermal conduction sheets20come in contact with the frame4. More specifically, in fixing the stator3in the frame portion4b, the stator3is disposed in the frame portion4bso that parts (more specifically, the second portions20b) of the thermal conduction sheets20are held between the frame4(more specifically, the frame portion4b) and parts (more specifically, the coil ends18b) of the windings18in a deformed state.

In step S5, the rotor2is produced. The rotor2is obtained by, for example, inserting the shaft10into the shaft hole11formed in the rotor core7. The permanent magnet8for forming magnetic poles may be mounted on the rotor core7in advance.

In step S6, the shaft10is inserted into the bearings5aand5b.

The order of steps S1to S6is not limited to that illustrated inFIG. 5. For example, steps S1to S4, and step S5can be executed concurrently with each other. Step S5may be executed earlier than steps S1to S4.

In step S7, the compression spring6is disposed on the closed bottom portion42cof the frame portion4b, and the rotor2is inserted inside the stator3together with the bearings5aand5b.

In step S8, the frame4is assembled. More specifically, the frame4is assembled by combining the frame portion4awith the frame portion4bso that the first portions20aof the thermal conduction sheets20are held between the coil ends18aand the frame portion4a. With this operation, the first portions20aof the thermal conduction sheets20are held between the coil ends18aand the frame portion4ain a deformed state, and the second portions20bof the thermal conduction sheets20are held between the coil ends18band the frame portion4bin a deformed state. However, each thermal conduction sheet20may be held between the frame4and at least one coil end (that is, the coil end18aor18b).

Through the above-mentioned processes, the electric motor1is assembled.

FIG. 7is a diagram illustrating another example of a method for disposing the thermal conduction sheet20.

A thermal conduction sheet20may be disposed on the stator3in a manner illustrated inFIG. 7, in place of the method for disposing the thermal conduction sheet20in above-described Embodiment 1. In the example illustrated inFIG. 7, one thermal conduction sheet20is alternately in contact with inner surfaces41aand41bin the circumferential direction. In other words, the thermal conduction sheet20is provided in the stator3so as to be located in the order of a first position P1, a slot21, and a second position P2in the circumferential direction. The first position P1is a position between a frame4on the side A (more specifically, the inner surface41aof the frame portion4a) and a winding18on the side A (more specifically, the coil end18a). The second position P2is a position between the frame4on the side B (more specifically, the inner surface41bof the frame portion4b) and a winding18on the side B (more specifically, the coil end18b).

A part of the thermal conduction sheet20is held between the frame4and the winding18at the first position P1, another part of the thermal conduction sheet20is held between two teeth19adjacent to each other (more specifically, two windings18adjacent to each other) in slot21, and still another part of the thermal conduction sheet20is held between the frame4and the winding18at the second position P2.

FIG. 8is a diagram illustrating still another example of the method for disposing the thermal conduction sheet20.

A plurality of thermal conduction sheets20may be disposed on the stator3in a manner illustrated inFIG. 8, in place of the method for disposing the thermal conduction sheet20in above-described Embodiment 1. In the example illustrated inFIG. 8, each thermal conduction sheet20is provided in the stator3so as to be located in the order of a first position P1, a slot21, and a second position P2in the circumferential direction. Each thermal conduction sheet20may be provided in the stator3so as to be located in the order of the second position P2, the slot21, and the first position P1in the circumferential direction.

A part of the thermal conduction sheet20is held between the frame4and one winding18at the first position P1, another part of the thermal conduction sheet20is held between two teeth19adjacent to each other (more specifically, two windings18adjacent to each other) in the slot21, and still another part of the thermal conduction sheet20is held between the frame4and another winding18at the second position P2.

Effects of the electric motor1according to Embodiment 1 (including the Modifications) and the method for producing the electric motor1will be described below.

Generally, of the total heat generated by an electric motor during driving of the electric motor, heat from windings (more specifically, heat generated due to copper losses), and heat from a stator core (more specifically, heat generated due to iron losses) are dominant. In the electric motor, although heat is generated not only from the windings and the stator core, but also from a rotor core (more specifically, heat generated due to iron losses), permanent magnets (more specifically, heat generated due to eddy current losses), and bearings (more specifically, heat generated due to mechanical losses), the heat from these components is lower than the heat from the windings and the stator core.

In this Embodiment, the stator3is disposed in the frame4(more specifically, the frame portion4b), and the stator core17is in contact with the frame4(more specifically, the frame portion4b). This makes it possible to conduct heat of the stator core17to the frame4and exhaust the heat of the stator core17outside the electric motor1.

Generally, since the winding has a circular cross-sectional shape, the area of a portion that is in contact with the insulator is small. Furthermore, the insulator normally exhibits low thermal conductivity. Therefore, heat from the winding is not easily conducted to the insulator. When the difference in temperature between the winding and the stator core is small, the heat conducted from the winding to the insulator is not easily conducted to the stator core. As a result, the heat from the winding is not easily exhausted outside the electric motor.

In this Embodiment, the thermal conduction sheets20are interposed between the coil ends18aand the frame portion4aand in close contact with the coil ends18aand the frame portion4a. This makes it possible to conduct heat of the windings18from the coil ends18ato the frame portion4athrough the thermal conduction sheets20and exhaust the heat of the windings18outside the electric motor1.

The thermal conduction sheets20are also interposed between the coil ends18band the frame portion4band in close contact with the coil ends18band the frame portion4b. This makes it possible to conduct heat of the windings18from the coil ends18bto the frame portion4bthrough the thermal conduction sheets20and exhaust the heat outside the electric motor1.

The thermal conduction sheets20are in close contact with adjacent windings18in an elastically or plastically deformed state in the slots21. With this arrangement, since the contact area of the thermal conduction sheet20is larger than in a structure in which the thermal conduction sheets20are in contact with only the coil ends18aand18b, heat of the windings18is more quickly conducted to the thermal conduction sheets20. As a result, the cooling performance of the electric motor1can be improved.

The thermal conduction sheets20are held by two windings18adjacent to each other in the slot21, and therefore it is possible to prevent the thermal conduction sheets20from detaching from the stator3.

By using thermal conduction sheets20having a modulus of elasticity, even if a component constituting the electric motor1deforms due to a change in temperature, since deformation of the thermal conduction sheets20makes it possible to absorb the deformation of the component of the electric motor1, contact with the frame4and contact with the windings18can be maintained.

In the process of producing the electric motor1, even if components constituting the electric motor1have dimensional variations, deformation of the thermal conduction sheets20makes it possible to absorb the dimensional variations. This makes it possible to bring the thermal conduction sheets20into contact with the windings18and the frame4.

In this Embodiment, heat of the windings18is conducted to the frame4through the thermal conduction sheets20and exhausted outside the electric motor1. However, heat of the windings18may be conducted to a metal component other than the frame4and exhausted outside the electric motor1. In other words, the metal component is not limited to the frame4as long as it allows heat of the windings18to be exhausted outside the electric motor1. In this case, the metal component that is in contact with the thermal conduction sheets20is implemented as, for example, a heat radiating fin. When the heat radiating fin is used, one end side of the heat radiating fin is in contact with the thermal conduction sheets20, and the other end side of the heat radiating fin is exposed outside the electric motor1. Accordingly, even when a metal component other than the frame4is used, heat of the windings18can be exhausted outside the electric motor1.

When the stator3is formed of the plurality of split cores14, the stator3can be easily assembled in the state where the thermal conduction sheets20are in contact with the windings18, in the process of producing the electric motor1. For example, in steps S2to S3of the above-mentioned process of producing the electric motor1, it is possible to wind the thermal conduction sheet20around the winding18of each split core14and then fold the plurality of split cores14in an annular shape. This makes it possible to hold the thermal conduction sheets20by two teeth19(more specifically, two windings18) in the slot21. As a result, the stator3can be easily assembled, and the production cost of the electric motor1can thus be cut.

The yoke portion15of one stator core17is rotatably connected at the connecting portion13to another yoke portion15of the adjacent stator core17. This makes it possible to easily fold the plurality of split cores14in an annular shape.

When the connecting portions13are thin, since they readily deform, the plurality of split cores14can be easily folded in an annular shape. In addition, since the number of components can be reduced, the production cost of the electric motor1can be cut.

In the electric motor according to Modification 1, one thermal conduction sheet20is alternately in contact with the inner surfaces41aand41bin the circumferential direction. In this case, there is no need to use a large number of thermal conduction sheets20, and therefore the production cost of the electric motor can be cut.

An air conditioner50according to Embodiment 2 of the present invention will be described below.

FIG. 9is a diagram schematically illustrating a configuration of the air conditioner50according to Embodiment 2 of the present invention.

The air conditioner50(for example, a refrigerating and air conditioning apparatus) according to Embodiment 2 includes an indoor unit51as a fan (first fan), refrigerant piping52, and an outdoor unit53as a fan (second fan) connected to the indoor unit51via the refrigerant piping52.

The indoor unit51includes an electric motor51a(for example, the electric motor1according to Embodiment 1), an air blower51bdriven by the electric motor51ato blow air, and a housing51ccovering the electric motor51aand the air blower51b. The air blower51bincludes, for example, blades driven by the electric motor51a.

The outdoor unit53includes an electric motor53a(for example, the electric motor1according to Embodiment 1), an air blower53b, a compressor54, and a heat exchanger (not illustrated). The air blower53bis driven by the electric motor53ato blow air. The air blower53bincludes, for example, blades driven by the electric motor53a. The compressor54includes an electric motor54a(for example, the electric motor1according to Embodiment 1), a compression mechanism54b(for example, a refrigerant circuit) driven by the electric motor54a, and a housing54ccovering the electric motor54aand the compression mechanism54b.

In the air conditioner50, at least one of the indoor unit51or the outdoor unit53includes the electric motor1described in Embodiment 1 (including the Modifications). More specifically, as a driving source for the air blower, the electric motor1described in Embodiment 1 is applied to at least one of the electric motors51aor53a. As the electric motor54aof the compressor54, the electric motor1described in Embodiment 1 (including the Modifications) may even be used.

The air conditioner50can perform an operation such as a cooling operation for blowing cold air from the indoor unit51, or a heating operation for blowing hot air from the indoor unit51. In the indoor unit51, the electric motor51aserves as a driving source for driving the air blower51b. The air blower51bcan blow conditioned air.

With the air conditioner50according to Embodiment 2, since the electric motor1described in Embodiment 1 (including the Modifications) is applied to at least one of the electric motors51aor53a, the same effect as that described in Embodiment 1 can be obtained. This makes it possible to prevent a failure of the air conditioner50due to heat generated by the electric motor. By using the electric motor1described in Embodiment 1 in the air conditioner50, the production cost of the air conditioner50can be cut.

By using the electric motor1according to Embodiment 1 (including the Modifications) as a driving source for a fan (for example, the indoor unit51), the same effect as that described in Embodiment 1 can be obtained. This makes it possible to prevent a failure of the fan due to heat generated by the electric motor.

By using the electric motor1according to Embodiment 1 (including the Modifications) as a driving source for the compressor54, the same effect as that described in Embodiment 1 can be obtained. This makes it possible to prevent a failure of the compressor54due to heat generated by the electric motor.

The electric motor1described in Embodiment 1 can be mounted not only in the air conditioner50, but also in an apparatus including a driving source, such as a ventilating fan, a household electrical appliance, or a machine tool.

FIG. 10is a side view schematically illustrating a vacuum cleaner90(also simply called a “cleaner”) according to Embodiment 3 of the present invention.

The vacuum cleaner90includes a main body91, a dust chamber92, a duct93, a suction nozzle94, and a gripping portion95.

The main body91includes an electric blower91ato generate suction force (suction air) and send dust to the dust chamber92, and an exhaust port91b. The electric blower91aincludes a fan (not illustrated), and an electric motor1to rotate the fan.

The dust chamber92is mounted on the main body91. However, the dust chamber92may be provided inside the main body91. The dust chamber92is implemented as, for example, a container including a filter to separate dust and air. The suction nozzle94is mounted at the distal end of the duct93.

When the vacuum cleaner90is turned on, power is supplied to the electric blower91a, which can thus be driven. During driving of the electric blower91a, dust is drawn from the suction nozzle94by suction using the suction force generated by the electric blower91a. The dust drawn from the suction nozzle94by suction is collected in the dust chamber92through the duct93. The air drawn from the suction nozzle94by suction is exhausted outside the vacuum cleaner90from the exhaust port91bthrough the electric blower91a.

The vacuum cleaner90according to Embodiment 3 includes the electric motor1described in Embodiment 1, and therefore has the same effect as that described in Embodiment 1.

In addition, since the vacuum cleaner90according to Embodiment 3 includes the electric motor1described in Embodiment 1, a failure of the vacuum cleaner90due to heat generated by the electric motor can be prevented. By using the electric motor1described in Embodiment 1 in the vacuum cleaner90, the production cost of the vacuum cleaner90can be cut.