JP7535686B2 - Motor - Google Patents

Description

The present invention relates to a motor. In particular, the present invention relates to the configuration of a stator coil of a motor.

In recent years, the demand for motors has been increasing in industrial and automotive applications. As a result, there is a demand for improved motor efficiency and lower costs.

One method of improving motor efficiency is known to be to increase the space factor of the stator coils placed inside the stator slots. By increasing the space factor of the stator coils, it is possible to reduce losses caused by the current flowing through the stator coils when the motor is running.

As a method for improving the space factor of the stator coil, a configuration such as placing a cast coil made of copper material inside the slot has been shown (see, for example, Patent Document 1).

One of the factors that reduces motor efficiency is the temperature rise caused by heat generation such as copper loss in the stator coil and iron loss in the stator core. It is known that a coolant is circulated inside the motor to dissipate heat and suppress the temperature rise (see, for example, Patent Document 2).

When the space factor of the stator coil is improved, the dead space in the slot is reduced. However, the dead space constitutes part of the refrigerant flow path, and reducing the dead space in the slot is equivalent to narrowing the refrigerant flow path, which reduces the flow rate of the refrigerant. As a result, the cooling effect of the refrigerant is not as effective. The temperature rise caused by heat generation in the stator coil or stator core becomes excessive, leading to a decrease in motor efficiency.

Motor efficiency is the ratio of the mechanical output from the motor to the power input to the motor, expressed as a percentage (unit symbol [%]). Space factor is the proportion of the conductor portion of the conductor, etc., to the cross-sectional area of the winding accommodating portion of the slot or insulator. If the cross section of the conductor, etc., is circular, dead space will be created between adjacent circles, so there is a limit to how much the space factor can be increased. In addition, the thickness of the insulating coating of the conductor, etc., is also a factor that reduces the space factor. Incidentally, if the thickness of the insulating coating of a conductor is constant, the smaller the diameter of the conductor, the higher the ratio of the thickness of the insulating coating or the area occupied by the insulating coating.

On the other hand, as the space factor of the stator coils placed in the stator slots increases, losses due to eddy currents generated in the stator coils may become noticeable. For this reason, a method for reducing eddy currents in the coils has been proposed, such as using a conductor in the stator coil whose cross section is composed of multiple regions in the collective conductor (see, for example, Patent Document 3).

The stator coil is excited by receiving an alternating current from the outside. Naturally, the magnetic flux generated in the stator, including the stator coil, is alternating magnetic flux. This alternating magnetic flux has the stator core and rotor core as its main magnetic path. However, some of the alternating magnetic flux becomes leakage magnetic flux and links with parts other than the stator core and rotor core. It has long been known that one of the locations with the most leakage magnetic flux is the tip side of the teeth of the stator core. When the conductor cross section is a circular conductor, the conductor area that links with the leakage magnetic flux is limited. For this reason, eddy currents generated in the conductor are not noticeable.

On the other hand, in order to increase the space factor of the stator coil, a spiral laminated coil with a spiral surface is constructed using a conductor with an elongated cross-sectional shape in which the width dimension at the conductor cross-section is greater than the thickness dimension at the conductor cross-section. In this case, the conductor area where leakage magnetic flux interlinks is several times larger than in the case of a conductor with a circular conductor cross-section. This results in significant generation of eddy currents.

The stator coil is excited by receiving an alternating current from the outside. Naturally, the magnetic flux generated in the stator, including the stator coil, is alternating magnetic flux. This alternating magnetic flux has the stator core and rotor core as its main magnetic path, but some of the alternating magnetic flux becomes leakage magnetic flux and links with parts other than the stator core and rotor core. It has long been known that one of the locations with the most leakage magnetic flux is the tip side of the teeth of the stator core. When the conductor cross section is a circular conductor, the conductor area with which the leakage magnetic flux links is limited, so eddy currents generated in the conductor are not noticeable.

On the other hand, in order to increase the space factor of the stator coil, a spiral laminated coil with a spiral surface is constructed using a conductor with an elongated cross-sectional shape in which the width dimension at the conductor cross-section is greater than the thickness dimension at the conductor cross-section. In this case, the conductor area where leakage magnetic flux interlinks is several times larger than in the case of a conductor with a circular conductor cross-section, and the generation of eddy currents becomes significant. For example, depending on the size of the stator coil, the resistivity of the material, or the driving conditions of the motor, heat generation can become large and the losses cannot be ignored. This has led to issues such as a decrease in the efficiency of the motor.

As a conventional example, Figs. 4A, 4B, and 4C are shown. Fig. 4A is a front view of a stator coil 5 as an example of the conventional example. Fig. 4B is a perspective view of a stator coil 5 as an example of the conventional example. Fig. 4C is a side view of a stator coil 5 as an example of the conventional example. In the stator coil 5, eddy currents 45 are generated in the coil wire path portion 5q of each turn, as shown by the dotted line and arrow A shown virtually in Fig. 4A. The eddy currents 45 generate Joule heat, which causes losses and reduces the efficiency of the motor. Furthermore, the self-temperature rise of the motor itself due to the eddy currents leads to an increase in copper loss of the motor itself.

DE 10 2012 212 637 A1 JP 2015-109733 A JP 2009-199749 A

The present invention provides a stator coil that has improved heat dissipation properties against heat generated by eddy currents, even when the space factor of the stator coil is increased. The present invention aims to improve the characteristics of the stator coil and motor compared to conventional techniques.

In order to solve the problem, the first invention is a motor including a stator core including a laminated body in which a plurality of stator core sheets are laminated, a stator including a stator coil in which the teeth of the stator core are part of the magnetic core, and a rotor rotatably supported by the tips of the teeth of the stator core through a gap, in which the stator coil has a conductor portion of the stator coil and a conductor portion including an insulating coating that covers the conductor portion, and the cross-sectional shape of the conductor portion is substantially rectangular, the stator coil is a coil with a predetermined number of turns and includes a substantially continuous spiral surface between the first turn of the stator coil and the last turn of the stator coil, two opposing sides of the four sides of the rectangular cross-sectional shape are included in the spiral surface, and the motor includes a missing structure portion that is missing from the side facing the outer diameter direction of the stator core to the side facing the direction in which the rotor is located in a part of the coil end portion that is the direction in which the stator core is laminated and where the stator coil protrudes beyond the end face of the stator core.

The second invention is a motor according to the first invention, in which the recessed structure is a grooved portion recessed in a groove shape in a portion of the coil end portion from the side facing the outer diameter direction of the stator core to the side facing the direction in which the rotor is positioned.

The third invention is a motor according to the first invention, in which the recessed structure is a hole that is recessed in a portion of the coil end from the side facing the outer diameter of the stator core to the side facing the direction in which the rotor is positioned.

According to the present invention, it is possible to provide a motor with improved stator coil characteristics compared to conventional stator coils by discovering a stator coil with improved heat dissipation properties against heat generated by eddy currents, even when the space factor of the stator coil is increased.

FIG. 1 is a top view showing a motor according to a first embodiment; FIG. 1 is a side view showing a motor according to a first embodiment; 1C-1C line in FIG. 1B. FIG. 1 is a front view of a stator coil according to a first embodiment; FIG. 13 is a front view of a stator coil according to the second embodiment; FIG. 1 is a front view of a stator coil as an example of a conventional example. FIG. 1 is a perspective view of a stator coil as an example of a conventional example. FIG. 1 is a side view of a stator coil as an example of a conventional example.

The motor of the present invention will be described below with reference to the drawings as appropriate. Note that each embodiment described below is merely an example and is not intended to limit the present invention, its applications, or its uses.

(Embodiment 1)
[Motor structure]
Fig. 1A is a top view showing the motor according to the first embodiment. Fig. 1B is a side view showing the motor according to the first embodiment. Fig. 1C is a cross-sectional view taken along line 1C-1C in Fig. 1B. However, in either case, insulating materials such as a cover case and an insulator are not shown. The motor 1 includes a shaft 2, a rotor 3, a stator 4, an insulator (not shown), stator coils U11, U22, U32, U41, V12, V21, V31, V42, W11, W22, W32, W41, and bus bars 51, 52, 53, and 54 inside a cover case (not shown).

Here, the longitudinal direction of the shaft 2 (the direction perpendicular to the paper surface of FIG. 1A) is referred to as the Z-axis direction, and the directions perpendicular to this (the direction parallel to the paper surface of FIG. 1A) are referred to as the X-axis direction and the Y-axis direction.

In addition, "integral" or "integrated" refers to the state of a single object in which multiple parts are not only mechanically connected by bolting or crimping, but also electrically connected by material bonds such as covalent bonds, ionic bonds, and metallic bonds, or in which all the parts are materially bonded and electrically connected by melting or other methods.

A coolant (not shown) circulates inside the motor 1, and the motor's heat is cooled by the coolant. The coolant flows from the upstream part where the coolant circulates to the downstream side, and then returns to the upstream part again, using the gaps in the stator core, stator coil, and rotor periphery as flow paths. Part of the coolant flow path is equipped with a heat dissipation part for cooling the coolant. The coolant may be circulated by a device that performs forced circulation. By providing such a configuration, the rotor 3 and stator 4 are cooled.

The rotor 3 is provided in contact with the outer periphery of the shaft 2. The rotor 3 includes magnets 31, whose north and south poles are arranged alternately along the outer periphery of the shaft 2, facing the stator 4. Note that neodymium magnets are used as the magnets 31 used in the rotor 3, but the material, shape, and composition can be changed as appropriate depending on the motor output, etc.

The stator 4 has a substantially annular stator core 41, a number of teeth 42 arranged at equal intervals along its inner circumference, and slots 43 arranged between each of the teeth 42. When viewed from the Z-axis direction, the stator 4 is disposed outside the rotor 3 at a fixed distance from the rotor 3.

The stator core 41 is configured as an assembly of multiple core segments. The core segment is configured to include a yoke 44 and multiple teeth 42. The core segment may be configured in any suitable manner other than that illustrated in this embodiment. For example, the yoke 44 is in the shape of a single ring. However, the yoke 44 may be configured to include multiple fan-shaped core segments, and these fan-shaped core segments may be arranged in a ring shape. The stator core 41 and each core segment are laminated bodies configured by stacking and integrating multiple core sheets (stator core sheets 41a) made by punching electromagnetic steel sheets containing silicon or the like into a predetermined shape.

In this embodiment, the rotor 3 has a total of 10 magnetic poles, including 5 north poles and 5 south poles that face the stator 4. The number of slots 43 is 12. However, the number of magnetic poles and the number of slots 43 of the rotor 3 are not limited to this. Other combinations of the number of magnetic poles and the number of slots are also applicable.

The stator 4 has 12 stator coils U11, U22, U32, U41, V12, V21, V31, V42, W11, W22, W32, and W41. The stator coils are attached to each tooth 42. When viewed from the Z-axis direction, the stator coils are arranged in each slot 43. In other words, the stator coils U11, U22, U32, U41, V12, V21, V31, V42, W11, W22, W32, and W41 are concentratedly wound around the teeth 42. Furthermore, the stator coils U11, U22, U32, and U41 are integrated with the bus bar 51, the stator coils V12 to V42 are integrated with the bus bar 52, and the stator coils W11 to W41 are integrated with the bus bar 53. Here, a bus bar may or may not be configured, and the connection may be via a wiring board or lead wires, etc.

Here, the first letter of the symbols UXY, VXY, and WXY representing the stator coils represents each phase of the motor 1 (U-phase, V-phase, and W-phase in this embodiment). The second letter represents the arrangement order of the stator coils in the same phase. The third letter represents the winding direction of the spiral coil that is the stator coil. In this embodiment, 1 represents the clockwise direction, and 2 represents the counterclockwise direction. Therefore, the stator coil U11 represents the first stator coil in the arrangement order of the U phase, and the winding direction is clockwise. The stator coil V42 represents the fourth stator coil in the arrangement order of the V phase, and the winding direction is counterclockwise. Note that clockwise means right-handed when viewed from the center of the motor 1, and counterclockwise means left-handed when viewed from the center of the motor 1.

Strictly speaking, stator coils U11 and U41 are U-phase stator coils, and stator coils U22 and U32 are U-bar phase stator coils (which generate a magnetic field in the opposite direction to that of the U-phase stator coil). However, in the following explanation, unless otherwise specified, they will be collectively referred to as U-phase stator coils. Similarly, stator coils V12 to V42 and stator coils W11 to W41 will be collectively referred to as V-phase stator coils and W-phase stator coils, respectively.

[Structure of the stator coil]
FIG. 2 is a front view of the stator coil according to the first embodiment. The stator coil 5 according to the present embodiment, configured as shown in FIG. 2, is applied to the stator coils U11, U22, U32, U41, V12, V21, V31, V42, W11, W22, W32, and W41 attached to the teeth 42 of the motor 1 shown in FIG. 1C. The stator coil 5 has a spiral structure including an annular body 5m with a predetermined number of turns. As shown in FIG. 2, the configuration of each turn of the annular body 5m is substantially rectangular in plan view. In FIG. 2, the long sides of the short-shaped portion of the annular body 5m in plan view are located on the side of the surface on which the lamination surface of the stator core sheet 41a appears in the teeth, and are referred to as the coil wire path portion 5q. The short sides of the short-shaped portion of the annular body 5m in plan view are located between the ends of the coil wire path portion 5q, which are the pair of long sides, in the same direction, and are referred to as the coil end portion 5r. The coil end portion 5r is in the direction in which the multiple stator core sheets 41a in the stator core 41 are stacked, and is also a portion where the stator coil 5 protrudes beyond the end face of the stator core 41.

The transition from one side of the coil wire path portion 5q to one side of the coil end portion 5r is called the coil corner portion 5s.

The stator coil 5, which is a spiral coil, has a conductor portion 5g , an insulating coating 5b provided on the surface of the conductor portion 5g , and a lead portion 5c and a lead portion 5d from the first turn 5t and the tenth turn 5u of the stator coil 5, respectively. The annular body 5m, which is the second turn to the tenth turn 5u of the stator coil 5, is substantially a rectangular ring in a plan view. The annular body 5m has two short sides, two long sides, and four coil corner portions 5s. In FIG. 2, each of the annular bodies 5m from the first turn 5t to the ninth turn is configured to make one turn in an annular shape. On the other hand, the tenth turn 5u is configured such that the annular shape does not complete one turn, and the short side of the annular body 5m is missing by about one turn. To express this configuration in another way, the tenth turn 5u is configured such that the annular shape does not complete about a quarter turn, and it is substantially three-quarters (3/4) turns. The reason why the tenth turn 5u is less than about a quarter of a turn is due to the arrangement of the lead-out portion 5c and the lead-out portion 5d. Depending on the arrangement positions of the lead-out portion 5c and the lead-out portion 5d, the tenth turn 5u may complete one turn or may complete slightly more than one turn. Similarly, the first turn 5t may complete less than one turn or may complete slightly more than one turn.

The conductor portion 5a has a conductor with a rectangular cross section and an insulating coating 5b that covers the conductor. The conductor portion 5a is a structure in which ring-shaped structures are stacked in a spiral shape. The spirally stacked configuration is a structure in which layers are stacked in the radial inward and outward directions of the motor. The spirally stacked configuration includes a ring-shaped body 5m with a predetermined number of turns. For example, the predetermined number of turns consists of the first turn 5t to the nth turn (n is an integer of 2 or more). The first turn 5t to the nth turn are referred to as a turn row.

The conductor portion 5g is a wire made of a conductive material having a substantially rectangular cross section. The wire forms an annular body 5m, which is then spirally stacked for 10 turns to form a single-layer structure, thereby forming a spiral coil of the conductor portion 5g . The conductor portion 5g is formed of, for example, copper, aluminum, zinc, magnesium, brass, iron, SUS (Steel Use Stainless), etc. These are described as single layers. However, the present invention can be applied not only to single-layer coils but also to multi-layer coils.

In the following explanation, the portion wound from the tip of the pull-out portion 5c to below the position where the pull-out portion 5d is provided will be referred to as the first turn 5t. The subsequent portions wound one turn at a time will be counted in order as the second turn, the third turn, ... the tenth turn 5u. The method of determining the starting point of each turn can be determined arbitrarily. The side of the stator coil 5 where the first turn 5t is provided will be referred to as the "outside", and the side where the tenth turn 5u is provided will be referred to as the "inside". This is because, in the radial direction of the motor structure, the outside of the motor is referred to as the "outside" and the center side of the motor is referred to as the "inside".

The insulating coating 5b is provided on the entire surface of the conductor portion 5g so as to insulate the stator coil 5 from an external member (not shown). For example, in the motor 1 shown in Figures 1A, 1B, and 1C, the insulating coating 5b and an insulating member (not shown), such as insulating paper, insulate the stator coil 5 from the stator core 41 and the teeth 42. Adjacent turns of the stator coil 5 are insulated by the insulating coating 5b. The insulating coating 5b is formed of, for example, polyimide, nylon, PEEK (Poly Ether Ether Ketone), acrylic, amide-imide, ester-imide, enamel, heat-resistant resin, or the like. The thickness of the insulating coating 5b is about several tens of micrometers, for example, between 5 μm and 50 μm.

The lead-out portions 5c and 5d are both parts of the conductor portion 5a. The lead-out portions 5c and 5d extend outward from the side surface of the stator coil 5, in other words, from a plane intersecting with the turn row of the conductor portion 5a, in order to receive a current supply from the outside or to supply a current to the outside. In order to connect to an external member, for example, any of the bus bars 51, 52, 53, and 54 shown in Figures 1A, 1B, and 1C, the insulating coating 5b is removed from the lead-out portions 5c and 5d. Note that the insulating coating 5b does not need to be removed from the entire area of the lead-out portions 5c and 5d. For example, it is sufficient that the insulating coating 5b is removed only from the portion required for connection to the bus bars 51, 52, 53, and 54.

Here, the features of the shape of the stator coil 5 according to the present embodiment will be described in detail. The stator coil 5 has a conductor portion 5a including a conductor portion 5g and an insulating coating 5b that covers the conductor portion 5g. The stator coil 5 includes a configuration in which the cross-sectional shape of the conductor portion 5a is substantially rectangular, a configuration in which the coil has a predetermined number of turns and includes a helical surface 5i that is substantially continuous from the first turn to the last turn of the coil, and a configuration in which two opposing sides of the four sides of the rectangular cross-sectional shape are included in the helical surface 5i. The stator coil 5 has a recess structure that is recessed from the side facing the outer diameter direction of the stator core 41 to the side facing the direction in which the rotor 3 is located in a part of the coil end portion 5r that is in the direction in which the stator core sheets 41a of the stator core 41 are stacked and is a portion where the stator coil 5 protrudes from the end face of the stator core 41. The recess structure is, for example, a groove portion 5e that is recessed in a groove shape.

As described below, the above-mentioned recessed structure may be a hole 5f (see FIG. 3) that is recessed in a hole shape in a part of the coil end portion 5r from the side facing the outer diameter direction of the stator core 41 to the side facing the direction in which the rotor 3 is located.

When viewed from a direction spanning from the side facing the outer diameter direction of the stator core 41 to the side facing the direction in which the rotor 3 is located, the shape of the groove 5e of the above-mentioned recessed structure appears to be a substantially V-shaped valley cut-out shape, as shown in FIG. 2. The shape of this groove 5e is not limited to a V-shaped valley, but may be a U-shaped valley or other shape, and furthermore, a part of the V-shaped valley, U-shaped valley, or other shape may include an acute angle shape, an arc shape, an obtuse angle shape, a curve, or a straight line, and the shape is not specified.

For example, the structure and shape dimensions of the groove 5e are preferably such that they do not impair the rigidity of the stator coil 5. When the cross-sectional shape of the conductor 5g is substantially rectangular, it is considered that the ratio of the groove 5e to the width dimension of the cross-sectional shape of the conductor 5g is preferably about 1/3. The groove bottom (valley bottom) of the groove 5e may have a valley-shaped groove structure with a curved surface, a U-shaped valley groove structure, or a groove structure with a flat surface.

In order to improve the adhesion of the insulating coating 5b, the cross-sectional shape of the conductor 5g including the portion where the groove 5e is located and the cross-sectional shape of the conductor 5g not including the groove 5e are substantially rectangular. However, it is not preferable for the portions corresponding to the four corners of the rectangular cross-sectional shape of the conductor 5g to have sharp ridgelines, and it is preferable for the tips of the ridgelines to be curved (so-called R-chamfered) or C-chamfered.

In FIG. 2, the groove portion 5e is arranged only on the side of the coil end portion 5r that does not face the teeth and on the outer periphery side of the annular body 5m, but this is not limited thereto. For example, the groove portion 5e may be arranged on the side of the coil end portion 5r that faces the teeth and on the inner periphery side of the annular body 5m. Furthermore, the groove portion 5e may be arranged on both the inner periphery side and the outer periphery side of the annular body 5m.

In the case where the cross-sectional shape of the conductor portion 5g is substantially rectangular, the ratio of the groove portion 5e to the width dimension of the cross-sectional shape of the conductor portion 5g is not limited to about 1/3. Taking into consideration the trade-off between the rigidity of the stator coil 5 and the heat generated by Joule heat due to an increase in the electrical resistance value of the stator coil 5 (temperature increase due to self-heating), the ratio of the groove portion 5e to the width dimension of the cross-sectional shape of the conductor portion 5g is appropriately selected in light of the specifications of the motor.

The number of locations where the grooves 5e are arranged is not particularly limited, and is selected appropriately in consideration of the trade-off between the rigidity of the stator coil 5 and the heat generated by Joule heat (temperature rise due to self-heating) caused by an increase in the electrical resistance of the stator coil 5, and in light of the motor specifications.

In this embodiment, the number of turns in the stator coil 5 is essentially 10. However, this is not particularly limited, and other values may be used. As mentioned above, the number of turns in the stator coil 5 in this embodiment is approximately 9.75, which is slightly less than 10, but is often interpreted as essentially 10.

As described above, the motor 1 of this embodiment includes a stator core 41 including a laminated body in which a plurality of stator core sheets 41a are stacked, a stator 4 including a stator coil 5 in which the teeth 42 of the stator core 41 are part of the magnetic core, and a rotor 3 that is rotatably supported via a gap with the tips of the teeth 42 of the stator core 41. In this motor 1, the stator coil 5 has a conductor portion 5g of the stator coil 5 and a conductor portion 5a including an insulating coating that covers the conductor portion 5g, and the cross-sectional shape of the conductor portion 5g is substantially rectangular and has a predetermined It is a coil with a set number of turns, and includes a substantially continuous spiral surface between the first turn of the stator coil 5 and the last turn of the stator coil 5, and includes two opposing sides of the four sides of the rectangular cross section in the spiral surface, and includes a recessed structure that is recessed from the side facing the outer diameter of the stator core 41 to the side facing the direction in which the rotor 3 is located in a part of the coil end portion 5r that is in the direction in which the stator core 41 is stacked and is the part where the stator coil 5 protrudes beyond the end face of the stator core 41.

As a result, even when the space factor of the stator coil 5 is increased, a stator coil 5 with improved heat dissipation properties against heat generated by eddy currents can be found, making it possible to provide a motor with improved stator coil 5 characteristics compared to conventional motors.

The recessed structure may also be a groove 5e that is recessed in a groove shape in a portion of the coil end portion 5r from the side facing the outer diameter direction of the stator core 41 to the side facing the direction in which the rotor 3 is located.

(Embodiment 2)
3 is a front view of a stator coil 5 according to embodiment 2. The configuration of the motor in this embodiment is similar to that in embodiment 1, and a description of the overlapping contents will be omitted.

In this embodiment, the recessed structure is a hole 5f (see FIG. 3) that is recessed in a portion of the coil end portion 5r from the side facing the outer diameter of the stator core 41 to the side facing the direction in which the rotor 3 is located.

The above-mentioned recessed structure is the shape of the hole 5f when viewed from a direction extending from the side facing the outer diameter direction of the stator core 41 to the side facing the direction in which the rotor 3 is located, and as shown in FIG. 3, it appears as a round hole drilled in a substantially circular shape. The shape of the hole 5f is not limited to a circular hole, but may be an elliptical hole, a square hole, a triangular hole, a polygonal hole, or any other shape. Furthermore, a part of the hole shape may include an acute angle shape, an arc shape, an obtuse angle shape, a curve, a straight line, or the like. The shape of the hole 5f is not specified.

The structure and shape of the holes 5f are preferably such that they do not impair the rigidity of the stator coil 5. When the cross-sectional shape of the conductor portion 5g is substantially rectangular, it is considered that the proportion of the holes 5f relative to the width dimension of the cross-sectional shape of the conductor portion 5g is preferably about 1/3.

In order to improve the adhesion of the insulating coating 5b, the cross-sectional shape of the conductor 5g including the portion where the hole 5f is located and the cross-sectional shape of the conductor 5g not including the hole 5f are substantially rectangular. However, it is not preferable for the portions corresponding to the four corners of the rectangular cross-sectional shape of the conductor 5g to have sharp ridgelines, and it is preferable for the tips of the ridgelines to be curved (so-called R-chamfered) or C-chamfered.

In FIG. 3, the holes 5f are arranged in a row at approximately the center of the coil end portion 5r. However, this is not limited to this. For example, the holes 5f may be arranged in a staggered pattern instead of in a row.

In the case where the cross-sectional shape of the conductor portion 5g is substantially rectangular, the ratio of the hole portion 5f to the width dimension of the cross-sectional shape of the conductor portion 5g is not limited to about 1/3. Considering that there is a trade-off between the rigidity of the stator coil 5 and heat generation due to Joule heat caused by an increase in the electrical resistance value of the stator coil 5 (temperature increase due to self-heating), the ratio of the hole portion 5f to the width dimension of the cross-sectional shape of the conductor portion 5g should be appropriately selected in light of the specifications of the motor.

The number of locations where the grooves 5e are arranged is not particularly limited. The number of locations where the grooves 5e are arranged is appropriately selected in consideration of the trade-off between the rigidity of the stator coil 5 and the heat generated by Joule heat due to an increase in the electrical resistance of the stator coil 5 (temperature increase due to self-heating) and in light of the motor specifications.

In this embodiment, the number of turns in the stator coil 5 is essentially 10. However, this is not particularly limited, and other values may be used. As mentioned above, the number of turns in the stator coil 5 in this embodiment is approximately 9.75, which is slightly less than 10, but is often interpreted as essentially 10.

The stator coil 5 in the present invention can be formed by casting. This method makes it easy to form a spiral stator coil from a conductor with a large cross-sectional area. It is not limited to the above casting, and other methods may be used. For example, it may be formed by cutting a solid material such as copper, aluminum, zinc, magnesium, iron, SUS, or brass. It may also be formed by welding or joining individually formed parts together to form an integrated member.

As described above, in the motor 1 of this embodiment, the recessed structure is a hole 5f that is recessed in a portion of the coil end portion 5r from the side facing the outer diameter direction of the stator core 41 to the side facing the direction in which the rotor 3 is located.

According to the present invention, even when the space factor of the stator coil is increased, a stator coil configuration that improves heat dissipation against heat generated by eddy currents can be found, making it possible to provide a motor with improved stator coil characteristics compared to conventional motors. This is therefore of great industrial value.

REFERENCE SIGNS LIST 1 motor 3 rotor 4 stator 5 stator coil 5a conducting wire portion 5b insulating coating 5c lead-out portion 5d lead-out portion 5e groove portion 5f hole portion 5g conductor portion 5i helical surface 5m ring-shaped body 5q coil wire path portion 5r coil end portion 5s coil corner portion 5t first turn 5u tenth turn 41 stator core 41a stator core sheet 42 teeth 43 slot 44 yoke 45 eddy current 51, 52, 53, 54 busbar A arrow U11, U22, U32, U41, V12, V21, V31, V42, W11, W22, W32, W41 stator coil

Claims (3)

A stator core including a laminate in which a plurality of stator core sheets are laminated;
A motor including a stator including a stator coil having teeth of the stator core as a part of a magnetic core, and a rotor rotatably supported via a gap between the tips of the teeth of the stator core,
The stator coil is
The stator coil has a conductor portion including a conductor portion and an insulating coating covering the conductor portion, and the conductor portion has a substantially rectangular cross-sectional shape,
a coil having a predetermined number of turns, the coil including a substantially continuous helical surface from a first turn of the number of turns of the stator coil to a last turn of the number of turns;
Two opposing sides of the rectangular cross-sectional shape are included in the helical surface,
A motor including a recessed structure that is recessed in the conductor portion in a part of the coil end portion, which is in the stacking direction of the stator core and where the stator coil protrudes beyond the end face of the stator core, from the side facing the outer diameter direction of the stator core to the side facing the direction in which the rotor is located. The motor according to claim 1, wherein the recess structure is a groove portion recessed in a groove shape in a portion of the coil end portion from the side facing the outer diameter direction of the stator core to the side facing the direction in which the rotor is located. The motor according to claim 1, wherein the recess structure is a hole portion that is recessed in a portion of the coil end portion from the side facing the outer diameter direction of the stator core to the side facing the direction in which the rotor is located.