The present invention relates to an electric motor which includes a stator configured by a plurality of iron core divisions.
There has been disclosed in PTL 1 an electric motor which includes a stator configured by a plurality of iron core divisions. A core sheet division described in PTL 1 includes a yoke extending in a circumferential direction, and a tooth extending in a radial direction. A number of the core sheet divisions are laminated in an axial direction to form a core segment. The core segment corresponds to an iron core division according to the present application. The core segment includes at least either a protrusion portion positioned at one end of the yoke in the circumferential direction, or a recess portion positioned at the other end of the yoke in the circumferential direction. A stator iron core is formed by a plurality of the assembled core segments.
In an assembled state of the plurality of core segments, the recess portion included in one of each adjoining pair of the core segments engages with an outer circumference of the protrusion portion included in the other of the corresponding adjoining pair of the core segments in a range wider than 180 degrees.
In addition, an inclined portion is formed at the one end of the yoke in the circumferential direction. A projecting portion is formed at the other end of the yoke in the circumferential direction.
According to this configuration, the plurality of connected core segments are transformed into an annular stator iron core from a serial body configured by the yokes arranged in line. The teeth of the annular stator iron core are extended in the radial direction, and arranged such that the adjoining teeth are positioned in parallel with each other. A coil is wound around the teeth positioned such that the adjoining teeth are positioned in parallel with each other. In a state that the adjoining teeth are positioned in parallel with each other, the coil is easily and continuously wound around the respective teeth.
Moreover, according to this configuration, sufficient clearances are secured between the respective adjoining teeth as passages of a wire forming the coil when the coil is wound around the teeth. In this case, the coil is densely wound around the teeth, thus output of the electric motor disclosed in PTL 1 improves.
There is further disclosed in PTL 2 a stator core division which includes a yoke having S-shaped recess portion and protrusion portion. The stator core division corresponds to an iron core division according to the present application.
PTL 1: Unexamined Japanese Patent Publication No. H10-155248
PTL 2: Unexamined Japanese Patent Publication No. 2011-172353
The present invention is directed to an electric motor including a stator and a rotor.
The stator includes a stator iron core and a coil. The stator iron core includes a plurality of iron core divisions connected to form an annular shape. Each of the iron core divisions includes a yoke and a tooth.
The yoke includes a first end and a second end, and extends in a circumferential direction. The first end includes a protrusion portion positioned on an external diameter side, and a first linear portion positioned on an internal diameter side with respect to the protrusion portion. The first end is positioned at one end in the circumferential direction.
The second end includes a recess portion positioned on the external diameter side, and a second linear portion positioned on the internal diameter side with respect to the recess portion. The second end is positioned at the other end in the circumferential direction. The recess portion includes an external diameter side extension portion positioned on the external diameter side, and an internal diameter side extension portion positioned on the internal diameter side with respect to the external diameter side extension portion.
The tooth crosses the yoke, and extends in a radial direction.
The coil is wound around the stator iron core.
The rotor faces the stator, and is rotatably supported.
The plurality of iron core divisions engage with each other such that the protrusion portion of one of each adjoining pair of the plurality of iron core divisions engages with the recess portion of the other of the corresponding adjoining pair of the plurality of iron core divisions in a manner that the protrusion portion and the recess portion are rotatable. In this case, a rotation center of the protrusion portion is positioned on a bisector of an angle formed by extended and crossed center lines of the teeth of the respective iron core divisions of the corresponding adjoining pair of the plurality of iron core divisions. An internal diameter side extension portion projects toward the one of the corresponding adjoining pair of the plurality of iron core divisions from the bisector.
According to an electric motor configured as described below in an exemplary embodiment of the present invention, in an engagement state between a protrusion portion and a recess portion included in one and the other of each adjoining pair of iron core divisions, respectively, a rotation center of the protrusion portion can be located at a closest possible position to an external diameter side of a yoke. In following description, a portion of engagement between the protrusion portion and the recess portion is also referred to as a connection portion.
According to this configuration, no notch is generated in the yoke in an assembled state of the iron core divisions in an annular shape. In this case, no loss is generated in a coil winding space of a stator included in the electric motor of this exemplary embodiment. In other words, an area occupied by the yoke is reduced to a minimum according to the electric motor of this exemplary embodiment when a comparison is made between stators of the same size. Accordingly, the electric motor of this exemplary embodiment is capable of securing a large coil winding space.
As a result, workability is facilitated in a coil winding step according to the electric motor of the exemplary embodiment of the present invention. Moreover, according to the electric motor of this exemplary embodiment, a sufficient passage is secured for magnetic flux generated from a magnet, as well as the coil winding space is enlarged. Accordingly, further size reduction and improvement of output are achievable according to the electric motor of this exemplary embodiment.
More specifically, a conventional electric motor has following points requiring improvement. According to the electric motor disclosed in PTL 1, the connected core segments are formed into a serial body configured by the yokes arranged in line. Thus, each of the core segments of the electric motor disclosed in PTL 1 includes the projecting portion and the inclined portion. Accordingly, when the connected core segments of the electric motor disclosed in PTL 1 are rounded in an annular shape to configure a stator iron core, a notch is generated in each of the core segments along a passage of magnetic flux. This notch becomes a possible factor for generating an air layer through which the magnetic flux is difficult to pass.
A thickness of the yoke included in each of the core segments of the electric motor disclosed in PTL 1 therefore needs to increase in a radial direction to prevent generation of magnetic saturation in the passage of magnetic flux. Increase in the thickness of the yoke included in each of the core segments generates a loss in the coil winding space. This configuration therefore increases a motor body size of the electric motor disclosed in PTL 1, and results in increase in cost.
Further, according to the electric motor disclosed in PTL 2, the S-shaped recess portion and protrusion portion included in each of the stator core divisions are connected to each other when the stator core divisions are rounded in an annular shape to configure a stator iron core. A clearance is easily generated along a curved portion of contact between the S-shaped recess portion and protrusion portion. The clearance thus generated becomes an air layer through which magnetic flux is difficult to pass. Accordingly, the stator iron core of the electric motor disclosed in PTL 2 is not a core through which magnetic flux easily passes.
The electric motor according to the exemplary embodiment of the present invention is capable of solving the aforementioned problems as points requiring improvement. The electric motor provided herein is an electric motor which reduces cost and increases output without enlarging the size of the electric motor.
Specific exemplary embodiments of the present invention are hereinafter described with reference to the drawings. The exemplary embodiments herein are presented only by way of examples practicing the present invention. Accordingly, a technical scope of the present invention is not limited to the exemplary embodiments described herein.
As illustrated in
In the following description, a circumferential direction refers to an outer circumferential direction of stator iron core 11a having a cylindrical shape. A radial direction refers to a radial direction of stator iron core 11a having the cylindrical shape. An external diameter side refers to an outer circumferential side of stator iron core 11a having the cylindrical shape. An internal diameter side refers to a center point O side of stator iron core 11a having the cylindrical shape.
Stator 11 includes stator iron core 11a and coil 16. Stator iron core 11a has an annular shape formed by a plurality of connected iron core divisions 14. Each of iron core divisions 14 includes yoke 12 and tooth 13. Each of iron core divisions 14 is configured by a plurality of thin steel plates laminated in an axial direction of shaft 22.
As illustrated in
Second end 12b includes recess portion 27 positioned on the external diameter side, and second linear portion 12d positioned on the internal diameter side with respect to recess portion 27. Second end 12b is positioned at the other end in the circumferential direction.
As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
Internal diameter side extension portion 29 projects toward adjoining iron core division 14b from bisector 17.
A configuration which exhibits remarkable advantageous effects is hereinafter described.
As illustrated in
As illustrated in
As illustrated in
Each length h of first linear portion 12c and second linear portion 12d is one third or more of thickness H of yoke 12. It is particularly preferable that length h of first linear portion 12c and second linear portion 12d is a half or more of thickness H of yoke 12.
According to electric motor 10 of the first exemplary embodiment illustrated in
Detailed description further continues with reference to the drawings.
In following description, a portion connecting the adjoining iron core divisions is referred to as a connection portion. As illustrated in
A shape of protrusion portion 26 and a shape of recess portion 27 may be a shape that protrusion portion 26 and recess portion 27 engaging with each other are rotatable. It is preferable that protrusion portion 26 and recess portion 27 configuring connection portion 25 have such a shape not easily generating an air layer even at a time of rotation of connected iron core divisions 14. When protrusion portion 26 and recess portion 27 configuring connection portion 25 have a shape not easily generating an air layer, magnetic flux more easily passes through stator iron core 11a.
According to an example presented hereinbelow, each of protrusion portion 26 and recess portion 27 configuring connection portion 25 has a circular-arc shape. Needless to say, each shape of protrusion portion 26 and recess portion 27 configuring connection portion 25 is not limited to a circular-arc shape.
Rotation center S of each of protrusion portion 26 and recess portion 27 configuring connection portion 25 is located at an arc center of protrusion portion 26. Connection portion 25 is rotatable around rotation center S corresponding to a center of a rotation action. The plurality of iron core divisions 14 are connected to each other via corresponding connection portions 25. Connected iron core divisions 14 are rounded in an annular shape to form a cylindrical shape. The plurality of iron core divisions 14 having a cylindrical shape function as stator iron core 11a. When the plurality of iron core divisions 14 function as stator iron core 11a, protrusion portion 26 and recess portion 27 configuring each of connection portions 25 function as a part of yoke 12 through which magnetic flux passes.
As illustrated in
According to this configuration, yoke 12e included in iron core division 14a and yoke 12f included in iron core division 14b located adjacent to iron core division 14a are arranged in line as illustrated in
Moreover, according to this configuration, a sufficient open space is maintained between end 113a of tooth 13a and end 113b of tooth 13b located adjacent to tooth 13a in the coil winding step. A sufficient clearance thus secured between adjoining teeth 13a and 13b allows a nozzle used as equipment for winding the coil to easily move between adjoining teeth 13a and 13b.
Accordingly, the wound coil reaches a deep portion of each slot 15 in an aligned state. In this case, the coil is densely wound around the stator iron core used in the electric motor according to the first exemplary embodiment. As a result, output from the electric motor is expected to increase according to the first exemplary embodiment.
In addition, internal diameter side extension portion 29 included in recess portion 27 projects toward adjoining iron core division 14b from bisector 17 as illustrated in
More specifically, when rotation center S of protrusion portion 26 is located at a position relatively close to the external diameter side of yoke 12, following advantageous effects are exhibited.
The shape of the plurality of connected iron core divisions 14 is changeable into an annular shape or a serial body by rotation of connection portions 25. In this case, formation of notch 31 is needed to prevent physical interference between external diameter side extension portion 28 included in recess portion 27 and external surface 30 positioned on the external diameter side of yoke 12 including protrusion portion 26, which interference may be caused at a time of a shape change of the plurality of iron core divisions 14 from a serial body into an annular shape. According to the configuration of this exemplary embodiment, a size of notch 31 is allowed to be minimized.
Notch 31 is configured by an air layer through which magnetic flux is difficult to pass. Accordingly, when the size of notch 31 located on the external diameter side with respect to connection portion 25 is minimized, sufficient magnetic flux is allowed to pass through stator iron core 11a. Thus, a thickness of yoke 12 in the radial direction is allowed to decrease to the smallest possible thickness not causing magnetic saturation. In other words, a large space sufficient for winding the coil is secured for stator iron core 11a.
Accordingly, a number of windings of the coil included in the electric motor of the first exemplary embodiment may be increased to a larger number. Alternatively, a thick wire having a lower resistance value may be employed as the coil included in the electric motor of the first exemplary embodiment. As a result, improvement of output and efficiency, or size reduction of the electric motor is achievable according to the first exemplary embodiment.
Moreover, connection portion 25 is formed on the external diameter side of yoke 12 as illustrated in
Accordingly, the electric motor of the first exemplary embodiment reduces an air layer through which magnetic flux is difficult to pass to substantially none between adjoining iron core divisions 14.
Linear portion 32 exhibits following advantageous effects.
Linear portion 32 increases strength of stator iron core 11a assembled in a cylindrical shape. In addition, linear portion 32 increases dimensional accuracy of assembled stator iron core 11a.
Accordingly, the electric motor of the first exemplary embodiment can suppress noise and vibration generated in a case of low dimensional accuracy of assembled stator iron core 11a.
Note that, length h of linear portion 32 described above may be an arbitrary length.
It is preferable, however, that length h of linear portion 32 is longer in consideration of strength of stator iron core 11a, assembly easiness of the stator, easiness of passage of magnetic flux, or other points. It is more preferable that, in particular, length h of linear portion 32 is one third or more of thickness H of yoke 12.
It is particularly preferable that length h of linear portion 32 is a half or more of thickness H of yoke 12.
In addition, angle θ of engagement between protrusion portion 26 and recess portion 27 configuring connection portion 25 is larger than 180 degrees.
According to this configuration, stator iron core 11a configured by the plurality of connected iron core divisions 14 is not disassembled in a step for manufacturing stator 11. Moreover, a special jig is not needed to maintain an in-line state of the plurality of connected iron core divisions 14.
This configuration facilitates work for winding the coil and the like performed for the stator included in the electric motor of the first exemplary embodiment. Accordingly, workability dramatically improves.
Furthermore, according to the above configuration, the plurality of connected iron core divisions are not separated from each other in a step for continuously winding the coil around the different teeth. Thus, a load is not easily applied on a connecting wire included in the coil of the stator used in the electric motor according to the first exemplary embodiment. Accordingly, failure such as disconnection decreases.
Configurations similar to the corresponding configurations of the first exemplary embodiment are given similar reference numbers for reference in following description.
As illustrated in
More specifically, second tip portion 29a is positioned on the adjoining iron core division 14b side with respect to straight line 18 connecting center point O of the stator having an annular shape and rotation center S.
According to the second exemplary embodiment, center point O of the stator corresponds to an axial center of shaft 22.
More specifically, the plurality of iron core divisions 14 are transformed into an annular shape to form stator iron core 11a. In this case, external diameter side extension portion 28 included in recess portion 27 is not positioned on straight line 18 connecting center point O of stator 11 and rotation center S of protrusion portion 26.
According to this configuration, rotation center S of protrusion portion 26 is located at a closest possible position to the external diameter side of yoke 12.
When rotation center S of protrusion portion 26 is located at a closest possible position to the external diameter side of yoke 12, the plurality of connected iron core divisions 14 are rotatable to come into an in-line state.
In addition, the plurality of connected iron core divisions 14 are rounded in an annular shape to configure stator iron core 11a. In this case, formation of notch is not needed for connection portion 25 on the external diameter side of yoke 12.
According to this configuration, the thickness of yoke 12 of the stator iron core used in the electric motor decreases to a minimum so that sufficient magnetic flux can pass through the stator of the second exemplary embodiment. Yoke 12 includes the connection portion not causing magnetic saturation. Accordingly, a large space sufficient for winding the coil is secured in the stator iron core used in the electric motor of the second exemplary embodiment.
Accordingly, a number of windings of the coil included in the stator iron core used in the electric motor of the second exemplary embodiment may be increased to a larger number. Alternatively, a thick wire having a lower resistance value may be employed as the coil for the stator iron core used in the electric motor of the second exemplary embodiment. As a result, improvement of output and efficiency, or size reduction of the electric motor is achievable according to the second exemplary embodiment.
The electric motor presented in the foregoing description is an internal rotor type motor. Needless to say, similar advantageous effects can be exhibited by an external rotor type electric motor according to the present invention.
Note that, in case of the external rotor type electric motor, teeth are formed to extend from yokes toward the external diameter side. However, a relationship between a protrusion portion and a recess portion configuring a connection portion is similar to the corresponding relationship described above.
An electric motor according to the present invention has a wide range of application without any particular limitations as long as a stator is included in the electric motor.
Number | Date | Country | Kind |
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2014-137826 | Jul 2014 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2015/003211 | 6/26/2015 | WO | 00 |