The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2015-101934, filed May 19, 2015, entitled “Axial-Gap Motor-Generator.” The contents of this application are incorporated herein by reference in their entirety.
1. Field
The present disclosure relates to an axial-gap motor-generator.
2. Description of the Related Art
An axial-gap motor-generator that operates as a motor or a generator includes a stator and a rotor that face each other in a rotational axis direction of the rotor, and is therefore advantageous in that it can be thinner than a motor in which a stator and a rotor face each other in a radial direction. Accordingly, axial-gap motor-generators are used as a motor or generator that is required to be thin, such as a generator that is directly and coaxially connected to a crank shaft of an automobile.
For example, Japanese Unexamined Patent Application Publication No. 2008-245356 describes an axial-gap motor-generator including a stator and a pair of rotors. The stator includes coils, and each rotor includes magnets. The rotors face each other with the stator disposed therebetween. Cooling fans are attached to the pair of rotors at the sides that face away from each other. Each cooling fan generates airflows with plate-shaped blades that project from an attachment surface in the rotational axis direction, thereby dissipating heat generated by the coils.
According to one aspect of the present invention, an axial-gap motor-generator that operates as a motor or a generator includes a case, a rotor, and a stator. The rotor is accommodated in and rotatably supported by the case. The rotor includes a magnet. The stator is accommodated in and fixed to the case. The stator includes a coil that faces the magnet in an axial direction of a rotating shaft of the rotor. The case includes a heat-dissipating member that is in contact with the stator, and a portion of the coil is disposed at or near a location where the stator is in contact with the heat-dissipating member.
According to another aspect of the present invention, an axial-gap motor-generator includes a case, a rotor, and a stator. The rotor includes a magnet and is accommodated in the case to be rotatable around a rotating axis of the rotor. The stator is fixed to the case to be accommodated in the case and includes a coil facing the magnet of the rotor in the rotating axis. The case includes a heat-dissipating member with which the coil of the stator is in contact.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.
The embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings.
Embodiments of the present disclosure will be described with reference to the drawings. As illustrated in
The case 4 includes a front lid 12 and a rear lid 14. The case 4 includes a circular portion that overlaps the stator 6 and the rotors 8 in the axial direction in plan view, and a flange portion that is provided outside the circular portion and that has a substantially square outer edge.
The stator 6 and a cooling plate 22 will be described with reference to
The cooling plate 22 has a plurality of radial grooves 26 in both end surfaces that face in the axial direction, the radial grooves 26 extending from the central opening edge 24 to the outer edge. As illustrated in
As illustrated in
The central opening edge 24 of the cooling plate 22 is in contact with the outer periphery of the stator 6 over the entire circumference. The coils 42 are disposed in the region where the stator 6 is in contact with the central opening edge 24, and the end surfaces of the winding portions of the coils 42 are embedded in or exposed on the substrate 40. In the case where the cooling plate 22 is formed of a conductor, such as aluminum, an insulator is disposed between the cooling plate 22 and the end surfaces of the winding portions of the coils 42. The insulator is made of, for example, the resin that forms the substrate 40 or an enamel that covers the winding of the coils 42. The cooling plate 22 covers a part of the wiring portion of each coil 42 at the outer periphery of the stator 6, the part having a width that is about quarter to half the width of the wiring portion.
The rotors 8 will be described with reference to
Each rotor 8 includes a substantially disc-shaped substrate 48 and permanent magnets 50 arranged on the substrate 48 with substantially constant intervals therebetween in the circumferential direction. The substrate 48 has an opening 52, to which the rotating shaft 10 is fitted, at the center, and rotor holes 54 that extend through the substrate 48 in the axial direction in a region on the inner side of the magnets 50 in the radial direction. The outer peripheral edge of the substrate 48 of each rotor 8 is on the inner side of the central opening edge 24 in the cooling plate 22 in the radial direction so that the rotor 8 and the cooling plate 22 do not come into contact with each other.
The magnets 50 are arranged so as to face the coils 42 in the axial direction. The magnets 50 are attached to the substrate 48 so that, at the end surface of the rotor 8 that faces the stator 6, the surfaces of the magnets 50 are closer to the stator 6 than the surface of the substrate 48 is. Accordingly, first airflow generating grooves 56 that extend in the radial direction are defined by side surfaces of the magnets 50 that are adjacent to each other and the surface of the substrate 48. At the end surface of each rotor 8 that does not face the stator 6, second airflow generating grooves 58 are formed in the substrate 48 so as to extend from locations near the rotor holes 54 to the outer peripheral edge in the radial direction. As illustrated in
As illustrated in
The effects of the motor-generator 2 will now be described. The motor-generator 2 operates as a motor or a generator.
Since the cooling plate 22, which has a high thermal conductivity, is in contact with the stator 6 including the coils 42, the heat generated by the coils 42 is transmitted to the cooling plate 22, and the coils 42 are cooled accordingly. The heat transmitted to the cooling plate 22 is dissipated into the air directly or through the case 4. A fluid other than air may instead be brought into contact with the cooling plate 22 or the case 4 as a cooling medium. Since the cooling plate 22 has the radial grooves 26, the cooling plate 22 has a large surface area and easily dissipates heat.
When the rotors 8 are rotated, the first airflow generating grooves 56 and the second airflow generating grooves 58 generate radially outward airflows in the case 4. In the case where the first airflow generating grooves 56 and the second airflow generating grooves 58 extend in the radial direction as illustrated in
Since the stator 6 has the stator holes 44, the surface area thereof is increased. Accordingly, a large amount of heat generated by the coils 42 can be dissipated.
Since the airflows are generated by the first airflow generating grooves 56 and the second airflow generating grooves 58, the size in the axial direction is smaller than that in the case where ribs are provided so as to project from the end surfaces of the rotors 8. Since the first airflow generating grooves 56 are defined by steps between the surface of the substrate 48 and the surfaces of the magnets 50, it is not necessary to increase the thickness of the substrate 48 in the axial direction to form the first airflow generating grooves 56.
A motor-generator 64 according to a second embodiment will now be described with reference to
The case 66 and the cooling plate 68 are substantially circular in plan view. The case 66 includes a front lid 70 and a rear lid 72 that are bonded together by crimping the outer edge portions thereof over the entire circumference or a portion of the circumference. The cooling plate 68 is fixed to the case 66 by being sandwiched between the front lid 70 and the rear lid 72. The cooling plate 68 is similar to that in the first embodiment in that radial grooves 26 are formed therein and in that the cooling plate 68 includes a first plate 68A and a second plate 68B and is in contact with the outer peripheral edge portion of a stator 6.
Each of the front lid 70 and the rear lid 72 has air outlets 74 that extend in the axial direction at locations near the outer edge portion thereof. The airflows generated when the rotors 8 are rotated enter the case 66 through air inlets 20, pass through the spaces between the case 66 and the rotors 8 or through rotor holes 54 and the spaces between the stator 6 and the rotors 8, flow into the flow channels formed by the case 66 and the radial grooves 26, and are then discharged through the air outlets 74.
A motor-generator 76 according to a third embodiment will be described with reference to
Similar to the first embodiment, the case 78 includes a flange portion having a square shape in plan view. However, the case 78 may instead have a circular shape as in the second embodiment. The case 78 includes a front lid 82, a rear lid 84, and the heat-dissipating member 80 that defines an outer peripheral surface of the case 78 and that is sandwiched by the front lid 82 and the rear lid 84. The heat-dissipating member 80 and portions of surfaces of the front lid 82 and the rear lid 84 that sandwich the heat-dissipating member 80, for example, recesses formed in central regions of four sides that form the outer peripheries of the front lid 82 and the rear lid 84, form first vents 86.
The heat-dissipating member 80 includes a first heat-dissipating member 88 that is L-shaped in cross-section and a second heat-dissipating member 90 that is rectangular in cross-section. An L-shaped surface of the first heat-dissipating member 88 and one surface of the second heat-dissipating member 90 form a surface that is angular U-shaped in cross section. The angular U-shaped surface is in contact with an outer peripheral surface of the stator 6 and outer extending portions of both end surfaces of the stator 6 that face in the axial direction. End surfaces of winding portions of coils 42 are embedded in or exposed on a substrate 40 in a region in which the stator 6 is in contact with the heat-dissipating member 80. In the case where the heat-dissipating member 80 is formed of a conductor, such as aluminum, an insulator is disposed between the heat-dissipating member 80 and the end surfaces of the winding portions of the coils 42. The insulator is made of, for example, the resin that forms the substrate 40 or an enamel that covers the winding of the coils 42. The heat-dissipating member 80 covers a part of the wiring portion of each coil 42 at the outer periphery of the stator 6, the part having a width that is about quarter to half the width of the wiring portion.
Bolt holes 18 (see
Similar to the first embodiment, first airflow generating grooves 56 are formed in end surfaces of a pair of rotors 92 that face the stator 6. End surfaces of the pair of rotors 92 that do not face the stator 6 are not provided with structures corresponding to the second airflow generating grooves 58 according to the first embodiment. Instead, second vents 94 having an opening area greater than that of the air inlets 20 according to the first embodiment are formed at positions corresponding to the air inlets 20 according to the first embodiment.
The heat-dissipating member 80 is made of a material having a high thermal conductivity, for example, a metal, such as aluminum, or a ceramic. Therefore, a large amount of heat is transmitted from the coils 42. In addition, since the heat-dissipating member 80 is in contact with the stator 6 over the angular U-shaped region, the contact area between the heat-dissipating member 80 and the coils 42 is large, and the amount of heat dissipated from the coils 42 is increased. The air flows into and out of the case 78 through the first vents 86 and the second vents 94, and flows through the stator holes 44 and the rotor holes 54 in the case 78. Therefore, the dissipation of heat from the coils 42 is accelerated.
Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible. For example, in the third embodiment, the heat-dissipating member may be provided with radial grooves. Alternatively, the radial grooves may be formed in portions of the front lid and the rear lid that are in contact with the cooling plate or the heat-dissipating member instead of the cooling plate or the heat-dissipating member. Instead of arranging a pair of rotors on both sides of the stator, a single rotor may be arranged so as to closely face one end surface of the stator.
According to an aspect of the present disclosure, an axial-gap motor-generator (76) that operates as a motor or a generator includes a case (78); a rotor (92) that is accommodated in and rotatably supported by the case, the rotor including a magnet (50); and a stator (6) that is accommodated in and fixed to the case, the stator including a coil (42) that faces the magnet in an axial direction of a rotating shaft (10) of the rotor. The case includes a heat-dissipating member (80) that is in contact with the stator, and a portion of the coil is disposed at or near a location where the stator is in contact with the heat-dissipating member.
With this structure, since the heat-dissipating member is in contact with the coil or a portion of the stator that is in the vicinity of the coil, a large amount of heat is dissipated from the coil, and the cooling effect is increased. In addition, the heat-dissipating member does not increase the size of the motor-generator in the axial direction as in the case where a cooling fan including blades that project in the above-described is provided.
In the above-described structure, the heat-dissipating member may be in contact with an outer peripheral portion of the stator at which an outer portion of a winding of the coil in a radial direction is disposed.
With this structure, the amount of heat dissipated from the coil to the heat-dissipating member can be increased, and the restriction on the arrangement of the rotor due to the heat-dissipating member can be minimized.
In the above-described structure, the stator may include a disc-shaped substrate (40) to which the coil is attached, and the heat-dissipating member may be in contact with outer peripheral portions of both end surfaces of the stator.
With this structure, the contact area between the heat-dissipating member and the coil can be increased, so that the amount of heat dissipated from the coil can be increased accordingly.
In the above-described structure, the case may further include a front lid (82) and a rear lid (84) that sandwich the heat-dissipating member. First vents (86) that connect a space inside the case to a space outside the case are formed between the front lid and the heat-dissipating member and between the rear lid and the heat-dissipating member, and second vents (94) that connect the space inside the case to the space outside the case are formed in the front lid and the rear lid at positions corresponding to the coil in the axial direction.
With this structure, the amount of heat dissipated from the coil can be increased without changing the size of the motor-generator in the axial direction by increasing the ventilation between the space inside the case and the space outside the space.
In the above-described structure, the stator may include a stator hole (44) that extends through the stator along a coil axis of the coil.
With this structure, the amount of heat dissipated from the coil can be increased by increasing the surface area of the stator including the coil.
In the above-described structure, the rotor may include a rotor hole (54) that extends through the rotor in the axial direction at a location on an inner side of the magnet in a radial direction.
With this structure, the ventilation in the motor-generator is increased, and the amount of heat dissipated from the coil can be increased accordingly.
In the above-described structure, the heat-dissipating member may be made of a metal, and may be disposed adjacent to the coil with an insulator interposed therebetween.
With this structure, the amount of heat transmitted from the coil to the heat-dissipating member made a metal, which has a high thermal conductivity, is increased and cooling of the coil is accelerated.
The present disclosure provides a thin axial-gap motor-generator capable of cooling coils.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
Number | Date | Country | Kind |
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2015-101934 | May 2015 | JP | national |