The present invention relates to an axial gap type rotating electrical machine.
A rotating electrical machine (i.e., a molded motor) in which a stator core is integrally molded from molding resin is per se known (refer to PTL 1). A rotating electrical machine is described in PTL 1 in which a conductive member that electrically connects together a first bracket and a second bracket is buried in a molded body (a molded resin portion).
PTL 1: Japanese Laid-Open Patent Publication No. 2011-67069
With a rotating electrical machine (i.e., a molded motor) in which the stator is covered with an insulating resin such as the rotating electrical machine described in PTL 1, the stator is in an electrically floating state. Due to this, an axial voltage is set up due to the potential difference between the stator and the rotation shaft of the rotor, and, due to the axial current that is thereby created, stray current corrosion may occur in the interior of the bearings.
An axial gap type rotating electrical machine according to a first aspect of the present invention comprises: a rotor that is fixed to a rotation shaft; a stator that is arranged to face the rotor along an axial direction of the rotation shaft; a housing that contains the rotor and the stator; and a resin member for holding the stator to an inner wall of the housing; wherein: the stator comprises a plurality of cores that are arranged in a circumferential direction around the rotation shaft, an insulating bobbin that holds each of the cores, a coil that is wound upon the bobbin, and a first conductive member for shielding electrostatic coupling between the coil and the rotor; the bobbin is formed with an opening portion for housing the core and a flange portion that surrounds the opening portion; and the flange portion is formed with a groove portion in which the first conductive member is housed.
According to the present invention, it is possible to prevent the occurrence of stray current corrosion at the bearings.
In the following, embodiments of axial gap type rotating electrical machines according to the present invention (which are axial gap type motors) will be explained with reference to the drawings.
This axial gap type rotating electrical machine (hereinafter simply termed the “rotating electrical machine 100”) comprises the rotation shaft 188, a pair of rotors 150 that are fixed to the rotation shaft 188, a stator 120 that is disposed between the pair of rotors 150, and the housing 180 that houses the pair of rotors 150 and the stator 120. The rotating electrical machine 100 of this embodiment is an axial gap type rotating electrical machine of the two rotor one stator type, having a construction in which the stator 120 is sandwiched between the pair of rotors 150 with predetermined gaps being left therebetween, and, because it can obtain higher magnetic flux, is superior as compared with a one rotor one stator axial gap type rotating electrical machine from the standpoints that the efficiency and the specific power can be increased.
The pair of rotors 150 are arranged to face one another along the axial direction with a predetermined gap being left between them. Since both the pair of rotors 150 are formed to have similar shapes, only one of these rotors 150 will be explained as a representative. The rotor 150 is provided with an axial hole through which the rotation shaft 188 passes. Due to the rotation shaft 188 being inserted into this axial hole and being fixed therein, the rotor 150 and the rotation shaft 188 are formed into an integrated body.
The rotor 150 comprises a casing member 151 that is approximately formed as a circular plate and a plurality of magnets 152. Concave portions 151a into which the magnets 152 are fitted are provided to the casing member 151, arranged along the circumferential direction of the rotation shaft 188 (hereinafter this will simply be termed the “circumferential direction”). The magnets 152 are disposed in the concave portions 151a at regular intervals along the circumferential direction. Each of the magnets 152 is magnetized along the axial direction, so that one side thereof becomes an S pole while the other side thereof becomes an N pole. And the magnets 152 are arranged along the circumferential direction so that their neighboring magnetic poles have opposite polarities, in other words so that their polarities are N, S, N, S, . . . .
As seen along the axial direction, each one of the magnets 152 in one of the pair of rotors 150 and a corresponding magnet 152 in the other rotor 150 are positioned at the same position in the circumferential direction, and moreover have the same shape. Neodymium-based or samarium-based sintered magnets, ferrite magnets, or neodymium-based bonded magnets may be employed for the magnets 152.
The stator 120 is arranged to face the rotors 150 along the axial direction. As shown in
As shown in
The housing 180 is made from an electrically conductive metallic material. This housing 180 comprises the cylindrical center housing 182, which is provided with heat dissipation fins, and a pair of housing end members 181 that close apertures at both ends of the center housing 182. The space surrounded by the center housing 182 and the pair of housing end members 181 constitutes a housing space that houses the pair of rotors 150 and the stator 120. The housing end members 181 are provided with through holes through which the rotation shaft 188 passes and with bearing support portions 181a that support bearings 186. The rotation shaft 188 is supported by the bearings 186 so as to be rotatable.
In the following explanation, for convenience, as shown in
In each one of the plurality of cores 121 that are arranged in the circumferential direction as shown in
As shown in
As shown in
As shown in
Radially outward end portions 161e, 162e of the conductive bars 161, 162 are sandwiched between an inner circumferential portion 132 of the conductive ring 130 that will be described hereinafter and a flange portion 112 of the bobbin 110, and thereby the conductive bars 161, 162 and the conductive ring 130 are electrically and mechanically connected together. It should be understood that, as shown by the schematic cross sectional figure in
The length of the core 121 in the axial direction is longer than the length of the bobbin 110 in the axial direction, and thus the two end portions of the core 121 in the axial direction project by predetermined distances from the openings at both ends of the barrel portion 111. In the following, the two end portions of the core 121 that project from the bobbin 110 will both be termed “projecting end portions 121e”. Due to this, with the exception of the projecting end portions 121e, the inner surface 121i of the core 121, its outer surface 121o, and its pair of side surfaces 121s are covered by the barrel portion 111, while the inner surfaces 121i of the projecting end portions 121e, their outer surfaces 121o, their pairs of side surfaces 121s, and also their end surfaces 121t are exposed.
As shown in
As shown in
As shown in
As shown in
Fitting holes 135 are provided in the base portion 133, with the pins 115 described above that are provided in the bobbin 110 being fitted thereinto. And a cutaway portion 138 is provided in the base portion 133, with the takeout portion 119 described above that is provided upon the bobbin 110 being disposed therein.
A plurality of slits 134 are provided in the inner circumferential portion 132 of the base portion 133, extending radially outward from its internal circumferential edge surface and spaced in sequence in its circumferential direction. To put this in another manner, a plurality of prongs 132a are provided as extending from the outer circumferential portion 131 in the radially inward direction and spaced along the circumferential direction. The shapes of the plurality of slits 134 are set by taking into account the positional relationship with the fitting holes 135, so that the fitting holes 135 and the slits 134 do not interfere with one another.
The projecting portions 136 are provided to project radially inwards, so that they extend from the base portion 133 along the radially inward direction. And slots 139 are provided in the projecting portions 136, extending in the radially outward direction from the ends of the projecting portions 136. To put this in another way, each projecting portion 136 is divided into two projecting prongs 137 by the slot 139, and is thus formed in bifurcated shapes.
A method for manufacturing this rotating electrical machine 100 will now be explained.
In the preparatory process S100, the various components that make up the rotating electrical machine 100 are prepared: for example, the center housing 182, the housing end members 181, the thin magnetic plates 121a that make up the core 121, the rotors 150, and so on are prepared. And the rotation shaft 188 is installed into one of the pair of rotors 150.
In the process S110 for manufacturing the conductive rings, the conductive rings 130 are formed by performing pressing processing upon a plate shaped member that is made from an electrically conductive metallic material.
In the core manufacturing process S120, each of the cores 121 is manufactured by stacking together a predetermined number of elongated rectangular plates of amorphous foil strip that are made from an iron-based amorphous metal, then are pressed from both sides in the direction in which they are stacked, and then are subjected to cutting processing so as to be formed, approximately, into a trapezoidal prism.
In the bobbin installation process S130, the cores 121 that have been made in the core manufacturing process S120 are press-fitted into the opening portions of the barrel portions 111 of the bobbins 110. Both end portions of each of the cores 121 are projected from the two ends of the barrel portion of the corresponding bobbin 110. The end surfaces 121t that constitute the two end surfaces of the core 121 are set to positions at a predetermined distance from the flange portions of the bobbin 110. And the conductive bars 161, 162 are fitted into the groove portions 118 of the flange portions 112.
In the coil winding process S140, each of the coils 122 is formed by winding a predetermined number of turns of conductive wire having an insulation coating upon the barrel portion 111 of the corresponding bobbin 110. In other words, the coil 122 is installed upon the core 121 via the bobbin 110. And the lead wire of the coil 122 is disposed in the opening of the takeout portion 119 that is provided in the flange portion 112 of the bobbin 110.
In the positioning process S150, the cores 121, the two conductive rings 130, and the center housing 182 are arranged in their predetermined positions. As shown in
In the process S151 of positioning one of the pair of conductive rings 130 (this one hereinafter will be referred to as the lower conductive ring 130L), as shown in
In the core positioning process S153 (refer to
In the center housing positioning process S155 (refer to
In the process S157 of positioning the other of the pair of conductive rings 130 (this one will hereinafter be referred to as the upper conductive ring 130U) (refer to
It should be understood that it is simple and easy to perform positioning of the upper conductive ring 130U with respect to the cores 121 by fitting the pins 115 of the bobbins 110 into the fitting holes 135 of the upper conductive ring 130U. The upper conductive ring 130U is positioned in the axial direction with respect to the center housing 182 by contacting the upper conductive ring 130U against the upper support projection 183U of the center housing 182.
The base portion 133 of the upper conductive ring 130U is contacted against the inner surface of the center housing 182. In concrete terms, the external peripheral side surface of the circular annular base portion 133 is contacted against the inner peripheral surface of the center housing 182, and the lower surface of the base portion 133 is contacted against the upper surface of the upper support projection 183U.
In the bending process S160 (refer to
As shown in
Forces of the same order act from the bending tool 196, both on the position P1 upon the support prong 137b, and on the position P2 upon the bent prong 137a. The magnitude relationship between the length from the base end portion of the support prong 137b to the position P1 that is the point of operation on the support prong 137b, in other words the length L1 of this moment arm, and the length from the base end portion of the bent prong 137a to the point P2 on the bent prong 137a, in other words the length L2 of this moment arm, is that L2>L1. Accordingly, the bending moment that acts upon the bent prong 137a is greater than the bending moment that acts upon the support prong 137b. Due to this, it is possible for the support prong 137b not to be deformed, while the bent prong 137a is bent toward the side surface 121s of the core 121. It should be understood that while, in this embodiment, the support prong 137b has a projecting length that is approximately the same as that of the bent prong 137a, it will be sufficient if the length of the support prong 137b is adequate to support the one end of the bending tool 196 at the point P1 while the bent prong 137a is being bent.
As shown in
In the molding process S170 (refer to
The upper mold 193, which constitutes an upper die, can be raised and lowered in the vertical direction, and comprises a main block 193a, a first circular cylindrical portion 193b that extends vertically from the main block 193a, and a second circular cylindrical portion 193c that extends vertically from the first circular cylindrical portion 193b. The diameter of the first circular cylindrical portion 193b is the same as the diameter of the first circular cylindrical portion 191b of the lower mold 191. In other words, the diameter of the first circular cylindrical portion 193b of the upper mold 193 is set to have approximately the same dimension as the internal diameter of the center housing 182. And the diameter of the second circular cylindrical portion 193c is the same as the diameter of the second circular cylindrical portion 191c of the lower mold 191. In other words, the diameter of the second circular cylindrical portion 193c of the upper mold 193 is set to be slightly larger than the diameter of the rotation shaft 188. The lower surfaces of the first circular cylindrical portion 193b, the second circular cylindrical portion 193c, and the main block 193a are formed as flat surfaces.
When the upper mold 193 is lowered to a predetermined position, the outer circumferential portion 131 of the base portion 133 of the upper conductive ring 130U and the end surfaces 121t of the cores 121 are contacted against the lower surface of the first circular cylindrical portion 193b. And the upper end surface of the center housing 182 is contacted against the lower surface of the main block 193a. Moreover, the lower surface of the second circular cylindrical portion 193c is disposed to face the upper surface of the second circular cylindrical portion 191c of the lower mold 191. A predetermined gap is created between the second circular cylindrical portion 193c of the upper mold 193 and the second circular cylindrical portion 191c of the lower mold 191, and this constitutes a flow conduit for resin to pass through.
Resin having good fluidity and good insulating characteristic is injected from an injection hole 193h that is provided in the upper mold 193 into a space S for resin charging that is surrounded by the lower mold 191, the upper mold 193, and the center housing 182, so that resin is charged into this space S. Thereafter, when the resin has hardened, the molded body 140 shown in
As shown in
In the rotor assembly process S180 (refer to
In the lead connection process S190 (refer to
For each of the plurality of coils 122 that are the coils for the U phase, one end thereof is connected to the U phase lead connection ring, while the other end thereof is connected to the neutral point lead connection ring. And for each of the plurality of coils 122 that are the coils for the V phase, one end thereof is connected to the V phase lead connection ring, while the other end thereof is connected to the neutral point lead connection ring. Moreover, for each of the plurality of coils 122 that are the coils for the W phase, one end thereof is connected to the W phase lead connection ring, while the other end thereof is connected to the neutral point lead connection ring. It should be understood that the positions where the lead connection rings are installed are not limited to being located between the rotors 150 and the housing end members 181. For example, it would be acceptable to dispose the neutral point lead connection ring above the flange portions 112 of the bobbins 110. In this case, the process of connecting the lead wires of the coils 122 to this neutral point lead connection ring would be performed during the positioning process S150, or the like.
In the closing process S195 (refer to
The stator 120 of the rotating electrical machine 100 that has been manufactured in this manner comprises the plurality of cores 121 that are disposed in the circumferential direction of the rotation shaft 188, the bobbins 110 that hold the cores 121, the coils 122 that are wound upon the bobbins 110, the conductive bars 161, 162 for shielding electrostatic coupling between the coils 122 and the rotors 150, and the conductive rings 130 that electrically connect together the side surfaces 121s, which are the end surfaces of the cores 121 in the circumferential direction, and the housing 180.
According to the first embodiment of the present invention described above, the following advantageous operational effects may be obtained.
(1) The cores 121 and the housing 180 are electrically connected together by the conductive rings 130. Accordingly, the cores 121 are grounded to the housing 180, so that it is possible to prevent the cores 121 from developing floating potential. And moreover it is possible to keep the stator 120, the housing 180, and the rotation shaft 188 of the rotors 150 that is held in the housing 180 via the bearings 186 that are provided to the housing 180 all at the same electrical potential, so that it is possible to prevent the development of stray current corrosion of the bearings 186.
(2) The conductive bars 161, 162 are received in the groove portions 118 of the flange portions 112. Due to this, electrostatic coupling of common mode voltage from the coils 122 to the rotors 150 is shielded by the conductive bars 161, 162. As a result, the induction of common mode voltage in the rotors 150 is reduced and the voltage that is applied between the inner rings and the outer rings of the bearings 186 that support the rotors 150 is reduced, so that development of stray current corrosion of the bearings 186 is effectively suppressed.
Moreover, by the conductive bars 161, 162 being received in the groove portions 118, it is possible to perform positioning thereof between the rotors 150 and the coils 122 in predetermined positions in a simple and easy manner.
And, since the conductive bars 161, 162 are received in the groove portions 118, accordingly deviation of the positions of the conductive bars 161, 162 is prevented, even if formation pressure acts upon the conductive bars 161, 162 during the molding process. As a result, it is possible to fix the conductive bars 161, 162 in their predetermined positions, so that it is possible for shielding to be reliably performed by the conductive bars 161, 162.
(3) The conductive bars 161, 162 are sandwiched between the flange portions 112 of the bobbins 110 and the conductive rings 130. Due to this, it is possible to prevent positional deviation of the conductive bars 161, 162 more reliably. Moreover, since there is electrical continuity between the conductive bars 161, 162 and the housing 180 via the conductive rings 130, accordingly the conductive bars 161, 162 are grounded to the housing 180, and it is possible to prevent the conductive bars 161, 162 from developing floating potential.
(4) The cores 121 are made of pluralities of thin magnetic plates 121a laminated together in the radial direction of the rotation shaft 188. And the conductive rings 130 are electrically connected to the housing 180 and to the side surfaces 121s of the cores 121, in other words to the end surfaces of the cores 121 in the circumferential direction. Due to this, there is no influence by the radial dimensions of the cores 121 that are made by laminating together the thin magnetic plates 121a in the radial direction, in other words by the dimensional accuracy in the direction of lamination.
For example, in a case in which the housing 180 and the outer surfaces 121o of the cores 121 are electrically connected together by conductive members, if the dimension of one of the cores 121 in the radial direction is a little shorter than its design value, then the corresponding conductive member and that core 121 may not contact one another.
Contrariwise, in such a case in which the housing 180 and the outer surfaces 121o of the cores 121 are electrically connected together by conductive members, if the dimension of one of the cores 121 in the radial direction is a little longer than its design value, then the corresponding conductive member may be pinched and compressed between the core 121 and the housing 180, so that the conductive member may be deformed.
Due to this, if the housing 180 and the outer surfaces 121o of the cores 121 are to be electrically connected together by conductive members, it is necessary to regulate the dimensional tolerances between the outer surfaces 121o of the cores 121 and the inner surface of the housing 180 minutely, and similarly it is necessary to regulate the dimensional tolerance of the direction of lamination of the cores 121 minutely.
In particular, in this embodiment, the thin magnetic plates 121a of which the cores 121 are composed are made from amorphous foil strip, and their thickness (for example around 0.3 mm) is thin as compared to the thickness of magnetic steel sheet (for example around 0.5 mm), so that the number of laminations becomes great as compared to what would be the case if magnetic steel sheet were employed. As a result, if the cores 121 are formed from thin magnetic plates 121a made from an amorphous metallic material, then, due to the fact that the dimensional tolerance increases cumulatively, uneven variation of the dimension in the direction of lamination, in other words of the dimension in the radial direction, can easily occur, as compared to the case of a core that is made as a lamination of magnetic steel sheets.
However since, in this embodiment, it is arranged to contact the projecting portions 136 of the conductive rings 130 to the end surfaces of the cores 121 in the circumferential direction, accordingly there is no influence by the dimensional accuracy of dimensions of the cores 121 in the radial direction. According to this embodiment, no undesirable forces act upon the conductive rings 130, so that it is possible reliably electrically to connect together the housing 180 and the cores 121. And, since the dimensional tolerances are relaxed as compared to the case in which the outer surfaces 121o of the cores 121 are contacted against conductive members, accordingly the manufacture is simple and easy.
(5) The slots 139 are provided in the projecting portions 136 and extend from the ends of the projecting portions 136 in directions radially outward from the rotation shaft 188. Due to this, it is possible to bend the bent prongs 137a of the projecting portions 136 simply and easily by inserting the bending tool 196 into the slots 139 and by rotating it, so that it is possible to anticipate enhancement of the working efficiency.
(6) The pair of pins 115 for positioning are provided upon the flange portion 112 of the bobbin 110, and the pair of fitting holes 135 into which these pins 115 are inserted are provided upon the conductive ring 130. By fitting the pins 115 into the fitting holes 135, it is simple and easy to perform positioning of the conductive ring 130. And accordingly, due to the workability being enhanced, it is possible to anticipate that the man-hours required for manufacture will be reduced.
(7) Since the pair of pins 115 and the pair of fitting holes 135 are engaged together, accordingly the occurrence of positional deviation or deformation of the conductive ring 130 when the bending tool 196 is rotated can be prevented, and it is possible to enhance the workability for bending the bent prong 137a.
(8) The thin magnetic plates 121a that make up the cores 121 are made from an amorphous metallic material. Due to this, it is possible to reduce the energy losses (i.e. the losses due to hysteresis), as compared to the case of cores 121 that are made from, for example, magnetic steel sheet.
As described above, the thickness of the thin magnetic plates 121a that make up the cores 121 (for example 0.3 mm) is thinner, as compared to the thickness of magnetic steel sheet (for example 0.5 mm). Due to this, as compared to cores made from magnetic steel sheet, the cores 121 of this embodiment can easily be deformed when force acts upon their side surfaces 121s. Because of this, it is possible for the bent prongs 137a to bite into the side surfaces 121s of the cores 121 during the bending process S160. And since, as a result, it is possible to enhance the strength of the connections and moreover to increase the contact areas between the bent prongs 137a and the cores 121, accordingly it is possible to reduce the electrical resistance.
(9) Since the conductive rings 130 contact both the cores 121 and the center housing 182, accordingly heat generated in the cores 121 is transmitted to the center housing 182 via the conductive rings 130 And this heat that has been transmitted to the center housing 182 is dissipated to the external atmosphere. In other words, the conductive rings 130 also serve the function of transmitting heat from the cores 121 to the housing 180, so that it is possible to anticipate enhancement of the performance for cooling.
It should be understood that, since this heat is transmitted to the housing 180 by the conductive rings 130 with good efficiency, accordingly it will be effective to make the volumes of the conductive rings 130 great, in other words to make their thermal capacities great. However, if their volumes become great, the losses due to eddy currents also become great. Thus, in this embodiment, it is possible to reduce the losses due to eddy currents by changing the thickness of the base portions 133 as in (10) through (12) below and by forming the plurality of slits 134, and accordingly enhancement of the efficiency of this motor may be anticipated.
(10) Since the inner circumferential portions 132 of the conductive rings 130 are closer to the cores 121 as compared to their outer circumferential portions 131, accordingly the influence of eddy currents upon them is greater. Thus, in this embodiment, since the thickness of the inner circumferential portions 132 (for example around 1 mm) of the conductive rings 130 is thinner than the thickness of the outer circumferential portions 131 (for example around 3 mm), accordingly it is possible to reduce losses due to eddy currents in the inner circumferential portions 132.
(11) The plurality of slits 134 are provided in the inner circumferential portions 132 of the base portions 133 so as to extend outward in the radial direction from their inner circumferential edge. Since the paths of eddy currents are intercepted by these slits 134, accordingly it is possible to reduce losses due to eddy currents, as compared to the case when these slits 134 are not provided.
(12) The slots 139 are provided in the projecting portions 136. Since the paths of eddy currents are intercepted by these slots 139, accordingly it is possible to reduce the losses due to eddy currents, as compared to a case in which no such slots 139 are provided.
(13) Since the outer circumferential portions 131 of the conductive rings 130 are remote from the cores 121 as compared to their inner circumferential portions 132, accordingly the influence of eddy currents therein is small. In this embodiment, as described above, by contrast to the thickness of the inner circumferential portions 132 of the conductive rings 130 (for example around 1 mm), the thickness of the outer circumferential portions 131 is thicker (for example around 3 mm), so that the rigidity of the conductive rings 130 is enhanced. In other words, in this embodiment, the rigidity is enhanced while suppressing increase of the eddy current losses. Due to this, it is possible to prevent deformation of the conductive rings 130 due to clamping force from the main housing 182 acting upon the conductive rings 130 by the conductive rings 130 being pressed into the main housing 182. Furthermore, it is possible to prevent deformation of the base portions 133 when bending the bent prongs 137a with the bending tool 196. It should be understood that the thickness of the bent prongs 137a is the same as the thickness of the inner circumferential portions 132, so that it is possible to bend and deform the bent prongs 137a simply and easily, and the workability is good.
(14) The plurality of cores 121 are integrally molded with an insulating resin, so that the side surfaces 121s of the cores 121, which are their end surfaces in the circumferential direction, are covered along with the projecting portions 136 of the conductive rings 130. The cores 121 can be held with the molded body 140, and moreover it is possible to maintain the connection strength at the electrical connection portions between the cores 121 and the conductive rings 130. As a result, it is possible to provide a rotating electrical machine 100 that is excellent from the standpoints of anti-vibration performance and anti-shock performance.
(15) In the conductive rings 130, the circular annular base portions 133 that contact the inner surface of the housing 180 are formed integrally with the plurality of projecting portions 136 that project from those base portions 133 toward the center of the rotation shaft 188. Due to this, during the positioning process S150, relative positioning of the cores 121 can be performed simply and easily, while preventing the cores 121 from positional deviation in the axial direction and preventing them from tilting. In other words, it is possible to enhance the workability of arranging the conductive rings 130 and the cores 121, as compared to a case in which a plurality of conductive members must be arranged.
An axial gap type rotating electrical machine according to a second embodiment of the present invention (hereinafter simply termed the “rotating electrical machine 200”) will now be explained with reference to
This rotating electrical machine 200 according to the second embodiment has a similar structure to the rotating electrical machine 100 explained in connection with the first embodiment, except for the structure of the conductive members 230. In the conductive rings 130 of the first embodiment, which were the conductive members thereof, the circular annular base portions 133 were formed integrally with the plurality of projecting portions 136 that projected from those base portions 133 (refer to
As shown in
The base portion 233 of the conductive member 230 is contacted against the inner surface of the center housing 182, and the bent prong 137a of the projecting portion 136 is bent with the bending tool 196 (refer to
According to this second embodiment, in addition to the advantageous operational effects (1) through (15) explained above in connection with the first embodiment, the following further advantageous operational effect is obtained.
(16) The approximately circular annular conductive ring 130 is divided around the circumferential direction, so as to form the plurality of conductive members 230. Since in this second embodiment it is possible to intercept the paths of eddy currents by the surfaces of separation in this manner, accordingly it is possible further to reduce the losses originating in eddy currents, as compared to the approximately circular annular conductive ring 130 explained in connection with the first embodiment. It should be understood that the number of divisions is not limited to the case of corresponding to the number of the cores 121.
An axial gap type rotating electrical machine according to a third embodiment of the present invention will now be explained with reference to
In the first embodiment, an example was explained in which the end surfaces 121t of the cores 121 were not covered over by the molded body 140, but were exposed. However, if ferrite magnets are employed as the magnets 152 that are installed to the rotors 150 of an axial gap type rotating electrical machine, then it is necessary to increase the diameters of the rotors 150, since the magnetic characteristics are inferior as compared with the case of employing rare earth magnets. As a result, the sizes and the weights of the cores 121 are increased so that it is necessary to enhance the strength with which the stator cores 121 are held. Accordingly, in this third embodiment, the end surfaces 121t of the cores 121 are covered by the molded body 340, so that the strength with which the cores 121 are held is increased.
As a technique for enhancing this holding strength, for example, there is the technique described in Japanese Laid-Open Patent Publication No. 2007-28855 (hereinafter this will be termed the “prior art technique”). In this prior art technique, letter-T shaped cores are inserted into the stator core yokes, these cores are projected from the stator core yokes, and the entire projecting portions are covered with resin. With this prior art technique, convex portions extending in the radial direction are formed on surfaces of the cores that oppose the rotor, and the strength with which the cores are held is increased by covering the cores with resin except for the convex portions. However, the provision of these convex portions upon the cores leads to increase of the number of manufacturing steps, and accordingly is not desirable. Moreover there is also the problem that, if the cores are made by laminating together thin magnetic plates made from amorphous foil strip, then it is difficult to form the convex portions.
The rotating electrical machine according to the third embodiment has a similar structure to the rotating electrical machine of the first embodiment, but the number of the cores 121 and the shapes and dimensions of the structural members are different. In detail, this rotating electrical machine 300 comprises a rotation shaft (not shown in the figures), a pair of rotors 150 that are fixed to the rotation shaft, a stator 120 that is disposed between the pair of rotors 150, and a housing that houses the pair of rotors 150 and the stator 120 (only the center housing 182 is shown in
In this third embodiment, before the molding process, the plurality of cores 121 are held in predetermined positions within the center housing 182 by a holding member 397.
The holding member 397 is attached by being pressed into the center housing 182 of the housing 180 or by being adhered thereto, so that the external circumferential portion 398 of the holding member 397 is adhered to the inner peripheral surface of the center housing 182. And a plurality of the sandwiching portions 399 are provided at predetermined intervals along the circumferential direction. An opening portion 399a is provided between two sandwiching portions 399 adjacent to one another in the circumferential direction, into which a core 121 and its bobbin (not shown in the figures) are pressed. Although this feature is not shown in the figures, it should be understood that a plurality of through holes are provided in the external circumferential portion 398 of the holding member 397, and these through holes extend in the axial direction, thus constituting flow conduits for the resin in the fluid state during molding.
The coils 122 are wound above and below the sandwiching portions 399 so as to avoid the sandwiching portions 399. Each of the cores 121 is attached by being pressed into one of the opening portions 399a, and is sandwiched by a pair of sandwiching portions 399 that are adjacent in the circumferential direction. It should be understood that, in this embodiment, in order for the cores to be pressed into the opening portions 399a, the holding member 397 is made from a resin material that has moderate flexibility and is elastically deformable, and the difference between the length of the upper base and the length of the lower base in the trapezoidal cross section of the approximately trapezoidal prism shaped cores 121 is set to be small. Moreover, it should be understood that it would also be acceptable to arrange for the cores 121 to be approximately shaped as rectangular parallelepipeds, instead of being approximately shaped as trapezoidal prisms.
As shown in
By contrast, in this third embodiment, the resin is charged after a lower mold 391 and an upper mold 393 have been arranged in predetermined positions in the following manner.
As shown in
The upper mold 393 can be raised and lowered in the vertical direction, and comprises a main block 393a, a first circular cylindrical portion 393b that extends vertically from the main block 393a, and a second circular cylindrical portion 393c that extends vertically from the first circular cylindrical portion 393b. The diameter of the first circular cylindrical portion 393b is the same as the diameter of the first circular cylindrical portion 391b of the lower mold 391. In other words, the diameter of the first circular cylindrical portion 393b of the upper mold 393 is set to have approximately the same dimension as the internal diameter of the center housing 382. And the diameter of the second circular cylindrical portion 393c is the same as the diameter of the second circular cylindrical portion 391c of the lower mold 391. In other words, the diameter of the second circular cylindrical portion 393c of the upper mold 393 is set to be slightly larger than the diameter of the rotation shaft 188. The lower surfaces of the first circular cylindrical portion 393b, the second circular cylindrical portion 393c, and the main block 393a are formed as flat surfaces.
The holding member 397 is adhered to the center housing 182 in advance, and the cores 121 are installed into the holding member 397. Then the opening at the bottom end of the center housing 182 is fitted over the first circular cylindrical portion 391b, so that one end surface of the center housing 182 is contacted against the upper surface of the main block 391a. A gap is created between the upper surface of the first circular cylindrical portion 391b of the lower mold 391 and the lower end surfaces 121t of the cores 121. Then, when the upper mold 393 is lowered down to a predetermined position, the lower surface of its second circular cylindrical portion 393c contacts against the upper surface of the second circular cylindrical portion 391c of the lower mold 391. And a gap is created between the lower surface of the first circular cylindrical portion 393b of the upper mold 393 and the upper end surfaces 121t of the cores 121.
Insulating resin having good fluidity is injected from an injection hole 393h that is provided in the upper mold 393 into a space S for resin charging that is surrounded by the lower mold 391, the upper mold 393, and the main housing 182, and thereby this resin is charged into the space S. Thereafter, when the resin has hardened, a molded body 340 shown in
According to this third embodiment, in addition to advantageous operational effects similar to those explained above in connection with the first embodiment being obtained, also the following further advantageous operational effects are obtained.
(17) It is arranged to cover over the entire outer surfaces of the projecting end portions 121e of the cores 121 that project from the bobbins 110 with the molded body 340, in other words to cover over their end surfaces 121t and their pairs of side surfaces 121s, their inner surfaces 121i, and their outer surfaces 121o. Due to this, as compared to the case with the first embodiment, it is possible to improve the strength with which the cores 121 are held, and thus it is possible to provide a rotating electrical machine that is excellent from the standpoints of anti-vibration resistance and anti-shock resistance.
Furthermore, it is also possible to prevent the cores 121 from undergoing oxidization reactions due to moisture included in the air within the housing 180. In other words, since it is possible to prevent the generation of rust upon the cores 121, accordingly it is possible to provide a rotating electrical machine that is capable of maintaining its performance as a motor over the long term.
(18) As compared to magnetic steel sheet or the like, the thickness of amorphous foil strip is thinner, and it is harder, which makes it difficult to employ amorphous foil strip for the thin magnetic plates 121a if the core is to be made in a complicated shape as in the prior art. By contrast, the cores 121 can be manufactured simply and easily in this embodiment, since it is possible to form their end surfaces 121t and their side surfaces 121s as simple plane surfaces so as to define the cores 121 as trapezoidal prisms.
(19) It is arranged to cover both the upper projecting end portions 121e and also the lower projecting end portions 121e of the cores 121 with the molded body 340. In other words, since both the end portions in the axial direction of the cores 121 are held by the molded body 340, accordingly it is possible to enhance the strength with which the cores 121 are held, as compared with a case in which only their one end portions are held by the molded body 340.
(20) Since it is possible to enhance the strength with which the cores 121 are held, accordingly it is possible to employ ferrite magnets for the magnets 152 that are installed to the rotor 150. Since, as compared to other magnetic materials, ferrite magnets can be obtained more cheaply and moreover their availability is more stable, accordingly it is possible to anticipate reduction in the cost of the rotating electrical machine 100.
The third embodiment can also be implemented in the following variant manner.
And, as shown in
As shown in
In this manner, in this variant of the third embodiment, the die contacting region 421d against which the protruding contact portion 494 of the mold is contacted is provided upon each one of the pair of end surfaces 121t. The die contacting regions 421d of each pair of end surfaces 121t are provided in the same position as seen along the axial direction, and moreover are set to be of the same shape. And each of the die contacting regions 421d on each pair of end surfaces 121t is at least set to be upon the same vertical line. For this, during the molding process, each protruding contact portion 494 of the upper mold 493 and the corresponding protruding contact portion 494 of the lower mold 491 are arranged so as mutually to face one another along the same vertical line.
Due to this, it is possible to prevent positional deviation such as tilting of the cores 121 occurring during the molding process, since the cores 121 are sandwiched between the protruding contact portions 494 of the upper mold 493 and the corresponding protruding contact portions 494 of the lower mold 491, along the same vertical lines. And, since it is possible to hold the cores 121 in their proper positions with the molded body 440, accordingly it is possible to provide a rotating electrical machine whose efficiency as a motor is excellent.
Since it is possible to hold the cores 121 with the upper mold 493 and the lower mold 491, accordingly it is possible to omit the holding member 397 that were explained above in connection with the third embodiment.
The following variations are also included within the scope of the present invention, and moreover it is also possible to combine one or more of these variant embodiments with one or more of the embodiments described above.
(1) It would also be acceptable to arrange for the prongs 132a that are provided on the base portion 133 facing the outer surfaces of the cores 121 (refer to
(2) While, in the embodiments described above, examples were explained in which the slots 139 were provided in the projecting portions 136, the present invention should not be considered as being limited to that structure. It would also be acceptable to press projecting portions 136 having no such slots 139 into the side surfaces 121s of the cores 121, so as electrically to connect together the cores 121 and the projecting portions 136.
(3) The present invention should not be considered as being limited to the above described case in which the cores 121 and the projecting portions 136 are contacted together by the projecting portions 136 being bent against the side surfaces 121s of the cores 121. For example, instead of the projecting portions 136 projecting from the base portion 133 toward the center of the rotation shaft 188, the projecting portions 136 may be formed so as to be slightly inclined toward the cores 121. When positioning the conductive ring 130, the projecting portions 136 may be deformed in advance in the directions away from the cores 121 so that the projecting portions 136 contact the cores 121 due to their elastic restoring force after the conductive ring 130 is arranged them in position.
(4) The shapes of the conductive rings 130 and the conductive members 230 are not to be considered as being limited by the embodiments described above. Provided that it is possible electrically to connect together the side surfaces 121s of the cores 121 and the housing 180, it is possible to employ any of various shapes. Furthermore, the shapes of the conductive bars 161, 162 and the shapes of the groove portions 118 in which the conductive bars 161, 162 are received are also not to be considered as being limited by the embodiments described above. While, in the embodiments described above, examples were disclosed in which the cross sectional shapes of the conductive bars 161, 162 were rectangular, it would also be possible for them to be made with various other cross sectional shapes, such as, for example, circular shapes, semicircular shapes, elliptical shapes, polygonal shapes, or the like.
(5) The type of the motor is not to be considered as being limited by the embodiments described above. For example, it would also be acceptable to employ a switched reluctance motor (SR motor) having a rotor provided with a salient pole, instead of the magnets 152.
(6) While, in the embodiments described above, examples of axial gap type rotating electrical machines of the two rotor one stator type were explained, the present invention should not be considered as being limited to that configuration. It would also be possible to apply the present invention to a one rotor one stator type axial gap type rotating electrical machine.
(7) While, in the embodiments described above, examples were explained in which the cores 121 were made by laminating together the thin magnetic plates 121a which were made from an iron-based amorphous metallic material, the present invention should not be considered as being limited to that construction. For example, it would also be acceptable to arrange to make the cores 121 by laminating together magnetic steel sheets.
It would also be accept able to make the cores 121 from a soft magnetic material such as magnetic powder core material or the like. Even if the cores 121 are made from such a magnetic powder core material, it is still possible electrically to connect together the conductive rings 130 and the cores 121 in a reliable, simple, and easy manner by bending the bent prongs 137a of the conductive rings 130 and thereby electrically connecting them to the side surfaces of the cores 121, irrespective of the dimensional accuracy of the cores 121 in the radial direction.
(8) While, in the embodiments described above, it was arranged to press the bent prongs 137a into the side surfaces 121s of the cores 121, the present invention is not to be considered as being limited thereby. It would also be acceptable to arrange electrically to connect together the cores 121 and the bent prongs 137a by bending the bent prongs 137a, not so that they deform the cores 121, but rather so that they simply contact against the side surfaces of the cores 121.
(9) While, in the embodiments described above, examples were explained in which the projecting portions 136 and the side surfaces 121s of the cores 121 were electrically connected together, the present invention is not to be considered as being limited thereby. It will be sufficient if the conductive rings 130 are electrically connected to the projecting end portions 121e of the cores 121 in some manner.
(10) While, in the embodiments described above, examples were explained in which the cores 121 were shaped as trapezoidal prisms, the present invention is not to be considered as being limited thereby. For example, it would also be acceptable to arrange for the cores to be shaped as rectangular parallelepipeds. Moreover it would also be acceptable to arrange to make the cores 121 in a fan-shaped, by rolling up amorphous foil strips into a roll so as to form a wound iron core and by cutting the wound iron core so as to separate them in the circumferential direction.
(11) While, in the embodiments described above, examples were explained in which the conductive rings 130, 230 were provided in both axial directions of the stator 120, the present invention is not to be considered as being limited thereby. It would be sufficient to arrange to provide only one conductive ring 130, 230 in one axial direction.
(12) While, in the embodiments described above, examples were explained in which the cores 121 and the housing 180 are electrically connected together, the present invention is not to be considered as being limited thereby. It will be sufficient if at least one of the plurality of cores 121 is electrically connected to the housing 180. By doing this, it is possible to suppress the occurrence of stray current corrosion to a certain degree, as compared to a case in which none of the plurality of cores 121 are electrically connected to the housing 180.
(13) And while, in the first embodiment, an example was explained in which a pair of the groove portions 118 was provided to each of the pair of flange portions 112 of the bobbin 110 of each of the cores 121, and a conductive bar 161, 162 was housed in each of these groove portions 118, the present invention is not to be considered as being limited thereby. It would also be acceptable to arrange for the conductive bars 161, 162 to be provided to only one of the pair of flange portions 112. Moreover, it would also be possible to omit one of the pair of groove portions 118 in the flange portion 112, and only to provide one conductive bar in that one flange portion 112. Yet further, it would also be possible to provide a groove portion 118 in the bobbin 110 of at least one of the plurality of cores 121, and to house a conductive bar in that groove portion 118. By doing this, it is possible to obtain a certain beneficial shielding effect, as compared to a case in which no conductive bars are provided to the bobbin 110 of any of the plurality of cores 121.
(14) The order of the steps for manufacture, and the structures of the dies and the molds and so on, are not to be considered as being limited by the embodiments described above.
(15) While, in the third embodiment, an example was explained in which the cores 121 were held by the holding member 397 and then molded, the present invention is not to be considered as being limited by this arrangement. For example, instead of the holding member 397, it would also be possible to provide bolts that pass through the center housing 182 and the cores 121, and to hold the cores 121 with these bolts. Moreover, it would also be acceptable to arrange to hold the flange portions 112 of the bobbins 110, so as to cover the entire outer surfaces of the projecting end portions 121e of the cores 121 with the molded body 140.
(16) In the third embodiment, it would also be acceptable to arrange to omit the conductive rings 130 and/or the conductive bars 161, 162. It would be possible to provide a rotating electrical machine in which the strength with which the cores are held is increased, even if the conductive rings and/or the conductive bars are omitted.
(17) The number of the magnets 152 and the number of the cores 121 may be set as appropriate.
The present invention is not to be considered as being limited to the embodiments described above; provided that the essential characteristics of the present invention are preserved, other forms that are considered to come within the scope of the technical concept of the present invention are also included within the range of the present invention.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2013/081503 | 11/22/2013 | WO | 00 |