The present invention relates to a rotor, a rotating electric machine including the rotor, and a method of manufacturing the rotor.
In a rotating electric machine, AC power is supplied to stator windings, to generate a rotating magnetic field. The rotor is rotated by this rotating magnetic field. Also, the mechanical energy applied to the rotor can be converted into electric energy, and AC power can be output from coils. In view of this, a permanent-magnet rotating electric machine to be used for driving an electrically-driven vehicle such as a hybrid vehicle (or an electric vehicle (EV) is expected to have a higher rotating speed. Particularly, there is a demand for a permanent-magnet rotating electric machine that is capable of high power output even in a high-speed rotation range. Therefore, a rotating electric machine with buried permanent magnets having auxiliary salient poles is often used as a conventional permanent-magnet rotating electric machine. Such a rotating electric machine with buried permanent magnets is capable of field weakening at a time of high-speed rotation and can use reluctance torque. For example, PTL 1 discloses the structure of a permanent-magnet rotating electric machine that is capable of both high power output and mechanical high-speed rotation (see PTL 1, for example).
In the rotor of such a permanent-magnet rotating electric machine that can cope with high-speed rotation, magnet insertion holes each having a substantially rectangular cross-section are provided for respective magnetic poles. Long permanent magnets having a rectangular cross-section are inserted into the magnet insertion holes. Permanent magnets are inserted into the magnet insertion holes. When the rotating electric machine is driven, and the rotor is rotated, a high stress is applied, as a result of centrifugal force, particularly to the corner portion of each magnet insertion hole with which a corner portion of the corresponding permanent magnet is in contact. In a case where the stress is high, the magnets might be broken, or the rotor might be broken. In a rotating electric machine, AC power is supplied to coils, to generate a rotating magnetic field. The rotor is rotated by this rotating magnetic field. Also, in a rotating electric machine, the mechanical energy applied to the rotor is converted into electric energy, and AC power is output from the coils. That is, a rotating electric machine functions as an electric motor or a generator.
PTL 1: JP 2006-187189 A
In the rotor of the permanent-magnet rotating electric machine disclosed in PTL 1, a liquid filling material such as varnish enters between rotor cores, and therefore, a removal operation or the like is required in a post-process.
To solve the above problem, a structure disclosed in the claims is adopted, for example.
The present application discloses more than one means to solve the above problem. An example of the means is a rotor of a rotating electric machine. The rotor includes a permanent magnet and a rotor core having a magnet insertion hole into which the permanent magnet is inserted, the void between the permanent magnet and the magnet insertion hole being filled with a thermosetting powdered resin.
According to the present invention, it is possible to provide a rotor with high productivity, a rotating electric machine including the rotor, and a method of manufacturing the rotor.
The objects, structures, and effects other than the above will become apparent from the embodiments described below.
The following is a description of an embodiment of the present invention, with reference to the drawings.
A rotating electric machine according to this embodiment is a rotating electric machine suitable for use in automobile driving. Here, a so-called electric vehicle that uses a rotating electric machine may be a hybrid electric vehicle (HEV) that includes both an engine and a rotating electric machine, or a truly electric vehicle (EV) that runs only with a rotating electric machine and does not use an engine. The rotating electric machine described below can be used for both types, and therefore, the rotating electric machine described below is used in a hybrid automobile as a typical example.
Also, in the description below, the “axial direction” means the direction along the rotating shaft of the rotating electric machine. The circumferential direction is the direction along the direction of rotation of the rotating electric machine. The “radial direction” is the direction of the moving radius (radial direction), with the center being the rotating shaft of the rotating electric machine. The “inner circumferential side” is the inner side in the radial direction (the inner radial side), and the “outer circumferential side” is the opposite side or the outer side in the radial direction. (the outer radial side).
The stator 20 is secured to the inner circumferential side of the housing 50. The rotor 11 is rotatably supported by the inner circumferential side of the stator 20. The housing 50 is shaped into a cylindrical form by cutting of a ferrous metal such as carbon steel, casting of cast steel or aluminum alloy, stamping. The housing 50 forms the outer coating of the rotating electric machine. The housing 50 is called a casing or a frame.
The housing 50 is shaped into a cylindrical form by drawing of a steel sheet (such as a high-strength steel sheet) of about 2 to 5 mm in thickness. Flanges to be attached to a liquid-cooled jacket 130 are provided on the housing 50. The flanges protrude from the rim of an end face of the cylindrical housing 50 toward the outside in the radial direction. The flanges are formed by cutting of portions other than the flanges at the end portions formed at the time of drawing, and are integrally formed with the housing 50. Alternatively, the housing 112 may not be provided, and the stator 20 may be secured directly to the case.
The liquid-cooled jacket 130 is secured to the outer circumferential side of the housing 50. The inner circumferential wall of the liquid-cooled jacket 130 and the outer circumferential wall of the housing 50 constitute a refrigerant path 153 for a liquid refrigerant RF such as oil, and this refrigerant path 154 is designed not to cause any liquid leakage. The liquid-cooled jacket 130 houses bearings 144 and 145, and is also called a bearing bracket.
In the case of direct liquid cooling, the liquid as the refrigerant RF stored in a refrigerant (oil) storage space 150 passes through the refrigerant path 153, flows toward the stator 20 from refrigerant paths 154 and 155, and then cools the stator 20.
The stator 20 includes the stator core 132 and the stator coils 60. The stator core 132 is formed with stacked thin silicon steel sheets. The stator coils 60 are wound around a large number of slots 420 formed at the inner circumferential portion of the stator core 132. The heat generated from the stator coils 60 is transmitted to the liquid-cooled jacket 130 via the stator core 132, and is released by the refrigerant RF flowing in the liquid-cooled jacket 130.
The rotor 11 includes a rotor core 12 and a shaft 13. The rotor core 12 is formed with stacked thin silicon steel sheets. The shaft 13 is secured at the center of the rotor core 12. The shaft 13 is rotatably supported by the bearings 144 and 145 attached to the liquid-cooled jacket 130, and rotates in a predetermined position in the stator 20, the shaft 13 in the position facing the stator 20. A permanent magnet 18 and an end ring 19 are also provided in the rotor 11.
The rotating electric machine 10 is provided inside the liquid-cooled jacket 130 as shown in
This rotating electric machine 10 is a permanent-magnet-containing three-phase synchronous motor. As a three-phase alternating current is supplied to the stator coils 60 wound around the stator core 132, the rotating electric machine 10 functions as an electric motor that rotates the rotor 11. When being driven by an engine, the rotating electric machine 10 also functions as a generator, and generates three-phase AC power. That is, the rotating electric machine 10 has both the functions of an electric motor that generates rotating torque in accordance with electric energy, and the functions of a generator that generates power in accordance with mechanical energy. The functions can be selectively used in accordance with a running condition of the automobile.
The stator 20 includes the cylindrical stator core 132 and the stator coils 60 mounted on the stator core 132.
Referring now to
The number of the slots 420 is 72 in this embodiment, for example, and the above described stator coils 60 are accommodated by the slots 420. An opening is formed on the inner circumferential side of each slot 420, and the width of the opening in the circumferential direction is substantially the same or slightly smaller than the coil mounting portion of each slot 420 on which the stator coils 60 are mounted.
Teeth 430 are formed between the slots 420, and each of the teeth 430 is integrally formed with a ring-like core back 440. That is, the stator core 132 is an integrated core formed by integrally molding the teeth 430 and the core back 440.
The teeth 430 guide a rotating magnetic field generated by the stator coils 60 to the rotor 11, and function to cause the rotor 11 to generate rotating torque.
The stator core 132 is formed by molding electromagnetic steel sheets 133 of about 0.05 to 1.0 mm in thickness (see
Referring now to
Stator coils 138 are connected by a star connection structure shown in
The stator coils 60 are wound by a distributed winding method, and are connected by a star connection structure. Distributed winding is a winding method by which a phase winding is wound around the stator core 132 so that the phase winding is housed in two slots 420 between which more than one slot 420 exists. In this embodiment, distributed winding is adopted as the winding method. Therefore, the magnetic flux distribution to be formed is closer to sinusoidal waves than that with concentrated winding, and reluctance torque is easily generated. Accordingly, in this rotating electric machine 10, the controllability of control using field-weakening control and reluctance torque becomes higher. Thus, the rotating electric machine 10 can be used in a wide rotating speed range from a low rotating speed to a high rotating speed, and excellent motor characteristics suitable for electric vehicles can be achieved.
The stator coils 60 form star-connected phase coils of three phases, and may have a circular or rectangular cross-section. However, the cross-section in each slot 420 should be used as effectively as possible, and the spaces in the slots should be minimized, to achieve higher efficiency. Therefore, a rectangular cross-section is preferable in achieving higher efficiency. It should be noted that the rectangular cross-section of each stator coil 60 may be short in the circumferential direction and be long in the radial direction of the stator core 132. Alternatively, the rectangular cross-section may be long in the circumferential direction and be short in the radial direction of the stator core 132.
In this embodiment, rectangular wires are used as the stator coils 60 so that a rectangular cross-section of the stator coil 60 in each slot 420 is long in the circumferential direction of the stator core 132 and is short in the radial direction of the stator core 132. The outer circumferences of the rectangular wires are coated with an insulating coating.
An oxygen-free copper or an oxygen-containing copper is used as the stator coils 138. In the case of an oxygen-containing copper, the oxygen content is about 10 to 1000 ppm.
As shown in
Specifically, when viewed from the radial direction, the vertex 28C of the non-welding-side coil end 61 and diagonal conductor portions 28F of the non-welding-side coil end 61 do not necessarily form a triangular shape as in
The segment coil 28 is inserted into stator slots 420 from the axial direction. At a conductor end portion 28E, the segment coil 28 is then connected (by welding or the like) to another segment coil 28 inserted at a distance equivalent to a predetermined number of slots 420 as shown in
In this stage, straight conductor portions 28S that are the portions inserted into slots 420, and diagonal conductor portions 28D that are portions diagonally extending to the conductor end portions 28E of the segment coils 28 to which the segment coil 28 is connected are formed (the diagonal conductor portions 28D and the end portions 28E are formed by bending) in the segment coil 28.
Two, four, six, . . . (a multiple of 2) of segment coils 28 are inserted into a slot 420.
As shown in
AC terminals 41(U), 42(V), and 43(W) that are input/output coil conductors of the respective stator coils 60 of the U-, V-, and W phases, and neutral-point connecting conductors 40 are drawn to one coil end 140 of the stator coils 60.
It should be noted that, to improve the working efficiency in assembling the rotating electric machine 10, the AC terminals 41(U), 42(V), and 43(W) for receiving three-phase AC power are arranged to protrude from the coil end 140 to the outside in the axial direction of the stator core 132. The stator 20 is then connected to a power inverter (not shown) via the AC terminals 41(U), 42(V), and 43(W) so that AC power is supplied.
As shown in
The stator coils 60 are designed so that the outer circumferences of the conductors are coated with an insulating coating, and thus, electric insulation is maintained. However, insulating paper 300 (see
The insulating paper 300 is provided in the slots 420 and at the coil ends 140. The insulating paper 300 (so-called slot liners 310) provided in the slots 420 are provided between the segment coils 28 inserted in the slots 420 and between the segment coils 28 and the inner faces of the slots 420, to increase the withstand voltage between the segment coils and between the segment coils 28 and the inner faces of the slots 420.
The insulating paper 300 provided at the coil ends 140 are provided in a ring-like form between the segment coils, to insulate the coil ends 140 from each other and insulate the conductors from one another. The insulating paper 300 also serves as a holding member that prevents dripping of a resin member (such as polyester or liquid epoxy varnish) dropped on the entire or part of the stator coils.
As described above, in the rotating electric machine 10 according to this embodiment, the insulating paper 300 is provided in the slots 420 and at the coil ends 140. Thus, the necessary withstand voltage can be maintained, even if the insulating coating is damaged or deteriorates. It should be noted that the insulating paper 300 is an insulating sheet made of heat-resistant polyamide paper, and is about 0.1 to 0.5 mm in thickness.
The width of each magnet insertion hole 810 in the circumferential direction is greater than the width of each permanent magnet 18 in the circumferential direction, and magnetic voids 156 are formed on both sides of each permanent magnet 18.
The permanent magnets 18 function to form field poles of the rotor 11. In this embodiment, one permanent magnet forms one magnetic pole. However, each magnetic pole may be formed with more than one magnet. As the number of permanent magnets 18 is increased, the magnetic flux density of each magnetic pole generated by permanent magnets becomes higher, and magnetic torque can be increased.
The magnetization direction of the permanent magnets 18 is parallel to the radial direction, and the magnetization direction is reversed for each field pole. Specifically, where the stator-side face of a permanent magnet 18 for forming a certain magnetic pole is magnetized as the N-pole while the axis-side face thereof is magnetized as the S-pole, the stator-side face of a permanent magnet 18 forming an adjacent magnet pole is magnetized as the S-pole, and the axis-side face thereof is magnetized as the N-pole. These permanent magnets 18 are magnetized so that the magnetization direction is switched for each magnetic pole, and are arranged in the circumferential direction. In this embodiment, 12 permanent magnets 18 are arranged at regular intervals, and the rotor 11 forms 12 magnetic poles.
Here, neodymium- or samarium-based sintered magnets, ferrite magnets, neodymium-based bond magnets, or the like can be used as the permanent magnets 18.
In this embodiment, auxiliary magnetic poles 160 are formed between the permanent magnets 18 each forming a magnetic pole. The auxiliary magnetic poles 160 serve to lower the magnetic resistance of the q-axis magnetic flux generated by the stator coils 138. With the auxiliary magnetic poles 160, the magnetic resistance of the q-axis magnetic flux becomes much lower than the magnetic resistance of the d-axis magnetic flux. As a result, large reluctance torque is generated.
In a step 900, a smaller amount of powdered resin 800 than the void between each magnet insertion hole 810 and a permanent magnet 18 inserted.
An epoxy-based thermosetting resin is mainly used as the powdered resin 800. The powder particle size is 70 to 500 μm. The particle size of the powdered resin 800 is relatively large so that the powdered resin 800 is easily inserted into each magnet insertion hole 810. The glass-transition temperature of the powdered resin 800 depends on the usage environment, and is about 110 to 160 degrees.
In a step 910, the permanent magnets 18 are inserted into the respective magnet insertion holes 810.
In a step 920, after the permanent magnets 18 are inserted into the respective magnet insertion holes 810, the powdered resin 800 is thermally hardened while the rotor 11 is rotated. Being thermally hardened while being rotated, the respective magnet insertion holes 810 are evenly filled with the powdered resin 800. Thus, imbalance between the permanent magnets 18 can be minimized.
In a step 930, after the powdered resin 800 is hardened, balance adjustment is performed.
In a step 940, the permanent magnets 18 are magnetized.
As shown in
As shown in
In a case where powdered resin blocks 801 are used, scattering of the powdered resin can be prevented, and thus, working efficiency is increased. To increase the viscosity of the adhesive, the adhesive may be mixed with the powdered resin 800.
By any of the methods described above with reference to
By these methods, leakage of the adhesive and the like from the electromagnetic steel sheets 133 can be reduced. Also, where a liquid adhesive or the like is used, a gelation process is required. However, such a gelation process becomes unnecessary. As a result, productivity can be increased. Further, the powdered resin 800, 801, and 802 is applied onto the electromagnetic steel sheets 133 in the end. Thus, eddy current can be reduced, and motor efficiency can be increased.
A permanent-magnet rotating electric machine has been described so far. Since a feature of the present invention relates to a rotor, the stator is of a wave winding type. However, the stator may be of a multiple winding type or a concentrated winding type. An inward rotation type is next described, but an outward rotation type can also be used.
Referring now to
The rotating electric machines 10 activate the engine, and, in accordance with a running condition of the vehicle, switch between generation of a driving force and generation of power collected as electric energy from the energy when the vehicle slows down. Driving and power generating operations of the rotating electric machines 10 are controlled by a power inverter INV so that the torque and the number of revolutions are optimized in accordance with a driving situation of the vehicle. The power necessary for driving the rotating electric machines 10 is supplied from a battery BAT via the power inverter INV. When the rotating electric machines 10 are in power generating operations, the battery BAT is charged with electric energy via the power inverter INV.
Here, the rotating electric machine 10 as the power source on the front side is provided between the engine ENG and the transmission TR, and has the above described structure. As for the rotating electric machine 10 as the drive power source on the rear side, the same rotating electric machine as that on the front side may be used, or some other rotating electric machine having a conventional structure may be used. This is also applied to hybrid vehicle that is not of a four-wheel-drive type.
As described above, the present invention can provide a rotor for a rotating electric machine that has small eddy current and excellent motor efficiency.
It should be noted that the present invention is not limited to the above described embodiment, and includes various modifications. For example, the above described embodiment has been described in detail for ease of understanding of the present invention, and the present invention is not limited to a structure that includes all the components described above. Also, it is possible to add a component to the embodiment, delete one of the components of the embodiment, or replace one of the components of the embodiment with some other component.
Although rotating electric machines for electric vehicles and hybrid electric vehicles have been described as an example of application of the present invention, the present invention can also be applied to industrial motors for elevators and the like and motors for household appliances such as air-conditioner compressors, as well as auxiliary motors for automobiles, such as alternators, starter generators (including motor generators), electric compressors, and electric pumps.
Number | Date | Country | Kind |
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2015-172453 | Sep 2015 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2016/072094 | 7/28/2016 | WO | 00 |