JP5334555B2 - Electric motor and refrigerant compressor equipped with the same - Google Patents

Description

  The present invention relates to an electric motor used for various industrial machines such as an air conditioner and a refrigeration apparatus, and a refrigerant compressor equipped with the electric motor.

  In recent years, electric motors used in various industrial machines are required to be highly efficient and resource-saving (smaller and lighter) from the viewpoints of energy saving and environmental protection. As one of the realization methods, a permanent magnet type electric motor in which a magnet is inserted into a rotor has been proposed (for example, see Patent Document 1). The electric motor described in Patent Document 1 includes a stator configured by mounting a stator winding of a plurality of phases on a stator core, and a substantially plate-like permanent magnet in a form orthogonal to the radial direction inside the rotor core. A permanent magnet type electric motor comprising a rotor and a rotor arranged rotatably inside the stator core of the stator, and the outer surface of the rotor core at each end portion of the permanent magnet in the rotor core. A gap that extends to the vicinity is formed, and the thickness dimension of the portion (bridge portion) between the inner surface of the gap and the outer surface of the rotor core decreases from the end of the permanent magnet toward the adjacent permanent magnet. Is set to

JP 2000-217287 A (page 6, FIG. 1)

  The permanent magnet type electric motor described in Patent Document 1 forms a gap that extends to the outer surface of the rotor core at each end of the permanent magnet in the rotor core, and short-circuits the magnetic field between the ends of adjacent permanent magnets. Is preventing. As a result, the amount of magnetic flux interlinking the stator windings is increased, and the performance of the electric motor can be improved. However, the thickness dimension of the bridge portion set so as to decrease from the permanent magnet end side toward the adjacent permanent magnet side in order to withstand the centrifugal force of the permanent magnet or the rotor core itself due to the rotation, the permanent magnet portion On the side, it is thick, and the short-circuit prevention effect of the magnetic field has faded. If the bridge portion is thin, the mechanical strength cannot be maintained, and fatigue damage of the bridge portion is caused. Therefore, it is necessary to limit the number of rotation speed fluctuations and the maximum rotation speed, and the reliability is lowered.

  By the way, the rotor core is generally formed by punching and laminating a thin plate of a silicon steel plate, which is an electromagnetic steel plate, with a press die. It is generally known that the fatigue strength of this silicon steel sheet is affected by the state of the punched shear section and the residual stress due to the strain at the time of punching. In consideration of such manufacturing variation factors, it is necessary to set the thickness of the bridge portion, and as a result, the bridge portion becomes thick. If it does so, the short circuit prevention effect of the magnetic field in a bridge | bridging part will fade. The thickness limit of the bridge portion in the punching of the thin plate is generally about the plate thickness, and the thickness of the silicon steel plate is 0.2 to 0.5 mm as the limit of the thickness of the bridge portion. In that case, the bridge thickness is determined not by strength constraints but by processing constraints, and the best setting for preventing magnetic field short-circuiting may not be possible.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric motor with improved performance and reliability and a refrigerant compressor equipped with the electric motor.

An electric motor according to the present invention includes a stator having a plurality of stator windings mounted on a stator core, a rotor core having a plurality of magnet insertion holes for mounting permanent magnets, and the magnet insertion hole. A rotor having a permanent magnet inserted therein and rotatably disposed on an inner peripheral surface side of the stator core, and an outer periphery of the rotor core at each end of the magnet insertion hole. A gap portion extending near the surface and penetrating in the axial direction is formed, and a bridge portion having a predetermined thickness is provided between an end portion of the gap portion and an outer peripheral surface of the rotor core, and at least the rotor A plurality of recesses are formed on the outer peripheral surface of the rotor core facing the bridge portion.

An electric motor according to the present invention includes a stator having a plurality of stator windings mounted on a stator core, a rotor core having a plurality of magnet insertion holes for mounting permanent magnets, and the magnet insertion hole. A rotor having a permanent magnet inserted therein and rotatably disposed on an inner peripheral surface side of the stator core, and an outer periphery of the rotor core at each end of the magnet insertion hole. A gap portion extending near the surface and penetrating in the axial direction is formed, and a bridge portion having a predetermined thickness is provided between an end portion of the gap portion and an outer peripheral surface of the rotor core, and the bridge portion is It is characterized by being plastically deformed by applying pressure from the outer peripheral surface side of the rotor .

An electric motor according to the present invention includes a stator having a plurality of stator windings mounted on a stator core, a rotor core having a plurality of magnet insertion holes for mounting permanent magnets, and the magnet insertion hole. A rotor having a permanent magnet inserted therein and rotatably disposed on an inner peripheral surface side of the stator core, and an outer periphery of the rotor core at each end of the magnet insertion hole. A gap portion extending near the surface and penetrating in the axial direction is formed, and a bridge portion having a predetermined thickness is provided between an end portion of the gap portion and the outer peripheral surface of the rotor core, The outer peripheral surface of the rotor core is ground, and the surface roughness is made equal to or less than the crystal grain size of the electrical steel sheet constituting the rotor core.

  A refrigerant compressor according to the present invention includes the above-described electric motor.

  According to the electric motor of the present invention, it is possible to preliminarily apply a compressive residual stress to the bridge portion, to increase the effect of preventing short circuit of the magnetic field of the bridge portion, and to provide mechanical strength against the tensile stress of the bridge portion. Therefore, it is possible to obtain a highly efficient and high strength electric motor. Moreover, according to the refrigerant compressor which concerns on this invention, since the above-mentioned electric motor is mounted, it has all the effects which an electric motor has.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a longitudinal sectional view showing an example of a sectional configuration of a refrigerant compressor 100 on which an electric motor according to Embodiment 1 of the present invention is mounted. Based on FIG. 1, the structure and operation | movement of the refrigerant compressor 100 are demonstrated. This refrigerant compressor 100 is shown as an example of a scroll compressor. For example, a component of a refrigeration cycle (heat pump cycle) such as a refrigerator, a freezer, a vending machine, an air conditioner, a refrigeration apparatus, or a water heater. It will be. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

  The refrigerant compressor 100 sucks the refrigerant circulating in the refrigeration cycle, compresses it, and discharges it as a high-temperature and high-pressure state. The refrigerant compressor 100 can be classified into a compression unit 16 and a drive unit 17. The compression unit 16 and the drive unit 17 are accommodated in a sealed container (shell) 10. The sealed container 10 is a pressure container. As shown in FIG. 1, the compression unit 16 is disposed on the upper side of the sealed container 10, and the driving unit 17 is disposed on the lower side of the sealed container 10. The bottom of the hermetic container 10 is a sump 11 for storing the refrigerating machine oil 1. In addition, the closed container 10 is connected to a suction side pipe 12 for sucking refrigerant gas and a discharge side pipe 13 for discharging refrigerant gas.

  The compression unit 16 has a function of compressing the refrigerant gas sucked from the suction side pipe 12 and discharging it to the discharge space 15 in the sealed container 10. The refrigerant gas discharged into the discharge space 15 is discharged from the discharge side pipe 13 to the outside of the refrigerant compressor 100. The drive unit 17 serves to drive the orbiting scroll 24 constituting the compression unit 16 in order to compress the refrigerant gas by the compression unit 16. That is, when the drive unit 17 drives the orbiting scroll 24 via the crankshaft 21, the compression unit 16 compresses the refrigerant gas.

  The compression unit 16 is roughly configured by a turning scroll 24, a fixed scroll 28, and a frame 31. As shown in FIG. 1, the orbiting scroll 24 is arranged on the lower side, and the fixed scroll 28 is arranged on the upper side. The fixed scroll 28 is formed with a lap portion 29 which is a spiral projection standing on one surface. Further, the orbiting scroll 24 is also provided with a wrap portion 25 that is a spiral protrusion that is erected on one surface and has substantially the same shape as the wrap portion 29. The orbiting scroll 24 and the fixed scroll 28 are mounted in the sealed container 10 with the lap portion 25 and the lap portion 29 meshing with each other. And between the lap | wrap part 25 and the lap | wrap part 29, the compression chamber 18 from which a volume changes relatively is formed.

  The fixed scroll 28 is fixed to the frame 31 with a bolt or the like (not shown). A discharge port 30 for discharging the compressed and high-pressure refrigerant gas is formed at the center of the fixed scroll 28. The compressed and high pressure refrigerant gas is discharged into the discharge space 15 provided in the upper part of the fixed scroll 28. The orbiting scroll 24 performs a revolving orbiting movement without rotating about the fixed scroll 28. A hollow cylindrical orbiting scroll boss portion 26 is formed at a substantially central portion of a surface (hereinafter referred to as a thrust surface) opposite to the surface on which the orbiting scroll 24 forms the lap portion 25. An eccentric pin portion 22 provided at the upper end of a crankshaft 21 to be described later is fitted (engaged) with the orbiting scroll boss portion 26.

  The frame 31 is fixed to the inner peripheral surface of the sealed container 10, and a through hole is formed in the center portion for allowing the crankshaft 21 to pass therethrough. Further, the frame 31 is formed with an oil drain hole 32 penetrating from the thrust surface 27 side of the orbiting scroll 24 to the lower side in the axial direction so that the refrigerating machine oil 1 that lubricates the thrust surface 27 is returned to the sump 11. It has become. Although FIG. 1 shows an example in which only one oil drain hole 32 is formed, the present invention is not limited to this. For example, two or more oil drain holes 32 may be formed. Note that the outer peripheral surface of the frame 31 may be fixed to the inner peripheral surface of the sealed container 10 by shrink fitting, welding, or the like.

  The drive unit 17 includes a rotor 40 fixed to the crankshaft 21, a stator 20 housed in the hermetically sealed container 10 and fixedly held, and a crankshaft 21 that is a rotating shaft. The rotor 40 is fixed to the crankshaft 21 and is driven to rotate when the energization of the stator 20 starts to rotate the crankshaft 21. Further, the outer peripheral surface of the stator 20 is fixedly supported by the sealed container 10 by shrink fitting or the like. That is, the rotor 40 and the stator 20 constitute a motor (electric motor). The electric motor will be described in detail below.

  The stator 20 is configured by mounting a plurality of phases of stator windings (not shown) on a stator core (not shown). The crankshaft 21 rotates with the rotation of the rotor 40 to rotate the orbiting scroll 24. At the upper end portion of the crankshaft 21, an eccentric pin portion 22 that is rotatably fitted to the orbiting scroll boss portion 26 of the orbiting scroll 24 is formed. Further, an oil supply passage 23 communicating with the upper end surface is formed inside the crankshaft 21. The oil supply passage 23 becomes a passage for the refrigerating machine oil 1 stored in the sump 11. The refrigerating machine oil 1 accumulated in the oil sump 11 sucks up the refrigerating machine oil 1 as the crankshaft 21 rotates, flows through the oil supply passage 23, and is supplied to the compression unit 16.

  An Oldham ring 33 is disposed between the orbiting scroll 24 and the fixed scroll 28 to prevent the rotation of the orbiting scroll 24 during the eccentric orbiting movement. The Oldham ring 33 is disposed between the orbiting scroll 24 and the fixed scroll 28 and serves to prevent the orbiting scroll 24 from rotating and to enable a revolving orbiting movement. That is, the Oldham ring 33 functions as a rotation prevention mechanism for the orbiting scroll 24.

Here, the operation of the refrigerant compressor 100 will be briefly described.
The rotor 40 constituting the motor rotates in response to the rotational force from the rotating magnetic field generated by the stator 20. Accordingly, the crankshaft 21 fixed to the rotor 40 is driven to rotate. The orbiting scroll 24 is engaged with the eccentric pin portion 22 of the crankshaft 21, and the rotating rotation motion of the orbiting scroll 24 is converted into the revolution orbiting motion by the rotation preventing mechanism of the Oldham ring 33. As the crankshaft 21 rotates, the refrigerant gas in the hermetic container 10 flows into the compression chamber 18 formed by the lap portion 29 of the fixed scroll 28 and the lap portion 25 of the orbiting scroll 24, and the suction process starts.

  When the refrigerant gas is sucked into the compression chamber 18, the revolving orbiting motion of the eccentric orbiting scroll 24 shifts to a compression process for reducing the volume of the compression chamber 18. In other words, in the compression unit 16, when the orbiting scroll 24 revolves orbitally, the refrigerant gas is taken in from the outermost peripheral openings of the wrap portion 25 of the orbiting scroll 24 and the lap portion 29 of the fixed scroll 28 that serve as suction ports, and the orbiting scroll. It goes toward the center while being gradually compressed with the rotation of 24. The low-pressure refrigerant that has circulated through the refrigeration cycle flows into the sealed container 10 from the suction side pipe 12.

  Then, the refrigerant gas compressed in the compression chamber 18 moves to the discharge process. That is, the refrigerant gas passes through the discharge port 30 of the fixed scroll 28 and is discharged to the outside of the refrigerant compressor 100 after passing through the discharge space 15. The refrigerant discharged from the discharge side pipe 13 of the refrigerant compressor 100 is in a high-temperature and high-pressure state, and first flows into the condenser constituting the refrigeration cycle. It circulates and is sucked into the refrigerant compressor 100 again. Then, when the energization to the stator 20 is stopped, the refrigerant compressor 100 stops.

  FIG. 2 is an explanatory diagram for explaining the rotor 40 constituting the electric motor according to the first embodiment. The rotor 40 will be described in detail based on FIG. 2A is a plan view of the rotor 40, and FIG. 2B is a side view of the rotor 40. As described above, the rotor 40 is fixed to the crankshaft 21 and constitutes an electric motor (permanent magnet type electric motor) together with the stator 20 and the crankshaft 21. The rotor 40 is rotatably arranged on the inner peripheral surface side of the stator core constituting the stator 20.

  As shown in FIG. 2B, the rotor 40 includes a rotor core 41 in which a plurality of silicon steel plates (electromagnetic steel plates) 41a are stacked, and a magnet insertion hole 42 in which the rotor core 41 is penetrated in the axial direction. And a permanent magnet 43 attached to the. The rotor core 41 is formed with a rotating shaft insertion hole 49 and a magnet insertion hole 42 penetratingly formed. The rotation shaft insertion hole 49 is formed at the center of the rotor core 41, and the magnet insertion hole 42 is formed so as to surround the rotation shaft insertion hole 49. Further, the rotation shaft insertion hole 49 is formed in a substantially circular shape, and the magnet insertion hole 42 is formed in a substantially rectangular shape.

  In FIG. 2A, four magnet insertion holes 42 are formed every 90 °. The formation position of the magnet insertion hole 42 is determined according to the number of the magnet insertion holes 43. For example, when four magnet insertion holes 42 are formed as shown in FIG. 2 (a), a radial axis is determined every 90 ° by dividing 360 ° by 4, and the axis is opposed to the axis. The position may be determined as the magnet insertion hole 42. In addition, when three magnet insertion holes 42 are formed, a radial axis for each 120 ° obtained by dividing 360 ° by 3 may be determined, and the position on the axis may be determined as the magnet insertion hole 42.

  A plate-like permanent magnet 43 is attached to each of the magnet insertion holes 42. These permanent magnets 43 are mounted so that N poles and S poles are alternated. In addition, at each end of the magnet insertion hole 42, a gap 45 is formed that extends to the vicinity of the outer peripheral surface of the rotor core 41 and penetrates in the axial direction. That is, the gap 45 formed at each end of the magnet insertion hole 42 is formed by penetrating the rotor core 41 in the axial direction so as to go to the outer peripheral surface of the rotor core 41. Therefore, between the end of the gap 45 on the rotor core 41 side and the outer peripheral surface of the rotor core 41, a bridge portion 46 having a predetermined thickness (0.2 to 0.5 mm) is uniformly formed. Will be formed.

  Note that the thickness of the bridge portion 46 is determined in consideration of the performance of the electric motor. When the thickness of the bridge portion 46 is increased, the leakage of magnetic flux increases, and the performance of the electric motor is reduced. The upper limit of the thickness of the bridge portion 46 is as long as the performance of the electric motor is allowed. Basically, the lower limit of the thickness of the bridge portion 46 is determined by the reliability of the electric motor, and the minimum necessary value that does not impair the reliability of the electric motor is the lower limit value of the thickness of the bridge portion 46.

  The bridge portion 46 prevents a short circuit of a magnetic field generated from the permanent magnet 43 of the rotor 40 that houses the permanent magnet 43. Therefore, it is preferable that the bridge portion 46 is thin in order to improve the performance of the electric motor. On the other hand, since the centrifugal force of the permanent magnet 43 and the rotor core 41 itself generated by rotating acts on the bridge portion 46, the mechanical strength is reduced if the bridge portion 46 is too thin. In particular, in an electric motor that is subjected to speed change control, repeated stress acts on the bridge portion 46. Therefore, at least the outer peripheral surface of the rotor 40 facing the bridge portion 46 is shot blasted to form a plurality of dimple-shaped recesses 47.

  In the rotor 40 configured as described above, a plurality of concave portions 47 are formed on the outer peripheral surface of the rotor core 41 facing the bridge portion 46 and the thickness of the bridge portion 46 is uniformly reduced. The magnetic properties (permeability) of the silicon steel plate 41a in the whole can be deteriorated. That is, since it becomes difficult for the magnetic field to pass through the bridge portion 46, the effect of preventing the short circuit of the magnetic field of the bridge portion 46 can be improved. Further, by forming a plurality of concave portions 47 on the outer peripheral surface of the rotor core 41 facing the bridge portion 46, compression residual stress can be given to the bridge portion 46 in advance, and repeated occurrence caused by rotation during compression. Fatigue damage of the bridge portion 46 due to stress can be suppressed. In other words, by applying a compressive residual stress to the bridge portion 46 in advance, the mechanical strength against the tensile stress of the bridge portion 46 can be improved.

  From the above, it is possible to obtain an electric motor with improved performance and strength as compared with an electric motor in which the rotor 40 is not formed with the dimple-shaped recess 47 by shot blasting. The number, size, interval, etc. of the recesses 47 are not particularly limited. Moreover, although the case where the thickness of the bridge | bridging part 46 was 0.2-0.5 mm comparable as the thickness of the silicon steel plate 41a which comprises the rotor core 41 was demonstrated to the example, this is the silicon steel plate 41a. The thickness is determined from the limit in the punching process, and may be formed so as to become thinner as the technology advances.

  FIG. 3 is an explanatory diagram for explaining an embodiment of shot blasting. Based on FIG. 3, an example of shot blasting will be specifically described. FIG. 3A shows a state in which the rotor 40 during shot blasting is viewed from the side, and FIG. 3B shows a state in which the rotor 40 during shot blasting is viewed from above. Here, a case where a blast having a particle diameter of about 0.1 mm is ejected from the shot blast nozzle 51 of the shot blast apparatus 50 and collides with the side surface of the rotor 40 will be described as an example.

  First, the rotor 40 is prepared, and the shot blasting device 50 is provided with a masking 52 in a wider range than the position facing the bridge portion 46 so that the blast collides with the rotor 40 at least at a position facing the bridge portion 46. Set (FIG. 3B). Then, the rotor 40 is rotated about the axis and blast (arrow) is ejected from the shot blast nozzle 51. By doing so, a plurality of dimple-shaped concave portions 47 are formed at positions facing the bridge portion 46. In order to control the residual stress, the initial speed (v) of blast, the distance (l) between the shot blast nozzle and the outer peripheral surface of the rotor 40, the shot time (t), etc. may be adjusted. And compressive residual stress is given so that the yield point which material (material which comprises the rotor core 41) has may not be exceeded.

  For example, if compressive residual stress of about 150 MPa is applied to a material having a yield point of 300 MPa, the load resistance for −150 MPa increases as tensile stress. Since the fatigue limit of a material having a yield point of 300 MPa is generally about half of +150 MPa, a load resistance of 300 MPa is obtained from −150 MPa to +150 MPa. Therefore, by forming the concave portion 47, it becomes possible to have a double load resistance compared to the case where there is no residual stress. Accordingly, since the thickness of the bridge portion 46 can be reduced, the efficiency of the electric motor can be improved and the life can be extended.

Embodiment 2. FIG.
FIG. 4 is an explanatory diagram for explaining a rotor 40a constituting the electric motor according to Embodiment 2 of the present invention. The rotor 40a will be described in detail based on FIG. FIG. 4 shows a plan view of the rotor 40a. The basic configuration of the rotor 40a is the same as that of the rotor 40 described in the first embodiment. In the second embodiment, differences from the first embodiment will be mainly described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

  Similar to the rotor 40, the rotor 40a is fixed to the crankshaft 21 and constitutes an electric motor (permanent magnet type electric motor) together with the stator 20 and the crankshaft 21. Further, the rotor 40a is rotatably disposed on the inner peripheral surface side of the stator core that constitutes the stator 20. The rotor 40a is different from the rotor 40 described in the first embodiment in that at least the bridge portion 46 of the rotor 40a is plastically deformed. That is, the bridge portion 46 (hereinafter referred to as the bridge portion 46a) of the rotor core 41 constituting the rotor 40a is pressed and plastically deformed from the outer peripheral surface side.

  In the rotor 40a configured as described above, the bridge portion 46a of the rotor core 41 is plastically deformed and the thickness of the bridge portion 46a is uniformly reduced. Therefore, the magnetic characteristics of the silicon steel plate 41a in the entire bridge portion 46a ( (Magnetic permeability) can be deteriorated, and the bridge portion 46a can be plastically deformed to lengthen the magnetic path, thereby further enhancing the effect of preventing the short circuit of the magnetic field of the bridge portion 46a. That is, since it becomes difficult for the magnetic field to pass through the bridge portion 46a, the effect of preventing the short circuit of the magnetic field of the bridge portion 46 can be improved.

  Further, the bridge portion 46a of the rotor core 41 is plastically deformed, so that compressive residual stress can be applied to the bridge portion 46a in advance, and fatigue damage of the bridge portion 46a due to repeated stress generated by rotation at the time of compression. Can be suppressed. That is, the mechanical strength against the tensile stress of the bridge portion 46a can be improved by applying a compressive residual stress to the bridge portion 46a in advance.

  From the above, it is possible to obtain a motor with improved performance and strength as compared with a motor in which the bridge portion 46a of the rotor 40a is not plastically deformed. FIG. 4 shows an example in which the bridge portion 46a is pressurized from the outer peripheral surface toward the axial center, and a concave portion extending linearly in the axial direction is formed and plastically deformed. However, the present invention is limited to this. What is necessary is just to determine according to the magnitude | size of the rotor 40a, the material of the rotor core 41 which comprises the rotor 40a, etc. instead of a thing. Further, the shape, size, interval, and the like of the plastic deformation of the bridge portion 46a are not particularly limited. Furthermore, the shape of the rotor core 41 can be made as shown in advance, but it is desirable that the rotor core 41 be plastically deformed after formation in order to give a residual stress in advance.

Embodiment 3 FIG.
FIG. 5 is an explanatory diagram for explaining the rotor 40b constituting the electric motor according to Embodiment 3 of the present invention. The rotor 40b will be described in detail based on FIG. 5A is a plan view of the rotor 40b, and FIG. 5B is a side view of the rotor 40b. The basic configuration of the rotor 40b is the same as that of the rotor 40 described in the first embodiment. In the third embodiment, differences from the first and second embodiments will be mainly described, and the same parts as those in the first and second embodiments will be denoted by the same reference numerals and the description thereof will be omitted. It shall be.

  Similarly to the rotor 40, the rotor 40 b is also fixed to the crankshaft 21 and constitutes an electric motor (permanent magnet type electric motor) together with the stator 20 and the crankshaft 21. The rotor 40b is rotatably disposed on the inner peripheral surface side of the stator core that constitutes the stator 20. The rotor 40b includes the rotor 40 described in the first embodiment and the rotor 40a described in the second embodiment in that the outer peripheral surface of the rotor core 41 constituting the rotor 40b is ground. It is different.

  It is assumed that the grinding of the outer peripheral surface of the rotor core 41 is performed after the punching of the silicon steel plate 41a to be the rotor core 41. By doing so, the thickness dimension of the bridge portion 46 (hereinafter referred to as the bridge portion 46b) restricted by the punching process of the silicon steel plate 41a can be made the minimum necessary in terms of strength. Generally, the thickness dimension that is the restriction for punching the silicon steel plate 41a is up to the thickness (0.2 to 0.5 mm) of the silicon steel plate 41a. Therefore, by grinding after punching the silicon steel plate 41a, the thickness of the bridge portion 46b can be reduced to 0.2 mm or less.

  Further, the density of the punched shear surface can be improved by grinding. By making the surface roughness of the silicon steel plate 41a after grinding smaller than the surface roughness of the silicon steel plate 41a before grinding, small cracks generated in the punched shear surface can be removed, and the crystal grains Interface cracks are not seen (see FIG. 6). It is generally known that the state of the punched shear surface greatly affects the mechanical strength of the silicon steel plate 41a. This is caused by a small crack in the punched shear surface of the silicon steel plate 41a. Moreover, the crystal grain interface of the silicon steel plate 41a is weak in bonding force and easily cracked. Overall, these factors have a particularly negative impact on yield strength. Therefore, in the rotor 40b, the silicon steel plate 41a after punching is ground.

  In the rotor 40b configured as described above, since the outer peripheral surface of the rotor 40b is ground, the bridge portion 46b of the rotor core 41 can be set to the minimum necessary thickness in terms of strength. And the crack of a punching shear surface and the crack of a crystal grain interface can be removed. Therefore, the mechanical strength can be increased and the variation in strength can be suppressed, so that the thickness of the bridge portion 46b can be further reduced uniformly. Therefore, the magnetic properties (magnetic permeability) of the silicon steel plate 41a in the entire bridge portion 46b can be deteriorated, and the magnetic field short-circuit prevention effect of the bridge portion 46b can be enhanced. From the above, it is possible to obtain an electric motor with improved performance and strength as compared with an electric motor in which the outer peripheral surface of the rotor 40b is not ground.

  FIG. 6 is an explanatory diagram for explaining the effect produced by grinding the rotor core 41. Based on FIG. 6, the effect which arises by grinding the rotor core 41 is demonstrated concretely. 6 (a) shows a cross-sectional state in which the silicon steel plate 41a has been punched, FIG. 6 (b) shows an enlarged cross-section of the silicon steel plate 41a, and FIG. 6 (c) shows a cross-section of the silicon steel plate 41a that has been ground. Each of the states is enlarged.

  First, the silicon steel plate 41a which comprises the rotor core 41 of the rotor 40b is prepared. This silicon steel plate 41a is set in a press machine. At this time, an unnecessary portion of the silicon steel plate 41a is placed on the table. And as shown to Fig.6 (a), a metal mold punch is pressed with a press of several 10 to several 100 tons, and a product (part used as the rotor core 41) and an unnecessary part are separated. At that time, an excessive load and impact are applied to the product. The silicon steel plate 41a is composed of fine crystals as shown in FIG. Therefore, when the silicon steel plate 41a is punched out, the space between the crystal grains becomes a minute notch and is exposed to the outer surface of the silicon steel plate 41a.

  When such a notch is exposed, the fatigue source is reduced as described in, for example, Japanese Patent Application Laid-Open No. 2001-234303 (see paragraph [0009] of the specification, etc.). That is, the minute notch is the starting point, and the silicon steel plate 41a is easily destroyed, and the fatigue life is shortened. Therefore, in the rotor 40b, the fine notch is scraped off by grinding the silicon steel plate 41a constituting the rotor core 41 (FIG. 6C). As a result, the roughness of the rough surface is reduced, and the strength of the silicon steel plate 41a is improved. Note that if the machining allowance by grinding is greater than the grain size of the crystals constituting the silicon steel plate 41a (for example, about 100 μm), the defects can be reduced.

It is a longitudinal cross-sectional view which shows an example of the cross-sectional structure of the refrigerant compressor with which the electric motor which concerns on Embodiment 1 is mounted. FIG. 3 is an explanatory diagram for explaining a rotor constituting the electric motor according to the first embodiment. It is explanatory drawing for demonstrating one Example of shot blasting. FIG. 5 is an explanatory diagram for explaining a rotor that constitutes an electric motor according to a second embodiment. FIG. 10 is an explanatory diagram for explaining a rotor constituting an electric motor according to a third embodiment. It is explanatory drawing for demonstrating the effect produced by grinding a rotor core.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Refrigerating machine oil, 10 airtight container, 12 suction side piping, 13 discharge side piping, 15 discharge space, 16 compression part, 17 drive part, 18 compression chamber, 20 stator, 21 crankshaft, 22 eccentric pin part, 23 oil supply flow Road, 24 orbiting scroll, 25 lap part, 26 orbiting scroll boss part, 27 thrust surface, 28 fixed scroll, 29 lap part, 30 discharge port, 31 frame, 32 oil drain hole, 33 Oldham ring, 40 rotor, 40a rotation 40b rotor, 41 rotor core, 41a silicon steel plate, 42 magnet insertion hole, 43 permanent magnet, 45 gap, 46 bridge, 46a bridge, 46b bridge, 47 recess, 49 rotation shaft insertion hole, 50 Shot blasting device, 51 Shot blast nozzle, 52 Masking, 100 Refrigerant compressor.

Claims (9)

A stator having a multi-phase stator winding mounted on the stator core;
A rotor core having a plurality of magnet insertion holes for mounting permanent magnets, and a permanent magnet inserted into the magnet insertion hole, are rotatably arranged on the inner peripheral surface side of the stator core. A rotor, and
At each end of the magnet insertion hole, a gap that extends to the vicinity of the outer peripheral surface of the rotor core and penetrates in the axial direction is formed. Between the end of the gap and the outer peripheral surface of the rotor core Is provided with a bridge portion of a predetermined thickness,
A plurality of recesses are formed on the outer peripheral surface of the rotor core facing at least the bridge portion of the rotor . The recess is
The electric motor according to claim 1, wherein the electric motor is formed by shot blasting. A stator having a multi-phase stator winding mounted on the stator core;
A rotor core having a plurality of magnet insertion holes for mounting permanent magnets, and a permanent magnet inserted into the magnet insertion hole, are rotatably arranged on the inner peripheral surface side of the stator core. A rotor, and
At each end of the magnet insertion hole, a gap that extends to the vicinity of the outer peripheral surface of the rotor core and penetrates in the axial direction is formed. Between the end of the gap and the outer peripheral surface of the rotor core Is provided with a bridge portion of a predetermined thickness,
The motor is characterized in that the bridge portion is pressed from the outer peripheral surface side of the rotor to be plastically deformed . The electric motor according to any one of claims 1 to 3 , wherein a thickness of the bridge portion is substantially equal to a thickness of an electromagnetic steel plate constituting the rotor core. A stator having a multi-phase stator winding mounted on the stator core;
A rotor core having a plurality of magnet insertion holes for mounting permanent magnets, and a permanent magnet inserted into the magnet insertion hole, are rotatably arranged on the inner peripheral surface side of the stator core. A rotor, and
At each end of the magnet insertion hole, a gap that extends to the vicinity of the outer peripheral surface of the rotor core and penetrates in the axial direction is formed. Between the end of the gap and the outer peripheral surface of the rotor core Is provided with a bridge portion of a predetermined thickness,
An electric motor, wherein the outer peripheral surface of the rotor core of the rotor is ground so that the surface roughness is equal to or less than the crystal grain size of the electromagnetic steel sheet constituting the rotor core. 6. The electric motor according to claim 5 , wherein a machining allowance by the grinding process is set to be equal to or larger than a crystal grain size of an electromagnetic steel sheet constituting the rotor core. Grinding of the outer peripheral surface of the rotor,
The electric motor according to claim 5 or 6 , wherein the electric motor is performed after a punching step of the electromagnetic steel sheet constituting the rotor core. The electric motor according to any one of claims 5 to 7 , wherein a thickness of the bridge portion is made thinner than a thickness of an electromagnetic steel plate constituting the rotor core. A refrigerant compressor comprising the electric motor according to any one of claims 1 to 8 .

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