Stator, motor, compressor, and air conditioner

Abstract

The stator (2) is disposed on the outside of the rotor of a motor disposed in a compressor used with a refrigerant containing a substance that undergoes a disproportionation reaction. The stator (2) has a yoke portion (21a) and N teeth (22a). Each of the N teeth (22a) has a tooth tip surface (223a) facing the rotor (3). When the angle θ1 [degrees] is formed by two lines passing through both ends of the tooth tip surface (223a) and the center of rotation of the rotor (3) in a plane perpendicular to the axial direction of the rotor (3), the angle satisfies 0.75≦(θ1×N) / 360≦0.97.

Description

[Technical Field]

[0001] The present invention relates to a stator for a motor. [Background technology]

[0002] Generally, a refrigerant containing 1,1,2-trifluoroethylene is used as a refrigerant for a compressor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 136977 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, depending on the structure of the motor in the compressor, the refrigerant may expand and cause the cylinder in the compressor to break down, which may result in the compressor breaking down.

[0005] An object of the present invention is to solve the above-mentioned problems and to make compressor failure less likely to occur. [Means for solving the problem]

[0006] A stator according to one aspect of the present invention includes: A stator disposed on the outside of a rotor of a motor disposed in a compressor used with a refrigerant containing a substance that has a property of undergoing a disproportionation reaction, a stator core having a plurality of sheets stacked in the axial direction of the rotor; The stator core is It consists of multiple core sections that are divided into annular sections and arranged in the circumferential direction. A yoke portion and N teeth portions are provided. each of the N tooth portions has a tooth tip surface facing the rotor, the curvature of the tooth tip surface is constant in a plane perpendicular to the axial direction, When the angle formed by two lines passing through both ends of the tooth tip surfaces and the center of rotation of the rotor in a plane perpendicular to the axial direction is θ1 [degrees], Each of the plurality of sheets has a thickness of 0.75≦(θ1×N) / 360≦0.97 Meet the following. A motor according to another aspect of the present invention comprises: the stator; the rotor disposed inside the stator; Equipped with. A compressor according to another aspect of the present invention includes: A sealed container and a compression device disposed within the sealed container; the motor that drives the compression device; Equipped with. An air conditioner according to another aspect of the present invention comprises: the compressor; Heat exchanger and Equipped with. [Effects of the Invention]

[0007] According to the present invention, it is possible to make compressor failure less likely to occur. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically showing the internal structure of a motor including a stator according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing the configuration of a drive device. [Figure 3] FIG. 2 is a perspective view showing a schematic structure of a core segment; [Figure 4] FIG. 2 is a plan view schematically showing the structure of a stator core. [Figure 5] FIG. 3 is a cross-sectional view schematically showing the structure of a split core portion. [Figure 6] FIG. 2 is a plan view schematically showing the structure of the iron core portion. [Figure 7]FIG. 2 is a perspective view schematically showing the structure of an iron core portion. [Figure 8] FIG. 2 is a cross-sectional view schematically showing the structure of a rotor. [Figure 9] 3A and 3B are diagrams illustrating the structure of a teeth portion. [Figure 10] FIG. 10 is a cross-sectional view schematically showing another example of a motor. [Figure 11] FIG. 10 is a cross-sectional view schematically showing yet another example of a motor. [Figure 12] FIG. 2 is a plan view schematically illustrating an example of a metal member. [Figure 13] FIG. 10 is a diagram illustrating another example of a rotor. [Figure 14] 4 is a graph showing the relationship between the rotation angle of the rotor and the internal pressure in the cylinder. [Figure 15] 10 is a graph showing the relationship between the opening angle rate [%] and the torque ripple rate [%] when the motor is driven at a torque equal to or less than the rated torque. [Figure 16] FIG. 10 is a diagram showing the magnetic flux density in the stator core when the motor is driven at a torque equal to or less than the rated torque. [Figure 17] FIG. 10 is a diagram showing the magnetic flux density in the stator core when the motor is driven with a torque greater than the rated torque. [Figure 18] 10 is a graph showing the relationship between the opening angle rate [%] and the torque ripple rate [%] when the motor is driven with a torque greater than the rated torque. [Figure 19] FIG. 5 is a cross-sectional view schematically showing the structure of a compressor according to a second embodiment of the present invention. [Figure 20] FIG. 10 is a diagram showing a schematic configuration of a refrigeration and air conditioning system according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment 1 In the xyz Cartesian coordinate system shown in each figure, the z-axis direction (z-axis) indicates a direction parallel to the axis A1 of the motor 1, the x-axis direction (x-axis) indicates a direction perpendicular to the z-axis direction (z-axis), and the y-axis direction (y-axis) indicates a direction perpendicular to both the z-axis direction and the x-axis direction. The axis A1 is the center of rotation of the rotor 3. The axis A1 also indicates the center of the stator 2. The direction parallel to the axis A1 is also called the "axial direction of the motor 1," the "axial direction of the rotor 3," or simply the "axial direction." The radial direction is the radial direction of the rotor 3 or the stator 2 and is a direction perpendicular to the axis A1. The xy plane is a plane perpendicular to the axial direction. The arrow D1 indicates the circumferential direction centered on the axis A1. The circumferential direction of the rotor 3 or the stator 2 is also simply called the "circumferential direction."

[0010] FIG. 1 is a cross-sectional view that schematically shows the internal structure of a motor 1 that includes a stator 2 according to a first embodiment of the present invention. The motor 1 includes a stator 2 and a rotor 3. The motor 1 is, for example, an embedded permanent magnet motor.

[0011] The motor 1 is, for example, a motor disposed in a compressor used with a refrigerant containing a substance that has the property of causing a disproportionation reaction.

[0012] For example, the refrigerant may contain 1 wt% or more of a substance capable of causing a disproportionation reaction. The refrigerant may also be composed solely of a substance capable of causing a disproportionation reaction. That is, the proportion of the substance capable of causing a disproportionation reaction in the refrigerant may be between 1 wt% and 100 wt%.

[0013] The substance capable of undergoing a disproportionation reaction is, for example, 1,1,2-trifluoroethylene or 1,2-difluoroethylene.

[0014] For example, the refrigerant may contain 1 wt% or more of 1,1,2-trifluoroethylene. The refrigerant may be composed solely of 1,1,2-trifluoroethylene. That is, the refrigerant may contain 1 wt% to 100 wt% of 1,1,2-trifluoroethylene.

[0015] For example, the refrigerant may contain 1 wt% or more of 1,2-difluoroethylene. The refrigerant may be composed solely of 1,2-difluoroethylene. That is, the refrigerant may contain 1 wt% to 100 wt% of 1,2-difluoroethylene.

[0016] The refrigerant may be a mixture of 1,1,2-trifluoroethylene and difluoromethane (also referred to as R32). For example, a mixture containing 40 wt% 1,1,2-trifluoroethylene and 60 wt% R32 can be used as a refrigerant. The R32 in this mixture may be replaced with another substance. For example, a mixture of 1,1,2-trifluoroethylene and another ethylenically fluorinated hydrocarbon may be used as a refrigerant. Examples of other ethylenically fluorinated hydrocarbons that can be used include fluoroethylene (also referred to as HFO-1141), 1,1-difluoroethylene (also referred to as HFO-1132a), trans-1,2-difluoroethylene (also referred to as "HFO-1132(E)"), and cis-1,2-difluoroethylene (also referred to as "HFO-1132(Z)").

[0017] R32 may be replaced by any of 2,3,3,3-tetrafluoropropene (also referred to as R1234yf), trans-1,3,3,3-tetrafluoropropene (also referred to as "R1234ze(E)"), cis-1,3,3,3-tetrafluoropropene (also referred to as "R1234ze(Z)"), 1,1,1,2-tetrafluoroethane (also referred to as R134a), and 1,1,1,2,2-pentafluoroethane (also referred to as R125). R32 may also be replaced by a mixture of two or more of R32, R1234yf, R1234ze(E), R1234ze(Z), R134a, and R125.

[0018] The stator 2 has a stator core 2a formed in an annular shape and a coil 27 wound around the stator core 2a. The stator 2 is formed in an annular shape in the circumferential direction centered on the axis A1 (i.e., the center of rotation of the rotor 3).

[0019] The stator 2 is disposed outside the rotor 3. The rotor 3 is rotatably mounted inside the stator 2. An air gap of 0.3 mm to 1 mm is provided between the inner surface of the stator 2 and the outer surface of the rotor 3. When a current is supplied from the inverter to the coil 27 of the stator 2, the rotor 3 rotates. The current supplied to the coil 27 has a frequency synchronized with the command rotation speed.

[0020] The stator 2 has a plurality of split core portions 25a. In the example shown in Fig. 1, the plurality of split core portions 25a are arranged in an annular shape in the circumferential direction around the axis A1, thereby forming the stator 2.

[0021] Next, the driving device 101 will be described. FIG. 2 is a block diagram showing the configuration of the driving device 101. The motor 1 may have a driving device 101 shown in Fig. 2. The driving device 101 has a converter 102 that rectifies the output of a power supply, an inverter 103 that supplies power to the stator 2 (specifically, the coil 27) of the motor 1, and a control device 50.

[0022] In the example shown in FIG. 2, the coil 27 is a three-phase coil having a U-phase, a V-phase, and a W-phase.

[0023] The converter 102 is supplied with power from a power supply, which is an AC power supply. The converter 102 applies a voltage to the inverter 103. The voltage applied from the converter 102 to the inverter 103 is also referred to as a “converter voltage.” The bus voltage of the converter 102 is supplied to the control device 50.

[0024] The inverter 103 operates by a pulse width modulation control method (also called a PWM control method).

[0025] The inverter voltage that drives the motor 1, i.e., the voltage applied to the coil 27 of the motor 1, is generated by a PWM control method. As described above, the coil 27 of the motor 1 is, for example, a three-phase coil. In this case, the inverter 103 has at least one inverter switch corresponding to each phase, and each inverter switch has a set of switching elements (two switching elements in this embodiment).

[0026] In the PWM control method, the inverter voltage waveform is generated by controlling the on / off time ratio of the inverter switch corresponding to each phase. This makes it possible to obtain a desired output waveform from the inverter 103. Specifically, when the inverter switch in the inverter 103 is on, voltage is supplied from the inverter 103 to the coil 27, and the inverter voltage increases. When the inverter switch is off, the voltage supply from the inverter 103 to the coil 27 is cut off, and the inverter voltage drops. The difference between the inverter voltage and the induced voltage is supplied to the coil 27, generating a motor current and torque for the motor 1. By controlling the on / off time ratio of the inverter switch so that it matches the target motor current value, it is possible to obtain a desired output waveform from the inverter 103.

[0027] The on / off timing of each inverter switch is determined based on a carrier wave. The carrier wave is composed of a triangular wave with a constant amplitude. The pulse width modulation period in the PWM control method is determined by the carrier frequency, which is the frequency of the carrier wave. In this embodiment, a predetermined carrier wave pattern or a predetermined carrier frequency is stored in the control device 50. The control device 50 controls the carrier frequency and controls the on / off of each inverter switch. In this way, the control device 50 controls the output from the inverter 103 supplied to the coil 27.

[0028] The carrier frequency of the carrier wave is also referred to as the “carrier frequency of the inverter 103.” That is, the carrier frequency of the inverter 103 is the control frequency of the voltage applied to the coil 27, and the control device 50 controls the carrier frequency of the inverter 103.

[0029] In this embodiment, inverter 103 has three inverter switches (i.e., six switching elements), and the control of one of the three inverter switches, i.e., the inverter switch corresponding to the U phase, V phase, or W phase, will be described. However, the control of that one inverter switch can also be applied to the control of the other two inverter switches.

[0030] The control device 50 compares the voltage value of the carrier wave with an inverter output voltage command value. The inverter output voltage command value is calculated, for example, by the control device 50 based on a target motor current value. The inverter output voltage command value is set, for example, based on an operation instruction signal input to the control device 50 from a remote control of a refrigeration and air conditioning device such as an air conditioner.

[0031] When the voltage value of the carrier wave is smaller than the inverter output voltage command value, the control device 50 turns on the PWM control signal so that the inverter switch is turned on. When the voltage value of the carrier wave is equal to or greater than the inverter output voltage command value, the control device 50 turns off the PWM control signal so that the inverter switch is turned off. This causes the inverter voltage to approach the target value.

[0032] As described above, the control device 50 generates a PWM control signal based on the difference between the inverter output voltage command value and the voltage value of the carrier wave.

[0033] The control device 50 outputs a control signal, such as an inverter drive signal based on the PWM control signal, to the inverter 103 to control the on / off of the inverter switch. The inverter drive signal may be the same signal as the PWM control signal or may be a signal different from the PWM control signal.

[0034] When the inverter switch is on, an inverter voltage is output from the inverter 103. The inverter voltage is supplied to the coil 27, and a motor current (specifically, a U-phase current, a V-phase current, and a W-phase current) is generated in the motor 1. This converts the inverter voltage into a rotational force of the motor 1 (specifically, the rotor 3). The motor current is measured by a measuring instrument such as a current sensor, and the measurement result (for example, a signal indicating a current value) is sent to the control device 50.

[0035] The control device 50 is configured with, for example, a processor and a memory. For example, the control device 50 is a microcomputer. The control device 50 may be configured with a processing circuit as dedicated hardware, such as a single circuit or a composite circuit.

[0036] The structure of the core segments 25a will be described below. FIG. 3 is a perspective view that schematically shows the structure of the core segment 25a.

[0037] In this embodiment, the stator 2 is made up of a plurality of split core portions 25a. Each split core portion 25a has a split core portion 21, a first insulator 24a, a second insulator 24b, and a coil 27. However, in the example shown in Fig. 3, the coil 27 is not shown.

[0038] The first insulator 24a is combined with the stator core 2a (specifically, the core portion 21). In this embodiment, the first insulator 24a is provided at both ends of the stator core 2a in the axial direction. However, the first insulator 24a may also be provided at one end of the stator core 2a in the axial direction. In this embodiment, the first insulator 24a is made of insulating resin.

[0039] The second insulator 24b is, for example, a thin PET (polyethylene terephthalate) film. The thickness of the PET film is, for example, 0.15 mm. The second insulator 24b covers the side surfaces of the teeth (tooth portions 22a described later) of the stator core 2a.

[0040] FIG. 4 is a plan view schematically showing the structure of the stator core 2a.

[0041] The stator core 2a has at least one yoke portion 21a and at least two teeth portions 22a. The stator core 2a is made up of a plurality of core portions 21. Therefore, each core portion 21 has a yoke portion 21a and teeth portions 22a.

[0042] In the example shown in FIG. 4, the stator core 2a is made up of nine core portions 21.

[0043] However, the stator core 2a does not have to be divided into a plurality of core portions 21. In this case, the stator core 2a may be made up of a plurality of core portions 21 integrated as a single member. For example, the stator core 2a may be formed by laminating a plurality of annular materials (for example, electromagnetic steel sheets).

[0044] The area surrounded by the two yoke portions 21a and the two tooth portions 22a is a slot portion 26. In the stator core 2a, the slot portions 26 are provided at equal intervals in the circumferential direction. In the example shown in Fig. 4, nine slot portions 26 are provided in the stator core 2a.

[0045] As shown in Fig. 4, the stator core 2a has a plurality of teeth 22a, and the teeth 22a are adjacent to each other via slots 26. Therefore, the teeth 22a and the slots 26 are arranged alternately in the circumferential direction. The arrangement pitch of the teeth 22a in the circumferential direction (i.e., the width of the slots 26 in the circumferential direction) is equal. In other words, the teeth 22a are positioned radially.

[0046] In this embodiment, the stator 2 has N split core portions 25a (N is a natural number of 2 or more). Therefore, the stator 2 has N tooth portions 22a. In the example shown in FIG. 1, the stator 2 has nine split core portions 25a. Therefore, in the example shown in FIG. 1, the stator 2 has nine tooth portions 22a.

[0047] FIG. 5 is a cross-sectional view that schematically shows the structure of the core segment 25a. Each split core portion 25a has a yoke portion 21a, teeth portions 22a located radially inside yoke portion 21a, coil 27, first insulator 24a that insulates stator core 2a, and second insulator 24b that insulates stator core 2a. In this embodiment, teeth portions 22a are integrated with yoke portion 21a as a single member, but teeth portions 22a formed separately from yoke portion 21a may also be attached to yoke portion 21a.

[0048] The coil 27 is wound around the stator core 2a via the first insulator 24a and the second insulator 24b. Specifically, the coil 27 is wound around the teeth 22a. When a current flows through the coil 27, a rotating magnetic field is generated from the coil 27.

[0049] The coil 27 is, for example, a magnet wire. For example, the stator 2 is three-phase, and the coil 27 is connected, for example, in a Y connection (also called a star connection) or a delta connection. The number of turns and wire diameter of the coil 27 are determined depending on the rotation speed, torque, voltage specifications, and cross-sectional area of ​​the slot portion 26 of the motor 1. The wire diameter of the coil 27 is, for example, 1.0 mm. The coil 27 is wound, for example, 80 turns around each tooth portion 22a of the stator core 2a. However, the wire diameter and number of turns of the coil 27 are not limited to these examples.

[0050] The winding method of the coil 27 is, for example, concentrated winding. For example, the coil 27 can be wound around the core portion 21 in a state before the core portion 21 is arranged in an annular shape (for example, in a state in which the core portion 21 is arranged linearly). The core portion 21 (i.e., the split core portion 25a) around which the coil 27 is wound is folded into an annular shape and fixed by welding or the like.

[0051] Coil 27 may be attached to each tooth portion 22a of stator core 2a in a distributed winding manner instead of in a concentrated winding manner.

[0052] FIG. 6 is a plan view schematically showing the structure of the iron core portion 21. As shown in FIG. FIG. 7 is a perspective view schematically showing the structure of the iron core portion 21. As shown in FIG.

[0053] Yoke portion 21a extends in the circumferential direction, and teeth portion 22a extends radially inward of stator core 2a (in FIG. 6, the -y direction). In other words, teeth portion 22a protrudes from yoke portion 21a toward axis A1.

[0054] As shown in Figures 6 and 7, each tooth 22a has a main body 221a, a tooth tip 222a, and a tooth tip surface 223a. The tooth tip 222a is provided at the tip of the tooth 22a in the radial direction (specifically, at the end of the main body 221a). In the example shown in Figures 6 and 7, the main body 221a has a uniform width along the radial direction. The tooth tip 222a extends in the circumferential direction and is formed to widen in the circumferential direction.

[0055] In the motor 1, the tooth tip surfaces 223a face the rotor 3. Specifically, in the motor 1, the tooth tip surfaces 223a are surfaces of the tooth tips 222a that face the rotor 3.

[0056] As shown in FIGS. 5 to 7, the core portion 21 (for example, the yoke portion 21a) is provided with a fixing hole 24c for fixing the first insulator 24a.

[0057] 7, the core portion 21 is made up of at least one sheet 28 (also called a plate). In this embodiment, the core portion 21 is formed by stacking a plurality of sheets 28 in the axial direction (i.e., the z-axis direction).

[0058] Sheet 28 is formed into a predetermined shape by press working (specifically, punching). Sheet 28 is, for example, an electromagnetic steel sheet. When an electromagnetic steel sheet is used as sheet 28, sheet 28 has a thickness of, for example, 0.01 mm to 0.7 mm. In this embodiment, sheet 28 has a thickness of 0.35 mm. Sheet 28 is fixed to adjacent other sheets 28 by crimping portions 24d.

[0059] The structure of the rotor 3 will be described below. FIG. 8 is a cross-sectional view schematically showing the structure of the rotor 3. As shown in FIG.

[0060] The rotor 3 has a rotor core 31, a shaft 32, at least one permanent magnet 33, at least one magnet insertion hole 34, at least one flux barrier 35, at least one air hole 36, and at least one slit 38. The rotor 3 is rotatable about an axis A1. The rotor 3 is rotatably disposed inside the stator 2. The axis A1 is the rotation center of the rotor 3 and is also the axis of the shaft 32.

[0061] In this embodiment, the rotor 3 is a permanent magnet embedded rotor. The rotor core 31 has a plurality of magnet insertion holes 34 arranged in the circumferential direction of the rotor 3. The magnet insertion holes 34 are gaps in which permanent magnets 33 are placed. One permanent magnet 33 is placed in each magnet insertion hole 34. However, multiple permanent magnets 33 may be placed in each magnet insertion hole 34. The permanent magnets 33 placed in the magnet insertion holes 34 are magnetized in the radial direction of the rotor 3 (i.e., in a direction perpendicular to the axis A1). The number of magnet insertion holes 34 corresponds to the number of magnetic poles of the rotor 3. The positional relationship of each magnetic pole is the same. In this embodiment, the number of magnetic poles of the rotor 3 is six. However, the number of magnetic poles of the rotor 3 may be two or more.

[0062] The permanent magnet 33 may be, for example, a rare earth magnet containing neodymium (Nd), iron (Fe), and boron (B) (hereinafter referred to as an "Nd--Fe--B permanent magnet").

[0063] The coercive force of Nd-Fe-B permanent magnets tends to decrease with temperature. For example, when a motor using Nd rare earth magnets is used in a high-temperature atmosphere of 100°C or higher, such as a compressor, the coercive force of the magnet deteriorates by approximately -0.5 to -0.6% / ΔK depending on the temperature, making it necessary to add Dy (dysprosium) to increase the coercive force. Coercive force improves in roughly proportion to the Dy content. In a typical compressor, the upper ambient temperature limit for the motor is around 150°C, and the motor is used within a temperature rise range of approximately 130°C for every 20°C. For example, a temperature coefficient of -0.5% / ΔK results in a 65% decrease in coercive force.

[0064] To prevent demagnetization under the maximum load of the compressor, a coercive force of approximately 1100 to 1500 A / m is required. To ensure coercive force at an ambient temperature of 150°C, the room temperature coercive force must be designed to be approximately 1800 to 2300 A / m.

[0065] When no Dy element is added to an Nd-Fe-B permanent magnet, its room-temperature coercivity is approximately 1800 A / m. To achieve a coercivity of approximately 2300 kA / m, approximately 2 wt% Dy element must be added. However, although adding Dy improves coercivity characteristics, it also reduces remanence. A decrease in remanence reduces the motor's magnet torque and increases the current flow, resulting in increased copper loss. Therefore, when considering motor efficiency, it is desirable to reduce the amount of Dy added.

[0066] The rotor core 31 is formed by laminating a plurality of electromagnetic steel sheets. The thickness of each electromagnetic steel sheet of the rotor core 31 is, for example, 0.1 mm to 0.7 mm. In this embodiment, the thickness of each electromagnetic steel sheet of the rotor core 31 is 0.35 mm. The electromagnetic steel sheets of the rotor core 31 are fixed to adjacent electromagnetic steel sheets by caulking.

[0067] At least one slit 38 is formed outside the magnet insertion hole 34 in the radial direction of the rotor 3. In this embodiment, a plurality of slits 38 are formed outside the magnet insertion hole 34 in the radial direction of the rotor 3. Each slit 38 is long in the radial direction.

[0068] The shaft 32 is connected to the rotor core 31. For example, the shaft 32 is fixed to an axial hole 37 formed in the rotor core 31 by a fixing method such as shrink fitting or press fitting. As a result, the rotational energy generated by the rotation of the rotor core 31 is transmitted to the shaft 32.

[0069] The flux barriers 35 are formed at positions adjacent to the magnet insertion holes 34 in the circumferential direction of the rotor 3. In other words, each flux barrier 35 is adjacent to the end of each magnet insertion hole 34 in the longitudinal direction of the magnet insertion hole 34. The flux barriers 35 reduce leakage magnetic flux. To prevent short-circuiting of magnetic flux between adjacent magnetic poles, it is desirable that the width of the thin-walled portion between the flux barrier 35 and the outer peripheral surface of the rotor core 31 be short. The width of the thin-walled portion between the flux barrier 35 and the outer peripheral surface of the rotor core 31 is, for example, 0.35 mm. The air holes 36 are through holes. For example, when the motor 1 is used in a compressor, refrigerant can pass through the air holes 36.

[0070] The structure of the teeth portion 22a will be specifically described. FIG. 9 is a diagram showing the structure of the teeth portion 22a. In the xy plane, when the angle formed by two straight lines L1 passing through both ends P1 of the teeth tip surfaces 223a and the center of rotation of the rotor 3 is θ1 [degrees], the stator 2 satisfies 0.75≦(θ1×N) / 360≦0.97.

[0071] In this embodiment, N=9, but N may be any natural number equal to or greater than 2.

[0072] That is, in the xy plane, the percentage α [%] of the circumference of a circle passing through the tooth tip surfaces 223a that is occupied by the tooth tip surfaces 223a is between 75% and 97%. In the present application, this percentage α is referred to as the opening angle percentage α. The circle passing through the tooth tip surfaces 223a is, for example, the circle indicated by the dashed line R1 in FIG. 4.

[0073] Variation 1. FIG. 10 is a cross-sectional view schematically showing another example of the motor 1. As shown in FIG. In the axial direction of the rotor 3, the rotor 3 is longer than the stator 2. In this case, the rotor 3 only needs to be longer than the stator core 2a.

[0074] Variation 2. FIG. 11 is a cross-sectional view schematically showing still another example of the motor 1. As shown in FIG. FIG. 12 is a plan view schematically illustrating an example of the metal member 39. As shown in FIG. In the second modification, the rotor 3 has at least one metal member 39. The metal member 39 is fixed to an end of the rotor core 31 in the axial direction of the rotor 3.

[0075] 11 and 12, the rotor 3 has two metal members 39, and the metal members 39 are fixed to both ends of the rotor core 31. It is desirable that the metal members 39 be a single structure. This allows the cost of the metal members 39 to be reduced.

[0076] In the xy plane, the surface area of ​​each metal member 39 is larger than the surface area of ​​the rotor core 31 (specifically, the surface of the rotor core 31 facing the metal member 39).

[0077] Variation 3. FIG. 13 is a diagram showing another example of the rotor 3. In FIG. The rotor 3 may have a rotor core 31a shown in FIG. 13 instead of the rotor core 31. The rotor core 31a shown in FIG. 13 has a plurality of different radii in the xy plane. Specifically, the radius of the rotor core 31a is maximum at the magnetic pole center of the rotor 3 and minimum at the inter-pole portion of the rotor 3. In the example shown in FIG. 13, the outer diameter of the rotor core 31a is maximum at the magnetic pole center of the rotor 3 and minimum at the inter-pole portion of the rotor 3. In the xy plane shown in FIG. 13, the magnetic pole center of the rotor 3 is located on a line passing through the center of each permanent magnet 33 and the axis A1. In the xy plane shown in FIG. 13, the inter-pole portion of the rotor 3 is located on a line passing through the axis A1 and a point between adjacent permanent magnets 33.

[0078] The advantages of the stator 2 according to the first embodiment will be described below. Fig. 14 is a graph showing the relationship between the rotation angle of the rotor and the internal pressure in the cylinder. In the example shown in Fig. 14, the solid line B1 corresponds to a motor with a large torque ripple, and the dashed line B2 corresponds to a motor with a small torque ripple. Normally, when a compressor starts compressing a refrigerant, the internal pressure of the cylinder increases. When the internal pressure reaches the target discharge pressure that satisfies the required capacity, the refrigerant pushes aside the valve, opening the valve. This connects the cylinder to the discharge muffler, and the refrigerant is discharged from the discharge pipe at the target discharge pressure.

[0079] However, if there is a time lag between when the internal pressure of the cylinder reaches the target discharge pressure and when the valve is fully opened, the internal pressure of the cylinder may exceed the target discharge pressure, a phenomenon referred to in this application as "pressure overshoot."

[0080] When pressure overshoot occurs, refrigerants containing substances that undergo disproportionation reactions, such as 1,1,2-trifluoroethylene and 1,2-difluoroethylene, undergo a sudden volume expansion due to a chain reaction of disproportionation reactions, making the cylinders in the compressor more susceptible to failure. Therefore, it is desirable to suppress pressure overshoot as much as possible.

[0081] Typically, in a compressor, the higher the rotation speed of the motor, the shorter the compression cycle of the refrigerant, and the greater the impact of a delay in the opening of the valve. In other words, the higher the rotation speed of the motor, the more likely it is that a pressure overshoot will occur.

[0082] Normally, torque ripple occurs when a motor is running, causing the motor's rotation speed to fluctuate. The higher the instantaneous rotation speed, the higher the instantaneous internal pressure of the cylinder, making the cylinder more susceptible to failure.

[0083] FIG. 15 is a graph showing the relationship between the opening angle rate α [%] and the torque ripple rate [%] when the motor is driven at a torque equal to or less than the rated torque. FIG. 16 is a diagram showing the magnetic flux density in stator core 2a when the motor is driven at a torque equal to or less than the rated torque. FIG. 17 is a diagram showing the magnetic flux density in stator core 2a when the motor is driven with a torque greater than the rated torque.

[0084] As shown in Figure 15, when the motor is driven at or below the rated torque, the larger the angle θ1 shown in Figure 9, the smaller the torque ripple rate when the motor is driven. The torque ripple rate is the ratio of the difference between the maximum torque and the minimum torque to the time-averaged torque. The smaller the torque ripple rate, the less fluctuation in the motor's rotational speed while the motor is running, and the less likely pressure overshoot will occur. As shown in Figure 16, when the torque load is small, the impact of magnetic saturation on each tooth is small. In contrast, as shown in Figure 17, when the torque load is large, magnetic saturation on each tooth increases. For example, when the torque load on the motor inside a compressor is large, the internal pressure of the cylinder increases, making the compressor more likely to malfunction due to a disproportionation reaction of the refrigerant.

[0085] Specifically, the angle θ1 affects the magnetic attraction force generated between the stator and the rotor, which in turn affects the torque ripple rate.

[0086] FIG. 18 is a graph showing the relationship between the opening angle rate α [%] and the torque ripple rate [%] when the motor 1 is driven with a torque greater than the rated torque. 18, when the opening angle ratio α is 75% or more, the torque ripple rate can be effectively reduced. That is, when 0.75≦(θ1×N) / 360, the torque ripple rate can be effectively reduced.

[0087] When the opening angle ratio α is 84% ​​or more, the torque ripple rate can be reduced more effectively. That is, when 0.84≦(θ1×N) / 360, the torque ripple rate can be reduced more effectively.

[0088] When the opening angle ratio α exceeds 97%, the torque ripple ratio increases rapidly. That is, when (θ1×N) / 360>0.97, the torque ripple ratio increases rapidly.

[0089] Therefore, it is desirable that the opening angle ratio α is 75% or more and 97% or less. In other words, it is desirable that the stator 2 satisfy 0.75≦(θ1×N) / 360≦0.97. This effectively reduces the torque ripple rate, and as a result, it becomes possible to make the compressor less susceptible to breakdowns.

[0090] It is more desirable that the opening angle ratio α be 84% or more and 97% or less. In other words, it is more desirable that the stator 2 be 0.84≦(θ1×N) / 360≦0.97. This makes it possible to more effectively reduce the torque ripple rate, and as a result, it becomes possible to make the compressor less susceptible to breakdowns.

[0091] Furthermore, it is more desirable that the opening angle ratio α be 87.5% or more and 92.5% or less. In other words, it is more desirable that the stator 2 be 0.875≦(θ1×N) / 360≦0.925. This makes it possible to more effectively reduce the torque ripple rate, thereby making it more unlikely for the compressor to malfunction.

[0092] When the opening angle ratio α is 90%, the torque ripple rate is minimum. Therefore, when the stator 2 satisfies (θ1×N) / 360=0.9, the torque ripple rate is minimum. In this case, the compressor is less likely to malfunction.

[0093] The opening angle ratio α may be 87.5% or more and 97% or less. In other words, when the stator 2 satisfies 0.875≦(θ1×N) / 360≦0.97, the torque ripple rate can be effectively reduced, and as a result, the compressor can be made less susceptible to breakdowns.

[0094] The opening angle ratio α may be 87.5% or more and 92.5% or less. In other words, when the stator 2 satisfies 0.875≦(θ1×N) / 360≦0.925, the torque ripple rate can be effectively reduced, and as a result, the compressor can be made less susceptible to breakdowns.

[0095] The opening angle ratio α may be 84% or more and 92.5% or less. In other words, when the stator 2 satisfies 0.84≦(θ1×N) / 360≦0.925, the torque ripple rate can be effectively reduced, and as a result, the compressor can be made less susceptible to breakdowns.

[0096] When coil 27 is attached to each tooth 22a of stator core 2a in a distributed winding manner, the magnetic flux from coil 27 is more widely dispersed in stator 2 than in concentrated winding. This reduces the fluctuations in the magnetic attraction force generated between rotor 3 and stator 2 when rotor 3 rotates, thereby reducing the torque ripple rate.

[0097] If the motor 1 has an inverter that operates using PWM control, the waveform of the inverter voltage can be finely adjusted, which allows the torque waveform of the motor 1 caused by the inverter voltage to be controlled and the torque ripple rate to be reduced.

[0098] When the rotor 3 is longer than the stator 2 in the axial direction of the rotor 3, the moment of inertia of the rotor 3 can be increased. This makes it possible to suppress the occurrence of pressure overshoot. Furthermore, when the stator 2 is shorter than the rotor 3 in the axial direction of the rotor 3, the motor 1 can be made smaller. Therefore, the compressor having the motor 1 can be made smaller.

[0099] When the rotor 3 has at least one metal member 39, it is possible to increase the moment of inertia of the rotor 3. This makes it possible to suppress the occurrence of pressure overshoot.

[0100] When the rotor 3 has at least one metal member 39, it is desirable that the surface area of ​​each metal member 39 in the xy plane be larger than the surface area of ​​the rotor core 31 (specifically, the surface of the rotor core 31 facing the metal member 39). This can further increase the moment of inertia of the rotor 3. This can effectively suppress the occurrence of pressure overshoot.

[0101] When the radius of the rotor core 31a is maximum at the magnetic pole center of the rotor 3 and minimum at the inter-pole portion of the rotor 3, the magnetic flux density on the outer circumferential surface of the rotor 3 is maximum at the magnetic pole center and minimum at the inter-pole portion. In other words, the magnetic flux density on the outer circumferential surface of the rotor 3 decreases as it approaches the inter-pole portion from the magnetic pole center. This causes the waveform of the induced voltage in the motor 1 to approach a sine wave, reducing the torque ripple rate. As a result, the occurrence of pressure overshoot can be suppressed.

[0102] Embodiment 2 A compressor 6 according to a second embodiment of the present invention will be described. FIG. 19 is a cross-sectional view that schematically shows the structure of a compressor 6 according to the second embodiment.

[0103] Compressor 6 has motor 1 as an electric element, a sealed container 61 as a housing, and a compression mechanism 62 as a compression element (also referred to as a compression device). Compressor 6 is used with the refrigerant described in the first embodiment, that is, a refrigerant containing a substance that has the property of causing a disproportionation reaction. This refrigerant may be provided in compressor 6 in advance. In this embodiment, compressor 6 is a rotary compressor. However, compressor 6 is not limited to a rotary compressor.

[0104] The motor 1 in the compressor 6 is the motor 1 described in the first embodiment. The motor 1 drives the compression mechanism 62. In this embodiment, the motor 1 is an embedded permanent magnet motor, but is not limited to this.

[0105] The sealed container 61 covers the motor 1 and the compression mechanism 62. At the bottom of the sealed container 61, refrigeration oil for lubricating the sliding parts of the compression mechanism 62 is stored.

[0106] The compressor 6 further includes a glass terminal 63 fixed to the sealed container 61, an accumulator 64, a suction pipe 65 for drawing in the refrigerant, and a discharge pipe 66 for ejecting the refrigerant.

[0107] The suction pipe 65 and the discharge pipe 66 are fixed to the sealed container 61 .

[0108] The compression mechanism 62 is disposed inside the sealed container 61. In this embodiment, the compression mechanism 62 is disposed in the lower part of the sealed container 61.

[0109] The compression mechanism 62 includes a cylinder 62a, a piston 62b, an upper frame 62c (first frame), a lower frame 62d (second frame), and a plurality of mufflers 62e attached to the upper frame 62c and the lower frame 62d, respectively. The compression mechanism 62 further includes a vane that divides the interior of the cylinder 62a into an intake side and a compression side.

[0110] The compression mechanism 62 is driven by the motor 1. The compression mechanism 62 compresses the refrigerant.

[0111] The motor 1 is disposed in the upper part of the sealed container 61. Specifically, the motor 1 is located between the discharge pipe 66 and the compression mechanism 62. In other words, the motor 1 is provided above the compression mechanism 62.

[0112] The stator 2 of the motor 1 is fixed in the sealed container 61 by a fixing method such as press fitting or shrink fitting. Instead of press fitting or shrink fitting, the stator 2 may be directly attached to the sealed container 61 by welding.

[0113] Electric power is supplied to the coils of the stator 2 of the motor 1 (for example, the coils 27 shown in FIG. 1) via glass terminals 63.

[0114] The rotor of the motor 1 (specifically, the shaft 32 of the rotor 3) is rotatably held by the upper frame 62c and the lower frame 62d via bearings provided on each of the upper frame 62c and the lower frame 62d.

[0115] The shaft 32 is inserted through the piston 62b. The shaft 32 is rotatably inserted through the upper frame 62c and the lower frame 62d. The upper frame 62c is provided with a valve that prevents backflow of the refrigerant. Specifically, this valve is located between the upper frame 62c and the muffler 62e. The upper frame 62c and the lower frame 62d close the end face of the cylinder 62a. The accumulator 64 supplies the refrigerant to the cylinder 62a through a suction pipe 65.

[0116] Next, the operation of the compressor 6 will be described. The refrigerant supplied from the accumulator 64 enters the cylinder 62a through the suction pipe 65 fixed to the sealed container 61. When the motor 1 rotates, the piston 62b fitted to the shaft 32 rotates in the cylinder 62a. This causes the refrigerant to be compressed in the cylinder 62a.

[0117] The refrigerant passes through the muffler 62e and rises inside the sealed container 61. The refrigerant is compressed in the cylinder 62a, and when the internal pressure of the cylinder 62a reaches a certain level or higher, a valve provided in the upper frame 62c opens and the compressed refrigerant is discharged from the discharge pipe 66. In this way, the compressed refrigerant is supplied to the high-pressure side of the refrigeration cycle through the discharge pipe 66. When the internal pressure of the cylinder 62a falls below a certain level, the valve closes and the flow of refrigerant is stopped.

[0118] The compressor 6 according to the second embodiment has the motor 1 described in the first embodiment, and therefore the compressor 6 can be made less susceptible to breakdowns.

[0119] Embodiment 3 A refrigeration air conditioning device 7 as an air conditioner having a compressor 6 according to the second embodiment of the present invention will be described. FIG. 20 is a diagram schematically showing the configuration of a refrigeration air conditioning device 7 according to the third embodiment.

[0120] The refrigeration air conditioning device 7 is capable of, for example, cooling and heating operation. The refrigerant circuit diagram shown in Figure 20 is an example of a refrigerant circuit diagram of an air conditioner capable of cooling operation.

[0121] The refrigeration air conditioning device 7 according to the third embodiment has an outdoor unit 71, an indoor unit 72, and refrigerant piping 73 connecting the outdoor unit 71 and the indoor unit 72.

[0122] The outdoor unit 71 has a compressor 6, a condenser 74 as a heat exchanger, a throttling device 75, and an outdoor fan 76 (first fan). The condenser 74 condenses the refrigerant compressed by the compressor 6. The throttling device 75 reduces the pressure of the refrigerant condensed by the condenser 74 to adjust the flow rate of the refrigerant. The throttling device 75 is also called a pressure reducing device.

[0123] The indoor unit 72 has an evaporator 77 as a heat exchanger, and an indoor fan 78 (second fan). The evaporator 77 evaporates the refrigerant decompressed by the expansion device 75, and cools the indoor air.

[0124] The basic operation of the cooling operation of the refrigeration and air conditioning unit 7 will be described below. In cooling operation, the refrigerant is compressed by the compressor 6 and flows into the condenser 74. The condenser 74 condenses the refrigerant, and the condensed refrigerant flows into the throttling device 75. The refrigerant is decompressed by the throttling device 75, and the decompressed refrigerant flows into the evaporator 77. The refrigerant evaporates in the evaporator 77, and the refrigerant (specifically, refrigerant gas) flows back into the compressor 6 of the outdoor unit 71. When the outdoor fan 76 sends air to the condenser 74, heat is transferred between the refrigerant and the air. Similarly, when the indoor fan 78 sends air to the evaporator 77, heat is transferred between the refrigerant and the air.

[0125] The configuration and operation of the refrigeration and air conditioning device 7 described above are merely examples, and the present invention is not limited to the above example.

[0126] The refrigeration and air conditioning device 7 according to the third embodiment has the advantages described in the first and second embodiments.

[0127] Since the refrigeration air conditioning device 7 according to the third embodiment has the compressor 6, the occurrence of breakdowns in the refrigeration air conditioning device 7 can be reduced.

[0128] As explained above, the preferred embodiment has been specifically explained, but it is obvious that a person skilled in the art can adopt various modifications based on the basic technical idea and teaching of the present invention.

[0129] The features of the above-described embodiments and modifications can be combined with each other as appropriate. [Explanation of symbols]

[0130] 1 motor, 2 stator, 3 rotor, 6 compressor, 7 refrigeration and air conditioning device, 21a yoke portion, 22a teeth portion, 27 coil, 31 rotor core, 33 permanent magnet, 39 metal member, 61 sealed container, 62 compression mechanism, 74 condenser, 77 evaporator, 103 inverter, 223a teeth tip surface.

Claims

1. A stator disposed on the outside of a rotor of a motor disposed in a compressor used with a refrigerant containing a substance that has a property of undergoing a disproportionation reaction, a stator core having a plurality of sheets stacked in an axial direction of the rotor; The stator core is composed of a plurality of core portions that are divided into annular portions and arranged in a circumferential direction, and includes a yoke portion and N teeth portions. Each of the N teeth portions has a teeth tip surface facing the rotor, The curvature of the tip surface of the teeth is constant in a plane perpendicular to the axial direction, When the angle between two straight lines passing through both ends of the tooth tip surface and the rotation center of the rotor in a plane perpendicular to the axial direction is θ1 [degrees], Each of the plurality of sheets is such that 0.75≦(θ1×N) / 360≦0.97 A stator that satisfies the above requirements.

2. The stator according to claim 1 , wherein 0.84≦(θ1×N) / 360≦0.97 is satisfied.

3. 2. The stator according to claim 1, wherein 0.75≦(θ1×N) / 360≦0.925 is satisfied.

4. The stator according to claim 1 , further comprising a coil attached to the N teeth portions in a distributed winding manner.

5. 5. The stator according to claim 1, wherein the substance capable of causing a disproportionation reaction is 1,1,2-trifluoroethylene.

6. 5. The stator according to claim 1, wherein the substance capable of causing a disproportionation reaction is 1,2-difluoroethylene.

7. A stator according to any one of claims 1 to 6; The rotor is disposed inside the stator; A motor comprising:

8. 8. The motor of claim 7, further comprising an inverter operating under pulse width modulation control to power said stator.

9. 9. The motor according to claim 7, wherein the rotor is longer than the stator in an axial direction of the rotor.

10. 10. The motor according to claim 7, wherein the rotor is a permanent magnet embedded rotor having a permanent magnet.

11. the rotor has a rotor core and a metal member fixed to an end of the rotor core in an axial direction of the rotor, In the plane perpendicular to the axial direction of the rotor, the surface area of ​​the metal member is larger than the surface area of ​​the rotor core. A motor according to any one of claims 7 to 10.

12. The rotor has a rotor core, 12. The motor according to claim 7, wherein an outer diameter of the rotor core is maximum at a magnetic pole center of the rotor and is minimum at an inter-pole portion of the rotor.

13. A sealed container; A compression device disposed within the sealed container; A motor according to any one of claims 7 to 12 for driving the compression device; A compressor comprising:

14. A compressor according to claim 13; Heat exchanger and An air conditioner equipped with:

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