Motor for compressor, compressor, and refrigeration device

Abstract

When a first position (P1) is defined as a position in the circumferential direction where a magnetic flux resulting from a magnet (33) in a rotor (31) reaches the maximum, and the magnetic pole center line (CL) is defined as a straight line virtually drawn so as to pass through the first position (P1) and a rotational axis (O), at least a portion of the magnet (33) or a rotor core (32) is configured asymmetrically with respect to a magnetic pole center line (CL) as viewed from the axial direction. When a second position (P2) is defined as a position in the circumferential direction where magnetic resistance in the rotor (31) reaches the maximum, the second position (P2) is shifted toward the backward travel side in the rotation direction of the rotor (31) with respect to the first position (P1).

Description

Motor for Compressor, Compressor, and Refrigeration Device

[0001] The present disclosure relates to a motor for a compressor, a compressor, and a refrigeration device.

[0002] The output torque of a motor is composed of a magnet torque and a reluctance torque. Usually, since the current phase at which the magnet torque is maximum and the current phase at which the reluctance torque is maximum are different, the output torque of the motor is lower than the sum of the peak value of the magnet torque and the peak value of the reluctance torque.

[0003] Patent Document 1 discloses an electric motor provided with a rotor having a permanent magnet type rotor part having a plurality of permanent magnets and a reluctance type rotor part having a plurality of salient pole parts. By providing a deviation angle between the permanent magnet rotor part and the reluctance type rotor part and aligning the current phases at which each rotor part generates maximum torque, the output torque is increased.

[0004] Japanese Patent Application Laid-Open No. 2003-18777

[0005] However, in the electric motor of Patent Document 1, since the current phases for generating the maximum torque are aligned in the permanent magnet type rotor part and the reluctance type rotor part, the torque becomes large at the aligned current phase, but when deviating from the current phase, the torque becomes small. That is, the electric motor of Patent Document 1 has a problem that the output torque decreases when operating outside the current phase at which the output torque is maximum.

[0006] An object of the present disclosure is to provide a motor for a compressor that can suppress a decrease in output torque over a wide range of current phases.

[0007] A first aspect of this disclosure is a compressor motor (20) comprising a rotor (31) that rotates in one direction about a rotation axis (O), and a stator (21) arranged radially opposite to the rotor (31). The rotor (31) comprises a rotor core (32) and magnets (33), with alternating polarities in the circumferential direction. The stator (21) comprises a stator core (22) and windings (23). When the circumferential position on the rotor (31) where the magnetic flux from the magnets (33) is maximum is defined as a first position (P1), and a hypothetical straight line drawn passing through the first position (P1) and the rotation axis (O) is defined as the magnetic pole centerline (CL), at least a portion of the magnets (33) or the rotor core (32) is configured asymmetrically with respect to the magnetic pole centerline (CL) when viewed from the axial direction. The circumferential position where the magnetic resistance of the rotor (31) is maximum is defined as the second position (P2), and the second position (P2) is shifted backward in the rotational direction of the rotor (31) relative to the first position (P1).

[0008] In the first embodiment, in the circumferential direction of the rotor (31), the second position (P2) where the magnetic resistance is maximum is shifted backward in the rotational direction relative to the first position (P1) where the magnetic flux from the magnet (33) is maximum. As a result, the difference between the current phase at which the magnet torque is maximum and the current phase at which the reluctance torque is maximum becomes large, and the decrease in output torque can be suppressed over a wide range of current phases.

[0009] A second aspect of the present disclosure is that, in the first aspect, the difference between the phase of the AC voltage induced in the winding (23) by the magnet (33) and the phase of the AC current supplied to the winding (23) is defined as a phase difference, and when the phase difference is such that the magnet torque generated by the magnet (33) and the AC current becomes zero and the direction of the magnetic flux due to the AC current is opposite to the direction of the magnetic flux due to the magnet (33), the reluctance torque generated by the rotor core (32) and the AC current becomes a positive value.

[0010] In the second embodiment, even in the region where the magnet torque is zero, i.e., the current phase is large, the reluctance torque is positive, so the output torque can be increased in the region where the current phase is large.

[0011] A third aspect of the present disclosure, in the first or second aspect, the rotor (31) comprises a first rotor portion (31a) having a rotor core (32) and a magnet (33), and a second rotor portion (31b) arranged axially adjacent to the first rotor portion (31a), having a rotor core (32) but not a magnet (33). When the circumferential position in the first rotor portion (31a) where the magnetic flux due to the magnet (33) is maximum is defined as a third position (P3), and the circumferential position in the second rotor portion (31b) where the magnetic resistance is maximum is defined as a fourth position (P4), the fourth position (P4) is shifted backward in the rotational direction of the rotor (31) relative to the third position (P3).

[0012] In the third embodiment, the difference between the current phase at which the magnet torque generated by the first rotor (31a) is maximum and the current phase at which the reluctance torque generated by the second rotor (31b) is maximum becomes large, so the decrease in output torque can be suppressed over a wide range of current phases.

[0013] A fourth aspect of the present disclosure, in the third aspect, is that, viewed from the axial direction, the shape of the rotor core (32) of the first rotor portion (31a) is substantially the same as the shape of the rotor core (32) of the second rotor portion (31b), and the rotor core (32) of the second rotor portion (31b) is positioned offset to the rearward side in the rotational direction of the rotor (31) relative to the rotor core (32) of the first rotor portion (31a).

[0014] In the fourth embodiment, since the rotor core (32) of the first rotor section (31a) and the rotor core (32) of the second rotor section (31b) have the same shape, the manufacturing of the rotor (31) becomes easier.

[0015] A fifth aspect of the present disclosure, in the third or fourth aspect, the first rotor portion (31a) has a region that is not radially opposed to the stator (21).

[0016] In the fifth embodiment, the magnetic torque generated by the first rotor section (31a) can be increased, thereby increasing the output torque.

[0017] A sixth aspect of the present disclosure is that in any one of the first to fifth aspects, at least a portion of the magnet (33) is configured asymmetrically with respect to the magnetic pole center line (CL).

[0018] In the sixth embodiment, even when the rotor (31) has a single structure, the decrease in output torque can be suppressed over a wide range of current phases.

[0019] A seventh aspect of this disclosure is a compressor comprising a compressor motor (20) according to any one of the first to sixth aspects.

[0020] In the seventh embodiment, a compressor motor (20) capable of suppressing a decrease in output torque over a wide range of current phases is used, thereby improving the energy efficiency of the compressor (10).

[0021] An eighth aspect of this disclosure is a refrigeration system comprising a compressor (10) according to the seventh aspect.

[0022] In the eighth embodiment, since an energy-efficient compressor (10) is used, the power consumption of the refrigeration system (1) can be reduced.

[0023] Figure 1 is a longitudinal cross-sectional view showing the basic configuration of the motor. Figure 2 is a transverse cross-sectional view of the stator in the motor shown in Figure 1. Figure 3 is a schematic diagram showing the general longitudinal cross-sectional configuration of the motor of Embodiment 1. Figure 4A is a schematic diagram showing the general cross-sectional configuration of the first rotor section in the motor of Embodiment 1. Figure 4B is a schematic diagram showing the general cross-sectional configuration of the second rotor section in the motor of Embodiment 1. Figure 5A is a schematic diagram showing the configuration of a measurement environment for identifying the circumferential position in the rotor where the magnetic flux from the magnets is maximum. Figure 5B is a schematic diagram showing the results measured using the measurement environment shown in Figure 5A. Figure 5C is a schematic diagram showing the circumferential position in the rotor where the magnetic flux from the magnets is maximum, identified from the measurement results shown in Figure 5B. Figure 6A is a schematic diagram showing the configuration of a measurement environment for identifying the circumferential position in the rotor where the magnetic resistance is maximum. Figure 6B is a schematic diagram showing the results measured using the measurement environment shown in Figure 6A. Figure 6C is a schematic diagram showing the circumferential position in the rotor where the magnetic resistance is maximum, as determined from the measurement results shown in Figure 6B. Figure 7A is a diagram showing the torque characteristics of the motor of Embodiment 1 when the circumferential position in the first rotor section where the magnetic flux due to the magnet is maximum and the circumferential position in the second rotor section where the magnetic resistance is maximum are not shifted. Figure 7B is a diagram showing the torque characteristics of the motor of Embodiment 1. Figure 7C is a diagram showing a comparison between the torque characteristics shown in Figure 7A and the torque characteristics shown in Figure 7B. Figure 8A is a diagram showing the torque characteristics in the range of small current phase when a large current is passed through the motor of Embodiment 1. Figure 8B is a diagram showing the torque characteristics in the range of small current phase when a small current is passed through the motor of Embodiment 1. Figure 9A is a schematic diagram showing the general cross-sectional configuration of the rotor in the motor of Modification 1 of Embodiment 1 when the circumferential position in the magnet is maximum and the circumferential position in the magnetic resistance is maximum are not shifted. Figure 9B is a schematic diagram showing the general cross-sectional configuration of the rotor in the motor of Modification 1 of Embodiment 1. Figure 10A is a diagram showing the torque characteristics of the motor of Modification 1 of Embodiment 1 when the circumferential position where the magnetic flux due to the magnet is maximum and the circumferential position where the magnetic resistance is maximum are not shifted. Figure 10B is a diagram showing the torque characteristics of the motor of Modification 1 of Embodiment 1.Figure 10C is a diagram comparing the torque characteristics shown in Figure 10A with those shown in Figure 10B. Figure 11 is a schematic diagram showing the general vertical cross-sectional configuration of the motor of the modified example 2 of Embodiment 1. Figure 12A is a diagram showing the torque characteristics of the motor of the modified example 2 of Embodiment 1 when the circumferential position where the magnetic flux from the magnet in the first rotor is maximum and the circumferential position where the magnetic resistance in the second rotor is maximum are not shifted. Figure 12B is a diagram showing the torque characteristics of the motor of the modified example 2 of Embodiment 1. Figure 12C is a diagram comparing the torque characteristics shown in Figure 12A with those shown in Figure 12B. Figure 13 is a vertical cross-sectional view showing an example of the configuration of the compressor of Embodiment 2. Figure 14 is a piping diagram showing an example of the configuration of the refrigeration system of Embodiment 3.

[0024] Embodiments of this disclosure will be described below with reference to the drawings. The following embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or its uses. Furthermore, while the same reference numerals in the drawings represent the same components, dimensions such as length, width, thickness, and depth have been appropriately altered from the actual scale for clarity and simplification of the drawings and may not correspond to actual relative dimensions.

[0025] (Embodiment 1) <Basic configuration of the motor> As shown in Figures 1 and 2, the motor (20) has a stator (21) and a rotor (31). The motor (20) is a compressor motor (20). The motor (20) is configured as an inner rotor type. The stator (21) has a stator core (22) and a plurality of windings (23). The stator core (22) is arranged to face the rotor (31) in the radial direction. The rotor (31) is configured to be rotatable together with the drive shaft (40). The rotor (31) rotates in a predetermined direction around the axis of the drive shaft (40) (hereinafter referred to as the rotation axis (O)). The rotor (31) has a rotor core (32) and a plurality of magnets (33), with alternating polarities in the circumferential direction.

[0026] In this disclosure, the direction in which the axis of rotation (O) extends is described as the "axial direction," the direction perpendicular to the "axial direction" is described as the "radial direction," and the direction around the axis of rotation (O) is described as the "circumferential direction." Furthermore, a cross-section along the "axial direction" is described as a "longitudinal section," and a cross-section perpendicular to the "axial direction" is described as a "transverse section."

[0027] The stator core (22) is formed, for example, by stacking multiple electrical steel sheets in the axial direction. The stator core (22) has an annular back yoke (24) and multiple teeth (25). The multiple teeth (25) extend radially inward from the inner circumferential surface of the back yoke (24). Multiple windings (23) are wound around the multiple teeth (25).

[0028] The rotor core (32) is formed, for example, by stacking multiple electromagnetic steel sheets in the axial direction. Multiple magnets (33) are arranged inside the rotor core (32). Multiple magnets (33) are permanent magnets such as ferrite magnets. Multiple magnets (33) are arranged in the circumferential direction of the rotor core (32) and are provided so as to penetrate the rotor core (32) in the axial direction.

[0029] The configuration of the motor (20) shown in Figures 1 and 2 is illustrative, and the number of poles of the motor (20), the shape of the stator core (22), the number of teeth (25) and magnets (33), the winding method of the windings (23), etc., are not particularly limited. In addition, although not shown in the figures, the characteristics of the motor (20) may be improved by placing end plates at the upper and lower ends in the axial direction of the rotor core (32), providing bolts that penetrate the end plates and the rotor core (32) in the axial direction, and tightening the laminated steel plates constituting the rotor core (32) in the axial direction.

[0030] <Rotor Configuration> In the motor (20) of Embodiment 1, as shown in Figure 3, the rotor (31) comprises a first rotor section (31a) having a rotor core (32) and a magnet (33), and a second rotor section (31b) having a rotor core (32) but not a magnet (33). The first rotor section (31a) and the second rotor section (31b) are arranged adjacent to each other in the axial direction.

[0031] As shown in Figures 4A and 4B, a through hole (30) into which a drive shaft (40) is inserted axially is provided at the radial center of the first rotor section (31a) and the second rotor section (31b). Viewed from the axial direction, the shape of the rotor core (32) of the first rotor section (31a) and the shape of the rotor core (32) of the second rotor section (31b) are substantially the same. Specifically, in the first rotor section (31a) and the second rotor section (31b), the rotor core (32) has six sets of two holes (34) arranged radially and spaced equally in the circumferential direction. The holes (34) are formed to penetrate the first rotor section (31a) and the second rotor section (31b) in the axial direction. In the first rotor section (31a), magnets (33) are placed in the holes (34), while in the second rotor section (31b), magnets (33) are not placed in the holes (34).

[0032] In the first rotor section (31a) and the second rotor section (31b), two holes (34) are arranged radially for each magnetic pole, and the holes (34) corresponding to the six magnetic poles are arranged circumferentially at equal intervals so as to surround the through hole (30). Each hole (34) has an arc shape that is convex radially inward when viewed from the axial direction. The ends of the holes (34) are located near the outer circumference of the rotor core (32) when viewed from the axial direction. In the first rotor section (31a), magnets (33) are fitted into each of the holes (34) of one magnetic pole, arranged magnetically in series.

[0033] The first rotor section (31a) generates magnetic torque through the magnet (33). Furthermore, because the rotor core (32) has a shape that allows magnetic flux to pass through differently depending on its position in the circumferential direction, the first rotor section (31a) and the second rotor section (31b) generate reluctance torque.

[0034] In the example shown in Figures 4A and 4B, the rotor (31) has six poles, but the number of poles of the rotor (31) is not particularly limited. Also, in this example, two holes (34) are provided for each magnetic pole, but the number of holes (34) corresponding to each magnetic pole is not particularly limited.

[0035] In the motor (20) of Embodiment 1, as shown in Figures 4A and 4B, when the magnetic pole centerline (CL) is defined as a hypothetical straight line drawn between the circumferential position (first position (P1)) where the magnetic flux from the magnet (33) in the rotor (31) is maximum (third position (P3)), that is, the circumferential position (third position (P3)) where the magnetic flux from the magnet (33) in the first rotor portion (31a) is maximum, and the rotation axis (O), the rotor core (32), or hole (34), of the second rotor portion (31b) is asymmetrical with respect to the magnetic pole centerline (CL) when viewed from the axial direction. Furthermore, as shown in Figure 4B, the circumferential position where the magnetic resistance of the rotor (31) is maximum (second position (P2)), that is, the circumferential position where the magnetic resistance of the second rotor section (31b) is maximum (fourth position (P4)), is shifted by an angle θx backward in the rotational direction of the rotor (31) relative to the first position (P1) (third position (P3)). Note that in Figures 4A and 4B, the magnetic pole centerline (CL) of one magnetic pole is set as the reference 0° of rotation.

[0036] In this example, the rotor core (32) of the second rotor section (31b) is positioned offset to the reverse side in the rotational direction of the rotor (31) relative to the rotor core (32) of the first rotor section (31a), thereby making the rotor core (32) of the second rotor section (31b) asymmetric with respect to the magnetic pole centerline (CL) when viewed from the axial direction. However, instead of this, the rotor core (32) of the second rotor section (31b) may be made asymmetric with respect to the magnetic pole centerline (CL) by changing the shape of the rotor core (32) of the second rotor section (31b), i.e., the hole (34) itself. Alternatively, instead of making the rotor core (32) of the second rotor section (31b) asymmetric with respect to the magnetic pole centerline (CL), the magnet (33) may be positioned asymmetrically with respect to the magnetic pole centerline (CL) in the hole (34) of the rotor core (32) of the second rotor section (31b).

[0037] <Circumferential position where magnetic flux from the magnet is maximum> The "circumferential position (first position (P1)) where the magnetic flux from the magnet (33) on the rotor (31) is maximum" can be determined, for example, by rotating the rotor (31) with the terminals of the motor (20) open, measuring the angle of the rotor (31) and the induced voltage generated in the winding (23), and evaluating the measurement results.

[0038] Specifically, as shown in Figure 5A, the motor to be measured (measurement motor) is connected to another motor (load motor) that rotates the measurement motor at a constant rotational speed, and the U-phase and V-phase of the measurement motor and the rotational position sensor are connected to an oscilloscope. Next, while the measurement motor is rotated by the load motor, the line voltage Vuv between the U-phase and V-phase is acquired by the oscilloscope, and the rotational position information of the measurement motor measured by the rotational position sensor is acquired. Next, the acquired line voltage Vuv is Fourier transformed to obtain a fundamental waveform as shown in Figure 5B, and the rotational position information at the maximum value of the fundamental waveform of the line voltage Vuv is determined. Next, in order to convert the rotational position information of the line voltage Vuv to the rotational position information of the U-phase voltage, a phase of (30 / number of pole pairs)° is added to the rotational position information of the line voltage Vuv, and further, in order to convert the rotational position information of the U-phase voltage to the rotational position information of the U-phase magnetic flux, a phase of (90 / number of pole pairs)° is subtracted from the rotational position information of the U-phase voltage. By aligning the rotor position with the rotational position information of the U-phase magnetic flux obtained in this way, the "circumferential position where the magnetic flux from the magnet is maximum" can be identified, for example, as shown in Figure 5C. In the example shown in Figure 5C, the position where the U-phase coil (winding (23)) and the magnet (33) face each other is the "circumferential position where the magnetic flux from the magnet (33) on the rotor (31) is maximum (first position (P1))", that is, the "circumferential position where the magnetic flux from the magnet (33) on the first rotor section (31a) is maximum (third position (P3))". Note that in Figure 5C, the same reference numerals are used for the same components as in Figures 1 to 3 and Figure 4A.

[0039] <Circumferential position where magnetic resistance is maximum> The "circumferential position (second position (P2)) where the magnetic resistance of the rotor (31) is maximum" can be determined by measuring the inductance. With the rotor (31) locked at each angle of the rotor (31), an AC voltage is applied to the two terminals and the AC current is measured, and the inductance can be calculated from the AC voltage and AC current. The "circumferential position where the inductance is minimum" is the "circumferential position (second position (P2)) where the magnetic resistance of the rotor (31) is maximum".

[0040] Specifically, as shown in Figure 6A, the motor to be measured (measurement motor) is connected to another motor (load motor) used to change the fixed position of the measurement motor. The U-phase and V-phase of the measurement motor are connected to a power meter and a power supply, and a rotation position sensor is connected to an oscilloscope. Next, while fixing the measurement motor so that it does not rotate using the load motor, an AC voltage is applied to the U-phase and V-phase, and the RMS values ​​of the line voltage and phase current between the U-phase and V-phase are obtained using the power meter, while the rotation position information of the measurement motor measured by the rotation position sensor is obtained using the oscilloscope. The above measurements are repeated for half a cycle of the electrical angle while changing the rotation position of the measurement motor with the load motor. Next, using the RMS value of the line voltage Vuv and the RMS value of the U-phase current Iu between the U-phase and V-phase, the angular frequency of the power supply ωps, and the armature resistance Ra for one phase, the inductance Luv between the U-phase and V-phase is given by the following formula: Luv = √((Vuv / Iu) 2 - (2Ra) 2 Based on ) / ωps, the calculation is repeated for half a period of the electrical angle. Next, the obtained inductance Luv between the U-phase and V-phase is Fourier transformed to obtain the fundamental wave waveform as shown in Figure 6B, and the rotational position information where the inductance Luv between the U-phase and V-phase is minimized is determined. Next, in order to convert the rotational position information of the inductance Luv between the U-phase and V-phase into the rotational position information of the inductance of the U-phase, a phase of (30 / number of pole pairs)° is added to the rotational position information of the inductance Luv between the U-phase and V-phase. By aligning the rotor position with the rotational position information of the U-phase inductance obtained in this way, the "circumferential position where the magnetic resistance is maximum" is identified, for example, as shown in Figure 6C. In the example shown in Figure 6C, the position where the U-phase coil (winding (23)) and the hole (34) face each other is the "circumferential position where the magnetic resistance in the rotor (31) is maximum (second position (P2))", that is, the "circumferential position where the magnetic resistance in the second rotor part (31b) is maximum (fourth position (P4))". In Figure 6C, the same reference numerals are used for components that are the same as those in Figures 1 to 3 and Figure 4B.

[0041] <Torque Characteristics> As described above, in the motor (20) of Embodiment 1, as shown in Figures 4A and 4B, the circumferential position where the magnetic resistance of the rotor (31) is maximum (second position (P2)), that is, the circumferential position where the magnetic resistance of the second rotor section (31b) is maximum (fourth position (P4)), is shifted to the reverse side in the rotational direction of the rotor (31) compared to the circumferential position where the magnetic flux from the magnet (33) of the rotor (31) is maximum (first position (P1)), that is, the circumferential position where the magnetic flux from the magnet (33) of the first rotor section (31a) is maximum (third position (P3)). As a result, as shown in Figures 7A and 7B, the current phase at which the reluctance torque generated by the second rotor section (31b) reaches its peak value can be increased so that the current phase at which the reluctance torque generated by the second rotor section (31b) reaches its peak value is separated from the current phase at which the magnetic torque generated by the first rotor section (31a) reaches its peak value. As a result, as shown in Figure 7C, the output torque (total torque) of the rotor (31) can be improved in the region where the current phase is large.

[0042] More specifically, Figure 7A shows the torque characteristics of the motor (20) of Embodiment 1 when the fourth position (P4) is not shifted relative to the third position (P3) (comparative example), Figure 7B shows the torque characteristics of the motor (20) of Embodiment 1 when the fourth position (P4) is shifted relative to the third position (P3) by a shift angle θx toward the reverse side in the rotational direction of the rotor (31), and Figure 7C shows a comparison of the output torque of the comparative example and the output torque of Embodiment 1. In Figures 7A and 7B, the reluctance torque generated by the first rotor section (31a) is referred to as the "reluctance torque of the permanent magnet type rotor section," and the reluctance torque generated by the second rotor section (31b) is referred to as the "reluctance torque of the reluctance type rotor section."

[0043] Let the current phase at which the "reluctance torque of the reluctance type rotor part" shown in Fig. 7A reaches the peak value be θa, the current phase at which the "magnet torque (the magnet torque generated by the first rotor part (31a))" shown in Fig. 7A reaches the peak value be θb, and the current phase θa' at which the "reluctance torque of the reluctance type rotor part" shown in Fig. 7B reaches the peak value. The deviation angle θx is determined so as to satisfy 45° < θa' - θb and θa' = (θx × number of pole pairs) + θa. In other words, compared with the current phase θa at which the "reluctance torque of the reluctance type rotor part" shown in Fig. 7A reaches the peak value, the current phase θa' at which the "reluctance torque of the reluctance type rotor part" shown in Fig. 7B reaches the peak value is increased by "deviation angle θx × number of pole pairs", and thus the deviation angle θx is determined. As a result, the current phase at which the magnet torque generated by the first rotor part (31a) reaches the peak value and the current phase at which the reluctance torque generated by the second rotor part (31b) reaches the peak value are separated. As a result, the current phase at which the reluctance torque generated by the second rotor part (31b) reaches the peak value is increased, and as a result, the output torque (total torque) of the rotor (31) can be improved in the region where the current phase is large.

[0044] In the present disclosure, the "current phase" is the "phase of the alternating current supplied to the winding (23)" with the "phase of the alternating voltage induced in the winding (23) by the magnet (33)" as the reference (0°). In other words, the "phase difference" between the "phase of the alternating voltage induced in the winding (23) by the magnet (33)" and the "phase of the alternating current supplied to the winding (23)" is the "current phase". Therefore, the current phase θb at which the "magnet torque" shown in Figs. 7A and 7B reaches the peak value is 0°, the current phase θa at which the "reluctance torque (permanent magnet type rotor part and reluctance type rotor part)" shown in Fig. 7A reaches the peak value is 45°, and the current phase θa' at which the "reluctance torque (reluctance type rotor part)" shown in Fig. 7B reaches the peak value is greater than 45°.

[0045] In the motor (20) of Embodiment 1, as shown in FIG. 7B, at a current phase of 90° where the magnet torque becomes zero (the phase of the magnetic flux due to the alternating current supplied to the winding (23) is opposite to the direction of the magnetic flux due to the magnet (33)), the reluctance torque (reluctance-type rotor portion) generated by the alternating current supplied to the winding (23) and the rotor core (32) becomes a positive value. Therefore, as shown in FIG. 7C, the output torque (total torque) also becomes a positive value at a current phase of 90°. On the other hand, in the comparative example shown in FIG. 7A, the reluctance torque (permanent magnet-type rotor portion and reluctance-type rotor portion) becomes zero at a current phase of 90° like the magnet torque, so the output torque (total torque) also becomes zero at a current phase of 90°.

[0046] <Features of Embodiment 1> In the motor (20) of Embodiment 1, in the circumferential direction of the rotor (31), the second position (P2) where the magnetic resistance is maximum is shifted to the backward side in the rotation direction with respect to the first position (P1) where the magnetic flux due to the magnet (33) is maximum. For this reason, the difference between the current phase at which the magnet torque is maximum and the current phase at which the reluctance torque is maximum becomes large, and a decrease in the output torque can be suppressed over a wide range of current phases.

[0047] In the motor (20) of Embodiment 1, the difference between the phase of the alternating voltage induced in the winding (23) by the magnet (33) and the phase of the alternating current supplied to the winding (23) is defined as the phase difference. When the phase difference is such that the magnet torque generated by the magnet (33) and the alternating current becomes zero and the direction of the magnetic flux due to the alternating current is opposite to the direction of the magnetic flux due to the magnet (33), it may be configured such that the reluctance torque generated by the rotor core (32) and the alternating current becomes a positive value. By doing so, even in the region where the phase difference at which the magnet torque becomes zero, that is, the current phase is large, the reluctance torque becomes a positive value, so the output torque can be increased in the region where the current phase is large. Therefore, weak magnetic flux control can be performed so that the voltage does not increase in the region where the current phase is large.

[0048] Generally, in air conditioning systems, maximum torque control is performed in the low-speed range of the compressor motor. In maximum torque control, the current phase is adjusted so that the output torque is maximized. In this case, operation is performed in a small range where the current phase is 45° or less. However, with maximum torque control, operation in the high-speed range is not possible because the voltage saturates due to the magnetic flux of the magnet. In contrast, operation in the high-speed range becomes possible by performing flux weakening control. In flux weakening control, the magnetic flux of the magnet is weakened by bringing the current phase closer to 90°, thereby suppressing the voltage rise and enabling operation up to the high-speed range.

[0049] Furthermore, in the region where the current phase is small, the "reluctance torque of the reluctance-type rotor section" shown in Figure 7B becomes negative, resulting in a decrease in the output torque of the motor (20) of Embodiment 1 compared to the comparative example, as shown in Figures 7C and 8A. However, when the motor (20) of Embodiment 1 (a motor for a compressor) is used in an air conditioning system where operation is performed in the region where the current phase is small, the decrease in output torque is small because of the low torque and low current, as shown in Figure 8B. This is because the proportion of reluctance torque decreases as the current decreases, and the effect of the decrease in reluctance torque becomes smaller. Note that the torque characteristics shown in Figure 8A are those obtained with a large current of 30A, and the torque characteristics shown in Figure 8B are those obtained with a large current of 10A.

[0050] In the motor (20) of Embodiment 1, the rotor (31) may include a first rotor section (31a) equipped with a rotor core (32) and a magnet (33), and a second rotor section (31b) arranged axially adjacent to the first rotor section (31a), equipped with a rotor core (32) but not with a magnet (33). Here, when the circumferential position in the first rotor section (31a) where the magnetic flux due to the magnet (33) is maximum is defined as the third position (P3), and the circumferential position in the second rotor section (31b) where the magnetic resistance is maximum is defined as the fourth position (P4), the fourth position (P4) is shifted backward in the rotational direction of the rotor (31) relative to the third position (P3). As a result, the difference between the current phase in which the magnet torque generated by the first rotor section (31a) is maximum and the current phase in which the reluctance torque generated by the second rotor section (31b) is maximum becomes large, so that the decrease in output torque can be suppressed over a wide range of current phases. In this case, when viewed from the axial direction, the shape of the rotor core (32) of the first rotor section (31a) is substantially the same as the shape of the rotor core (32) of the second rotor section (31b), and the rotor core (32) of the second rotor section (31b) may be positioned offset to the rearward side in the rotational direction of the rotor (31) relative to the rotor core (32) of the first rotor section (31a). In this way, since the rotor core (32) of the first rotor section (31a) and the rotor core (32) of the second rotor section (31b) have the same shape, the manufacturing of the rotor (31) becomes easier.

[0051] On the other hand, as in the motor described in Patent Document 1, when the current phase at which the permanent magnet rotor generates maximum torque is matched with the current phase at which the reluctance rotor generates maximum torque, the output torque increases in the region where the matched current phase and the surrounding current phases are small, but decreases in the region where the current phases are large.

[0052] (Modification 1 of Embodiment 1) In Embodiment 1, as shown in Figures 3, 4A, and 4B, the rotor (31) is composed of a first rotor section (31a) having a rotor core (32) and a magnet (33), and a second rotor section (31b) having a rotor core (32) but not having a magnet (33).

[0053] In contrast, this modified example has a single-structure rotor (31) (see Figure 1) comprising a rotor core (32) and magnets (33), and in the rotor (31), as shown in Figure 9B, at least some of the multiple magnets (33) are configured asymmetrically with respect to the magnetic pole centerline (CL) when viewed from the axial direction. The motor (20) of this modified example does not have a reluctance-type rotor section like the second rotor section (31b) of Embodiment 1.

[0054] When the magnet (33) is configured symmetrically with respect to the magnetic pole centerline (CL), as shown in the comparative example in Figure 9A, there exists a "first circumferential position (P1) where the magnetic flux from the magnet (33) is maximum" and a "second circumferential position (P2) where the magnetic resistance is maximum" on the magnetic pole centerline (CL).

[0055] In contrast, in the rotor (31) of this modified example shown in Figure 9B, among the magnets (33) that constitute each magnetic pole, the magnets (33) arranged in the outer peripheral holes (34) are shifted to the forward side in the rotational direction of the rotor (31), so that the magnets (33) are configured asymmetrically with respect to the magnetic pole centerline (CL). The magnets (33) arranged in the inner peripheral holes (34) may be configured symmetrically with respect to the magnetic pole centerline (CL). In this way, by shifting the position of at least some of the magnets (33), the field direction of the magnetic flux of the magnets is shifted, so that the "second circumferential position (P2) where magnetic resistance is maximum" can be shifted to the backward side in the rotational direction of the rotor (31) with respect to the "first circumferential position (P1) where the magnetic flux from the magnets (33) is maximum".

[0056] In Figures 9A and 9B, the same reference numerals are used for the same components as in Embodiment 1 shown in Figures 3, 4A, and 4B. Also, in Figures 9A and 9B, the direction of the magnetic flux from the magnet (33) in the rotor (31) is defined as the dm axis, and the direction in which the magnetic resistance of the rotor (31) is maximized is defined as the dr axis. In the comparative example shown in Figure 9A, the dm axis and dr axis coincide with the magnetic pole centerline (CL) in the outer circumference of the rotor (31), while the dm axis and dr axis do not coincide with the magnetic pole centerline (CL) in the inner circumference of the rotor (31). In this modified example shown in Figure 9B, the dr axis does not coincide with the magnetic pole centerline (CL) even in the outer circumference of the rotor (31).

[0057] As described above, in the motor (20) of this modified example, as shown in Figure 9B, the circumferential position (second position (P2)) where the magnetic resistance of the rotor (31) is maximum is shifted to the reverse side in the rotational direction of the rotor (31) compared to the circumferential position (first position (P1)) where the magnetic flux from the magnet (33) on the rotor (31) is maximum. As a result, as shown in Figures 10A and 10B, the current phase at which the reluctance torque generated by the rotor (31) reaches its peak value can be increased so that the current phase at which the magnetic torque generated by the rotor (31) reaches its peak value is separated from the current phase at which the reluctance torque generated by the rotor (31) reaches its peak value. Consequently, as shown in Figure 10C, the output torque (total torque) of the rotor (31) can be improved in the region where the current phase is large.

[0058] More specifically, Figure 10A shows the torque characteristics of the motor (20) of this modified example when the second position (P2) is not shifted relative to the first position (P1) (comparative example), Figure 10B shows the torque characteristics of the motor (20) of this modified example when the second position (P2) is shifted relative to the first position (P1) by a shift angle θx toward the reverse side in the rotational direction of the rotor (31), and Figure 10C shows a comparison of the output torque of the comparative example and the output torque of Embodiment 1.

[0059] Let θa be the current phase at which the "reluctance torque" shown in Figure 10A reaches its peak value, let θb be the current phase at which the "magnet torque" shown in Figure 10A reaches its peak value, and let θa' be the current phase at which the "reluctance torque" reaches its peak value shown in Figure 10B. Then the misalignment angle θx is determined such that 45° < θa' - θb θa' = (θx × number of pole pairs) + θa. In other words, the misalignment angle θx is determined such that the current phase at which the "reluctance torque" reaches its peak value shown in Figure 10B is larger by "misalignment angle θx × number of pole pairs" compared to the current phase θa at which the "reluctance torque" reaches its peak value shown in Figure 10A. This increases the current phase at which the reluctance torque generated by the rotor (31) reaches its peak value, so that the current phase at which the magnet torque generated by the rotor (31) reaches its peak value is separated from the current phase at which the reluctance torque generated by the rotor (31) reaches its peak value. As a result, the output torque (total torque) of the rotor (31) can be improved in the region where the current phase is large.

[0060] Furthermore, the current phase θb ​​at which the "magnet torque" shown in Figures 10A and 10B reaches its peak value is 0°, the current phase θa at which the "reluctance torque" shown in Figure 10A reaches its peak value is 45°, and the current phase θa' at which the "reluctance torque" shown in Figure 10B reaches its peak value is greater than 45°.

[0061] In the motor (20) of this modified example, as shown in Figure 10B, at a current phase of 90° where the magnet torque is zero (a current phase in which the direction of the magnetic flux due to the alternating current supplied to the winding (23) is opposite to the direction of the magnetic flux due to the magnet (33)), the reluctance torque generated by the alternating current supplied to the winding (23) and the rotor core (32) becomes a positive value. Therefore, as shown in Figure 10C, the output torque (total torque) also becomes a positive value at a current phase of 90°. In contrast, in the comparative example shown in Figure 10A, the reluctance torque, like the magnet torque, becomes zero at a current phase of 90°, so the output torque (total torque) also becomes zero at a current phase of 90°.

[0062] As described above, in this modified example, even when the rotor (31) has a single structure, the decrease in output torque can be suppressed over a wide range of current phases, similar to the first embodiment.

[0063] (Modification 2 of Embodiment 1) In Embodiment 1, as shown in Figure 3, the rotor (31) is composed of one first rotor part (31a) having a rotor core (32) and a magnet (33), and one second rotor part (31b) having a rotor core (32) but not having a magnet (33).

[0064] In contrast, in this modified example, as shown in Figure 11, the rotor (31) is composed of two first rotor sections (31a) and one second rotor section (31b), with the two first rotor sections (31a) positioned to sandwich the one second rotor section (31b) in the axial direction. Here, each first rotor section (31a) has a region that does not face the stator (21) in the radial direction. In other words, each first rotor section (31a) has an overhang that protrudes beyond the stator (21) in the axial direction. The cross-sectional configuration of each first rotor section (31a) is the same as the cross-sectional configuration of the first rotor section (31a) in the embodiment 1 shown in Figure 4A, and the cross-sectional configuration of the second rotor section (31b) is the same as the cross-sectional configuration of the second rotor section (31b) in the embodiment 1 shown in Figure 4B.

[0065] Furthermore, since the rotor portion that does not face the stator radially only generates magnetic torque, in this modified rotor (31), the first rotor portion (31a), which is a permanent magnet type rotor portion, is positioned in the region that does not face the stator (21) at both ends in the axial direction.

[0066] As described above, in the motor (20) of this modified example, similar to Embodiment 1 shown in Figures 4A and 4B, the circumferential position where the magnetic resistance of the rotor (31) is maximum (second position (P2)), that is, the circumferential position where the magnetic resistance of the second rotor section (31b) is maximum (fourth position (P4)), is shifted to the reverse side in the rotational direction of the rotor (31) compared to the circumferential position where the magnetic flux from the magnet (33) of the rotor (31) is maximum (first position (P1)), that is, the circumferential position where the magnetic flux from the magnet (33) of the first rotor section (31a) is maximum (third position (P3)). As a result, as shown in Figures 12A and 12B, the current phase at which the reluctance torque generated by the second rotor section (31b) reaches its peak value can be increased so that the current phase at which the magnetic torque generated by the first rotor section (31a) reaches its peak value is separated from the current phase at which the reluctance torque generated by the second rotor section (31b) reaches its peak value. As a result, as shown in Figure 12C, the output torque (total torque) of the rotor (31) can be improved in the region where the current phase is large.

[0067] More specifically, Figure 12A shows the torque characteristics of the motor (20) of this modified example when the fourth position (P4) is not shifted relative to the third position (P3) (comparative example), Figure 12B shows the torque characteristics of the motor (20) of this modified example when the fourth position (P4) is shifted relative to the third position (P3) by a shift angle θx toward the reverse side in the rotational direction of the rotor (31), and Figure 12C shows a comparison of the output torque of the comparative example and the output torque of this modified example. In Figures 12A and 12B, the reluctance torque generated by the first rotor section (31a) is referred to as the "reluctance torque of the permanent magnet type rotor section," and the reluctance torque generated by the second rotor section (31b) is referred to as the "reluctance torque of the reluctance type rotor section."

[0068] Figures 12A and 12B also show the magnet torque characteristics when no overhang is provided on the first rotor section (31a). The output torque (total torque) characteristics shown in Figures 12A and 12B are those when an overhang is provided on the first rotor section (31a). The output torque characteristics shown in Figure 12C are those when no overhang is provided on the first rotor section (31a) for the comparative example, and those for both cases (with and without an overhang) for this modified example.

[0069] In this modified example, the first rotor portion (31a) has an overhang (a region that does not face the stator (21) radially), which increases the magnet torque generated by the first rotor portion (31a) compared to the case without an overhang, as shown in Figures 12A and 12B. As a result, the output torque (total torque) increases, as shown in Figure 12C.

[0070] In this modified example, when the first rotor portion (31a) is arranged on both sides in the axial direction, the axial lengths of the first rotor portion (31a) on both sides may be different, and one of the first rotor portion (31a) may not have an overhang. Alternatively, the entire axial length of the first rotor portion (31a) may not face the stator core (22). In other words, the axial end of the second rotor core portion (32b) may not face the stator core (22) in the radial direction. Alternatively, similar to Embodiment 1, one first rotor portion (31a) may be provided, and an overhang may be provided on the first rotor portion (31a).

[0071] (Embodiment 2) As shown in Figure 13, the compressor (10) of Embodiment 2 is a rotary compressor. The compressor (10) has a casing (11), the motor (20) of Embodiment 1, a drive shaft (40), and a compression mechanism (50). In the following description, "up", "down", "right", and "left" refer to directions when the compressor (10) is viewed from the front (see arrows in Figure 13). "Up" and "down" are also the axial directions of the drive shaft (40). "Right" and "left" are directions perpendicular to the axial direction and are also the radial directions of the motor (20) (or casing (11)).

[0072] The casing (11) is a completely sealed container. The inside of the casing (11) is filled with high-pressure refrigerant discharged from the compression mechanism (50). The casing (11) is made of a metallic material. The casing (11) has a body (12), a bottom (13), and a top (14). The body (12) is a cylindrical member that extends vertically. The axis of the cylinder of the body (12) is vertical. The bottom (13) closes the lower end of the body (12), and the top (14) closes the upper end of the body (12). The casing (11) houses the motor (20), the drive shaft (40), and the compression mechanism (50) from top to bottom.

[0073] The motor (20) has its rotational speed controlled by an inverter device. In other words, the compressor (10) is an inverter type with a variable rotational speed. The stator (21) of the motor (20) is fixed to the inner circumferential surface of the body (12). The rotor (31) of the motor (20) rotates about the rotation axis (O), as described in Embodiment 1 above. The drive shaft (40) extends downward from the motor (20). The drive shaft (40) is rotationally driven by the motor (20). The drive shaft (40) is rotatably supported by a bearing (41) located below the motor (20).

[0074] The compression mechanism (50) includes a cylinder (51) and a piston (52) provided inside the cylinder (51). A cylinder chamber (53) is formed between the inner circumferential surface of the cylinder (51) and the outer circumferential surface of the piston (52). In the cylinder chamber (53), the piston (52), driven by the drive shaft (40), compresses the fluid.

[0075] The compressor (10) has an intake pipe (15) and a discharge pipe (16). The intake pipe (15) penetrates the body (12) radially and communicates with the cylinder chamber (53). Low-pressure refrigerant is drawn into the cylinder chamber (53) through the intake pipe (15). The discharge pipe (16) penetrates the top (14) axially and communicates with the internal space of the casing (11). The refrigerant compressed by the compression mechanism (50) flows through the core cut (not shown) of the motor (20) and is then discharged from the discharge pipe (16).

[0076] The compressor (10) of Embodiment 2 is equipped with the motor (20) of Embodiment 1, which can suppress the decrease in output torque over a wide range of current phases, thus improving energy efficiency.

[0077] Note that the configuration of the compressor (10) shown in Figure 13 is illustrative, and the compressor (10) is not limited to a rotary compressor. The compressor (10) may be a swing type, scroll type, screw type, turbo type, or other type of compressor.

[0078] (Embodiment 3) As shown in Figure 14, the refrigeration device (1) of Embodiment 3 is an air conditioner. The air conditioner (1) may be for cooling only or for heating only. The air conditioner (1) has a refrigerant circuit (1a) filled with refrigerant. The refrigerant circuit (1a) has the compressor (10), radiator (2), expansion valve (3), and evaporator (4) of Embodiment 2. The refrigerant circuit (1a) performs a vapor compression type refrigeration cycle. The air conditioner (1) may be an air conditioner that switches between cooling and heating. In this case, the air conditioner (1) further has a switching mechanism (for example, a four-way switching valve) for switching the direction of refrigerant circulation.

[0079] In the refrigeration cycle, the refrigerant compressed by the compressor (10) releases heat into the air in the heat exchanger (2). The refrigerant that has released heat is depressurized by the expansion valve (3) and evaporates in the evaporator (4). The evaporated refrigerant is drawn back into the compressor (10) (see arrow in Figure 14).

[0080] In the heat sink (2), heat exchange occurs between the refrigerant flowing through the heat sink (2) and the air blown by the first blower (BL1) driven by the first motor (M1). In the evaporator (4), heat exchange occurs between the refrigerant flowing through the evaporator (4) and the air blown by the second blower (BL2) driven by the second motor (M2).

[0081] The air conditioner (refrigeration unit) (1) of Embodiment 3 has the compressor (10) of Embodiment 2, which is highly energy efficient, and therefore can reduce power consumption.

[0082] Note that the configuration of the refrigeration system (1) shown in Figure 14 is illustrative, and the refrigeration system (1) is not limited to an air conditioner. The refrigeration system (1) may be a water heater, chiller unit, or cooling device that cools the air inside the storage area. The cooling device cools the air inside a refrigerator, freezer, or container.

[0083] (Other Embodiments) In Embodiment 1 and its Modification 2, two radially aligned holes (34) are provided at each magnetic pole of the first rotor portion (31a) and the second rotor portion (31b), but one or three or more radially aligned holes (34) may be provided. Also, in Modification 1 of Embodiment 1, two radially aligned holes (34) are provided at each magnetic pole of the rotor (31), but one or three or more radially aligned holes (34) may be provided.

[0084] In the above embodiment 1 and its modified example 2, no magnets (33) were provided in the holes (34) of the second rotor portion (31b). However, if the volume per unit length in the axial direction of the magnets (33) included in the first rotor portion (31a) is greater than the volume per unit length in the axial direction of the magnets (33) included in the second rotor portion (31b), then magnets (33) may be provided in the holes (34) of the second rotor portion (31b).

[0085] In Embodiment 1 and its modifications 1 and 2, the hole (34) is formed in an arc shape that is convex radially inward when viewed from the axial direction, but the shape of the hole (34) is not particularly limited. The cross-sectional shape of the hole (34) may include a portion that extends in a straight line. The hole (34) may have a first portion that is linear and perpendicular to the radial direction when viewed from the axial direction, and a second portion that extends from both ends of the first portion to the vicinity of the outer circumferential surface of the rotor core (32). The hole (34) may have other shapes besides the shape that is convex radially inward when viewed from the axial direction, for example, an arc shape that is convex radially outward when viewed from the axial direction, a linear shape that is perpendicular to the radial direction when viewed from the axial direction, a linear shape that extends radially when viewed from the axial direction, or a substantially V shape that is radially open when viewed from the axial direction.

[0086] Although embodiments including modifications have been described above, it should be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments and modifications may be combined or substituted as appropriate. In addition, the designations "first," "second," "third," etc. in the specification and claims are used to distinguish the phrases to which these designations are attached, and do not limit the number or order of such phrases.

[0087] As described above, this disclosure is useful for compressor motors, compressors, and refrigeration systems.

[0088] 1 Refrigeration unit 10 Compressor 20 Compressor motor 21 Stator 22 Stator core 23 Winding 31 Rotor 31a First rotor section 31b Second rotor section 32 Rotor core 33 Magnet 34a First hole 35a Outer hole (third hole) 35b Inner hole (third hole) 36a First outer core region (first core region) 37a Second hole 38a Fourth hole 39a Second outer core region (second core region) O Rotation axis CL Magnetic pole centerline P1 First position P2 Second position P3 Third position P4 Fourth position

Claims

1. A compressor motor (20) comprising: a rotor (31) that rotates in one direction about a rotation axis (O), having a rotor core (32) and magnets (33) with alternating polarities in the circumferential direction; and a stator (21) arranged radially opposite to the rotor (31), having a stator core (22) and windings (23), wherein the circumferential position in the rotor (31) where the magnetic flux due to the magnets (33) is maximum is defined as the first position (P1), the circumferential position in the rotor (31) where the magnetic resistance is maximum is defined as the second position (P2), and a line drawn virtually through the first position (P1) and the rotation axis (O) is defined as the magnetic pole centerline (CL), A compressor motor wherein, when viewed from the axial direction, at least a portion of the magnet (33) or the rotor core (32) is configured asymmetrically with respect to the magnetic pole center line (CL), and the second position (P2) is shifted backward in the rotational direction of the rotor (31) relative to the first position (P1).

2. A compressor motor (20) according to claim 1, wherein the difference between the phase of the AC voltage induced in the winding (23) by the magnet (33) and the phase of the AC current supplied to the winding (23) is defined as the phase difference, and when the phase difference is such that the magnet torque generated by the magnet (33) and the AC current becomes zero and the direction of the magnetic flux due to the AC current is opposite to the direction of the magnetic flux due to the magnet (33), the reluctance torque generated by the rotor core (32) and the AC current becomes a positive value.

3. A compressor motor (20) according to claim 1 or 2, wherein the rotor (31) comprises: a first rotor portion (31a) having the rotor core (32) and the magnet (33); and a second rotor portion (31b) arranged axially adjacent to the first rotor portion (31a), having the rotor core (32) but not the magnet (33); the third position (P3) is defined as the circumferential position in the first rotor portion (31a) where the magnetic flux due to the magnet (33) is maximum, and the fourth position (P4) is defined as the circumferential position in the second rotor portion (31b) where the magnetic resistance is maximum, and the fourth position (P4) is shifted backward in the rotational direction of the rotor (31) relative to the third position (P3).

4. A compressor motor (20) according to claim 3, wherein, when viewed from the axial direction, the shape of the rotor core (32) of the first rotor portion (31a) is substantially the same as the shape of the rotor core (32) of the second rotor portion (31b), and the rotor core (32) of the second rotor portion (31b) is positioned offset to the reverse side in the rotational direction of the rotor (31) relative to the rotor core (32) of the first rotor portion (31a).

5. A compressor motor (20) according to claim 3 or 4, wherein the first rotor portion (31a) has a region that does not face the stator (21) in the radial direction.

6. A compressor motor (20) according to any one of claims 1 to 5, wherein at least a portion of the magnet (33) is configured asymmetrically with respect to the magnetic pole center line (CL).

7. A compressor comprising a compressor motor (20) according to any one of claims 1 to 6.

8. A refrigeration apparatus comprising the compressor (10) according to claim 7.

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