Motor, compressor and refrigeration equipment

Abstract

The invention discloses a motor, a compressor and refrigeration equipment, the motor comprises a stator and a rotor, the stator comprises a stator iron core and a winding, the stator iron core is provided with a stator groove, the winding is wound on the stator iron core and located in the stator groove, the rotor comprises a rotor iron core and a plurality of permanent magnets, and the permanent magnets are arranged on the rotor iron core. The rotor core is provided with a plurality of magnet grooves per pole, the permanent magnets are located in the magnet grooves per pole, the number of the stator grooves is 15, the number of the poles of the rotor is 10, the intrinsic coercive force of the permanent magnets is hcj, the included angle of the magnet grooves per pole is alpha, the thickness of the permanent magnets in the magnetization direction is h, hcj is smaller than or equal to 1800 kA / m, h is larger than or equal to 11 * alpha / hcj and smaller than or equal to 50 * alpha / hcj, and alpha / hcj is an anti-demagnetization factor. According to the technical scheme, by adjusting the thickness relation between the anti-demagnetization factor and the magnet, on the premise that it is guaranteed that demagnetization meets the requirement, use of heavy rare earth elements is reduced, the cost of the magnet is reduced, and meanwhile the cost performance of the motor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a motor, a compressor and a refrigeration device. Background Art

[0002] At present, the country has put forward higher requirements for the energy efficiency of compressors in the field of household air conditioners. The motor is the power element of the compressor, and the efficiency of the motor directly affects the energy efficiency of the compressor. At present, most compressor motors use variable frequency motors, and the magnets of variable frequency motors use permanent magnets. Permanent magnets contain many rare elements, such as dysprosium and terbium. Since heavy rare earth elements are national strategic resources, and with the development trend of new energy and variable frequency in the home appliance industry, the price of heavy rare earth elements has increased year by year.

[0003] In order to reduce the dependence on rare earths and reduce the cost of motors, permanent magnets with relatively less rare earth content can be used. The reduction of rare earth elements will reduce the intrinsic coercive force of permanent magnets, which directly affects the anti-demagnetization performance of motors. Therefore, it is necessary to design a motor structure that can carry less rare earth elements.

[0004] The number of stator slots of the variable frequency motors currently used in household air-conditioning compressors is 6, 9, or 12, and the number of rotor poles is 4, 6, or 8. The number of slots in the motor directly affects the demagnetization ability of the motor. When the number of slots in the motor increases, the demagnetization ability of the motor increases. Summary of the invention

[0005] The main purpose of the present invention is to provide a motor, which aims to reduce the use of heavy rare earth elements and the cost of magnets while improving the cost performance of the motor by adjusting the relationship between the anti-demagnetization factor and the thickness of the magnet, while ensuring that the demagnetization meets the requirements.

[0006] To achieve the above object, the motor provided by the present invention comprises:

[0007] A stator, the stator comprising a stator core and a winding, the stator core being provided with stator slots, the winding being wound on the stator core and located in the stator slots; and

[0008] A rotor, the rotor comprising a rotor core and a plurality of permanent magnets, the rotor core being provided with a plurality of magnet slots per pole, the permanent magnets being located in the magnet slots per pole;

[0009] The number of stator slots is, the number of rotor poles is, the intrinsic coercive force of the permanent magnet is hcj, the angle of each pole magnet slot is α, the thickness of the permanent magnet along the magnetization direction is h, hcj≤1800kA / m, 11*α / hcj≤h≤50*α / hcj, α / hcj is the anti-demagnetization factor.

[0010] Optionally, the magnet slots of each pole are arranged in a V-shape, with 90°≤α<180°.

[0011] Optionally, 100°≤α<130°.

[0012] Optionally, α=180°.

[0013] Optionally, the mass percentage of the heavy rare earth element in the permanent magnet is in the range of 0 to 1.5%; the mass percentage of dysprosium and / or terbium in the permanent magnet is in the range of 0 to 1.5%.

[0014] Optionally, the remanence Br of the permanent magnet ranges from 1.28T to 1.5T.

[0015] Optionally, the outer diameter of the stator is D, and 85mm≤D≤200mm.

[0016] Optionally, the inner diameter of the stator is D i , the outer diameter of the stator is D, 0.45≤D i / D≤0.65.

[0017] The present invention also provides a compressor, comprising the motor as described above.

[0018] The present invention also provides a refrigeration device, comprising the compressor as described above.

[0019] The motor of the technical solution of the present invention comprises a stator and a rotor, the stator comprises a stator core and a winding, the stator core is provided with a stator slot, the winding is wound on the stator core, and the winding is located in the stator slot, the rotor comprises a rotor core and a plurality of permanent magnets, the rotor core is provided with a plurality of magnet slots per pole, the permanent magnet is located in the magnet slot per pole, wherein the number of slots of the stator slot is 15, the number of poles of the rotor is 10, the intrinsic coercive force of the permanent magnet is defined as hcj (unit kA / m), the angle of the magnet slot per pole is α (unit °), the thickness of the permanent magnet along the magnetization direction is h (unit mm), and hcj≤1 800kA / m, and by further defining the relationship among hcj, α and h, 11*α / hcj≤h≤50*α / hcj, wherein α / hcj is the anti-demagnetization factor, the technical solution of the present invention provides a 15-slot 10-pole variable frequency motor for a compressor, the slot-pole structure of the motor has a stronger anti-demagnetization ability than the current existing household air-conditioning motor structure, and by adjusting the relationship between the anti-demagnetization factor and the thickness of the magnet, the use of heavy rare earth elements is reduced, the cost of the magnet is reduced, and the cost performance of the motor is improved while ensuring that the demagnetization meets the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of the structure when the magnet slots of each pole are arranged in a V-shape in one embodiment of the motor of the present invention;

[0022] Figure 2 It is a schematic structural diagram of a motor according to an embodiment of the present invention in which the magnet slots of each pole are arranged in a straight line.

[0023] Figure 3 for Figure 1 Added annotated diagrams with various parameters;

[0024] Figure 4 A comparison diagram of the evaluation samples and the reference values ​​of the motor of the present invention at different currents;

[0025] Figure 5 It is a comparison chart of the evaluation samples and the reference values ​​of the motor of the present invention at different speeds.

[0026] Description of Figure Numbers:

[0027] Label name Label name 11 Stator core 22 permanent magnet 111 Stator slot 23 Magnet slots per pole 12 Winding 24 Rivet holes 21 Rotor core

[0028] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0031] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, "and / or" in the full text includes three solutions. Taking A and / or B as an example, it includes technical solution A, technical solution B, and technical solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] Reference Figures 1 to 3 The present invention provides a motor, comprising:

[0034] A stator, the stator comprising a stator core 11 and a winding 12, the stator core 11 being provided with stator slots 111, the winding 12 being wound on the stator core 11 and being located in the stator slots 111; and

[0035] A rotor, the rotor comprising a rotor core 21 and a plurality of permanent magnets 22, the rotor core 21 being provided with a plurality of magnet slots 23 per pole, the permanent magnets 22 being located in the magnet slots 23 per pole;

[0036] The number of slots of the stator slot 111 is 15, the number of poles of the rotor is 10, the intrinsic coercive force of the permanent magnet 22 is hcj, the angle of each pole magnet slot 23 is α, the thickness of the permanent magnet 22 along the magnetization direction is h, hcj≤1800kA / m, 11*α / hcj≤h≤50*α / hcj, α / hcj is the anti-demagnetization factor.

[0037] The motor of the technical solution of the present invention comprises a stator and a rotor, the stator comprises a stator core 11 and a winding 12, the stator core 11 is provided with a stator slot 111, the winding 12 is wound on the stator core 11, and the winding 12 is located in the stator slot 111, the rotor comprises a rotor core 21 and a plurality of permanent magnets 22, the rotor core 21 is provided with a plurality of magnet slots 23 per pole, the permanent magnet 22 is located in the magnet slot 23 per pole, wherein the number of slots of the stator slot 111 is 15, the number of poles of the rotor is 10, the intrinsic coercive force of the permanent magnet 22 is defined as hcj (unit kA / m), the angle of the magnet slot per pole is α (unit °), and the permanent magnet 22 is magnetized along The thickness in the direction is h (unit: mm), hcj≤1800kA / m, and by further defining the relationship between hcj, α and h, 11*α / hcj≤h≤50*α / hcj, wherein α / hcj is the anti-demagnetization factor, the technical solution of the present invention provides a 15-slot 10-pole variable frequency motor for a compressor, the slot-pole structure of the motor has a stronger anti-demagnetization ability than the current existing household air-conditioning motor structure, and at the same time, by adjusting the relationship between the anti-demagnetization factor and the thickness of the magnet, on the premise of ensuring that the demagnetization meets the requirements, the use of heavy rare earth elements is reduced, the cost of the magnet is reduced, and the cost performance of the motor is improved.

[0038] The number of slots of the stator slots 111 of the variable frequency motor currently used in household air-conditioning compressors is 6, 9, and 12, and the number of rotor poles is 4, 6, and 8. The number of slots of the stator slots 111 of the motor directly affects the demagnetization ability of the motor, that is, when the number of stator slots of the motor increases, the demagnetization ability of the motor is enhanced, and then the anti-demagnetization ability of the motor is enhanced; while in the present application, the number of slots of the stator slots 111 is 15, and the number of rotor poles is 10, thereby further increasing the demagnetization ability and anti-demagnetization ability of the motor compared to the current household air conditioners.

[0039] It should be noted that the rotor with saturated magnetization is first placed at room temperature, and then the rotor magnetic flux φ0 is measured; then the rotor after the initial magnetic flux test is placed in a constant temperature box for more than 4 hours, and the temperature of the constant temperature box is set at the specified temperature of 130°C; then the test DC motor is connected to the DC power supply, and the demagnetization current is set according to the pre-set demagnetization current value (35A, 40A, 45A, etc.). After preparation, the rotor is taken out of the constant temperature box, and the demagnetization test tooling is installed. Under the DC demagnetization current, the rotor rotates one circle; after completion, the rotor is placed at room temperature for more than 4 hours, and then the temperature of the rotor and the magnetic flux φ1 after demagnetization are measured. Finally, the demagnetization rate is calculated, and the calculation formula is as follows: (the temperature of φi needs to be the same as φ0 when calculating): Demagnetization rate = (φi-φ0) / φ0×100%.

[0040] Furthermore, the demagnetization rate of the rotor is affected by current and temperature. Figure 4From the comparison between the motor of the present application and the reference value under different current conditions, it can be seen that, under different current conditions, the demagnetization rate of the motor of the present application is very close to the reference value, which shows that the motor of the present application can meet the needs of the compressor.

[0041] Further, refer to Figure 5 It can be seen that the motor efficiency in this application at different speeds is very close to the reference value, which shows that the motor in this application can meet the needs of the compressor.

[0042] Reference Figure 1 and Figure 3 In one embodiment, the magnet slot 23 of each pole is arranged in a V-shape, 90°≤α<180°; when α is less than 90° or α>180°, the permanent magnet 22 is not easy to be magnetized, and the utilization efficiency of the permanent magnet 22 is low. Therefore, when 90°≤α<180°, the utilization efficiency of the permanent magnet 22 can be improved.

[0043] Furthermore, 100°≤α<130°, and by further limiting the numerical range of α, the utilization efficiency of the permanent magnet 22 is further improved.

[0044] Reference Figure 2 In another embodiment, α=180°, that is, the magnet slot 23 of each pole is arranged in a straight line. At this time, the permanent magnet 22 is also convenient for magnetization, and the utilization efficiency of the permanent magnet 22 is higher, thereby improving the performance of the motor.

[0045] Of course, in other embodiments, the structure of the magnet slot 23 of each pole can also be set to a variety of different styles such as U-shaped slot, W-shaped slot or I-shaped slot. By setting the magnet slot 23 of each pole to a variety of different styles such as V-shaped slot, U-shaped slot, W-shaped slot, straight slot or I-shaped slot, it is possible to install permanent magnets 22 of different structures therein, making the motor manufacturing process more flexible and with more choices, which can meet a variety of different application scenarios and expand the applicability of the product.

[0046] In one embodiment, the mass percentage of the heavy rare earth element in the permanent magnet 22 is in the range of 0 to 1.5%; or the mass percentage of dysprosium and / or terbium in the permanent magnet 22 is in the range of 0 to 1.5%. Since dysprosium and terbium are heavy rare earth elements, heavy rare earth elements are national strategic resources, and the mass percentage of the heavy rare earth element in the permanent magnet 22 is positively correlated with the magnitude of the intrinsic coercive force hcj of the permanent magnet 22. Therefore, on the one hand, by limiting the mass percentage of dysprosium and / or terbium in the permanent magnet 22 to 0 to 1.5%, it is beneficial to reduce the use of dysprosium and / or terbium while ensuring the good anti-demagnetization ability of the motor, thereby reducing the manufacturing cost of the motor and improving the cost performance of the motor; on the other hand, by limiting the mass percentage of the heavy rare earth element in the permanent magnet 22 to 0 to 1.5%, it is beneficial to reduce the use of heavy rare earth elements while ensuring the good anti-demagnetization ability of the motor, thereby reducing the manufacturing cost of the motor and improving the cost performance of the motor.

[0047] In another embodiment, the mass percentage of dysprosium and / or terbium in the permanent magnet 22 is 0. On the one hand, the mass percentage of dysprosium in the permanent magnet 22 is 0, that is, the permanent magnet 22 does not contain heavy rare earth element dysprosium, which reduces the consumption of heavy rare earth element dysprosium by the permanent magnet 22, which is beneficial to energy saving; on the other hand, the mass percentage of terbium in the permanent magnet 22 is 0, that is, the permanent magnet 22 does not contain heavy rare earth element terbium, which reduces the consumption of heavy rare earth element terbium by the permanent magnet 22, which is beneficial to energy saving; on the other hand, the sum of the mass percentages of dysprosium and terbium in the permanent magnet 22 is 0, that is, the permanent magnet 22 does not contain heavy rare earth elements dysprosium and terbium, which reduces the consumption of heavy rare earth elements dysprosium and terbium by the permanent magnet 22, which is beneficial to the sustainable development of resources, energy saving, and reducing the manufacturing cost of the motor, and is suitable for popularization and application.

[0048] It is understandable that the mass percentage of dysprosium and / or terbium in the permanent magnet 22 may also be other values, for example, the mass percentage of dysprosium and / or terbium in the permanent magnet 22 is 0.005%, 0.01%, 0.025%, etc. Further, the permanent magnet 22 is a neodymium iron boron permanent magnet, which has excellent magnetic properties and can meet the use requirements of the motor.

[0049] Specifically, the remanence Br of the permanent magnet 22 is in the range of 1.28T to 1.5T. Among them, remanence refers to the surface field retained after the permanent magnet 22 is magnetized to technical saturation and the external magnetic field is removed, and Br is the residual magnetic induction intensity. By reasonably setting the remanence, under the same magnetic load, the larger the remanence Br value, the less the amount of rare earth elements in the permanent magnet 22, thereby reducing the manufacturing cost of the motor. At the same time, by reasonably setting the remanence, it is beneficial to reduce iron loss and thus improve the efficiency of the motor. Specifically, the remanence of the permanent magnet 22 is 1.28T, or 1.32T, or 1.5T, wherein T is the unit Tesla.

[0050] In this embodiment, the outer diameter of the stator is D, and 85 mm ≤ D ≤ 200 mm. By limiting the range of the outer diameter of the stator, the anti-demagnetization ability of the motor can be increased, thereby further reducing the use of rare earth elements, thereby reducing the production cost of the motor, and thereby improving the cost performance of the motor. At the same time, the stator outer diameter in the range of 85 to 200 can meet the requirements of the motor used in the compressor.

[0051] Furthermore, the inner diameter of the stator is Di, the outer diameter of the stator is D, and 0.45≤Di / D≤0.65; by further limiting the inner diameter and outer diameter of the stator within the range of 0.45 to 0.65, the moment of inertia can be increased, which is beneficial to the stable performance of the low-frequency energy efficiency of the compressor using the motor; at the same time, the motor has the best demagnetization ability, thereby obtaining higher system energy efficiency; at the same time, the use of rare earth elements is further reduced, thereby reducing the production cost of the motor, thereby improving the cost performance of the motor.

[0052] Specifically, the stator core 11 is formed by stacking a plurality of stator punchings, and the rotor core 21 is formed by stacking rotor punchings. In one embodiment, the rotor core 21 and the stator core 11 can be made of different materials or shapes, so as to meet the requirements of different processing technologies of the stator and the rotor, which is conducive to selecting suitable punchings to form the rotor core 21 and the stator core 11 according to the performance requirements of the motor, thereby ensuring good performance of the electrode, and also improving the wide application range of the motor. In another embodiment, the stator punchings stacked into the stator core 11 and the rotor punchings stacked into the rotor core 21 are the same, which is conducive to the mass production of punchings and reduces manufacturing costs.

[0053] Furthermore, the punching sheet is a soft magnetic material punching sheet, and the soft magnetic material can achieve a larger magnetization intensity with a smaller external magnetic field. The soft magnetic material has a low coercive force and a high magnetic permeability, which is beneficial to reducing the loss of the stator core 11 and / or the rotor core 21, that is, reducing the iron loss of the motor, and thus helping to improve the performance of the motor. Specifically, the punching sheet is a silicon steel sheet, and it is understandable that the punching sheet can also be made of other materials.

[0054] There are many factors that affect eddy current loss, including the cross-sectional area, thickness, frequency of induced electromotive force and magnetic flux density of the magnetic material. By arranging the rotor core 21 and the stator core 11 to be respectively composed of multiple layers of mutually insulated rotor punchings and stator punchings, the eddy current can be suppressed in each layer of rotor punchings or stator punchings, thereby reducing the eddy current loss generated thereby. That is, by avoiding interlayer eddy current conduction, the overall eddy current loss of the rotor core 21 and the stator core 11 can be significantly reduced. Specifically, the stator core 11 and the rotor core 21 are usually configured as silicon steel sheets, which can be the insulating surface layer formed by the paint film provided by them, or the insulating surface layer can be formed by applying insulating paint on the punching sheets without paint film by the motor manufacturer, or the punching sheets can be oxidized at the motor manufacturer to form the insulating surface layer.

[0055] In the related art, in order to ensure that the rotor core 21 does not have the problem of loose pieces or interlayer misalignment, or to ensure that the rotor core 21 does not deform due to the interlayer offset of the rotor core 21 during the winding process of the coil winding 12, the motor core is required to have sufficient stacking riveting strength. In order to ensure that the motor core has sufficient stacking riveting strength, in this embodiment, a plurality of rivet holes 24 are provided on the rotor core 21. The cooperation between the rivets and the rivet holes 24 can meet the fixing strength between the silicon steel sheets, thereby avoiding the problem of interlayer misalignment of the silicon steel sheets in the subsequent processing process.

[0056] It should be noted that in order to reduce or even avoid the problem of inter-layer eddy current conduction caused by this stacked riveting structure, glue bonding can be used between the rotor punchings instead of the stacked riveting method, so that the insulating surface layer of the silicon steel sheet at the rivet hole 24 will not be damaged, thereby avoiding the problem of eddy current inter-layer conduction. However, due to the high price of glue and low production efficiency of the production line, it has not been used in the motor of the air-conditioning compressor.

[0057] In the present embodiment, an axial hole and a flow hole are further provided on the rotor core 21. The axial hole is used to install the transmission shaft, thereby driving the transmission object to rotate. After the motor is used for a long time, its temperature is likely to rise, which may easily lead to demagnetization of the permanent magnet 22, thereby causing the permanent magnet 22 to lose its magnetism or reduce its magnetism. Therefore, in the present embodiment, a flow hole is provided on the rotor core 21, and a refrigerant flows in the flow hole. The refrigerant can reduce the temperature of the rotor core 21, thereby maintaining the permanent magnet 22 within an optimal range, thereby improving the performance of the motor.

[0058] The present invention also proposes a compressor, which includes a motor. The specific structure of the motor refers to the above-mentioned embodiments. Since the compressor of the present application adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0059] The present invention also proposes a refrigeration device, which includes the above-mentioned compressor, wherein the refrigeration device can be but is not limited to a refrigerator, a freezer, an air conditioner and other equipment with a refrigeration function. The specific structure of the compressor refers to the above-mentioned embodiment. Since the refrigeration device of the present application adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0060] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A motor, characterized in that: include: A stator, the stator comprising a stator core and a winding, the stator core being provided with stator slots, the winding being wound on the stator core and located in the stator slots; and A rotor, the rotor comprising a rotor core and a plurality of permanent magnets, the rotor core being provided with a plurality of magnet slots per pole, the permanent magnets being located in the magnet slots per pole; The number of stator slots is 15, the number of rotor poles is 10, the intrinsic coercive force of the permanent magnet is hcj, the angle of each pole magnet slot is α, the thickness of the permanent magnet along the magnetization direction is h, hcj≤1800kA / m, 11*α / hcj≤h≤50*α / hcj, α / hcj is the anti-demagnetization factor.

2. The motor according to claim 1, characterized in that The magnet slots of each pole are arranged in a V shape, 90°≤α<180°.

3. The motor according to claim 2, characterized in that 100°≤α<130°。 4. The motor according to claim 1, characterized in that α＝180°。 5. The motor according to claim 1, characterized in that The mass percentage of dysprosium and / or terbium in the permanent magnet is in the range of 0 to 1.5%; the mass percentage of heavy rare earth elements in the permanent magnet is in the range of 0 to 1.5%.

6. The motor according to claim 1, characterized in that The remanence Br of the permanent magnet ranges from 1.28T to 1.5T.

7. The motor according to claim 1, characterized in that The outer diameter of the stator is D, 85mm≤D≤200mm.

8. The motor according to claim 1, characterized in that The inner diameter of the stator is Di, the outer diameter of the stator is D, and 0.45≤Di / D≤0.

65.

9. A compressor, characterized in that: Comprising a motor as claimed in any one of claims 1 to 8.

10. A refrigeration device, characterized in that: Comprising a compressor as claimed in claim 9.

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