Motor, compressor and refrigeration equipment

Abstract

The invention discloses a motor, a compressor and refrigeration equipment, the motor comprises a stator punching sheet and a rotor punching sheet, the rotor punching sheet is rotatably arranged at the inner side of the stator punching sheet, the outer ring surface of the stator punching sheet is provided with n contact convex parts protruding outwards, the rotor punching sheet is provided with 2P magnet grooves, the magnet grooves are used for installing permanent magnets, and the n contact convex parts protrude outwards. The relationship between n and P is that n = P + / -2. According to the technical scheme, the inherent frequency of the stator can be improved, resonance caused by the fact that the inherent frequency of the motor and the compressor is close to the electromagnetic exciting force frequency is avoided, high-frequency carrier noise is reduced, and the performance of the motor and the compressor 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] As people's pursuit of environmental comfort continues to increase, higher and higher requirements are placed on the noise levels of motors and electrical appliances.

[0003] The motor vibration noise in the compressor is mainly electromagnetic noise. Electromagnetic noise is closely related to the electromagnetic excitation force, stator and compressor mode. Especially when the electromagnetic excitation force is close to the natural frequency of the motor and compressor, it will cause system resonance and cause large high-frequency carrier noise. Summary of the invention

[0004] The main purpose of the present invention is to provide a motor, aiming to reduce the high-frequency carrier noise of the motor.

[0005] To achieve the above-mentioned purpose, the motor proposed in the present invention includes a stator punching and a rotor punching. The rotor punching is rotatably arranged on the inner side of the stator punching. The outer ring surface of the stator punching is provided with n contact protrusions protruding outward. The rotor punching is provided with 2P magnet slots for installing permanent magnets. The relationship between n and P is: n=P±2.

[0006] Optionally, the stator punching sheet includes an annular stator yoke and a plurality of stator teeth arranged on the inner annular surface of the stator yoke, the plurality of stator teeth are distributed at intervals along the circumference of the annular stator yoke to form a stator slot between any two adjacent stator teeth, the number of the stator slots is Q, the width of the stator tooth is W, the arc length of the contact protrusion is L, and the value range of L is: 2P+4(Q / W)≤L≤2P+6(Q / W).

[0007] Optionally, the number of stator slots Q=15, and the number of magnet slots 2P=10.

[0008] Optionally, the contact convex portion is provided at a height h, and the range of h is: 0.5mm≤h≤1mm.

[0009] Optionally, the arc length of the contact protrusion gradually decreases in a direction away from the outer annular surface of the stator punching sheet.

[0010] Optionally, the contact protrusions are arranged at even intervals.

[0011] Optionally, the contact protrusion is integrally formed with the stator punching sheet.

[0012] Optionally, the magnet groove is configured as a V-shaped groove, a U-shaped groove, a W-shaped groove, a straight groove or an I-shaped groove.

[0013] Optionally, the material of the stator punching sheet and / or the rotor punching sheet is configured as a soft magnetic material.

[0014] Optionally, the thickness of the stator punching sheet and / or the rotor punching sheet is d, and the range of d is 0.2mm≤d≤0.35mm.

[0015] The present invention also provides a compressor, comprising the above-mentioned motor.

[0016] The present invention also provides a refrigeration device, comprising the above-mentioned compressor.

[0017] The above motor has at least the following beneficial effects:

[0018] The technical solution of the present invention adopts stator punching and rotor punching, and the rotor punching is rotatably arranged on the inner side of the stator punching, and the outer ring surface of the stator punching is provided with n contact convex parts protruding outward, and the rotor punching is provided with 2P magnet slots, and the magnet slots are used for permanent magnet installation, and the relationship between n and P is: n=P±2. Specifically, the contact convex part is used to contact with the stator casing, so that the overall stiffness of the stator casing and the stator core after shrink-fitting can be improved, and the matching area is moderate, which can make the motor have a higher efficiency, and at the same time, there is a reliable holding force between the stator and the stator casing in the compressor, so as to reduce the vibration of the compressor. Moreover, this solution limits the number of contact convex parts to P±2, which can improve the natural frequency of the stator, avoid the resonance caused by the natural frequency of the motor and the compressor being close to the frequency of the electromagnetic excitation force, thereby reducing the high-frequency carrier noise, and then improving the performance of the motor and the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] Figure 1 It is a structural schematic diagram of a stator housing, a stator punching sheet and a rotor punching sheet of an embodiment of the motor of the present invention;

[0021] Figure 2 It is a schematic structural diagram of the stator punching sheet and the rotor punching sheet of the motor of the present invention;

[0022] Figure 3 This is a comparison chart of the 60rps high-frequency carrier test of the motor of the present invention and the motor of the prior art;

[0023] Figure 4This is a comparison chart of the 90rps high-frequency carrier test of the motor of the present invention and the motor of the prior art.

[0024] Description of Figure Numbers:

[0025] Label name Label name 100 Stator punching 140 Stator slot 110 contact convex part 200 Rotor punching 120 Stator yoke 210 Magnet slot 130 Stator teeth 300 Stator housing

[0026] 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

[0027] 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.

[0028] 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.

[0029] 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.

[0030] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme 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 the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0031] The present invention provides a motor.

[0032] Reference Figures 1 to 4 In one embodiment of the present invention, the motor includes a stator punching 100 and a rotor punching 200. The rotor punching 200 is rotatably arranged on the inner side of the stator punching 100. The outer ring surface of the stator punching 100 is provided with n contact protrusions 110 protruding outward. The rotor punching 200 is provided with 2P magnet slots 210 for installing permanent magnets. The relationship between n and P is: n=P±2.

[0033] Specifically, the contact protrusion 110 is used to contact the stator housing 300, which can improve the overall stiffness of the stator housing 300 and the stator core after shrink-fitting, and the matching area is moderate, which can make the motor have a higher efficiency, and at the same time, there is a reliable holding force between the stator and the stator housing 300 in the compressor, thereby reducing the vibration of the compressor. In addition, this solution limits the number of contact protrusions 110 to P±2, which can increase the natural frequency of the stator and avoid resonance caused by the natural frequency of the motor and compressor being close to the frequency of the electromagnetic excitation force, thereby reducing high-frequency carrier noise and improving the performance of the motor and compressor.

[0034] Furthermore, in the present embodiment, the stator core and the stator casing 300 can be assembled by shrink fit, which is a method of utilizing the principle of thermal expansion and contraction to achieve interference fit. Specifically, the temperature of the stator core itself is maintained at room temperature, and then the stator casing 300 is heated to expand the stator casing 300, so that the diameter of the stator casing 300 becomes larger, and then the stator core is assembled into the stator casing 300, and then the stator casing 300 is cooled to restore the stator casing 300 to room temperature. During the cooling process, the diameter of the stator casing 300 is continuously reduced until the inner wall of the stator casing 300 abuts against the contact protrusion 110, and is continuously tightened so that the inner wall of the stator casing 300 abuts against the contact protrusion 110, thereby fixing the stator core inside the stator casing 300.

[0035] Optionally, the stator punching sheet 100 includes an annular stator yoke 120 and a plurality of stator teeth 130 disposed on the inner annular surface of the stator yoke 120. The plurality of stator teeth 130 are distributed at intervals along the circumference of the annular stator yoke 120 to form a stator slot 140 between any two adjacent stator teeth 130. The number of stator slots 140 is Q, the width of the stator teeth 130 is W, and the arc length of the contact protrusion 110 is L, and the value range of L is: 2P+4(Q / W)≤L≤2P+6(Q / W). The contact protrusion 110 corresponds to the order of the force generated by the stator and the rotor, which can improve the stator stiffness while improving the stator natural frequency and reducing high-frequency noise; and the arc segment length of the stator punching sheet 100 and the contact protrusion 110 can increase the compressor flow area when the stator laser welding is satisfied.

[0036] It should be noted that the unit of the width W of the stator tooth 130 is mm, and the unit of the arc length L of the contact protrusion 110 is mm.

[0037] Further, the conductor is axially wound around the stator teeth 130 to form a winding. The conductor can use enameled wire, such as acetal enameled wire, polyester enameled wire, polyurethane enameled wire, modified polyester enameled wire, polyesterimide enameled wire, etc. The enameled wire is a main type of winding wire, consisting of a conductor and an insulating layer. The bare wire is annealed and softened, and then painted and baked for multiple times. It has four major properties: mechanical properties, chemical properties, electrical properties, and thermal properties. Among them, the most widely used is the polyesterimide / polyamideimide composite layer enameled wire, which has high heat resistance, and also has the characteristics of freezing resistance, severe cold resistance, radiation resistance, etc. It has high mechanical strength, stable electrical properties, good chemical resistance and refrigerant resistance, and strong overload capacity. It is widely used in refrigerator compressors, air-conditioning compressors, power tools, explosion-proof motors, etc., as well as motors and electrical appliances used under high temperature, severe cold, radiation resistance, overload and other conditions.

[0038] Furthermore, each stator tooth 130 includes a first tooth shoe and a second tooth shoe, wherein the first tooth shoe and the second tooth shoe both extend along the circumferential direction of the annular stator yoke 120, the first tooth shoe is located on a first side of the center line of the stator tooth 130, and the second tooth shoe is located on a second side of the center line. The arrangement of the first tooth shoe and the second tooth shoe can prevent the magnetic force generated when the motor is working from causing the winding to gradually move toward the rotor core, thereby preventing the winding from being separated from the stator tooth 130, improving the working stability of the winding, and extending the service life of the motor.

[0039] Furthermore, the first tooth shoe of one stator tooth 130 of two adjacent stator teeth 130 is not in contact with the second tooth shoe of the other stator tooth 130, that is, the stator slot 140 formed between the two adjacent stator teeth 130 has a notch, and the notch is also opened facing the rotor opening; that is, the gap between the adjacent first tooth shoe and the second tooth shoe. If the notch of the stator slot 140 is too small, it may cause difficulties in winding the winding. At the same time, the four corners of the stator slot 140 are arranged in an arc shape. Such an arrangement can ensure the mechanical strength of the end where the stator tooth 130 and the stator yoke 120 are connected, and at the same time, it can also improve the slot area utilization rate of the stator slot 140.

[0040] Furthermore, the tooth top of the stator tooth 130 includes an inwardly curved arc portion, that is, the end of the stator tooth 130 away from the stator yoke 120 includes an inwardly curved arc portion, and “inwardly” in this embodiment refers to the direction toward the center of the stator punching sheet 100 .

[0041] Preferably, the radii of the arc portions of the plurality of stator teeth 130 are equal and are concentric with the center of the stator punching sheet 100. Thus, when the stator is injection molded, the outer diameter of the inner mold can be set to be consistent with the radius of the arc portion, so that the inner mold can be positioned at the arc portion for injection molding.

[0042] Furthermore, the bottom of the stator slot 140 is arranged in an arc shape, and the arc coincides with the inner circumference of the stator yoke 120. Such an arrangement is beneficial to the magnetic force distribution when the motor is running.

[0043] Furthermore, the first tooth shoe and the second tooth shoe are symmetrically arranged about the center line of the stator tooth 130, which can facilitate processing. The purpose of using the stator tooth 130 with a symmetrical structure is twofold, namely (1) meeting the requirements of bidirectional rotation of the motor; and (2) avoiding the introduction of excessive magnetic field harmonics. Of course, it is not limited to a symmetrical arrangement.

[0044] Optionally, the number Q of the stator slots 140 is 15, and the number 2P of the magnet slots 210 is 10. Limiting the number of the stator slots 140 to 15 and limiting the number of the magnet slots 210 to 10 can reduce the production cost of the motor and improve the cost performance of the motor.

[0045] Furthermore, the number of stator slots 140 Q=15 can further improve the noise reduction effect and enhance the performance of the compressor. On the one hand, it meets the use requirements of a multi-slot stator core. On the other hand, by improving the structure of the stator slots 140, it is helpful to reduce the additional air gap to enhance the motor performance.

[0046] Optionally, the contact protrusion 110 is provided at a height h, and the range of h is: 0.5mm≤h≤1mm; this can ensure that there is a reliable holding force between the stator and the stator housing 300, thereby reducing the vibration of the compressor. If h<0.5mm, the contact protrusion 110 will not be able to contact the stator housing 300, so that the stator and the stator housing 300 will vibrate and generate noise. If h>1mm, the contact protrusion 110 will be too close to the stator housing 300, so that the stator housing 300 will be deformed, and even the stator core will not be able to be installed in the stator housing 300.

[0047] Optionally, the arc length of the contact protrusion 110 gradually decreases in the direction away from the outer annular surface of the stator punching sheet 100, and this is set to facilitate transition. Of course, the present invention is not limited to this. In other embodiments, the arc length of the contact protrusion 110 may also remain unchanged in the direction away from the outer annular surface of the stator punching sheet 100.

[0048] Optionally, the contact protrusions 110 are evenly spaced; this allows the stator core to contact the stator housing 300 in all directions, thereby improving the overall stiffness of the stator housing 300 and the stator core after shrink-fitting, and improving the natural frequency of the stator.

[0049] Optionally, the contact protrusion 110 is integrally formed with the stator sheet 100; the integrally formed structure is easy to manufacture and has a high overall structural strength and is uniform. Of course, the present invention is not limited thereto, and in other embodiments, the contact protrusion 110 can also be welded with the stator sheet 100.

[0050] Furthermore, in the present embodiment, the stator sheet 100 is an integrated structure, and the integrated structure can increase the structural strength of the stator sheet 100. In another embodiment, the stator sheet 100 is a block structure. The block structure is to divide the stator sheet 100 into a plurality of small structures, which are processed separately and then assembled. In one embodiment, each small structure includes a stator tooth 130 and a part of the stator yoke 120, which can be processed separately on each stator tooth 130 and then assembled together. These two structures have their own advantages and can be selected according to actual needs.

[0051] Optionally, the magnet groove 210 is configured as a V-shaped groove, a U-shaped groove, a W-shaped groove, a straight groove or an I-shaped groove.

[0052] Furthermore, in the present embodiment, the magnet slot 210 is arranged in a straight line. This is because the straight line magnet slot 210 has a simple structure and low process cost, which is convenient for reducing the production cost of the device core.

[0053] Optionally, in the second embodiment, the magnet slot 210 is arranged in a V-shape; by arranging the V-shaped magnet slot 210 on the rotor punching 200 and optimizing the angle parameters of the V-shaped magnet slot 210, the amount of permanent magnets embedded in the rotor punching 200 proposed by the present invention is significantly improved compared with the prior art. The V-shaped magnet slot 210 can increase the amount of embedded permanent magnets, thereby increasing the torque density of the motor, and further effectively increasing the back electromotive force of the motor and the efficiency of the motor. Through this V-shaped magnet slot 210 structure, the amount of embedded permanent magnets is significantly increased, thereby increasing the torque density of the motor, which can meet the requirements of high efficiency and miniaturization of the motor.

[0054] Optionally, in other embodiments, the magnet slot 210 may also be provided in the form of a U-shaped slot, a W-shaped slot or an I-shaped slot, which may be selected according to actual needs during specific implementation.

[0055] It should be noted that magnet slots 210 of different shapes can be provided according to different requirements, that is, the shapes of the magnet slots 210 of the same rotor core can be the same or different.

[0056] Furthermore, the structure of the magnet slot 210 being symmetrical along the magnetic pole center line of the rotor core magnetic pole can be implemented as a preferred solution of the embodiment of the present invention.

[0057] Optionally, in one embodiment, the mass percentage of heavy rare earth elements in the permanent magnet is 0, that is, the permanent magnet does not contain heavy rare earth elements, which reduces the consumption of strategic resources, is conducive to the sustainable development of resources, and reduces the manufacturing cost of the motor, which is suitable for promotion and application. It is understandable that the mass percentage of heavy rare earth elements in the permanent magnet can also be other values, for example, the mass percentage of heavy rare earth elements in the permanent magnet is 0.005%, 0.01%, 0.025%, etc. Among them, the heavy rare earth elements can also include other elements that can become components of the permanent magnet.

[0058] Furthermore, in one embodiment, the material used for the permanent magnet may be a neodymium iron boron permanent magnet, which has excellent magnetic properties and can meet the use requirements of the motor. It is understandable that the permanent magnet may also be other permanent magnets that meet the requirements.

[0059] Optionally, the material configuration of the stator punching sheet 100 and / or the rotor punching sheet 200 is a soft magnetic material; soft magnetic material can achieve a larger magnetization intensity with a smaller external magnetic field. Soft magnetic material has low coercive force and high magnetic permeability, which is beneficial to reducing the loss of the rotor core and the stator core, that is, reducing the iron loss of the motor, which is beneficial to improving the performance of the motor.

[0060] Further, in one embodiment, the stator punching sheet 100 and / or the rotor punching sheet 200 are made of silicon steel sheets, the silicon content of silicon steel is 1.0-4.5%, and silicon alloy steel with a carbon content of less than 0.08% can be called silicon steel. Silicon steel has the characteristics of high magnetic permeability, low coercive force, and large resistivity, so the hysteresis loss and eddy current loss are small. The low iron loss of silicon steel can save a lot of electric energy and extend the working time of the motor and transformer. In addition, the high magnetic induction of silicon steel can reduce the excitation current and save electric energy. The high magnetic induction of silicon steel can increase the maximum magnetic induction when designing the stator core and the rotor core, and at the same time make the stator core and the rotor core smaller, reduce the weight of the stator core and the rotor core, save silicon steel, wires, insulation materials and structural materials, etc., which not only reduces the motor loss and manufacturing cost, but also facilitates assembly and transportation. Of course, the present invention is not limited to this. In some other embodiments, the stator punching sheet 100 and / or the rotor punching sheet 200 can also be made of neodymium iron boron or ferrite or other permanent magnetic materials.

[0061] Furthermore, in one embodiment, the stator teeth 130 are made of oriented electrical steel material, and the stator yoke 120 is made of non-oriented electrical steel material. Since the cost of non-oriented electrical steel material is lower and the iron loss of oriented electrical steel material is smaller, and the magnetic induction is better, this can avoid the need to replace all the stator punching sheets 100 with oriented electrical steel material when replacing them. Only the stator teeth 130 need to be replaced with oriented electrical steel material, which is beneficial to reducing costs. On the other hand, the excellent magnetic directivity of the oriented electrical steel material is utilized to improve the tooth magnetic permeability of the stator core and reduce the tooth iron loss, thereby improving the efficiency of the motor.

[0062] Furthermore, in one embodiment, the rotor punching sheet 200 and the stator punching sheet 100 can be made of different materials or shapes, so as to meet the requirements of different processing technologies of the stator and the rotor, and to select suitable punching sheets according to the performance requirements of the motor to form the rotor core and the stator core, thereby ensuring good performance of the electrode, and also improving the wide application range of the motor. Of course, the present invention is not limited to this. In some other embodiments, the stator punching sheets 100 stacked into the stator core and the rotor punching sheets 200 stacked into the rotor core are made of the same material, which is conducive to the mass production of punching sheets and reduces manufacturing costs.

[0063] Optionally, the thickness of the stator punching sheet 100 and / or the rotor punching sheet 200 is d, and the range of d is 0.2mm≤d≤0.35mm; in this way, on the one hand, it can ensure that the rotor and the stator cooperate with each other to generate sufficient induced current for user use; on the other hand, it can avoid the occurrence of large eddy current damage due to the excessive thickness of the stator punching sheet 100 and the rotor punching sheet 200, so as to extend the service life of the motor, and by limiting the plate thickness of the rotor punching sheet 200 and the stator punching sheet 100, on the premise of meeting their functional requirements, avoid unnecessary product materials, reduce production costs, reduce product weight, and enhance user experience.

[0064] The present invention also proposes a compressor, which includes a motor. The specific structure of the motor refers to the above-mentioned embodiment. Since the compressor adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0065] The present invention also proposes a refrigeration device, which includes a compressor. The specific structure of the compressor refers to the above embodiment. Since the refrigeration device adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here one by one.

[0066] 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: The motor includes a stator punching and a rotor punching. The rotor punching is rotatably arranged on the inner side of the stator punching. The outer ring surface of the stator punching is provided with n contact protrusions protruding outward. The rotor punching is provided with 2P magnet slots for installing permanent magnets. The relationship between n and P is: n=P±2.

2. The motor according to claim 1, characterized in that The stator punching sheet includes an annular stator yoke and a plurality of stator teeth arranged on the inner annular surface of the stator yoke. The plurality of stator teeth are distributed at intervals along the circumference of the annular stator yoke to form a stator slot between any two adjacent stator teeth. The number of the stator slots is Q, the width of the stator tooth is W, the arc length of the contact protrusion is L, and the value range of L is: 2P+4(Q / W)≤L≤2P+6(Q / W).

3. The motor according to claim 2, characterized in that The number of the stator slots Q=15, and the number of the magnet slots 2P=10.

4. The motor according to claim 1, characterized in that The contact convex portion is provided at a height h, and the range of h is: 0.5mm≤h≤1mm.

5. The motor according to claim 1, characterized in that The arc length of the contact protrusion gradually decreases in a direction away from the outer annular surface of the stator punching sheet.

6. The motor according to claim 1, characterized in that The contact protrusions are arranged at even intervals.

7. The motor according to claim 1, characterized in that The contact protrusion is integrally formed with the stator punching sheet.

8. The motor according to claim 1, characterized in that The magnet groove is configured as a V-shaped groove, a U-shaped groove, a W-shaped groove, a straight groove or an I-shaped groove.

9. The motor according to claim 1, characterized in that The material of the stator punching sheet and / or the rotor punching sheet is configured as a soft magnetic material.

10. The motor according to any one of claims 1 to 9, characterized in that The thickness of the stator punching sheet and / or the rotor punching sheet is d, and the range of d is 0.2mm≤d≤0.35mm.

11. A compressor, characterized in that: The invention comprises a motor as claimed in any one of claims 1 to 10.

12. A refrigeration device, characterized in that: Comprising the compressor of claim 11.

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