Rotor assembly, motor and compressor

Abstract

The invention provides a rotor assembly, a motor and a compressor. The rotor assembly comprises a rotating shaft sleeved with a rotor iron core; the rotor iron core is provided with a first rotor iron core and a second rotor iron core along the axial direction of the rotating shaft, and the axial length of the first rotor iron core is greater than the axial length of the second rotor iron core; the first rotor iron core is provided with magnetic steel grooves, and the magnetic steel grooves are internally provided with magnetic steel. The second rotor iron core is provided with a tooth groove, a conducting bar is arranged in the tooth groove, and two ends of the conducting bar are provided with end rings. The squirrel cage rotor and the permanent magnet rotor are arranged on the rotating shaft in a segmented mode, normal operation of the permanent magnet synchronous motor can be achieved under the condition that a frequency converter is not used, and therefore the manufacturing cost of the motor is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of compressors, and in particular relates to a rotor assembly, a motor and a compressor. Background Art

[0002] Permanent magnet synchronous motor (PMSM) has many advantages that make it the first choice in many applications, especially in situations where high efficiency and reliability are required. Permanent magnet synchronous motor has high power efficiency and high power factor, which helps to improve the overall energy efficiency of the system. Secondly, due to the magnetic field generated by the permanent magnet, the excitation loss caused by the magnetic field generated by the excitation current, that is, copper loss, is avoided. The rotor runs without current, which significantly reduces the temperature rise of the motor. Under the same load, the temperature rise is more than 20K lower. Thirdly, the permanent magnet synchronous motor has a simple structure and less maintenance, which reduces the processing and assembly costs and improves the reliability of the motor operation. In summary, permanent magnet synchronous motors are widely used in industrial and agricultural fields due to their high efficiency, high reliability, small size, light weight and energy saving. However, if a permanent magnet synchronous motor is selected, it is necessary to set up an additional matching inverter when the motor starts to change the current frequency to obtain the driving torque to realize the rotation of the rotor; this results in a waste of the cost of the whole machine under the condition of a single speed, so a self-starting high-efficiency motor is needed. Summary of the invention

[0003] Therefore, the present application provides a rotor assembly, a motor and a compressor, which can solve the problem in the prior art that the permanent magnet synchronous motor needs to be equipped with a frequency converter, resulting in high cost of the whole machine.

[0004] In order to solve the above problems, the present application provides a rotor assembly, comprising:

[0005] A rotating shaft, sleeved with a rotor core;

[0006] The rotor core is provided with a first rotor core and a second rotor core along the axial direction of the rotating shaft, and the axial length of the first rotor core is greater than the axial length of the second rotor core; the first rotor core is provided with a magnetic steel slot, and the magnetic steel is arranged in the magnetic steel slot; the second rotor core is provided with a tooth slot, and a guide bar is arranged in the tooth slot, and end rings are arranged at both ends of the guide bar.

[0007] In some embodiments,

[0008] Two first rotor cores are provided, which are respectively located at two axial ends of the second rotor core.

[0009] In some embodiments,

[0010] The rotor assembly further includes a baffle. Two baffles are provided and are disposed on one end of the first rotor core away from the second rotor core.

[0011] In some embodiments,

[0012] The baffle plate is provided with a mounting hole for mounting a dynamic balancing screw, and a plurality of the mounting holes are provided and are evenly arranged along the circumference of the baffle plate.

[0013] In some embodiments,

[0014] The rotating shaft comprises an assembly section for sleeved the rotor core, one end of the assembly section is provided with a flange, and the other end is provided with a threaded external thread and a locking nut; the rotor core is sleeved between the flange and the locking nut.

[0015] In some embodiments,

[0016] The outer circumferential surface of the assembly section and the inner circumferential surface of the rotor core are both provided with key grooves for key connection.

[0017] According to another aspect of the present application, a motor is provided, comprising the rotor assembly as described above.

[0018] In some embodiments,

[0019] The motor further includes a stator assembly, the stator assembly includes a stator core, the rotor core is inserted into the stator core, and along the axial direction of the stator core, the length of the rotor core is greater than the length of the stator core.

[0020] According to another aspect of the present application, a compressor is provided, comprising the rotor assembly as described above or the motor as described above.

[0021] A rotor assembly provided in the present application includes: a rotating shaft, on which a rotor core is sleeved; the rotor core is provided with a first rotor core and a second rotor core along the axial direction of the rotating shaft, and the axial length of the first rotor core is greater than the axial length of the second rotor core; the first rotor core is provided with a magnetic steel slot, and a magnetic steel is provided in the magnetic steel slot; the second rotor core is provided with a tooth slot, and a guide bar is provided in the tooth slot, and end rings are provided at both ends of the guide bar.

[0022] This application has the following beneficial effects:

[0023] By arranging the squirrel cage rotor and the permanent magnet rotor in sections on the rotating shaft, the normal operation of the permanent magnet synchronous motor can be achieved without using a frequency converter, thus reducing the manufacturing cost of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the implementation methods or the prior art descriptions. The drawings described below are merely exemplary, and for those of ordinary skill in the art, other implementation drawings can be derived from the provided drawings without creative work.

[0025] Figure 1 This is a schematic structural diagram of a rotor assembly according to an embodiment of the present application;

[0026] Figure 2 An axonometric view of a rotor assembly according to an embodiment of the present application;

[0027] Figure 3 This is a schematic diagram of the structure of the rotating shaft of an embodiment of the present application;

[0028] Figure 4 This is a schematic diagram of the structure of the baffle in an embodiment of the present application;

[0029] Figure 5 This is a schematic diagram of the structure of the permanent magnet rotor in an embodiment of the present application;

[0030] Figure 6 is a cross-sectional view of a permanent magnet rotor according to an embodiment of the present application;

[0031] Figure 7 This is a schematic diagram of the structure of a squirrel cage rotor according to an embodiment of the present application;

[0032] Figure 8 is a cross-sectional view of a squirrel cage rotor according to an embodiment of the present application;

[0033] Fig. 9 It is a cross-sectional view of the motor according to an embodiment of the present application.

[0034] The reference numerals are:

[0035] 1. rotating shaft; 11. flange; 12. external thread; 13. first keyway;

[0036] 2. baffle; 21. mounting hole;

[0037] 3. Permanent magnet rotor; 31. Magnetic steel slot; 32. Second key slot; 33. Magnetic steel;

[0038] 4. squirrel cage rotor; 41. second rotor core; 42. end ring; 43. third keyway;

[0039] 5. Lock nut;

[0040] 6. stator assembly; 61. stator core; 62. end winding. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0043] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0044] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0045] See also Figures 1 to 9 As shown, according to an embodiment of the present application, a rotor assembly includes:

[0046] The rotating shaft 1 is sleeved with a rotor core;

[0047] The rotor core is provided with a first rotor core and a second rotor core 41 along the axial direction of the rotating shaft 1, and the axial length of the first rotor core is greater than the axial length of the second rotor core 41; the first rotor core is provided with a magnetic steel slot 31, and a magnetic steel 33 is provided in the magnetic steel slot 31; the second rotor core 41 is provided with a tooth slot, and a guide bar is provided in the tooth slot, and end rings 42 are provided at both ends of the guide bar.

[0048] The squirrel cage asynchronous rotor motor has high reliability, simple mechanical structure, and no inverter is required during operation. Reasonable design of motor parameters can obtain larger starting torque and higher efficiency. However, compared with permanent magnet motors, the power factor and efficiency of squirrel cage asynchronous motors are smaller than those of permanent magnet synchronous motors of the same power. However, the squirrel cage asynchronous rotor motor drive does not require an inverter to start, and in some screw compressors and air compressors, the motor speed is constant. If an asynchronous motor is selected, the overall efficiency of the compressor is low.

[0049] The present application arranges the squirrel cage rotor 4 and the permanent magnet rotor 3 in sections on the rotating shaft 1, thereby achieving normal operation of the permanent magnet synchronous motor without using a frequency converter, thereby reducing the manufacturing cost of the motor.

[0050] The first rotor core is provided with a magnetic steel slot 31 , in which a magnetic steel 33 is arranged, forming a permanent magnet rotor 3 ; and the second rotor core 41 is provided with a tooth slot, in which a guide bar is passed, and end rings 42 are arranged at both ends of the guide bar, forming a squirrel cage rotor 4 .

[0051] The squirrel cage bars and magnetic steel 33 of the conventional asynchronous starting permanent magnet motor rotor are in the same rotor core. For example, in the same rotor core, the outer layer is a squirrel cage cast aluminum winding and the inner layer is a permanent magnet, or the outer layer of the rotor is a permanent magnet and the inner layer is a squirrel cage cast aluminum winding. This will limit the shape and size of the magnetic steel 33 and the shape of the cast aluminum slot, which is not conducive to the optimization of the slot. In this way, the design space of the rotor core is limited, and the squirrel cage rotor 4 and the permanent magnet rotor 3 are prone to interference, resulting in the following disadvantages:

[0052] ① Complex process: The design and manufacturing process of radial dual-rotor motors is relatively complex and the cost is relatively high, which may affect the overall price of the product.

[0053] ② Complex maintenance: Due to its complex structure, the maintenance and repair of radial twin-rotor motors are difficult and require professional technicians to operate.

[0054] ③ Large starting current: The radial twin-rotor motor requires a large current when starting, which may have a certain impact on the power grid.

[0055] The present application arranges a permanent magnet rotor 3 and a squirrel cage rotor 4 axially on the same rotating shaft 1. This axial segmented arrangement of the rotor can solve this problem. The squirrel cage rotor 4 and the permanent magnet rotor 3 do not occupy each other's space and are not restricted. The tooth slots and the magnetic steel slots 31 on the rotor core can be more freely optimized and designed, respectively, to improve the starting ability and load capacity of the motor. In the event of damage, they can be disassembled and repaired separately, which makes maintenance simpler. The starting current is easy to adjust and is only determined by the starting current of the asynchronous squirrel cage rotor.

[0056] The axial length of the first rotor core is greater than that of the second rotor core 41 , so that the rotor core in the magnetic field generated by the stator winding is mainly the permanent magnet rotor 3 , which can ensure the synchronous operation efficiency of the motor.

[0057] The combined rotor assembly of the present application, when the motor is operating normally, after three-phase AC is supplied to the stator winding of the motor, the squirrel cage rotor 4 starts to operate to provide the motor with starting torque to drive the shaft 1 to operate, and as the motor speed gradually rises to a certain speed, the permanent magnetic field in the permanent magnet rotor 3 interacts with the rotating magnetic field generated by the stator, and gradually reaches the synchronous speed of the motor and operates normally. Therefore, the motor does not need to use a frequency converter, but only needs to be normally connected to three-phase AC, and compared with the traditional three-phase asynchronous motor, it is more efficient and has a higher power factor, achieving low cost and high energy efficiency.

[0058] In some embodiments,

[0059] Two first rotor cores are provided, which are respectively located at two axial ends of the second rotor core 41 .

[0060] The entire rotor core is divided into three rotor sections, which are connected together by a rotating shaft 1. There is no need to set a separate partition between the squirrel cage rotor 4 and the permanent magnet rotor 3, but the end ring 42 of the squirrel cage rotor 4 is used for blocking. When the rotor core is inserted into the rotating shaft 1, it can play a buffering role to avoid the second rotor core 41 from directly contacting the first rotor core and causing extrusion and deformation.

[0061] Theoretically, in the axial direction of the rotating shaft 1, a squirrel cage rotor 4 and a permanent magnet rotor 3 are provided respectively, and the self-starting condition can be met. However, when one end is a squirrel cage rotor 4 and the other end is a permanent magnet rotor 3, the motor will generate axial force due to the imbalance of axial force during the startup process and the operation process after self-starting, which will cause many disadvantages such as abnormal noise of the motor and wear of the motor bearing. If the structure is replaced with a squirrel cage rotor 4 at one end and a permanent magnet rotor 3 at one end, then during the self-starting process of the motor, the motor only has the squirrel cage rotor 4 to provide the starting torque. Since the permanent magnet rotor 3 at the other end cannot provide an equivalent electromagnetic torque in the axial space, an axial force is generated, and vice versa. Therefore, it is designed as a three-section rotor structure. In the axial space, no matter what state the motor is in, the axial force on the motor is balanced.

[0062] In some embodiments,

[0063] The rotor assembly further includes a baffle 2 . Two baffles 2 are provided and are disposed on one end of the first rotor core away from the second rotor core 41 .

[0064] Since both sides of the three-section rotor structure are permanent magnet rotors 3, a baffle 2 structure is conventionally set on the end surface of the permanent magnet rotor 3. In the present application, a baffle 2 structure can be set at both axial ends of the three-section rotor to improve the stability of the motor operation.

[0065] In some embodiments,

[0066] The baffle plate 2 is provided with a mounting hole 21 for mounting a dynamic balancing screw. There are a plurality of mounting holes 21 , which are evenly arranged along the circumference of the baffle plate 2 .

[0067] In order to further adjust the running stability of the entire rotor core, a mounting hole 21 is provided on the baffle 2 for mounting a dynamic balancing screw, so that the motor runs more stably, has less noise and a longer service life.

[0068] In some embodiments,

[0069] The rotating shaft 1 includes an assembly section for sleeved the rotor core, one end of the assembly section is provided with a flange 11, and the other end is provided with a threaded external thread 12 and a locking nut 5; the rotor core is sleeved between the flange 11 and the locking nut 5.

[0070] Since the rotating shaft 1 is provided with three-section rotors, in order to improve the assembly efficiency and prevent the axial movement of each section of the rotor during operation, flanges 11 and external threads 12 are provided at both ends of the assembly section of the mounted rotor core, and a locking nut 5 is connected to the external thread 12. The three-section rotor is inserted between the flange 11 and the locking nut 5, and the stability of the rotor on the rotating shaft 1 is improved by screwing the locking nut 5.

[0071] In some embodiments,

[0072] The outer circumferential surface of the assembly section and the inner circumferential surface of the rotor core are both provided with key grooves for key connection.

[0073] Keyways are arranged on the circumferential surfaces of the assembly section and the rotor core, and keys are inserted to provide mechanical torque. A first keyway 13 is arranged on the rotating shaft 1, a second keyway 32 is arranged on the permanent magnet rotor 3, and a third keyway 43 is arranged on the squirrel cage rotor 4. The notches of the second keyway 32 and the third keyway 43 are both opposite to the notches of the first keyway 13, forming a through slot, and a key can be inserted into the through slot.

[0074] According to another aspect of the present application, a motor is provided, comprising the rotor assembly as described above.

[0075] The motor using the above rotor assembly can achieve the self-starting effect without the need for a frequency converter. Before reaching the rated speed, the squirrel cage rotor 4 is the one that works in the motor, and the asynchronous squirrel cage rotor 4 drives the synchronous permanent magnet rotor 3 to operate. When the slip rate gradually decreases and reaches the synchronous speed, the squirrel cage rotor 4 will no longer pass the torque, and the permanent magnet rotor 3 will provide the torque. In addition, when the load suddenly changes, the motor speed decreases, and the squirrel cage rotor 4 will provide torque again, which will provide the motor with a larger electromagnetic torque and improve the anti-interference ability of the motor.

[0076] In some embodiments,

[0077] The motor further includes a stator assembly 6 , which includes a stator core 61 . The rotor core is inserted into the stator core 61 , and along the axial direction of the stator core 61 , the length of the rotor core is greater than the length of the stator core 61 .

[0078] In the stator assembly 6 of the motor, the axial length of the stator core 61 is smaller than the axial length of the rotor core, so that part of the rotor core is exposed from the stator core 61, and there is still a magnetic field at the end winding 62 of the stator core 61. In the traditional structure of the rotor core and the stator core 61 of equal length, this part of the magnetic field is in an inactive state. The present application places the part of the rotor core exposed from the stator core 61 in the magnetic field of the end winding 62, which can effectively utilize this part of the magnetic field to achieve energy saving and efficiency improvement.

[0079] According to another aspect of the present application, a compressor is provided, comprising the rotor assembly as described above or the motor as described above.

[0080] It is easy for those skilled in the art to understand that the above-mentioned implementation modes can be freely combined and superimposed without conflict.

[0081] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A rotor assembly, characterized in that: include: A rotating shaft (1) is sleeved with a rotor core; The rotor core is provided with a first rotor core and a second rotor core (41) along the axial direction of the rotating shaft (1), and the axial length of the first rotor core is greater than the axial length of the second rotor core (41); the first rotor core is provided with a magnetic steel slot (31), and a magnetic steel (33) is provided in the magnetic steel slot (31); the second rotor core (41) is provided with a tooth slot, and a guide bar is provided in the tooth slot, and end rings (42) are provided at both ends of the guide bar.

2. The rotor assembly according to claim 1, characterized in that: Two first rotor iron cores are provided, respectively located at two axial ends of the second rotor iron core (41).

3. The rotor assembly according to claim 2, characterized in that: The rotor assembly further comprises a baffle (2), wherein two baffles (2) are provided and are arranged on one end of the first rotor core away from the second rotor core (41).

4. The rotor assembly according to claim 3, characterized in that: The baffle plate (2) is provided with a mounting hole (21) for mounting a dynamic balancing screw, and a plurality of the mounting holes (21) are provided and are evenly arranged along the circumference of the baffle plate (2).

5. The rotor assembly according to any one of claims 1 to 4, characterized in that: The rotating shaft (1) comprises an assembly section for sleeve-mounting the rotor core, one end of the assembly section is provided with a flange (11), and the other end is provided with a threaded external thread (12) and a locking nut (5); the rotor core is sleeved between the flange (11) and the locking nut (5).

6. The rotor assembly according to claim 5, characterized in that: The outer circumferential surface of the assembly section and the inner circumferential surface of the rotor core are both provided with key grooves for key connection.

7. A motor, characterized in that: Comprising a rotor assembly as described in any one of claims 1-6.

8. The motor according to claim 7, characterized in that: The motor further comprises a stator assembly (6), the stator assembly (6) comprising a stator core (61), the rotor core is inserted into the stator core (61), and along the axial direction of the stator core (61), the length of the rotor core is greater than the length of the stator core (61).

9. A compressor, characterized in that: It comprises the rotor assembly according to any one of claims 1 to 6 or the motor according to any one of claims 7 to 8.

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