A permanent magnet motor rotor structure used in a permanent magnet motor to increase critical speed

Abstract

The present invention provides a permanent magnet motor rotor structure that can be used in a permanent magnet motor to increase the critical speed, and belongs to the technical field of permanent magnet motors. The rotor core of the present invention is provided with a pressure ring at both ends, and the punching sheets of the rotor core are separated by a ventilation slot plate, and the ventilation slot plate is tightened and fixed by screws and nuts, and nuts are installed at both ends of the pull rod. The pull rod passes through the rotor core, the ventilation slot plate and the pressure ring and is fastened by nuts. The rotor core and the shaft have an interference fit, and the rotor core is stacked and pre-tightened and then hot-mounted on the shaft as a whole. Under the premise of not changing the shaft diameter, the present invention changes the structure of the rotor core and uses a suitable process method to enable the rotor core to have the effect of enhancing the rigidity of the rotating shaft.

Description

Technical Field

[0001] The invention relates to a permanent magnet motor rotor structure which is applied in a permanent magnet motor and can improve the critical speed, and belongs to the technical field of permanent magnet motors. Background Art

[0002] Permanent magnet motors use permanent magnets to provide excitation, which makes the motor structure simpler, reduces processing and assembly costs, and improves the reliability of motor operation. Because no excitation current is required and there is no excitation loss, the efficiency and power density of the motor are improved, making it a type of motor that is increasingly widely used in various fields.

[0003] The conventional iron core structure in the current permanent magnet motor cannot play a (or plays a very small) rigid strengthening effect because the punching sheets are a laminated structure. In addition, the rotor ventilation slot plate is in the shape of a bead, and the bead shape needs to be welded. If the welding is not done well, it will cause failure and cause accidents. Welding requires many welding points and there is not enough space. Summary of the invention

[0004] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art and further provide a permanent magnet motor rotor structure which can be used in a permanent magnet motor and can increase the critical speed.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A permanent magnet motor rotor structure used in a permanent magnet motor to increase the critical speed includes: a rotor core, a ventilation slot plate, a pressure ring, screws, nuts, a pull rod and a shaft,

[0007] Among them, pressure rings are arranged at both ends of the rotor core, the punching sheets of the rotor core are separated by ventilation slot plates, the ventilation slot plates are tightened and fixed by screws and nuts, nuts are installed at both ends of the pull rod, the pull rod passes through the rotor core, ventilation slot plates and pressure rings and is tightened by nuts, the rotor core and the shaft are interference fit, and the rotor core is integrally hot-mounted on the shaft after being stacked and pre-tightened;

[0008] The ventilation slot plate includes a ventilation slot plate with threaded holes and a ventilation slot plate without threaded holes. The ventilation slot plate with threaded holes is provided with threaded holes, and the ventilation slot plate without threaded holes is provided with through holes corresponding to the threaded holes on the ventilation slot plate with threaded holes. After the screws and nuts are tightened, they are threadedly connected with the threaded holes of the ventilation slot plate with threaded holes. The through holes on the ventilation slot plate without threaded holes correspond to the screw heads on the ventilation slot plate with threaded holes, and the ventilation slot plate without threaded holes and the ventilation slot plate with threaded holes are pressed against each other.

[0009] Pull rods are arranged at the outer diameter and the center of the rotor core punching sheet.

[0010] After the screw is screwed into the nut, it is glued with anti-loosening glue and then screwed into the ventilation slot plate with threaded holes.

[0011] After the ventilation slot plate with threaded holes and the ventilation slot plate without threaded holes are assembled, the threaded holes are aligned with the through holes.

[0012] The ventilation slot plate is made of austenitic steel plate.

[0013] The material of the pressing ring is austenite material.

[0014] The beneficial effects of the present invention are:

[0015] The permanent magnet motor rotor structure of the present invention has a critical speed that is usually a fixed value. The conventional method for increasing the critical speed is often to adjust the diameter of the shaft to enhance the rigidity and increase the critical speed. However, the present invention, without changing the shaft diameter, changes the structure of the rotor core and uses a suitable process method to enable the rotor core to have the effect of enhancing the rigidity of the shaft.

[0016] The present invention solves the problem that the rotor ventilation slot plate in the traditional motor is in the shape of a pressure strip, and the pressure strip shape needs to be formed by welding. Welding requires many welding points. If the welding is not good, failure will occur, causing accidents. The present invention adopts screwing nuts to fix, and the punching sheets are stacked and pressed, but a pressure plate is arranged in the middle, which is fastened and fixed by threads, and does not require welding, thereby improving reliability. In addition, this structure is suitable for permanent magnet motors. The rotor core of permanent magnet motors has transverse strip-shaped slots, but traditional motors do not have enough space. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a schematic structural diagram of a permanent magnet motor rotor structure used in a permanent magnet motor to increase the critical speed.

[0018] Figure 2 The present invention is a schematic diagram of a non-welded rotor ventilation slot plate structure of a permanent magnet motor rotor structure which is applied in a permanent magnet motor and can increase the critical speed.

[0019] Figure 3 The present invention is a schematic side view of a non-welded rotor ventilation slot plate structure of a permanent magnet motor rotor structure used in a permanent magnet motor to increase the critical speed.

[0020] Figure 4 For the present invention Figure 3 A locally enlarged structural diagram.

[0021] Figure 5 This is a physical picture of a conventional structure rotor.

[0022] Figure 6 This is a physical diagram of a permanent magnet motor rotor structure used in a permanent magnet motor to increase the critical speed according to the present invention.

[0023] The reference numerals in the figure are: 1 is the rotor core, 2 is the ventilation slot plate, 2-1 is the ventilation slot plate with threaded holes, 2-2 is the ventilation slot plate without threaded holes, 3 is the pressure ring, 4 is the screw, 5 is the nut, 6 is the pull rod, and 7 is the shaft. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method is given, but the protection scope of the present invention is not limited to the following embodiments.

[0025] like Figures 1 to 4 As shown, the present embodiment involves a permanent magnet motor rotor structure used in a permanent magnet motor to improve the critical speed, comprising: a rotor core 1, a ventilation slot plate 2, a pressure ring 3, a screw 4, a nut 5, a pull rod 6 and a shaft 7,

[0026] Among them, pressure rings 3 are arranged at both ends of the rotor core 1, and the punching sheets of the rotor core 1 are separated by ventilation slot plates 2, and the ventilation slot plates 2 are tightened and fixed by screws 4 and nuts 5. Nuts 5 are installed at both ends of the pull rod 6, and the pull rod 6 passes through the rotor core 1, the ventilation slot plates 2 and the pressure ring 3 and is tightened by nuts 5. The rotor core 1 and the shaft 7 have an interference fit, and the rotor core 1 is integrally heat-mounted on the shaft 7 after being stacked and pre-tightened;

[0027] The ventilation slot plate 2 includes a ventilation slot plate 2-1 with threaded holes and a ventilation slot plate 2-2 without threaded holes. The ventilation slot plate 2-1 with threaded holes is provided with threaded holes, and the ventilation slot plate 2-2 without threaded holes is provided with through holes corresponding to the threaded holes on the ventilation slot plate 2-1 with threaded holes. After tightening, the screws 4 and nuts 5 are threadedly connected with the threaded holes of the ventilation slot plate 2-1 with threaded holes. The through holes on the ventilation slot plate 2-2 without threaded holes correspond to the heads of the screws 4 on the ventilation slot plate 2-1 with threaded holes, and the ventilation slot plate 2-2 without threaded holes and the ventilation slot plate 2-1 with threaded holes are pressed against each other.

[0028] Pull rods 6 are provided at the outer diameter and the center of the rotor core 1 punching sheets.

[0029] The screw 4 is screwed into the nut 5 and fixed with anti-loosening glue, and then screwed into the ventilation slot plate 2-1 with threaded holes.

[0030] After the ventilation slot plate with threaded holes 2-1 and the ventilation slot plate without threaded holes 2-2 are assembled, the threaded holes are aligned with the through holes.

[0031] The ventilation slot plate 2 is made of austenitic steel plate.

[0032] The material of the pressing ring 3 is austenite material.

[0033] Example 1

[0034] like Figure 1As shown, a pressing ring 3 is provided at both ends of the rotor core 1, and the punching sheets of the rotor core 1 are separated by a ventilation slot plate 2, and the ventilation slot plate 2 is tightened and fixed by screws 4 and nuts 5, and nuts 5 are installed at both ends of the pull rod 6, and the pull rod 6 passes through the rotor core 1, the ventilation slot plate 2 and the pressing ring 3 and is fastened by nuts 5, and the rotor core 1 is interference fit with the shaft 7, and the rotor core 1 is integrally heat-mounted on the shaft 7 after being stacked and pre-tightened;

[0035] like Figure 2 , Figure 3 As shown, the ventilation slot plate 2 includes a ventilation slot plate 2-1 with threaded holes and a ventilation slot plate 2-2 without threaded holes. The ventilation slot plate 2-1 with threaded holes is provided with threaded holes, and the ventilation slot plate 2-2 without threaded holes is provided with through holes corresponding to the threaded holes on the ventilation slot plate 2-1 with threaded holes, as shown in FIG. Figure 4 As shown, after the screws 4 and nuts 5 are tightened, they are threadedly connected with the threaded holes of the ventilation slot plate 2-1 with threaded holes. After the threaded holes and the screws 4 are tightened, the gap is extremely small, no shaking will occur, and the fixing effect is good. The through holes on the ventilation slot plate 2-2 without threaded holes correspond to the heads of the screws 4 on the ventilation slot plate 2-1 with threaded holes, and the ventilation slot plate 2-2 without threaded holes and the ventilation slot plate 2-1 with threaded holes are pressed against each other.

[0036] Conventional rotor core structures cannot play a (or play a very small) rigidity strengthening effect because the punching sheets are stacked. In the structure involved in this embodiment, there are austenitic pressure rings 3 at both ends of the rotor core 1, and the punching sheets are separated by ventilation slot plates 2 made of austenitic material. The ventilation slot plates 2 are not welded with I-shaped ventilation slot steel, but are fixed by tightening austenitic steel plates with screws 4 and nuts 5. The rotor core 1 is tightened as a whole with nuts 4 and tie rods 6 (there are tie rods near the outer diameter and the center of the punching sheets) to ensure the stacking coefficient and preload. The rotor core 1 and the shaft 7 are interference fit. After stacking and preloading, the rotor core 1 is hot-mounted on the shaft 7 as a whole. As the rotor heats up during operation, the preload force of the rotor core 1 itself will increase again, and the rigidity of the rotor will be enhanced, achieving the effect of increasing the critical speed.

[0037] In the existing permanent magnet motor, the permanent magnets are embedded in the rotor, which occupies a certain space. The I-shaped ventilation slot steel near the permanent magnets is too short and can only be spot welded, which greatly reduces the reliability. However, the rotor ventilation slot plate 2 in this embodiment is fixed by screws 4 and nuts 5, which ensures sufficient support. Because no welding structure is used, the reliability of operation is greatly improved.

[0038] like Figure 5 , Figure 6 As shown, conventional rotor laminations will produce large tooth expansion when they are stacked, while the rotor structure of this embodiment can effectively reduce the tooth expansion of the rotor laminations. The pre-tightening pressure between the laminations is maintained, so that the laminations have good integrity, thereby improving the rigidity of the rotor and achieving the effect of increasing the critical speed.

[0039] Example 2

[0040] Test method:

[0041] The natural frequency of the rotor (same center height, same power, different rotor structure) is tested by the knocking method. The signal of knocking the rotor is measured by the vibration sensor. After signal processing, the first-order natural frequency of the rotor is measured. The test results are shown in Table 1.

[0042] Table 1

[0043] Serial number project Natural frequency test value Remark 1 450-4 Rotor 1 67.2Hz Conventional structure rotor 2 450-4 Rotor 2 81.7Hz The rotor structure of this embodiment 3 1600-4 rotor 1 53.6Hz Conventional structure rotor 4 1600-4 rotor 2 60.8Hz The rotor structure of this embodiment

[0044] As can be seen from Table 1, the natural frequency of the rotor using the patented structure is significantly improved compared with the conventional structure rotor. It can be determined that the rotor core has an effective rigidity enhancement effect on the shaft, thereby increasing the critical speed of the rotor.

[0045] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A permanent magnet motor rotor structure used in a permanent magnet motor to increase the critical speed, characterized in that: include: A rotor core (1), a ventilation slot plate (2), a pressure ring (3), a screw (4), a nut (5), a tie rod (6) and a shaft (7); Wherein, pressure rings (3) are arranged at both ends of the rotor core (1), the punching sheets of the rotor core (1) are separated by ventilation slot plates (2), the ventilation slot plates (2) are tightened and fixed by screws (4) and nuts (5), nuts (5) are installed at both ends of the pull rod (6), the pull rod (6) passes through the rotor core (1), the ventilation slot plates (2) and the pressure ring (3) and is tightened by nuts (5), the rotor core (1) and the shaft (7) are interference fit, and the rotor core (1) is integrally heat-mounted on the shaft (7) after being stacked and pre-tightened; The ventilation slot plate (2) comprises a ventilation slot plate with threaded holes (2-1) and a ventilation slot plate without threaded holes (2-2); the ventilation slot plate with threaded holes (2-1) is provided with threaded holes, and the ventilation slot plate without threaded holes (2-2) is provided with through holes corresponding to the threaded holes on the ventilation slot plate with threaded holes (2-1); the screws (4) and nuts (5) are threadedly connected with the threaded holes of the ventilation slot plate with threaded holes (2-1) after being tightened; the through holes on the ventilation slot plate without threaded holes (2-2) correspond to the heads of the screws (4) on the ventilation slot plate with threaded holes (2-1); and the ventilation slot plate without threaded holes (2-2) and the ventilation slot plate with threaded holes (2-1) are pressed against each other.

2. A permanent magnet motor rotor structure for increasing critical speed used in a permanent magnet motor according to claim 1, characterized in that: Pull rods (6) are provided at the outer diameter and the center of the rotor core (1) punching sheet.

3. A permanent magnet motor rotor structure for increasing critical speed used in a permanent magnet motor according to claim 1, characterized in that: The screw (4) is screwed into the nut (5) and then fixed with anti-loosening glue, and then screwed into the ventilation slot plate (2-1) with threaded holes.

4. A permanent magnet motor rotor structure for increasing critical speed in a permanent magnet motor according to claim 1, characterized in that: After the ventilation slot plate with threaded holes (2-1) and the ventilation slot plate without threaded holes (2-2) are assembled, the threaded holes are aligned with the through holes.

5. The permanent magnet motor rotor structure for increasing the critical speed used in a permanent magnet motor according to claim 1, characterized in that: The ventilation slot plate (2) is made of austenitic steel plate.

6. A permanent magnet motor rotor structure for increasing critical speed used in a permanent magnet motor according to claim 1, characterized in that: The material of the pressing ring (3) is austenite material.

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