Squirrel cage rotors, motors and electrical products

Abstract

The present invention provides a squirrel cage rotor, motor, and electrical product, relating to the field of motor technology. It solves the technical problem in the prior art that the skewed slots of squirrel cage rotors increase the rotor leakage resistance, thereby affecting the motor performance. The squirrel cage rotor comprises a rotor core and a squirrel cage; the rotor core is provided with guide bar slots parallel to the axis of the rotor core; the guide bar slots are arranged in multiple intervals along the axial direction of the rotor core, and the guide bar slots in each interval are staggered; the squirrel cage comprises guide bars and connecting rings, the guide bars are arranged in the guide bar slots to form an interval multi-section structure, and the multiple interval guide bars are connected by the connecting rings. The present invention adopts a guide bar slot structure parallel to the axis of the rotor core to solve the leakage resistance problem caused by the skewed slot rotor. At the same time, the segmented staggered guide bar structure weakens the tooth harmonics, reduces the additional torque, vibration, and noise caused by the tooth harmonics, and improves the motor performance.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a squirrel cage rotor, a motor and an electrical product. Background Art

[0002] A squirrel-cage motor is a three-phase asynchronous motor whose rotor winding is not wound with insulated wire, but rather welded or cast aluminum or copper bars with short-circuit rings. Squirrel-cage motors are widely applicable and offer advantages such as simple structure, durability, reliable operation, and easy maintenance. The rotor used in a squirrel-cage motor is called a squirrel-cage rotor.

[0003] The main pole magnetic field of an AC motor is generally not sinusoidally distributed in the air gap. In addition to the fundamental wave, there are many higher harmonics. Among the harmonics, the amplitude of the first-order tooth harmonic is the largest, which has a significant impact on the performance of the motor. In existing squirrel cage rotors, the rotor generally adopts a skewed slot structure, such as Figure 1 As shown, the distance between the skew slots is generally the distance of one stator slot to reduce the impact of tooth harmonics on motor performance.

[0004] The applicant has discovered that the prior art has at least the following technical problems:

[0005] In the prior art, the skewed slots of the squirrel-cage rotor increase the rotor leakage reactance, thereby reducing the maximum torque and power factor of the motor and affecting the motor performance. Summary of the Invention

[0006] The present invention aims to provide a squirrel-cage rotor, motor, and electrical product to address the prior art technical problem that the skewed slots of squirrel-cage rotors increase the rotor leakage reactance, thereby reducing the maximum torque and power factor of the motor and affecting motor performance. The various technical effects achieved by preferred technical solutions among the various technical solutions provided by the present invention are detailed below.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] The present invention provides a squirrel cage rotor, comprising a rotor core and a squirrel cage; the rotor core is provided with guide bar slots parallel to the axis of the rotor core; the guide bar slots are arranged into multiple sections at intervals along the axial direction of the rotor core, and the guide bar slots in each section are staggered with each other; the squirrel cage comprises guide bars and connecting rings, the guide bars are arranged in the guide bar slots to form a multiple-section structure at intervals, and the multiple sections of guide bars are connected by the connecting rings.

[0009] Optionally, the number of grooves of the guide bar grooves in each section is the same.

[0010] Optionally, the staggered angle a between two adjacent sections of the guide grooves satisfies the relationship Wherein Q is the number of grooves of the guide bar groove, and c is the number of segments of the guide bar groove.

[0011] Optionally, the staggered angles a between two adjacent sections of the guide grooves are the same.

[0012] Optionally, the outer diameter of the connecting ring is equal to the outer diameter of the rotor core, and the inner diameter of the connecting ring is equal to the inner diameter of the rotor core.

[0013] Optionally, the height h of the connecting ring satisfies the relationship Wherein, L is the length of the rotor core, Q is the number of the guide bar slots, and c is the number of the sections of the guide bar slots.

[0014] Optionally, the height h of the connecting rings in each section is the same.

[0015] Optionally, the outer diameter of the connecting ring is equal to the outer diameter of the rotor core, and the inner diameter of the connecting ring is greater than the inner diameter of the motor shaft.

[0016] Optionally, the guide bars and the connecting rings are made of aluminum or copper.

[0017] A motor includes a squirrel cage rotor, wherein the squirrel cage rotor is any of the squirrel cage rotors described above.

[0018] An electrical product includes a motor, wherein the motor is the motor described above.

[0019] Any of the above technical solutions can at least produce the following technical effects:

[0020] This invention utilizes a bar slot structure parallel to the axis of the rotor core, addressing the leakage reactance issues associated with skewed slot rotors and preventing the impact of leakage reactance on the motor's maximum torque and power factor. Furthermore, the multi-segmented bar structure divides the entire bar segment that originally generates tooth harmonics into multiple segments. This reduces the resulting electromotive force induced on the segmented bar, while also offsetting the segments, which together cancel out the motor's harmonic magnetomotive force. Consequently, the staggered bar structure weakens tooth harmonics, reducing the additional torque, vibration, and noise caused by these harmonics, and improving motor performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 these drawings without paying any creative work.

[0022] Figure 1 is a schematic diagram of an existing squirrel cage rotor structure;

[0023] Figure 2 is a schematic diagram of the rotor core;

[0024] Figure 3 It is a schematic diagram of a rat cage;

[0025] Figure 4 is a schematic diagram of a squirrel cage rotor.

[0026] In the figure, 1 is the rotor core; 11 is the guide bar slot; 11a is the first section of the guide slot; 11b is the second section of the guide slot; 2 is the squirrel cage; 21 is the guide bar; 22 is the connecting ring; 23 is the end ring; 24 is the fan blade; 3 is the motor shaft. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0028] The present invention provides a squirrel cage rotor, the rotor winding of which is not wound by insulating wires, but is welded or cast by metal strips and short-circuit rings. Figure 2-4 As shown, the rotor core 1 and the cage 2 are provided on the outside of the rotor core 1. The outer circumference of the rotor core 1 is provided with guide bar slots 11 parallel to the axis of the rotor core 1. That is, the geometric axis of the guide bar slots 11 is parallel to the axis of the rotor core. In contrast, the skewed slots of the existing skewed slot cage rotor are not aligned with the axis of the rotor core 1. The existing cage rotor has only one skewed slot, and the guide bar slots 11 are provided in multiple intervals along the axial direction of the rotor core 1. At the same time, the guide bar slots 11 of each segment are staggered, as shown in FIG. Figure 2 The figure shows a two-section guide groove 11 structure, the solid line portion of the guide groove 11 is the first section of the guide groove 11a, the dotted line portion of the guide groove 11 is the second section of the guide groove 11b, and the two are staggered at a certain angle. The specific number of grooves in each section of the guide groove 11 is set as needed, such as Figure 2The number shown is 30, but other numbers, such as 40 or 56, can also be selected as needed. The cage 2 includes conductive bars 21 and connecting rings 22. The cage 2 needs to pass current, and the conductive bars 21 and connecting rings 22 are preferably made of metal. The shape of the conductive bars 21 matches the shape of the conductive bar slots 11, and the number of conductive bars 21 is the same as the number of conductive bar slots 11. Since the conductive bar slots 11 are spaced apart in multiple sections, the conductive bars 21 arranged in the conductive bar slots 11 also form a spaced multi-section structure. The spaced multi-section conductive bars 21 are connected by connecting rings 22, achieving interconnection between the conductive bars 21. After the conductive bars 21 at the two ends of the cage 2 are connected to the end rings 23, the conductive bars 21, connecting rings 22, and end rings 23 together form a short-circuited closed coil, which acts as an induction current and enables the motor to operate, thus forming the cage 2 structure. It is preferred that the lengths of the conductive bar slots 11 of each section are the same to facilitate manufacturing and production, and to better offset the harmonic magnetomotive forces generated between the conductive bars 21 of each section. The increased reactive component in the radial direction of the bars in a skewed rotor increases the leakage reactance of the skewed slots, reducing the motor's torque and power factor. By replacing the squirrel-cage rotor's skewed slot structure with bar slots 11 parallel to the axis of the rotor core 1, the leakage reactance problem associated with the skewed rotor is resolved, eliminating the resulting low torque and power factor. Furthermore, the multi-segment structure of the bars 21 divides the entire section of bars that originally generated tooth harmonics into multiple sections. This reduces the resulting composite potential induced on the bars 21 after segmentation, while also offsetting the harmonic magnetomotive forces of the bars 21. Consequently, the staggered sections of the bars 21 weaken the tooth harmonics, reducing the additional torque, vibration, and noise caused by these harmonics, and improving motor performance.

[0029] As an optional implementation, the number of slots in each section of the conductive bar slots 11 is the same, and the number of corresponding conductors 21 in each section is also the same. For example, the number of conductive bar slots 11 and conductive bars 21 in each section is 30, 40, 56, etc., thereby achieving better mutual cancellation of the harmonic magnetomotive force generated between the conductive bars 21 in each section.

[0030] As an optional embodiment, the staggered angle a between two adjacent sections of the guide groove 11 satisfies the relationship Where Q is the number of grooves in the guide groove 11, and c is the number of segments in the guide groove 11. Figure 2 As shown, the stagger angle a is the angle between the center of the cross section of the rotor core 1 and the line connecting the guide slot axis. Figure 2As shown, the guide groove 11 is divided into two sections, i.e. c = 2, and the number of grooves of the guide groove 11 is 30, i.e. Q = 30. The staggered angle between two adjacent guide grooves 11 in the same section is calculated to be 12°. Substituting π = 180°, the staggered angle a of the two sections of the guide groove 11 satisfies the relationship of 2°≤a≤6°. The axis of one section of the guide groove 11 is located near the angle bisector of the axes of the two adjacent guide grooves 11 in the other section. Within this staggered angle range, the best harmonic reduction effect can be achieved. When c>2, the staggered angle between two adjacent guide grooves 11 in the same section is The sum of the staggered angles of the guide grooves 11 between the multiple sections of the guide grooves 11 will not exceed It is preferred that the staggered angles a between two adjacent sections of the guide bar grooves 11 are the same, which is more convenient for manufacturing and can achieve a better harmonic reduction effect. Therefore, the staggered angles a between two adjacent sections of the guide bar grooves 11 satisfy the relationship The harmonic magnetomotive forces between the sections of the guide grooves 11 can be better offset each other, thereby achieving a better harmonic weakening effect and effectively reducing the additional torque, vibration and noise of the motor caused by the harmonics.

[0031] As an optional embodiment, the outer diameter of the connecting ring 22 is equal to the outer diameter of the rotor core 1, and the inner diameter of the connecting ring 22 is equal to the inner diameter of the rotor core 1. Figure 4 As shown, the connecting ring 22 directly replaces the corresponding space of the original rotor core 1. The inner side of the connecting ring 22 contacts the motor shaft 3 of the motor, and the outer side of the connecting ring 22 is the air gap of the motor, which is convenient for production and manufacturing. The height h of the connecting ring 22 satisfies the relationship Wherein L is the length of the rotor core 1, Q is the number of the guide bar slots, and c is the number of sections of the guide bar slots 11. Figure 4 As shown, the height h of the connecting ring 22 is the length of the connecting ring 22 occupied by the rotor core 1. The circumference of the outer circumference of the rotor core 1 is first divided into Q segments, and the total height h of the connecting ring 22 in segment C will not exceed However, being close to this value will not have a significant impact on the rotor core 1, and can increase the surface area of ​​the squirrel cage 2. It is preferred that the height h of each section of the connecting ring 22 is the same, which is convenient for production and manufacturing, and also facilitates better heat dissipation of the motor. The connecting ring 22 directly replaces the space corresponding to the original rotor core 1. The metal materials commonly used for the connecting ring 22, such as copper and aluminum, have poor magnetic conductivity relative to the silicon steel of the rotor core 1. The height value of the connecting ring 22 should not be too large. When the height h of the connecting ring satisfies this relationship, the loss can be reduced. The surface area of ​​the connecting ring 22 is increased compared to the existing skewed slot guide bars, which reduces the resistance of the entire squirrel cage rotor and reduces rotor losses. At the same time, the connecting ring 22 is in direct contact with the air gap of the motor, which dissipates heat faster in the rotor, reducing losses during the operation of the motor. When the squirrel cage is cast aluminum, it is aluminum loss.

[0032] As an optional embodiment, the outer diameter of the connecting ring 22 is equal to the outer diameter of the rotor core 1, and the inner diameter of the connecting ring 22 is greater than the outer diameter of the motor shaft 3. The diameter of the cross-sectional circle of the rotor core 1 at the corresponding position of the connecting ring 22 is appropriately reduced, such as 3-5mm (the diameter of the silicon steel sheet of the rotor core 1 at this position can be selected to be 3-5mm smaller than the silicon steel sheet of the rotor core 1 at other positions, and the height of the connecting ring 22 is the same as the length of the silicon steel sheet at this position after being stacked). After stacking with other silicon steel sheets of normal size, the rotor core 1 will leave a circular groove at this position, and the connecting ring 22 matches the circular groove. The inner side of the connecting ring 22 contacts the outer circumference of the rotor core 1, and the inner diameter is greater than the outer diameter of the motor shaft 3. The outer side of the connecting ring 22 is the air gap of the motor, and the outer diameter is equal to the outer diameter of the rotor core 1. Preferably, the height of the connecting ring 22 is greater than the width of the guide bar slot 11. The connecting ring 22 of this structure can minimize the increase in losses caused by the poor magnetic conductivity of the connecting ring 22 compared to the silicon steel sheet; the surface area of ​​the connecting ring 22 is increased compared to the existing skewed slot guide bar, which reduces the resistance of the entire squirrel cage rotor and reduces rotor losses; at the same time, the connecting ring 22 is in direct contact with the air gap of the motor, which speeds up the heat dissipation of the rotor and reduces the losses during the operation of the motor.

[0033] As an optional embodiment, the guide bar 21 and the connecting ring 22 are made of aluminum or copper. Aluminum is relatively inexpensive, but its conductivity is poorer than copper. Copper has high conductivity and can reduce motor losses, but it is relatively expensive. The guide bar 21 and the connecting ring 22 are integrally formed or connected by welding. When the guide bar 21 and the connecting ring 22 are made of aluminum, the guide bar 21 and the connecting ring 22 are integrally formed, and the integral structure of the guide bar 21 and the connecting ring 22 is formed by casting, that is, by casting aluminum, which is easy to manufacture. When the guide bar 21 and the connecting ring 22 are made of copper, integral casting is relatively inconvenient, and they can be fixed by welding.

[0034] As an optional embodiment, Figure 4 As shown, cage 2 also includes blades 24 at both ends. Blades 24 are integrally formed with or welded to cage 2. Blades 24 are specifically connected to end rings 23. When cage 2 is made of cast aluminum, blades 24, guide bars 21, connecting rings 22, and end rings 23 can be integrally formed from molten aluminum. When cage 2 is made of copper, blades 24 are secured to end rings 23 by welding. Blades 24 provide internal ventilation and heat dissipation for the motor, thereby reducing motor temperature rise. Blades 24 are multiple straight blades spaced circumferentially around end rings 23 and extending radially. These blades are relatively simple in shape and structure, making them easy to manufacture.

[0035] A motor includes a squirrel cage rotor, the squirrel cage rotor being the squirrel cage rotor of the present invention. The squirrel cage rotor of the present invention solves the leakage inductance problem caused by the skewed slot rotor, and the maximum torque and power factor of the motor are not affected by the leakage inductance. Simultaneously, the multi-segment structure of the conductor bar 21 divides the entire conductor bar that originally generates tooth harmonics into multiple segments. On the one hand, the synthetic potential induced on the segmented conductor bar 21 is reduced. On the other hand, the conductor bars 21 of each segment are staggered relative to each other, thereby mutually canceling out the harmonic magnetomotive force of the motor. Therefore, the segmented and staggered conductor bar 21 structure weakens the tooth harmonics, reduces the additional torque, vibration, and noise caused by the tooth harmonics, and improves the performance of the motor.

[0036] An electrical appliance includes a motor, wherein the motor is the motor of the present invention. Since the motor reduces additional torque, vibration, and noise caused by tooth harmonics, the performance of the electrical appliance is improved and the comfort of using the electrical appliance is increased.

[0037] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A squirrel cage rotor, characterized in that: The invention comprises a rotor core and a squirrel cage; the rotor core is provided with guide bar slots parallel to the axis of the rotor core; the guide bar slots are arranged in multiple sections along the axial direction of the rotor core, and the guide bar slots in each section are staggered; the squirrel cage comprises guide bars and connecting rings, the guide bars are arranged in the guide bar slots to form a multiple-section structure, and the multiple sections of guide bars are connected by the connecting rings; The number of guide grooves in each section is the same; The staggered angle a between two adjacent sections of the guide grooves satisfies the relationship Wherein Q is the number of grooves of the guide groove, and c is the number of segments of the guide groove; The outer diameter of the connecting ring is equal to the outer diameter of the rotor core, and the inner diameter of the connecting ring is equal to the inner diameter of the rotor core; The height h of the connecting ring satisfies the relationship Wherein, L is the length of the rotor core, Q is the number of the guide bar slots, and c is the number of the sections of the guide bar slots.

2. The squirrel cage rotor according to claim 1, characterized in that: The staggered angles a between two adjacent sections of the guide grooves are the same.

3. The squirrel cage rotor according to claim 1, characterized in that: The height h of the connecting rings in each section is the same.

4. The squirrel cage rotor according to claim 1, characterized in that: The outer diameter of the connecting ring is equal to the outer diameter of the rotor core, and the inner diameter of the connecting ring is greater than the inner diameter of the motor shaft.

5. The squirrel cage rotor according to claim 1, characterized in that: The guide bars and the connecting rings are made of aluminum or copper.

6. A motor comprising a squirrel cage rotor, characterized in that: The squirrel cage rotor is the squirrel cage rotor described in any one of claims 1-5.

7. An electrical product, comprising a motor, characterized in that: The motor is the motor according to claim 6.

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