A super-high-speed asynchronous motor rotor bar fixing structure

Abstract

This invention belongs to the field of motor manufacturing technology and discloses a rotor guide bar fixing structure for an ultra-high-speed asynchronous motor. The structure includes a solid rotor body and rotor guide bars. Multiple guide bar mounting slots are formed on the outer periphery of the solid rotor body. Each guide bar mounting slot houses and fixes a rotor guide bar, which has an outwardly protruding arc-shaped protrusion in its center. The shape of the guide bar mounting slot matches the shape of the rotor guide bar and satisfies the following fit relationships: a clearance fit in the width direction; an interference fit in the height direction; and at least three non-collinear contact positioning surfaces are formed between the rotor guide bar and the corresponding guide bar mounting slot. These three contact positioning surfaces constrain the radial, circumferential, and axial degrees of freedom of the rotor guide bar. This ultra-high-speed asynchronous motor rotor guide bar fixing structure uses rotor guide bars with a central protrusion for fixing, achieving complete positioning and effectively ensuring reliable rotor fixation under high speed and overspeed conditions.

Description

Technical Field

[0001] This invention belongs to the field of motor manufacturing technology, specifically relating to a rotor guide bar fixing structure for an ultra-high-speed asynchronous motor. Background Technology

[0002] The normal operating speed of a conventional industrial asynchronous motor is around 3000 rpm. Due to the relatively low linear velocity of the rotor surface, a conventional laminated rotor core with a heat-shrinkable shaft is sufficient, with an interference fit between the inner circle of the rotor core and the motor shaft. As the speed increases, such as to 5000-6000 rpm, a larger interference fit is required between the inner circle of the rotor core and the motor shaft. High-strength silicon steel sheets are typically used, while still ensuring the reliability of the rotor structure.

[0003] Please see Figures 1 to 7 The inner circle of the rotor core 2′ and the motor shaft 1′ are fitted with an interference fit. Conventional laminated rotor cores typically use rectangular cross-section rotor bars 3′. Considering the stress on the bars and the motor performance requirements, copper or aluminum busbars are sufficient. A guide bar mounting slot 21′ is provided on the rotor core, and the fit between the slot and the rotor guide bar 3′ is a transition fit or clearance fit, facilitating guide bar installation. Due to potential clearance, after the rotor guide bar 3′ is installed, a cage expansion is required at the opening of the guide bar mounting slot 21′. A stamping tool is used to punch a groove 31′ on the rotor guide bar 3′ with a depth a of 3mm, a width b of 2.5mm, and a length c of 20mm. One groove 31′ is provided every 2-3 sections of the core on each rotor guide bar 3′ (see...). Figures 6 to 7 The punch groove 31' compresses and deforms the rotor guide bar 3', thereby tightening the rotor guide bar 3' with the guide bar mounting groove 21', avoiding quality problems such as motor vibration caused by the loosening of the rotor guide bar 3' during operation.

[0004] When the motor speed increases further, for example, from a rated speed of 9500 rpm to overspeed speeds reaching 11000 rpm, conventional laminated rotor cores cannot meet the strength requirements, necessitating a solid rotor structure where the rotor core and shaft are integrated, using high-strength magnetic alloy steel. In this case, the mounting slots for the rotor bars are machined from the shaft. Consequently, the strength of existing copper or aluminum bar conductors is insufficient, requiring the use of high-strength alloy copper. The high hardness of alloy bars makes the conventional bar expansion process impractical. Furthermore, the existing method of fixing the rotor bars to the rotor core cannot guarantee a secure connection, necessitating the development of a new rotor bar fixing structure. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a rotor guide bar fixing structure for an ultra-high speed asynchronous motor. The rotor guide bar with a raised center is used for fixing, which achieves complete positioning in the circumference, radial direction and axial direction, and can effectively ensure that the rotor is firmly fixed at high speed and overspeed conditions.

[0006] The technical solution to achieve the above objective is: a rotor guide bar fixing structure for an ultra-high-speed asynchronous motor, comprising a solid rotor body and rotor guide bars, wherein: The outer periphery of the solid rotor body is provided with multiple guide bar mounting slots; Each guide bar mounting slot is fitted with and fixed with one of the rotor guide bars, and the middle of the rotor guide bar has an outwardly protruding arc-shaped protrusion; The shape of the guide bar mounting groove matches the shape of the rotor guide bar, and satisfies the following fit relationship: In the width direction, the width dimension of the rotor guide bar is smaller than the corresponding width dimension of the guide bar mounting groove, forming a clearance fit; In the height direction, the height dimension between the top of the arc-shaped protrusion of the rotor guide bar and the bottom surface of the rotor guide bar is greater than the corresponding height dimension of the guide bar mounting groove, forming an interference fit; At least three non-collinear contact positioning surfaces are formed between the rotor guide bar and the corresponding guide bar mounting groove. The three contact positioning surfaces constrain the radial, circumferential and axial degrees of freedom of the rotor guide bar to achieve complete positioning.

[0007] The aforementioned rotor guide bar fixing structure for an ultra-high-speed asynchronous motor, wherein the three contact positioning surfaces include: Two contact positioning surfaces located on the two inclined surfaces on the upper part of the arc-shaped protrusion of the rotor guide bar; and a contact positioning surface located on the bottom surface of the rotor guide bar.

[0008] In the aforementioned ultra-high-speed asynchronous motor rotor guide bar fixing structure, the interference fit is achieved through a heat fitting process: after heating and heat preservation of the solid rotor body, the rotor guide bar at room temperature is inserted into the guide bar mounting groove; after the solid rotor body cools down, the interference fit is formed in the height direction by thermal expansion and contraction.

[0009] In the above-mentioned ultra-high speed asynchronous motor rotor guide bar fixing structure, the two corners of the bottom surface of the rotor guide bar are rounded, and the two corners of the bottom end of the guide bar mounting groove are rounded.

[0010] The aforementioned rotor guide bar fixing structure for an ultra-high-speed asynchronous motor, wherein the rotor guide bar is made of high-strength alloy copper material.

[0011] The aforementioned rotor guide bar fixing structure for an ultra-high-speed asynchronous motor, wherein the solid rotor body is integrally formed from magnetically conductive high-strength alloy steel.

[0012] The rotor guide bar fixing structure of this invention for ultra-high-speed asynchronous motors, because the fixing between the rotor guide bars and the rotor core no longer relies on the original expansion cage structure, but is ensured by interference fit in the height direction, can effectively guarantee that the rotor is firmly fixed at high speeds and overspeed conditions. This avoids deviations caused by inconsistent expansion cages during operator work and effectively solves the problem of high-strength alloy copper guide bars being unable to achieve effective tension due to the high surface hardness of the material, ensuring effective fixing of solid rotor guide bars. This is beneficial for subsequent overspeed and high-speed dynamic balancing of the high-speed motor rotor and vibration control during overall machine testing, improving the stability and reliability of ultra-high-speed motor operation. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the rotor bar structure in the prior art; Figure 2 This is a schematic diagram of the guide bar mounting groove in a rotor core in the prior art; Figure 3 This is a schematic diagram of the fit between the rotor bars and the rotor core in the prior art; Figure 4 for Figure 3 A magnified view of part B1 in the middle; Figure 5 Schematic diagram of rotor guide bar expansion cage; Figure 6 for Figure 5 A magnified view of part B2; Figure 7 for Figure 5 Sectional view along axis AA; Figure 8 This is a schematic diagram of the rotor guide bar fixing structure of the ultra-high speed asynchronous motor of the present invention; Figure 9 for Figure 8 A magnified view of part B3; Figure 10 This is a structural diagram of the rotor guide bar of the ultra-high speed asynchronous motor rotor guide bar fixing structure of the present invention; Figure 11 This is a schematic diagram of the guide bar mounting groove of the ultra-high speed asynchronous motor rotor guide bar fixing structure of the present invention. Detailed Implementation

[0014] To enable those skilled in the art to better understand the technical solution of the present invention, its specific embodiments are described in detail below with reference to the accompanying drawings: Please see Figure 8 , Figure 9 , Figure 10 and Figure 11 The preferred embodiment of the present invention is a rotor guide bar fixing structure for an ultra-high speed asynchronous motor, comprising a solid rotor body 2 and rotor guide bars 3.

[0015] The solid rotor body 2 is integrally formed from magnetic high-strength alloy steel. Multiple guide bar mounting slots 21 are provided on the outer periphery of the solid rotor body 2. A rotor guide bar 3 is inserted and fixed in each guide bar mounting slot 21. The rotor guide bar 3 has an outwardly protruding arc-shaped protrusion 31 in the middle. The rotor guide bar 3 is made of high-strength alloy copper material.

[0016] The shape of the guide bar mounting groove 21 matches the shape of the rotor guide bar 3, and satisfies the following mating relationship: In the width direction, the width dimension B of the rotor guide bar 3 and the width dimension B1 of the arc-shaped protrusion are both smaller than the corresponding width dimensions B′ and B1′ of the guide bar mounting groove 21, and a clearance fit is formed between the rotor guide bar 3 and the guide bar mounting groove 21 in the width direction. In the height direction, the height dimension H1 between the top of the arc-shaped protrusion 31 of the rotor guide bar 3 and the bottom surface of the rotor guide bar 3 is greater than the corresponding height dimension H1′ of the guide bar mounting groove, forming an interference fit; the height dimension H of the rotor guide bar 3 is equal to the height dimension H′ of the guide bar mounting groove.

[0017] The tolerance range for width dimensions B, B1, B′, and B1′ is -0.15 to 0 mm, and the tolerance range for height dimensions H1 and H1′ is 0.06 mm to 0.08 mm.

[0018] At least three non-collinear contact positioning surfaces are formed between the rotor guide bar 3 and the corresponding guide bar mounting groove 21. The three contact positioning surfaces constrain the radial, circumferential and axial degrees of freedom of the rotor guide bar to achieve complete positioning. The three contact positioning surfaces include: two contact positioning surfaces 41 located on the two inclined surfaces on the upper part of the arc-shaped protrusion 31 of the rotor guide bar 3; and one contact positioning surface 42 located on the bottom surface of the rotor guide bar 3.

[0019] The interference fit in the height direction is achieved through a heat fitting process: after heating and heat preservation of the solid rotor body 2, the rotor guide bar 3 at room temperature is inserted into the guide bar mounting groove 21; after the solid rotor body 2 cools down, the two sides of the upper part of the arc-shaped protrusion 31 of the rotor guide bar 3 are in close contact with the corresponding guide bar mounting groove 21, and the bottom surface of the rotor guide bar 3 is in close contact with the bottom surface of the guide bar mounting groove 21, thus fixing the rotor guide bar 3 in the guide bar mounting groove 21.

[0020] Please see Figure 10In this embodiment, the arc-shaped protrusion 31 consists of an upper inclined section, a middle arc-shaped section, and a lower inclined section. The inclination angle α of the upper inclined section is 45°, the radius R of the middle arc-shaped section is 5.5mm, the arc β is 90°, and the arc tolerance is -0.1° to +0.1°. The inclination angle of the two inclined surfaces on the lower part can also be 45°. The radius of the arc-shaped section corresponding to the guide bar mounting groove 21 and the arc-shaped protrusion is 5.0mm.

[0021] In this embodiment, the two corners of the bottom surface of the rotor guide bar 3 are rounded with a radius of 1.5mm. The two corners of the bottom end of the guide bar mounting groove 21 are rounded with a radius of 1.0mm.

[0022] The rotor guide bar fixing structure of the ultra-high speed asynchronous motor of the present invention has the following parameters: the gap between the rotor guide bar 3 and the guide bar mounting groove 21 in the width direction, and the interference fit between the rotor guide bar 3 and the guide bar mounting groove 21 in the height direction, are determined according to the rated speed and overspeed conditions of the motor. For example, the lower limit of the interference fit is satisfied that the deformation caused by centrifugal force will not cause the interference fit to fail under the highest overspeed conditions of the motor; the upper limit of the interference fit is satisfied that the heating temperature of the solid rotor body 2 and the pressing stress of the rotor guide bar 3 during the heat-fitting installation process will not cause the material to yield or the groove shape to undergo plastic deformation.

[0023] In summary, the rotor guide bar fixing structure of the ultra-high-speed asynchronous motor of the present invention, because the fixing between the rotor guide bar and the rotor core no longer relies on the original expansion cage structure, but is ensured by interference fit in the height direction, can effectively guarantee the rotor is firmly fixed at high speeds and overspeed conditions. This avoids deviations caused by inconsistent expansion cages during operator operation and effectively solves the problem of high-strength alloy copper guide bars being unable to achieve effective tension due to the high surface hardness of the material, ensuring the effective fixing of solid rotor guide bars. This is beneficial for subsequent overspeed and high-speed dynamic balancing of the high-speed motor rotor and vibration control during overall machine testing, improving the stability and reliability of the ultra-high-speed motor operation.

[0024] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A rotor guide bar fixing structure for an ultra-high-speed asynchronous motor, characterized in that, Includes a solid rotor body and rotor bars, wherein: The outer periphery of the solid rotor body is provided with multiple guide bar mounting slots; Each guide bar mounting slot is fitted with and fixed with one of the rotor guide bars, and the middle of the rotor guide bar has an outwardly protruding arc-shaped protrusion; The shape of the guide bar mounting groove matches the shape of the rotor guide bar, and satisfies the following fit relationship: In the width direction, the width dimension of the rotor guide bar is smaller than the corresponding width dimension of the guide bar mounting groove, forming a clearance fit; In the height direction, the height dimension between the top of the arc-shaped protrusion of the rotor guide bar and the bottom surface of the rotor guide bar is greater than the corresponding height dimension of the guide bar mounting groove, forming an interference fit; At least three non-collinear contact positioning surfaces are formed between the rotor guide bar and the corresponding guide bar mounting groove. The three contact positioning surfaces constrain the radial, circumferential and axial degrees of freedom of the rotor guide bar to achieve complete positioning.

2. A rotor bar fixation structure for an ultrahigh-speed asynchronous motor according to claim 1, characterized in that The three contact positioning surfaces include: Two contact positioning surfaces located on the two inclined surfaces on the upper part of the arc-shaped protrusion of the rotor guide bar; and a contact positioning surface located on the bottom surface of the rotor guide bar.

3. A rotor bar fixing structure for an ultrahigh-speed asynchronous motor according to claim 1, characterized in that The interference fit is achieved through a heat-shrinking process: after heating and keeping the solid rotor body at room temperature, the rotor guide bar at room temperature is inserted into the guide bar mounting groove; after the solid rotor body cools down, the interference fit is formed in the height direction by thermal expansion and contraction.

4. A rotor bar fixation structure for an ultrahigh-speed asynchronous motor according to claim 1, characterized in that The two corners of the bottom surface of the rotor guide bar are rounded, and the two corners of the bottom end of the guide bar mounting groove are rounded.

5. A rotor bar fixation structure for an ultrahigh-speed asynchronous motor according to claim 1, characterized in that The rotor bars are made of high-strength alloy copper.

6. The rotor guide bar fixing structure for an ultra-high-speed asynchronous motor according to claim 1, characterized in that, The solid rotor body is integrally machined from magnetically conductive high-strength alloy steel.

Images