Tubular cage bar miniature intermediate frequency asynchronous motor with adjustable starting torque

Abstract

The invention discloses a tubular cage bar miniature intermediate frequency asynchronous motor with an adjustable starting torque, which comprises a casing with an open right end and a main shaft coaxially and rotatably arranged in the casing, an end cover is arranged at the right end of the casing, a housing is arranged on the right side of the end cover, a stator is arranged on the inner circle of the casing, a rotor is arranged on the outer circle of the main shaft, and an annular air gap is formed between the outer circle of the rotor and the inner circle of the stator. The rotor comprises a left end ring, a lamination assembly and a right end ring which are sequentially arranged from left to right, the inner circle of the lamination assembly is fixedly connected with the main shaft, and a plurality of hollow cage bars parallel to the main shaft are arranged among the left end ring, the lamination assembly and the right end ring and are evenly arranged in the circumferential direction of the main shaft. According to the invention, an existing solid cage bar is mainly improved into a hollow cage bar, the material and the wall thickness of the cage bar are changed, and different torque characteristics can be generated for motors with the same power to adapt to different working conditions, so that large starting torque and higher power factors can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of asynchronous motors, and in particular relates to a micro medium-frequency asynchronous motor with a tubular cage bar and adjustable starting torque. Background Art

[0002] Micro asynchronous motors generally use 400HZ medium frequency power supply, the speed can reach 20000RPM, and they often use cylindrical cage bar design, usually with a diameter of less than 6mm. The outer diameter of the rotor is less than 30mm. It is difficult to use cast aluminum structure for this kind of micro motor. T2 copper bars are often used as cage bars, and the end rings are made of the same material as the cage bars. After welding, the rotor is processed to the appropriate size by lathe and grinder. Then the rotor is completed after checking the dynamic balance.

[0003] Medium frequency micro asynchronous motors are high-speed motors. The characteristics of high-speed motors are high speed and low torque. Therefore, in extreme cases, such as low temperature, grease viscosity, etc., the starting torque is relatively large. When a high-speed motor starts, it is a high-frequency oscillating torque, which may cause starting difficulties. In order to increase the starting torque, it is often used to reduce the number of coil turns or replace the cage bars with high resistance materials. However, reducing the number of coil turns will greatly reduce the power factor of the motor. It is not easy to match the cage bar material with a suitable material. Therefore, it is urgent to improve the rotor structure of the existing high-speed motor. Summary of the invention

[0004] In order to solve the above technical problems existing in the prior art, the present invention provides a micro medium-frequency asynchronous motor with adjustable starting torque and tubular cage bars, which has a larger starting torque without reducing the power factor of the motor.

[0005] In order to solve the above technical problems, the present invention adopts the following technical scheme: a micro medium-frequency asynchronous motor with a tubular cage bar with adjustable starting torque, comprising a casing with an open right end and a main shaft coaxially rotating inside the casing, an end cover is provided at the right end of the casing, a cover is provided on the right side of the end cover, a stator is provided on the inner circle of the casing, a rotor is provided on the outer circle of the main shaft, an annular air gap exists between the outer circle of the rotor and the inner circle of the stator, the rotor comprises a left end ring, a lamination assembly and a right end ring arranged in sequence from left to right, the inner circle of the lamination assembly is fixedly connected to the main shaft, a plurality of hollow cage bars parallel to the main shaft are provided between the left end ring, the lamination assembly and the right end ring, and the hollow cage bars are evenly arranged along the circumferential direction of the main shaft.

[0006] The left end ring and the right end ring have the same structure and are symmetrical on the left and right. A number of left and right transparent through holes are evenly opened in the circumferential direction on the left end ring, the stacked assembly and the right end ring. The hollow cage bars are inserted in the through holes. The left and right ends of the hollow cage bars are flush with the left end face of the left end ring and the right end face of the right end ring respectively. The left half of the through hole of the left end ring and the right half of the through hole of the right end ring are both conical holes with the left side larger and the right side smaller. The outer circles of the left and right ends of the hollow cage bars are fixedly connected to the left and right end rings as a whole by welding in the conical holes.

[0007] A positioning shoulder is integrally provided on the left side of the main shaft, the inner circle of the left end ring is sleeved on the positioning shoulder and has a clearance match with the outer circle of the positioning shoulder; a sleeve is threadedly connected on the right side of the main shaft, the inner circle of the right end ring is sleeved on the sleeve and has a clearance match with the outer circle of the sleeve.

[0008] The left end of the main shaft extends out of the casing, and the left and right sides of the outer circle of the main shaft are rotatably connected with the casing and the end cover through a left bearing and a right bearing respectively.

[0009] The casing and the end cover are connected via first screws arranged radially, and the cover shell and the end cover are connected via second screws arranged radially.

[0010] A filter and a printed circuit board assembly are arranged in the cover, a sensor assembly and a retaining ring for limiting the axial position of the sensor assembly are coaxially mounted on the outer circle of the right end of the main shaft, the printed circuit board assembly is located between the left side of the filter and the right side of the sensor assembly, the printed circuit board assembly is connected to the filter through a first cable, the stator is connected to the filter through a second cable, the printed circuit board assembly is connected to a power cord, and a wiring port for inserting the power cord is opened on the cover.

[0011] The outside of the case is provided with heat dissipation ribs.

[0012] The present invention adopts the above technical solution, and adopts hollow cage bars (metal tubes). According to the working conditions required by users, copper tubes with different wall thicknesses or hollow cage bars of other materials are matched. The advantage is that the stator and rotor of the micro medium frequency asynchronous motor with the same power and speed remain unchanged. It only needs to provide metals of different materials as cage bar materials. Only by changing the wall thickness and material of the hollow cage bar, the mechanical characteristics of the motor can be changed to adapt to the needs of different working conditions. It can adapt to different starting torque conditions, and the power factor remains basically unchanged, which solves the problem of difficulty in starting with low temperature and load, and fully meets customer needs.

[0013] When installing the rotor, first install the lamination assembly on the hollow shaft from right to left, then install the shaft sleeve, and then install the left end ring to the outside of the positioning shoulder, and then install the right end ring to the outside of the shaft sleeve. The through holes on the left end ring, lamination assembly and right end ring are correspondingly transparent on the left and right, and then the hollow cage bar is inserted into the through holes, and finally the left and right ends of the hollow cage bar are welded to the left and right end rings respectively.

[0014] The end cover and the casing, as well as the end cover and the cover are connected by screws for easy installation and disassembly. The retaining ring is used to axially position the sensor assembly. The inner circle of the sensor assembly is connected to the outer circle of the main shaft through a flat key, which ensures that the sensor assembly can rotate with the main shaft. The sensor assembly transmits signals such as rotation speed to the printed circuit board assembly.

[0015] In summary, the present invention mainly improves the existing solid cage bars into hollow cage bars, and changes the cage bar material and wall thickness, which can produce different torque characteristics for motors of the same power and adapt to different working conditions, thereby achieving a large starting torque and a higher power factor. The present invention has the following economic benefits: The current electric drive field is moving towards the field of miniaturization and high speed, and the rated point is high speed and low torque. However, low torque often makes it difficult for the motor to start under certain working conditions. The present invention can solve this problem, and without changing other structures of the stator and rotor, it is conducive to reducing costs and mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the appearance of the present invention; Figure 2 It is a schematic diagram of the axial cross-sectional structure of the present invention; Figure 3 is a schematic diagram of the axial cross-sectional structure of the rotor; Figure 4 It is a schematic diagram of the planar structure of the left end ring and the right end ring; Figure 5 yes Figure 4 Middle CC section view; Figure 6 It is an axial cross-sectional view of the hollow cage bar. DETAILED DESCRIPTION

[0017] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0018] like Figure 1-Figure 6 As shown, the micro medium-frequency asynchronous motor with adjustable starting torque of the present invention comprises a casing 10 with an open right end and a main shaft 1 coaxially rotatably arranged inside the casing 10, an end cover 11 is arranged at the right end of the casing 10, a cover shell 12 is arranged on the right side of the end cover 11, a stator 13 is arranged on the inner circle of the casing 10, a rotor 14 is arranged on the outer circle of the main shaft 1, an annular air gap is provided with the outer circle of the rotor 14 and the inner circle of the stator 13, the rotor 14 comprises a left end ring 2, a lamination assembly 3 and a right end ring 4 which are arranged in sequence from left to right, the inner circle of the lamination assembly 3 is fixedly connected to the main shaft 1, a plurality of hollow cage bars 5 which are parallel to the main shaft 1 are arranged between the left end ring 2, the lamination assembly 3 and the right end ring 4, and the hollow cage bars 5 are evenly arranged along the circumferential direction of the main shaft 1.

[0019] The left end ring 2 and the right end ring 4 have the same structure and are symmetrical on the left and right. A number of left and right transparent through holes 6 are evenly opened in the circumferential direction on the left end ring 2, the stacked assembly 3 and the right end ring 4. The hollow cage bar 5 is inserted in the through hole 6. The left and right ends of the hollow cage bar 5 are flush with the left end face of the left end ring 2 and the right end face of the right end ring 4 respectively. The left half of the through hole 6 of the left end ring 2 and the right half of the through hole 6 of the right end ring 4 are both conical holes 7 with the left side larger and the right side smaller. The outer circles of the left and right ends of the hollow cage bar 5 are fixedly connected to the left end ring 2 and the right end ring 4 as a whole by welding in the conical hole 7.

[0020] A positioning shoulder 8 is integrally provided on the left side of the main shaft 1, the inner circle of the left end ring 2 is sleeved on the positioning shoulder 8 and has a clearance fit with the outer circle of the positioning shoulder 8, and a sleeve 9 is threadedly connected to the right side of the main shaft 1, the inner circle of the right end ring 4 is sleeved on the sleeve 9 and has a clearance fit with the outer circle of the sleeve 9.

[0021] The left end of the main shaft 1 extends out of the housing 10, and the left and right sides of the outer circle of the main shaft 1 are rotatably connected to the housing 10 and the end cover 11 through a left bearing 15 and a right bearing 16 respectively.

[0022] The housing 10 is connected to the end cover 11 via a radially arranged first screw 17 , and the cover shell 12 is connected to the end cover 11 via a radially arranged second screw 18 .

[0023] A filter 19 and a printed circuit board assembly 20 are provided in the housing 12. A sensor assembly 21 and a retaining ring 22 for limiting the axial position of the sensor assembly 21 are coaxially installed on the outer circle of the right end of the main shaft 1. The printed circuit board assembly 20 is located between the left side of the filter 19 and the right side of the sensor assembly 21. The printed circuit board assembly 20 is connected to the filter 19 through a first cable 23, and the stator 13 is connected to the filter 19 through a second cable 24. The printed circuit board assembly 20 is connected to a power cord 25, and a wiring port 26 for passing the power cord 25 is opened on the housing 12.

[0024] Heat dissipation ribs 27 are disposed outside the housing 10 .

[0025] The end cover 11 and the casing 10 as well as the end cover 11 and the cover shell 12 are connected by screws for easy installation and disassembly. The retaining ring 22 is used for axial positioning of the sensor assembly 21. The inner circle of the sensor assembly 21 is connected to the outer circle of the main shaft 1 by a flat key, so as to ensure that the sensor assembly 21 can rotate with the main shaft 1. The sensor assembly 21 transmits signals such as the rotation speed to the printed circuit board assembly 20.

[0026] The present invention adopts hollow cage bars 5 (metal tubes), and matches copper tubes or hollow cage bars 5 of different wall thicknesses or other materials according to the working conditions required by users. The advantage of this is that the stator 13 and the rotor of the micro medium frequency asynchronous motor at the same power and speed remain unchanged, and only metals of different materials need to be provided as cage bar materials. Only the wall thickness and material of the hollow cage bars 5 can be changed to change the mechanical characteristics of the motor, thereby adapting to the needs of different working conditions. It can adapt to different starting torque working conditions, the power factor remains basically unchanged, and the problem of difficulty in starting with load at low temperature is solved, which fully meets the needs of customers.

[0027] When installing the rotor, first install the lamination assembly 3 on the hollow shaft from right to left, then install the shaft sleeve 9, and then install the left end ring 2 to the outside of the positioning shoulder 8, and then install the right end ring 4 to the outside of the shaft sleeve 9. The through holes 6 on the left end ring 2, the lamination assembly 3 and the right end ring 4 are correspondingly transparent on the left and right sides, and then the hollow cage bar 5 is inserted into the through hole 6, and finally the left and right ends of the hollow cage bar 5 are respectively welded to the left end ring 2 and the right end ring 4.

[0028] Through testing, the present invention has designed a rotor 14 with an outer diameter of Φ69mm, which is installed on an asynchronous motor with a working speed of 11800rpm. It uses cage bars with Φ3.5mm and a wall thickness of 1mm. The starting torque is increased from 25mNm to 55mNm, and the power factor remains basically unchanged. The problem of difficulty in starting under low temperature load is solved, and customer needs are fully met.

[0029] The above embodiments illustrate the basic principles and features of the present invention, but the above only illustrates the preferred embodiments of the present invention and is not limited to the embodiments. Under the inspiration of this patent, a person skilled in the art can make many forms of deformation and improvement without departing from the scope of protection of the present invention and the claims, which are all within the protection scope of the present invention. Therefore, the patent and protection scope of the present invention shall be subject to the attached claims.

Claims

1. A micro medium-frequency asynchronous motor with a tubular cage bar and adjustable starting torque, comprising a casing with an open right end and a main shaft coaxially rotating inside the casing, an end cover is provided at the right end of the casing, a cover is provided on the right side of the end cover, a stator is provided on the inner circle of the casing, a rotor is provided on the outer circle of the main shaft, and an annular air gap is provided between the outer circle of the rotor and the inner circle of the stator, characterized in that: The rotor includes a left end ring, a lamination assembly and a right end ring which are arranged in sequence from left to right. The inner circle of the lamination assembly is fixedly connected to the main shaft. A number of hollow cage bars which are parallel to the main shaft are arranged between the left end ring, the lamination assembly and the right end ring. The hollow cage bars are evenly arranged along the circumferential direction of the main shaft.

2. The micro medium frequency asynchronous motor with adjustable starting torque of tubular cage bars according to claim 1 is characterized in that: The left end ring and the right end ring have the same structure and are symmetrical on the left and right. A number of left and right transparent through holes are evenly opened in the circumferential direction on the left end ring, the stacked assembly and the right end ring. The hollow cage bars are inserted in the through holes. The left and right ends of the hollow cage bars are flush with the left end face of the left end ring and the right end face of the right end ring respectively. The left half of the through hole of the left end ring and the right half of the through hole of the right end ring are both conical holes with the left side larger and the right side smaller. The outer circles of the left and right ends of the hollow cage bars are fixedly connected to the left and right end rings as a whole by welding in the conical holes.

3. The micro medium frequency asynchronous motor with adjustable starting torque according to claim 1 or 2, characterized in that: A positioning shoulder is integrally provided on the left side of the main shaft, the inner circle of the left end ring is sleeved on the positioning shoulder and has a clearance match with the outer circle of the positioning shoulder; a sleeve is threadedly connected on the right side of the main shaft, the inner circle of the right end ring is sleeved on the sleeve and has a clearance match with the outer circle of the sleeve.

4. The micro medium frequency asynchronous motor with adjustable starting torque according to any one of claims 1 to 3, characterized in that: The left end of the main shaft extends out of the casing, and the left and right sides of the outer circle of the main shaft are rotatably connected with the casing and the end cover through a left bearing and a right bearing respectively.

5. The micro medium frequency asynchronous motor with adjustable starting torque according to any one of claims 1 to 3, characterized in that: The casing and the end cover are connected via first screws arranged radially, and the cover shell and the end cover are connected via second screws arranged radially.

6. The micro medium frequency asynchronous motor with adjustable starting torque, tubular cage bars, according to claim 1 or 2, characterized in that: A filter and a printed circuit board assembly are arranged in the cover, a sensor assembly and a retaining ring for limiting the axial position of the sensor assembly are coaxially mounted on the outer circle of the right end of the main shaft, the printed circuit board assembly is located between the left side of the filter and the right side of the sensor assembly, the printed circuit board assembly is connected to the filter through a first cable, the stator is connected to the filter through a second cable, the printed circuit board assembly is connected to a power cord, and a wiring port for inserting the power cord is opened on the cover.

7. The micro medium frequency asynchronous motor with adjustable starting torque, tubular cage bars, according to claim 1 or 2, characterized in that: The outside of the case is provided with heat dissipation ribs.

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