Long-service-life rotor assembly of hollow cup brush motor

Abstract

The utility model discloses a rotor assembly of a hollow cup brush motor with long service life, which comprises a rotating shaft, a rotor frame, a commutator, a circuit board and a capacitor, and is characterized in that the rotor frame and the rotating shaft are fixed together; the commutator is provided with an insulator and N commutator segments; n grooves are circumferentially distributed in the end face, close to the circuit board, of the rotor frame, and M capacitor bonding pads and N commutator segment bonding pads are circumferentially distributed on the face, close to the rotor frame, of the circuit board; the N capacitors and the N commutator segment bonding pads are alternately arranged; two capacitor bonding pads are arranged between any two adjacent commutator segment bonding pads, and each capacitor bonding pad is welded with one pin of a capacitor; for any adjacent capacitor bonding pad and commutator segment bonding pad, there is a distance therebetween and the capacitor bonding pad and commutator segment bonding pad are connected through a wire. According to the utility model, the circuit board is arranged on the rotor frame and the capacitor is arranged on the circuit board, so that electric sparks generated on the commutator can be absorbed through the capacitor, thereby prolonging the service life of the commutator.

Description

Technical Field

[0001] The utility model belongs to the field of motors, and more specifically, relates to a rotor assembly of a brush-commutated cup motor with high service life. Background Art

[0002] The conventional structure of the rotor of a brush-commutated cup motor includes a wire cup, a rotor frame, a rotor shaft and a commutator. The rotor frame is fixedly sleeved on the rotor shaft, the commutator is installed on the rotor frame, the wire cup sleeves the rotor frame, and a circle of wire ends circumferentially distributed on the wire cup are welded to the commutator.

[0003] When the brush-commutated cup motor works, the brushes contact and rub against the commutator segments. Since there are gaps between the commutator segments, electric sparks will be generated during commutation. The long-term electric sparks will cause faults such as the brushes being burned out, the commutator segments being burned through, and the motor not working. Moreover, the electric sparks are generated inside the motor and are not easily detected. It is often found that the brushes are burned out and the commutator segments are burned through only after disassembling the motor for inspection when a fault occurs in the motor. At present, the conventional treatment method is to clean and replace the brushes or the commutator, but this requires disassembling the motor and is relatively troublesome to handle.

[0004] In addition, the commutator and the rotor frame on the brush-commutated cup motor are generally of a split structure. Before welding the commutator to the wire cup, the commutator needs to be installed on the rotor frame first. There are multiple grooves on the rotor frame surrounding a circle, and there are multiple side bosses on the commutator surrounding a circle. Each side boss of the commutator is respectively pressed into a groove, and the commutator and the rotor frame can be assembled. At present, manual alignment is used, and then a manual pressing tool is used to press the bosses of the commutator into the grooves of the rotor frame. The assembly of the commutator and the rotor frame is time-consuming and laborious, and the production efficiency is low. Summary of the Utility Model

[0005] In view of the above defects or improvement requirements of the prior art, the present utility model provides a rotor assembly of a brush-commutated cup motor with high service life. By installing a circuit board on the rotor frame and installing a capacitor on the circuit board, the capacitor can absorb the electric sparks generated on the commutator, thereby improving the service life of the commutator.

[0006] To achieve the above object, according to the present utility model, there is provided a rotor assembly of a brush-commutated cup motor with high service life, characterized in that it includes a rotating shaft, a rotor frame, a commutator, a circuit board and a capacitor, wherein:

[0007] The rotor frame is fixedly connected to the rotating shaft by an injection molding method;

[0008] The commutator has an insulator and N commutator segments, and these commutator segments are circumferentially and uniformly arranged on the outer surface of the insulator. The insulator is fixedly sleeved on the rotating shaft, and one end of each commutator segment is embedded in the rotor frame while the other end is exposed outside the rotor frame;

[0009] The circuit board is fixedly installed at one end of the rotor frame close to the commutator;

[0010] N grooves are circumferentially distributed on the end face of the rotor frame close to the circuit board. M capacitor pads and N commutator segment pads are circumferentially distributed on the surface of the circuit board close to the rotor frame, where M:N = 2:1 and N≥2, and each groove houses one of the capacitors;

[0011] The N capacitors and the N commutator segment pads are alternately arranged;

[0012] For any two adjacent commutator segment pads, two capacitor pads are arranged between them, and each capacitor pad is respectively welded to one lead of the capacitor;

[0013] For any adjacent capacitor pad and commutator segment pad, there is a spacing between them and they are connected by a wire;

[0014] Each commutator segment pad is respectively welded to a commutator segment on the commutator.

[0015] Preferably, the capacitance of each capacitor is as follows:

[0016] C = 1000P / (2πfV 2 );

[0017] Where:

[0018] C is the capacitance of the capacitor, in microfarads;

[0019] P is the power of the motor, in watts;

[0020] f is the frequency of the power supply, in hertz;

[0021] V is the rated voltage of the motor, in volts;

[0022] π is the ratio of the circumference of a circle to its diameter.

[0023] Preferably, the rotor frame and the insulator are integrally formed by an injection molding process, and the integrally formed rotor frame and insulator fix the rotating shaft and the commutator segments together.

[0024] Preferably, a dovetail groove is provided on the rotating shaft to allow the plastic of the rotor frame to enter the dovetail groove during injection molding.

[0025] Preferably, knurling is provided on the rotating shaft so that the plastic of the rotor frame can enter the knurling during injection molding.

[0026] Preferably, the dovetail grooves and knurling are evenly arranged on the rotating shaft in the circumferential direction.

[0027] Preferably, the rotor frame is cylindrical as a whole, and the circuit board is annular.

[0028] Preferably, the circuit board is a flexible circuit board.

[0029] Preferably, for any adjacent capacitor pads and commutator segment pads, green oil is disposed between them and covers the conductive wire.

[0030] Preferably, each of the commutator segments is L-shaped.

[0031] In general, the above technical solutions conceived by the utility model can achieve the following beneficial effects compared with the prior art:

[0032] 1) The utility model discloses a rotor assembly of a hollow cup brush motor with a long service life. A circuit board with a capacitor welded thereon is mounted on a rotor frame. The capacitor can absorb sparks generated when the commutator is commutated, thereby extending the service life of the commutator of the motor.

[0033] 2) The utility model provides a rotor assembly of a hollow cup brush motor with a long service life. The capacitance of the capacitor is appropriately selected to fully absorb the electric sparks generated by the commutator.

[0034] 3) The utility model discloses a rotor assembly of a hollow cup brushless motor with a long lifespan, in which the rotor frame and the insulator are injection molded and fixedly connected with the rotating shaft and the commutator segments as a whole. The rotor frame and the commutator do not need to be assembled later, which improves the production efficiency and avoids the errors caused by the assembly of the two. It only needs to ensure the concentricity of the rotor frame, the commutator segments and the rotating shaft during the injection molding process, which is easy to control and improve the concentricity accuracy, can reduce the vibration of the rotor assembly during operation, and reduce the generation of electric sparks.

[0035] 4) The utility model is a rotor assembly of a high-life hollow cup brush motor, in which the rotor frame and the insulator are injection molded and fixedly connected to the rotating shaft and the commutator segments as a whole, and no extra installation space needs to be reserved. It is easy to design and manufacture, and can effectively reduce the size of the commutator head, making the motor more compact, and improving the power density of the motor of the same volume, so that the motor can be used in places with smaller spaces.

[0036] 5) The utility model provides a rotor assembly of a hollow cup brush motor with a long service life, and the knurling or dovetail groove on the rotating shaft can make the connection between the rotor frame, the commutator and the rotating shaft more secure, and improve the shedding force and torque between the rotor frame, the commutator and the rotating shaft.

[0037] 6) The rotor assembly of a long-life coreless brushed motor of the present utility model uses a flexible circuit board for the circuit board, which is thinner than a PCB board. Therefore, space can be saved, making the overall motor more compact and improving the power density of the motor of the same volume. The motor can be used in places with smaller space. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic structural diagram of the present utility model after removing the circuit board;

[0039] Figure 2 is a schematic diagram of the capacitor of the present utility model welded on the capacitor pad of the circuit board;

[0040] Figure 3 is a schematic diagram of the rotating shaft of the present utility model;

[0041] Figure 4 is a cross-sectional view of the present utility model;

[0042] Figure 5 is a schematic diagram of the rotating shaft passing through the circuit board of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] In order to make the objectives, technical solutions and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model. In addition, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0044] Refer to Figures 1 to 5 , a rotor assembly of a long-life coreless brushed motor, comprising a rotating shaft 1, a rotor frame 3, a commutator 2, a circuit board 5 and a capacitor 4, wherein:

[0045] The rotor frame 3 is fixed to the rotating shaft 1 by injection molding. The rotor frame 3 is preferably cylindrical as a whole for easy rotation. The rotor frame 3 is made of plastic. One function of the rotor frame 3 is to fix the commutator 2 and the rotating shaft 1, and another function is to fixedly support the wire cup.

[0046] The commutator 2 has an insulator 21 and N commutator segments 22, and these commutator segments 22 are circumferentially and uniformly arranged on the outer surface of the insulator 21. The insulator 21 is fixedly sleeved on the rotating shaft 1. One end of each commutator segment 22 is embedded in the rotor frame 3 and the other end is exposed outside the rotor frame 3. Each commutator segment 22 is preferably L-shaped. Both the rotor frame 3 and the insulator 21 of the commutator 2 are fixedly sleeved on the rotating shaft 1. The rotor frame 3 and the insulator 21 of the commutator 2 can be separated or integrally formed. In the present utility model, it is preferred that the rotor frame 3 and the insulator 21 are integrally formed by an injection molding process. The integrally formed rotor frame 3 and insulator 21 fix the rotating shaft 1 and the commutator segments 22 together, which is equivalent to integrally forming the rotating shaft 1, the rotor frame 3 and the commutator 2 into a whole. After integral forming, the commutator 2 and the rotor frame 3 do not need to be assembled subsequently, avoiding the errors caused by assembly, being easy to ensure the concentricity of the rotor frame 3, the commutator 2 and the rotating shaft 1, reducing the runout during the operation of the rotor assembly, and reducing the generation of electric sparks.

[0047] The circuit board 5 is fixedly installed at one end of the rotor frame 3 close to the commutator 2. The circuit board 5 preferably adopts a flexible circuit board, which is convenient for installation and can save space, making the whole motor more compact, and the motor can be used in places with smaller space. Adapted to the shape of the cylindrical rotor frame 3, the circuit board 5 is annular.

[0048] N grooves 31 are circumferentially distributed on the end face of the rotor frame 3 close to the circuit board 5. M capacitor pads 51 and N commutator segment pads 52 are circumferentially distributed on the side of the circuit board 5 close to the rotor frame 3, where M:N = 2:1 and N≥2. Each groove 31 accommodates one of the capacitors 4;

[0049] The N capacitors 4 and the N commutator segment pads 52 are arranged alternately;

[0050] For any two adjacent commutator segment pads 52, two capacitor pads 51 are arranged between them, and each capacitor pad 51 is respectively welded to one lead of the capacitor 4;

[0051] For any adjacent capacitor pad 51 and commutator segment pad 52, there is a spacing between them and they are connected by a wire (also called a copper film trace), and the wire can realize the conduction between the capacitor pad 51 and the commutator segment pad 52.

[0052] In addition, for any adjacent capacitor pad 51 and commutator segment pad 52, solder mask 53 is provided between them and the solder mask 53 covers the wire. The solder mask 53 serves as a protective layer to protect the wire.

[0053] By the connection and conduction of the capacitor pads 51 and the commutator segment pads 52, all the capacitors 4 can be connected in series.

[0054] Each of the commutator segment pads 52 is welded to a corresponding commutator segment 22 on the commutator 2 respectively.

[0055] The part of the commutator segment 22 embedded in the rotor holder 3 is directly welded to the commutator segment pad 52. After the commutator segment pad 52 is welded to the commutator segment 22, the current on the commutator segment 22 enters the capacitor 4 on the circuit board 5 through the commutator segment pad 52. The capacitor 4 can absorb the electric sparks generated when the commutator segment 22 of the commutator 2 operates, effectively preventing the commutator segment 22 from being ablated, thereby extending the service life of the commutator 2.

[0056] During installation, the pins of the capacitor 4 are first welded to the capacitor pads 51 on the circuit board 5, then the circuit board 5 is installed on the rotor holder 3, and then the commutator segment 22 is welded to the commutator segment pad 52.

[0057] Furthermore, the capacitance of each capacitor 4 is as follows:

[0058] C = 1000P / (2πfV 2 );

[0059] Where:

[0060] C represents the capacitance of the capacitor 4, with the unit of microfarad;

[0061] P is the power of the motor, with the unit of watt;

[0062] f is the frequency of the power supply, with the unit of hertz;

[0063] V is the rated voltage of the motor, with the unit of volt;

[0064] π is the ratio of a circle's circumference to its diameter, preferably taking the value of 3.14.

[0065] Calculating the capacitance of the capacitor 4 in this way enables it to fully absorb the electric sparks on the commutator 2.

[0066] Furthermore, a dovetail groove 12 is provided on the rotating shaft 1 to allow the plastic of the rotor holder 3 to enter the dovetail groove 12 during injection molding, making the connection between the rotor holder 3 and the rotating shaft 1 more secure. The groove wall of the dovetail groove 12 is trapezoidal, which can hook the plastic in the dovetail groove 12, thereby preventing the rotor holder 3 and the insulator 21 from loosening when the rotating shaft 1 rotates.

[0067] Furthermore, knurling 11 is also provided on the rotating shaft 1 to allow the plastic of the rotor holder 3 to enter the knurling 11 during injection molding, thereby making the connection between the rotor holder 3 and the insulator 21 and the rotating shaft 1 more secure.

[0068] The number of the dovetail grooves 12 is preferably not less than 3, and the knurling 11 is preferably one circle, and they are circumferentially and uniformly arranged on the rotating shaft 1.

[0069] In the utility model, a circuit board 5 and a capacitor 4 are arranged on a rotor frame 3, the capacitor 4 is relied on to absorb electric sparks, and the rotor frame 3, a commutator 2 and the rotating shaft 1 are integrally formed, so as to improve the concentricity of the rotor frame 3 and the commutator 2 with the rotating shaft 1, thereby reducing the runout during the operation of the rotor assembly and reducing the generation of electric sparks. All these measures can prolong the service life of the motor.

[0070] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present utility model and is not used to limit the present utility model. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

Claims

1. A rotor assembly of a coreless brushless motor with a long service life, characterized in that: It includes a rotating shaft, a rotor frame, a commutator, a circuit board and a capacitor, wherein: The rotor frame is fixed together with the rotating shaft by injection molding; The commutator comprises an insulator and N commutator segments, and the commutator segments are evenly arranged on the outer surface of the insulator in the circumferential direction, the insulator is fixedly mounted on the rotating shaft, one end of each commutator segment is embedded in the rotor frame and the other end is exposed from the rotor frame; The circuit board is fixedly mounted on one end of the rotor frame close to the commutator; The rotor frame has N grooves distributed circumferentially on the end surface close to the circuit board, and the circuit board has M capacitor pads and N commutator pads distributed circumferentially on one side close to the rotor frame, wherein M:N=2:1 and N≥2, and each groove contains one capacitor; The N capacitors and the N commutator segment pads are arranged alternately; For any two adjacent commutator segment pads, two capacitor pads are arranged between them, and each capacitor pad is respectively welded with a pin of the capacitor; For any adjacent capacitor pads and commutator segment pads, there is a spacing between them and they are connected by wires; Each of the commutator segment welding pads is respectively welded to a commutator segment on the commutator.

2. The rotor assembly of a coreless brushless motor with a long service life according to claim 1, characterized in that: The capacitance of each of the capacitors is as follows: C=1000P / (2πfV 2 ); in: C is the capacitance of the capacitor, in microfarads; P is the power of the motor in watts; f is the frequency of the power supply in Hertz; V is the rated voltage of the motor in volts; π is the ratio of a circle to its circumference.

3. The rotor assembly of a coreless brushless motor with a long service life according to claim 1, characterized in that: The rotor frame and the insulator are integrally formed by an injection molding process, and the integrally formed rotor frame and the insulator fix the rotating shaft and the commutator segments together.

4. The rotor assembly of a coreless brushless motor with a long service life according to claim 3, characterized in that: The rotating shaft is provided with a dovetail groove so that the plastic of the rotor frame can enter the dovetail groove during injection molding.

5. The rotor assembly of a coreless brushless motor with a long service life according to claim 4, characterized in that: The rotating shaft is provided with knurling so that the plastic of the rotor frame can enter the knurling during injection molding.

6. The rotor assembly of a coreless brushless motor with a long service life according to claim 5, characterized in that: The dovetail grooves and knurling are evenly arranged on the rotating shaft in the circumferential direction.

7. The rotor assembly of a coreless brushless motor with a long service life according to claim 1, characterized in that: The rotor frame is cylindrical as a whole, and the circuit board is annular.

8. The rotor assembly of a coreless brushless motor with a long service life according to claim 1, characterized in that: The circuit board is a flexible circuit board.

9. The rotor assembly of a coreless brushless motor with a long service life according to claim 1, characterized in that: For any adjacent capacitor pads and commutator segment pads, green oil is arranged between them and covers the conductive wires.

10. The rotor assembly of a coreless brushless motor with a long service life according to claim 1, characterized in that: Each of the commutator segments is L-shaped.

Images