CN110277865A - Hollow cup brush direct current motor and robot - Google Patents

Abstract

The invention belongs to the technical field of motors, and aims to provide a coreless brushed DC motor and a robot, including a pull tube sleeved on the motor shaft, an inner magnetic ring sleeved on the pull tube, and an inner magnetic ring movably sleeved on the inner magnetic ring. The coreless winding assembly, wherein the outer magnetic ring is fixedly connected to the casing, and the motor shaft drives the load. In the present invention, by setting the inner magnetic ring as an annular magnetic ring with more even-numbered poles, it is ensured that the N poles and S poles of the inner and outer magnetic rings correspond to each other, and a sinusoidal magnetization method is adopted to effectively reduce the magnetic flux leakage of the motor and improve the motor performance. The magnetic density waveform of the internal air gap enables the internal magnetic ring to exert the maximum magnetic performance per unit volume, thereby increasing the output torque and output efficiency of the motor, reducing the torque fluctuation of the motor, and reducing the cost of the motor.

Description

A hollow cup brushed DC motor and robot

technical field

The invention belongs to the technical field of motors, and more specifically relates to a coreless brushed DC motor and a robot.

Background technique

The coreless motor belongs to the DC permanent magnet servo and control motor. Because it adopts the ironless rotor, it completely eliminates the power loss caused by the eddy current formed by the iron core in the traditional motor. Therefore, it has outstanding energy-saving characteristics and is sensitive and convenient. Control characteristics and stable running characteristics. Generally, coreless motors are divided into two types: brushed and brushless. Taking the type of brush as an example, the existing coreless brushed DC motor is equipped with a magnetically conductive thin stainless steel drawing tube inside the permanent magnet, and a bearing is installed in the drawing tube, and the rotating shaft of the motor passes through the bearing, and the drawing tube There is an air gap between the shaft and the motor shaft.

Among them, when the magnetic field circuit formed by the permanent magnet passes through the pull tube and the motor shaft, there are likely to be problems such as large leakage magnetic field of the motor as a whole, uneven magnetic density distribution of the air gap, and difficulty in realizing sinusoidal magnetization; at the same time, due to the pull tube and the motor shaft If the air gap is too large, the magnetic circuit will be saturated, which will easily cause a certain amount of magnetic flux leakage in the local permanent magnet magnetic circuit, making it difficult for the magnetic flux density of the air gap of the motor to reach the optimum state, that is, the magnetic density of the air gap will decrease. In addition, the excessive use of NdFeB permanent magnets not only leads to material waste, but also greatly increases the cost of the motor, and there are also problems such as large motor torque fluctuations.

Contents of the invention

The object of the present invention is to provide a coreless brushed DC motor, which is used to solve the problems of large magnetic flux leakage, uneven and reduced magnetic density distribution of the air gap, high motor cost and low torque in the existing coreless brushed DC motor. Volatile technical issues.

In order to solve the above technical problems, the technical solution adopted by the present invention is to provide a coreless brushed DC motor, which comprises:

The casing is a hollow structure with openings;

a rear cover assembly, covering the opening of the casing; and,

The motor shaft, one end is connected to the inner side wall of the rear cover assembly, and the other end extends to the outside of the casing;

In the casing, the coreless brushed DC motor also includes:

The first bearing is sleeved on the motor shaft at a side away from the rear cover assembly;

The second bearing is sleeved on the motor shaft and connected to the rear cover assembly;

A pull tube is sleeved on the motor shaft, one end is connected to the first bearing, and the other end is connected to the second bearing;

The inner magnetic ring is sleeved on the pull tube; and,

The hollow cup winding assembly is movably sleeved on the inner magnetic ring;

Wherein, the inner magnetic ring is an annular structure formed by 2P magnetic poles, and P is a positive integer greater than 1.

In one embodiment, the coreless brushed DC motor also includes an outer magnetic ring;

The outer magnetic ring is an annular structure formed by 2P magnetic poles, P is a positive integer greater than 1, and the outer magnetic ring corresponds to the N pole and the S pole of the inner magnetic ring;

The outer magnetic ring is sleeved on the inner magnetic ring and fixedly connected to the casing;

The coreless winding assembly is located between the outer magnetic ring and the inner magnetic ring, and can perform circular motion around the motor shaft.

In one embodiment, the N poles and S poles in the inner magnetic ring are adjacently arranged and evenly distributed around the center of the inner magnetic ring; the N poles and S poles in the outer magnetic ring are adjacently arranged, and evenly distributed around the center of the outer magnetic ring.

In one embodiment, one end of the drawing tube is connected to the outer ring of the first bearing, and the other end is connected to the outer ring of the second bearing.

In one embodiment, the centerlines of the pull tube, the inner magnetic ring, the coreless winding assembly and the outer magnetic ring are located on the same straight line as the central axis of the motor shaft.

In one embodiment, two ends of the pull tube, the inner magnetic ring and the outer magnetic ring are correspondingly aligned.

In one embodiment, the inner surface of the inner magnetic ring is adapted to the outer surface of the pull tube.

In one embodiment, markings to facilitate magnetization are provided on the outer peripheral walls of the inner magnetic ring and the outer magnetic ring.

In one embodiment, the rear cover assembly includes a cover covering the opening, a brush provided on the inner wall of the cover, and pins extending to the outside of the cover.

The object of the present invention is also to provide a robot, which includes the above-mentioned coreless brushed DC motor.

The coreless brushed DC motor and the robot provided by the present invention, by setting the inner magnetic ring to a magnetic ring structure formed by 2P magnetic poles, P is a positive integer greater than 1, that is, the inner magnetic ring is changed to more even-numbered poles On the basis of changing the structure of the magnetic ring, the magnetic circuit of the motor can be effectively reduced, and the magnetic density waveform of the air gap inside the motor can be improved without major changes to the existing coreless brushed DC motor. , increase the air-gap magnetic density of the motor, so that the inner magnetic ring can exert the maximum magnetic performance per unit volume, thereby increasing the output torque and output efficiency of the motor, reducing the torque fluctuation of the motor, and improving the overall performance of the motor. Reduce the size of the motor.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings that need to be used in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only for the present invention. For some embodiments, those skilled in the art can also obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of the appearance and structure of a hollow cup brushed DC motor in an embodiment of the present invention;

Fig. 2 is a three-dimensional exploded schematic diagram of the coreless brushed DC motor in Fig. 1;

Fig. 3 is a side view of the coreless brushed DC motor in Fig. 1;

Fig. 4 is a cross-sectional view of the A-A section of the hollow cup brushed DC motor in Fig. 3;

Fig. 5 is a three-dimensional schematic diagram of the hollow cup brushed DC motor in Fig. 1 after removing the shell, the rear cover assembly and each bearing;

Fig. 6 is a schematic diagram of a three-dimensional assembly structure between the inner magnetic ring and the outer magnetic ring of the hollow cup brushed DC motor in Fig. 4;

Fig. 7 is a side view of Fig. 6;

Fig. 8 is a distribution diagram of magnetic force lines of a 2-pole coreless motor in an example;

Fig. 9 is a distribution diagram of magnetic force lines of a 4-pole coreless brushed DC motor in an embodiment of the present invention;

Fig. 10 is the waveform diagram of the air-gap flux density when the 2-pole coreless motor is no-loaded in the example;

Fig. 11 is an air-gap flux density waveform diagram when a 4-pole coreless brushed DC motor is no-loaded in an embodiment of the present invention;

Fig. 12 is an FFT waveform diagram of the air-gap magnetic density when the 2-pole coreless motor is unloaded in the example;

Fig. 13 is an FFT waveform diagram of the air-gap magnetic density when the 4-pole hollow cup brushed DC motor is no-loaded in the embodiment of the present invention;

Fig. 14 is a waveform diagram of back electromotive force when a 2-pole coreless motor is unloaded in the example;

Fig. 15 is a waveform diagram of back electromotive force of a 4-pole coreless brushed DC motor in an embodiment of the present invention when it is no-loaded.

Wherein, the label in the accompanying drawing is as follows:

100-chassis, 110-cavity, 120-opening, 130-bottom of the shell;

200-back cover assembly, 210-cover body, 220-pin;

300-motor shaft, 400-first bearing, 500-second bearing;

600-pull tube, 610-groove, 620-through hole;

700-inner magnetic ring, 710-first N pole, 720-first S pole, 800-outer magnetic ring, 810-second N pole, 820-second S pole, 900-coreless cup winding assembly.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with specific drawings and specific embodiments. Wherein, the same or similar symbols in the drawings of the specific embodiments of the present invention indicate the same or similar elements, or elements with the same or similar functions. It should be understood that the specific embodiments described below are intended to explain the present invention, not to limit the present invention.

It should be noted that when an element is referred to as being “fixed on” or “mounted on” or “provided on” or “connected to” another element, it may be directly or indirectly located on the other element. For example, when an element is referred to as being "connected to" another element, it can be directly or indirectly connected to the other element. The terms "length", "width", "top", "bottom", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", The orientations or positions indicated by "inside" and "outside" are based on the orientations or positions shown in the drawings, and are for convenience of description only, and should not be construed as limitations on the technical solution.

In addition, the terms "first" and "second" are only for convenience of description, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of technical features. "Plurality" means two or more, unless otherwise clearly and specifically defined. In a word, those of ordinary skill in the art can understand the specific meanings of the above terms according to specific situations.

The implementation of a hollow cup brushed DC motor provided by the present invention will be described in detail below with reference to FIGS. 1 to 15 .

It should be noted that the coreless brushed DC motor can be used in robots, and can also be used in other suitable products, which is not limited here.

As shown in FIGS. 1 to 4 , the coreless brushed DC motor includes a casing 100 , a rear cover assembly 200 and a motor shaft 300 . Wherein, as shown in FIG. 2 and FIG. 4 , the casing 100 is generally a hollow structure with an opening 120 opened therein. Specifically, the casing 100 may be composed of multiple casings, or integrally formed. As shown in FIG. 4 , the casing 100 is provided with a cavity 110 and an opening 120 communicating with the cavity 110 , and the rear cover assembly 200 is covered on the opening 120 of the casing 100 , so that the gap between the casing 100 and the rear cover assembly 200 A closed accommodating space can be formed, which is beneficial to reduce magnetic leakage and protect the coreless brushed DC motor.

In the present invention, on the side opposite to the opening 120 of the casing 100 , the bottom 130 of the casing 100 defines a connection hole (not shown). As shown in FIG. 4, one end of the motor shaft 300 is connected to the inner side wall of the rear cover assembly 200, and the other end of the motor shaft 300 extends out of the casing 100, specifically, the other end of the motor shaft 300 (ie, the load end) The casing 100 passes through the connection hole and protrudes from the connection hole.

In the present invention, as shown in FIG. 4 , in the casing 100, the coreless brushed DC motor also includes a first bearing 400, a second bearing 500, a pull tube 600, an inner magnetic ring 700, an outer magnetic ring 800 and Coreless winding assembly 900 . Wherein, the first bearing 400 is sleeved on the motor shaft 300 at a side away from the rear cover assembly 200 , and the second bearing 500 is sleeved on the motor shaft 300 and connected to the rear cover assembly 200 . As shown in FIG. 4 , the pull tube 600 is sleeved on the motor shaft 300 , and one end of the pull tube 600 is connected to the first bearing 400 , and the other end is connected to the second bearing 500 . Wherein, the pull tube 600 is fixedly bonded together through the interference fit of the motor shaft 300 or by glue, so as to ensure that the pull tube 600 is connected to the motor shaft 300 and can rotate together with the motor shaft 300 . Thus, when the pull tube 600 rotates, the torque can be transmitted to the motor shaft 300 through the first bearing 400 and the second bearing 500 , thereby driving the load connected to the load end of the motor shaft 300 to rotate.

In the present invention, as shown in Figure 4, the inner magnetic ring 700 is sleeved on the pull tube 600; correspondingly, the outer magnetic ring 800 is sleeved on the inner magnetic ring 700 and fixedly connected to the casing 100; the coreless winding The component 900 is between the inner magnetic ring 700 and the outer magnetic ring 800, and is movably sleeved on the inner magnetic ring 700; it can be understood that, as shown in FIG. The inner and outer magnetic rings 700 and 800 are fixed, and the coreless winding assembly 900 can move in a circle around the central axis of the motor shaft 300 .

Wherein, in the present invention, as shown in FIG. 6 and FIG. 7 , the inner magnetic ring 700 and the outer magnetic ring 800 are annular structures formed by 2P magnetic poles, and P is a positive integer greater than 1. That is to say, the inner magnetic ring 700 may be a ring structure formed by an even number of magnetic poles such as 4 magnetic poles or 6 magnetic poles. Similarly, the outer magnetic ring 800 may also be a ring structure formed by an even number of magnetic poles such as 4 magnetic poles or 6 magnetic poles. In addition, the N poles and S poles of the inner magnetic ring 700 and the outer magnetic ring 800 correspond to each other. In this way, the inner magnetic ring 700 and the outer magnetic ring 800 can fully exert the maximum magnetic performance per unit volume.

It can be understood that the inner magnetic ring 700 includes at least two N poles and at least two S poles, and correspondingly, the outer magnetic ring 800 includes at least two N poles and at least two S poles. Usually, in order to ensure that the magnetic field lines are evenly distributed as far as possible, the N poles and S poles in the inner magnetic ring 700 are arranged adjacent to each other, and the N poles and S poles in the inner magnetic ring 700 are evenly distributed around the center of the inner magnetic ring 700. Similarly, the outer magnetic ring 700 N poles and S poles in the ring 800 are arranged adjacently, and the N poles and S poles in the outer magnetic ring 800 are evenly distributed around the center of the outer magnetic ring 800 .

Specifically as shown in FIG. 7, taking four magnetic poles as an example, the inner magnetic ring 700 includes two first N poles 710 and two first S poles 720, wherein the first N poles 710 and the first S poles 720 are adjacent setting; similarly, the outer magnetic ring 800 includes two second N poles 810 and two second S poles 820, wherein the second N poles 810 and the second S poles 820 are arranged adjacently, obviously, in the inner magnetic ring 700 The first N pole 710 of the outer magnetic ring 800 corresponds to the second S pole 820 in the radial direction, and the angle between the starting end and the ending end of the first N pole 710 and the second S pole 820 is equal to is 90 degrees. Similarly, the first S pole 720 in the inner magnetic ring 700 corresponds to the second N pole 810 in the outer magnetic ring 800 in the radial direction, and the starting end and the end of the first S pole 720 and the second N pole 810 The angle between the ends is 90 degrees.

It should be noted that both the inner magnetic ring 700 and the outer magnetic ring 800 are made of NdFeB magnet material. In addition, because of the multi-pole structure, the motor is more likely to magnetize the magnetic poles in the inner magnetic ring 700 and the outer magnetic ring 800 through sinusoidal magnetization, so that the air gap flux waveform of the motor can be improved and the torque fluctuation of the motor can be reduced , improve the torque capacity of the motor, specifically, the torque coefficient and the coefficient of the back electromotive force of the motor can be improved, so the operating effect of the motor is improved and the temperature rise is reduced. In the case of ensuring the performance of the motor, the amount of permanent magnets (such as the magnetic material in the inner magnetic ring 700 and the outer magnetic ring 800 ) can be reduced, thereby reducing the cost of the motor.

In one embodiment, as shown in FIG. 4 , in order to reduce the overall volume of the motor, ensure a more compact structure of the motor, and ensure smooth transmission of torque, in the cavity 110 of the casing 100, one end of the pull tube 600 The outer ring of the first bearing 400 is connected, and the other end of the pull tube 600 is connected with the outer ring of the second bearing 500 . Specifically, as shown in Figure 4 and Figure 5, in the axial direction of the pull tube 600, grooves 610 are respectively opened at both ends of the pull tube 600, and the pull tube 600 is provided with a through hole 620 communicating with the two grooves 610 . Wherein, the motor shaft 300 passes through the through hole 620 . The first bearing 400 passes through the motor shaft 300, the outer ring of one end (such as the right end) abuts against the groove bottom of the groove 610 at the corresponding end (such as the left end) of the pull tube 600, and the other end (that is, the side away from the rear cover assembly 200 end, such as the left end) with a gap between the inner side wall of the casing 100 (specifically, the bottom 130 of the casing). Correspondingly, the second bearing 500 passes through the motor shaft 300, the outer ring of one end (such as the left end) abuts against the bottom of the groove 610 of the corresponding end (such as the right end) of the pull tube 600, and the other end (such as the right end) is fixedly connected on the inner wall of the rear cover assembly 200 .

In one embodiment, as shown in Figure 4, in order to ensure that the generated torque can be smoothly transmitted to the motor shaft 300, improve the torque performance of the motor, and reduce the production cost of the motor, the pull tube 600, the inner magnetic ring 700, the hollow The central axis of the cup winding assembly 900 and the outer magnetic ring 800 and the central axis of the motor shaft 300 are located on the same straight line. That is, the pull tube 600 , the inner magnetic ring 700 , the coreless winding assembly 900 , the outer magnetic ring 800 and the motor shaft 300 are arranged coaxially. Understandably, the coreless winding assembly 900 rotates coaxially with the motor shaft 300 .

In one embodiment, as shown in FIG. 4 , in order to reduce the volume of the motor and ensure that the structure of the motor is more compact, thereby reducing production costs, the two ends of the pull tube 600 , the inner magnetic ring 700 and the outer magnetic ring 800 are aligned correspondingly. . Specifically, the left end of the pull tube 600, the left end of the inner magnetic ring 700, and the left end of the outer magnetic ring 800 are aligned, and the right end of the pull tube 600, the right end of the inner magnetic ring 700, and the right end of the outer magnetic ring 800 are aligned. It can be understood that the axial length of the pull tube 600 , the axial length of the inner magnetic ring 700 and the axial length of the outer magnetic ring 800 are the same. Of course, in practice, the axial lengths of the three can be slightly different. For example, the axial length of the pull tube 600 may be slightly greater than or slightly smaller than the axial length of the inner magnetic ring 700 .

In one embodiment, as shown in FIG. 4 , similarly, in order to further reduce the volume of the motor and reduce the production cost of the motor, the two ends of the coreless winding assembly 900 are respectively aligned with the two ends of the inner magnetic ring 700 . For example, the left end of the coreless winding assembly 900 is aligned with the left end of the inner magnetic ring 700 . Understandably, the axial length of the coreless winding assembly 900 is also equal to the axial length of the inner magnetic ring 700 .

In one embodiment, as shown in Figure 4, in order to ensure that the flux density of the motor is evenly distributed, increase the flux density of the motor air gap, and improve the torque performance of the motor, the inner surface of the inner magnetic ring 700 is closely connected to the outer surface of the pull tube 600 adaptation. It can be understood that the shape and size of the inner surface of the inner magnetic ring 700 are respectively adapted to the shape and size of the outer surface of the pull tube 600 . Therefore, there is no gap between the inner magnetic ring 700 and the pull tube 600 .

In one embodiment, as shown in FIG. 4 , in order to facilitate sinusoidal magnetization of each magnetic pole in the inner magnetic ring 700 and the outer magnetic ring 800, the outer peripheral wall of the inner magnetic ring 700 is provided with marks for easy magnetization (Fig. not shown), correspondingly, the outer peripheral wall of the outer magnetic ring 800 is provided with markings (not shown) to facilitate magnetization. It should be noted that the marks on the inner magnetic ring 700 may be the same as those on the outer magnetic ring 800 or may be different, and the two may be marking lines or other suitable markings.

In one embodiment, as shown in FIGS. 2 and 4 , the rear cover assembly 200 includes a cover body 210 , a brush (not shown in the figure) and pins 220 . Wherein, the cover 210 is disposed on the opening 120 of the housing 100 ; the brushes are disposed on the inner wall of the cover 210 ; and the pins 220 extend to the outside of the cover 210 . Specifically in this embodiment, an interference fit is used between the cover body 210 and the casing 100 to ensure a firm connection between the cover body 210 and the casing 100, and to make the cavity 110 of the casing 100 an airtight space; the rear cover assembly 200 includes a pair of brushes and a pair of pins 220 , wherein the brushes are in one-to-one correspondence with the pins 220 and are electrically connected. Understandably, the brushes are electrically connected to the external DC power supply through corresponding pins 220 .

It should be noted that, in one embodiment, the coreless winding assembly 900 includes a winding coil (not shown), a commutator (not shown) and a bracket (not shown). Wherein, the winding coil is arranged coaxially with the motor shaft 300 , the commutator is arranged on one end of the motor shaft 300 close to the rear shell assembly, and the bracket is arranged in the rear cover assembly 200 . In addition, there are gaps between the winding coil and the inner magnetic ring 700 and the outer magnetic ring 800 . It can be understood that the electric energy of the DC power supply enters the winding coil through the brushes and the commutator, and the winding coil rotates in the magnetic field generated by the current, so that the moving winding coil and the inner magnetic ring 700 and the outer magnetic ring 800 form a main The magnetic fields interact to generate an electromagnetic torque, and finally drive the load to move through the rotation of the motor shaft 300 .

It should be noted that, compared with the coreless motor in the example (being a 2-pole single permanent magnet structure), the hollow cup brushed DC motor of the present invention (taking the double magnetic ring structure of 4 poles as an example) is analyzed from the data. , roughly has the following characteristics:

(1) As shown in Fig. 8 and Fig. 9, the distribution of the magnetic field lines of the 4-pole double magnetic ring DC motor of the present invention is more uniform, and correspondingly, the magnetic flux leakage will be relatively less;

(2) As shown in Fig. 10 and Fig. 11, the air-gap flux density waveform of the 4-pole double magnetic ring DC motor of the present invention is closer to a sinusoidal curve; in addition, as shown in Fig. 12 and Fig. 13, the 4-pole of the present invention When the double-magnetic ring DC motor is under no load, the amplitude of the air-gap flux density FFT waveform increases. Specifically, the amplitude in the example is 0.633, and the amplitude in the present invention is 0.90, so it can be increased by 1.43 times. Of course, in practice, the ratio of the amplitude may vary depending on other settings, but the general trend is that the amplitude is increased;

(3) As shown in Fig. 14 and Fig. 15, when the 4-pole double-magnetic ring DC motor of the present invention is under no load, the coefficient of the counter electromotive force in the waveform diagram of the counter electromotive force increases. Specifically, the coefficient in the example is 20, and the amplitude in the present invention is 31.1, so it can be increased by 1.55 times. Of course, in practice, the ratio of the coefficient of the counter electromotive force may vary according to different settings according to actual needs, but the general trend is that the ratio of the coefficient is greater than 1, that is, the coefficient is increased. It can be understood that the sinusoidal degree of the back EMF waveform in the present invention is good, and the harmonic content will be significantly reduced.

Generally speaking, compared with the single permanent magnet hollow cup brushed DC motor structure with 2 poles in the example, the coreless brushed DC motor in the present invention does not require major changes, mainly by changing the structure of the magnetic ring. The inner magnetic ring 700 is set to a magnetic ring with more even-numbered poles from 2 poles. In addition, an outer magnetic ring 800 is added, and the outer magnetic ring 800 is also set to a magnetic ring with more even-numbered poles. The magnetization method is changed to sinusoidal magnetization, thus, through the multi-pole structure of the inner magnetic ring 700 and the outer magnetic ring 800, the magnetic circuit of the motor can be effectively reduced, the magnetic density waveform of the air gap inside the motor can be improved, and the air gap of the motor can be increased. Gap magnetic density, so that the inner magnetic ring 700 and the outer magnetic ring 800 can respectively exert the maximum magnetic performance per unit volume, thereby increasing the output torque and output efficiency of the motor, reducing the torque fluctuation of the motor, and improving the overall performance of the motor. performance, thereby reducing the size of the motor and reducing the cost of the motor.

The present invention also provides a robot, which includes the above hollow cup brushed DC motor. Among them, the robot uses the coreless brushed DC motor, which has more stable response, better torque performance and lower cost.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Various modifications and variations of the present invention will occur to those skilled in the art. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of the claims of the present invention.

Claims (10)

1. a kind of drag cup brushed DC motor, comprising:

Casing, for the hollow structure for offering opening；

Rear case component is covered on the opening of the casing；And

Machine shaft, one end are connected on the inner sidewall of the rear case component, and the other end extends to outside the casing；

It is characterized in that, in the casing, the drag cup brushed DC motor further include:

First bearing is sheathed on the machine shaft in the side far from the rear case component；

Second bearing is sheathed on the machine shaft, and is connected on the rear case component；

Trombone slide is socketed on the machine shaft, and one end connects the first bearing, and the other end connects the second bearing；

Internal magnetic ring is sheathed on the trombone slide；And

Drag cup winding assembly is movably set in the internal magnetic ring；

Wherein, the internal magnetic ring is the ring structure that 2P magnetic pole is formed, and P is the positive integer greater than 1.

2. drag cup brushed DC motor according to claim 1, which is characterized in that the drag cup brushed DC motor It further include outer magnetic ring；

The outer magnetic ring is the ring structure that 2P magnetic pole is formed, and P is positive integer greater than 1, and the outer magnetic ring and described interior The pole N of magnet ring and S are extremely corresponding；

The outer magnetic ring is sheathed on the internal magnetic ring, and is fixedly connected on the casing；

The drag cup winding assembly can do circle around the machine shaft between the outer magnetic ring and the internal magnetic ring Zhou Yundong.

3. drag cup brushed DC motor according to claim 2, which is characterized in that the pole N and the pole S in the internal magnetic ring It is disposed adjacent, and is uniformly distributed around the center of the internal magnetic ring；The pole N and the pole S in the outer magnetic ring are disposed adjacent, and are surrounded The center of the outer magnetic ring is uniformly distributed.

4. drag cup brushed DC motor according to claim 2, which is characterized in that described in one end connection of the trombone slide The outer ring of first bearing, the other end connect the outer ring of the second bearing.

5. drag cup brushed DC motor according to claim 2, which is characterized in that the trombone slide, the internal magnetic ring, institute The central axis for stating the center line and the machine shaft of drag cup winding assembly and the outer magnetic ring is located along the same line.

6. drag cup brushed DC motor according to claim 2, which is characterized in that the trombone slide, the internal magnetic ring and The both ends correspondence of the outer magnetic ring aligns.

7. drag cup brushed DC motor according to claim 1, which is characterized in that the inner surface of the internal magnetic ring and institute State the outer surface adaptation of trombone slide.

8. drag cup brushed DC motor according to claim 2, which is characterized in that the internal magnetic ring and the outer magnetic ring Periphery wall on be provided with convenient for the label that magnetizes.

9. according to the described in any item drag cup brushed DC motors of claim 2 to 8, which is characterized in that the rear case component Including the lid being covered in the opening, the brush being set on the lid inner sidewall and extend on the outside of the lid Pin.

10. a kind of robot, which is characterized in that including drag cup brushed DC electricity according to any one of claims 1 to 9 Machine.