Inner rotor motor

Abstract

The present application discloses an internal rotor motor including a stator assembly and a rotor assembly rotatably disposed within the stator assembly. The stator assembly includes a stator housing, magnets disposed on the inner wall of the stator housing, and brushes. The magnets form a magnetic field stationary with respect to the stator housing. The rotor assembly includes a core, a rotating shaft inserted into the core, and coils wound around the core. A slip ring is sleeved on the rotating shaft, the slip ring is electrically connected to the coils, one end of the brush abuts against the slip ring, and the other end is configured to electrically connect to an external AC power source. The internal rotor motor described in the present application can maintain a cost equivalent to that of existing brushed motors while achieving performance comparable to that of existing brushless motors. In addition, the internal rotor motor has a generally simple structure, is easy to manufacture, and has a broad market outlook.

Description

Technical Field

[0001] This application relates to the field of motor technology, and particularly to an internal rotor motor.

Background Art

[0002] A motor consists of a stator and a rotor that rotate relative to each other. Based on the positional relationship between the stator and the rotor, motors can be divided into two main types: internal rotor motors and external rotor motors. Internal rotor motors have characteristics such as high rotational speed and are widely used in daily life and industrial production.

[0003] Internal rotor motors can be divided into two types: brushed motors and brushless motors based on the method of current rectification. Brushed motors use mechanical rectification and have characteristics such as quick start, timely braking, and simple control circuits. However, electric sparks are likely to occur easily due to the friction between the brush and the commutator, which not only affects the life of the brush but also causes a series of problems including NVH (noise, vibration, harshness) and EMC (electromagnetic compatibility). Brushless motors utilize electronic rectification and bring advantages such as high efficiency, low noise, and long life. However, the size of the internal rotor is limited, and in order to obtain the same output torque as a brushed motor of the same size, it is necessary to use a strong magnetic material such as neodymium-iron-boron magnets, which significantly increases the cost of the motor.

Summary of the Invention

[0004] In view of this, an internal rotor motor that takes into account motor performance and cost is provided.

[0005] An internal rotor motor comprising a stator assembly and a rotor assembly rotatably disposed within the stator assembly, wherein the stator assembly comprises a stator housing, magnets disposed on the inner wall of the stator housing, and brushes, the magnets form a magnetic field stationary with respect to the stator assembly, the rotor assembly comprises a core, a rotating shaft inserted into the core, and a coil wound around the core, a slip ring is sleeve-connected to the rotating shaft, the slip ring is electrically connected to the coil, one end of the brush abuts against the slip ring, and the other end of the brush is configured to electrically connect to an external AC power source.

[0006] In some embodiments, the magnetic field axis formed when power is supplied to the coil is stationary relative to the magnetic field axis formed by the magnets.

[0007] In some embodiments, the slip ring comprises at least two mutually insulated conductive rings, the brush comprises at least two mutually insulated carbon brushes, and each carbon brush abuts against one of the conductive rings.

[0008] In some embodiments, the coil is a polyphase coil, the number of conductive rings is greater than or equal to the number of phases of the polyphase coil, and each phase coil is electrically connected to one of the conductive rings.

[0009] In some embodiments, the coil is a single-phase coil, the number of conductive rings and the number of carbon brushes are two, and the two conductive rings are connected to the head end and the tail end of the coil respectively.

[0010] In some embodiments, at least two conductive rings are spaced along the axial direction of the rotating shaft, or at least two conductive rings are spaced along the radial direction of the rotating shaft.

[0011] In some embodiments, the magnet is an electromagnet or a permanent magnet and is arranged at intervals along the circumferential direction of the stator housing.

[0012] In some embodiments, the brush is arranged on the end cap, the end cap covers the axial side portion of the stator housing, and a bearing for supporting the rotation of the rotor assembly is provided at the center of the end cap.

[0013] In some embodiments, a cover cap is provided on the other axial side portion of the stator housing, and another bearing for supporting the rotation of the rotor assembly is provided at the center of the cover cap.

[0014] In some embodiments, the connection terminal protrudes from the outer portion of the end cap and is electrically connected to the other end of the brush, and the connection terminal is configured to connect to an external AC power supply.

[0015] Compared with the prior art, the internal rotor motor of the present application is characterized by having a magnet positioned on the stator assembly outside the motor, and a low-cost and weak magnetic material can be used, which can effectively reduce the cost of the motor. Further, the slip ring and the brush are only electrically connected and do not have a commutation function, thereby avoiding the electric spark generated by mechanical commutation and improving the problems related to NVH and EMC. As a result, the internal rotor motor of the present application can achieve performance comparable to that of existing brushless motors while maintaining a cost equivalent to that of existing brushed motors. Further, the internal rotor motor has a simple overall structure, is easy to manufacture, and has a broad market prospect.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0017] To facilitate the understanding of the present application, a more comprehensive description is provided below with reference to the related accompanying drawings. The drawings exemplarily show one or more embodiments of the present application and make the understanding of the technical solutions disclosed in the present application more accurate and thorough. However, it should be understood that the present application can be implemented in various forms and is not limited to the embodiments described below.

[0018] In the accompanying drawings of the present application, the same or similar reference numerals correspond to the same or similar components. In the present application, it should be understood that terms such as "upper", "lower", "left" and "right" are used to indicate the positional relationship or direction relationship based on the orientation or position shown in the drawings. These terms are for the convenience of the description of the present application only and are for simplifying the description, and do not indicate or imply that the device or element mentioned must have a specific orientation or must be configured and operated in a specific orientation. Therefore, the terms used to describe the positional relationship in the drawings are for the purpose of description only and should not be understood as limiting the present patent. Those skilled in the art can understand the specific meanings of the above-mentioned terms based on the specific situation.

[0019] The present application provides an internal rotor motor, and FIGS. 1 to 3 show specific embodiments of the present application. The internal rotor motor includes a stator assembly 10 and a rotor assembly 30 rotatably disposed within the stator assembly 10.

[0020] Referring to FIGS. 3 and 4, the stator assembly 10 includes a stator housing 12 and magnets 14 attached to the inner wall surface of the stator housing 12. The magnets 14 are arranged at uniform intervals along the circumferential direction of the stator housing 12, and adjacent magnets 14 have opposite polarities. Specifically, in two adjacent magnets 14, if one has a radially inner end portion that is an N pole and a radially outer end portion that is an S pole, the other will have a radially inner end portion that is an S pole and a radially outer end portion that is an N pole. The stator assembly 10 forms N poles and S poles alternately in the circumferential direction, forming a stator magnetic field that is stationary with respect to the stator housing 12. The magnets 14 are arranged on the outer side of the motor and are preferably permanent magnets made of a weakly magnetic material such as ferrite. The ferrite material is mainly composed of iron oxide and other iron group or rare earth oxides, and provides advantages such as low eddy current loss and low cost.

[0021] It should be understood that without considering factors such as cost, the magnets 14 can also be permanent magnets made of a strong magnetic material such as neodymium-iron-boron, or the magnets 14 can also be electromagnets that generate a stable magnetic field when energized.

[0022] Referring to both FIGS. 2 and 3, the rotor assembly 30 includes a core 32, a rotating shaft 34 inserted into the core 32, and a coil 36 wound around the core 32. The core 32 can be made of stacked silicon steel sheets and includes a yoke portion sleeved to the shaft 34 and teeth extending radially outward from the yoke portion. The rotating shaft 34 is fixedly inserted into the yoke portion of the core 32, and both ends extend outside the core 32 to transmit the output to the outside. The coil 36 is wound around each of the teeth, and adjacent teeth are arranged at intervals in the circumferential direction to form a winding slot 37 for winding the coil 36. The coil 36 preferably uses three-phase coils (U, V, W), and each phase coil 36 can be composed of a plurality of coils connected in parallel or in series. In FIG. 5, different phase coils 36 are shown in different in-line types. For example, the dashed line represents the U-phase coil, the dotted line represents the V-phase coil, and the solid line represents the W-phase coil.

[0023] As shown in FIG. 2, the rotor assembly 30 also includes a slip ring 38 sleeved on the shaft 34. The stator assembly 10 further includes a brush 16 corresponding to the slip ring 38, and the brush 16 abuts against the slip ring 38. When the internal rotor motor rotates, the slip ring 38 rotates coaxially with the shaft 34. During the rotation process, the brush 16 continuously abuts against the slip ring 38 and cooperates with the slip ring 38 to enable an external power source to supply power to the coil 36.

[0024] The slip ring 38 includes at least two conductive rings 381 that are electrically insulated from each other. The brush 16 includes at least two carbon brushes 161 that are electrically insulated from each other, and each carbon brush 161 abuts against one of the conductive rings 381. As shown in FIGS. 2 to 4, the at least two conductive rings 381 can be arranged at intervals in the axial direction along the axial direction of the shaft 34. The at least two carbon brushes 161 create a height difference in the axial direction of the motor. The inner end of each carbon brush 161 abuts against one of the radially outer surfaces of the conductive ring 381 and has conductivity. The at least two carbon brushes 161 can be arranged axially aligned or alternately arranged axially. The diameters of the at least two conductive rings 381 may be the same or different. In some embodiments, the at least two conductive rings 381 can also be arranged along the radial direction of the shaft 34. For example, they can be at least two concentric rings arranged at intervals in the radial direction. Correspondingly, the brush 16 can be axially aligned with the slip ring 38. For example, it is arranged on the axial side of the slip ring 38 away from or facing the core 32. Each carbon brush 161 abuts against one end face of the conductive ring 381 to achieve electrical conduction. The at least two carbon brushes 161 are arranged side by side in the radial direction or are arranged offset in the radial direction.

[0025] It should also be noted that the slip ring 38 can also be attached at any suitable position on the shaft 34. By arranging the brush 16 and the slip ring 38 on the same side of the motor, the electrical connection to the external power supply is facilitated. In some embodiments, the conductive ring 381 of the slip ring 38 can also be arranged on both sides of the shaft 34, and accordingly, each carbon brush 161 of the brush 16 can also be arranged on both sides of the motor. Regarding the arrangement and position of at least two conductive rings 381 and at least two carbon brushes 161, the present application does not impose specific restrictions. As long as each conductive ring 381 is insulated from each other, each carbon brush 161 is insulated from each other, and each carbon brush 161 is in contact with the conductive ring 381 to achieve conductivity, all are within the protection scope of the present application.

[0026] In an embodiment of the present application, the magnetic field axis formed when power is supplied to the coil 36 is stationary relative to the magnetic field axis formed by the magnet 14. Preferably, a commutation circuit is also connected between the coil 36 and the external power supply. The commutation circuit controls the phase of the current flowing through the coil 36 to relatively stationary the magnetic field axes of the rotor and the stator. The commutation circuit can be built into the control circuit board inside the motor, and the commutation circuit can also be an external control circuit of the motor.

[0027] The coil 36 is a polyphase coil or a single-phase coil. Correspondingly, the external power supply is an AC power supply such as a polyphase or single-phase AC power supply. When the coil 36 is a polyphase coil, the number of conductive rings 381 is equal to or greater than the number of phases of the polyphase coil, and each phase coil 36 is electrically connected to one of the conductive rings 381. Therefore, each phase coil 36 can be connected to the external power supply via one conductive ring 381 and the carbon brush 161 that abuts against the conductive ring 381. The number of conductive rings 381 is preferably equal to the number of phases of the polyphase coil. When the coil 36 is a single-phase coil, both the number of conductive rings 381 and the number of carbon brushes 161 are two. The two conductive rings 381 are respectively connected to the head end portion and the trailing end portion of the single-phase coil. Therefore, both ends of the single-phase coil can be connected to the external power supply via one conductive ring 381 and the carbon brush 161 that abuts against the conductive ring 381.

[0028] In some embodiments, the brush 16 is fixedly disposed inside an end cap 18 that covers one axial side portion of the stator housing 12. At least two connection terminals 181 protrude from the outer side portion of the end cap 18 and are electrically connected to the outer ends of at least two brushes 161. The at least two connection terminals 181 are used to connect to an external AC power supply. Preferably, the other axial side portion of the stator housing 12 is covered by a cover cap 19, and the centers of the cover cap 19 and the end cap 18 respectively form bearing seats for mounting the bearings 39. The two end portions of the shaft 34 are respectively inserted into the bearings 39, and the bearings 39 support the shaft 34 and enable the rotor assembly 30 to rotate smoothly.

[0029] As shown in FIGS. 2 to 4 below, in order to explain the internal rotor motor of the present application, a three-phase coil will be taken as an example for explanation. The slip ring 38 adopted has three conductive rings 381, and the brush 16 has three carbon brushes 161. When the internal rotor motor starts, a three-phase alternating current is conducted to the three-phase coil 36 of the rotor assembly 30 by the cooperation of the three carbon brushes 161 and the three collector rings 381. The alternating current can be in the form of a sine wave, a rectangular wave, or the like. The current of each phase coil 36 generates a rotating magnetic field by generating a 120-degree phase difference, and continuously rotates the rotor assembly 30 with respect to the stator assembly 10. During the rotation of the rotor assembly 30, the carbon brush 161 maintains conductivity with the conductive ring 381 and functions as an electrical connection part. It should be understood that the coil 36 of the rotor assembly 30 can be configured with any number of phases, such as four phases, five phases, etc. In this case, the number of the conductive rings 381 and the carbon brushes 161 is adjusted according to the number of phases of the coil 36, and each conductive ring 381 connects one-phase coil 36 to an external power source. In addition, in the embodiment of the present application, although a three-phase coil is taken as an example for explanation, the present invention is not limited to this configuration.

[0030] The internal rotor motor of the present application introduces an alternating current power source to the coil 36 by using the slip ring 38 and the brush 16. The rotor assembly 30 is arranged at the center of the motor and is provided with an energized coil 36. The stator assembly 10 is arranged on the outer part of the motor, includes a magnet 14, and the overall structure is the same as that of a conventional brushed DC motor. Since the magnet 14 is arranged near the outer part of the motor, the size can be increased, and the material used can be a weakly magnetic material. Compared with the ferromagnetic material generally required for the rotor of an existing brushless motor, the cost of the motor can be effectively reduced. The coil 36 is wound around the core 32 of the rotor assembly 30, and the fly winding method generally used in existing brushed motors can be utilized. Compared with the needle winding and segment winding methods used in existing brushless motors, this method is simpler and faster, so the motor cost can be further reduced.

[0031] In this application, the slip ring 38 and the brush 16 cooperate to conduct current without the need for current rectification, effectively avoiding the generation of electric sparks compared to existing brushed motors. This leads to an improvement in the lifespan of the brush 16 and electromagnetic compatibility (EMC). Furthermore, since the bounce that occurs when the brush 16 separates from the commutator in an existing brushed motor can also be avoided, problems such as noise, vibration, and harshness (NVH) caused by this effect can also be reduced. Additionally, the invention of this application introduces an electronic commutator to replace the mechanical commutator, effectively reducing torque pulsation and further lowering NVH. In summary, the internal rotor motor of this application can achieve performance comparable to that of existing brushless motors while maintaining the same cost as existing brushed motors, effectively balancing the performance and cost of the motor, and is particularly suitable for small motors such as 48V motors used in electric vehicles.

[0032] Note that this application is not limited to the above embodiments. Based on the creative spirit of this application, those skilled in the art can make other modifications, and all such modifications made in accordance with the creative spirit of this application should be included within the scope of protection claimed in this application.

Description of Reference Numerals

[0033] 10 Stator Assembly 12 Stator Housing 14 Magnet 19 Core 36 Coil 38 Slip Ring 161 Carbon Brush 381 Conductive Ring

Claims

1. An internal rotor motor comprising a stator assembly and a rotor assembly rotatably disposed within the stator assembly, wherein the stator assembly comprises a stator housing, a magnet disposed on the inner wall of the stator housing, and a brush, the magnet forms a magnetic field stationary with respect to the stator assembly, the rotor assembly comprises a core, a rotating shaft inserted into the core, and a coil wound around the core, a slip ring is sleeve-connected to the rotating shaft, the slip ring is electrically connected to the coil, one end of the brush abuts against the slip ring, and the other end of the brush is configured to electrically connect to an external AC power source. An internal rotor motor characterized by the above.

2. The magnetic field axis formed when power is supplied to the coil is stationary relative to the magnetic field axis formed by the magnet. The internal rotor motor according to claim 1, characterized by the above.

3. The slip ring comprises at least two mutually insulated conductive rings, the brush comprises at least two mutually insulated carbon brushes, and each carbon brush abuts against one of the conductive rings. The internal rotor motor according to claim 1, characterized by the above.

4. The coil is a polyphase coil, the number of the conductive rings is not less than the number of phases of the polyphase coil, and each phase coil is electrically connected to one of the conductive rings. The internal rotor motor according to claim 3, characterized by the above.

5. The coil is a single-phase coil, the number of the conductive rings and the number of the carbon brushes are two, and the two conductive rings are respectively connected to the head end portion and the tail end portion of the coil. The internal rotor motor according to claim 3, characterized by the above.

6. The at least two conductive rings are arranged at intervals along the axial direction of the rotating shaft, or the at least two conductive rings are arranged at intervals along the radial direction of the rotating shaft. The internal rotor motor according to claim 3, characterized by the above.

7. The magnet is an electromagnet or a permanent magnet and is arranged at intervals along the circumferential direction of the stator housing. The internal rotor motor according to any one of claims 1 to 6, characterized in that.

8. The brushed motor is arranged on the end cap. The end cap covers the axial side portion of the stator housing. A bearing for supporting the rotation of the rotor assembly is provided at the center of the end cap. The internal rotor motor according to any one of claims 1 to 6, characterized in that.

9. A cover cap is provided on the other axial side surface of the stator housing. Another bearing for supporting the rotation of the rotor assembly is provided at the center of the cover cap. The internal rotor motor according to claim 8, characterized in that.

10. The connection terminal protrudes from the outer portion of the end cap and is electrically connected to the other end of the brush. The connection terminal is configured to connect the external AC power supply. The internal rotor motor according to claim 8, characterized in that.

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