Hub motor

Abstract

The utility model discloses a wheel hub motor, which comprises a wheel hub shell, a main shaft, a stator assembly, a rotor assembly, a magnetic encoder and a planetary reduction mechanism, and is characterized in that the magnetic encoder comprises a magnetic sensor connected with the stator assembly and a signal magnetic ring connected with the rotor assembly; the rotor assembly is connected with a zero-position magnetic ring coaxial with the signal magnetic ring, the zero-position magnetic ring comprises at least one pair of magnets which are sequentially distributed in the circumferential direction, and the magnetic poles of each pair of magnets are opposite; at least one sensing element is integrated on the end face of the magnetic sensor and used for sensing the magnetic field change of the zero-position magnetic ring so as to detect the initial position of the rotor assembly. The hub motor can accurately detect the initial position or the zero position of the motor rotor, so that the control precision of the controller on the hub motor is high.

Description

Technical Field

[0001] The utility model relates to the technical field of drive motors, in particular to a hub motor. Background Art

[0002] An electric power-assisted bicycle is composed of an ordinary bicycle with an additional drive motor. The drive motor is powered by a battery installed on the frame. The drive motor rotates to drive the electric power-assisted bicycle forward. The drive motor is generally installed in the front wheel hub or the rear wheel hub, so it is also called a hub motor.

[0003] In order to achieve precise control of the wheel hub motor, an encoder is installed in the wheel hub motor, so this type of wheel hub motor is also called a wheel hub motor with a built-in encoder. The encoder is particularly a magnetic encoder, and its structure includes a magnetic sensor installed on the stator assembly of the wheel hub motor and a signal magnetic ring installed on the rotor assembly. The signal magnetic ring rotates with the rotor assembly, and its magnetic field signal changes. The magnetic sensor detects the speed, position, angle and other information of the motor by sensing the change of the magnetic field signal of the signal magnetic ring, thereby achieving precise control of the wheel hub motor by the controller. The hub motor with built-in encoder in the related technology, such as the patent application with publication number CN219322159U and name of a hub motor with built-in encoder previously applied by the applicant in this case, has a magnetic sensor integrated on an annular circuit board, and the circuit board is connected to the ring groove of the stator, and the signal magnetic ring is installed on the rotor and located in the inner hole of the annular circuit board; under normal circumstances, after power failure and manual driving of the rotor to rotate or when disassembling and repairing, the zero position of the encoder will be offset, causing the controller to stall and the actual speed to be inconsistent with the set speed; for this reason, the hub motor with built-in encoder in the related technology has a zero position magnet fixedly connected to the rotor, attempting to detect the initial position or zero position of the motor rotor by sensing the magnetic field position of the zero position magnet through the magnetic sensor, so as to improve the control accuracy of the controller over the motor.

[0004] The above-mentioned hub motor of the related technology has the following deficiencies in actual use: the zero-position magnet fixedly connected to the rotor is a point-shaped or block-shaped permanent magnet, and the magnetic field area it generates is small; when the zero-position magnet rotates with the rotor, its magnetic field area or magnetic field signal is difficult to be sensed by the Hall sensor or sensing element integrated on the annular circuit board, so it is difficult to accurately detect the initial position or zero position of the motor rotor, resulting in low control accuracy of the controller over the hub motor. Utility Model Content

[0005] The technical problem to be solved by the present application is to overcome the defects of the above related technologies and provide a hub motor that can accurately detect the initial position or zero position of the motor rotor so that the controller can control the hub motor with high precision.

[0006] The technical solution of the present application is to provide a hub motor with the following structure: it includes a hub shell, a main shaft, a stator assembly, a rotor assembly, a magnetic encoder and a planetary reduction mechanism, the magnetic encoder includes a magnetic sensor connected to the stator assembly and a signal magnetic ring connected to the rotor assembly; it is characterized in that: a zero-position magnetic ring coaxial with the signal magnetic ring is connected to the rotor assembly, the zero-position magnetic ring includes at least one pair of magnets distributed in sequence along the circumferential direction, and the magnetic poles of each pair of magnets are opposite; at least one sensing element is integrated on the end face of the magnetic sensor, and the sensing element is used to sense the magnetic field change of the zero-position magnetic ring to detect the initial position of the rotor assembly.

[0007] In some embodiments, both of the two sensing elements protrude outwardly from the end surface of the magnetic sensor along the axial direction of the magnetic sensor, and the zero-position magnetic ring at least partially overlaps with the sensing elements along the radial direction.

[0008] In some embodiments, the two sensing elements form an inner circle coaxial with the magnetic sensor on the end face of the magnetic sensor, and the inner circle forms an annular space; the outer diameter of the zero-position magnetic ring is smaller than the diameter of the inner circle, and the zero-position magnetic ring is completely contained in the annular space.

[0009] In some embodiments, the sensing element is a Hall sensor integrated on the magnetic sensor circuit board for detecting magnetic field strength.

[0010] In some embodiments, the magnetic sensor includes a first annular circuit board and a second annular circuit board coaxially spaced apart, the first annular circuit board and the second annular circuit board being electrically connected; the signal magnetic ring is gap-fitted in the center hole of the first annular circuit board, and the first annular circuit board is circumferentially integrated with a plurality of chip elements for picking up the magnetic poles of the signal magnetic ring; the sensing element is integrated on the second annular circuit board.

[0011] In some embodiments, the stator assembly is provided with a first mounting portion for mounting the magnetic sensor, the rotor assembly is provided with a second mounting portion for mounting the signal magnetic ring and the zero position magnetic ring, and an annular groove for accommodating the magnetic encoder is formed between the first mounting portion and the second mounting portion.

[0012] In some embodiments, the magnetic sensor is connected to the side wall of the stator assembly in the annular groove via connecting screws, and a spacer sleeve capable of adjusting the axial position of the magnetic sensor is connected between the magnetic sensor and the side wall of the stator assembly.

[0013] In some embodiments, a shielding ring extending into the annular groove is connected to the stator assembly, and the shielding ring is located on a side of the magnetic sensor away from the spacer and at least partially overlaps with the magnetic sensor along the axial direction.

[0014] In summary, compared with the related art, a hub motor in the present application has the following advantages: the hub motor is integrated with at least one sensing element on the end face of the magnetic sensor, and a zero-position magnetic ring coaxial with the signal magnetic ring is connected to the rotor assembly, the zero-position magnetic ring includes at least one pair of magnets distributed in sequence along the circumferential direction, and the magnetic poles of each pair of magnets are opposite; taking the zero-position magnetic ring composed of a pair of magnets with opposite magnetic poles as an example, it has a clockwise or counterclockwise annular magnetic field and the magnetic field strength along the circumferential direction is distributed from strong to weak and from weak to strong from the N pole to the S pole, the sensing element can sense the strength of the magnetic field on the zero-position magnetic ring, and generate an electrical signal to feed back to the control circuit, so as to detect the initial position or zero position of the motor rotor, so that the controller has high control accuracy over the hub motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic cross-sectional structure diagram of a hub motor according to some embodiments of the present application.

[0016] Figure 2 is Figure 1 Schematic diagram of the enlarged structure of part A in FIG.

[0017] Figure 3 It is a schematic diagram of the structure of a magnetic encoder of a hub motor according to some embodiments of the present application.

[0018] Figure 4 It is a front structural schematic diagram of a magnetic encoder of a hub motor according to some embodiments of the present application.

[0019] Figure 5 This is a schematic diagram of the zero-position magnetic ring structure of a magnetic encoder of a hub motor according to some embodiments of the present application.

[0020] Description of reference numerals:

[0021] 1. Hub shell, 2. Main shaft, 3. Stator assembly, 300. First mounting part, 4. Rotor assembly, 400. Second mounting part, 5. Magnetic encoder, 500. Magnetic sensor, 501. Signal magnetic ring, 502. Gasket, 503. First annular circuit board, 504. Second annular circuit board, 505. Sensing element, 506. Inner circle, 507. Annular space, 6. Zero position magnetic ring, 7. Spacer, 8. Planetary reduction mechanism, 9. Connecting screws, 10. Shielding ring, 11. Annular groove. DETAILED DESCRIPTION

[0022] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0023] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0024] In the embodiments of the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0025] The utility model is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figures 1 to 5 As shown; the embodiment of the present application discloses a hub motor, including a hub shell 1, a main shaft 2, a stator assembly 3, a rotor assembly 4, a magnetic encoder 5 and a planetary reduction mechanism 8. The hub shell 1 is spliced ​​by a left shell and a right shell, and the left shell and the right shell are rotatably connected to the main shaft 2 through bearings. The stator assembly 3 is fixedly mounted on the main shaft 2 in the hub shell 1 through a stator bracket, and the rotor assembly 4 is rotatably connected to the main shaft 2 in the hub shell 1 through a bearing. The magnetic steel of the rotor assembly 4 is arranged opposite to the coil winding on the stator assembly 3, and the planetary reduction mechanism 8 is arranged in the hub shell 1. The sun gear of the planetary reduction mechanism 8 is rotatably connected to the main shaft 2 and fixedly connected to the rotor assembly 4. The sun gear drives the hub shell 1 to rotate through the transmission of the planetary gears, that is, the hub motor of this embodiment is an outer rotor hub motor.

[0027] In this embodiment, the wheel hub motor is equipped with a magnetic encoder 5, which is used to detect the speed, position, angle and other information of the motor, so as to realize the precise control of the wheel hub motor by the controller; specifically, the magnetic encoder 5 includes a magnetic sensor 500 connected to the stator assembly 3 and a signal magnetic ring 501 connected to the rotor assembly 4; the magnetic sensor 500 includes a first annular circuit board 503, the signal magnetic ring 501 is loosely fitted in the center hole of the first annular circuit board 503, and the first annular circuit board 503 is integrated with a plurality of chip components for picking up the magnetic poles of the signal magnetic ring 501 along the circumferential direction; the signal magnetic ring 501 is an annular magnet composed of multiple pairs of magnetic poles, and the chip components integrated on the magnetic sensor 500 are used to pick up the magnetic poles of the signal magnetic ring 501 and feed back to the controller, and the controller encodes each magnetic pole of the signal magnetic ring 501 to detect the speed of the rotor. It is a conventional technical means in the prior art to realize the precise control of the speed of the wheel hub motor by the magnetic encoder 5, and its control principle and encoding principle are also conventional technical means, which will not be described in detail in this embodiment.

[0028] Specifically in this embodiment, Figure 2 and Figure 3 As shown, at least one induction element 505 is integrated on the end surface of the magnetic sensor 500, and a zero position magnetic ring 6 coaxial with the signal magnetic ring 501 is connected to the rotor assembly 4. The zero position magnetic ring 6 includes at least one pair of magnets distributed in sequence along the circumferential direction, and the magnetic poles of each pair of magnets are opposite; the induction element 505 is used to sense the magnetic field change of the zero position magnetic ring 6 to detect the initial position of the rotor assembly 4. Take the zero position magnetic ring 6 composed of a pair of magnets with opposite magnetic poles as an example, see Figure 5 As shown, it has a clockwise annular magnetic field and the magnetic field strength along the circumferential direction is distributed from strong to weak and from weak to strong from the N pole to the S pole. The sensing element 505 can sense the strength of the magnetic field on the zero-position magnetic ring 6 and generate an electrical signal to feed back to the control circuit, so as to detect the initial position or zero position of the motor rotor, so that the controller has high control accuracy over the hub motor.

[0029] It is not difficult to understand that, see Figure 5 As shown, there is a pair of zero-position magnetic rings 6 of magnets, a semicircular N-pole magnet and a semicircular S-pole magnet, the strength of the magnetic field in the upper half is distributed from strong to weak and then from weak to strong from the N-pole to the S-pole, and similarly, the strength of the magnetic field in the lower half is distributed from strong to weak and then from weak to strong from the N-pole to the S-pole; that is, the magnetic field strength at the N-pole and the S-pole is stronger, the closer to the N-pole or the S-pole direction, the stronger the magnetic field strength, and the farther away from the N-pole or the S-pole direction, the weaker the magnetic field strength; its magnetic field is a ring-shaped distributed magnetic field, and the sensing element 505 can easily sense the strength of the magnetic field of the zero-position magnetic ring 6, thereby accurately judging the initial position of the rotor assembly 4.

[0030] In other embodiments, the zero-position magnetic ring 6 may also be composed of two pairs of magnets, or three pairs of magnets, or four pairs of magnets. For example, if it is composed of three pairs of magnets, the magnetic poles of the six magnets of the three pairs of magnets are distributed in a ring shape in the circumferential direction as N pole, S pole, N pole, S pole, N pole, and S pole; the magnetic poles of the four magnets of the two pairs of magnets are distributed in a ring shape in the circumferential direction as N pole, S pole, N pole, and S pole.

[0031] Specifically in this embodiment, the magnetic sensor 500 further includes a second annular circuit board 504, which is coaxial with the first annular circuit board 503 and spaced apart, and the second annular circuit board 504 is electrically connected to the first annular circuit board 503; the sensing element 505 is integrated on the second annular circuit board 504; specifically, there are two sensing elements 505, which are spaced apart along the circumference of the end surface of the magnetic sensor 500, that is, the two sensing elements 505 are distributed along the circumference of the second annular circuit board 504. Figure 4 As shown, two sensing elements 505 form an inner circle 506 coaxial with the magnetic sensor 500 on the end surface of the magnetic sensor 500, and an annular space 507 is formed inside the inner circle 506. In order to enable the sensing elements 505 to always sense the magnetic field of the zero-position magnetic ring 6, the two sensing elements 505 protrude outward from the end surface of the magnetic sensor 500 along the axial direction of the magnetic sensor 500, the outer diameter of the zero-position magnetic ring 6 is smaller than the diameter of the inner circle 506, and the zero-position magnetic ring 6 at least partially overlaps with the sensing elements 505 in the radial direction.

[0032] In the above embodiment, the two sensing elements 505 simultaneously detect the strength of the annular magnetic field generated by the zero position magnetic ring 6 at different positions, thereby accurately and quickly determining the initial position or zero position of the rotor assembly.

[0033] In a preferred embodiment, the zero-position magnetic ring 6 is completely contained in the annular space 507 formed by the inner circle 506 , so that the sensing element 505 can quickly sense the strength of the magnetic field of the zero-position magnetic ring 6 .

[0034] In the above embodiment, for the sake of clear description, the inner circle 506 is a virtual circle that does not actually exist, that is, a circle centered on the center line of the second annular circuit board 504 and formed by the inner walls of the two sensing elements 505 as boundaries. The space within the circle is the above-mentioned annular space 507.

[0035] In some embodiments, the two sensing elements 505 are Hall sensing elements integrated on the magnetic sensor 500 circuit board for detecting magnetic field strength. Specifically, the two sensing elements 505 are integrated on the second annular circuit board 504. In other embodiments, they can also be sensing chips or magnetoresistive sensors.

[0036] In some embodiments, Figure 1 and Figure 2As shown, in order to avoid the magnetic field of the rotor magnet from interfering with the magnetic encoder 5, the stator assembly 3 is provided with a first mounting portion 300 for mounting the magnetic sensor 500, and the rotor assembly 4 is provided with a second mounting portion 400 for mounting the signal magnetic ring 501 and the zero position magnetic ring 6. An annular groove 11 for accommodating the magnetic encoder 5 is formed between the first mounting portion 300 and the second mounting portion 400. The setting of the annular groove 11 makes the magnetic encoder 5 in a space away from the rotor magnet, so that the magnetic field of the rotor magnet can be effectively avoided from interfering with the magnetic encoder 5, so as to improve the detection accuracy; further, the stator assembly 3 is connected with a shielding ring 10 extending into the annular groove 11, and the shielding ring 10 is located on the side of the magnetic sensor 500 away from the spacer 7 and at least partially overlaps with the magnetic sensor 500 along the axial direction. The setting of the shielding ring 10 is used to further shield the magnetic field of the rotor magnet and further improve the detection accuracy of the magnetic encoder 5.

[0037] In some embodiments, Figure 1 and Figure 2 As shown, in order to make the axial position of the magnetic sensor 500 adjustable and enable the magnetic sensor 500 to better cooperate with the signal magnetic ring 501 and the zero position magnetic ring 6, the magnetic sensor 500 is connected to the side wall of the stator assembly 3 in the annular groove through the connecting screws 9 and the gasket 502, and a spacer 7 that can adjust the axial position of the magnetic sensor 500 is connected between the magnetic sensor 500 and the side wall of the stator assembly 3. The axial position of the magnetic sensor 500 is adjusted by adjusting the length of the spacer 7.

[0038] In the description of the embodiments of the present application, it should be noted that in the description of the present application, terms such as "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description, and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present application.

[0039] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0040] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A hub motor, comprising a hub shell, a main shaft, a stator assembly, a rotor assembly, a magnetic encoder and a planetary reduction mechanism, wherein the magnetic encoder comprises a magnetic sensor connected to the stator assembly and a signal magnetic ring connected to the rotor assembly; characterized in that: A zero-position magnetic ring coaxial with the signal magnetic ring is connected to the rotor assembly, and the zero-position magnetic ring includes at least one pair of magnets distributed in sequence along the circumferential direction, and the magnetic poles of each pair of magnets are opposite; at least one sensing element is integrated on the end face of the magnetic sensor, and the sensing element is used to sense the magnetic field change of the zero-position magnetic ring to detect the initial position of the rotor assembly.

2. The hub motor according to claim 1, characterized in that: There are two sensing elements, which are spaced apart and distributed along the circumferential direction of the end surface of the magnetic sensor.

3. The hub motor according to claim 2, characterized in that: The two sensing elements both protrude outwardly from the end surface of the magnetic sensor along the axial direction of the magnetic sensor, and the zero-position magnetic ring at least partially overlaps with the sensing elements along the radial direction.

4. The hub motor according to claim 3, characterized in that: The two sensing elements form an inner circle coaxial with the magnetic sensor on the end surface of the magnetic sensor, and the inner circle forms an annular space; the outer diameter of the zero position magnetic ring is smaller than the diameter of the inner circle, and the zero position magnetic ring is completely accommodated in the annular space.

5. The hub motor according to any one of claims 1 to 4, characterized in that: The sensing element is a Hall sensor element integrated on the magnetic sensor circuit board for detecting the strength of the magnetic field.

6. The wheel hub motor according to claim 1, characterized in that: The magnetic sensor includes a first annular circuit board and a second annular circuit board which are coaxially spaced apart, and the first annular circuit board and the second annular circuit board are electrically connected; the signal magnetic ring is gap-fitted in the center hole of the first annular circuit board, and the first annular circuit board is circumferentially integrated with a plurality of chip elements for picking up the magnetic poles of the signal magnetic ring; the sensing element is integrated on the second annular circuit board.

7. The hub motor according to claim 1, characterized in that: The stator assembly is provided with a first mounting portion for mounting the magnetic sensor, the rotor assembly is provided with a second mounting portion for mounting the signal magnetic ring and the zero position magnetic ring, and an annular groove for accommodating the magnetic encoder is formed between the first mounting portion and the second mounting portion.

8. The hub motor according to claim 7, characterized in that: The magnetic sensor is connected to the side wall of the stator assembly in the annular groove through a connecting screw, and a spacer sleeve capable of adjusting the axial position of the magnetic sensor is connected between the magnetic sensor and the side wall of the stator assembly.

9. The wheel hub motor according to claim 8, characterized in that: A shielding ring extending into the annular groove is connected to the stator assembly. The shielding ring is located on a side of the magnetic sensor away from the spacer sleeve and at least partially overlaps with the magnetic sensor along the axial direction.

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