Single-phase axial magnetic circuit brushless direct current actuator with absolute angle detection

Abstract

The single-phase axial magnetic circuit brushless direct current actuator with the absolute angle detection function comprises a stator, a rotor, a cover cap and a bearing, the rotor is coaxially erected on the stator in a positioned mode through the bearing, the cover cap is fixed to the opening side, provided with the rotor, of the stator, and the stator comprises 2N (N is a natural number of at least one) iron cores, 2N frameworks, a base and a coil. The iron core is sleeved in the framework, the coil is wound on the framework, the base and the iron core are spliced to form a closed magnetic circuit, the rotor comprises a shaft, a target support and a target, the target is fixed on the target support and can rotate along with the shaft, the cover comprises a cover shell, a PCB and a transmitting detection coil, the transmitting detection coil is arranged on the PCB and is coaxial with the shaft, and the coil is wound on the coil. And the target and the transmitting detection coil are axially arranged oppositely. According to the actuator in some embodiments, the problem of signal drifting caused by interference of an external common magnetic field and environment temperature changes can be solved, and the angle control precision of the actuator is greatly improved.

Description

Technical Field

[0001] The invention relates to a single-phase axial magnetic circuit brushless DC actuator, belongs to the field of brushless DC motors, and particularly relates to a single-phase axial magnetic circuit brushless DC actuator with absolute position detection. Background Art

[0002] The single-phase axial magnetic circuit brushless DC actuator can be used as a limited angle actuator. The usual structural arrangement includes: a single-phase multi-pair magnetic pole motor stator and a multi-pair magnetic pole rotor installed coaxially and face-to-face in parallel, and a bearing that ensures that the stator and the rotor are arranged with a certain air gap and can rotate, usually a thrust bearing. The stator usually includes multiple pairs of iron cores, a skeleton corresponding to the iron core, a single-phase winding coil continuously wound on all the iron core skeletons, and a base for closing the magnetic circuit after assembly with the iron core. The rotor usually includes multiple pairs of magnetic pole magnets, a disc for closing the magnetic circuit after assembly with the magnets, and a rotating shaft that is positioned and rotated relative to the stator.

[0003] If the single-phase axial magnetic circuit brushless DC actuator needs to perform position control, it must have absolute angle detection and absolute angle closed-loop control. Common angle detection solutions often use magnetic sensitive detection. Although its application is mature, its accuracy is seriously challenged in high magnetic field interference environment due to its magnetic sensitive detection principle. For example, more and more electric vehicle applications require large current when driving, and there is a large electromagnetic radiation that will cause magnetic field interference. Moreover, its detection accuracy will drift with the change of temperature, resulting in reduced accuracy. It is insufficient for scenes with high magnetic field interference and the need for high-precision control. At the same time, the magnetic sensitive detection solution usually requires the transmitter magnet and the magnetic sensitive detection chip to be arranged at the shaft end, which creates difficulties for the structural arrangement that requires dual-cycle output, and the arrangement on the side of the shaft further leads to the asymmetry of the magnetic field and other problems that affect the accuracy. Summary of the invention

[0004] The purpose of the present invention is to propose a single-phase axial magnetic circuit brushless DC actuator with absolute angle detection based on the above background, the single-phase axial magnetic circuit brushless DC actuator with absolute angle detection includes: a stator, a rotor, a cover, and a bearing. The rotor is coaxially mounted on the stator through the bearing, and the cover is fixed to the stator frame with the stator opening side of the rotor. The stator includes 2N iron cores, 2N skeletons, a base, and a coil, wherein N is a natural number of at least 1, the iron core is sleeved in the skeleton, the coil is wound on the skeleton, and the base and the iron core are assembled to form a closed magnetic circuit, wherein the rotor includes a shaft, a target bracket, and a target, the target is fixed to the target bracket and can rotate with the shaft, the cover includes a cover shell, a PCB, and a transmitting detection coil, the transmitting detection coil is arranged on the PCB and coaxially arranged with the shaft, and the target and the transmitting detection coil are axially arranged opposite to each other.

[0005] According to an optional embodiment, the target only covers a portion of the transmitting and detecting coil when viewed axially; and / or the cover closes the stator on one side of the stator opening; and / or the rotor also includes a disc and a magnet, the axis is coaxially fixed vertically with the disc, the magnet and the target bracket are coaxially fixed on both sides of the disc relative to the axis, and the target is coaxially fixed to the target bracket relative to the axis; and / or the PCB also includes a processing chip, and the processing chip is used to process the signal generated by the transmitting and detecting coil; and / or the cover also includes PCB terminals and coil terminals, the PCB terminals are used for external electrical connection of the PCB, and the coil terminals are used for external electrical connection of the coil.

[0006] According to an optional embodiment, the transmitting detection coils are kept at a certain distance from the target and are arranged parallel to each other.

[0007] According to an optional embodiment, the target includes N (N is a natural number at least 1) metals that are coaxially arranged relative to the axis and evenly distributed around the circumference and are angularly symmetrical. Preferably, the target is configured as a PCB, the metal is copper foil, and the equally divided metal is fan-shaped.

[0008] According to an optional embodiment, the cover has at least three positioning posts, and the outer sides of the positioning posts are on a circumference, and the outer sides of the positioning posts are positioned and matched with the inner circle of the stator, so that the center of the cover is coaxially arranged relative to the center of the stator.

[0009] According to an optional embodiment, the cover has a PCB positioning column, and the PCB positioning column enables the center of the PCB transmitting and detecting coil to be coaxially arranged with the center of the outer circumference of the cover positioning column after being positioned relative to the cover.

[0010] According to an optional embodiment, the plane distance between the target and the rotor disk is at least twice the plane distance between the target and the transmitting detection coil.

[0011] According to an optional embodiment, the transmitting detection coil includes at least one transmitting coil and at least two detection coils.

[0012] According to an optional embodiment, the PCB is integrated with the processing chip to process and output analog and digital angle signals.

[0013] According to an optional embodiment, the PCB integrates a motor driver and a signal transceiver, and the actuator can be servo-controlled through signal transceiver communication. Preferably, the signal transceiver commonly used in automobiles is LIN or CAN communication.

[0014] The beneficial effects of the present invention are as follows: the actuator is arranged with a transmitting detection coil and a signal processing chip, the transmitting coil sends a signal that causes an electromagnetic signal change according to the rotational position change of the target, the detection coil calculates the change in absolute angle by detecting the change in the electromagnetic signal, the angle detection is not interfered by the external magnetic field of normal frequency, and is not changed by the change in ambient temperature, so there is no electromagnetic interference and temperature drift problem of commonly used magnetic sensors that leads to reduced accuracy, and a hole can be opened in the center of the target and the transmitting detection coil, which is an ideal arrangement for the output shaft arrangement scheme that requires perforation at both ends, while the conventional magnetic-sensitive absolute angle detection is arranged at one end of the rotor, which limits the application of dual-axis output.

[0015] The actuator of the present invention can avoid the interference of the general external magnetic field and the signal drift problem caused by the ambient temperature change, greatly increase the angle control accuracy of the actuator, the layout scheme is simple, and the cost is comparable to the usual magnetic sensitive scheme, and has extremely high technical and large-scale market application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is an isometric view of an actuator of an embodiment of the present invention.

[0017] Figure 2 It is a front view of the actuator according to the embodiment of the present invention.

[0018] Figure 3 It is a top view of the actuator according to the embodiment of the present invention.

[0019] Figure 4 The actuator of the embodiment of the present invention is along Figure 3 Cross-sectional view of AA in.

[0020] Figure 5 is an isometric view of an actuator rotor of an embodiment of the present invention.

[0021] Figure 6 It is a front view of the actuator rotor according to the embodiment of the present invention.

[0022] Figure 7 is an isometric view of an actuator cover of an embodiment of the present invention.

[0023] Figure 8 1 is a front view of an actuator cover according to an embodiment of the present invention. List of reference numerals: 1-cover, 11-cover shell, 12-clip, 13-PCB positioning column, 14-PCB, 141-PCB transmitting detection coil, 15-processing chip, 16-connector, 17-PCB terminal, 18-coil terminal, 19-limiting column 2-stator, 21-iron core, 22-skeleton, 23-coil, 24-base, 25-coating material, 26-sleeve, 27-glue groove, 28-claw, 29-inner circle of stator, 3-rotor 31-shaft, 311-D-shaped shaft, 32-disc, 33-magnet, 34-target bracket, 35-target, 351-target sensing fan-shaped metal, 4-bearing, 5-cover limit column positioning circle. Implementation

[0024] In order to explain the single-phase axial magnetic circuit brushless DC actuator with absolute angle detection in detail for better understanding, the single-phase axial magnetic circuit brushless DC actuator implementation example of the present invention is first explained. Figure 1 , Figure 2 , Figure 3 They are respectively an isometric view, a front view and a top view of an actuator according to an embodiment of the present invention. Figure 4 The actuator of the embodiment of the present invention is along Figure 3 The cross-sectional view taken along line AA in FIG. The specific implementation is as follows: the actuator generally comprises a cover 1, a stator 2, a rotor 3, and a bearing 4. The stator 2 comprises 2N (N is a natural number with a minimum value of 1) iron cores 21, 2N skeletons 22, 2N coils 23 connected end to end, a base 24, a coating material 25, and a sleeve 26; the rotor comprises a rotating shaft 31, a disc 32, a magnetic steel 33, a target bracket 34, and a target 35; the cover comprises a cover housing 11, a PCB 14, a PCB transmitting and detecting coil 141, and a processing chip 15.

[0025] The stator frame 22 is sleeved on the iron core 21, the coil 23 is sleeved in the frame 22, and 2N coils 23 are connected end to end to form a single-phase winding. The 2N iron cores 21 of the winding are inserted into the base 24 to form a stator assembly. The stator assembly is further integrally coated with a coating material 25, and the coating process simultaneously buries the sleeve 26 into the center of the stator 2 to become an integral part of the stator 2. The coating can be any similar process such as injection molding, epoxy glue potting, etc. After coating molding, the stator 2 also forms a plurality of claws 28 for interlocking with the buckle 12 of the cover 1. Of course, for those skilled in the art, the stator 2 and the cover 1 can be connected in many other possible ways, such as bolt fixing, adhesive bonding, laser welding, and any other structural design and process scheme that can fit and fix.

[0026] Furthermore, the structure of the absolute angle detection part of the single-phase axial magnetic circuit brushless DC actuator of the present invention is described in detail. Figure 5 , Figure 6 They are respectively an isometric view and a top view of the actuator rotor of an embodiment of the present invention, wherein the shaft 31 is coaxially fixedly connected to the disc 32, the magnetic steel 33 is coaxially fixedly connected to one side of the disc 32, the target bracket 34 is coaxially fixed to the other side of the disc 32 relative to the shaft 31, preferably, the target bracket 34 can be fitted and fixed to the disc 32, the target 35 is sleeved on the rotating shaft 31 and coaxially positioned and fixed relative to the target bracket 34, preferably, the mating part of the shaft and the target 35 is a D-shaped shaft 311, and the center of the target 35 is a corresponding D-shaped hole (see Figure 6 ), the D-type matching arrangement can effectively constrain the rotational positioning of the target, and the fixed surfaces of all the above-mentioned magnetic steel 33, disc 32, target bracket 34, and target 35 components are relatively parallel and fixed.

[0027] The target 35 includes N (N is a natural number at least 1) target sensing sector metals 351 evenly distributed around the circumference. Figure 6 The target sensing sector metal 351 is a single sector with an angle of 180°, or two sectors with a symmetrical distribution of 90°, or two or more target sensing sector metals 351 evenly distributed on the circumference. The target sensing sector metal 351 is coaxially arranged relative to the shaft 31. When the target 35 of the rotor 3 needs to constrain the relative installation angle with respect to the cover 1, the target 35 can be arranged in a specific manner, such as Figure 6 The D-shaped shaft 311 feature at the end of the central shaft 31 is used to position the rotation direction with the D-shaped hole that matches the center of the target. Preferably, the target 35 is usually a PCB, and the target sensing fan-shaped metal 351 is a copper foil. Of course, for technicians in this field, any other way to achieve rotational positioning of the target 35 relative to the shaft 31 is an optional design.

[0028] Figure 7 , Figure 8 They are respectively an isometric view and a front view of an actuator cover of an embodiment of the present invention, wherein the cover 1 comprises a cover shell 11, a PCB positioning column 13, and a PCB terminal 17 and a coil terminal 18 embedded in the cover shell 11, and the cover 1 also has at least three positioning columns 19, and the arrangement of the positioning columns 19 makes the outer side of the positioning columns 19 form a cover limit column positioning circle 5, when the cover 1 and the stator 2 are installed, the outer side of the cover positioning column 19 cooperates with the inner circle 29 of the stator, so that the center of the cover 1 and the center of the stator 2 are relatively coaxially positioned.

[0029] A PCB 14 and a PCB transmitting and detecting coil 141 embedded in the PCB 14 are arranged in the cover shell 11. The PCB 14 is positioned and fixed relative to the cover shell 11 by a PCB positioning column 13. The PCB positioning column 13 is coaxially arranged relative to the cover limit column positioning circle 5. The above arrangement enables the PCB transmitting and detecting coil 141 to be coaxially arranged relative to the axis 31 of the rotor 3 after the cover 1 is snap-connected and fixed to the stator 2. The PCB 14 has a corresponding number of connecting holes to the PCB terminals 17 and is reliably connected through electrical connection methods such as welding or insertion and snap-fitting.

[0030] In the present invention, the target 35 and the PCB transmitting detection coil 141 are arranged axially opposite to each other, but separated by a certain distance. Preferably, the PCB transmitting detection coil 141 is arranged in a ring shape, and the target 35 does not constitute a whole ring shape, so when viewed in the axial direction, the target 35 covers a part of the PCB transmitting detection coil 141.

[0031] The PCB 14 is also provided with a processing chip 15 and other necessary electronic components (not illustrated). The processing chip 15 controls the transmitting coil in the PCB transmitting detection coil 141 to emit an electromagnetic signal with a certain frequency characteristic, and detects the feedback electromagnetic signal through a plurality of detection coils arranged in the PCB transmitting detection coil 141. When the rotor 3 rotates relative to the fixedly connected cover 1 and the stator 2 relative to the central sleeve 26, the target induction sector metal 351 on the rotor 3 will cause the signal induction change emitted by the transmitting coil in the PCB transmitting detection coil 141, thereby causing the plurality of detection coils arranged in the PCB transmitting detection coil 141 to detect the change of the electromagnetic signal. The processing chip 15 processes and calculates the change law of the detected electromagnetic signal and calculates the relative rotation angle. Since the actuator is initially calibrated and the absolute zero position is marked by the processing chip 15, the absolute angle position relative to the zero point can be obtained through the above calculation processing.

[0032] The cover 1 also has a coil terminal 18. In view of the single-phase structure of the stator 2, there are two coil terminals 18 in this embodiment. The coil terminal 18 is used to be electrically connected to the terminal (not shown) connected to the base coil when the cover 1 is snap-connected with the stator 2. The cover 1 also has a characteristic part connector 16, which contains the PCB terminal and the other end of the coil terminal. When the actuator is electrically connected to the outside through the male and female connectors, the external drive control of the actuator is realized. When the external current excites the coil 23 in the stator 2 of the actuator through the PCB terminal 17 of the cover 1, the rotation of the rotor 3 can be driven, and the absolute angle position can be calculated by the processing chip 15, so that the external can realize the precise angle control of the actuator.

[0033] When the PCB 14 in the actuator is directly arranged with additional driver chips and driver electronics, the actuator can achieve independent servo control.

[0034] The stator 2 has a glue groove 27. When the buckle 12 on the cover is fixed to the claw 28 on the stator, the glue groove 27 is filled with glue, which can achieve effective sealing of the actuator.

[0035] The beneficial effects of the present invention are as follows: the actuator is arranged with a transmitting detection coil and a signal processing chip, the transmitting coil emits an electromagnetic signal which changes according to the rotational position of the target, the detection coil calculates the change in the absolute angle by detecting the change in the electromagnetic signal, the angle detection is not interfered by the external magnetic field of normal frequency, and is not changed by the change in ambient temperature, so there is no electromagnetic interference and temperature drift problem of the commonly used magnetic sensitive sensors which leads to reduced accuracy, and a hole can be opened in the center of the target and the transmitting detection coil, which is an ideal arrangement for the arrangement of the output shafts that require perforation at both ends, while the conventional magnetic sensitive absolute angle detection is arranged at one end of the rotor, which limits the application of dual-axis output.

[0036] The actuator of the present invention avoids the interference of the general external magnetic field and the signal drift problem caused by the ambient temperature change, greatly increases the angle control accuracy of the actuator, has a simple layout, and the cost is comparable to that of the usual magnetic sensitive solution. It has extremely high technical and large-scale market application value.

[0037] The above is only a preferred embodiment of the present invention. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection of the present invention is not limited to the above-mentioned implementation mode, nor does it limit the scope of patent protection of the present invention. All structural derivative transformations made by using the contents of the present invention specification and drawings under the above invention concept, directly or indirectly applied to other technical fields, are included in the scope of patent protection of the present invention.

Claims

1. A single-phase axial magnetic circuit brushless DC actuator with absolute angle detection, comprising a stator, a rotor, a cover, and a bearing, wherein the rotor is coaxially mounted on the stator through the bearing, the cover is fixed to the stator frame at one side of the stator opening where the rotor is mounted, the stator comprises 2N iron cores, 2N frames, a base, and a coil, wherein the iron core is sleeved in the frame, wherein: N is a natural number of at least 1, the coil is wound on the frame, the base and the iron core are assembled to form a closed magnetic circuit, characterized in that: The rotor includes a shaft, a target support, and a target, wherein the target is fixed to the target support and can rotate along with the shaft. The cover comprises a cover shell, a PCB, and a transmitting and detecting coil. The transmitting and detecting coil is arranged on the PCB and coaxially with the axis, and the target is arranged axially opposite to the transmitting and detecting coil.

2. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection according to claim 1, characterized in that: The target only covers a portion of the transmitting and detecting coils when viewed axially; and / or The cover closes the stator on one side of the stator opening; and / or The rotor further comprises a disc and a magnetic steel, the shaft is fixed coaxially and vertically with the disc, the magnetic steel and the target bracket are fixed coaxially with respect to the axis on both sides of the disc respectively, and the target is fixed coaxially with respect to the axis to the target bracket; and / or The PCB further comprises a processing chip, wherein the processing chip is used to process the signal generated by the transmitting detection coil; and / or The cover also includes a PCB terminal and a coil terminal. The PCB terminal is used for external electrical connection of the PCB, and the coil terminal is used for external electrical connection of the coil.

3. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection according to claim 2, characterized in that: The transmitting and detecting coils are kept at a certain distance from the target and are arranged parallel to each other.

4. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection according to any one of claims 1 to 3, characterized in that: The target includes N metals that are coaxially arranged relative to the axis and equally distributed around the circumference and are angularly symmetrical. Preferably, the target is configured as a PCB, the metal is copper foil, and the equally divided metals are fan-shaped.

5. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection according to any one of claims 1 to 3, characterized in that: The cover has at least three positioning posts, and the outer sides of the positioning posts are on a circumference. The outer sides of the positioning posts are positioned and matched with the inner circle of the stator, so that the center of the cover is coaxially arranged relative to the center of the stator.

6. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection according to any one of claims 1 to 3, characterized in that: The cover has a PCB positioning column, and the PCB positioning column enables the center of the PCB transmitting and detecting coil after being positioned relative to the cover to be coaxially arranged with the center of the outer circle of the cover positioning column.

7. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection according to claim 2, characterized in that: The plane distance between the target and the rotor disk is at least twice the plane distance between the target and the transmitting detection coil.

8. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection according to any one of claims 1-3 and 7, characterized in that: The transmitting and detecting coils include at least one transmitting coil and at least two detecting coils.

9. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection according to claim 2, characterized in that: The PCB is integrated with the processing chip for processing and outputting analog and digital angle signals.

10. The single-phase axial magnetic circuit brushless DC actuator with absolute angle detection according to claim 9, characterized in that: The PCB integrates a motor driver and a signal transceiver, and the actuator can be servo-controlled through communication with the signal transceiver.

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