A brushless slotless motor with a phase adjustment structure

Abstract

The application relates to a brushless and slotless motor with a phase adjustment structure, which comprises a wire cover assembly, a stator-rotor assembly, an insulating sheet and a Hall magnetic steel, the wire cover assembly comprises a wire harness and a PCB board on which a Hall sensor is mounted, the wire cover assembly further comprises first pouring sealant for fixing the wire harness and the PCB board, and the motor further comprises second pouring sealant for fixing the PCB board and the wire harness. Compared with the prior art, the application has the advantages of saving cost, realizing micro motor phase adjustment, shortening the size chain, improving the inductive distance precision, improving the ability of resisting extreme environment and the like.

Description

Technical Field

[0001] This invention relates to a brushless cogging motor, and more particularly to a brushless cogging motor with a phase adjustment structure. Background Technology

[0002] Compared to traditional cogging motors, brushless cogging motors offer advantages such as high power density, high efficiency, no cogging effect, smooth speed curve, low noise, and fast response. Brushless cogging motors require a device to detect the rotor position. Known solutions include using magnets and Hall effect position sensors; magnets and magnetic encoder chips; and optical encoders and optical encoder chips to determine rotor position. Motors with built-in Hall effect position sensors require ensuring the relative phase relationship between the sensor signal and the motor's back EMF signal to guarantee optimal motor output. Common brushless cogging motor structures include: stator assembly, rotor assembly, and circuit board assembly. The circuit board assembly can be installed inside or outside the motor. Installing the circuit board assembly externally offers the following advantages over internal placement: 1. The main magnet no longer functions as a Hall effect magnet, allowing for perfect alignment with the stator core and reducing axial magnetic pull; 2. The bearing spacing is shortened. For micro motors, especially rotor structures with shaft diameters below 4mm, shorter bearing spacing increases rotor rigidity and reduces vibration. 3. The winding taps and PCB board can be soldered after the phase adjustment is completed. There will be no situation where the reserved length of the winding taps is insufficient after soldering, making the phase adjustment more reliable, safe and convenient.

[0003] The specific structure of the circuit board assembly outside the motor is proposed by patent CN213425971U, such as... Figure 1 As shown, however, it is not suitable for motors with smaller outer diameters (below φ13mm). Because the mounting bracket provides axial and radial support to the PCB, it further reduces the PCB's outer diameter, making it impossible to arrange the Hall sensor, winding tap vias, and wire harness soldering holes. The windings generally use multi-strand wire, and the tap wire diameter is relatively large; the mounting bracket with a smaller outer diameter cannot provide the radial space required for the clearance structure. The sensing distance F between the Hall magnet and the Hall sensor is F = LBS, where the tolerance of the Hall sensor patch height B is relatively large, reaching ±0.1mm, resulting in a wide tolerance band for the sensing distance F, affecting control accuracy. Therefore, patent CN217445153U provides a brushless, slotless structure, such as... Figure 2 As shown, the PCB board has been fitted with notches and connected to waist-shaped solder holes to facilitate the adjustment of the phase relationship between the sensor signal and the motor back EMF signal. This addresses the problems of complex circuitry in the middle area of ​​the PCB, limited through-hole area, difficulty and limitation in adjusting the PCB angle after wiring, and increased production complexity.

[0004] However, coreless motors are generally small in size and cannot provide large through holes for wires. This patent still uses increasing the size of the through holes as an improvement solution, which does not achieve the desired effect.

[0005] In addition, the electrical connections between the Hall sensor and the PCB board, as well as the three-phase lines and the PCB board, are exposed. Under certain operating conditions, the electrical connections of the Hall sensor and the three-phase lines are prone to failure, especially in medical sterilization environments. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a phase adjustment structure for a brushless, coggingless motor.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] According to one aspect of the present invention, a brushless coggingless motor with a phase adjustment structure is provided, comprising a wire cover assembly, a stator and rotor assembly, an insulating sheet and a Hall magnet, wherein the wire cover assembly comprises a circuit board assembly and a wire cover, the circuit board assembly comprises a PCB board on which a Hall sensor is mounted and a wire harness, the wire cover assembly further comprises a first potting compound for fixing the circuit board assembly and the wire cover, and the motor further comprises a second potting compound for fixing the PCB board and the wire harness.

[0009] As a preferred technical solution, the stator and rotor assembly includes a stator assembly, a rotor assembly, and a rear end cover with through holes. The three-phase windings of the rotor assembly pass through the through holes of the rear end cover and are electrically connected to the PCB board. An insulating sleeve is arranged between the three-phase windings and the through holes of the rear end cover.

[0010] As a preferred technical solution, the insulating sleeve is a heat shrink tubing.

[0011] As a preferred technical solution, the PCB board is provided with a first potting port, through which glue is poured to form a whole between the PCB board and the wire cover, and a first potting glue structure is formed by using a corresponding potting tool.

[0012] As a preferred technical solution, the first potting compound has three evenly distributed through holes, the through holes are shaped like truncated cones, and the angle between the through hole profile and the axis is α, wherein the range of α is 5° < α < 30°.

[0013] As a preferred technical solution, the wire cover assembly is formed by an interference fit between the wire cover and the rear cover.

[0014] As a preferred technical solution, three Hall sensors are mounted on the PCB board, evenly distributed on the circle φD at 120° intervals.

[0015] As a preferred technical solution, the viscosity of the first potting compound and the second potting compound is less than...

[0016] 3000cps@25℃, while the curing temperature of the adhesive must not exceed the temperature resistance of the motor.

[0017] As a preferred technical solution, the line cover is provided with a flange structure, which forms a second glue inlet. The flange structure is provided with at least two flange notches, which serve as the force points for the phase adjustment tool.

[0018] As a preferred technical solution, the distance from the end face of the Hall magnet to the end face of the Hall sensor is F1 = L1 - S1, where S1 is the distance between the end face of the Hall magnet and the stop of the rear cover, and L1 is the distance from the mating end face of the wire cover to the end face of the Hall sensor.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1) It can realize the phase adjustment of micro motors, and the function of the mounting bracket is replaced by potting and insulating sheets, saving costs;

[0021] 2) The size chain is shortened, and the link with the largest tolerance is eliminated, resulting in higher sensing distance accuracy;

[0022] 3) The electrical connection points between the Hall sensor and the PCB board, and between the three-phase lines and the PCB board, are sealed with potting compound, making the PCB board more resistant to extreme environments, such as sterilization environments. Attached Figure Description

[0023] Figure 1 The structural diagram is for the existing patent CN213425971U;

[0024] Figure 2 This is a partial enlarged view of existing patent CN213425971U;

[0025] Figure 3 The structural diagram is for the existing patent CN217445153U;

[0026] Figure 4 This is an end view of the wire cover assembly of the present invention;

[0027] Figure 5 This is a view of the other end face of the wire cover assembly of the present invention;

[0028] Figure 6 This is a CC cross-sectional view of the wire cover assembly of the present invention;

[0029] Figure 7 This is an assembly drawing of the motor of the present invention;

[0030] Figure 1 As indicated by the standard number:

[0031] 7. Stator assembly; 8. Rotor assembly; 9. Enlarged portion of existing patent CN213425971U; 12. Circuit board assembly; 13. Spacing structure.

[0032] Figure 4 As indicated by the standard number:

[0033] 101. Flanged edge of the wire cover; 102. Flanged notch; 103. Second glue inlet;

[0034] Figure 5 As indicated by the standard number:

[0035] 1201. Hall effect sensor;

[0036] Figure 6 As indicated by the standard number:

[0037] 10. Wire cover; 100. Wire cover mating end face; 11. First potting compound; 110. Through hole; 12. Circuit board assembly; 120. PCB board; 1200. First potting port; 12010. Hall sensor end face; 121. Wire harness.

[0038] Figure 7 As indicated by the standard number:

[0039] 1. Wire cover assembly; 2. Stator and rotor assembly; 20. Rear end cover; 200. Rear end cover stop; 201. Rear end cover through hole; 3. Heat shrink tubing; 4. Insulating sheet; 5. Hall magnet; 6. Second potting compound. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0041] Due to the absence of core slots in the stator of a brushless, coggingless motor, the phases of the shaped coils lack clear positioning. Furthermore, considering the magnetization angle error of the magnet itself and the angle error of the Hall effect sensor patch, in motors with Hall effect magnets, the magnetic poles of the Hall effect magnets must correspond to the magnetic poles of the rotor's main magnets during assembly. This process inevitably introduces assembly errors. Therefore, it is necessary to adjust the angle of the PCB board where the Hall effect position sensor is located to ensure the phase relationship between the sensor signal and the motor's back EMF signal.

[0042] like Figure 7As shown, the present invention provides a brushless coggingless motor with a phase adjustment structure, which is particularly suitable for micro motors. The motor includes a wire cover assembly 1, a stator and rotor assembly 2, an insulating sheet 4, and a Hall magnet 5. The wire cover assembly 1 includes a circuit board assembly 12 and a wire cover 10. The circuit board assembly 12 includes a PCB board 120 on which a Hall sensor 1201 is mounted and a wire harness 121. The wire cover assembly 1 also includes a first potting compound 11 for fixing the circuit board assembly 12 and the wire cover. The motor also includes a second potting compound 6 for fixing the PCB board 120 and the wire harness 121.

[0043] like Figure 4-6 As shown, the stator and rotor assembly 2 includes a stator assembly 7, a rotor assembly 8, and a rear end cover 20 with through holes. The three-phase windings of the stator assembly 7 pass through the through holes 201 of the rear end cover 20 and are electrically connected to the PCB board 120. An insulating sleeve 3 is arranged between the three-phase windings and the through holes 201 of the rear end cover 20.

[0044] The wire cover and circuit board assembly are bonded and fixed together using a first potting compound. The potting compound needs to have a low viscosity to facilitate potting and leveling; a viscosity of less than 3000 cps at 25℃ is recommended. The curing temperature of the compound should not exceed the motor's temperature resistance, and it should have sufficient bonding strength after curing. During potting, the relative positional relationship between the circuit board assembly and the wire cover must be maintained. Preferably, the distance L1 from the mating end face of the wire cover to the end face of the Hall sensor is controlled using the mating end face of the wire cover as a reference.

[0045] The PCB board contains three Hall sensors, which are evenly distributed at 120° intervals on a circle with a diameter of φD. The distance from the end face of the Hall magnet to the end face of the Hall sensor is F1 = L1 - S1, where S1 is the distance between the end face of the Hall magnet and the rear cover stop, and L1 is the distance from the mating end face of the wire cover to the end face of the Hall sensor. φD and F1 need to be simulated and designed according to the requirements of the Hall sensors. The PCB board has a central hole, which serves as the first potting port. This first potting port allows the first and second potting compounds on both sides of the PCB board to form a unified whole, increasing the overall vibration and shock resistance of the wire cover assembly and making it more reliable.

[0046] The wire cover 10 has a flanged structure that forms a second potting port 103. The flanged structure has at least two flanged notches 102, which serve as the leverage points for the phase adjustment fixture. The fixture increases the lever arm to overcome the interference force between the wire cover and the rear end cover, facilitating phase adjustment. Simultaneously, the notches further increase the bonding strength between the PCB board and the wire cover after the second potting, making the wire cover assembly more reliable.

[0047] The stator and rotor assembly includes a stator assembly, a rotor assembly, and a rear end cover with through-holes. The rear end cover has three through-holes through which the three-phase windings of the rotor assembly pass, electrically connecting to the PCB board. Insulating sleeves (heat-shrink tubing) are placed between the three-phase windings and the through-holes in the rear end cover to provide insulation while minimizing radial space occupation. The wire cover assembly is interference-fitted with the rear end cover. This interference force ensures that, after phase adjustment, the position of the wire cover assembly relative to the stator and rotor assemblies remains unchanged before the rigid connection between the wire cover and the rear end cover, thus maintaining the ideal phase relationship after adjustment.

[0048] Based on the technical concept of this invention, the potting process is performed in two stages. The first stage involves fixing the PCB board, and the second stage is performed after phase adjustment and soldering of the three-phase lines. During the first potting stage, three vias with a truncated cone shape are required. The angle between the via profile and the axis is α, with α recommended to be within the range of 5° < α < 30°. The vias furthest from the PCB board end have a larger diameter and a rounded transition to the end face to protect the enameled wire from damage when the three-phase lines retract during phase adjustment.

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A brushless coggingless motor with a phase adjustment structure, comprising a wire cover assembly (1), a stator and rotor assembly (2), an insulating sheet (4), and a Hall magnet (5), wherein the wire cover assembly (1) comprises a circuit board assembly (12) and a wire cover (10), and the circuit board assembly (12) comprises a PCB board (120) on which a Hall sensor (1201) is mounted and a wire harness (121), characterized in that, The wire cover assembly (1) further includes a first potting compound (11) for fixing the circuit board assembly (12) and the wire cover (10). The motor further includes a second potting compound (6) for fixing the PCB board (120) and the wire harness (121). The first potting compound (11) has three evenly distributed vias (110). The vias (110) are shaped like a truncated cone. The angle between the outline of the vias (110) and the axis is α, and the range of α is 5° < α < 30°.

2. The brushless coggingless motor with a phase adjustment structure according to claim 1, characterized in that, The stator and rotor assembly (2) includes a stator assembly (7), a rotor assembly (8), and a rear end cover (20) with through holes. The three-phase windings of the stator assembly (7) pass through the through holes (201) of the rear end cover (20) and are electrically connected to the PCB board (120). An insulating sleeve (3) is arranged between the three-phase windings and the through holes (201) of the rear end cover (20).

3. A brushless coggingless motor with a phase adjustment structure according to claim 2, characterized in that, The insulating sleeve (3) is a heat shrink tubing.

4. A brushless coggingless motor with a phase adjustment structure according to claim 1, characterized in that, The PCB board (120) and the wire cover (10) are integrated by applying glue through the first potting port (120) provided on the PCB board (120), and the first potting glue (11) structure is formed by using the corresponding potting tool.

5. A brushless coggingless motor with a phase adjustment structure according to claim 1, characterized in that, The wire cover assembly (1) is interference-fitted with the wire cover (10) and the rear cover (20).

6. A brushless coggingless motor with a phase adjustment structure according to claim 1, characterized in that, Three Hall sensors (1201) are mounted on the PCB board (120), which are evenly distributed on the circle φD at 120° intervals.

7. A brushless coggingless motor with a phase adjustment structure according to claim 1, characterized in that, The viscosity of the first potting compound (11) and the second potting compound (6) is less than 3000 cps@25℃, and the curing temperature of the adhesive must not exceed the temperature resistance of the motor.

8. A brushless coggingless motor with a phase adjustment structure according to claim 1, characterized in that, The line cover (10) is provided with a flange structure, which forms a second glue inlet (103). The flange structure is provided with at least two flange notches (102), which serve as the force points for the phase adjustment tool.

9. A brushless coggingless motor with a phase adjustment structure according to claim 1, characterized in that, The distance F1 from the end face of the Hall magnet (5) to the end face of the Hall sensor (12010) is L1-S1, where S1 is the distance between the end face of the Hall magnet (5) and the stop (200) of the rear cover, and L1 is the distance from the end face of the wire cover (100) to the end face of the Hall sensor (12010).

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