A servo motor

Abstract

The application discloses a servo motor, which comprises a motor shell, an inductor, an inner shielding cover and a filter circuit board. The motor shell is internally provided with the inductor; the inner shielding cover is arranged in the motor shell, the inner shielding cover is provided with a shielding cavity, and the inductor is arranged in the shielding cavity; and the filter circuit board is arranged in the motor shell and electrically connected with the inner shielding cover. The inner shielding cover is arranged in the motor shell, which is helpful to avoiding changing the overall installation space and size of the motor shell, thereby avoiding increasing the production cost of the motor. Meanwhile, the inner shielding cover and the filter circuit board can suppress the magnetic flux leakage of the inductor in two stages, thereby suppressing the electromagnetic interference generated in the servo motor, and the filtering effect is good.

Description

Technical Field

[0001] This utility model generally relates to the field of electronic information equipment technology, and in particular to a servo motor. Background Technology

[0002] Servo motors have a high electromagnetic interference problem. In related technologies, the filtering circuit and filter to suppress electromagnetic interference are placed externally and not installed separately inside the servo motor housing.

[0003] However, the above methods increase the overall installation space and size of the servo motor, and the external filter is far away from the source of electromagnetic interference, which reduces the filtering effect. Utility Model Content

[0004] This utility model provides a servo motor, including: a motor housing, an inductor, an inner shielding cover, and a filter circuit board.

[0005] An inductor is provided inside the motor housing; an inner shield is provided inside the motor housing, the inner shield has a shielding cavity, and the inductor is provided inside the shielding cavity; a filter circuit board is provided inside the motor housing, and the filter circuit board is electrically connected to the inner shield.

[0006] As an implementation, the inductor includes a ring coil, and the shielding cavity surrounds at least circumferentially the ring coil.

[0007] As one possible implementation, the inner shielding cover includes a circumferentially closed portion and a planar portion. The circumferentially closed portion has a circumferentially closed shape, and the planar portion and the circumferentially closed portion form the shielding cavity. The filter circuit board is disposed within the shielding cavity. Alternatively,

[0008] The inner shielding cover includes a circumferentially unclosed portion and a planar portion. The circumferentially unclosed portion has an opening in its circumferentially unclosed shape. The filter circuit board is disposed at the opening and closes the opening. The planar portion, the circumferentially unclosed portion, and the filter circuit board constitute the shielding cavity.

[0009] As one possible implementation, the circumferentially closed portion, the circumferentially unclosed portion, and the planar portion are integrally formed, or...

[0010] The circumferentially enclosed portion, the circumferentially non-enclosed portion, and the planar portion are separately disposed, and the circumferentially enclosed portion, the circumferentially non-enclosed portion, and the planar portion are welded together at the splicing position.

[0011] As an alternative implementation, a drive circuit board is also included. The drive circuit board is located outside the shielding cavity, parallel to the planar portion, and is electrically connected to the inductor.

[0012] As an implementation method, the circumferentially closed portion or the circumferentially unclosed portion is provided with a first pin, the filter circuit board is provided with a first connector, the first pin is plugged into the first connector, and the two are soldered together; the planar portion is provided with a second pin, the drive circuit board is provided with a second connector, the second pin is plugged into the second connector, and the number of the first pins is greater than the number of the second pins.

[0013] As an alternative implementation, the drive circuit board is electrically connected to the motor housing, and the motor housing is grounded.

[0014] As an implementation method, the drive circuit board is provided with a noise device, the planar portion is projected onto the drive circuit board, and the noise device is located within the projection area of ​​the planar portion.

[0015] As an alternative implementation, the opening of the shielding cavity serves as a heat dissipation port, through which at least the inductor passes.

[0016] As an implementation method, the thickness t of the arc-shaped portion and the planar portion are equal, 0.4mm≤t≤0.8mm.

[0017] The above-described solution, by placing an inner shield inside the motor housing, helps to avoid altering the overall installation space and dimensions of the motor housing, thus preventing additional increases in motor production costs. Simultaneously, the inner shield and filter circuit board provide dual-stage suppression of inductor leakage, thereby suppressing electromagnetic interference generated within the servo motor and achieving excellent filtering performance. The combined structure of the filter circuit board and the circumferentially unclosed portion can surround the circumference of the ring coil, thereby suppressing most of the common-mode inductor leakage. The filter circuit board, the circumferentially unclosed portion, and the planar portion constitute the aforementioned shielding cavity, preventing electromagnetic interference generated by the bottom drive circuit and other circuits on both sides. The space of the shielding cavity is adapted to the common-mode inductor, facilitating miniaturization of the shielding cavity design; reducing the material usage of the inner shield to decrease production costs; providing a low grounding impedance path (inner shield → drive circuit board → motor housing → ground); the inner shield suppresses common-mode inductor magnetic leakage, preventing electromagnetic interference generated by the bottom drive circuit and other circuits on both sides, and shielding electromagnetic noise; the motor housing acts as a second layer of shielding, further shielding electromagnetic noise, while also blocking external electromagnetic noise interference to the common-mode inductor; the planar portion projects orthographically onto the drive circuit board, with noise-generating devices located within the projection area of ​​the planar portion. Covering the noise-generating device with a flat surface can block noise propagation, thereby suppressing noise. Attached Figure Description

[0018] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0019] Figure 1A schematic diagram of the structure of a servo motor provided in an embodiment of this utility model;

[0020] Figure 2 This is a schematic diagram of the connection between the inner shield and the filter circuit board provided in an embodiment of the present invention;

[0021] Figure 3 An exploded view showing the connection between the inner shield and the filter circuit board provided in an embodiment of this utility model;

[0022] Figure 4 This is a schematic diagram of the structure of the inner shielding cover provided in an embodiment of the present utility model;

[0023] Figure 5 The circuit diagram corresponding to the filter circuit board provided in the embodiment of this utility model;

[0024] Figure 6 Differential-mode and common-mode insertion loss curves provided for embodiments of this utility model;

[0025] Inductor 10, filter circuit board 20, first connector 21;

[0026] Inner shield 30, circumferential non-enclosed part 31, first pin 311, planar part 32, second pin 321, shielding cavity 301, opening 302;

[0027] Drive circuit board 40, motor housing 50. Detailed Implementation

[0028] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the relevant utility model and not intended to limit the scope of the utility model. Furthermore, it should be noted that, for ease of description, only the parts relevant to the utility model are shown in the accompanying drawings.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] This utility model provides a technical solution: such as Figures 1-5 As shown, the servo motor includes: a motor housing 50, a drive circuit board 40, an inductor 10, an inner shielding cover 30, and a filter circuit board 20. The motor housing 50 houses the inductor 10, the inner shielding cover 30, the drive circuit board 40, and the filter circuit board 20; the inner shielding cover 30 has a shielding cavity 301, and the inductor 10 is disposed within the shielding cavity 301; the filter circuit board 20 is electrically connected to the inner shielding cover 30.

[0031] The inductor 10 can be a differential-mode inductor or a common-mode inductor, and is electrically connected to the drive circuit board 40. The inductor 10 is connected to other components such as capacitors, resistors, and chips through conductive traces on the drive circuit board 40, forming circuits with specific functions such as filtering, energy storage, and voltage regulation. The drive circuit board 40 is located outside the shielded cavity 301.

[0032] The shielding cavity 301 can be cylindrical, recessed, or a closed cavity. The inner shielding cover 30 forms a shield for the inductor 10, suppressing electromagnetic wave leakage from the inductor 10, thereby suppressing electromagnetic interference from the cable and preventing electromagnetic interference generated by the bottom drive circuit and other circuits on both sides. The filter circuit board 20 can be disposed inside or outside the shielding cavity 301. The filter circuit board 20 is electrically connected to the inner shielding cover 30, and the connection point between the filter circuit board 20 and the shielding cover forms an eddy current loop, further absorbing residual leakage magnetic flux passing through the inner shielding cover 30. In this way, the inner shielding cover 30 and the filter circuit board 20 provide dual-stage suppression of leakage magnetic flux from the inductor 10.

[0033] In practical applications, the inductor 10 can be appropriately placed inside the shielding cavity 301. The inner shielding cover 30 is a metallic conductive shielding cover, including but not limited to those made of carbon steel, copper, aluminum, permalloy, and silicon steel. The thickness of the carbon steel material can be between 0.5 mm and 1 mm. It should be noted that the inner shielding cover 30 will not affect the arrangement of other components or parts inside the motor housing 50.

[0034] This application uses an inner shield 30 inside the motor housing 50, which helps to avoid changing the overall installation space and size of the motor housing 50, thereby avoiding additional motor production costs; at the same time, the inner shield 30 and the filter circuit board 20 suppress the leakage magnetic field of the inductor 10 in a dual-stage manner, resulting in good filtering effect.

[0035] The following embodiments use inductor 10 as a common-mode inductor for illustration:

[0036] The common-mode inductor includes a toroidal coil, and the shielding cavity 301 surrounds the toroidal coil at least circumferentially.

[0037] In a first specific embodiment, the inner shield 30 includes a circumferentially closed portion and a planar portion 32. The circumferentially closed portion has a circumferentially closed shape, for example, including but not limited to a rectangular cylinder, a triangular cylinder, a circular cylinder, and an elliptical cylinder. The circumferentially closed portion surrounds the circumference of the annular coil. The planar portion 32 and the circumferentially closed portion form the aforementioned shielding cavity 301. The space of the shielding cavity 301 is slightly larger than that of the common-mode inductor, so as to facilitate the placement of the filter circuit board 20 within the shielding cavity 301.

[0038] The circumferentially enclosed portion adopts a circumferentially closed design, which can suppress most of the leakage flux of the common-mode inductor and shield electromagnetic noise. The planar portion 32 can further improve the leakage flux suppression rate of the common-mode inductor and enhance the electromagnetic noise shielding effect.

[0039] In some embodiments, the circumferentially closed portion and the planar portion 32 can be formed by stamping or 3D printing, and no gaps will be formed at the contact point between the circumferentially closed portion and the planar portion 32, which helps the inner shield 30 suppress electromagnetic leakage of the inductor 10. In other embodiments, the circumferentially closed portion and the planar portion 32 are separately provided, and the two are welded together at the splicing point, so that no gaps will be formed at the splicing point between the circumferentially closed portion and the planar portion 32, which helps the inner shield 30 suppress electromagnetic leakage of the inductor 10.

[0040] In the second specific embodiment, such as Figures 2-4 As shown, the inner shield 30 includes a circumferentially unclosed portion 31 and a planar portion 32. The circumferentially unclosed portion 31 has a circumferentially unclosed shape, such as, but not limited to, a U-shape, a V-shape, a semi-circle, or a semi-ellipse. Because the circumferentially unclosed portion 31 is circumferentially unclosed, it has an opening 302, which corresponds to the planar portion 32. This allows the filter circuit board 20 to close the opening 302, so that the combined structure of the filter circuit board 20 and the circumferentially unclosed portion 31 can surround the circumference of the annular coil, thereby suppressing most of the leakage flux of the common-mode inductor.

[0041] The filter circuit board 20, the circumferentially unclosed portion 31, and the planar portion 32 constitute the shielding cavity 301. The space of the shielding cavity 301 is adapted to the common mode inductor. Compared with the shielding cavity 301 in the first embodiment, the shielding cavity 301 in this embodiment has a smaller space, which helps to miniaturize the shielding cavity 301. At the same time, it reduces the material used in the inner shielding cover 30, thereby reducing production costs.

[0042] It should be noted that the opening in the shielding cavity 301 can serve as a heat dissipation vent, allowing the common-mode inductor's heat to be transferred to the external environment. The size of the heat dissipation vent can be larger than the size of the inductor 10, or the heat dissipation vent can be such that the inductor 10 passes through it, which helps with the heat dissipation of the common-mode inductor.

[0043] In some embodiments, the circumferentially unclosed portion 31 and the planar portion 32 can be formed by stamping or 3D printing, among other things. This ensures that there are no gaps at the contact points between the circumferentially unclosed portion 31 and the planar portion 32, which helps the inner shielding cover 30 suppress electromagnetic leakage of the inductor 10. In other embodiments, the circumferentially unclosed portion 31 and the planar portion 32 are separately disposed, and their joint is welded together. This ensures that there are no gaps at the joint points between the circumferentially unclosed portion 31 and the planar portion 32, which also helps the inner shielding cover 30 suppress electromagnetic leakage of the inductor 10.

[0044] Furthermore, the drive circuit board 40 is arranged parallel to the planar portion 32, and the drive circuit board 40 and the filter circuit board 20 can be arranged at 90°, or approximately 90°. This arrangement can reduce the overall size of the drive circuit board 40, the inductor 10, and the inner shielding cover 30.

[0045] like Figure 4 As shown, the inner shielding cover 30 includes a circumferentially unclosed portion 31 and a planar portion 32. The circumferentially unclosed portion 31 is a U-shaped cover, and a filter circuit board 20 is provided at the opening 302 of the U-shaped cover. The filter circuit board 20 closes the opening 302. The planar portion 32, the filter circuit board 20, and the U-shaped cover form the aforementioned shielding cavity 301.

[0046] like Figure 3 As shown, the edge of the opening 302 of the U-shaped cover is provided with multiple first pins 311. Correspondingly, the filter circuit board 20 is provided with a first connector 21 adapted to the first pins 311, and the first connector 21 corresponds one-to-one with the first pins 311. The first pins 311 are inserted into the first connectors 21, and the two are soldered together to realize the electrical connection between the U-shaped cover and the filter circuit board 20. Considering that the servo motor is used in a vibration scenario, the connection method between the U-shaped cover and the filter circuit board 20 can ensure the stability of the connection.

[0047] like Figure 2 As shown, the planar portion 32 has multiple second pins 321. Correspondingly, the drive circuit board 40 has a second connector adapted to the second pins 321, with each second connector corresponding to one of the second pins 321. The second pins 321 are plugged into the second connectors, and the two are soldered together. The drive circuit board 40 is electrically connected to the motor housing 50 via an electrical connection wire, and the motor housing 50 is grounded. The drive circuit board 40 is directly soldered to the planar portion 32 to achieve a low-impedance connection, thereby providing a low grounding impedance path (inner shield 30 → drive circuit board 40 → motor housing 50 → ground). The inner shield 30 suppresses common-mode inductor magnetic leakage and shields electromagnetic noise. The motor housing 50, as a second layer of shielding, further shields electromagnetic noise and blocks external electromagnetic noise interference to the common-mode inductor.

[0048] The number of first pins 311 is greater than the number of second pins 321. It should be noted that the inner shield 30 is used to suppress most of the leakage magnetic flux of the common mode inductor, so it is necessary to ensure the connection strength between the inner shield 30 and the filter circuit board 20, which requires that the number of first pins 311 be greater than the number of second pins 321.

[0049] In practical applications, noise-generating devices, such as MOSFETs, IGBT switching devices, and driver chips, can be provided on the surface of the drive circuit board 40 facing the planar portion 32.

[0050] To suppress the aforementioned noise, refer to Figure 1 As shown, the planar portion 32 is projected orthographically onto the drive circuit board 40, and the noise device is located within the projection area of ​​the planar portion 32. The planar portion 32 covers the noise device, which can block noise propagation and thus suppress noise.

[0051] The thickness t of the arc-shaped part and the flat part 32 is the same, 0.4mm≤t≤0.8mm.

[0052] It should be noted that, considering the application scenarios of servo motors, including vibration scenarios, the inner shield 30 needs to have good stability, rigidity and strength, and needs to withstand vibration or impact; at the same time, to avoid excessive production costs of the inner shield 30, the thickness t of the circumferential closed part, the circumferential non-closed part 31 and the planar part 32 can be limited to be equal, 0.4mm≤t≤0.8mm.

[0053] Among them, the filter circuit board 20, such as Figure 5 As shown, a first-stage common-mode filter is composed of common-mode capacitors CY1-CY6 and common-mode inductor L1, as follows: Figure 6 As shown, this filter combination achieves 80dB differential mode insertion loss (DM) and 40dB common mode insertion loss (CM) in the 100kHz-5MHz frequency band; 140dB differential mode insertion loss (DM) and 80dB common mode insertion loss (CM) in the 1MHz-10MHz band; and 60dB differential mode insertion loss (DM) and 80dB common mode insertion loss (CM) in the 10MHz-50MHz band.

[0054] Among them, the differential mode capacitors CX1-CX4 can be selected with capacitance values ​​of 0.1uF, 0.68uF, 1uF, 2.2uF, and 10uF, the common mode capacitors CY1-CY6 can be selected with capacitance values ​​of 2.2nF, 4.7nF, 10nF, 22nF, and 47nF, and the common mode inductor L1 can be selected with an inductance of 1-3mH.

[0055] Of course, it is understood that the filter circuit board 20 may include, but is not limited to, differential mode capacitors CX1-CX4 and common mode inductor L1, and may also be composed of other components. Those skilled in the art can choose according to the actual situation, and this embodiment does not limit this.

[0056] It should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" used above to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0057] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the utility model involved in this application is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A servo motor, characterized in that, include: Motor housing (50), wherein an inductor (10) is provided inside the motor housing (50); An inner shield (30) is disposed inside the motor housing (50), the inner shield (30) is provided with a shielding cavity (301), and the inductor (10) is disposed inside the shielding cavity (301); A filter circuit board (20) is disposed inside the motor housing (50), and the filter circuit board (20) is electrically connected to the inner shield (30).

2. The servo motor according to claim 1, characterized in that, The inductor (10) includes a ring coil, and the shielding cavity (301) surrounds the ring coil at least circumferentially.

3. The servo motor according to claim 2, characterized in that, The inner shield (30) includes a circumferentially closed portion and a planar portion (32). The circumferentially closed portion is circumferentially closed in shape. The planar portion (32) and the circumferentially closed portion form the shielding cavity (301). The filter circuit board (20) is disposed inside the shielding cavity (301). The inner shield (30) includes a circumferentially unclosed part (31) and a planar part (32). The circumferentially unclosed part (31) has an opening (302) in a circumferentially unclosed shape. The filter circuit board (20) is disposed at the opening (302) and closes the opening (302). The planar part (32), the circumferentially unclosed part (31) and the filter circuit board (20) constitute the shielding cavity (301).

4. The servo motor according to claim 3, characterized in that, The circumferentially closed portion, the circumferentially unclosed portion (31), and the planar portion (32) are integrally formed, or, The circumferential closed part, the circumferential non-closed part (31) and the planar part (32) are separately provided, and the circumferential closed part, the circumferential non-closed part (31) and the planar part (32) are welded together at the splicing position.

5. The servo motor according to claim 3, characterized in that, It also includes a driver circuit board (40). The drive circuit board (40) is located outside the shielding cavity (301) and is arranged parallel to the planar part (32). The drive circuit board (40) is electrically connected to the inductor (10).

6. The servo motor according to claim 5, characterized in that, The circumferential closed portion or the circumferential non-closed portion (31) is provided with a first pin (311), the filter circuit board (20) is provided with a first connector (21), the first pin (311) is plugged into the first connector (21), and the two are soldered together; the planar portion (32) is provided with a second pin (321), the drive circuit board (40) is provided with a second connector, the second pin (321) is plugged into the second connector, and the number of the first pin (311) is greater than the number of the second pin (321).

7. The servo motor according to claim 6, characterized in that, The drive circuit board (40) is electrically connected to the motor housing (50), and the motor housing (50) is grounded.

8. The servo motor according to claim 5, characterized in that, The drive circuit board (40) is provided with a noise device, the planar part (32) is projected onto the drive circuit board (40), and the noise device is located in the projection area of ​​the planar part (32).

9. The servo motor according to any one of claims 3-8, characterized in that, The opening of the shielding cavity (301) serves as a heat dissipation port, through which at least the inductor (10) passes.

10. The servo motor according to any one of claims 3-8, characterized in that, The thickness t of the circumferential closed part, the circumferential non-closed part (31) and the planar part (32) are all equal, 0.4mm≤t≤0.8mm.

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