Low-altitude aircraft eddy current sensor and manufacturing method thereof
By dividing the PCBA board of the low-altitude aircraft eddy current sensor into upper and lower layers and using thermal riveting and adhesive curing methods, the problems of large sensor size, weight, and high cost are solved, achieving lightweighting and miniaturization, making it suitable for high-temperature environments, and improving measurement accuracy and dynamic response capabilities.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-04-03
AI Technical Summary
Existing position sensors for low-altitude aircraft motors, such as resolvers, are bulky, heavy, costly, sensitive to mechanical misalignment, and difficult to implement in a compact and redundant system. Eddy current sensors lack mature solutions for large-scale spatial deployment.
A low-altitude aircraft eddy current sensor is designed, which adopts a PCBA board mounted on a bracket with an upper and lower layer structure. The upper and lower boards are respectively installed on the upper and lower sides of the bracket. The eddy current induction coil is arranged on the lower board, and the chip and other components are arranged on the upper board. The fixation is achieved by hot riveting and adhesive curing.
This technology enables the sensor to be lightweight, cost-reduced, and miniaturized, making it suitable for high-temperature environments. It also improves measurement accuracy and dynamic response capabilities, simplifies processing and assembly procedures, and reduces manufacturing costs.
Smart Images
Figure CN121793231A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of motor control technology, and specifically relates to an eddy current sensor for low-altitude aircraft and its manufacturing method. Background Technology
[0002] In existing technologies, position sensors are key components for achieving precise and efficient control in high-power-density motors—the driving heart of low-altitude aircraft (such as drones and eVTOL flying cars). Like the "nerve endings" of the motor, they report the precise angle and speed of the rotor to the controller in real time, enabling complex vector control and precise commutation. Resolver sensors are currently the mainstream solution for motor position detection in low-altitude aircraft. However, they have inherent drawbacks such as large size and weight, high cost, sensitivity to mechanical misalignment, and difficulty in achieving truly compact redundancy. While eddy current sensors offer advantages such as high resolution and high bandwidth, there is currently no mature solution for applying them to motor angle measurement and designing a dual-redundant system that meets the safety and large-size (sensor diameter greater than or equal to 180mm) space requirements for low-altitude aircraft.
[0003] I. Traditional Mainstay: Resolver Sensor A resolver sensor is an absolute position sensor based on the principle of electromagnetic induction, and is known for its high reliability and stability in harsh environments.
[0004] 1. Core Structure and Working Principle The structure of a resolver is similar to that of a miniature electric motor, consisting of a stator and a rotor: Stator: It has one set of excitation windings and two sets of sine and cosine output windings arranged at a 90-degree electrical angle in space.
[0005] Rotor: Employs a salient pole structure with an excitation winding (traditional brushed type) or a specially shaped metal magnetic ring (modern brushless type). Brushless resolvers achieve contactless energy coupling through an additional transformer stator.
[0006] Principle: The resolver operates like a rotating transformer. The controller applies a high-frequency sinusoidal AC reference signal to the excitation winding. This signal is transmitted to the rotor via electromagnetic coupling. As the rotor rotates, its salient pole structure modulates the magnetic field, inducing voltage signals on the stator's sine and cosine windings whose amplitude varies with the rotor angle (θ) as sine and cosine. Finally, a dedicated decoding chip calculates the absolute angle θ from these two signals through mathematical operations (such as arctangent).
[0007] 2. Inherent defects and structural root causes Despite their excellent performance, the inherent mechanical and electromagnetic structure of resolvers also presents a series of problems: Large size and weight, high cost: Its multi-winding, laminated iron core structure makes it difficult to miniaturize and lighten, and the complex manufacturing process and dedicated decoding chip also increase the system cost.
[0008] Low-to-medium speed performance and bandwidth limitations: As a "passive" modulated sensor, its dynamic response is limited by the excitation frequency. Increasing the frequency will lead to core loss and heat generation issues.
[0009] Sensitive to mechanical misalignment: Its accuracy depends on the perfect symmetry of the air gap magnetic field between the stator and rotor. Any radial or axial installation misalignment will disrupt the magnetic field symmetry, causing output waveform distortion and introducing measurement errors.
[0010] High-temperature performance faces challenges: the change in winding resistance with temperature and the potential performance degradation of the core material at high temperatures limit its application in extreme high-temperature environments.
[0011] II. Emerging Powerhouse: Advantages of Eddy Current Sensors An eddy current sensor is a non-contact sensor that detects displacement by measuring changes in the eddy current effect on a conductor surface. A sensor measuring the angular position of eddy currents in a motor can be divided into two main parts: the stator and the target section (rotor). The stator uses PCB coil windings, which are divided into an excitation section and an induction section (sine and cosine). The excitation section, together with capacitors in the circuit, forms an oscillator circuit. The oscillator generates a magnetic field of a specific intensity around the excitation section, which is coupled to the sine and cosine induction sections through mutual inductance. When a conductive target (rotor) passes through the coil, eddy currents are formed on the conductor surface. As the angle of the target position (rotor) changes, this results in changes in the sine and cosine induced voltages. The generated sine and cosine voltages are related to the unique electrical angle that can be obtained, thus calculating the angular position. The induction section is insensitive to radial runout and can even simultaneously detect the radial displacement of the shaft.
[0012] Compared with resolvers, eddy current sensors have the following significant advantages: Extremely high resolution: Directly measures the angular position of the motor, with a mechanical accuracy of up to 0.01°. In addition, the dynamic response speed of analog signals far exceeds that of resolvers, meeting the requirements of ultra-high speed and extremely fast response control.
[0013] Small size and lightweight: The wiring of the sensor is thin and small, which greatly saves the aircraft's precious space and weight budget.
[0014] Its revolutionary advantage lies in its insensitivity to misalignment and its diagnostic capabilities. Not only is it unaffected by radial runout, but it also provides simultaneous diagnostic information on shaft vibration and eccentricity, enabling predictive maintenance.
[0015] Robust and durable with excellent high-temperature performance: The sensing element is entirely solid-state or glue-encapsulated, with no easily damaged parts, and has strong resistance to shock and vibration. Furthermore, it uses transmission fluid-resistant and high-temperature-resistant materials, enabling stable operation in an oil-cooled environment of 150°C.
[0016] III. Summary and Comparison Resolver sensors, as a mature and reliable technology, have played a crucial role in numerous motor drive applications, both past and present. However, sensors for next-generation low-altitude aircraft often require ultra-low power consumption, ultra-high dynamic performance, and high integration and intelligence. Eddy current sensor technology, with its comprehensive advantages of high precision, high response, multi-functional diagnostics, and lightweight design, is becoming an increasingly attractive technological direction. It is not merely a simple position feedback element, but a key step towards intelligent motor condition monitoring, representing the future development trend of sensor technology for aircraft drive systems. Summary of the Invention
[0017] The purpose of this invention is to provide an eddy current sensor for low-altitude aircraft that is suitable for low-altitude aircraft applications and has the advantages of being lightweight, reducing weight, size, and cost.
[0018] One of the objectives of this invention is achieved as follows: a low-altitude aircraft eddy current sensor includes a bracket on which a PCBA board is mounted. The bracket is annular and has several positioning frames on its upper side. The PCBA board includes an upper plate and a lower plate. The upper plate is mounted on each positioning frame, and the lower plate is mounted on the lower side of the bracket. A connecting part is provided between the upper plate and the lower plate.
[0019] As a further improvement of the present invention, the upper plate is arc-shaped, and the lower plate is annular. The annular lower plate is coaxially arranged with the support, and the radial width of the upper plate is greater than that of the lower plate. Both the upper and lower plates are four-layer structures, each including two outer PCBA rigid boards. Two layers of bonded PCBA flexible boards are disposed between the two outer PCBA rigid boards. The connecting part is composed of two bonded PCBA flexible boards. The two layers of PCBA flexible boards in the connecting part, the two layers of PCBA flexible boards in the upper plate, and the two layers of PCBA flexible boards in the lower plate are all the same two layers of PCBA flexible boards. The PCBA is made of a rigid-flex board. The upper and lower boards are rigid boards with a total of four layers, consisting of two rigid layers sandwiching two flexible layers. The connecting part between the upper and lower boards is a flexible board with a total of two layers.
[0020] As a further improvement of the present invention, two circumferentially spaced side positioning frames are provided on the upper side of the bracket, and a middle positioning frame is provided on the bracket between the two side positioning frames. The circumferential distance between the middle positioning frame and the two side positioning frames is equal. A support pad is provided on the bracket between each middle positioning frame and a side positioning frame. The upper plate is supported by the middle positioning frame, the side positioning frame, and the support pad.
[0021] As a further improvement of the present invention, the side positioning frame includes an inner support column and two outer reinforcing columns, which are arranged radially correspondingly. Both the inner support column and the outer reinforcing columns are hollow columns, and the height of the outer reinforcing columns is higher than that of the inner support column. An outer reinforcing plate is provided between the two outer reinforcing columns. A side support plate is provided between the inner support column and each outer reinforcing column, and the side support plate is set at the same height as the inner support column. Each side support plate is provided with a limiting plate integrally connected to the corresponding outer reinforcing column. The length of the limiting plate is less than the length of the side support plate, and an assembly groove is provided on the limiting plate. A gap is left between the assembly slot and the side support plate. The outer reinforcing plate, two outer reinforcing columns, and two limiting plates form an open isosceles trapezoidal limiting slot. A through connection hole is provided on the bracket below each outer reinforcing column. The central positioning frame includes two radially corresponding central support columns. A left support plate and a right support plate are respectively provided on the left and right sides of the two central support columns. Both the left and right support plates are open trapezoidal in shape and have several PCBA board connection holes. A through connection hole is provided on the bracket below each central support column. The sensor is assembled through the assembly slot.
[0022] As a further improvement of the present invention, the upper plate is supported on a left support plate, a right support plate, a side support plate, an inner support column, and a support pad of equal height. The radial width of the upper plate corresponds to the radial width of the bracket. Two clearance grooves are provided on the upper plate corresponding to the two middle support columns. Several PCBA board connection holes are provided on the upper plate corresponding to the PCBA board connection holes on the left and right support plates. Several fastening bolts with adhesive pass downward through the corresponding PCBA board connection holes on the upper plate and are inserted into the corresponding PCBA board connection holes on the left or right support plates. The upper plate is fixed to the middle positioning frame. A mating groove is provided on both the left and right sides of the upper plate corresponding to each limiting plate. The left and right edges of the upper plate fit into the corresponding limiting grooves. A wire harness is connected to the upper plate. The limiting grooves limit the upper plate, and the PCBA board connection holes are used to install and fix the upper plate.
[0023] As a further improvement of the present invention, an annular mounting groove is provided on the lower side of the bracket. The annular mounting groove is coaxially arranged with the bracket. The depth of the mounting groove is less than the thickness of the bracket. Several circumferentially distributed protruding positioning parts are provided on the inner circumference of the annular lower plate. The lower plate and each protruding positioning part are correspondingly matched and embedded in the mounting groove. Each protruding positioning part is hot-riveted to the bracket. A bypass groove is provided on the outer peripheral edge of the annular bracket corresponding to the connecting part. The connecting part passes through the bypass groove upward. The thickness of the lower plate is less than the depth of the mounting groove. Epoxy adhesive is also injected into the mounting groove to seal the lower plate.
[0024] As a further improvement of the present invention, the bracket is further provided with several sets of through-connecting holes II distributed at intervals along the arc direction. Each set of through-connecting holes II includes two through-connecting holes II distributed at intervals along the radial direction. Each through-connecting hole II is staggered from the upper plate. Multiple fasteners pass through each through-connecting hole I and through-connecting hole II to fix the bracket to the motor housing. The bracket is provided with two positioning pin holes spaced 180° apart circumferentially. The two positioning pin holes are a round hole and an oblong hole, respectively. The positioning pin holes, one round hole and one oblong hole, mate with the positioning pins on the motor housing.
[0025] As a further improvement of the present invention, the eddy current induction coil is arranged on the lower plate, and the chip and other components are arranged on the upper plate. The area where the chip and other components are arranged is offset from the upward vertical projection area of the lower plate on the upper plate. The upper plate has a larger radial width than the lower plate, and the area where the chip and other components are arranged is outside the vertical projection area of the lower plate on the upper plate, so as to reduce interference with the signal.
[0026] The second objective of this invention is achieved as follows: a method for manufacturing an eddy current sensor for a low-altitude aircraft, comprising the following steps: (1) Insert the lower plate of the PCBA board into the mounting groove on the lower side of the bracket, and fix the lower plate and the bracket by heat riveting; (2) Pour epoxy glue into the mounting groove of the bracket to cure and fix the lower plate; (3) Fold the upper plate of the PCBA board onto the upper side of the bracket. The connecting part of the PCBA board passes through the bypass groove, so that the left and right edges of the upper plate are respectively fitted into the limiting grooves of the two side positioning frames. The upper plate is supported on the left support plate, right support plate, side support plate, inner support column and support pad of equal height. (4) Insert several fastening bolts with glue downward through the corresponding PCBA board connection holes on the upper plate and into the corresponding PCBA board connection holes on the left or right support plate to fix the upper plate to the bracket.
[0027] The eddy current stator structure for low-altitude aircraft of this invention consists of three main parts: a PCBA, a support frame, and a wiring harness. The PCBA is made of a rigid-flex board; the upper and lower boards are rigid boards, with a total of four layers: two rigid layers sandwiching two flexible layers. The connecting part between the upper and lower boards is a flexible board, with two flexible layers. The eddy current induction coil is arranged on the lower board, and the chip and other components are arranged on the upper board. The upper board is larger than the lower board, and the area where the chip and other components are arranged is outside the vertical projection area of the lower board onto the upper board to reduce signal interference. The support frame is located between the two boards. During installation, the coil board is first installed in the support frame and fixed by heat riveting, then epoxy adhesive is applied and cured. The upper board is then folded to the other side of the support frame and secured by a limiting clip. Mounting holes are pre-drilled in the support frame; bolts with adhesive are pressed into the mounting holes, and the adhesive is cured to achieve a fixed effect.
[0028] Compared with existing technologies, the advantages of this invention are as follows: By dividing the PCBA board into two layers, an upper plate and a lower plate, and mounting the upper and lower plates on the upper and lower sides of the bracket respectively, the radial width of the PCBA board can be reduced, resulting in lighter weight, space savings, and lower costs. This makes it suitable for lightweight applications such as low-altitude aircraft. The eddy current induction coil is arranged on the lower plate, while the chip and other components are arranged on the upper plate. The upper plate has a larger radial width than the lower plate, and the area where the chip and other components are arranged is outside the vertical projection area of the lower plate onto the upper plate, thereby reducing interference with the signal. The low-altitude aircraft eddy current sensor of this invention is a stator, which works in conjunction with a rotor.
[0029] The present invention has the following advantages: (1) Existing eddy current sensors have high requirements for radial arrangement space and large radial clearance space. (2) Lightweight problem: solves the problem of large volume and weight of resolvers and high cost; achieves miniaturization and lightweighting, reducing costs. (3) Unaffected by rotational speed performance and bandwidth. (4) High measurement accuracy. (5) Suitable for applications in high temperature environments.
[0030] This invention significantly simplifies the processing and assembly process, saves raw materials, improves production efficiency, and reduces manufacturing costs. It uses standardized micro probes and simple metal target wheels, eliminating most of the precious metals and complex processes. It is easy to control: for motor manufacturers, only a simple target wheel needs to be installed, instead of precisely aligning and installing a bulky integral component like a resolver, making processing, operation, control, and use much simpler. Attached Figure Description
[0031] Figure 1 This is a three-dimensional structural diagram of the present invention.
[0032] Figure 2 This is a three-dimensional structural diagram of the present invention.
[0033] Figure 3 This is a schematic diagram of the support structure.
[0034] Figure 4 for Figure 3 A magnified view of a portion of the image.
[0035] Figure 5 This is an enlarged view of the side positioning frame.
[0036] Figure 6 This is a schematic diagram of the PCBA board structure.
[0037] Figure 7 This is a structural diagram of a PCBA board.
[0038] Figure 8 This is a schematic diagram of the structure at the bottom of the support.
[0039] Figure 9 A schematic diagram of the structure of the lower plate inside the mounting slot of the bracket.
[0040] Figure 10 This is a bottom view of the support frame.
[0041] The components include: 1. PCBA board, 1a. upper board, 1b. lower board, 1b1. protruding positioning part, 1c. connecting part, 101. PCBA rigid board, 102. PCBA flexible board, 2. bracket, 3. side positioning frame, 301. inner support column, 302. outer reinforcing column, 303. outer reinforcing plate, 304. side support plate, 305. limiting plate, 4. middle positioning frame, 5. support pad, 6. assembly groove, 7. limiting groove, 8. through connection hole one, 9. middle support column, 10. left support plate, 11. right support plate, 12. PCBA board connection hole, 13. clearance groove, 14. mating groove, 15. wire harness, 16. mounting groove, 17. bypass groove, 18. epoxy adhesive, 19. through connection hole two, 20. positioning pin hole. Detailed Implementation
[0042] like Figure 1-10 As shown, a low-altitude aircraft eddy current sensor includes a bracket 2, on which a PCBA board 1 is mounted. The bracket 2 is annular, and several positioning frames are provided on the upper side of the bracket 2. The PCBA board 1 includes an upper plate 1a and a lower plate 1b. The upper plate 1a is mounted on each positioning frame, and the lower plate 1b is mounted on the lower side of the bracket 2. A connecting part 1c is provided between the upper plate 1a and the lower plate 1b. The upper plate 1a is arc-shaped, and the lower plate 1b is annular. The annular lower plate 1b is coaxially arranged with the bracket 2. The radial width of the upper plate 1a is greater than that of the lower plate 1b. Both the upper plate 1a and the lower plate 1b are four-layer structures. Both the upper plate 1a and the lower plate 1b include two outer rigid PCBA boards 101. Two layers of bonded PCBA flexible boards 102 are arranged between the two outer rigid PCBA boards 101. The connecting part 1c is two layers of bonded PCBA flexible boards 102. The two layers of PCBA flexible boards 102 in the connecting part 1c, the two layers of PCBA flexible boards 102 in the upper plate 1a, and the two layers of PCBA flexible boards 102 in the lower plate 1b are the same two layers of PCBA flexible boards 102. The PCBA is made of rigid-flex boards. The upper and lower boards are rigid boards with a total of four layers, with two rigid layers sandwiching two flexible layers. The part connecting the upper and lower boards is a flexible board with a total of two layers.
[0043] The support 2 has two circumferentially spaced side positioning frames 3 on its upper side. A middle positioning frame 4 is located between the two side positioning frames 3 on the support 2, and the circumferential distance between the middle positioning frame 4 and the two side positioning frames 3 is equal. A support pad 5 is provided on the support 2 between each middle positioning frame 4 and a side positioning frame 3. The upper plate 1a is supported by the middle positioning frame 4, the side positioning frame 3, and the support pad 5. The side positioning frame 3 includes an inner support column 301 and two outer reinforcing columns 302, which are arranged radially correspondingly. Both the inner support column 301 and the outer reinforcing columns 302 are hollow columns. The height of the outer reinforcing columns 302 is higher than that of the inner support column 301. An outer reinforcing plate 303 is provided between the two outer reinforcing columns 302. A side support plate 304 is provided between the inner support column 301 and each outer reinforcing column 302. The side support plate 304 is set at the same height as the inner support column 301. Each side support plate 304 is provided with a limiting plate 305 that is integrally connected with the corresponding outer reinforcing column 302. The length of the limiting plate 305 is less than the length of the side support plate 304. The limiting plate 305 has a [missing information]. Assembly slot 6 has a gap between it and side support plate 304. Outer reinforcing plate 303, two outer reinforcing columns 302, and two limiting plates 305 form an open isosceles trapezoidal limiting slot 7. A through-hole 8 is provided on bracket 2 below each outer reinforcing column 302. The central positioning frame 4 includes two radially corresponding central support columns 9. A left support plate 10 and a right support plate 11 are respectively provided on the left and right sides of the two central support columns 9. Both the left and right support plates 10 and 11 are open trapezoidal in shape and have several PCBA board connection holes 12. A through-hole 8 is provided on bracket 2 below each central support column 9. The sensor is assembled through assembly slot 6.
[0044] The upper plate 1a is supported on the left support plate 10, right support plate 11, side support plate 304, inner support column 301, and support pad 5 of equal height. The radial width of the upper plate 1a corresponds to the radial width of the bracket 2. Two clearance grooves 13 are opened on the upper plate 1a corresponding to the two middle support columns 9. Several PCBA board connection holes 12 are opened on the upper plate 1a corresponding to the PCBA board connection holes 12 on the left support plate 10 and right support plate 11. Several fastening bolts with glue pass downward through the corresponding PCBA board connection holes 12 of the upper plate 1a and are inserted into the corresponding PCBA board connection holes 12 on the left support plate 10 or right support plate 11. The upper plate 1a is fixed to the middle positioning frame 4. A mating groove 14 is opened on both the left and right sides of the upper plate 1a corresponding to each limiting plate 305. The left and right edges of the upper plate 1a fit into the corresponding limiting grooves 7. A wire harness 15 is connected to the upper plate 1a. The limiting groove 7 limits the upper plate 1a, and the PCBA board connection hole 12 is used to install and fix the upper plate 1a.
[0045] The bracket 2 has an annular mounting groove 16 on its lower side. The annular mounting groove 16 is coaxially arranged with the bracket 2. The depth of the mounting groove 16 is less than the thickness of the bracket 2. The inner circumference of the annular lower plate 1b has several circumferentially distributed protruding positioning parts 1b1. The lower plate 1b and each protruding positioning part 1b1 are correspondingly matched with the mounting groove 16 and embedded in the mounting groove 16. Each protruding positioning part 1b1 is hot-riveted to the bracket 2. The outer circumferential edge of the annular bracket 2 has a bypass groove 17 corresponding to the connecting part 1c. The connecting part 1c passes upward through the bypass groove 17. The thickness of the lower plate 1b is less than the depth of the mounting groove 16. The mounting groove 16 is also filled with epoxy glue 18 to seal the lower plate 1b.
[0046] The bracket 2 is also provided with several sets of through-connecting holes 19 spaced apart along the arc direction. Each set of through-connecting holes 19 includes two through-connecting holes 19 spaced apart radially. Each through-connecting hole 19 is staggered from the upper plate 1a. Multiple fasteners pass through each through-connecting hole 18 and through-connecting hole 19 to fix the bracket 2 to the motor housing. The bracket 2 is provided with two positioning pin holes 20 spaced 180° apart circumferentially. The two positioning pin holes 20 are a round hole and an oblong hole, respectively. The positioning pin holes 20, one round hole and one oblong hole, mate with the positioning pins on the motor housing.
[0047] The eddy current induction coil is arranged on the lower plate 1b, and the chip and other components are arranged on the upper plate 1a. The area where the chip and other components are arranged is offset from the area of the lower plate 1b projected vertically upwards onto the upper plate 1a. The upper plate 1a has a larger radial width than the lower plate 1b, and the area where the chip and other components are arranged is outside the area of the lower plate 1b projected vertically onto the upper plate 1a, in order to reduce interference with the signal.
[0048] The present invention discloses a method for manufacturing an eddy current sensor for a low-altitude aircraft, comprising the following steps: (1) Insert the lower plate 1b of the PCBA board into the mounting groove 16 on the lower side of the bracket 2, and fix the lower plate 1b and the bracket 2 by heat riveting. (2) Pour epoxy glue 18 into the mounting groove 16 of bracket 2 to cure and fix the lower plate 1b; (3) Fold the upper plate 1a of the PCBA board onto the upper side of the bracket 2. The connecting part 1c of the PCBA board passes through the bypass groove 17, so that the left and right edges of the upper plate 1a are respectively fitted into the limiting grooves 7 of the two side positioning frames 3. The upper plate 1a is supported on the left support plate 10, right support plate 11, side support plate 304, inner support column 301 and support pad 5 of the same height. (4) Insert several fastening bolts with glue downward through the corresponding PCBA board connection holes 12 of the upper plate 1a and into the corresponding PCBA board connection holes 12 on the left support plate 10 or the right support plate 11 to fix the upper plate 1a to the bracket 2.
[0049] The eddy current stator structure for low-altitude aircraft of this invention consists of three main parts: a PCBA, a support 2, and a wiring harness 15. The PCBA is made of a rigid-flex board; the upper and lower boards are rigid boards, with a total of four layers, consisting of two rigid layers sandwiching two flexible layers; the connecting part between the upper and lower boards is a flexible board, with two flexible layers. The eddy current induction coil is arranged on the lower board 1b, and the chip and other components are arranged on the upper board 1a. The upper board 1a is larger than the lower board 1b, and the area where the chip and other components are arranged is outside the vertical projection area of the lower board 1b onto the upper board 1a, to reduce signal interference. The support 2 is located between the two boards. During installation, the coil board is first installed inside the support 2, fixed by heat riveting, and then cured with epoxy glue 18. The upper board 1a is then folded to the other side of the support 2 and secured to the support 2 by a limiting clip. Mounting holes are pre-drilled on the support 2; bolts with glue are pressed into the mounting holes, and the glue is then cured to achieve a fixing effect.
[0050] This invention divides the PCBA board into two layers, an upper plate 1a and a lower plate 1b, which are respectively mounted on the upper and lower sides of a bracket 2. This reduces the radial width of the PCBA board, thereby reducing weight, saving space, and lowering costs. It is suitable for lightweight applications such as low-altitude aircraft. The eddy current induction coil is arranged on the lower plate 1b, while the chip and other components are arranged on the upper plate 1a. The upper plate 1a has a larger radial width than the lower plate 1b, and the area where the chip and other components are arranged is outside the vertical projection area of the lower plate 1b onto the upper plate 1a, thus reducing signal interference. The low-altitude aircraft eddy current sensor of this invention is a stator, which works in conjunction with a rotor.
[0051] The present invention has the following advantages: (1) Existing eddy current sensors have high requirements for radial arrangement space and large radial clearance space. (2) Lightweight problem: solves the problem of large volume and weight of resolvers and high cost; achieves miniaturization and lightweighting, reducing costs. (3) Unaffected by rotational speed performance and bandwidth. (4) High measurement accuracy. (5) Suitable for applications in high temperature environments.
[0052] This invention significantly simplifies the processing and assembly process, saves raw materials, improves production efficiency, and reduces manufacturing costs. It uses standardized micro probes and simple metal target wheels, eliminating most of the precious metals and complex processes. It is easy to control: for motor manufacturers, only a simple target wheel needs to be installed, instead of precisely aligning and installing a bulky integral component like a resolver, making processing, operation, control, and use much simpler.
[0053] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.
Claims
1. A low-altitude aircraft eddy current sensor, comprising a bracket on which a PCBA board is mounted, characterized in that, The bracket is ring-shaped, and several positioning frames are provided on the upper side of the bracket. The PCBA board includes an upper plate and a lower plate. The upper plate is installed on each positioning frame, and the lower plate is installed on the lower side of the bracket. A connecting part is provided between the upper plate and the lower plate.
2. The eddy current sensor for low-altitude aircraft according to claim 1, characterized in that, The upper plate is arc-shaped, and the lower plate is annular. The annular lower plate is coaxially arranged with the support. The radial width of the upper plate is greater than that of the lower plate. Both the upper and lower plates are four-layer structures. Both the upper and lower plates include two layers of PCBA rigid boards on the outer side. Two layers of PCBA flexible boards are arranged between the two outer PCBA rigid boards. The connecting part is two layers of PCBA flexible boards. The two layers of PCBA flexible boards in the connecting part, the two layers of PCBA flexible boards in the upper plate, and the two layers of PCBA flexible boards in the lower plate are the same two layers of PCBA flexible boards.
3. The eddy current sensor for low-altitude aircraft according to claim 2, characterized in that, The bracket has two circumferentially spaced side positioning frames on its upper side, and a middle positioning frame is provided on the bracket between the two side positioning frames. The circumferential distance between the middle positioning frame and the two side positioning frames is equal. A support pad is provided on the bracket between each middle positioning frame and a side positioning frame.
4. The eddy current sensor for low-altitude aircraft according to claim 3, characterized in that, The side positioning frame includes an inner support column and two outer reinforcing columns, which are arranged radially correspondingly. Both the inner support column and the outer reinforcing columns are hollow columns, with the height of the outer reinforcing columns being higher than that of the inner support column. An outer reinforcing plate is provided between the two outer reinforcing columns. A side support plate is provided between the inner support column and each outer reinforcing column, with the side support plate being at the same height as the inner support column. Each side support plate is provided with a limiting plate integrally connected to the corresponding outer reinforcing column. The length of the limiting plate is less than the length of the side support plate, and an assembly groove is provided on the limiting plate. The assembly groove is connected to the side support column. A gap is left between the support plates. The outer reinforcing plate, two outer reinforcing columns, and two limiting plates form an open isosceles trapezoidal limiting groove. A through connection hole is opened on the bracket below each outer reinforcing column. The middle positioning frame includes two radially corresponding middle support columns. A left support plate and a right support plate are respectively provided on the left and right sides of the two middle support columns. The left and right support plates are both open trapezoidal in shape. Several PCBA board connection holes are opened on the left and right support plates. A through connection hole is opened on the bracket below each middle support column.
5. The eddy current sensor for low-altitude aircraft according to claim 4, characterized in that, The upper plate is supported on a left support plate, a right support plate, a side support plate, an inner support column, and a support pad of equal height. The radial width of the upper plate corresponds to the radial width of the bracket. Two clearance grooves are provided on the upper plate corresponding to the two middle support columns. Several PCBA board connection holes are provided on the upper plate corresponding to the PCBA board connection holes on the left and right support plates. Several fastening bolts with glue pass downward through the corresponding PCBA board connection holes on the upper plate and are inserted into the corresponding PCBA board connection holes on the left or right support plates. The upper plate is fixed to the middle positioning frame. A mating groove is provided on both the left and right sides of the upper plate corresponding to each limiting plate. The left and right edges of the upper plate extend into the corresponding limiting grooves. A wire harness is connected to the upper plate.
6. The eddy current sensor for low-altitude aircraft according to claim 5, characterized in that, The bracket has an annular mounting groove on its lower side, which is coaxial with the bracket. The depth of the mounting groove is less than the thickness of the bracket. The inner circumference of the annular lower plate has several circumferentially distributed protruding positioning parts. The lower plate and each protruding positioning part are matched and embedded in the mounting groove. Each protruding positioning part is fixed to the bracket by heat riveting. The outer circumferential edge of the annular bracket has a bypass groove corresponding to the connecting part. The connecting part passes through the bypass groove upward. The thickness of the lower plate is less than the depth of the mounting groove. The mounting groove is also filled with epoxy glue to seal the lower plate.
7. A low-altitude aircraft eddy current sensor according to any one of claims 4-6, characterized in that, The bracket is also provided with several sets of through-connecting holes II distributed at intervals along the arc direction. Each set of through-connecting holes II includes two through-connecting holes II distributed at intervals along the radial direction. Each through-connecting hole II is staggered from the upper plate. Multiple fasteners pass through each through-connecting hole I and through-connecting hole II to fix the bracket to the motor housing. The bracket is provided with two positioning pin holes spaced 180° apart along the circumference. The two positioning pin holes are a round hole and an oblong hole, respectively.
8. A low-altitude aircraft eddy current sensor according to any one of claims 1-6, characterized in that, The eddy current induction coil is arranged on the lower plate, and the chip and other components are arranged on the upper plate. The area where the chip and other components are arranged is offset from the area of the lower plate projected vertically upward on the upper plate.
9. A method for manufacturing a low-altitude aircraft eddy current sensor according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Insert the lower plate of the PCBA board into the mounting groove on the lower side of the bracket, and fix the lower plate and the bracket by heat riveting; (2) Pour epoxy glue into the mounting groove of the bracket to cure and fix the lower plate; (3) Fold the upper plate of the PCBA board onto the upper side of the bracket. The connecting part of the PCBA board passes through the bypass groove, so that the left and right edges of the upper plate are respectively fitted into the limiting grooves of the two side positioning frames. The upper plate is supported on the left support plate, right support plate, side support plate, inner support column and support pad of equal height. (4) Insert several fastening bolts with glue downward through the corresponding PCBA board connection holes on the upper plate and into the corresponding PCBA board connection holes on the left or right support plate to fix the upper plate to the bracket.