A hollow inductive encoder

Abstract

The present invention discloses a hollow inductive encoder, which relates to the field of encoders. The hollow inductive encoder comprises a stator assembly and a rotor assembly arranged in parallel and facing each other. The stator assembly includes a stator protective housing, a signal plate, and a coil plate. A first excitation coil, a second excitation coil, and a third excitation coil are concentrically arranged on the coil plate. The rotor assembly includes a rotor protective housing and a code disk. N sector-shaped first copper foils are evenly arranged in the circumferential direction on the radially inner side of the code disk, and the first copper foils face the first induction coils. M sector-shaped second copper foils are evenly arranged in the circumferential direction on the radially outer side of the code disk, and the second copper foils face the second induction coils, where M>N. Compared with the prior art, the hollow inductive encoder provided by the present invention can adapt to various operating conditions, output precise angle values ​​with high stability, improve measurement accuracy, enhance the system's dynamic performance and stability, and enhance anti-interference capabilities.

Description

Technical Field

[0001] The present invention relates to the field of encoders, and in particular to a hollow inductive encoder. Background Art

[0002] Inductive encoders operate based on the principle of electromagnetic induction. An excitation coil generates a high-frequency magnetic field, causing the initial differential output of the induction coil to be zero. When a ferrite or conductor enters the field, eddy currents create a reverse magnetic field that interferes with the original magnetic field, causing the output voltage of the induction coil to change. This change is correlated with the object's position, and through signal processing, angle, position, and other measurement results can be converted. Inductive encoders are widely used in a wide range of fields, including industrial automation, automotive and transportation, aerospace, energy, and environmental protection equipment. These fields often face harsh operating conditions such as high dust and oil content, humid and underwater environments, strong magnetic interference, and extreme temperatures. Existing hollow inductive encoders typically consist of a stator and rotor made of PCB boards. Under these harsh conditions, they may experience erroneous outputs or even damage and malfunction. To ensure that the encoder can withstand harsh operating conditions, a hollow inductive encoder with high environmental adaptability and highly stable output is needed. Summary of the Invention

[0003] In view of the above problems, the present invention provides a hollow inductive encoder to solve the problem that the hollow inductive angle encoder in the prior art cannot adapt to various working conditions and is easily damaged.

[0004] The present invention provides a hollow inductive encoder, comprising a stator assembly and a rotor assembly arranged in parallel and facing each other, the stator assembly comprising a stator protective shell having an open first annular accommodating cavity; a signal board arranged in the first annular accommodating cavity; a coil board electrically connected to the signal board, arranged at the opening of the first annular accommodating cavity and closing the opening, a first excitation coil, a second excitation coil and a third excitation coil concentrically arranged on the coil board and connected in series through PCB leads and layer-changing holes, a first induction coil being arranged in the induction space between the first excitation coil and the second excitation coil, a second induction coil being arranged in the induction space between the second excitation coil and the third excitation coil, the first induction coil and the second induction coil being respectively connected through PCB leads and layer-changing holes The leads and the layer-changing holes lead out the induction signals; the rotor assembly includes a rotor protective shell having an open second annular accommodating cavity; a code disk is arranged at the opening of the second annular accommodating cavity and closes the opening; N first copper foils are evenly arranged in the circumferential direction on the radial inner side of the code disk, and the first copper foils are directly opposite to the first induction coil; M second copper foils are evenly arranged in the circumferential direction on the radial outer side of the code disk, and the second copper foils are directly opposite to the second induction coil, where M>N.

[0005] Preferably, it further comprises an isolation plate, which is arranged between the signal plate and the coil plate and is welded to the signal plate and the coil plate respectively.

[0006] Preferably, the isolation board is a FR4 blank board.

[0007] Preferably, a plurality of first potting holes are formed at the bottom of the first accommodating cavity; a plurality of second potting holes are formed at the bottom of the second accommodating cavity.

[0008] Preferably, a signal line is further included. A line outlet slot is provided on the stator protective shell. The line outlet slot is located on the outer periphery of the stator protective shell. The signal line passes through the line outlet slot and is connected to the signal board.

[0009] Preferably, a stator mounting surface is provided on the outer circumference of the stator protective shell, and a plurality of groups of stator mounting holes are provided on the stator mounting surface; a rotor mounting surface is provided on the inner circumference of the rotor protective shell, and a plurality of groups of rotor mounting holes are provided on the rotor mounting surface.

[0010] Preferably, the first induction coil and the second induction coil are both sinusoidally periodic.

[0011] Preferably, the N first copper foils and the M second copper foils are all copper foil rows in which metal copper foil and insulating medium are evenly spaced apart.

[0012] Preferably, in the axial orthographic projection of the rotor assembly on the stator assembly, the second copper foil covers the second induction coil and the upper and lower edge arcs of the second copper foil overlap with the third excitation coil and the second excitation coil respectively, and the first copper foil covers the first induction coil and there is a gap between the edge of the first copper foil and the second excitation coil.

[0013] Preferably, a 180° symmetrical position compensation is set with the center of the coil plate as the center of the circle where the excitation coil is connected in series through the PCB lead and the layer-changing hole; and a 180° symmetrical position compensation is set with the center of the coil substrate as the center of the circle where the induction coil leads out the induction signal through the PCB lead and the layer-changing hole respectively.

[0014] Preferably, the compensation setting is a compensation via or a compensation pad.

[0015] Compared with the existing technology, the hollow inductive encoder provided by the present invention can adapt to various working conditions, output accurate angle values ​​with high stability, improve measurement accuracy, enhance system dynamic performance and stability, and improve anti-interference ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a hollow inductive encoder.

[0017] Figure 2 It is a schematic diagram of the explosion of a hollow inductive encoder.

[0018] Figure 3 It is a cross-sectional diagram of a hollow inductive encoder.

[0019] Figure 4 This is a schematic diagram of the stator protective shell of a hollow inductive encoder.

[0020] Figure 5 It is a schematic diagram of a hollow inductive encoder rotor protective shell.

[0021] Figure 6 This is a schematic diagram of a hollow inductive encoder stator assembly.

[0022] Figure 7 It is a schematic diagram of a hollow inductive encoder rotor assembly.

[0023] Description of reference numerals:

[0024] 1. Stator assembly, 11. Stator protective shell, 111. First annular accommodating cavity, 112. First potting hole, 113. Wire outlet slot, 114. Stator mounting surface, 1141. Stator mounting hole, 12. Coil plate, 121. First excitation coil, 122. Second excitation coil, 123. Third excitation coil, 124. First induction coil, 125. Second induction coil, 126. Compensation via, 13. Signal board, 14. Isolation board;

[0025] 2. Rotor assembly, 21. Rotor protective housing, 211. Second annular accommodating cavity, 212. Second potting hole, 213. Rotor mounting surface, 2131. Rotor mounting hole, 22. Code disk, 221. First copper foil, 222. Second copper foil;

[0026] 3. Signal line. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings.

[0028] The embodiment of the present invention discloses a hollow inductive encoder, referring to Figures 1 to 7 A hollow inductive encoder comprises a stator assembly 1 and a rotor assembly 2 arranged in parallel and facing each other, and a signal line 3 led out from the stator assembly 1, and the rotor assembly 1 is projected on the stator assembly 2 in the axial direction.

[0029] The stator assembly 1 includes a stator shielding case 11 , a coil plate 12 , a signal plate 13 and an isolation plate 14 .

[0030] The stator protective shell 11 is made of metal aluminum. A stator mounting surface 114 is designed on the outer peripheral side of the stator protective shell 11. Three groups of stator mounting holes 1141 symmetrically distributed and located on the same circumference are set on the stator mounting surface 114. The inner holes of any group of symmetrical stator mounting holes 1141 located on the same diameter are threaded and used as disassembly holes, and a wire outlet slot 113 is opened between any two stator mounting holes 1141.

[0031] Inside the stator mounting surface 114 is a first annular cavity 111, open at one end. A signal board 13 is positioned within this first cavity 111. Signal wire 3 is introduced into this cavity through the wire outlet slot 113 and connected to the signal board 13. Coil board 12 is positioned at the opening of this cavity 111 and seals it. Because coil board 12 lacks a shielding layer, an isolation plate 14 made of a blank FR4 board is positioned between the two. This serves to increase the distance between the two, reduce their impact, and enhance signal quality. Isolation plate 14 is the same size and shape as signal board 13 and is welded to both via pads and half-holes, respectively, to achieve electrical connection between coil board 12 and signal board 13.

[0032] Four symmetrically distributed first potting holes 112 are provided at the bottom of the first annular housing cavity 111, facing the opening. The four first potting holes 112, located on the same circumference, are grouped together. Any one of the first potting holes 112 can be selected for the entry of liquid epoxy glue. The first potting holes 112 within the same group balance air pressure to ensure that the liquid epoxy glue fully fills the first annular housing cavity 111. The two first potting holes 112 in another group can be used for leveling the stator assembly.

[0033] The coil board 12 adopts a 4-layer circular PCB multilayer board. On the third and fourth layers, a first excitation coil 121, a second excitation coil 122 and a third excitation coil 123 of different diameters are concentrically arranged, which are connected in series through PCB leads and layer-changing holes. Each group of excitation coils is wound in an overlapping manner on each layer, and each layer is wound with three turns of annular coils. The winding directions of two adjacent groups of excitation coils are opposite, and an annular induction space is formed between the two groups of excitation coils; a first induction coil 124 is arranged in the induction space between the first excitation coil 121 and the second excitation coil 122, and a second induction coil 125 is arranged in the induction space between the second excitation coil 122 and the third excitation coil 123. The first induction coil 124 and the second induction coil 125 are both composed of four sinusoidal curves with multiple periods in polar coordinates. The four curves are based on a phase of 0°, with phase differences of 90°, 180°, and 270°. The number of periods of the first induction coil 124 is less than that of the second induction coil 125. Each sinusoidal curve is alternately arranged on the third and fourth layers of the coil plate 12, switching layers every half a period. The first and second induction coils 124 and 125 both extract their induction signals via PCB traces and layer-switch holes. To ensure the symmetry of the coil plate, compensation vias 126 are placed 180° symmetrically around the center of the coil substrate, at the points where the excitation coils are connected in series via the PCB traces and layer-switch holes, and at the points where the induction coils extract their induction signals via the PCB traces and layer-switch holes, respectively. The size and shape of the compensation vias 126 are identical to those of the layer-switch holes.

[0034] The rotor assembly 2 includes a rotor protective shell 21 and a code wheel 22 .

[0035] The rotor shield 21 is made of aluminum. A rotor mounting surface 213 is designed on its inner circumference. This surface is provided with three sets of symmetrically distributed rotor mounting holes 2131 located on the same circumference. The inner holes of any set of these symmetrical, co-diameter rotor mounting holes 2131 are threaded for removal. Outside the rotor mounting surface 213 is a second, open-ended annular cavity 211. The code wheel 22 is positioned at the opening of this second annular cavity 211 and seals it.

[0036] Four second potting holes 212 are symmetrically distributed and located on the same circumference at the bottom of the second annular accommodating cavity 211 opposite the opening. The distribution and function of the second potting holes 212 are similar to those of the first potting holes 112.

[0037] On the radial inner side of the code disk 22, 45 fan-shaped copper foils are evenly arranged in the circumferential direction as the first copper foil 221. The first copper foil 221 is opposite to the first induction coil 124 on the coil plate 12. The orthographic projection of the first copper foil 221 on the coil plate 12 covers the first induction coil 124 but does not overlap with the second excitation coil 122 and the third excitation coil 123. Instead, a gap of 0.1 mm is maintained to generate an eddy current effect.

[0038] On the radial outside of the code disk 22, 125 fan-shaped copper foils are evenly arranged in the circumferential direction as the second copper foil 222. The second copper foil 222 is opposite to the second induction coil 125. The orthographic projection of the second copper foil 222 on the coil plate 12 covers the second induction coil 125, and the edge arcs of the fan-shaped copper foil overlap with the first excitation coil 121 and the second excitation coil 112 respectively to generate an eddy current effect.

[0039] The first copper foil 221 and the second copper foil 222 are both copper foil rows in which metal copper foil and insulating medium are evenly spaced apart.

[0040] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A hollow inductive encoder, comprising a stator assembly and a rotor assembly arranged in parallel and facing each other, characterized in that: The stator assembly comprises: A stator protective shell having an open first annular accommodating cavity, wherein a stator mounting surface is provided on the outer circumference of the stator protective shell, and a plurality of groups of stator mounting holes are provided on the stator mounting surface; a signal plate, disposed in the first annular accommodating cavity; a coil plate, electrically connected to the signal plate, disposed at the opening of the first annular accommodating cavity and closing the opening; a first excitation coil, a second excitation coil, and a third excitation coil concentrically disposed on the coil plate, connected in series via PCB leads and layer-changing holes; a first induction coil disposed within the induction space between the first excitation coil and the second excitation coil; a second induction coil disposed within the induction space between the second excitation coil and the third excitation coil; and the first induction coil and the second induction coil respectively lead out induction signals via the PCB leads and the layer-changing holes; The rotor assembly comprises: A rotor protective shell having an open second annular accommodating cavity, wherein an inner circumference of the rotor protective shell is provided with a rotor mounting surface, and the rotor mounting surface is provided with a plurality of groups of rotor mounting holes; A code disk is disposed at the opening of the second annular accommodating cavity and closes the opening, wherein N first copper foils are evenly arranged in the circumferential direction on the radially inner side of the code disk, and the first copper foils are directly opposite to the first induction coil; and M second copper foils are evenly arranged in the circumferential direction on the radially outer side of the code disk, and the second copper foils are directly opposite to the second induction coil, where M>N; Among them, a 180° symmetrical position compensation is set with the center of the coil plate as the center of the circle where the excitation coil is connected in series through the PCB lead and the layer-changing hole; a 180° symmetrical position compensation is set with the center of the coil substrate as the center of the circle where the induction coil leads out the induction signal through the PCB lead and the layer-changing hole respectively.

2. A hollow inductive encoder according to claim 1, characterized in that: It also includes a shielding plate isolation plate, which is arranged between the signal plate and the coil plate and is welded to the signal plate and the coil plate respectively.

3. The hollow inductive encoder according to claim 2, characterized in that: The isolation board is a FR4 blank board.

4. The hollow inductive encoder according to claim 1, characterized in that: It also includes a signal line. The stator protective shell is provided with a line outlet slot, the line outlet slot is located on the outer periphery of the stator protective shell, and the signal line passes through the line outlet slot and is connected to the signal board.

5. The hollow inductive encoder according to claim 1, characterized in that: The first induction coil and the second induction coil are both sinusoidally periodic.

6. The hollow inductive encoder according to claim 1, characterized in that: The N first copper foils and the M second copper foils are all copper foil rows in which metal copper foil and insulating medium are evenly spaced apart.

7. The hollow inductive encoder according to claim 1, characterized in that: In the axial orthographic projection of the rotor assembly on the stator assembly, the second copper foil covers the second induction coil and the upper and lower edge arcs of the second copper foil overlap with the third excitation coil and the second excitation coil respectively; the first copper foil covers the first induction coil and there is a gap between the edge of the first copper foil and the second excitation coil.

8. The hollow inductive encoder according to claim 1, characterized in that: The compensation setting is a compensation via or a compensation pad.

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