Hollow inductive encoder

Abstract

Disclosed in the present invention is a hollow inductive encoder, relating 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 comprises a stator protective housing, a signal board, and a coil board. A first excitation coil, a second excitation coil, and a third excitation coil are concentrically arranged on the coil board. The rotor assembly comprises a rotor protective housing and a code disk. N sector-shaped first copper foils are uniformly arranged in the circumferential direction on the radially inner side of the code disk, with the first copper foils facing the first inductive coil. M sector-shaped second copper foils are uniformly arranged in the circumferential direction on the radially outer side of the code disk, with the second copper foils facing the second inductive coil, wherein M>N. Compared with the prior art, the hollow inductive encoder provided by the present invention is capable of adapting to various working conditions to output precise angle values with high stability, thereby improving measurement precision, enhancing the dynamic performance and stability of the system, and improving anti-interference capability.

Description

A hollow inductor encoder Technical Field

[0001] This invention relates to the field of encoders, and more particularly to a hollow inductive encoder. Background Technology

[0002] Inductive encoders operate based on the principle of electromagnetic induction. The excitation coil generates a high-frequency magnetic field, causing the initial differential output of the induction coil to be zero. When ferrite or a conductor enters, due to the eddy current effect, it generates a reverse magnetic field that interferes with the original magnetic field, causing a change in the output voltage of the induction coil. This change is related to the position of the object, and after signal processing, measurement results such as angle and position can be calculated. Inductive encoders are widely used in many fields such as industrial automation, automotive and transportation, aerospace, energy and environmental protection equipment, etc. These fields often face harsh conditions such as high dust / oil pollution, humid / underwater environments, strong magnetic interference, and extreme temperatures. Existing hollow inductive encoders are generally composed of stators and rotors made of PCB boards, which may face erroneous outputs or even damage and inoperability under harsh conditions. In order to ensure that the encoder can adapt to harsh conditions, a hollow inductive encoder with high environmental adaptability and high stable output is needed. Technical solutions

[0003] To address the aforementioned problems, this invention provides a hollow inductive encoder to solve the issues that existing hollow inductive angle encoders cannot adapt to various working conditions and are easily damaged.

[0004] This invention provides a hollow inductive encoder, comprising a stator assembly and a rotor assembly arranged in parallel and facing each other. The stator assembly includes a stator protective shell and a first annular receiving cavity with an opening; a signal board disposed within the first annular receiving cavity; and a coil board electrically connected to the signal board, disposed at the opening of the first annular receiving cavity and closing the opening. A first excitation coil, a second excitation coil, and a third excitation coil are concentrically arranged on the coil board and connected in series via PCB leads and layer-change holes. A first induction coil is disposed within the sensing space between the first excitation coil and the second excitation coil, and a second induction coil is disposed within the sensing space between the second excitation coil and the third excitation coil. The first and second induction coils are respectively connected via PCB leads. The lead wire and the layer replacement hole lead out the induction signal; the rotor assembly includes a rotor protective shell and a second annular receiving cavity with an opening; a code disk is disposed at the opening of the second annular receiving cavity and closes the opening, N first copper foils are evenly arranged in the circumferential direction on the radially inner side of the code disk, the first copper foils are directly opposite 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, the second copper foils are directly opposite the second induction coil, where M>N.

[0005] Preferably, it further includes an isolation plate disposed between the signal plate and the coil plate, and welded to the signal plate and the coil plate respectively.

[0006] Preferably, the isolation plate is an FR4 blank plate.

[0007] Preferably, the bottom of the first receiving cavity is provided with a plurality of first filling holes; the bottom of the second receiving cavity is provided with a plurality of second filling holes.

[0008] Preferably, it also includes a signal line, and the stator protective housing has a cable outlet groove located on the outer periphery of the stator protective housing. The signal line passes through the cable outlet groove and connects to the signal board.

[0009] Preferably, the stator protective shell has a stator mounting surface on its outer periphery, and the stator mounting surface has a plurality of sets of stator mounting holes; the rotor protective shell has a rotor mounting surface on its inner periphery, and the rotor mounting surface has a plurality of sets of rotor mounting holes.

[0010] Preferably, both the first induction coil and the second induction coil exhibit sinusoidal periodicity.

[0011] Preferably, the N first copper foils and the M second copper foils are both rows of copper foils arranged with metal copper foil and insulating medium evenly spaced.

[0012] Preferably, in the axial orthogonal projection of the rotor assembly onto 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 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, the excitation coil is compensated at a 180° symmetrical position with the center of the coil board as the center at the point where the excitation coil is connected in series through the PCB leads and the layer replacement hole; the induction coil is compensated at a 180° symmetrical position with the center of the coil substrate as the center at the point where the induction coil leads out the induction signal through the PCB leads and the layer replacement hole respectively.

[0014] Preferably, the compensation is set to compensate for vias or compensate for pads. Beneficial effects

[0015] Compared with existing technologies, the hollow inductive encoder provided by this invention can adapt to various working conditions and output accurate angle values ​​with high stability, thereby improving measurement accuracy, enhancing system dynamic performance and stability, and improving anti-interference ability. Attached Figure Description

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

[0017] Figure 2 is an exploded view of a hollow inductive encoder.

[0018] Figure 3 is a schematic cross-sectional view of a hollow inductive encoder.

[0019] Figure 4 is a schematic diagram of a stator protective housing for a hollow inductive encoder.

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

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

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

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Stator assembly; 11. Stator protective shell; 111. First annular cavity; 112. First potting hole; 113. 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 plate;

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

[0026] 3. Signal line. Embodiments of the present invention

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

[0028] An embodiment of the present invention discloses a hollow inductive encoder. Referring to Figures 1 to 7, the hollow inductive encoder includes 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. Furthermore, the rotor assembly 1 is positioned within the axial orthogonal projection of the rotor assembly 1 onto the stator assembly 2.

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

[0030] The stator protective shell 11 is made of aluminum. A stator mounting surface 114 is designed on the outer periphery of the stator protective shell 11. Three sets of symmetrically distributed stator mounting holes 1141 located on the same circumference are provided on the stator mounting surface 114. The inner hole of any set of symmetrical stator mounting holes 1141 located on the same diameter is provided with threads for disassembly. A cable outlet groove 113 is opened between any two stator mounting holes 1141.

[0031] Inside the stator mounting surface 114 is a first annular receiving cavity 111 with one end open. A signal board 13 is disposed within the first receiving cavity 111. Signal lines 3 are introduced into the first receiving cavity 111 and connected to the signal board 13 via a cable outlet groove 113. A coil board 12 is disposed at the opening of the first receiving cavity 111 and closes the opening. Since the coil board 12 does not have a shielding layer, a blank FR4 board isolation plate 14 is placed between the signal board 13 and the coil board 12 to increase the distance between them, reduce the influence of the signal board 13 on the coil board 12, and enhance the signal. The isolation plate 14 is the same size and shape as the signal board 13 and is soldered to both the signal board 13 and the coil board 12 via pads and half-holes, respectively, to achieve electrical connection between the coil board 12 and the signal board 13.

[0032] Four symmetrically distributed first potting holes 112 located on the same circumference are provided at the bottom of the first annular receiving cavity 111, directly opposite the opening. The four first potting holes 112 are grouped together, with any one of them used for the entry of liquid epoxy adhesive. The first potting holes 112 in the same group can balance the air pressure to ensure that the liquid epoxy adhesive can fill the first annular receiving cavity 111. The other group of two first potting holes 112 can be used for leveling the stator assembly.

[0033] The coil board 12 is a four-layer circular PCB multilayer board. On the third and fourth layers, there are three excitation coils of different diameters, namely a first excitation coil 121, a second excitation coil 122, and a third excitation coil 123, which are connected in series through PCB leads and layer replacement holes. Each group of excitation coils is wound in an overlapping manner on each layer, and each layer has three turns of circular coil. The winding directions of adjacent groups of excitation coils are opposite, and a circular induction space is formed between the two groups of excitation coils. A first induction coil 124 is set in the induction space between the first excitation coil 121 and the second excitation coil 122, and a second induction coil 125 is set 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 cycles in polar coordinates. The four curves are based on a 0° phase and have phase differences of 90°, 180°, and 270°. The number of cycles of the first induction coil 124 is less than the number of cycles of the second induction coil 125. Each sine curve is alternately arranged on the third and fourth layers of the coil board 12, changing layers every half cycle. The first induction coil 124 and the second induction coil 125 both lead out induction signals through PCB leads and layer-change holes. To ensure the symmetry of the coil board, compensation vias 126 are placed at 180° symmetrical positions centered on the coil substrate, where the excitation coils are connected in series through PCB leads and layer-change holes, and where the induction coils lead out induction signals through PCB leads and layer-change holes respectively. The size and shape of the compensation vias 126 are completely consistent with the size and shape of the layer-change holes.

[0034] The rotor assembly 2 includes a rotor protective shell 21 and an encoder 22.

[0035] The rotor protective shell 21 is made of aluminum. A rotor mounting surface 213 is designed on the inner circumference of the rotor protective shell 21. Three sets of symmetrically distributed rotor mounting holes 2131 located on the same circumference are provided on the rotor mounting surface 213. The inner hole of any one set of symmetrical rotor mounting holes 2131 located on the same diameter is threaded for use as a disassembly hole. On the outer side of the rotor mounting surface 213 is a second annular receiving cavity 211 with one end open. An encoder 22 is located at the opening of the second annular receiving cavity 211 and closes the opening.

[0036] Four symmetrically distributed second filling holes 212 are provided at the bottom of the second annular cavity 211, directly opposite the opening, and located on the same circumference. The distribution and function of the second filling holes 212 are the same as those of the first filling 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 directly 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, it maintains a gap of 0.1 mm to generate eddy current effect.

[0038] On the radial outer side 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 directly opposite the second induction coil 125. The orthogonal projection of the second copper foil 222 on the coil plate 12 covers the second induction coil 125, and the arc edge of the fan-shaped copper foil overlaps the first excitation coil 121 and the second excitation coil 112 respectively to generate eddy current effect.

[0039] The first copper foil 221 and the second copper foil 222 are both rows of copper foils with metal copper foil and insulating medium evenly spaced.

[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 embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing 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 includes: The stator protective shell has an open first annular receiving cavity, and a stator mounting surface is provided on the outer periphery of the stator protective shell. The stator mounting surface is provided with a plurality of sets of stator mounting holes. The signal board is disposed within the first annular cavity; A coil board, electrically connected to the signal board, is disposed at the opening of the first annular cavity and closes the opening. A first excitation coil, a second excitation coil, and a third excitation coil are concentrically disposed on the coil board and connected in series through PCB leads and layer-change holes. A first induction coil is disposed in the induction space between the first excitation coil and the second excitation coil, and a second induction coil is disposed in the induction space between the second excitation coil and the third excitation coil. The first induction coil and the second induction coil respectively lead out the induction signal through PCB leads and layer-change holes. The rotor assembly includes: The rotor protective shell has an open second annular receiving cavity, and a rotor mounting surface is provided on the inner circumference of the rotor protective shell. The rotor mounting surface is provided with a plurality of sets of rotor mounting holes. A code disk is disposed at the opening of the second annular cavity and closes the opening. 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 the first induction coil. 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 the second induction coil, where M>N. The compensation is provided at a 180° symmetrical position with the center of the coil board as the center at the point where the excitation coil is connected in series through the PCB leads and the layer replacement hole; the compensation is also provided at a 180° symmetrical position with the center of the coil substrate as the center at the point where the induction coil leads out the induction signal through the PCB leads and the layer replacement hole respectively.

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

3. A hollow inductive encoder according to claim 2, characterized in that, The isolation plate is an FR4 blank plate.

4. A hollow inductive encoder according to claim 1, characterized in that, It also includes signal lines. The stator protective housing has a cable outlet groove located on the outer periphery of the stator protective housing. The signal lines pass through the cable outlet groove and connect to the signal board.

5. A hollow inductive encoder according to claim 1, characterized in that, Both the first induction coil and the second induction coil exhibit sinusoidal periodicity.

6. A hollow inductive encoder according to claim 1, characterized in that, Both N first copper foils and M second copper foils are rows of copper foils arranged with metal copper foil and insulating medium evenly spaced.

7. A hollow inductive encoder according to claim 1, characterized in that, In the axial orthogonal projection of the rotor assembly onto 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 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. A hollow inductive encoder according to claim 1, characterized in that, The compensation is set to compensate vias or compensate pads.

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