Sensing grid type displacement sensor

Abstract

The utility model discloses a sensing grating type displacement sensor which comprises a grating ruler assembly and an inductive head, and after the grating ruler assembly and the inductive head are installed on a device to be measured, the inductive head can move relative to the length direction of the grating ruler assembly. The grating ruler assembly is provided with a grating belt, grids are arranged in the length direction of the grating belt in an array mode, the grids are through holes or are of groove-shaped structures which are sunken downwards, at least two induction coils are arranged in the induction head, and when current is supplied to the induction coils, mutual induction electromotive force can be generated between the induction coils; when the induction head moves along the length direction of the grid ruler assembly, the mutual induction electromotive force between the induction coils changes along with the arrangement rule of the grids. The beneficial effects of the utility model are that displacement measurement is carried out through the change rule between the mutual inductance of the grating ruler and the coil, a novel displacement sensing measurement mode is provided, and the measurement accuracy is extremely excellent.

Description

TECHNICAL FIELD

[0001] The utility model relates to displacement sensor technical field, concretely relates to a displacement sensor of feel grating type. BACKGROUND

[0002] The displacement sensor is a kind of component for measuring and recording the moving distance of moving part, and its working principle is mainly based on the conversion of mechanical displacement into electrical signal or other forms of information output, to meet the transmission, processing, storage, display, record and control requirements of information.

[0003] Based on the different measurement principles, the current displacement sensor mainly has resistance displacement sensor, inductance displacement sensor, capacitive displacement sensor, photoelectric displacement sensor, ultrasonic displacement sensor and the like. With the continuous development of industrial automation, different fields also put forward more stringent requirements to the accuracy and precision of displacement sensor measurement. And based on the sensor of current existing measurement principle, it is almost close to development limit, and it is difficult to achieve more obvious technical breakthrough.

[0004] Therefore, applicant explores a new type of displacement sensor based on the principle of mutual inductance electromotive force change of multiple coils. CONTENT OF UTILITY MODEL

[0005] Therefore, the utility model provides a displacement sensor of feel grating type, and displacement measurement is carried out by the change rule between grating ruler and mutual inductance electromotive force, to provide a displacement sensor with higher measurement accuracy.

[0006] To achieve the above-mentioned purpose, the technical scheme of the utility model is as follows:

[0007] A displacement sensor of feel grating type, and the key lies in, including grating ruler assembly and inductive head, grating ruler assembly and inductive head are installed to the equipment to be measured, inductive head can move relative to the length direction of grating ruler assembly;Grating ruler assembly has grating belt, grating belt length direction array is provided with grating, grating is through-hole or is downward recessed groove structure, inductive head is built-in at least two induction coils, when current is passed to the induction coil, mutual inductance electromotive force can be generated between each induction coil;The mutual inductance electromotive force between each induction coil changes with the arrangement rule of grating during the movement of inductive head along the length direction of grating ruler assembly.

[0008] Preferably, grating ruler assembly is composed of second insulating base layer, second flexible glue layer, grating belt, first flexible glue layer and first insulating base layer in turn from top to bottom.

[0009] In the traditional grid scale process, the grid is usually formed by directly printing copper foil on the PCB. Although the PCB has the advantages of mature manufacturing and low cost, the existing PCB photosensitive film manufacturing process has a large absolute tolerance, generally plus or minus 0.2 mm, which is difficult to achieve high-precision manufacturing. The base material of the PCB is usually FR4, which has a large thermal deformation coefficient, which causes thermal deformation of the copper foil layer. The rigidity of the PCB is insufficient, for example, more than 0.5 meters will cause warping, the impact resistance of the PCB itself is insufficient, for example, metal collision can easily damage the PCB, the corrosion resistance of the PCB is insufficient, and it cannot be directly applied to humid, water, various oil products, chemical media and other environments. These all affect the development of the utility model technology in high-precision, large-scale displacement measuring instruments.

[0010] Therefore, the grid scale assembly using the above stacking method, the metal grid belt is clamped between the two insulating layers to form a grid scale, the metal grid belt is manufactured separately, and is not solidified and connected with the insulating layer, so that the metal grid belt has a stable thermal deformation coefficient determined by the material of the body, and when the whole grid scale is bent, the metal grid belt can slide in the insulating layer to maintain its linear size, the manufacturing precision of the metal grid belt is higher, and high-precision stamping, CNC or laser engraving technology is adopted to easily achieve plus or minus 0.01 mm. The metal grid belt can be manufactured as a continuous strip to realize continuous precision of a long-size grid scale, and is convenient for production and assembly.

[0011] Preferably, the grid scale assembly is wrapped with a heat shrink tube.

[0012] Preferably, the grid scale assembly is provided with a wrapping component, the wrapping component is open at the top and has a support section above the grid belt formed at positions corresponding to the two ends of the opening, and a glue-like filler is arranged between the support section and the grid belt.

[0013] Preferably, the bottom of the first insulating base layer is connected with a base plate by a threaded fastener or a riveting method, and the threaded fastener is arranged between two adjacent grid belts of the grid belt. When the threaded fastener is used for connection, the threaded fastener can be fastened from the base plate (9) to the first insulating layer (2), or fastened from the first insulating layer to the base plate.

[0014] Preferably, the inductive head comprises an outer shell and a coil PCB plate fixedly arranged in the outer shell, and the inductive coil is arranged on the coil PCB plate.

[0015] Preferably, among the inductive coils, one inductive coil (a rectangular frame-shaped primary coil) and the remaining inductive coils (secondary coils) are arranged in the primary coil with a phase difference of 90°.

[0016] Preferably, the number of secondary coils is 2 or 3 or 4.

[0017] Preferably, the grid belt is a metal grid belt, and a metal segment is formed between two adjacent grids, and the length ratio between the metal segment and the grid is 3:1.

[0018] Preferably, the total length of the metal segment and the adjacent grid is 10.24 mm or 5.12 mm.

[0019] Preferably, at least two grid ruler assemblies are arranged in parallel in space, and the number of the sensing heads corresponds to the number of the grid ruler assemblies; the length of the metal segment and the grid is a grid pitch period, and the grid pitch periods of the grid ruler assemblies are different.

[0020] Preferably, the difference between the grid pitch periods of the grid ruler assemblies is an integer multiple of the grid pitch period.

[0021] Preferably, after the grid ruler assembly and the sensing head are installed on the equipment to be measured, the distance between the sensing head and the grid belt is 0-2 mm.

[0022] Preferably, the grid ruler assembly is designed in a strip-shaped structure, an arc-shaped structure or a circular structure, so as to be suitable for curved surface and rotation detection.

[0023] Preferably, the grid belt is a magnetic grid belt.

[0024] Compared with the prior art, the utility model has the beneficial effects that:

[0025] 1. The sensing grid type displacement sensor provided by the utility model measures displacement through the change rule between the grid ruler and the coil mutual inductance motor, provides a novel displacement sensing measurement mode, and has extremely excellent measurement accuracy. The resolution of the inductive grid ruler can reach 20 nm at most, which is a very important factor for some high-quality motion control applications, such as a micro-motion platform. The output noise of the inductive sensor is low, and the output signal quality is good, and the overall signal-to-noise ratio is very excellent.

[0026] 2. The chip integrated with the inductive coil is small in size and thin in thickness, and the thickness can reach 0.9 mm. The overall thickness of the sensing head can be controlled to be less than 2 mm. The installation space of the customer is saved, and the customer can integrate the chip on the PCB circuit board.

[0027] 3. The anti-magnetic field interference performance is excellent. The inductive coil of the sensing grid type displacement sensor can pass high-frequency excitation current. The electromagnetic interference in the external environment is a low-frequency electromagnetic field, and the anti-magnetic field interference can be effectively realized. It is especially suitable for various motors and medical nuclear magnetic resonance fields.

[0028] 4. The inductive head and the grating assembly can be non-contact measurement, which can realize long-time wear-free operation and maintenance-free.

[0029] 5. The inductive medium is various, and steel, aluminum, copper and other metal materials can be used as the inductive medium of the grating.

[0030] 6. The robustness is strong, the temperature resistance range of the inductive grating is very large, and the inductive grating can work normally in a severe vibration environment and can also be applied in a vacuum environment. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a structure schematic view of the grating type displacement sensor.

[0032] Figure 2 It is a schematic view of the arrangement of each inductive coil a in the inductive head B.

[0033] Figure 3 It is a schematic view of the principle that the metal or magnet target block close to the two mutual inductance coils causes the change of mutual inductance electromotive force.

[0034] Figure 4 It is a schematic view of the implementation structure of the grating assembly A.

[0035] Figure 5 It is a schematic view that the grating assembly A is wrapped with a closed heat shrink tube 6.

[0036] Figure 6 It is a schematic view that the heat shrink tube 6 is provided with a C-shaped wrapping component 7.

[0037] Figure 7 It is another installation schematic view of the C-shaped wrapping component 7.

[0038] Figure 8 It is a schematic view that the grating assembly A is provided with a base plate 9 at the bottom.

[0039] Figure 9 It is a top view showing the installation position of the threaded fastener c.

[0040] Figure 10 It is a structure schematic view of the inductive head B.

[0041] Figure 11 It is a schematic view that two adjacent grating assemblies A adopt side-by-side parallel layout.

[0042] Figure 12 It is a schematic view that a shielding plate 17 is arranged between two adjacent inductive heads B. DETAILED DESCRIPTION

[0043] To facilitate understanding of the implementation scheme of this specification, this embodiment first briefly explains the principle that a metal or magnetic conductive target block causes the two sets of induction coils to generate a change in mutual electromotive force.

[0044] Please refer to Figure 3 As shown, a secondary coil e is placed within a primary coil d. When an oscillating current is passed through it, a mutual induced electromotive force (EMF) is generated between the primary and secondary coils. When a metallic or magnetic target f approaches, the electromagnetic fields of the two coils are disturbed, causing a change in the mutual induced electromotive force. This change is primarily related to the gap between the target f and the coils, as well as the projected area of ​​the target f. If at least one of the primary coil d and the secondary coil e is a functional coil. Figure 3 The secondary coil e is a function type. At this time, the target block f is Figure 3 As the target block f moves in the axial direction indicated by the arrow, the coverage area of ​​the secondary coil e changes at different displacement points, causing the mutual electromotive force between the primary coil d and the secondary coil e to change. The fact that the conductive target block f generates reverse resistive magnetic flux, causing the mutual inductance to change, is common knowledge in physics and will not be described in more detail here. Based on this, assuming that the gap between the target block and the coil remains constant and the variation in coverage area is determined by the shape function of the secondary coil e, the variation in the mutual inductance signal is also determined by the variation in coverage area, that is, the variation in displacement. Therefore, a correlated output of the displacement-sensing signal can be obtained.

[0045] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0046] like Figure 1 As shown, a grating type displacement sensor is composed of a scale assembly A and a sensing head B matched with the scale assembly A. After the scale assembly A and the sensing head B are installed in the device to be measured, the sensing head B is arranged on one side of the scale assembly A and can move relative to the length direction of the scale assembly A. The scale assembly A includes at least one scale strip 1, which is made of metal material. The scale strip 1 is arranged with grids 1a in an array along the length direction. The grids 1a are through holes or downwardly concave groove structures. In the scale strip 1, there is a metal segment 1b between two adjacent grids 1a. Combined with the attached Figure 2 It can be seen that the induction head B has at least two induction coils a built in. When an oscillating current is passed through the induction coils a, mutual induction electromotive force can be generated between the induction coils a.

[0047] Based on the above structure, in actual application, the grating assembly A is usually fixedly installed in the equipment to be measured, the sensing head B is usually slidably installed in the equipment to be measured, and the inductive coils a in the sensing head B need to be aligned with one side of the grating belt 1. Since the grid 1a is equivalent to reducing the thickness of the metal material of the grating belt 1 at this position, when the sensing head B passes the position of the grid 1a and the position of the metal segment 1b, the mutual inductive electromotive force between the inductive coils a will certainly be different. Therefore, during the movement of the sensing head B along the length direction of the grating assembly A, the mutual inductive electromotive force between the inductive coils a can change with the arrangement rule of the grid 1a. Based on this, by converting the change rule of the mutual inductive electromotive force into displacement, the displacement of the sensing head B can be obtained, so as to realize the displacement measurement of the target product.

[0048] As shown in Figure 10 In the embodiment, the sensing head B includes an outer shell 10, a coil PCB plate 11 and a circuit PCB plate 12 which are fixedly arranged in the outer shell 10 in layers, the inductive coils a are arranged on the coil PCB plate 11, the coil PCB plate 11 is located at the lower layer, the circuit PCB plate 12 is located at the upper layer, the two are connected through a conductive wire 15, and a filling potting glue 16 is arranged between the two. The circuit PCB plate 12 is connected with a power supply wire 14. In specific application, after the grating assembly A and the sensing head B are installed to the equipment to be measured, the distance between the coil plane in the sensing head B and the surface of the grating belt 1 is preferably 0-2mm, and the distance can be calibrated to 1mm when leaving the factory.

[0049] Please refer to Figure 2 In the embodiment, in each inductive coil a in the sensing head B, one inductive coil a is a rectangular frame-shaped primary coil d, and the others are secondary coils e. Each secondary coil e is a sinusoidal planar coil and is arranged in the primary coil d with a phase difference of 90°. The inductive coils a are printed on the coil PCB plate 11, and each sinusoidal planar coil is arranged in the primary coil d with a phase difference of 90°. Correspondingly, in the grating belt 1, the length ratio between the metal segment 1b and the adjacent grid 1a is 3:1, which is equivalent to 90 degrees of the 360-degree sinusoidal function, that is, 1 / 4. When the sensing head B moves relative to the grating belt 1, the change rule of the inductance of the secondary coil e in a single pitch period is a sinusoidal curve, which is beneficial to data acquisition. As for the number of sinusoidal planar coils, it can be 2 or 3 or 4, etc. The repeated arrangement of multiple sinusoidal coils on the displacement axis is helpful to improve the inductive value. It has been verified that the preferred number is 3 or 4 complete sinusoidal coils.

[0050] In a single grating belt 1, the length sum of one metal segment 1b and one grid 1a is a pitch period, and each period pitch of the grating belt 1 can be set to 10.24mm or 5.12mm, which is beneficial to 12-bit ADC data acquisition.

[0051] The displacement sensor provided by the embodiment can also form an absolute value measurement scheme in application, specifically, at least two grid scale assemblies A are arranged in parallel in space, and the number of the grid scale assemblies A corresponds to the number of the sensing heads B, the grid pitch periods of each grid scale assembly A are different, a plurality of sets of sensing heads B are used to correspond to the respective grid scale assemblies A, and the difference values read by each set of sensing heads B are different at each position, so that the absolute value can be calculated. Further, the difference between the grid pitch periods of each grid scale assembly A can be evenly divided by the value of each grid pitch period. In this way, the absolute value can be easily calculated by a single-chip microcomputer.

[0052] In the application scheme of arranging a plurality of grid scale assemblies A, the planes where the adjacent two grid scale assemblies A are arranged can adopt a side-by-side parallel layout, a directly opposite parallel layout, an angle parallel layout or a vertical parallel layout, and the like. Figure 11 A side-by-side parallel layout scheme is shown. In this scheme, the adjacent two sensing heads B are arranged staggered, so that the interference between the coils can be reduced. In addition, please refer to Figure 12 A shielding plate 17 can also be arranged between the adjacent two sensing heads B to avoid the mutual interference of the coils between the two sensing heads B. The shielding plate 17 is a metal plate.

[0053] In the embodiment, the specific structure of the grid scale assembly A is as follows:

[0054] Please refer to the attached Figure 4 The grid scale assembly A includes a first insulating base layer 2, the grid belt 1 is installed on the upper side of the first insulating base layer 2 through the first flexible adhesive layer 3, the upper side of the grid belt 1 is connected with the second insulating base layer 5 through the second flexible adhesive layer 4, and the second insulating base layer 5 is more rigid than the first insulating base layer 2. In this way, the grid belt 1 can be manufactured separately, and is not solidly connected with the first insulating base layer 2 and the second insulating base layer 5, but is flexibly connected through the flexible adhesive layer. Therefore, the metal grid belt 1 has a stable thermal deformation coefficient determined by the material itself, and can slide in the insulating layer when the entire grid scale is bent, so as to maintain its linear size. In addition, the grid belt 1 is independently processed by using high-precision stamping, CNC or laser engraving technology, and has higher manufacturing precision. At the same time, based on this structure, the grid belt can also be manufactured as a continuous strip, so as to realize the continuous precision of the long-size grid scale and facilitate production and assembly.

[0055] In the above embodiment structure, the second flexible adhesive layer 4 and the second insulating base layer 5 can also be removed, and at this time, the grid scale assembly A is composed of the grid belt 1, the first flexible adhesive layer 3 and the first insulating base layer 2 arranged in sequence from top to bottom.

[0056] Further, please refer to the attached Figure 5The heat shrinkable tube 6 can be used as the wrapping material outside the grating scale assembly A, and in this case, the second flexible adhesive layer 4 and the second insulating base layer 5 can be omitted.

[0057] Please refer to the drawings Figure 6 The wrapping part 7 can also be a C-shaped aluminum profile, and the upper side of the wrapping part 7 is open, and support segments 7a are formed on both ends of the open upper side and located above the grating strips 1. The support segments 7a can directly press the upper two ends of the grating strips 1. As shown in the drawings Figure 7 It can be seen that the support segments 7a can also press the upper two ends of the grating strips 1 through the glue-like filler 8, and the glue-like filler 8 is preferably a glue stick.

[0058] For example Figure 8 and 9 To facilitate the installation of the grating scale assembly A in the equipment, the first insulating base layer 2 is connected with a base plate 9 through a threaded fastener c, and the threaded fastener c is arranged between two adjacent grating strips 1a, and the threaded fastener c is located below the metal part of the grating strips 1 and is blocked by the metal segments 1b, so as not to affect the inductive value.

[0059] Finally, it should be noted that the above description is only a preferred embodiment of the present application, and those skilled in the art can make various similar modifications under the inspiration of the present application without departing from the purpose and scope of the present application. Such changes fall within the scope of the present application.

Claims

1. A sense grid type displacement sensor characterized by, The grid ruler assembly (A) and the induction head (B) are installed to the equipment to be measured, and the induction head (B) can move relative to the length direction of the grid ruler assembly (A); The grid ruler assembly (A) has a grid belt (1) which is provided with grids (1a) in the length direction, the grid (1a) is a through hole or a downward recessed groove structure, the induction head (B) is internally provided with at least two induction coils (a), when current is passed through the induction coil (a), mutual inductive electromotive force can be generated between each induction coil (a); During the movement of the induction head (B) along the length direction of the grid ruler assembly (A), the mutual inductive electromotive force between each induction coil (a) changes with the arrangement rule of the grid (1a).

2. The inductive displacement sensor of claim 1, wherein: The grid ruler assembly (A) comprises a first insulating base layer (2), and the grid belt (1) is connected to the upper side of the first insulating base layer (2) through a first flexible glue layer (3).

3. The inductive-sensor displacement sensor of claim 2, wherein: The upper side of the grid belt (1) is connected with a second insulating base layer (5) through a second flexible glue layer (4).

4. The inductive displacement sensor according to claim 1 or 2 or 3, characterized in that: The grid ruler assembly (A) is wrapped with a heat shrink tube (6) outside.

5. The inductive-sensor displacement sensor of claim 2, wherein: The grid ruler assembly (A) is provided with a wrapping component (7) outside, the wrapping component (7) is open at the upper side and is provided with a support section (7a) above the grid belt (1) at the positions corresponding to the two ends of the opening, and a glue-like filler (8) is arranged between the support section (7a) and the grid belt (1).

6. The inductive-sensor displacement sensor of claim 2, wherein: The bottom of the first insulating base layer (2) is connected with a base material plate (9) through a threaded fastener (c) or a riveting mode, and the threaded fastener (c) is arranged between two adjacent grids (1a) of the grid belt (1).

7. The inductive-sensor displacement sensor of claim 1, wherein: The induction head (B) comprises a shell (10) and a coil PCB board (11) fixedly arranged inside the shell (10), and the induction coil (a) is arranged on the coil PCB board (11).

8. The inductive-sensor displacement sensor of claim 1, wherein: Among the induction coils (a), one induction coil (a) is a rectangular frame-shaped primary coil, and the others are secondary coils, each secondary coil is a sinusoidal planar coil, and the secondary coils are sequentially arranged in the primary coil with a phase difference of 90°.

9. The inductive sensing displacement sensor of claim 8, wherein: The number of the secondary coils is 2 or 3 or 4.

10. The inductive displacement sensor of claim 8 or 9, wherein: The grid belt (1) is a metal grid belt, and a metal section (1b) is formed between two adjacent grids (1a), and the length ratio between the metal section (1b) and the grid (1a) is 3:

1.

11. The inductive sensing displacement sensor of claim 10, wherein: The total length of the metal section (1b) and the adjacent grid (1a) is 10.24mm or 5.12mm.

12. The inductive sensing displacement sensor of claim 9, wherein: At least two grid ruler assemblies (A) are arranged in parallel in space, and the number of the induction heads (B) corresponds to the number of the grid ruler assemblies (A).

13. The inductive sensing displacement sensor of claim 12, wherein: The planes of the two adjacent grid ruler assemblies (A) are arranged in parallel in space in a side-by-side parallel layout, a directly opposite parallel layout, an angle parallel layout or a vertical parallel layout.

14. The inductive sensing displacement sensor of claim 13, wherein: The two adjacent induction heads (B) are staggered, or a shielding plate (17) is arranged between the two adjacent induction heads (B).

15. A grating displacement sensor according to claim 12 or 13 or 14, characterised in that: The length of the metal section (1b) and the grid (1a) is a grid pitch period, and the grid pitch periods of the grid ruler assemblies (A) are different.

16. The inductive sensing displacement sensor of claim 1, wherein: The grid ruler assembly (A) is configured as a long strip structure or an arc structure or a circular structure. The grid ruler assembly (A) is configured as a long strip structure or an arc structure or a circular structure.

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