A double-pull rod external magnetostrictive displacement sensor

Abstract

The present invention discloses a double-pull rod type external magnetostrictive displacement sensor, which is installed outside the oil cylinder when in use, and is used to accurately measure the bidirectional telescopic displacement of the oil cylinder. It can integrate two complete sets of hardware and software systems in a limited external space, and can integrate and output two independent signals, and has a separate power supply and signal output. The device has an extra-long working stroke. Through the above method, the present invention can be used in special occasions such as equipment with a long stroke, bidirectional displacement, two-stage displacement, military missions, etc., and is suitable for applications with high requirements for measurement stability and reliability and a long stroke, and solves the measurement problem of bidirectional telescopic extra-long oil cylinders.

Description

Technical Field

[0001] The invention relates to the technical field of displacement distance measurement, and in particular to a double-pull-rod type external magnetostrictive displacement sensor. Background Art

[0002] At present, magnetostrictive technology is widely used in military, petrochemical, machinery manufacturing, metallurgy, energy and other industries due to its high precision and reliability. The external magnetostrictive displacement sensor is a device installed on the outside of the oil cylinder when in use, used to accurately measure the telescopic displacement of the oil cylinder. The existing technology lacks products that can meet the high requirements of measurement stability or external magnetostrictive displacement sensors that cannot be replaced or easily replaced in special occasions such as ultra-long stroke, bidirectional telescopic displacement, two-stage telescopic displacement, and military missions. Summary of the invention

[0003] To this end, the present invention provides a double-pull rod external magnetostrictive displacement sensor to meet the needs of special occasions such as ultra-long stroke, bidirectional telescopic displacement, two-stage telescopic displacement, military missions, etc., where the measurement stability requirements are high or the external magnetostrictive displacement sensor cannot be replaced or easily replaced.

[0004] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: a double-pull rod type external magnetostrictive displacement sensor, the magnetostrictive displacement sensor comprising a shell, two groups of pull rod assemblies, two groups of end cover assemblies and two groups of circuit board assemblies, the pull rod assembly comprising a pull rod, the two groups of pull rods are slidably extended from the end of the shell into the interior of the shell, a group of end cover assemblies are respectively arranged between the pull rod and the end of the shell, the outer end of the pull rod is connected to the external cylinder piston rod, the inner end of the pull rod is provided with a magnet, two groups of circuit board assemblies are arranged inside the shell and correspond to the two groups of pull rod assemblies respectively, each group of circuit board assemblies comprises a waveguide wire arranged in parallel with the corresponding pull rod, and the magnetostrictive effect of the waveguide wire is used to monitor displacement.

[0005] Furthermore, two groups of pull rods extend into the shell from the same end of the shell, or two groups of pull rods extend into the shell from two ends of the shell respectively.

[0006] Furthermore, the pull rod assembly also includes a main slider, a secondary slider, a compression spring and a self-locking nut. The main slider is sleeved on the end of the pull rod. The main slider is provided with a first mounting groove for placing the self-locking nut. The main slider is fixed to the end of the pull rod by a threaded connection with the self-locking nut. The magnet is installed in the second mounting groove of the main slider. The secondary slider is sleeved on the pull rod and connected to the main slider through a compression spring.

[0007] Furthermore, the main slider and the auxiliary slider adopt a shuttle-shaped arc structure, and a slider guide rail matching the main slider and the auxiliary slider is formed on the shell.

[0008] Furthermore, a fisheye ball head bearing connecting rod is provided at the upper end of the pull rod, the fisheye ball head bearing connecting rod is connected to the fisheye ball head bearing through a thread, and the pull rod is connected to the external oil cylinder piston rod through the fisheye ball head bearing.

[0009] Furthermore, a slider connector for connecting the auxiliary slider is provided at the lower end of the pull rod, and a carbon fiber tube is provided on the outer side of the middle body of the pull rod, and the carbon fiber tube is connected between the fisheye ball head bearing connecting rod and the slider connector.

[0010] Furthermore, the circuit board assembly includes a circuit board sealing cover and a sensor element arranged in the circuit board sealing cover, the circuit board sealing cover contains electronic components and is sealed by glue pouring, and a circuit board sealing cover slot for fixing the circuit board sealing cover is formed on the shell, the sensor element includes a main board, a sub-board and a sensitive element, the main board and the sub-board are placed side by side and are connected to the sub-board through a circuit board bracket, the sensitive element includes a waveguide wire, a high-temperature wire, a coil, a central lead, a coil skeleton and a magnetic core, one end of the waveguide wire is bent 90 degrees and welded to the main board, and the other end is inserted into the sensitive element bracket column on the sensitive element bracket, and the sensitive element bracket is fixed to the main board by an M2 connecting screw, the high-temperature wire is placed side by side with the waveguide wire, one end of the high-temperature wire is wrapped around the waveguide wire, and the other end is welded to the main board, the central lead is placed vertically above the waveguide wire and placed in the coil skeleton, and one end of the central lead is welded to the waveguide wire.

[0011] Furthermore, a shielding device is provided on the outside of the sensitive element, and the shielding device includes a shielding tube and a shielding cover. The shielding cover is provided on the outside of the sensitive element body and one end of the shielding cover is welded to the main board, and the other end is fixedly connected to the copper base by an M2 connecting screw. The copper base is fixed to the main board by an M2 connecting screw. A glass fiber tube is provided on the outside of the extended section of the waveguide wire, and the glass fiber tube wraps the waveguide wire and extends into the shielding tube. One end of the shielding tube is welded to the copper base, and the other end is sealed. A shielding tube bracket is provided on the outside of the shielding tube, and the shielding tube bracket shares a slot with the circuit board sealing cover to realize the fixation of the circuit board assembly in the horizontal direction.

[0012] Furthermore, the end cover assembly includes an end cover, an end cover sealing gasket, a star-shaped sealing ring, a polytetrafluoroethylene gasket and a linear bearing. The end cover is fixed to the outer shell by an M4 hexagon socket bolt, an end cover sealing gasket is arranged between the end cover and the outer shell, a linear bearing for the pull rod to pass through is arranged inside the end cover, the bearing cover of the linear bearing is fixed by an M5 bolt, a polytetrafluoroethylene gasket is arranged at the lower end of the linear bearing, a star-shaped sealing ring is arranged below the polytetrafluoroethylene gasket, and the end cover is fixed to the circuit board by an M2 bolt to realize vertical fixation of the circuit board assembly.

[0013] Furthermore, an aviation plug is provided on the shell, and the circuit board assembly is connected to the aviation plug by a cable through circuit board leads to realize transmission of electrical signals, and a cable trough is formed on the shell.

[0014] The present invention has the following advantages:

[0015] The double-pull-rod external magnetostrictive displacement sensor proposed in the present invention has subversive advantages over ordinary magnetostrictive displacement sensors and pull-rod sensors. In addition to the advantages of compact structure, durability, linear measurement, high precision, and full-range adjustability of magnetostrictive displacement sensors, it also has the following revolutionary advantages because two pairs of magnetostrictive sensors are integrated internally to support bidirectional measurement: ultra-long travel, the maximum measurable single-pull-rod travel is 3 meters, and the total range can reach 9 meters; bidirectional measurement, when two sets of magnetostrictive displacement sensors facing each other are integrated internally, the displacement on both sides can be measured with the housing fixed. The oil cylinder or other equipment extended out can be accurately measured; two-stage telescopic measurement, under some special working conditions, the oil cylinder or other equipment needs to perform two-stage telescopic measurement, and most of the sensors currently used are draw-wire sensors, but the accuracy of draw-wire sensors is low and the failure rate is high. The present invention uses the magnetostrictive principle to achieve very high accuracy. At the same time, the design of the slider structure and materials and the selection of the pull rod material can greatly reduce the failure rate; same-direction measurement, when two sets of magnetostrictive displacement sensors located on the same side are integrated internally, it is possible to achieve accurate measurement of the oil cylinder or other equipment extended on the same side when the outer shell is fixed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0017] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0018] Figure 1 A schematic diagram of the structure of a double-pull-rod external magnetostrictive displacement sensor provided in Example 1 of the present invention;

[0019] Figure 2 A horizontal cross-sectional view of the internal structure of a double-pull-rod external magnetostrictive displacement sensor provided in Example 1 of the present invention;

[0020] Figure 3 A vertical cross-sectional view of the internal structure of a double-pull-rod external magnetostrictive displacement sensor provided in Example 1 of the present invention;

[0021] Figure 4 A cross-sectional view of a circuit board assembly of a double-pull-rod external magnetostrictive displacement sensor provided in Example 1 of the present invention;

[0022] Figure 5 A cross-sectional view of the housing of a double-pull-rod external magnetostrictive displacement sensor provided in Example 1 of the present invention;

[0023] Figure 6 A schematic diagram of the structure of a double-pull-rod external magnetostrictive displacement sensor slider provided in Example 1 of the present invention;

[0024] Figure 7 A cross-sectional view of an end cap assembly of a double-pull-rod external magnetostrictive displacement sensor provided in Example 1 of the present invention;

[0025] Figure 8 A cross-sectional view of a pull rod assembly of a double-pull rod type external magnetostrictive displacement sensor provided in Example 1 of the present invention.

[0026] In the figure: 1. Fisheye ball bearing; 2. Tie rod; 3. Bearing cover; 4. End cover; 5. Sealing pad; 6. Housing; 7. Air plug; 8. Auxiliary slider; 9. Compression spring; 10. Main slider; 11. Self-locking nut; 12. Magnet; 13. Circuit board sealing cover; 14. Star seal ring; 15. PTFE gasket; 16. M4 hexagon socket bolt; 17. Linear bearing; 18. M5 bolt; 19. Shielding tube; 20. Shielding tube bracket; 21. Shielding tube bracket; 22. Circuit board seal Cover slot; 23, slider guide; 24, cable duct; 25, fixed slot; 26, shuttle arc structure; 27, main board; 28, shielding cover; 29, waveguide wire; 30, sensitive element bracket column; 31, sensitive element bracket; 32, high-temperature wire; 33, M2 connecting screw; 34, copper base; 35, glass fiber tube; 36, M3 connecting screw; 37, circuit board bracket; 38, coil; 39, coil frame; 40, central lead; 41, magnetic core; 42, sub-board. DETAILED DESCRIPTION

[0027] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] like Figure 1 , Figure 2 and Figure 3 As shown, this embodiment proposes a double-pull rod type external magnetostrictive displacement sensor, which includes a housing 6, two groups of pull rod assemblies, two groups of end cover assemblies and two groups of circuit board assemblies. The pull rod assembly includes a pull rod 2, and the two groups of pull rods 2 are slidably extended into the interior of the housing 6 from the ends of the housing 6. In this embodiment, the two groups of pull rods 2 are respectively extended into the housing 6 from the two ends of the housing 6. A group of end cover assemblies are respectively arranged between the ends of the pull rod 2 and the housing 6, the outer end of the pull rod 2 is connected to the external oil cylinder piston rod, and a magnet 12 is arranged at the inner end of the pull rod 2. Two groups of circuit board assemblies are arranged inside the housing 6 and correspond to the two groups of pull rod assemblies respectively. Each group of circuit board assemblies includes a waveguide wire 29 arranged in parallel with the corresponding pull rod 2, and the magnetostrictive effect of the waveguide wire 29 is used to monitor displacement.

[0030] In this embodiment, Figure 8 As shown, the pull rod assembly also includes a main slider 10, a secondary slider 8, a compression spring 9 and a self-locking nut 11. The main slider 10 is sleeved on the end of the pull rod 2. Figure 6As shown, a first mounting groove for placing a self-locking nut 11 is provided on the main slider 10, and the main slider 10 is fixed by threading the self-locking nut 11 with the end of the pull rod 2, and the magnet 12 is installed in the second mounting groove of the main slider 10, and the auxiliary slider 8 is sleeved on the pull rod 2 and connected to the main slider 10 through a compression spring 9. The main slider 10 and the auxiliary slider 8 adopt a shuttle-shaped arc structure, and a slider guide 23 matching the main slider 10 and the auxiliary slider 8 is formed on the outer shell 6. The slider is made of ultra-high molecular weight polyethylene material, which is recognized as the most wear-resistant in the world. The slider adopts a shuttle-shaped arc structure, which can reduce the friction surface to the minimum size and solve the problem of the slider running jamming. Compression springs 9 are used to support the main and auxiliary sliders to further prevent the occurrence of jamming.

[0031] The upper end of the tie rod 2 is provided with a fisheye ball head bearing connecting rod 2-3, which is connected to the fisheye ball head bearing 1 through a thread, and the tie rod 2 is connected to the external cylinder piston rod through the fisheye ball head bearing 1. The lower end of the tie rod 2 is provided with a slider connector 2-1 for connecting the auxiliary slider 8, and the outer side of the middle body of the tie rod 2 is provided with a carbon fiber tube 2-2, which is connected between the fisheye ball head bearing connecting rod 2-3 and the slider connector 2-1.

[0032] In this embodiment, Figure 4 As shown, the circuit board assembly includes a circuit board sealing cover 13 and a sensor element arranged in the circuit board sealing cover 13. The circuit board sealing cover 13 contains electronic components and is sealed by glue filling. A circuit board sealing cover slot 22 for fixing the circuit board sealing cover 13 is formed on the shell 6. The sensor element includes a main board 27, a sub-board 42 and a sensitive element. The main board 27 and the sub-board 42 are placed side by side and are connected to the sub-board 42 through a circuit board bracket. The sensitive element includes a waveguide wire 29, a high-temperature wire 32, a coil 38, a central lead 40, a coil frame 39 and a magnetic core 41. The magnetic core 41 here is used to realize a strain pulse converter.

[0033] The shielding tube 19 is welded on the copper base 34, which is fixed on the main board 27. The waveguide wire 29 is inserted into the glass fiber tube 35 and inserted into the shielding tube 19 together with the high-temperature wire 32; the waveguide wire 29 penetrates the sensitive element bracket 31 and the sensitive element bracket column 30 and is welded to the main board 27; the coil 38, the coil skeleton 39, and the central lead 40 are placed perpendicular to the waveguide wire 29 on the sensitive element bracket 31, and one end of the central lead 40 is welded above the waveguide wire 29. The shielding cover 28 wraps the sensitive element bracket 31, the sensitive element bracket column 30, the magnetic core 41, the coil 38, the central lead 40, the coil skeleton 39, etc., and is welded on the main board 27 and fixed to the copper base 34 by screws. The main board 27 and the sub-board 42 are fixed and placed side by side by the circuit board bracket 37; the main board 27 and all electronic components are installed in the circuit board sealing cover 13 through the card slot; the shielding tube bracket 20 is used to support the shielding tube 19.

[0034] In this embodiment, Figure 7 As shown, the end cover assembly includes an end cover 4, a sealing gasket 5, a star-shaped sealing ring 14, a polytetrafluoroethylene gasket 15 and a linear bearing 17. The end cover 4 is fixed to the housing 6 by an M4 hexagon socket bolt 16. A sealing gasket 5 is arranged between the end cover 4 and the housing 6. A linear bearing 17 for the pull rod 2 to pass through is arranged inside the end cover 4. The bearing cover 3 of the linear bearing 17 is fixed by an M5 bolt 18. A polytetrafluoroethylene gasket 15 is arranged at the lower end of the linear bearing 17. A star-shaped sealing ring 14 is arranged below the polytetrafluoroethylene gasket 15. The polytetrafluoroethylene gasket 15 is used to seal the seal between the linear bearing 17 and the end cover 4, and the seal of the pull rod 2. The star-shaped sealing ring 14 is used to seal the pull rod 2. The sealing gasket 5 is used to seal between the end cover 4 and the housing 6. The bearing cover 3 is used to fix the linear bearing 17. The end cover 4 is fixed to the circuit board by an M2 bolt to realize the vertical fixation of the circuit board assembly.

[0035] like Figure 5 As shown, a fixing groove 25 is provided on the outer periphery of the housing 6 for fixing to the outside of the oil cylinder.

[0036] In this embodiment, an aviation plug 7 is provided on the housing 6 , and the circuit board assembly is connected to the aviation plug using a cable via circuit board leads to achieve transmission of electrical signals, and a cable trough 24 is formed on the housing 6 .

[0037] Measuring principle: During measurement, the electronic part of the sensor generates a current pulse. This current generates a magnetic field that moves along the waveguide wire 29. The magnet 12 on the slider also generates a magnetic field. When the magnetic field generated by the current intersects with the magnetic field generated by the magnet 12, the waveguide wire 29 produces a magnetostrictive effect and generates a strain pulse. This pulse is transmitted back along the waveguide wire 29 at a fixed speed and is detected by the measuring element. By measuring the time between the current pulse and the strain pulse, the position (displacement) of the magnet can be accurately determined.

[0038] The double pull rod assembly and circuit board assembly of this embodiment have independent power supply and signal output systems, and both systems can work independently regardless of primary and secondary. There are two working modes:

[0039] Bidirectional measurement mode: The housing 6 is fixed, and the two pull rods 2 move in opposite directions. The output signal types are exactly the same, which can realize independent and accurate measurement of single-channel signals, and also realize overall displacement measurement of the two pull rods 2. The overall stability and reliability of the system are higher.

[0040] Two-stage telescopic measurement mode: the pull rod 2 on one side is fixed by a fisheye ball bearing, the housing 6 moves as a whole, and then the pull rod 2 on the other side continues to move, which can be used for accurate measurement of the two-stage telescopic cylinder.

[0041] The double-pull rod external magnetostrictive displacement sensor of this embodiment has a disruptive advantage over ordinary magnetostrictive displacement sensors. In addition to the advantages of compact structure, durability, linear measurement, high precision, and full-range adjustability of magnetostrictive displacement sensors, the pull rods 2 on both sides can achieve precise measurement of special work and special equipment.

[0042] Example 2

[0043] The difference between this embodiment and the above-mentioned embodiment 1 is that the two sets of pull rods 2 can be arranged to extend from the same end of the housing 6 into the housing 6. Compared with the embodiment 1, the following working modes can be realized:

[0044] Same-direction measurement: When two sets of magnetostrictive displacement sensors located on the same side are integrated internally, it is possible to accurately measure the oil cylinder or other equipment extending on the same side while the housing 6 is fixed.

[0045] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A double-pull rod external magnetostrictive displacement sensor, characterized in that: The magnetostrictive displacement sensor comprises a housing, two groups of tie rod assemblies, two groups of end cover assemblies and two groups of circuit board assemblies. The tie rod assembly comprises tie rods. The two groups of tie rods are slidably extended from the ends of the housing into the interior of the housing. A group of end cover assemblies is respectively arranged between the ends of the tie rods and the housing. The outer ends of the tie rods are connected to the piston rods of the external oil cylinders. The inner ends of the tie rods are provided with magnets. Two groups of circuit board assemblies are arranged inside the housing and correspond to the two groups of tie rod assemblies respectively. Each group of circuit board assemblies comprises a waveguide wire arranged in parallel with the corresponding tie rod, and the magnetostrictive effect of the waveguide wire is used to perform displacement monitoring. Two sets of pull rods extend into the shell from two ends of the shell respectively; The pull rod assembly also includes a main slider, a secondary slider, a compression spring and a self-locking nut, wherein the main slider is sleeved on the end of the pull rod, and a first mounting groove for placing the self-locking nut is provided on the main slider, and the main slider is fixed to the end of the pull rod by threading with the self-locking nut, and the magnet is installed in the second mounting groove of the main slider, and the secondary slider is sleeved on the pull rod and connected to the main slider by the compression spring; The main slider and the auxiliary slider adopt a shuttle-shaped arc structure, and a slider guide rail matching the main slider and the auxiliary slider is formed on the shell.

2. A double-pull-rod external magnetostrictive displacement sensor according to claim 1, characterized in that: A fisheye ball head bearing connecting rod is arranged at the upper end of the pull rod, and the fisheye ball head bearing connecting rod is connected to the fisheye ball head bearing through a thread, and the pull rod is connected to the external oil cylinder piston rod through the fisheye ball head bearing.

3. A double-pull-rod external magnetostrictive displacement sensor according to claim 2, characterized in that: The lower end of the pull rod is provided with a slider connector for connecting the auxiliary slider, and the outer side of the middle body of the pull rod is provided with a carbon fiber tube, and the carbon fiber tube is connected between the fisheye ball head bearing connecting rod and the slider connector.

4. A double-pull-rod external magnetostrictive displacement sensor according to claim 1, characterized in that: The circuit board assembly includes a circuit board sealing cover and a sensor element arranged in the circuit board sealing cover, the sensor element includes a main board, a sub-board and a sensitive element, the main board is connected to the sub-board through a circuit board bracket, the sensitive element includes a waveguide wire, a high-temperature wire, a coil, a central lead, a coil frame and a magnetic core, one end of the waveguide wire is welded to the main board, and the other end is inserted into the sensitive element bracket column on the sensitive element bracket, the sensitive element bracket is fixed on the main board, one end of the high-temperature wire is wound around the waveguide wire, and the other end is welded to the main board, the central lead is placed vertically above the waveguide wire and placed in the coil frame, and one end of the central lead is welded to the waveguide wire.

5. A double-pull-rod external magnetostrictive displacement sensor according to claim 4, characterized in that: A shielding device is arranged on the outside of the sensitive element, and the shielding device includes a shielding tube and a shielding cover. The shielding cover is arranged on the outside of the main body of the sensitive element, and one end of the shielding cover is welded to the main board, and the other end is fixedly connected to the copper base, and the copper base is fixed to the main board. A glass fiber tube is arranged on the outside of the extended section of the waveguide wire, and the glass fiber tube wraps the waveguide wire and extends into the shielding tube. One end of the shielding tube is welded to the copper base, and the other end is sealed. A shielding tube bracket is arranged on the outside of the shielding tube, and the shielding tube bracket shares a slot with the circuit board sealing cover to realize the fixation of the circuit board assembly in the horizontal direction.

6. The double-pull-rod external magnetostrictive displacement sensor according to claim 1, characterized in that: The end cover assembly includes an end cover, an end cover sealing gasket, a star-shaped sealing ring, a polytetrafluoroethylene gasket and a linear bearing. The end cover is fixed to the outer shell, and an end cover sealing gasket is arranged between the end cover and the outer shell. A linear bearing for a pull rod to pass through is arranged inside the end cover, a polytetrafluoroethylene gasket is arranged at the lower end of the linear bearing, and a star-shaped sealing ring is arranged below the polytetrafluoroethylene gasket. The end cover is fixedly connected to the circuit board to realize vertical fixation of the circuit board assembly.

7. The double-pull-rod external magnetostrictive displacement sensor according to claim 1, characterized in that: An aviation plug is arranged on the shell, and the circuit board assembly is connected to the aviation plug by a cable through circuit board leads to realize transmission of electrical signals, and a cable trough is formed on the shell.

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