High-voltage-resistant LVDT (Linear Variable Differential Transformer) displacement sensor

Abstract

The invention relates to a high-voltage-resistant LVDT (Linear Variable Differential Transformer) displacement sensor, belonging to the technical field of displacement sensors. The end covers comprise the front end cover and the rear end cover which are located at the two ends of the shell respectively, holes are formed in the middle portions of the front end cover and the rear end cover, the rear end cover is connected with the cable, and the front end cover penetrates through the iron core. The framework is of a hollow I-shaped structure and is located in the shell, the hollow part of the framework is an iron core moving space, and a double-sealing structure is arranged at the front end of the framework and is used for sealing hydraulic oil entering from the position of the front end cover; the coil is wound on the framework, and a wire outlet end of the coil is welded with the cable; the sealing plug is fixedly connected to the rear end of the framework and used for sealing; the plug is fixedly connected to the rear end of the framework and used for extruding and fixing the sealing plug; and the gasket is positioned between the plug and the rear end cover and is used for axial clearance adjustment. A scheme for sealing the interior of the sensor is provided through a pressure environment source, a core coil of the sensor is protected through an O-shaped ring sealing structure, other structural parts are all of a universal structure, and generalization is facilitated.

Description

Technical Field

[0001] This invention relates to a high-pressure resistant LVDT displacement sensor, belonging to the field of displacement sensor technology. Background Technology

[0002] The most representative non-contact displacement sensor is the differential transformer (LVDT) displacement sensor, which is widely used in the measurement field due to its advantages such as frictionless measurement, unlimited mechanical life, high resolution, high reliability, and high accuracy. Through structural design, LVDT sensors can achieve miniaturization and high environmental adaptability. For LVDT sensors that need to operate in high-pressure hydraulic environments for extended periods, the reliability and high accuracy of their sealing structure design are fundamental guarantees for long-term reliable operation. The materials used for each component of the LVDT sensor, the pressure-resistant structural design, and the sealing method all affect the sensor's accuracy.

[0003] Currently, extensive research has been conducted both domestically and internationally on the high reliability of LVDT sensors under pressure environments. One traditional method involves mounting two LVDT displacement sensors inside a water jacket as described in the patent, with cooling water flowing through the jacket. The sensor housing is designed with a sealing structure, and the sensors are sealed to the water jacket using metal end face seals and sealing rings. However, while the cooling water ensures normal operation of the LVDT sensor measuring small displacements at high temperatures, the sensor's sensing magnet is connected to a vertical rod extending from the vessel body. This vertical rod is susceptible to deformation due to temperature variations, affecting the sensor's measurement accuracy. Another traditional method includes a high-temperature, high-pressure connecting component and a displacement detection component. A high-temperature, high-pressure resistant sealing ring is installed between the connecting component and the displacement detection component. The inner hole of the LVDT displacement sensor coil is designed with a pressure-bearing inner sleeve to prevent the sensor coil from being affected by high pressure. However, this method is complex, involves numerous assembly components, and has a large structural size. While adding a pressure-bearing inner sleeve to the coil's central hole can isolate the sensor from the hydraulic oil, the large air gap can affect product performance. Deformation of the pressure-bearing inner sleeve under pressure can also affect the sensor's measurement accuracy. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a high-pressure resistant LVDT displacement sensor that achieves internal structural sealing, can be completely immersed in a hydraulic environment, and will not damage the demodulation circuit.

[0005] The technical solution of this invention is: a high-voltage resistant LVDT displacement sensor, comprising:

[0006] case;

[0007] End caps, including front end caps and rear end caps, are located at both ends of the housing, with holes in the middle. The rear end cap is connected to the cable, and the front end cap passes through the iron core.

[0008] The skeleton is a hollow I-shaped structure located inside the shell. Its hollow part is the space for the iron core to move, and the front end is provided with a first double sealing structure to seal the hydraulic oil entering from the front cover position.

[0009] The coil is wound on the frame, and the lead end is welded to the cable.

[0010] The sealing plug is fixedly connected to the rear end of the frame for sealing purposes;

[0011] The screw plug is fixedly connected to the rear end of the frame and is used to compress and fix the sealing plug.

[0012] A gasket, located between the screw plug and the rear end cap, is used for axial clearance adjustment.

[0013] Furthermore, the first double-sealing structure includes an O-ring and a retaining ring. Two O-rings are arranged side by side, and a retaining ring is provided on the inner side of the outer O-ring to prevent the O-ring from being damaged by external pressure.

[0014] Furthermore, the shell is designed with stepped holes inside, and the front end of the frame is fixed at the step to reduce the stress on the frame.

[0015] Furthermore, the skeleton surface is sprayed with a non-metallic coating and covered with a polyimide film.

[0016] Furthermore, the rear end of the housing is provided with a flange structure, and the front end face of the flange structure is provided with a sealing ring structure. During assembly, the sealing ring structure is used to seal the oil, preventing the hydraulic oil from passing over the flange structure.

[0017] Furthermore, the end of the iron core is provided with a thread, which is used to connect a friction-reducing screw. The friction-reducing screw and the hollow part of the frame are in clearance fit to reduce the friction force on the iron core and protect the iron core.

[0018] Furthermore, the front end of the iron core is provided with a thread and a spherical bearing interface. The thread is used to connect external components, and the spherical bearing interface is used to adjust the radial angle of the iron core, reduce the stress on the threaded connection at the front end of the iron core, avoid fatigue fracture, and solve the damage caused by eccentric assembly of the iron core.

[0019] Furthermore, the sealing plug is provided with a second double-seal structure, which includes O-rings. Two O-rings are arranged side by side to prevent hydraulic oil from flowing into the demodulation circuit.

[0020] Furthermore, the material of the shell is titanium alloy TC4.

[0021] Furthermore, the material of the skeleton is elastic alloy 3J21.

[0022] The advantages of this invention compared to the prior art are:

[0023] 1. This invention provides a solution for sealing the inside of the sensor by utilizing a pressure environment source. The sensor core coil is protected by an O-ring sealing structure, while other structural components are of general-purpose type, which facilitates standardization.

[0024] 2. The present invention has a compact structure and is simple to assemble compared with sensors that use complex pressure-resistant structures. It can meet various high-pressure miniaturized and high-precision displacement measurement needs.

[0025] 3. This invention uses an internal radial sealing method to ensure that the core coil is not affected by high voltage. Compared with sensors that use welding sealing or outer tube opening, it has the characteristics of high reliability and long working life.

[0026] 4. Through a sealed structure design, the sensor lead cable is isolated from the high-pressure hydraulic oil, thus better ensuring the transmission of sensor signals.

[0027] 5. Through structural design, the iron core of this invention effectively reduces the instability of sensor performance and fatigue fracture at the threaded connection of the iron core caused by iron core wear due to iron core wear caused by iron core assembly eccentricity and small clearance fit.

[0028] 6. Through magnetic circuit design and winding design, this invention achieves high-precision measurement of long-stroke displacement in a confined assembly space, solving the problem of high-precision real-time measurement of large-stroke LVDTs. Attached Figure Description

[0029] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0030] Figure 1 This is a schematic diagram of a high-voltage LVDT.

[0031] Figure 2 This is a schematic diagram of the sealing structure. Detailed Implementation

[0032] To better understand the above technical solutions, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations on the technical solutions of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0033] The following description, in conjunction with the accompanying drawings, provides a more detailed account of a high-voltage LVDT displacement sensor provided by an embodiment of the present invention. Figure 1 The specific implementation may include: a housing 1; end caps, including a front end cap 3 and a rear end cap 9, located at both ends of the housing 1, with openings in the middle, the rear end cap 9 connecting to the cable, and the front end cap 3 passing through the iron core 7; a frame 8, a hollow I-shaped structure located inside the housing 1, the hollow part of which is the moving space of the iron core 7, and the front end is provided with a double sealing structure for sealing the hydraulic oil entering from the front end cap 3; a coil 2, wound on the frame 8, with the lead end welded to the cable; a sealing plug 4, fixedly connected to the rear end of the frame 8 for sealing; a screw plug 5, fixedly connected to the rear end of the frame 8 for pressing and fixing the sealing plug 4; and a gasket 6, located between the screw plug 5 and the rear end cap 9 for adjusting the axial clearance.

[0034] Furthermore, such as Figure 2 The double-sealing structure includes an O-ring 201 and a retaining ring 202. Two O-rings 201 are arranged side-by-side, with a retaining ring 202 inside the outer O-ring 201 to prevent damage from external pressure. The housing 1 has a stepped hole inside, and the front end of the frame 8 is fixed at the step to reduce stress on the frame 8. The rear end of the housing 1 has a flange structure with a sealing ring structure on its front end face. During assembly, the sealing ring structure provides a seal, preventing liquid from overflowing the flange structure. The end of the core 7 has a thread for connecting a friction-reducing screw. The friction-reducing screw and the hollow part of the frame 8 have a clearance fit to reduce friction on the core 7 and protect it. The front end of the core 7 has a thread and a spherical bearing interface. The thread is used to connect external components, and the spherical bearing interface is used to adjust the radial angle of the core 7, reducing stress at the threaded connection point and preventing fatigue fracture. It also addresses damage caused by misalignment during core 7 assembly.

[0035] In the solutions provided in the embodiments of the present invention, as shown in the appendix Figure 1 As shown, the typical basic components of the pressure-resistant LVDT displacement sensor of the present invention include a housing 1, a coil 2, end caps (front end cap 3 and rear end cap 9), a sealing plug 4, a screw plug 5, a gasket 6, an iron core 7, and a frame 8.

[0036] A double-seal structure is designed at the front end of the skeleton 8 to fit with the inner hole of the housing 1 to seal the hydraulic oil entering from the front cover 3 of the sensor. During operation, the product is subjected to a large oil pressure. Therefore, a retaining ring 202 structure is added to the rear end of the first O-ring 201 to ensure that the sealing ring will not be damaged due to the large external pressure.

[0037] A double-sealed sealing plug 4 is installed at the inner hole of the coil 2 outlet end and tightened with a screw plug 5 to seal the hydraulic oil entering from the sensor core 7.

[0038] After the coil 2 is wound, it is installed in the cavity inside the housing 1. The axial gap is eliminated by pressing the gasket 6 through the end cap 3 in the axial direction. The housing 1 has stepped holes inside, which fix the skeleton 8 at the step to reduce the force on the skeleton 8.

[0039] The skeleton 8 is made of metal. Although the commonly used metal film application method can improve the insulation performance, there will still be leakage points, which will lead to a decrease in insulation performance. Therefore, the skeleton 8 adopts the method of spraying non-metallic coating and applying polyimide film to ensure the insulation performance of the product.

[0040] The housing 1 has a flange structure at the cable outlet, and a sealing ring structure is designed at the front end of the flange structure. During assembly, the sealing ring is used to seal and ensure that liquid does not enter the decoding circuit through the sensor cable.

[0041] The iron core 7 has anti-friction screws designed on the outside of the threaded connection of the iron core. The anti-friction screws are fitted with the inner hole of the skeleton with a small clearance to reduce the friction force on the iron core and protect the iron core.

[0042] The front end of the core 7 is designed with a spherical bearing interface. The core is adjusted radially at a small angle through the spherical bearing, which effectively reduces the stress on the threaded connection of the core 7 and avoids fatigue fracture. At the same time, it solves the problem of core damage caused by eccentric assembly of the core 7.

[0043] In one possible implementation, the surface of the skeleton 8 is coated with a non-metallic coating and covered with a polyimide film. The sealing plug 4 has a double-sealing structure. The material of the housing 1 is titanium alloy TC4. The material of the skeleton 8 is elastic alloy 3J21.

[0044] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the novel technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection of the claims.

[0045] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0046] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A high-voltage resistant LVDT displacement sensor, characterized in that, include: Shell (1); The end caps, including the front end cap (3) and the rear end cap (9), are located at both ends of the housing (1), with holes in the middle. The rear end cap (9) is connected to the cable, and the front end cap (3) passes through the iron core (7). The skeleton (8) is a hollow I-shaped structure located inside the shell (1). Its hollow part is the space for the iron core (7) to move, and the front end is provided with a first double sealing structure to seal the hydraulic oil entering from the front cover (3). The coil (2) is wound on the frame (8), and the lead end is welded to the cable. The sealing plug (4) is fixedly connected to the rear end of the frame (8) for sealing; The screw plug (5) is fixedly connected to the rear end of the skeleton (8) and is used to compress and fix the sealing plug (4); A gasket (6) is located between the screw plug (5) and the rear end cap (9) for adjusting the axial clearance.

2. The high-voltage resistant LVDT displacement sensor according to claim 1, characterized in that, The first double-sealing structure includes an O-ring (201) and a retaining ring (202). The O-ring (201) is arranged in two parallel positions, and the outer O-ring (201) is provided with a retaining ring (202) on its inner side to prevent the O-ring (201) from being damaged by external pressure.

3. The high-voltage resistant LVDT displacement sensor according to claim 1, characterized in that, The shell (1) has a stepped hole inside, and the front end of the frame (8) is fixed at the step to reduce the force on the frame (8).

4. A high-voltage resistant LVDT displacement sensor according to claim 1, characterized in that, The skeleton (8) is coated with a non-metallic coating and then covered with a polyimide film.

5. A high-voltage resistant LVDT displacement sensor according to claim 1, characterized in that, The rear end of the housing (1) is provided with a flange structure, and the front end face of the flange structure is provided with a sealing ring structure. During assembly, the sealing ring structure is used to seal the liquid so that the liquid will not pass through the flange structure.

6. A high-voltage resistant LVDT displacement sensor according to claim 1, characterized in that, The iron core (7) has a thread at its end, which is used to connect a friction-reducing screw. The friction-reducing screw and the hollow part of the skeleton (8) are in clearance fit to reduce the friction force on the iron core (7) and protect the iron core (7).

7. A high-voltage resistant LVDT displacement sensor according to claim 6, characterized in that, The front end of the iron core (7) is provided with a thread and a spherical bearing interface. The thread is used to connect external components, and the spherical bearing interface is used to adjust the radial angle of the iron core (7), reduce the stress on the threaded connection at the front end of the iron core (7), avoid fatigue fracture, and solve the damage caused by the eccentric assembly of the iron core (7).

8. A high-voltage resistant LVDT displacement sensor according to claim 1, characterized in that, The sealing plug (4) is provided with a second double-seal structure, which includes an O-ring (401). The O-ring (401) is arranged in two parallel positions to prevent hydraulic oil from flowing into the demodulation circuit.

9. A high-voltage resistant LVDT displacement sensor according to claim 1, characterized in that, The material of the shell (1) is titanium alloy TC4.

10. A high-voltage resistant LVDT displacement sensor according to claim 1, characterized in that, The material of the skeleton (8) is elastic alloy 3J21.

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