Closed annular driving sliding handle type LVDT facilitating zero position adjustment

Abstract

The utility model discloses a closed annular driving sliding handle type LVDT (Linear Variable Differential Transformer) convenient for zero position adjustment, which comprises a shell, a coil framework, a coil, an iron core, flexible pull rods, a sliding handle connecting seat, a distance adjusting cylinder, a pull rod connecting column and a locking sleeve, one end of each flexible pull rod is connected with the iron core, the middle part of the sliding handle connecting seat is connected with a sliding handle, and the other end of each flexible pull rod is connected with the corresponding distance adjusting cylinder. The two interval adjusting barrels are arranged outside the studs at the two ends of the sliding handle connecting base in a sleeving mode through the open ends of the interval adjusting barrels respectively, connecting column convex rings of the two pull rod connecting columns are arranged in the two interval adjusting barrels respectively, and the two pull rod connecting columns penetrate through adjusting barrel axial through holes in the middles of the closed ends of the two interval adjusting barrels respectively. The other ends of the two pull rod connecting columns are respectively connected with the two flexible pull rods, and the two locking sleeves are respectively sleeved outside the two pull rod connecting columns and are in threaded connection with the two pull rod connecting columns. According to the utility model, the function of high-precision zero adjustment after the assembly of the LVDT is completed is realized, the assembly efficiency is improved, and the high-precision application requirement is met.

Description

Technical Field

[0001] This utility model relates to a slide-type LVDT, and more particularly to a closed-ring drive slide-type LVDT that is easy to adjust to the zero position. Background Technology

[0002] LVDT is short for Linear Differential Transformer Displacement Sensor, a type of linear displacement sensor that uses the movement of an iron core to change the coil voltage to achieve displacement detection. It is widely used in shipbuilding, aviation, aerospace, and weaponry systems for controlling and feeding back linear displacement signals. The basic structure includes a housing and a cylindrical coil frame inside the housing, multiple coils wound on the coil frame, an iron core located within the coil frame, and a pull rod connected to the iron core. The coil typically includes a primary excitation coil and two secondary induction coils. During operation, an alternating current of a certain frequency is applied to the primary excitation coil, generating an induced voltage in the two secondary induction coils. When the pull rod moves the iron core, the induced voltage in the two secondary induction coils changes. By measuring the voltage difference between the two secondary induction coils, the positional change of the iron core can be obtained, thus achieving the purpose of linear displacement detection.

[0003] The slide-handle type LVDT is a linear differential transformer displacement sensor that uses a slide handle as the transmission component. The closed-ring drive slide-handle type LVDT is a relatively novel type of LVDT that the applicant has applied for and been granted. Its pull rod is an elastic pull rod (also called a flexible pull rod, which has a certain degree of elasticity, flexibility and can be bent and can realize the tension transmission relatively accurately). One end of the two elastic pull rods is connected to the two ends of the iron core respectively, and the other end of the two elastic pull rods is bent 180° and connected to the slide handle to form a closed-ring drive structure, so as to reduce the axial length of the product in the iron core. For the specific structure and working principle, please refer to the invention patent with patent number "ZL 202410105635.1" and title "Slide-handle type linear differential transformer displacement sensor".

[0004] In practical applications, we found the following defects in the aforementioned closed-ring driven sliding LVDT: Because the elastic rod is directly connected to the sliding handle, there is no structure to adjust the relative distance between them. Therefore, zero-position adjustment cannot be achieved after sensor assembly; it can only be adjusted during assembly. However, in practical applications, it is difficult to achieve precise zero-position adjustment during assembly. Only reliable zero-position adjustment after assembly can achieve higher zero-position adjustment accuracy. Therefore, the aforementioned closed-ring driven sliding LVDT cannot achieve high-precision zero-position adjustment, making it difficult to meet the requirements of high-precision applications. Furthermore, the elastic rod of the aforementioned closed-ring driven sliding LVDT is not easily threaded, and it is connected to both the sliding handle and the iron core using adhesive bonding. This connection method has low reliability, and to ensure smooth sliding, there is a gap between the elastic guide rod and the outer shell, which prevents the displacement of the sliding handle from being accurately transmitted to the iron core, reducing detection accuracy. Utility Model Content

[0005] The purpose of this invention is to provide a closed-ring drive slide-type LVDT that has a distance adjustment structure between the elastic pull rod and the slide to facilitate the adjustment of the zero position in order to solve the above problems.

[0006] This utility model achieves the above objectives through the following technical solutions:

[0007] A closed-loop driven slider-type LVDT for easy zero-position adjustment includes a housing and a cylindrical coil frame placed inside the housing, multiple coils wound on the coil frame, an iron core disposed within the coil frame, and flexible pull rods. One end of each of the two flexible pull rods is connected to both ends of the iron core, and the other ends of each of the two flexible pull rods are connected to the inner end of a slider. The outer end of the slider passes through a corresponding strip-shaped through hole on the housing and is located outside the housing. The closed-loop driven slider-type LVDT for easy zero-position adjustment also includes a slider connecting seat, a spacing adjustment cylinder, a pull rod connecting post, and a locking sleeve. The middle part of the slider connecting seat is connected to the inner end of the slider, and studs are respectively provided at both ends of the slider connecting seat. One end of the spacing adjustment cylinder is closed, and the other end is open. The inner circumference of the spacing adjusting cylinder is provided with internal threads. The two spacing adjusting cylinders are respectively fitted onto the studs at both ends of the sliding handle connecting seat through their open ends and are threaded together. The closed end of the spacing adjusting cylinder is provided with an axial through hole. The outer circumference of the pull rod connecting column is provided with external threads. One end of the pull rod connecting column is provided with a connecting column protrusion ring protruding outward. The connecting column protrusion rings of the two pull rod connecting columns are respectively placed in the inner cavities of the two spacing adjusting cylinders and the two pull rod connecting columns respectively pass through the axial through holes of the two adjusting cylinders. The other ends of the two pull rod connecting columns are respectively connected to the two flexible pull rods. The inner circumference of the tubular and axially penetrating locking sleeve is provided with internal threads. The two locking sleeves are respectively fitted onto the two pull rod connecting columns and are threaded together.

[0008] Preferably, to achieve a more reliable threaded connection while meeting both strength and flexibility requirements, the flexible pull rod is a polytetrafluoroethylene (PTFE) rod. The flexible pull rod is threaded to the iron core, and one end of the pull rod connecting post that connects to the flexible pull rod has an internal threaded hole, through which it is threaded to the corresponding flexible pull rod. PTFE material has inherent lubricating properties, so the gap between the flexible pull rod and the inner wall of the outer shell can be designed to be smaller, thereby achieving higher detection accuracy. Simultaneously, the outer circumference of the PTFE rod facilitates the installation of external threads.

[0009] Preferably, in order to achieve the threaded connection function between the flexible tie rod and the tie rod connecting post without increasing the space occupied, the outer diameter of the end of the flexible tie rod closest to the corresponding tie rod connecting post is reduced to form a tie rod small diameter section, and the tie rod small diameter section is connected to the corresponding tie rod connecting post.

[0010] Preferably, in order to facilitate the rotation of the spacing adjustment cylinder and the locking sleeve by a tool in a confined space to achieve the threaded connection and locking function, the cylinder wall of the spacing adjustment cylinder is provided with a plurality of radial through holes distributed circumferentially for rotating the spacing adjustment cylinder, and the tube wall of the locking sleeve is provided with a plurality of radial through holes distributed circumferentially for rotating the locking sleeve.

[0011] Preferably, in order to achieve a reliable connection between the slide block connecting seat and the slide block, the slide block connecting seat is provided with a screw hole in the middle and the inner end of the slide block is provided with an external thread and connected to the screw hole.

[0012] Preferably, in order to avoid the spacing adjustment cylinder from contacting the slide handle and affecting the connection reliability between the components, the outer diameter of the studs at both ends of the slide handle connecting seat is smaller than the outer diameter or width of the middle part of the slide handle connecting seat, and a step is formed at the transition position to prevent the corresponding spacing adjustment cylinder from continuing to approach the middle part of the slide handle connecting seat.

[0013] The beneficial effects of this utility model are as follows:

[0014] This invention achieves high-precision zero-position adjustment after LVDT assembly by adding a spacing adjustment device, including a sliding handle connecting seat, a spacing adjustment cylinder, a tie rod connecting column, and a locking sleeve, between the inner end of the sliding handle and the flexible tie rod. This reduces the requirements for zero-position adjustment accuracy during assembly, improves assembly efficiency, and meets the needs of high-precision applications. Attached Figure Description

[0015] Figure 1 This is a front sectional view of the closed-ring drive slide LVDT of this utility model, which is easy to adjust to the zero position;

[0016] Figure 2 yes Figure 1 Enlarged image of the letter "A" in the image;

[0017] Figure 3 This is a front sectional view of the flexible tie rod connection structure in the closed-ring drive slide-type LVDT that facilitates zero-position adjustment, as described in this utility model.

[0018] Figure 4 This is a perspective view of the flexible pull rod, slide, and spacing adjustment device of the closed-ring drive slide-type LVDT that is easy to adjust to the zero position, as described in this utility model, before assembly. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings:

[0020] like Figure 1-Figure 4As shown, the closed-ring drive slide-handle LVDT of this utility model, which facilitates zero-position adjustment, includes a housing 1 and a cylindrical coil frame 5 placed inside the housing 1, multiple coils 6 wound on the coil frame 5, an iron core 9 disposed inside the coil frame 5, and flexible pull rods 2. One end of each of the two flexible pull rods 2 is connected to both ends of the iron core 9, and the other end of each of the two flexible pull rods 2 is connected to the inner end of a slide handle 8. The outer end of the slide handle 8 passes through the corresponding strip-shaped through hole on the housing 1 and is placed outside the housing 1. The closed-ring drive slide-handle LVDT of this utility model, which facilitates zero-position adjustment, also includes a slide handle connecting seat 10, a pitch adjusting cylinder 12, a pull rod connecting post 15, and a locking sleeve 16. The middle part of the slide handle connecting seat 10 is connected to the inner end of the slide handle 8, and both ends of the slide handle connecting seat 10 are respectively provided with studs (not marked in the figure). One end of the pitch adjusting cylinder 12 is closed, and the other end is closed. The two pitch adjusting cylinders 12 are respectively fitted onto the studs at both ends of the sliding handle connecting seat 10 through their open ends and are threaded together. The closed end of the pitch adjusting cylinder 12 is provided with an axial through hole (not marked in the figure). The outer circumference of the pull rod connecting column 15 is provided with an external thread. One end of the pull rod connecting column 15 is provided with a connecting column protrusion ring 13 protruding outward in the circumferential direction. The connecting column protrusion rings 13 of the two pull rod connecting columns 15 are respectively placed in the inner cavity 11 of the two pitch adjusting cylinders 12 and the two pull rod connecting columns 15 pass through the two axial through holes of the adjusting cylinders respectively. The other end of the two pull rod connecting columns 15 is respectively connected to the two flexible pull rods 2. The inner circumference of the tubular and axially penetrating locking sleeve 16 is provided with an internal thread. The two locking sleeves 16 are respectively fitted onto the two pull rod connecting columns 15 and are threaded together.

[0021] like Figure 1-Figure 4 As shown, this utility model also discloses the following more optimized specific structures:

[0022] To achieve a more reliable threaded connection while meeting both strength and flexibility requirements, the flexible pull rod 2 is made of polytetrafluoroethylene (PTFE). The flexible pull rod 2 is threaded to the iron core 9, and threadlocker is preferably applied to the connecting threads. The end of the pull rod connecting post 15 that connects to the flexible pull rod 2 has an internal threaded hole, through which it is threaded to the corresponding flexible pull rod 2, and threadlocker is preferably applied to the connecting threads. PTFE material has inherent lubricating properties, so the gap between the flexible pull rod 2 and the inner wall of the outer shell 1 can be designed to be smaller, thereby achieving higher detection accuracy. Simultaneously, the outer circumference of the PTFE rod facilitates the installation of external threads.

[0023] In order to achieve the threaded connection between the flexible tie rod 2 and the tie rod connecting post 15 without increasing the space occupied, the outer diameter of the end of the flexible tie rod 2 closest to the corresponding tie rod connecting post 15 is reduced to form a tie rod minor diameter section 7, which is connected to the corresponding tie rod connecting post 15.

[0024] To facilitate the rotation of the pitch adjusting cylinder 12 and the locking sleeve 16 in a confined space using tools to achieve threaded connection and locking functions, the cylinder wall of the pitch adjusting cylinder 12 is provided with multiple radial through holes 14 distributed circumferentially for rotating the pitch adjusting cylinder 12, and the tube wall of the locking sleeve 16 is provided with multiple radial through holes 17 distributed circumferentially for rotating the locking sleeve 16.

[0025] In order to achieve a reliable connection between the slide connecting seat 10 and the slide 8, the slide connecting seat 10 is provided with a screw hole in the middle and the inner end of the slide 8 is provided with an external thread and connected to the screw hole.

[0026] In order to avoid the spacing adjustment cylinder 12 from contacting the slide handle 8 and affecting the connection reliability between the components, the outer diameter of the studs at both ends of the slide handle connecting seat 10 is smaller than the outer diameter or width of the middle part of the slide handle connecting seat 10, and a step is formed at the transition position to prevent the corresponding spacing adjustment cylinder 12 from continuing to approach the middle part of the slide handle connecting seat 10.

[0027] Figure 1 and Figure 3 The image also shows a pulley 4 installed inside the housing 1 to support the flexible tie rod 2. Figure 1 The image also shows the bearing 3 used to mount the pulley 4, both of which are of conventional structure.

[0028] like Figure 1-Figure 4 As shown, after the product is assembled, both locking sleeves 16 are located on the two pull rod connecting posts 15 at positions not in contact with the corresponding ends of the two pitch adjusting cylinders 12. High-precision zero-position adjustment is performed as follows: First, fix the slide handle 8 at the mechanical zero position in the middle of the housing 1 and observe the output voltage. If the output voltage is zero, it indicates that zero-position adjustment is not needed, but this is generally unlikely. If the output voltage is positive, first loosen the two locking sleeves 16, and then rotate the first (or second, depending on the relationship between the position of the iron core 9 and the output voltage, the same below) pitch adjusting cylinder 12 away from the slide handle connecting seat. Move the first (or second) pitch adjusting cylinder 12 in the direction of 10, and then (slightly delayed, almost simultaneously) rotate the second (or first) pitch adjusting cylinder 12 to move it closer to the sliding handle connecting seat 10. At this time, the iron core 9 is moved. Observe the change in output voltage until the output voltage is zero, which indicates that the mechanical zero position and the electrical zero position are accurately corresponding. Then tighten the two locking sleeves 16 to form a reliable hard connection structure between the pull rod connecting column 15 and the corresponding pitch adjusting cylinder 12, so as to avoid the gap at the connection affecting the transmission accuracy. This completes the high-precision zero position adjustment function. If the output voltage is negative, the adjustment method is similar, but the rotation direction of the two pitch adjusting cylinders 12 is opposite. The specific process will not be described in detail.

[0029] During operation, an alternating current of a certain frequency is applied to the primary excitation coil in coil 6. A certain induced voltage is generated in the first-stage induction coil and the second-stage induction coil in coil 6. The sliding handle 8 is connected to the moving part of the device under test. The moving part drives the sliding handle 8 to move linearly. The sliding handle 8 drives the flexible pull rod 2 to move synchronously. The flexible pull rod 2 passes around the pulley 4 to achieve bending movement and pulls the iron core 9 to move synchronously. The induced voltage of the first-stage induction coil and the second-stage induction coil will change. By measuring the voltage difference between the first-stage induction coil and the second-stage induction coil, the position change information of the iron core 9 can be obtained, thereby achieving the purpose of linear displacement detection of the moving part.

[0030] The above embodiments are merely preferred embodiments of this utility model and are not intended to limit the technical solutions of this utility model. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of this utility model patent.

Claims

1. A closed-loop drive slide-type LVDT with easy zero-position adjustment, comprising a housing and a cylindrical coil frame placed inside the housing, multiple coils wound on the coil frame, an iron core disposed within the coil frame, and flexible pull rods, wherein one end of each of the two flexible pull rods is connected to both ends of the iron core, and the other end of each of the two flexible pull rods is connected to the inner end of a slide handle, and the outer end of the slide handle passes through a corresponding strip-shaped through hole on the housing and is located outside the housing, characterized in that: The closed-ring drive slide-type LVDT with easy zero-position adjustment further includes a slide connecting seat, a spacing adjusting cylinder, a pull rod connecting post, and a locking sleeve. The middle part of the slide connecting seat is connected to the inner end of the slide handle. Studs are respectively provided at both ends of the slide connecting seat. One end of the spacing adjusting cylinder is closed, and the other end is open. Internal threads are provided on the inner circumference of the spacing adjusting cylinder. Two spacing adjusting cylinders are respectively fitted onto the studs at both ends of the slide connecting seat through their open ends and threadedly connected. An axial passage for adjusting the cylinder is provided in the middle of the closed end of the spacing adjusting cylinder. The tie rod connecting column has an external thread on its outer circumference. One end of the tie rod connecting column has a connecting column protruding in the outward direction. The connecting column protrusions of the two tie rod connecting columns are respectively placed in the inner cavities of the two spacing adjusting cylinders, and the two tie rod connecting columns pass through the axial through holes of the two adjusting cylinders. The other ends of the two tie rod connecting columns are respectively connected to the two flexible tie rods. The inner circumference of the tubular and axially penetrating locking sleeve has an internal thread. The two locking sleeves are respectively fitted on the outside of the two tie rod connecting columns and are threaded together.

2. The closed-ring drive slide type LVDT with easy zero-position adjustment according to claim 1, characterized in that: The flexible tie rod is a polytetrafluoroethylene (PTFE) rod, and the flexible tie rod is connected to the iron core by a thread. The end of the tie rod connecting post that is connected to the flexible tie rod is provided with an internal threaded hole, and the flexible tie rod is threadedly connected to the corresponding flexible tie rod through the internal threaded hole.

3. The closed-ring drive slide-type LVDT with easy zero-position adjustment according to claim 1 or 2, characterized in that: The outer diameter of the flexible tie rod is reduced at the end closest to the corresponding tie rod connecting post to form a small diameter section of the tie rod, and the small diameter section of the tie rod is connected to the corresponding tie rod connecting post.

4. The closed-ring drive slide-type LVDT with easy zero-position adjustment according to claim 1 or 2, characterized in that: The wall of the spacing adjusting cylinder is provided with a plurality of radial through holes distributed along the circumference for rotating the spacing adjusting cylinder, and the wall of the locking sleeve is provided with a plurality of radial through holes distributed along the circumference for rotating the locking sleeve.

5. The closed-ring drive slide-type LVDT with easy zero-position adjustment according to claim 1 or 2, characterized in that: The slide block connector has a screw hole in the middle and the inner end of the slide block has an external thread that connects to the screw hole.

6. The closed-ring drive slide-type LVDT with easy zero-position adjustment according to claim 1 or 2, characterized in that: The outer diameter of the studs at both ends of the slide block connector is smaller than the outer diameter or width of the middle part of the slide block connector, and a step is formed at the transition position to prevent the corresponding spacing adjustment cylinder from continuing to approach the middle part of the slide block connector.

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