Inductive contactless displacement sensor

Abstract

The application relates to an inductive contact type displacement sensor. The inductive contact type displacement sensor comprises a collection assembly, a shell assembly and a temperature-resistant assembly, the shell assembly comprises a shell, the collection assembly is arranged on the shell, a through hole is arranged on the shell, and the temperature-resistant assembly is embedded in the through hole. The scheme provided by the application can solve the problems of zero point drift and low resolution caused by structural looseness due to thermal expansion and cold shrinkage.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to an inductive contact displacement sensor. Background Technology

[0002] Inductive contact displacement sensors achieve non-contact measurement of displacement by having the object being measured move the magnetic core or magnetically conductive component within the coil, causing a change in the coil's inductance. This change is then combined with an oscillation circuit to output a corresponding frequency or electrical signal.

[0003] In related technologies, existing sensors typically use a plastic housing as the main structure to meet electrical performance requirements. To enhance installation strength and high-temperature resistance, an external metal shell or metal bracket is usually added for enclosure or semi-enclosure and fixation. Although this design improves mechanical strength and heat resistance, it can easily lead to loosening gaps between the metal parts and the plastic housing under long-term high and low temperature cycling conditions, resulting in zero-point drift and low resolution of the sensor. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an inductive contact displacement sensor that can solve the problems of zero-point drift and low resolution caused by structural loosening due to thermal expansion and contraction.

[0005] The objective of this invention is achieved through the following technical solution: The first aspect of this application provides an inductive contact displacement sensor, including a data acquisition component; a housing assembly, including a housing, wherein the data acquisition component is disposed on the housing; and a heat-resistant component, wherein the housing has a through hole, and the heat-resistant component is embedded in the through hole.

[0006] The temperature-resistant component includes a disc and a plug-in block. The disc is disposed on the plug-in block. After the plug-in block is embedded in the through hole, the disc fits into the housing.

[0007] The plug block is provided with an anti-rotation groove.

[0008] The housing assembly also includes a cover disposed on the housing.

[0009] The housing assembly also includes a frustum disposed within the through hole.

[0010] The housing assembly also includes screws, which are disposed in the through hole and pass through the plug block and the disc in sequence, and then abut against the frustum.

[0011] The housing assembly further includes a fixing block, which is disposed on the housing and has a first clearance hole and a second clearance hole.

[0012] The acquisition component includes a circuit board and a trigger, which are respectively disposed within the housing. The trigger is located on one side of the circuit board and includes a temperature-resistant measuring rod, a magnetic core, a frameless coil, and a spring. The housing assembly also includes a snap-fit ​​post with a clearance hole communicating with a first clearance hole. The temperature-resistant measuring rod partially protrudes outside the first clearance hole. A first end of the magnetic core is connected to the temperature-resistant measuring rod, and a second end of the magnetic core passes through the first clearance hole and the clearance hole in sequence. The frameless coil is disposed on the snap-fit ​​post, and the spring is disposed within the clearance hole. The second end of the magnetic core is connected to the spring, which is located on the circuit board. The trigger includes a wire harness disposed on the circuit board, and the extension direction of the wire harness intersects with or is parallel to the length direction of the cover.

[0013] The housing assembly further includes a cable outlet block, which is disposed on the housing, and the cable harness is disposed on the cable outlet block.

[0014] Compared with the prior art, the present invention has at least the following advantages: This application abandons the traditional enclosed or semi-enclosed metal casing, embedding a heat-resistant component into the casing as a mounting and positioning part, separating the casing from the product under test. Heat is not directly conducted to the casing, increasing its thermal deformation temperature. This solves the problems of zero-point drift and low resolution caused by structural loosening due to thermal expansion and contraction. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below.

[0016] Figure 1 This is a schematic diagram of the structure of an inductive contact displacement sensor according to an embodiment of the present invention; Figure 2 This is a schematic diagram of another embodiment of the inductive contact displacement sensor according to one embodiment of the present invention; Figure 3 This is a schematic diagram of another embodiment of the inductive contact displacement sensor according to one embodiment of the present invention; Figure 4 This is a schematic diagram of another embodiment of the inductive contact displacement sensor according to one embodiment of the present invention; Figure 5 This is a schematic diagram of another embodiment of the inductive contact displacement sensor according to one embodiment of the present invention; Figure 6 This is a circuit diagram of an inductive contact displacement sensor according to an embodiment of the present invention. Detailed Implementation

[0017] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0018] It should be understood that although the terms "first," "second," "third," etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0019] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0020] Inductive contact displacement sensors achieve non-contact measurement of displacement by having the object being measured move the magnetic core or magnetically conductive component within the coil, causing a change in the coil's inductance. This change is then combined with an oscillation circuit to output a corresponding frequency or electrical signal.

[0021] Currently, existing sensors typically use plastic housings as the main structure to meet electrical performance requirements. To enhance installation strength and high-temperature resistance, an external metal shell or metal bracket is usually added for enclosure or semi-enclosure and fixation. Although this design improves mechanical strength and heat resistance, it can easily lead to loosening gaps between the metal parts and the plastic housing during long-term high and low temperature cycling, resulting in zero-point drift and low resolution of the sensor.

[0022] To address the aforementioned issues, this application provides an inductive contact displacement sensor that can solve the problems of zero-point drift and resolution degradation caused by structural loosening due to thermal expansion and contraction.

[0023] The technical solutions of the embodiments of this application are described in detail below with reference to the accompanying drawings.

[0024] See Figure 1 and Figure 2 An inductive contact displacement sensor includes a data acquisition component 100, a housing component 200, and a temperature-resistant component 300. The housing component 200 includes a housing 210, and the data acquisition component 100 is disposed on the housing 210. A through hole 211 is provided on the housing 210, and the temperature-resistant component 300 is embedded in the through hole 211.

[0025] It should be noted that the acquisition component 100 is used to acquire the displacement of the product under test, and the housing component 200 is used to install the heat-resistant component 300 and the acquisition component 100. The heat-resistant component 300 is embedded in the through hole 211. Specifically, the material of the heat-resistant component 300 can be metal, ceramic, or other high-temperature materials. This application abandons the traditional enclosed or semi-enclosed metal housing, embedding the heat-resistant component 300 on the housing 210 as a mounting and positioning part, separating the housing 210 from the product under test. Heat is not directly conducted to the housing 210, and the temperature of the housing 210 can remain relatively constant. This solves the problem of zero-point drift and resolution reduction caused by structural loosening due to thermal expansion and contraction. In addition, there is a gap between the heat-resistant component 300 and the acquisition component 100, so even if the heat-resistant component 300 is magnetized, it will not affect the overall performance of the sensor.

[0026] See Figure 2 In one embodiment, the heat-resistant component 300 includes a disc 310 and a plug block 320. The disc 310 is disposed on the plug block 320. After the plug block 320 is embedded in the through hole 211, the disc 310 is attached to the housing 210.

[0027] It should be noted that the temperature-resistant component 300 of this application comprises, but is not limited to, two parts: a disc 310 and a connector block 320. The disc 310 is used to contact the product under test. The product under test includes, but is not limited to, the heating plate of an electric pressure cooker. The disc 310 and the connector block 320 are integrally formed. The disc 310 isolates the housing 210 from the directly heating part of the product under test, preventing heat from being directly conducted to the housing 210, thus maintaining a relatively constant temperature for the housing 210. This solves the problem of zero-point drift and resolution degradation caused by structural loosening due to thermal expansion and contraction. Furthermore, the installation of the temperature-resistant component 300 is very simple; it can be directly embedded into the through hole 211.

[0028] It should also be noted that other components, such as heat insulation sheets, can be added between the disc 310 and the housing 210.

[0029] See Figure 2In one embodiment, the plug block 320 is provided with an anti-rotation groove 321.

[0030] It is understandable that while heat-resistant materials can withstand high temperatures, significant thermal stress will arise within them due to thermal expansion and contraction during high and low temperature cycles. The anti-rotation groove 321 effectively provides a buffer space for expansion and contraction within the material, dispersing stress concentration areas and preventing stress accumulation. Furthermore, the anti-rotation groove 321 significantly increases the contact area between the material and air, creating an air convection channel to accelerate heat dissipation and prevent the sensor's resolution from decreasing due to overheating under high-temperature conditions. The anti-rotation groove also prevents the connector block 320 from rotating within the through hole 211.

[0031] See Figure 2 In one embodiment, the housing assembly 200 further includes a cover 220 disposed on the housing 310.

[0032] It is understandable that after the acquisition component 100 is assembled into the housing 310, the cover 320 will seal the entire housing 210.

[0033] See Figure 4 In one embodiment, the housing assembly 200 further includes a frustum 230 disposed within the through hole 211.

[0034] See Figure 2 and Figure 5 In one embodiment, the housing assembly 200 further includes a screw 240, which is disposed in the through hole 211 and passes through the plug block 320 and the disc 310 in sequence before abutting against the frustum 230.

[0035] It should be noted that during installation, this application only requires inserting the screw 240 into the connector 320 and tightening it. The screw 240 directly bears the force on the connector 320 and the disc 310, thus fixing the sensor. Therefore, thermal expansion and contraction do not affect the stability of the sensor.

[0036] See Figure 2 In one embodiment, the acquisition component 100 includes a circuit board 110 and a trigger 120, which are respectively disposed in the housing 210, with the trigger 120 located on one side of the circuit board 110.

[0037] It should be noted that, Figure 6 The circuit diagram of this application shows that a change in inductance occurs inside the trigger 120, which, combined with the LC oscillation circuit on the circuit board 110, outputs a linear voltage signal or digital signal. The circuit board 110 is located away from heat sources, making the output voltage signal or digital signal more stable.

[0038] Specifically, an MCU is set on the circuit board 110. The LC oscillation frequency after frequency division is directly sent to the MCU's IO port. The frequency of the input square wave is measured by the preset MCU, and then the output of a PWM wave with a duty cycle linearly related to the frequency is controlled by the software algorithm. Finally, the PWM wave is restored to a smooth DC voltage by an analog low-pass filter.

[0039] More specifically, this application can also define the MCU as an I2C slave device, which does not simply forward signals, but completes the entire process from frequency measurement and data processing to standard protocol response, realizing the "plug and play" of the sensor and making it more digital.

[0040] See Figure 1 and Figure 3 In one embodiment, the trigger 120 includes a wiring harness 121 disposed on the circuit board 110, and the extension direction of the wiring harness 121 intersects the length direction of the cover 320.

[0041] It should be noted that this application allows the extension direction of the wire harness 121 to be parallel to the length direction of the cover 320, which can reduce the overall height of the sensor, thereby reducing the height of the product under test and making the overall design more compact. Alternatively, the extension direction of the wire harness 121 can be perpendicular to or at a certain angle to the length direction of the cover 320, also for the purpose of further miniaturization.

[0042] See Figure 1 In one embodiment, the housing assembly 200 further includes a cable outlet block 250 disposed on the housing 210, and the wire harness 121 disposed on the cable outlet block 250.

[0043] It is understandable that the wire outlet block 250 is used to limit the wire harness 121, so that the angle and direction of the wire outlet are more uniform.

[0044] See Figure 2In one embodiment, the housing assembly 200 further includes a fixing block 260, which is disposed on the housing 210 and has a first clearance hole 261 and a second clearance hole 262. The trigger 120 also includes a temperature-resistant measuring rod 122, a magnetic core 123, a frameless coil 124, and a spring 125. The housing assembly 200 also includes a snap-fit ​​post 270, which has a clearance hole 271 that communicates with a first clearance hole 261. The temperature-resistant measuring rod 122 is partially exposed outside the first clearance hole 261. The first end of the magnetic core 123 is connected to the temperature-resistant measuring rod 122, and the second end of the magnetic core 123 passes through the first clearance hole 261 and the clearance hole 271 in sequence. The frameless coil 124 is disposed on the snap-fit ​​post 270, and the spring 125 is disposed inside the clearance hole 271. The second end of the magnetic core 123 is connected to the spring 125, and the spring 125 is located on the circuit board 110.

[0045] It should be noted that after the product under test comes into contact with the temperature measuring rod 122, the spring 125 deforms, causing the magnetic core 123 to move within the area of ​​the frameless coil 124, resulting in a change in inductance.

[0046] As is well known, the resolution of a sensor refers to the smallest change in the input physical quantity that the sensor can stably and accurately distinguish. It directly reflects the sensor's ability to perceive minute signals and is one of the core indicators for measuring the detection accuracy of a sensor.

[0047] Therefore, refer to Figure 2 In another embodiment, the cross-sectional structure of the temperature-resistant measuring rod 122 is the same as the cross-sectional structure of the first clearance hole 261.

[0048] It should be noted that existing sensors mostly employ a cylindrical measuring rod and magnetic core in a transmission structure. Because the circular rod lacks an anti-rotation limiting mechanism, it is prone to rotation during transportation, assembly, or use, causing a change in the position of the magnetic core relative to the coil and resulting in an initial zero-point offset. Simultaneously, the temperature-resistant measuring rod 122 is rigidly connected to the internal magnetic core 123; rotation will cause the magnetic core 123 to radially deflect within the coil, causing the air gap between the magnetic core 123 and the inner wall of the coil to change from uniform and symmetrical to one side being larger and the other smaller, thus altering the resolution. Therefore, the cross-sectional structure of the temperature-resistant measuring rod 122 in this application is identical to the cross-sectional structure of the first clearance hole 261, ensuring that the temperature-resistant measuring rod 122 will not rotate during transportation, assembly, or use, thereby guaranteeing normal sensor resolution and preventing zero-point offset.

[0049] See Figure 2 In another embodiment, the magnetic core 123 is a solid structure.

[0050] It should be noted that current sensors typically use hollow magnetic cores, which have a smaller effective magnetic cross-sectional area for the same geometric dimensions compared to solid magnetic cores. This limits their impact on coil inductance, further weakening the rate of inductance change per unit displacement, resulting in lower sensor resolution per unit distance and poor performance in short-stroke measurements. Therefore, the solid magnetic core structure used in this application can significantly improve the sensitivity of inductance to minute displacements, achieving high-precision resolution.

[0051] See Figure 2 In another embodiment, the frameless coil 124 has a circular cross-sectional structure.

[0052] It should be noted that traditional designs often wind inductors into an elliptical cross-section and use adjustable metal inserts to adjust the inductance value. This is based on the LC oscillation principle of inductance and the operating characteristics of displacement sensors. However, under the same volume constraint, the elliptical coil directly reduces the sensor's unit resolution, especially in small displacement detection applications. Therefore, the frameless coil 124 in this application adopts a circular cross-section structure. When energized, the magnetic field lines of the circular cross-section coil exhibit perfect axial symmetry, with consistent magnetic field strength at any radius within the coil, attenuating only uniformly along the radial direction. The magnetic field leakage at the coil edge is distributed in a ring-shaped symmetrical pattern. This uniformity means that when the magnetic core or the object being measured moves within the coil, the change in magnetic reluctance is continuous and linear, without any local magnetic field abrupt changes. Furthermore, the circular cross-section structure eliminates the need for an elliptical coil design, improving the sensor's original resolution under the same conditions without increasing the number of winding turns.

[0053] It should also be noted that, compared to framed coils, the frameless coil 124 does not require a certain amount of radial and axial space, which better meets the requirements of miniaturization design. Meanwhile, the frame is made of a non-magnetic material with a permeability close to that of air, effectively adding a fixed air gap between the coil and the core, increasing the total magnetic reluctance of the magnetic circuit. Simultaneously, the presence of the frame hinders the concentration of the magnetic field towards the core 123, causing some magnetic field leakage into the frame and reducing the coupling efficiency between the core and the coil. Furthermore, since the frame is mostly made of insulating material with low thermal conductivity, it is equivalent to wrapping the coil with a heat insulation layer, preventing rapid heat dissipation and causing the coil temperature to rise continuously, increasing the wire resistance.

[0054] In summary, by making the magnetic core 123 a solid structure, setting the cross-sectional structure of the temperature-resistant measuring rod 122 to be the same as the cross-sectional structure of the first clearance hole 261, and setting the frameless coil 124 to a circular cross-sectional structure, the resolution of the sensor can be improved, allowing the sensor to capture smaller changes in physical quantities, thereby improving detection accuracy.

[0055] See Figure 2 and Figure 4In another embodiment, the acquisition component 100 further includes an adjusting screw 130, which is disposed in the second clearance hole 262 and is located on one side of the frameless coil 124.

[0056] It should be noted that this application has an adjustment screw 130 next to the frameless coil 124. By rotating the adjustment screw 130, the insertion ratio with the inductor coil is changed, thereby fine-tuning the output ratio of the inductance.

[0057] The solutions of this application have been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of each embodiment have different focuses; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. Those skilled in the art should also understand that the actions and modules involved in the specification are not necessarily essential to this application. Furthermore, it is understood that the steps in the method of this application embodiment can be adjusted, combined, and deleted according to actual needs, and the modules in the device of this application embodiment can be combined, divided, and deleted according to actual needs. The various embodiments of this application have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or improvements to the technology in the market of the various embodiments, or to enable other those skilled in the art to understand the various embodiments disclosed herein.

Claims

1. An inductive contact displacement sensor, characterized in that, include: Data acquisition components; A housing assembly, including a housing, wherein the acquisition component is disposed on the housing; A heat-resistant component is provided, wherein a through hole is provided on the housing, and the heat-resistant component is embedded in the through hole.

2. The inductive contact displacement sensor according to claim 1, characterized in that, The temperature-resistant component includes a disc and a plug-in block. The disc is disposed on the plug-in block. After the plug-in block is embedded in the through hole, the disc fits into the housing.

3. The inductive contact displacement sensor according to claim 2, characterized in that, The plug block is provided with an anti-rotation groove.

4. The inductive contact displacement sensor according to claim 1, characterized in that, The housing assembly also includes a cover disposed on the housing.

5. The inductive contact displacement sensor according to claim 2, characterized in that, The housing assembly also includes a frustum disposed within the through hole.

6. The inductive contact displacement sensor according to claim 5, characterized in that, The housing assembly also includes screws, which are disposed in the through hole and pass through the plug block and the disc in sequence, and then abut against the frustum.

7. The inductive contact displacement sensor according to claim 1, characterized in that, The housing assembly further includes a fixing block, which is disposed on the housing and has a first clearance hole and a second clearance hole.

8. The inductive contact displacement sensor according to claim 7, characterized in that, The acquisition component includes a circuit board and a trigger, which are respectively disposed within the housing. The trigger is located on one side of the circuit board and includes a temperature-resistant measuring rod, a magnetic core, a frameless coil, and a spring. The housing assembly also includes a snap-fit ​​post with a clearance hole that communicates with a first clearance hole. The temperature-resistant measuring rod is partially exposed outside the first clearance hole. The first end of the magnetic core is connected to the temperature-resistant measuring rod, and the second end of the magnetic core passes through the first clearance hole and the clearance hole in sequence. The frameless coil is disposed on the snap-fit ​​post, and the spring is disposed within the clearance hole. The second end of the magnetic core is connected to the spring, which is located on the circuit board.

9. The inductive contact displacement sensor according to claim 8, characterized in that, The trigger includes a wire harness disposed on the circuit board, and the extension direction of the wire harness intersects with or is parallel to the length direction of the cover.

10. The inductive contact displacement sensor according to claim 9, characterized in that, The housing assembly further includes a cable outlet block, which is disposed on the housing, and the cable harness is disposed on the cable outlet block.

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