An immersed sensor with symmetrical anti-overload structure

Abstract

The application relates to the technical field of sensors, in particular to an immersed sensor with a symmetrical anti-overload structure, which comprises a pressure-bearing shell, the pressure-bearing shell is formed by two left and right halves to enclose a containing cavity, and the whole is a left-right symmetrical structure; a sensing sensitive element is arranged in the middle of the containing cavity and is left-right symmetrical about the central axis of the pressure-bearing shell, and a gap is left between the sensing sensitive element and the inner wall of the pressure-bearing shell; two medium isolation diaphragms are symmetrically arranged on the left and right end faces of the pressure-bearing shell; a buffer diaphragm for buffering overload is arranged between the two halves and wraps around the periphery of the sensing sensitive element, and the buffer diaphragm and the sensing sensitive element jointly divide the containing cavity into two left-right symmetrical parts; the containing cavity is filled with filling liquid, and the sensing sensitive element is immersed in the filling liquid. Through the cooperation of the symmetrical structure and the buffer diaphragm, unilateral overload impact is converted into global uniform pressure, instantaneous dynamic expansion is realized to eliminate stress concentration, and the sensor has high measurement accuracy and excellent anti-overload performance.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, specifically to an immersion sensor with a symmetrical overload-resistant structure. Background Technology

[0002] Immersion pressure and differential pressure sensors are widely used in industrial process control in petroleum, chemical, power, and metallurgical industries. Their working principle involves a diaphragm that isolates the pressure of the measured medium, transmitting it to an internal filling fluid (usually silicone oil). The filling fluid then transmits the pressure to the sensing element, which converts the pressure signal into an electrical signal for output. However, existing immersion pressure and differential pressure sensors generally employ an asymmetric housing structure without a buffer protection structure, exhibiting significant drawbacks.

[0003] The shell is subjected to asymmetrical forces on the left and right sides. When subjected to medium impact or instantaneous overload on one side, the diaphragm is subjected to concentrated stress, which can easily lead to plastic deformation and breakage, directly damaging the internal sensing elements. The diaphragm has no buffer pressure relief space, so the overload pressure cannot be buffered and released, resulting in poor overload resistance and a high probability of failure under impact conditions. The asymmetrical structure causes uneven stress distribution during temperature cycling and vibration tests, and fatigue cracks are prone to appear at the shell joints and lead wire welds.

[0004] Conventional industry optimization methods only involve thickening the isolation diaphragm, but this significantly reduces sensing sensitivity, making it impossible to simultaneously achieve both measurement accuracy and overload resistance, resulting in an irreconcilable technical contradiction. Therefore, we propose an immersion sensor with a symmetrical overload resistance structure. Summary of the Invention

[0005] The purpose of this invention is to provide an immersion sensor with a symmetrical overload-resistant structure to solve the problems mentioned in the background art. While ensuring high sensitivity, it significantly improves the sensor's shock resistance, pressure resistance, and long-term structural reliability, meeting the requirements for long-term stable operation under complex and harsh working conditions.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An immersion sensor with a symmetrical overload-resistant structure includes: The pressure-bearing shell has a symmetrical structure, consisting of two halves that enclose a cavity. A sensing element is disposed in the middle of the accommodating cavity, and the sensing element is symmetrical about the central axis of the pressure-bearing shell. A gap is left between the sensing element and the inner wall of the pressure-bearing shell. Two media-isolating diaphragms are symmetrically arranged on the left and right end faces of the pressure-bearing outer shell; A buffer diaphragm for buffering overload is placed between the two halves of the pressure-bearing shell and wraps around the periphery of the sensing element. The buffer diaphragm and the sensing element together divide the accommodating cavity into two symmetrical parts. The cavity is filled with a filling fluid, the sensing element is immersed in the filling fluid, and the gap between the sensing element and the inner wall of the pressure-bearing shell is filled with the filling fluid.

[0007] Preferably, the sensing element is cylindrical and has two circular end faces along its axial direction, with the outer peripheral surface of the sensing element located between the two circular end faces.

[0008] Preferably, the buffer diaphragm has a ring structure, with the outer edge of the buffer diaphragm welded to the outer edge of the pressure-bearing shell, and the inner edge of the buffer diaphragm welded to the outer peripheral surface of the sensing element. The buffer diaphragm and the sensing element together divide the accommodating cavity into a high-pressure side and a low-pressure side that are symmetrical and do not communicate with each other.

[0009] Preferably, the buffer diaphragm is a metal diaphragm with elastic properties. When subjected to overload impact, the metal diaphragm undergoes elastic flexural deformation, thereby changing the volume of the high-pressure side and the low-pressure side within the accommodating cavity by altering its own shape.

[0010] Preferably, the sensing element includes two bases symmetrically arranged on the left and right, with ports on the two bases. The ports of the two bases are welded together facing each other. An insulating substrate is provided on the inner side of each base. The sensing element also includes a common electrode plate and two fixed electrode plates. The common electrode plate with a disc-shaped flat plate structure is provided between the ports of the two bases. An arc-shaped curved surface structure of the fixed electrode plate is provided on each side of the two insulating substrates. The two fixed electrode plates are symmetrically arranged on the left and right sides of the common electrode plate and protrude from the side away from the common electrode plate. The fixed electrode plate on one side and the common electrode plate form a high-pressure cavity, and the fixed electrode plate on the other side and the common electrode plate form a low-pressure cavity.

[0011] Preferably, the inner edge of the buffer diaphragm is fixedly welded to the outer peripheral surface of one of the bases of the sensing element.

[0012] Preferably, a ceramic core is respectively disposed perpendicular to the central axis of the pressure-bearing shell on the base and the insulating substrate on both sides. Each ceramic core is connected to a fixed electrode plate on the same side. A through hole is opened inside the ceramic core. A through hole is opened on the fixed electrode plate. A liquid guiding channel is symmetrically opened through the two halves of the pressure-bearing shell. One end of the through hole of the ceramic core is connected to the through hole opened on the fixed electrode plate on the same side, and the other end is connected to the liquid guiding channel on the same side. The other end of the liquid guiding channel is connected to the inner side of the medium isolation membrane on the same side.

[0013] Preferably, the top of the pressure-bearing shell is symmetrically provided with two mounting channels, which are respectively connected to the connecting channel in the base on the same side. Each of the two connecting channels is provided with a conductive tube. One end of each conductive tube passes through the insulating substrate on the same side and is connected to the fixed electrode plate on that side. The other end of each conductive tube is connected to a copper wire, and the other end of the copper wire passes through the mounting channel and is connected to an external wire.

[0014] Preferably, the copper wire is wrapped with a sheath, an insulator is welded to the top of the mounting channel, and one end of the copper wire passes through the insulator and is connected to an external conductor.

[0015] Preferably, the bottom of the pressure-bearing shell has two symmetrical filling channels, which are respectively connected to the high-pressure side and the low-pressure side of the accommodating cavity for vacuum filling of filling liquid. The filling channels are sealed after filling is completed.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The immersion sensor with a symmetrical overload resistance structure forms a two-stage buffer structure by setting a buffer diaphragm around the sensing element and isolating it with an outer medium diaphragm. When an overload impact occurs, the buffer diaphragm absorbs the impact energy through elastic deformation, effectively preventing the sensing element from bearing overload stress and significantly improving the overload resistance. The instantaneous impact will not cause plastic deformation of the isolation diaphragm or the sensing element.

[0017] 2. This immersion sensor with a symmetrical overload-resistant structure is designed with a pressure-bearing shell that is symmetrically arranged on the left and right sides, and the high-pressure side and the low-pressure side that are symmetrically arranged on the left and right sides. The overload stress is evenly distributed, eliminating stress concentration on one side. The elastic deformation of the buffer diaphragm is completely reversible, with no permanent measurement offset, ensuring the stability of the zero point of the differential pressure measurement and reliable accuracy. It combines measurement accuracy with overload resistance.

[0018] 3. This immersion sensor with a symmetrical overload-resistant structure completely immerses the sensing element in the filling liquid. Utilizing the incompressible and isotropic pressure transmission characteristics of the filling liquid, the static pressure is uniformly transmitted to the sensing element in all directions. This solves the problem of static pressure influence error under high static pressure conditions and improves the output stability and measurement reliability of the sensor under high static pressure conditions. Attached Figure Description

[0019] Figure 1 This is a longitudinal sectional view of the overall structure of an immersion sensor according to an embodiment of the present invention; Figure 2 for Figure 1 Enlarged view of the structure at point A in the middle; Figure 3 for Figure 1 Enlarged view of the structure at point B; Figure 4 This is a longitudinal sectional view of the overall structure of an immersion sensor according to an embodiment of the present invention, omitting the sensing element; Figure 5 This is a cross-sectional view of the overall structure of an immersion sensor according to an embodiment of the present invention.

[0020] In the diagram: 1. Pressure-bearing outer shell; 10. Half body; 11. Filling channel; 12. Liquid guiding channel; 2. Receptacle; 20. Gap; 21. High-pressure side; 22. Low-pressure side; 3. Sensing element; 31. Base; 311. Connection channel; 32. Common electrode plate; 33. Insulating substrate; 34. Fixed electrode plate; 35. Ceramic core; 36. High-pressure chamber; 37. Low-pressure chamber; 4. Dielectric isolation diaphragm; 5. Buffer diaphragm; 6. Installation channel; 61. Copper wire; 62. Conductive tube; 63. Sheath; 64. Insulator. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0025] Please see Figures 1-5 As shown, the present invention provides a technical solution: An immersion sensor with a symmetrical overload-resistant structure includes: The pressure-bearing outer shell 1 includes two halves 10, left and right. The pressure-bearing outer shell 1 has a symmetrical structure and is made of rigid metal materials such as stainless steel 316. Its interior is enclosed to form a receiving cavity 2. The sensing element 3 is disposed in the middle of the accommodating cavity 2, and the sensing element 3 is symmetrical about the central axis ZZ of the pressure-bearing shell 1. A gap 20 is left between the sensing element 3 and the inner wall of the pressure-bearing shell 1. Two media isolation diaphragms 4 are symmetrically arranged on the left and right end faces of the pressure-bearing outer shell 1 to transmit the pressure of the external measured medium to the interior of the accommodating cavity 2. The media isolation diaphragms 4 are mature existing technology, made of 316L stainless steel, with a corrugated structure. They are in direct contact with the measured medium and are the first pressure transmission barrier. The buffer diaphragm 5, used to buffer overload, is disposed between the two halves 10 of the pressure-bearing housing 1 and wraps around the periphery of the sensing element 3. The buffer diaphragm 5 and the sensing element 3 together divide the accommodating cavity 2 into two symmetrical parts. The cavity 2 is filled with filling fluid, the sensing element 3 is immersed in the filling fluid, and the gap 20 between the sensing element 3 and the inner wall of the pressure-bearing shell 1 is filled with filling fluid.

[0026] To clearly describe the structural layout and symmetry of this invention, a spatial rectangular coordinate system is defined as follows: the direction connecting the two halves 10 in the horizontal plane is the XX direction (left-right direction); the direction perpendicular to XX in the horizontal plane is the YY direction (front-back direction); and the vertical direction is the ZZ direction (up-down direction). In the appendix... Figure 1 In this diagram, the ZZ direction is the central axis of the pressure-bearing outer shell 1, and the pressure-bearing outer shell 1 is arranged symmetrically about the ZZ axis. The origin of the coordinate system is located at the geometric center of the pressure-bearing outer shell 1, that is, at the intersection of the symmetrical center planes in the XX and YY directions and the symmetrical central axis in the ZZ direction. Based on this origin, the sensing element 3, the buffer diaphragm 5, and the accommodating cavity 2 are all arranged symmetrically about the ZZ axis. See also the appendix. Figure 5The pressure-bearing outer shell 1 and the accommodating cavity 2 are also symmetrical about the YY axis, thus ensuring that the sensor has a symmetrical geometric configuration and pressure transmission path on both the left and right sides.

[0027] It is worth noting that the filling fluid is a liquid medium with good incompressibility and good uniform pressure transmission characteristics in all directions. In some embodiments, the filling fluid is silicone oil, the cavity 2 is a silicone oil cavity, the sensing element 3 is completely immersed in the filling fluid, and the gap between the sensing element 3 and the inner wall of the pressure-bearing shell 1 is also completely filled with the filling fluid, so as to achieve full immersion static pressure balance.

[0028] In this invention, the sensing element 3 is cylindrical and has two circular end faces along its axial direction XX, with the outer peripheral surface of the sensing element 3 located between the two circular end faces.

[0029] Furthermore, the buffer diaphragm 5 has a ring-shaped structure. The outer edge of the buffer diaphragm 5 is welded to the outer edge of the pressure-bearing shell 1, and the inner edge of the buffer diaphragm 5 is welded to the outer peripheral surface of the sensing element 3. The buffer diaphragm 5 and the sensing element 3 together divide the accommodating cavity 2 into a high-pressure side 21 and a low-pressure side 22 that are symmetrical and not interconnected. For ease of explanation of the working principle of this technical solution, the left side of the accommodating cavity 2 is defined as the high-pressure side 21, and the right side as the low-pressure side 22.

[0030] It is worth noting that in the existing sensor structure, in order to prevent the sensing element 3 from shaking in the accommodating cavity 2, it is necessary to fix it to the inner wall of the pressure-bearing shell 1. The existing technology usually uses a welding lip between the sensing element 3 and the inner wall of the pressure-bearing shell 1 for welding and fixing. However, in this embodiment, by welding the inner edge of the buffer diaphragm 5 to the outer peripheral surface of the sensing element 3, the buffer diaphragm 5 also plays the role of fixing the sensing element 3. Therefore, it is no longer necessary to use other methods to further fix the sensing element 3.

[0031] This design further ensures the left-right symmetry of the immersion sensor with a symmetrical overload-resistant structure in this invention, guaranteeing the structural symmetry of the high-pressure side 21 and low-pressure side 22 of the accommodating cavity 2. This also ensures the consistency of the pressure transmission paths on both sides. As long as the external pressure on both sides is equal, the pressure in the oil chambers on both sides will be completely equal, ensuring no additional bias at the zero point. In traditional asymmetrical structures, after overload, the diaphragm on one side may undergo permanent deformation or residual stress, causing the pressure transmission characteristics on both sides to become asymmetrical. Even after returning to normal pressure, the zero point will drift.

[0032] Furthermore, the buffer diaphragm 5 is a metal diaphragm with elastic properties. Under overload impact, the metal diaphragm undergoes elastic flexural deformation, changing its shape to alter the volume of the high-pressure side 21 and the low-pressure side 22 within the accommodating cavity 2. Its working principle is further explained below: During normal differential pressure measurement, the pressure on the left and right sides pushes the medium isolation diaphragm 4, which transmits the pressure to both sides of the sensing element 3 through the filling liquid in the liquid channel 12. Since the cavity volumes of the high-pressure side 21 and the low-pressure side 22 are the same and the pressure transmission path lengths are completely symmetrical, it ensures that there is no additional bias at the zero point and the measurement accuracy is high.

[0033] When a unilateral (assuming high-pressure side 21) instantaneous overpressure impact occurs, the corrugated area of ​​the buffer diaphragm 5 is compressed by the high-pressure oil on the high-pressure side 21, causing elastic flexural deformation towards the low-pressure side 22, expanding the volume of the silicone oil cavity on the high-pressure side 21 to absorb the impact peak. Simultaneously, as the buffer diaphragm 5 expands towards the low-pressure side 22, it compresses the oil cavity on the low-pressure side 22, effectively establishing a dynamic reaction force or back pressure on the low-pressure side 22. This back pressure counteracts most of the unidirectional thrust on the high-pressure side, thus preventing the pressure-sensing diaphragm of the sensing element 3 (i.e., the attached...) from... Figure 1 , 5 The shared electrode 32 and the fixed electrode 34 in the middle are deflected or crushed by unilateral pressure. In other words, the completely symmetrical shell evenly distributes the overload stress on the high and low pressure sides, avoiding stress concentration on one side. This deformation realizes the instantaneous expansion of the buffer cavity volume around the sensing element 3, thereby converting the peak impact energy into the elastic potential energy of the buffer diaphragm 5, and significantly reducing the pressure measuring diaphragm (attached) transmitted to the inside of the sensing element 3. Figure 1 , 5 The mechanical stress of the common electrode 32 and the fixed electrode 34 in the pressure measuring diaphragm (attached) affects the pressure measuring diaphragm. Figure 1 , 5 The common electrode plate 32 and the fixed electrode plate 34 are protected to extend their service life.

[0034] After the overload pressure disappears, the buffer diaphragm 5 rebounds synchronously to its initial position using the elastic restoring force of the metal itself, and the volume of the buffer cavity is restored. Because the deformation is strictly symmetrical and completely within the elastic limit of the material, there is no plastic deformation or residual stress, thus ensuring that the zero point will not have a permanent measurement offset after overload.

[0035] When instantaneous overpressure impacts occur simultaneously on both sides, the symmetrical anti-overload structure of this invention achieves synergistic buffering through the elastic deformation of the buffer diaphragm 5 and the uniform pressure characteristics of the filling fluid. If the pressure amplitudes on both sides are unequal, the buffer diaphragm 5 undergoes elastic flexural deformation towards the opposite side under the push of the high-pressure filling fluid on the high-pressure side, instantaneously expanding the volume of the high-pressure side of the accommodating cavity 2 to absorb the impact peak. At the same time, the low-pressure side provides reverse support force under the back pressure. The buffer diaphragm 5 generates deformation matching the real-time pressure difference, converting the unidirectional impact energy into diaphragm elastic potential energy and distributing it to the symmetrical cavity, avoiding stress concentration on the sensing element 3. If the pressure amplitudes on both sides are equal or similar, the buffer diaphragm 5 is subjected to thrusts of equal magnitude and opposite direction. The diaphragm hardly produces net deformation. After the impact energy is uniformly transmitted in all directions by the filling fluid, it is evenly distributed by the symmetrical rigid structure of the pressure-bearing shell 1. The sensing element 3 is in a state of full immersion static pressure equilibrium, and its pressure measuring diaphragm (attached) Figure 1 , 5 The shared electrode 32 and the fixed electrode 34 are not subjected to additional stress. After the overload disappears, the buffer diaphragm 5 rebounds synchronously to its initial symmetrical position due to the elasticity of the metal itself. The deformation throughout the process is within the elastic limit of the material, with no plastic deformation or residual stress, ensuring the long-term stability of the zero point and range. Therefore, regardless of the overload pressure relationship on both sides, this invention can achieve efficient absorption and balanced release of impact energy through the differentiated deformation response of the symmetrical buffer diaphragm 5 and the incompressible pressure transmission characteristics of the filling fluid, effectively protecting the pressure measuring diaphragm of the sensing element 3 (attached). Figure 1 , 5 The common electrode 32 and the fixed electrode 34 are protected from damage.

[0036] If it is a traditional single-sided opening and asymmetrical structure, when one side is overloaded, the pressure is directly pressed on the back or weak side of the sensing element 3. There is no symmetrical cavity to disperse this force, which causes the pressure measuring diaphragm of the sensing element 3 to bend in one direction, causing brittle fracture or permanent bending deformation (complete zero-point offset). This is precisely the advantage of this technical solution compared with the traditional design.

[0037] It is worth noting that the industry's conventional optimization method for dealing with overload impacts—thickening the dielectric diaphragm 4—has a significant drawback: while thickening increases the diaphragm's stiffness, it does not increase the material's yield strength by the same margin. Increased stiffness means that the diaphragm's elastic deformation space is compressed under load. When a sudden transient overload impact occurs, the thickened and "hardened" diaphragm cannot effectively absorb and disperse the impact energy through its own significant elastic bending, causing the impact load to concentrate locally on the diaphragm, forming stress concentrations far exceeding the average stress. When this local stress peak exceeds the material's yield limit, the diaphragm undergoes irreversible plastic deformation. This plastic deformation permanently alters the diaphragm's geometric curvature and oil cavity volume, and introduces residual stress inside the diaphragm. This means that even if the external pressure is completely unloaded, the sensor's internal hydraulic balance cannot be restored, resulting in permanent zero-point drift and measurement offset, severely affecting the sensor's long-term stability and repeatability. This technical solution utilizes a thin and elastic buffer diaphragm 5 to absorb and buffer impact energy through controllable elastic deformation, ensuring that the buffer diaphragm 5 always operates within its elastic range. After the overload disappears, the buffer diaphragm 5 can perfectly rebound, thereby ensuring the long-term stability of measurement accuracy and achieving the goal of simultaneously ensuring measurement accuracy and overload resistance.

[0038] In this embodiment, the sensing element 3 includes two bases 31 symmetrically arranged on the left and right sides. The bases 31 are made of metal material, preferably stainless steel. The two bases 31 have ports, which are welded together facing each other. An insulating substrate 33 is provided on the inner side of the bases 31. The sensing element 3 also includes a common electrode plate 32 and two fixed electrode plates 34. The fixed electrode plates 34 and the common electrode plate 32 constitute the aforementioned pressure measuring diaphragm and perform the function of measuring pressure. The material and structure of the pressure measuring diaphragm are existing technologies and will not be described in detail here. A common electrode plate 32 with a disc-shaped flat plate structure is disposed between the ports of the two bases 31. A fixed electrode plate 34 with an arc-shaped curved surface structure is disposed on each side of the two insulating substrates 33. The two fixed electrode plates 34 are symmetrically arranged on the left and right sides of the common electrode plate 32, and protrude away from the common electrode plate 32 respectively. The fixed electrode plate 34 on one side and the common electrode plate 32 form a high-pressure cavity 36, and the fixed electrode plate 34 on the other side and the common electrode plate 32 form a low-pressure cavity 37. For ease of explanation of the working principle of this technical solution, it is specified that the fixed electrode plate 34 on the left side and the common electrode plate 32 form the high-pressure cavity 36, and the fixed electrode plate 34 on the right side and the common electrode plate 32 form the low-pressure cavity 37.

[0039] It is understandable that the inner edge of the buffer diaphragm 5 is fixedly welded to the outer peripheral surface of one of the bases 31 of the sensing element 3, thereby dividing the accommodating cavity 2 into a high-pressure side 21 and a low-pressure side 22 that are symmetrical and not connected to each other through the cooperation of the buffer diaphragm 5 and the sensing element 3. Moreover, the sensing element 3 can be further fixed through the buffer diaphragm 5.

[0040] Furthermore, a ceramic core 35 is respectively installed on the base 31 and the insulating substrate 33 on both sides, perpendicular to the central axis ZZ of the pressure-bearing shell 1. Each ceramic core 35 is connected to the fixed electrode plate 34 on the same side. A through hole 351 is opened through the inside of the ceramic core 35. A through hole 341 is opened in the fixed electrode plate 34. A liquid guiding channel 12 is symmetrically opened through the two halves 10 of the pressure-bearing shell 1. One end of the through hole 351 of the ceramic core 35 is connected to the through hole 341 opened in the fixed electrode plate 34 on the same side, and the other end is connected to the liquid guiding channel 12 on the same side. The other end of the liquid guiding channel 12 is connected to the inner side of the medium isolation diaphragm 4 on the same side.

[0041] It is worth noting that the two bases 31 are symmetrically arranged on the left and right sides, serving as the supporting skeleton for the sensing element 3. Their ports are arranged facing each other and, together with the common electrode plate 32 and the fixed electrode plate 34, form a high-pressure chamber 36 and a low-pressure chamber 37. The ceramic core 35, which is disposed through the base 31 and the insulating substrate 33, provides a pressure transmission channel from the dielectric isolation diaphragm 4 to the measuring cavity. The connection channel 311 inside the base 31 is used to accommodate the conductive tube 62 to lead out the capacitance signal. At the same time, the outer side of the base 31 provides a welding and fixing position for the buffer diaphragm 5, thereby realizing the overall support for the sensing element 3. It is understandable that the high-pressure chamber 36 is connected to the medium isolation diaphragm 4 of the high-pressure side 21 through the through hole 341 of the fixed electrode plate 34 of the high-pressure side 21, the through hole 351 of the ceramic core 35, and the liquid guiding channel 12 of the high-pressure side 21. The low-pressure chamber 37 is connected to the medium isolation diaphragm 4 of the low-pressure side 22 through the through hole 341 of the fixed electrode plate 34 of the low-pressure side 22, the through hole 351 of the ceramic core 35, and the liquid guiding channel 12 of the low-pressure side 22. The pressure passes through the medium isolation diaphragm 4, the liquid guiding channel 12, the through hole 351 of the ceramic core 35, and the through hole 341 of the fixed electrode 34, and finally acts on the measuring oil chamber formed by the fixed electrode 34 and the common electrode 32. That is to say, the pressure on the high-pressure side 21 passes through the medium isolation diaphragm 4, the liquid guiding channel 12, the through hole 351 of the ceramic core 35, and the through hole 341 of the fixed electrode 34, and finally acts on the high-pressure chamber 36 formed by the fixed electrode 34 and the common electrode 32 on the high-pressure side 21. The pressure on the low-pressure side 22 passes through the medium isolation diaphragm 4, the liquid guiding channel 12, the through hole 351 of the ceramic core 35, and the through hole 341 of the fixed electrode 34, and finally acts on the low-pressure chamber 37 formed by the fixed electrode 34 and the common electrode 32 on the low-pressure side 22.

[0042] In this invention, two mounting channels 6 are symmetrically arranged through the top of the pressure-bearing shell 1. The two mounting channels 6 are respectively connected to the connecting channel 311 in the base 31 on the same side. A conductive tube 62 is respectively arranged inside the two connecting channels 311. One end of each conductive tube 62 passes through the insulating substrate 33 on the same side and is connected to the fixed electrode plate 34 on that side. The other end of each conductive tube 62 is connected to a copper wire 61. The other end of the copper wire 61 passes through the mounting channel 6 and is connected to an external wire.

[0043] Furthermore, the copper wire 61 is wrapped with a sheath 63, and an insulator 64 is welded to the top of the installation channel 6 to prevent moisture from entering. One end of the copper wire 61 passes through the insulator 64 and is connected to an external conductor.

[0044] Understandably, in the signal transmission path, the fixed electrode plates 34 on both sides form differential pressure detection capacitors with the common electrode plate 32, and the capacitance change signal on the fixed electrode plate 34 is led out through the conductive tube 62 connected to it. The conductive tube 62 on each side is set in the connection channel 311 in the base 31 on the same side. One end of the conductive tube 62 passes through the insulating substrate 33 and is electrically connected to the fixed electrode plate 34 on that side, and the other end is connected to the copper wire 61. The copper wire 61 extends upward along the mounting channel 6 and passes through the insulator 64 sealed at the top of the mounting channel 6 before connecting to the external wire to transmit the capacitance change signal on the fixed electrode plate 34 to the external processing circuit. The copper wire 61 is covered with a sheath 63 to keep it insulated from the pressure-bearing outer shell 1; the insulator 64 also serves as a seal to prevent external moisture from entering the cavity 2 along the mounting channel 6, ensuring the insulation reliability and stability of the sensor during long-term operation.

[0045] In this invention, two symmetrical filling channels 11 are formed at the bottom of the pressure-bearing outer shell 1. These two channels 11 are respectively connected to the high-pressure side 21 and the low-pressure side 22 of the accommodating cavity 2 for vacuum filling with filling fluid. The filling channels 11 are sealed after filling. In a preferred embodiment, under vacuum conditions, degassed silicone oil is injected into the high-pressure side 21 and the low-pressure side 22 of the accommodating cavity 2 through the two filling channels 11. The vacuum environment ensures that no air bubbles remain in the filling fluid, guaranteeing the rigidity of the pressure transmission. After filling, the filling channels 11 are permanently sealed using a metal plug and annular laser welding to ensure no leakage during long-term use.

[0046] In summary, the symmetrical overload-resistant structure of the immersion sensor provided by the present invention, through the left and right symmetry of the pressure-bearing shell 1, the surrounding wrapping of the buffer diaphragm 5, and the fully immersed filling liquid layout of the sensing element 3, constructs an integrated structural system with dual protection capabilities of "overload resistance" and "static pressure resistance". Its core mechanism is as follows: During normal measurement, the completely symmetrical pressure transmission path ensures that there is no additional bias at the zero point of the pressure difference, and the measurement accuracy is not affected by the structural asymmetry; when there is an overload impact on one side (assuming it is the high-pressure side 21), the buffer diaphragm 5 undergoes elastic flexural deformation, absorbs the impact peak through instantaneous expansion, and establishes dynamic back pressure on the low-pressure side 22 to offset the unidirectional thrust, thereby effectively protecting the pressure measuring diaphragm of the sensing element 3 from plastic deformation or brittle fracture. After the overload disappears, the buffer diaphragm 5 rebounds synchronously due to the elasticity of the metal itself, with no residual stress or permanent deformation, ensuring the long-term stability of the zero point and range; when instantaneous overpressure impacts occur on both sides at the same time, the symmetrical anti-overload structure of the present invention achieves synergistic buffering through the elastic deformation of the buffer diaphragm 5 and the global pressure equalization characteristics of the filling fluid. If the pressure amplitudes on both sides are unequal, the buffer diaphragm 5 deforms in accordance with the real-time pressure difference, converting the unidirectional impact energy into the diaphragm's elastic potential energy and distributing it to the symmetrical cavity, thus avoiding stress concentration on the sensing element 3. After the overload disappears, the buffer diaphragm 5 rebounds synchronously due to the elasticity of the metal itself. If the pressure amplitudes on both sides are equal or similar, the buffer diaphragm 5 is subjected to thrusts of equal magnitude and opposite direction. The diaphragm hardly undergoes any net deformation. After the impact energy is uniformly transmitted in all directions by the filling fluid, it is evenly distributed by the symmetrical rigid structure of the pressure-bearing shell 1. The sensing element 3 is in a state of full immersion static pressure equilibrium, and its pressure measuring diaphragm (attached) Figure 1 , 5 The common electrode 32 and the fixed electrode 34 are not subjected to additional stress. At the same time, the sensing element 3 is completely immersed in the filling liquid. By utilizing the incompressibility of the liquid and the isotropic pressure transmission characteristics, the static pressure influence error and output nonlinearity caused by high static pressure are eliminated from the physical level.

[0047] Compared to traditional solutions in existing technologies that sacrifice sensitivity by simply thickening the isolation diaphragm or cause stress concentration by using an asymmetrical shell, this invention replaces rigid thickening with thin-walled elastic buffering, replaces unilateral pressure bearing with symmetrical pressure equalization, and replaces rigid contact force transmission with full immersion static pressure balance. At the same time, it takes into account high sensitivity, strong overload resistance, high static pressure stability, and long-term reliability at the structural level. It can be widely used in high-precision differential pressure measurement scenarios under complex and harsh working conditions such as petroleum, chemical, power, and metallurgy.

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An immersion sensor with a symmetrical overload-resistant structure, characterized in that, include: The pressure-bearing shell (1) has a symmetrical structure, including two halves (10) which enclose a cavity (2). The sensing element (3) is located in the middle of the accommodating cavity (2), and the sensing element (3) is symmetrical about the central axis (ZZ) of the pressure-bearing shell (1). A gap (20) is left between the sensing element (3) and the inner wall of the pressure-bearing shell (1). Two media isolation diaphragms (4) are symmetrically arranged on the left and right end faces of the pressure-bearing shell (1); A buffer diaphragm (5) for buffering overload is set between the two halves (10) of the pressure-bearing shell (1) and wrapped around the periphery of the sensing element (3). The buffer diaphragm (5) and the sensing element (3) together divide the accommodating cavity (2) into two symmetrical parts. The cavity (2) is filled with filling fluid, the sensing element (3) is immersed in the filling fluid, and the gap (20) between the sensing element (3) and the inner wall of the pressure-bearing shell (1) is filled with filling fluid.

2. The immersion sensor with a symmetrical overload-resistant structure according to claim 1, characterized in that, The sensing element (3) is cylindrical and has two circular end faces along its axial direction (XX), with the outer circumferential surface of the sensing element (3) between the two circular end faces.

3. The immersion sensor with a symmetrical overload-resistant structure according to claim 2, characterized in that, The buffer diaphragm (5) has a ring structure. The outer edge of the buffer diaphragm (5) is welded to the outer edge of the pressure-bearing shell (1), and the inner edge of the buffer diaphragm (5) is welded to the outer peripheral surface of the sensing element (3). The buffer diaphragm (5) and the sensing element (3) together divide the accommodating cavity (2) into a high-pressure side (21) and a low-pressure side (22) that are symmetrical and do not communicate with each other.

4. The immersion sensor with a symmetrical overload-resistant structure according to claim 1, characterized in that, The buffer diaphragm (5) is a metal diaphragm with elastic properties. When the metal diaphragm is subjected to overload impact, it undergoes elastic flexural deformation and changes its own shape to realize the change of the volume of the high-pressure side (21) and the low-pressure side (22) in the accommodating cavity (2).

5. The immersion sensor with a symmetrical overload-resistant structure according to claim 3, characterized in that, The sensing element (3) includes two bases (31) arranged symmetrically on the left and right sides. The two bases (31) are provided with ports. The ports of the two bases (31) are welded together facing each other. An insulating substrate (33) is provided on the inner side of the base (31). The sensing element (3) also includes a common electrode plate (32) and two fixed electrode plates (34). The common electrode plate (32) with a disc-shaped flat plate structure is provided between the ports of the two bases (31). The fixed electrode plate (34) with an arc-shaped curved surface structure is provided on the opposite side of the two insulating substrates (33). The two fixed electrode plates (34) are symmetrically arranged on the left and right sides of the common electrode plate (32) and protrude to the side away from the common electrode plate (32). The fixed electrode plate (34) on one side and the common electrode plate (32) form a high-pressure cavity (36). The fixed electrode plate (34) on the other side and the common electrode plate (32) form a low-pressure cavity (37).

6. The immersion sensor with a symmetrical overload-resistant structure according to claim 5, characterized in that, The inner edge of the buffer diaphragm (5) is fixedly welded to the outer peripheral surface of one of the bases (31) of the sensing element (3).

7. The immersion sensor with a symmetrical overload-resistant structure according to claim 5, characterized in that, A ceramic core (35) is respectively installed on the base (31) and the insulating substrate (33) on both sides, perpendicular to the central axis (ZZ) of the pressure-bearing shell (1). Each ceramic core (35) is connected to the fixed electrode plate (34) on the same side. A through hole (351) is opened through the inside of the ceramic core (35). A through hole (341) is opened on the fixed electrode plate (34). Two halves (10) of the pressure-bearing shell (1) are symmetrically provided with liquid guiding channels (12). One end of the through hole (351) of the ceramic core (35) is connected to the through hole (341) opened on the fixed electrode plate (34) on the same side, and the other end is connected to the liquid guiding channel (12) on the same side. The other end of the liquid guiding channel (12) is connected to the inner side of the medium isolation membrane (4) on the same side.

8. The immersion sensor with a symmetrical overload-resistant structure according to claim 5, characterized in that, The pressure-bearing shell (1) has two symmetrically arranged mounting channels (6) on its top. The two mounting channels (6) are respectively connected to the connecting channel (311) in the base (31) on the same side. Each of the two connecting channels (311) has a conductive tube (62) inside. One end of each conductive tube (62) passes through the insulating substrate (33) on the same side and is connected to the fixed electrode plate (34) on that side. The other end of each conductive tube (62) is connected to a copper wire (61). The other end of the copper wire (61) passes through the mounting channel (6) and is connected to an external wire.

9. The immersion sensor with a symmetrical overload-resistant structure according to claim 8, characterized in that, The copper wire (61) is wrapped with a sheath (63), and an insulator (64) is welded to the top of the installation channel (6). One end of the copper wire (61) passes through the insulator (64) and is connected to an external conductor.

10. The immersion sensor with a symmetrical overload-resistant structure according to claim 3, characterized in that, The pressure-bearing outer shell (1) has two symmetrical filling channels (11) at its bottom. The two filling channels (11) are respectively connected to the high-pressure side (21) and the low-pressure side (22) of the accommodating cavity (2) for vacuum filling of filling liquid. The filling channels (11) are sealed after filling.

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