Oil pipe sensing device

Abstract

The utility model provides an oil pipe sensing device which is applied to the technical field of detection and comprises an oil pipe, and liquid flows in the oil pipe. The spring base is arranged in the oil pipe and fixedly connected with the inner wall of the oil pipe, and at least one through hole is formed in the spring base; the first end of the spring is fixedly connected with the spring base; the permanent magnet is arranged in the oil pipe and fixedly connected to the second end of the spring, the permanent magnet moves in the axial direction of the oil pipe under liquid pressure to drive the spring to be compressed, and the cross sectional area of the permanent magnet is smaller than that of the oil pipe; the magnetic inductor is fixedly connected to the outer wall of the oil pipe, and the induction face of the magnetic inductor is tightly attached to the outer wall of the oil pipe. No sensor element is in direct contact with liquid, the service life of core components of the induction device is prolonged to a certain extent, and therefore the reliability of the induction device is enhanced.

Description

Technical Field

[0001] This application relates to the field of detection technology, and in particular to an oil pipe sensing device. Background Technology

[0002] When detecting the flow of corrosive liquids or the flow of corrosive fuels, traditional flow rate sensors need to be in direct contact with the liquid being measured. In corrosive media, electronic components are prone to corrosion and failure. Therefore, the reliability of traditional oil pipe sensing devices is relatively low. Utility Model Content

[0003] This application provides an oil pipe sensing device to solve the problem of low reliability of traditional oil pipe sensing devices.

[0004] To address the aforementioned technical problems, this application provides an oil pipe sensing device, comprising: an oil pipe, wherein liquid flows through the inside of the oil pipe;

[0005] A spring base is disposed inside the oil pipe and fixedly connected to the inner wall of the oil pipe. The spring base is provided with at least one through hole.

[0006] A spring, wherein the first end of the spring is fixedly connected to the spring base;

[0007] A permanent magnet is disposed inside the oil pipe and fixedly connected to the second end of the spring. The permanent magnet moves axially along the oil pipe under liquid pressure, causing the spring to compress. The cross-sectional area of ​​the permanent magnet is smaller than the cross-sectional area of ​​the oil pipe.

[0008] A magnetic sensor is fixedly connected to the outer wall of the oil pipe, and the sensing surface of the magnetic sensor is in close contact with the outer wall of the oil pipe.

[0009] One of the above technical solutions has the following advantages or beneficial effects:

[0010] In this embodiment, the device includes an oil pipe through which liquid flows; a spring base disposed inside the oil pipe and fixedly connected to its inner wall, the spring base having at least one through hole; a spring, the first end of which is fixedly connected to the spring base; a permanent magnet disposed inside the oil pipe and fixedly connected to the second end of the spring, the permanent magnet moving axially along the oil pipe under liquid pressure, causing the spring to compress, the cross-sectional area of ​​the permanent magnet being smaller than that of the oil pipe; and a magnetic sensor fixedly connected to the outer wall of the oil pipe, the sensing surface of the magnetic sensor being in close contact with the outer wall of the oil pipe. This embodiment linearly converts the flow velocity of the liquid in the oil pipe into spring compression, causing the permanent magnet to move axially within the oil pipe and trigger the magnetic field signal of an external magnetic sensor, achieving non-contact detection. This avoids direct contact between the sensor element and the liquid, extending the lifespan of the core components of the sensing device to some extent, thereby enhancing the reliability of the sensing device. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is one of the structural schematic diagrams of the oil pipe sensing device provided in the embodiments of this application;

[0013] Figure 2 This is a second schematic diagram of the structure of the oil pipe sensing device provided in one embodiment of this application;

[0014] Figure 3 This is a structural diagram of a spring base provided in an embodiment of this application;

[0015] Figure 4 This is a structural diagram of a spring provided in one embodiment of this application;

[0016] Figure 5 This is the third schematic diagram of the structure of the oil pipe sensing device provided in one embodiment of this application;

[0017] Figure 6 This is the fourth schematic diagram of the structure of the oil pipe sensing device provided in one embodiment of this application;

[0018] Figure 7 This is a structural diagram of a permanent magnet provided in one embodiment of this application;

[0019] Figure 8 This is a structural diagram of a magnetic sensor provided in one embodiment of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] like Figure 1 As shown, this embodiment of the utility model provides an oil pipe 1 sensing device, such as... Figure 1 As shown, it includes:

[0022] Oil pipe 1, the interior of which is supplied with liquid;

[0023] Spring base 2, which is disposed inside the oil pipe 1 and fixedly connected to the inner wall of the oil pipe 1, and the spring base 2 is provided with at least one through hole;

[0024] Spring 3, the first end of which is fixedly connected to spring base 2;

[0025] A permanent magnet 4 is disposed inside the oil pipe 1 and fixedly connected to the second end of the spring 3. The permanent magnet 4 moves axially along the oil pipe 1 under the pressure of the liquid, thereby compressing the spring 3. The cross-sectional area of ​​the permanent magnet 4 is smaller than that of the oil pipe 1.

[0026] A magnetic sensor 5 is fixedly connected to the outer wall of the oil pipe 1, and the sensing surface of the magnetic sensor 5 is in close contact with the outer wall of the oil pipe 1.

[0027] In this embodiment of the utility model, Figure 1 and Figure 2 The structural form is illustrated by the example above. The oil pipe 1 serves as a liquid flow channel and also provides mounting support for internal components. The shape and material of the oil pipe 1 are not specifically limited in this embodiment; exemplarily, stainless steel, Hastelloy, or a carbon fiber tube lined with polytetrafluoroethylene can all be used. The spring base 2 can be used to fix the spring 3 and support the permanent magnet 4 in the oil pipe 1, while also providing a liquid flow channel. The spring base 2 can be as follows... Figure 3As shown, other shapes can also be used. This application does not specifically limit the shape. Similarly, this application does not specifically limit the connection method of the spring base 2. It can be connected to the inner wall of the oil pipe 1 by automatic argon arc welding or by stainless steel bolts to the prefabricated flange of the inner wall of the oil pipe 1, and sealed with an O-ring. Other connection methods such as clamps and adhesives can also be used. The above-mentioned through hole design ensures liquid flow. This application does not limit the number, layout and shape of the through holes.

[0028] The aforementioned spring 3 can convert the axial displacement of the permanent magnet 4 into elastic force, achieving a linear mapping from flow velocity to displacement. The shape and material of the spring 3 are not specifically limited in this embodiment; reference can be made to... Figure 4 The spring 3 can be made of nickel-titanium shape memory alloy or stainless steel. The specific stiffness coefficient of the spring 3 can be set according to the specific working conditions. The embodiments of this application do not specifically limit the connection method of the spring 3. In some optional embodiments, the two ends of the spring 3 are hinged to the spring base 2 and the permanent magnet 4 through pins. The pins and the base holes can be clearance fit, which allows the permanent magnet 4 to swing within a certain angle range to compensate for the ellipticity of the oil pipe 1 and the installation error.

[0029] refer to Figure 5 and Figure 6 The aforementioned permanent magnet 4 can generate axial displacement under the thrust of liquid. The magnetic field change triggers the magnetic sensor 5. This can be understood as the flow rate reaching a critical value pushing the built-in permanent magnet 4. When the permanent magnet 4 reaches the position triggering the magnetic sensor, the corresponding magnetic induction switch is triggered to open or close. This open or close signal can be used to control the flow of oil in the circuit. The shape of the permanent magnet 4 is not specifically limited in this embodiment; it can be as follows: Figure 7 As shown, a ring structure, a cuboid structure, or other polyhedral structures can be adopted. In some optional embodiments, the permanent magnet 4 can also be a multi-level permanent magnet array, for example, three ring permanent magnets 4 are connected in series with the spring 3 to form a gradient magnetic field. As for the specific type of permanent magnet 4, as long as the cross-sectional area of ​​the permanent magnet 4 is smaller than the cross-sectional area of ​​the oil pipe 1, the liquid flow can be guaranteed.

[0030] by Figure 8 For example, the magnetic sensor 5 can non-contactly sense changes in the magnetic field of the permanent magnet 4 and output an electrical signal that is positively correlated with the flow rate. The sensing surface can be used to sense the magnetic field signal of the permanent magnet 4. The magnetic sensor 5 can output an electrical signal based on the magnetic field signal. The electrical signal can include an electrical signal that feeds back the flow rate, a signal that controls the on / off state of the oil circuit, and a signal that adjusts the flow rate.

[0031] In this embodiment, by linearly converting the flow rate of the liquid in the oil pipe 1 into the compression of the spring 3, the permanent magnet 4 moves axially within the oil pipe 1 to trigger the magnetic field signal of the external magnetic sensor 5, thereby achieving non-contact detection and avoiding direct contact between the sensor element and the liquid. This extends the lifespan of the core components of the sensing device to a certain extent, thus enhancing the reliability of the sensing device.

[0032] Optionally, the spring base 2 is fixedly connected to the inner wall of the oil pipe 1 by bolts. The inner wall of the oil pipe 1 is provided with at least one threaded hole, and the spring base 2 is provided with at least one mounting hole corresponding to the at least one threaded hole. The bolt passes through the mounting hole of the spring base 2 and is screwed into the threaded hole of the inner wall of the oil pipe 1.

[0033] In this embodiment, the threaded holes on the inner wall of the oil pipe 1 can be multiple threaded openings evenly distributed around the circumference of the oil pipe 1. The threaded pair provides axial tightening force, and the inter-thread fit withstands radial shear force, thereby improving shear strength. The spring base 2 is provided with at least one mounting hole corresponding to the at least one threaded hole. In some optional embodiments, the hole opening can be chamfered to avoid stress concentration. The axis of the mounting hole can be kept at a certain distance from the edge of the spring base 2 to ensure the strength of the base. The edge of the mounting hole can also be surface hardened to prevent wear during bolt insertion to a certain extent. The bolt can be used with a spring washer 3 or thread-locking adhesive to achieve an anti-loosening effect under vibration conditions. The type and material of the bolt are not specifically limited in this application embodiment; stainless steel or other corrosion-resistant materials can be used. In some other optional embodiments, a sealing gasket can be added to the contact surface between the bolt head and the spring base 2 to reduce the possibility of liquid leakage.

[0034] Of course, in addition to bolted connections, laser welding can also be used. For example, a continuous annular weld can be provided at the overlap between the flange of the spring base 2 and the inner wall of the oil pipe 1. Alternatively, a two-component epoxy resin can be thickly coated on the annular boss of the spring base 2, and multiple radial lugs can be provided around the spring base 2 to cooperate with the pre-made grooves on the inner wall of the oil pipe 1 to ensure uniform bonding gaps. In addition, clamps or other connection methods can also be used. Different connection methods between the spring base 2 and the inner wall of the oil pipe 1 do not affect the realization of the basic function of the oil pipe 1 sensing device in this application embodiment.

[0035] In this embodiment, the positioning and engagement of the threaded hole and the mounting hole enable rapid and precise assembly with coaxiality, improving assembly efficiency and ensuring reliable connection under various working conditions. The synergistic design of the bolt preload and sealing structure enhances the pressure-bearing capacity to some extent; furthermore, the detachable bolt connection allows for separate replacement of spring 3, reducing maintenance costs to some extent.

[0036] Optionally, the magnetic sensor 5 includes a linear Hall element, an amplifier circuit, and a voltage-frequency converter.

[0037] In this embodiment, when the displacement of the permanent magnet 4 causes a change in magnetic field strength, the aforementioned linear Hall element outputs a mV-level voltage signal, directly converting the change in magnetic field strength into an analog voltage signal. For example, when the permanent magnet 4 compresses the spring by 33mm, the magnetic field strength increases from 50mT to 150mT, and the voltage signal rises from 75mV to 225mV. The aforementioned amplification circuit can be used for signal conditioning, based on an instrumentation amplifier, and bandpass filtering can be used to suppress fluid pulsation noise, thereby reducing power frequency interference. When digital signal output is required, the amplified analog voltage signal can enter a voltage-to-frequency converter to convert the voltage value into a frequency signal. The higher the voltage, the higher the output pulse frequency, achieving a linear mapping between voltage and frequency, facilitating acquisition and processing by digital circuits. According to the design requirements of the magnetic sensor 5, the output electrical signal can be: an analog signal, i.e., an amplified voltage signal, such as a 0-5V voltage signal, directly reflecting the continuous change in magnetic field strength; or a frequency signal converted by the voltage-to-frequency converter, where the frequency indicates the change in magnetic field strength.

[0038] Of course, the magnetic sensor 5 mentioned above can also use other sensing elements besides Hall elements to sense the magnetic field strength, such as fluxgate sensors, reed switches and counters or anisotropic magnetoresistive sensors. The magnetic sensor 5 can also include other circuits or components, as long as they can realize the function of sensing the magnetic field strength. Different types of magnetic sensors 5 do not affect the realization of the basic function of the oil pipe 1 sensing device in this application embodiment.

[0039] In this embodiment, the linear conversion of flow velocity to voltage signal is achieved through the magnetic field-voltage linear conversion characteristic of the linear Hall element. The weak signal output by the Hall element is amplified by the instrument-level signal conditioning of the amplifier circuit, and a certain amount of fluid pulsation noise is filtered out, thereby reducing the detection error. The amplified voltage signal is converted into a frequency signal by the voltage-to-frequency converter, and the signal error rate is reduced by using pulse edge transmission, thereby enhancing the reliability of the flow velocity detection of the sensing device.

[0040] Optionally, the spring 3 is a normally open spring 3 or a normally closed spring 3.

[0041] In this embodiment, the normally open spring 3, in its natural state (i.e., when there is no pressure or external force in the oil circuit), is in an extended state, causing the permanent magnet 4 to move away from the sensing element. At this time, the magnetic field strength generated by the permanent magnet 4 is lower than the detection threshold. The normally closed spring 3, in its natural state, is in a compressed state, with the permanent magnet 4 close to the sensing element, and the magnetic field strength is higher than the detection threshold. The same magnetic induction device can be compatible with both "high pressure alarm" and "low pressure alarm" functions by changing the type of spring 3. By switching the state of spring 3, bidirectional detection of the oil circuit pressure threshold can be achieved. Furthermore, the elastic potential energy of spring 3 can also be used to dynamically buffer flow rate and pressure fluctuations. The built-in spring 3 can be equipped with springs of different elasticity levels, normally open springs, normally closed springs, etc., according to the flow direction of the pipeline and the flow rate of the built-in liquid. The externally mounted magnetic sensor on the pipeline can be set as a normally open or normally closed switch according to the signal requirements. Multiple switches can be set in the overall oil pipe built-in spring magnetic circuit switch to detect the pipeline flow rate level; it can also trigger whether the pipeline is working to perform synchronous pre-processing actions such as start-up.

[0042] Of course, this application embodiment does not impose specific restrictions on the initial form and specific type of spring 3 in the oil circuit. Using normally open spring 3, normally closed spring 3, or spring 3 in other initial forms in the oil circuit does not affect the realization of the basic function of the oil pipe 1 sensing device in this application embodiment.

[0043] Optionally, the spring 3 is made of stainless steel.

[0044] The aforementioned stainless steel material is a corrosion-resistant alloy based on iron, with added alloying elements such as chromium, nickel, and molybdenum. It exhibits good compatibility with most liquids and is not prone to chemical reactions. In oil pipe 1, the chromium in the stainless steel forms a dense oxide film (Cr2O3), effectively resisting liquid corrosion or electrochemical corrosion. This prevents spring 3 from breaking, experiencing performance degradation, or contaminating the oil circuit due to rust, thus extending the service life of spring 3 and improving system reliability. Furthermore, stainless steel possesses high tensile strength and fatigue resistance, capable of withstanding high-frequency pressure fluctuations in the oil circuit, such as the reciprocating compression or tension of spring 3 when linked with permanent magnet 4. It is less prone to plastic deformation or fatigue fracture, ensuring the stability of oil circuit control mechanisms, such as valve opening and closing and the position holding of permanent magnet 4. Stainless steel can also withstand higher temperatures, preventing the softening and failure of ordinary spring 3 steel due to high-temperature annealing, while also inhibiting oxide scale shedding and contamination of the liquid inside oil pipe 1.

[0045] In addition, other materials can be used instead of stainless steel. For example, ordinary spring steel can be used, but the surface can be galvanized, nickel-plated, chromium-plated, or coated with anti-corrosion coatings such as Teflon or Dacromet; or corrosion-resistant alloy materials such as nickel-based alloys or titanium alloys can be used; or engineering plastics such as nylon (PA) and polyetheretherketone (PEEK) or carbon fiber reinforced composite materials can be used to manufacture spring 3.

[0046] Optionally, the spring 3 is a variable stiffness helical spring 3.

[0047] The aforementioned spring 3 is a variable stiffness helical spring 3, meaning that the spring 3 adopts the form of a helical spring 3, but its stiffness, that is, its elastic coefficient, can change with the load or deformation. The variable stiffness characteristic is achieved through non-uniform pitch, such as uneven coil spacing, non-uniform diameter, such as conical or variable diameter helices, or composite material combinations, such as the superposition of materials with different elastic moduli. This causes the effective number of working coils or cross-sectional area of ​​the spring 3 to change dynamically during compression or tension, thus exhibiting nonlinear elastic characteristics.

[0048] In this embodiment, when the permanent magnet 4 is pushed by oil pressure, the variable stiffness spring 3 can provide lower stiffness in the low load stage to avoid response lag due to excessive initial resistance; when the load exceeds the threshold, the stiffness automatically increases to suppress excessive displacement of the permanent magnet 4, realizing intelligent buffering of "soft under light load and stiff under heavy load" and improving system stability, such as preventing impact vibration when valves are opened and closed. Traditional constant stiffness springs 3 are prone to resonance at a fixed frequency, while the variable stiffness characteristic allows the natural frequency of the spring 3 to change with the load, avoiding overlap with the oil circuit pressure pulsation frequency, such as the periodic fluctuation of the pump, reducing vibration noise and fatigue damage risk, and is especially suitable for high-frequency hydraulic systems.

[0049] Of course, other types of springs 3 can be used to replace the variable stiffness helical spring 3. For example, a multi-segment equal stiffness spring 3 can be used in series or nested, and mechanical limiting, such as stops or retainers, can be used to activate different stiffness segments of the spring 3 under different compression strokes. Disc springs 3 can also be stacked and combined, and nonlinear stiffness characteristics can be achieved by changing the stacking method, i.e., parallel, series, or mixed methods. In addition, even during operation, not interfering with the stiffness of the spring 3 will not affect the realization of the basic function of the oil pipe 1 sensing device in this application embodiment.

[0050] Optionally, the spring base 2 is fixedly connected to the inner wall of the oil pipe 1 by an interference fit.

[0051] The aforementioned interference fit between the spring base 2 and the inner wall of the oil pipe 1 can be understood as the outer diameter of the spring base 2 being slightly larger than the inner diameter of the inner wall of the oil pipe 1. Through external force, such as press-fitting, heating the oil pipe 1, or cooling the base, the base is forcibly embedded into the oil pipe 1. Friction is generated by the elastic deformation pressure between the contact surfaces, achieving rigid fixation without fasteners. This fit is a static connection; after assembly, the base and the inner wall of the oil pipe 1 are tightly fitted together without relative displacement.

[0052] In this embodiment, the radial pressure generated by the interference fit can fill the small machining tolerances, thereby reducing the risk of leakage. The interference fit fixing method makes the base and the oil pipe 1 form an integral structure, which improves the anti-loosening ability to a certain extent in high-frequency vibration scenarios and can prevent the spring 3 from falling off due to connection failure, thus avoiding system failure.

[0053] Of course, whether or not an interference fit is used for the fixed connection does not affect the realization of the basic function of the sensing device of the oil pipe 1 in this application embodiment. On the basis of the threaded connection, thread sealant can be applied and tightened, and locked with a metal retaining ring or anti-loosening nut. Alternatively, an annular groove can be machined on the inner wall of the oil pipe 1, and an elastic retaining ring can be set at the end of the spring base 2. During assembly, the retaining ring is compressed and retracts into the oil pipe 1, and after it is in place, it springs open and embeds into the groove to lock.

[0054] Optionally, the permanent magnet 4 is an annular permanent magnet 4, and the annular permanent magnet 4 has at least one axial protrusion on its outer circumference. The inner wall of the oil pipe 1 is provided with at least one guide groove, and the axial protrusion and the guide groove are in sliding fit.

[0055] The aforementioned axial protrusion can be understood as a strip-shaped protrusion extending axially on the outer side of the permanent magnet 4. The cross-section can be rectangular, trapezoidal, or semi-circular. The specific number can be adjusted according to the diameter of the oil pipe 1. This application embodiment does not make specific limitations. The axial groove processed on the inner wall of the oil pipe 1 matches the shape of the protrusion. During assembly, the protrusion is inserted axially along the guide groove to restrict the circumferential rotation of the permanent magnet 4, while allowing it to slide freely along the axial direction.

[0056] The sliding fit of the aforementioned protrusion and guide groove restricts the circumferential rotational freedom of the permanent magnet 4 within a certain range, ensuring that the magnetic field direction is always consistent with the design and avoiding magnetic coupling failure due to rotation. At the same time, the protrusion-guide groove provides a mechanical centering reference, compensates for the radial offset caused by magnetic field eccentricity, and reduces vibration noise caused by magnetic off-center loading. The fit gap between the protrusion and guide groove can also form a labyrinth seal structure, preventing particulate impurities in the hydraulic oil from entering the gap between the permanent magnet 4 and the oil pipe 1, and preventing impurities from getting stuck and affecting sliding.

[0057] In addition, other methods can be used to replace the protrusions and guide grooves; for example, a keyway can be machined on the outer circle of the permanent magnet 4, and a guide key can be installed on the inner wall of the oil pipe 1. The circumferential force is transmitted through the two sides of the key to restrict rotation. Alternatively, elastic claws can be set on the outer side of the permanent magnet 4, and an annular groove can be machined on the inner wall of the oil pipe 1. During assembly, the claws deform under pressure and enter the oil pipe 1, and after reaching their position, they spring into the groove to lock the circumferential direction. A radially magnetized boss can also be set on the outer side of the permanent magnet 4, and soft magnetic material can be embedded at the corresponding position on the inner wall of the oil pipe 1 to achieve circumferential positioning through magnetic attraction, etc.

[0058] Optionally, the permanent magnet 4 is made of neodymium iron boron material.

[0059] The aforementioned neodymium iron boron is a rare earth permanent magnet material with neodymium (Nd), iron (Fe), and boron (B) as its main components. It has a high magnetic energy product, high residual magnetic induction intensity after magnetization, and strong resistance to demagnetization. It is currently the permanent magnet material with the strongest magnetic properties in application.

[0060] The magnetic energy product of neodymium iron boron (NdFeB) is 5-10 times that of ordinary ferrite permanent magnets 4, enabling it to generate a stronger magnetic field in a smaller volume, making it suitable for applications requiring compact structures and strong magnetic forces. In the oil pipe 1, strong magnetic force can ensure a stable connection or seal between the permanent magnet 4 and mating components. Furthermore, due to its high coercivity and strong resistance to demagnetization, NdFeB maintains stable magnetic properties at room temperature or moderate temperatures, and is not easily demagnetized by external magnetic field interference or mechanical vibration. In some optional embodiments, the surface of the permanent magnet 4 can be electroplated or sprayed to further improve its corrosion resistance.

[0061] In addition to neodymium iron boron materials, ferrite permanent magnets 4, AlNiCo permanent magnets 4, or samarium cobalt permanent magnets 4 can also be used. The choice of different materials for permanent magnets 4 does not affect the realization of the basic function of the oil pipe 1 sensing device in this embodiment.

[0062] Optionally, the inner wall of the oil pipe 1 is coated with a polytetrafluoroethylene coating, and the outer surface of the permanent magnet 4 is chrome-plated.

[0063] The aforementioned polytetrafluoroethylene (PTFE) is a polymer material with an extremely low coefficient of friction, strong chemical inertness, resistance to corrosion from strong acids, strong alkalis, and oils, and wide temperature range stability. When coated on the inner wall of the oil pipe 1, it forms a smooth, corrosion-resistant thin film. Chromium plating is achieved by electroplating a layer of metallic chromium (Cr) onto the surface of the permanent magnet 4. The chromium layer possesses high hardness, excellent corrosion resistance, and a mirror-like gloss, protecting the permanent magnet 4 substrate and improving its surface properties.

[0064] Coating with polytetrafluoroethylene can reduce frictional loss during oil flow and improve pipeline transmission efficiency while providing corrosion protection. At the same time, the outer surface of the permanent magnet 4 is chrome-plated. Since the chrome layer is a metal conductor but is relatively thin, it has little impact on the magnetic field distribution of the permanent magnet 4. This can maintain stable magnetic performance while resisting frictional wear between the permanent magnet 4 and the inner wall of the oil pipe 1 or other components during installation and sliding.

[0065] Other coating materials can also be used, such as molybdenum disulfide (MoS2) coating, epoxy resin (EP) coating, or fluorinated ethylene propylene copolymer (FEP), etc.; the surface of the permanent magnet 4 can also be coated with a ceramic coating or hot-dip galvanized instead of chromium plating; of course, even if the inner wall of the oil pipe 1 and the outer surface of the permanent magnet 4 are not processed, it will not affect the realization of the basic function of the oil pipe 1 sensing device in this embodiment of the application.

[0066] In this embodiment, the device includes an oil pipe through which liquid flows; a spring base disposed inside the oil pipe and fixedly connected to its inner wall, the spring base having at least one through hole; a spring, the first end of which is fixedly connected to the spring base; a permanent magnet disposed inside the oil pipe and fixedly connected to the second end of the spring, the permanent magnet moving axially along the oil pipe under liquid pressure, causing the spring to compress, the cross-sectional area of ​​the permanent magnet being smaller than that of the oil pipe; and a magnetic sensor fixedly connected to the outer wall of the oil pipe, the sensing surface of the magnetic sensor being in close contact with the outer wall of the oil pipe. This embodiment linearly converts the flow velocity of the liquid in the oil pipe into spring compression, causing the permanent magnet to move axially within the oil pipe and trigger the magnetic field signal of an external magnetic sensor, achieving non-contact detection. This avoids direct contact between the sensor element and the liquid, extending the lifespan of the core components of the sensing device to some extent, thereby enhancing the reliability of the sensing device.

[0067] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the utility model involved in this application is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

[0068] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this utility model, the other technical features will not be described in detail here.

Claims

1. A tubing induction apparatus, characterized by, The utility model relates to a liquid flow sensor, comprising: a pipe for liquid flow inside; a spring base arranged inside the pipe and fixedly connected with the inner wall of the pipe, the spring base being provided with at least one through hole; a spring having a first end fixedly connected with the spring base; a permanent magnet arranged inside the pipe and fixedly connected with a second end of the spring, the permanent magnet being axially movable along the pipe under the pressure of liquid and driving the spring to be compressed, the cross-sectional area of the permanent magnet being smaller than that of the pipe; a magnetic inductor fixedly connected with the outer wall of the pipe, the inductive surface of the magnetic inductor being tightly attached to the outer wall of the pipe.

2. The apparatus of claim 1, wherein, The spring base and the inner wall of the pipe are fixedly connected by bolts, the inner wall of the pipe is provided with at least one threaded hole, the spring base is provided with at least one mounting hole corresponding to the at least one threaded hole, and the bolts pass through the mounting holes of the spring base and are screwed into the threaded holes of the inner wall of the pipe.

3. The apparatus of claim 2, wherein, The magnetic inductor comprises a linear Hall element, an amplification circuit and a voltage-frequency converter.

4. The apparatus of claim 1, wherein, The spring is a normally open spring or a normally closed spring.

5. The apparatus of claim 2, wherein, The spring is made of stainless steel.

6. The device of any one of claims 1 to 3, wherein, The spring is a variable stiffness coil spring.

7. The device of any one of claims 1 to 3, wherein, The spring base and the inner wall of the pipe are fixedly connected by interference fit.

8. The device of any one of claims 1 to 3, wherein, The permanent magnet is a ring-shaped permanent magnet, the outer circumference of the ring-shaped permanent magnet is provided with at least one axial rib, the inner wall of the pipe is provided with at least one guide groove, and the axial rib and the guide groove are in sliding fit.

9. The apparatus of claim 8, wherein, The permanent magnet is made of neodymium-iron-boron material.

10. The device of any one of claims 1 to 3, wherein, The inner wall of the pipe is coated with a polytetrafluoroethylene coating, and the outer surface of the permanent magnet is chrome-plated.

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