High-precision thermal flowmeter with threaded plug-in temperature probe

Abstract

The application provides a high-precision thermal flowmeter with a threaded plug-in type temperature measuring probe, comprising a cold-end temperature measuring probe, a hot-end speed measuring probe and a pipeline; a fluid channel is formed in the pipeline, and a three-way connector in communication with the fluid channel is arranged at each end of the pipeline; the two three-way connectors are respectively provided with a temperature measuring positioning hole and a speed measuring positioning hole; the cold-end temperature measuring probe is installed in the temperature measuring positioning hole through threaded connection and is used for collecting fluid temperature; the hot-end speed measuring probe is installed in the speed measuring positioning hole through threaded connection and is used for collecting the temperature of heated fluid; and the measuring ends of the cold-end temperature measuring probe and the hot-end speed measuring probe are flush with the inner surface of the fluid channel. The thermal flowmeter of the application adopts an external probe non-invasive structure design, avoids the interference of traditional plug-in type sensors on the flow state of fluid, improves the measurement accuracy, and effectively reduces the risk of component damage caused by foreign matter impact.

Description

Technical Field

[0001] This invention relates to the field of flow meter technology, and more specifically, to a high-precision thermal flow meter employing a threaded insert temperature probe. Background Technology

[0002] Thermal flow meters utilize the physical law of convective heat transfer to measure fluids with low flow rates. Based on the heating power and the temperature relationship between the two probes (temperature and velocity), thermal flow meters can be divided into two measurement modes: constant power and constant temperature difference. In constant power mode, the heater heats the probes at a constant power, and the flow velocity is measured by measuring the temperature difference between the two probes. In constant temperature difference mode, the heater power is adjusted to maintain a constant temperature difference between the two probes, and the fluid velocity is measured by measuring the heating power.

[0003] Thermal flow meters, operating in constant power mode, offer a wider measurement range, are less susceptible to contamination, and can automatically compensate for temperature changes, thus possessing broader development potential. Existing thermal flow meters seal the temperature sensing element and heating element together, forming a velocity sensing element inserted into the center of the pipe. This structure disrupts the fluid flow pattern, interfering with measurement accuracy. Furthermore, the element is easily damaged by foreign objects in the fluid, and its complex structure and large size limit its application scenarios.

[0004] In view of this, the applicant hereby submits this application after studying the existing technology. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a high-precision thermal flow meter using a threaded insert temperature probe, including a cold end temperature probe, a hot end velocity probe, and a pipeline;

[0006] A fluid channel is formed inside the pipe. Two T-connectors communicating with the fluid channel are provided at both ends of the pipe. The two T-connectors are respectively provided with a temperature measurement positioning hole and a speed measurement positioning hole. The cold end temperature measurement probe is installed in the temperature measurement positioning hole through a threaded connection for collecting the fluid temperature. The hot end speed measurement probe is installed in the speed measurement positioning hole through a threaded connection for collecting the temperature of the heated fluid. The measuring ends of the cold-end temperature probe and the hot-end velocity probe are flush with the inner surface of the fluid channel.

[0007] As a further optimization, the pipe and the tee connector are connected by threads, and a combination gasket is installed at the connection to prevent fluid leakage.

[0008] As a further optimization, both the cold end temperature probe and the hot end speed probe include a metal shell, a heat insulation sleeve, and a measurement and control component. The heat insulation sleeve is fitted inside the metal shell, and the measurement and control component is installed inside the heat insulation sleeve. The measurement and control component includes a circuit post, a contact PCB board, a thermally conductive copper post, and a temperature sensing element. The circuit post, the contact PCB board, and the temperature sensing element are electrically connected. The thermally conductive copper post is located at the end closest to the fluid, with its lower end extending into the fluid channel to contact the fluid, and its lower surface is flush with the inner surface of the fluid channel. The temperature sensing element is embedded in the thermally conductive copper post and located at the end closest to the fluid for sensing the fluid temperature. The hot-end speed probe also includes a ceramic heater, which is located at the upper end of the thermally conductive copper post so that the thermally conductive copper post can conduct heat to the fluid.

[0009] As a further optimization, the top of the metal housing is provided with a screw plug for sealing, which seals the top of the heat insulation sleeve and fixes the heat insulation sleeve and the temperature control component in the axial direction.

[0010] As a further optimization, the measurement and control component is installed inside the heat insulation sleeve via a heat insulation bracket, which can be used to isolate heat from being transferred to the circuit.

[0011] As a further optimization, the ceramic heater heats the fluid at a constant power.

[0012] As a further optimization, the heat insulation sleeve is made of PEEK heat insulation material.

[0013] As a further optimization, the fluid channel surface is smooth and has no moving parts to achieve pressure loss-free measurement.

[0014] As a further optimization, a computer communication board is also included, which is connected via Bluetooth to the cold end temperature probe and the hot end velocity probe to collect temperature data from the cold end temperature probe and transmit it to the computer for flow calculation.

[0015] By adopting the above technical solution, the present invention can achieve the following technical effects: This invention discloses a high-precision thermal flow meter employing a threaded insert-type temperature probe. It integrates hot-end and cold-end temperature measurement into two small, detachable probes. Simply match the appropriate threaded connections, and it can be installed on a designated pipeline for flow measurement, eliminating the need for sealed temperature sensing and heating elements inserted into the center of the pipe, as in traditional measurement structures. This design significantly reduces the probe's influence on the fluid flow pattern, improving measurement accuracy. Furthermore, the temperature and velocity sensing elements do not directly contact the fluid; temperature conduction through a heat-conducting copper pillar avoids corrosion of the measuring elements, greatly enhancing reliability. In addition, the flow meter has a simple and compact structure, occupies little space, has a smooth flow channel surface without moving parts, and can adapt to complex operating conditions. It offers advantages such as zero pressure loss and low mechanical wear, effectively reducing the risk of failure and expanding the application prospects of flow meters. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a cross-sectional view of a high-precision thermal flow meter that uses a threaded insert temperature probe. Figure 2 This is a cross-sectional view of the fluid channel; The markings in the diagram are: 1-Metal casing; 2-Screw plug; 3-Rubber gasket; 4-Insulation sleeve; 5-Circuit post; 6-Contact PCB board; 7-Insulation bracket; 8-Ceramic heater; 9-Heat-conducting copper pillar; 10-PT1000 temperature sensing element; 11-Pipe; 12-Tee connector; 13-Sealing ring; 14-Combination gasket; 15-Temperature measuring positioning hole; 16-Fluid channel; 17-Velocity measuring positioning hole. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0019] Example Please see Figure 1 An embodiment of the present invention provides a high-precision thermal flow meter using a threaded insert temperature probe, comprising a cold-end temperature probe, a hot-end velocity probe, a tee connector 12, and a pipe 11.

[0020] A fluid channel 16 is formed within the pipe 1. Two T-joints 12, communicating with the fluid channel 16, are connected to both ends of the pipe 1. Each T-joint 12 has a temperature measurement positioning hole 15 and a velocity measurement positioning hole 17. A cold-end temperature probe is threadedly installed in the temperature measurement positioning hole 15 to collect the cold-end temperature value. A hot-end velocity probe is installed in the velocity measurement positioning hole 17 to collect the hot-end temperature value. The measuring ends of the cold-end temperature probe and the hot-end velocity probe are flush with the inner surface of the fluid channel to avoid interfering with the fluid flow pattern and to prevent foreign objects in the fluid from damaging the components, thus improving the measurement accuracy for low flow rates.

[0021] Both the cold-end temperature probe and the hot-end velocity probe include a metal shell 1, a heat-insulating sleeve 4, and a measurement and control component. Specifically, the bottom of the metal shell 1 has an external thread, and the temperature positioning hole 15 and the velocity positioning hole 17 have internal threads. The cold-end temperature probe and the hot-end velocity probe are respectively threaded to the tee connector 12 through the metal shell 1. A sealing ring 13 is provided at the connection between the metal shell 1 and the tee connector 12 to prevent fluid leakage. The heat-insulating sleeve 4 is fitted inside the metal shell 1. A sealing ring 13 is provided on the connection end face of the metal shell 1 and the heat-insulating sleeve 4 for sealing. A cavity for installing the measurement and control component is formed inside the heat-insulating sleeve 4. A screw plug 2 is provided on the top of the metal shell 1 for sealing. The screw plug 2 seals the top of the heat-insulating sleeve 4 and also axially fixes the heat-insulating sleeve 4 and the measurement and control component. A rubber gasket 3 is provided at the joint between the heat-insulating sleeve 4 and the screw plug 2 for further sealing. The measurement and control component is fixedly installed inside the heat insulation sleeve 4 via a heat insulation bracket 7. Both the heat insulation sleeve 4 and the heat insulation bracket 7 can be made of PEEK heat insulation material. The measurement and control component includes a circuit post 5, a PCB circuit board, a thermally conductive copper post 9, and a PT1000 temperature sensing element 10. The circuit post 5, the PCB circuit board, and the PT1000 temperature sensing element 10 are electrically connected. The thermally conductive copper post 9 is located at the end closest to the fluid, and its lower end extends to the inner surface of the fluid channel 16 to contact the fluid for heat conduction. The lower end face of the thermally conductive copper post 9 is basically flush with the inner surface of the fluid channel to avoid interference with the fluid flow pattern. The PT1000 temperature sensing element 10 is embedded inside the thermally conductive copper post 9, close to the fluid end, for measuring the fluid temperature. Embedding the temperature sensing element inside the thermally conductive copper post 9 avoids direct contact between the temperature sensing element and the fluid, preventing corrosion, wear, and other damage to the temperature sensing element. Among them, the circuit pillar 5 and the PCB circuit board are located on the upper end of the heat insulation bracket 7, and the heat-conducting copper pillar 9 is located on the lower end of the heat insulation bracket 7 to prevent the axial transfer of heat.

[0022] The hot-end speed probe also includes a ceramic heater 8, which is located on the upper end of the heat-conducting copper pillar 9 for heating the fluid. The heat insulation bracket 7 separates the ceramic heater 8 from the circuit pillar 5 and the PCB circuit board, preventing the heat generated by the ceramic heater 8 from being transferred to the circuit pillar 5. The ceramic heater 8 is tightly fitted between the heat insulation bracket 7 and the heat-conducting copper pillar 9, heating the copper pillar 9 with a constant power. The copper pillar 9 then conducts the heat to the fluid, and the PT1000 temperature sensing element 10 measures the temperature of the fluid after heating.

[0023] Please see Figure 2 The inner surface of the fluid channel 16 is smooth and has no moving parts, thus enabling pressure loss-free measurement. A combination gasket 14 is installed at the connection between the pipe 11 and the tee connector 12 to prevent fluid leakage. The through hole of the tee connector 12 has the same diameter as the hole of the pipe 11 to ensure that the fluid flow is not affected.

[0024] This application discloses a high-precision thermal flow meter employing a threaded insert-type temperature probe. It also includes a computer communication board, which is connected via Bluetooth to both the cold-end temperature probe and the hot-end velocity probe. This computer communication board collects temperature data from the cold-end and hot-end temperature probes and transmits it to the computer for flow rate calculation. The computer communication board collects temperature data from the cold-end and hot-end temperature probes in real time, and after obtaining the temperature difference, calculates the flow rate using a formula relating flow rate to temperature difference.

[0025] This application discloses a high-precision thermal flow meter employing a threaded insert-type temperature probe. The external probe, non-invasive design, ensures that the measuring ends of the cold-end temperature probe and the hot-end velocity probe are flush with the inner surface of the fluid channel 16, avoiding interference from traditional insert-type sensors and thus improving measurement accuracy. The cold-end temperature probe and the hot-end velocity probe are respectively fixed to the positioning holes on the tee connector 12 via threaded connections. An integrated heating module and thermal insulation structure effectively reduce the risk of component damage due to foreign object impact and temperature measurement errors caused by heat loss. Its compact measurement and control chamber design, combined with modular assembly, reduces the device size, simplifies the overall structural layout, and expands its application scenarios in confined spaces or complex pipelines.

[0026] The working principle of a high-precision thermal flow meter using a threaded insert temperature probe according to an embodiment of the present invention is as follows: When the fluid flows through the cold-end temperature probe, the heat-conducting copper column 9 exchanges heat with the fluid, and the PT1000 temperature sensing element 10 collects the cold-end temperature value Tc of the fluid. As the fluid continues to flow through the hot-end velocity probe, the ceramic heater 8 heats the heat-conducting copper column 9 at a constant power. The heat-conducting copper column 9 conducts heat to the fluid in contact with it, causing localized heating of the fluid. When the temperature at the bottom of the hot-end velocity probe reaches thermal equilibrium with the temperature of the heated fluid, the temperature of the hot-end velocity probe remains constant, and the PT1000 temperature sensing element 10 collects the hot-end temperature value Th.

[0027] The hot-end velocity probe is heated by a ceramic heater 8 at a constant power while being cooled by the fluid. The heat dissipation power of the fluid cooling is inversely correlated with the temperature difference ΔT (the difference between the hot-end temperature Th and the cold-end temperature Tc). When the cooling power is equal to the electrical power of the ceramic heater 8, the temperature of the hot-end velocity probe stabilizes at a value higher than the fluid temperature. Based on the set heating power P and the collected hot-end velocity probe temperature value Th and cold-end temperature probe temperature value Tc, the temperature difference ΔT is calculated, and the flow rate per unit time is measured. Through experiments, multiple sets of flow rates and temperature differences are obtained, and the one-to-one correspondence between the flow rate and the measured temperature difference can be derived through calculation. The fluid velocity can be calculated based on the relationship, and the corresponding flow rate can be obtained by obtaining different temperature differences. Experimental results show that the high-precision thermal flow meter of the present invention, using a threaded insert temperature probe, can achieve a flow rate of 1-15 m³ / h under a constant heating power of 1000 mW. 3 For flow rate measurement per day, the theoretical minimum resolution is 0.025 m. 3 / d, within the applicable range of the existing relationship between flow rate and temperature difference, the average error between the theoretical calculation value and the experimental calibration is 3.66%. It should be noted that the relationship between the flow rate and temperature difference is existing technology, and this invention does not involve the improvement of the algorithm. Therefore, the specific algorithm will not be described here.

[0028] Another major advantage of this flowmeter lies in its compact design and easy installation. The measurement and control chamber, composed of a metal housing 1, screw plug 2, rubber gasket 3, and heat-insulating sleeve 4, not only protects the internal electronic components but also makes the entire device compact, facilitating installation in various space-constrained environments. The integrated heating module and temperature measurement device, consisting of a ceramic heater 8, a thermally conductive copper column 9, and a PT1000 temperature sensing element 10, enable the flowmeter to respond quickly to changes in fluid velocity, improving the real-time performance of the measurement.

[0029] Compared to traditional flow meters, this design reduces pressure loss and energy consumption, while eliminating the need for complex installation and maintenance procedures, thus lowering overall costs. Therefore, this high-precision thermal flow meter employing a threaded insert temperature probe not only represents a breakthrough in technical performance but also demonstrates significant economic efficiency and practicality in real-world applications, providing an efficient and reliable solution for the field of flow measurement.

[0030] This invention discloses a high-precision thermal flow meter employing a threaded insert-type temperature probe. The flow meter utilizes a detachable small probe structure, with the cold-end temperature probe and the hot-end velocity probe respectively threadedly connected to the temperature positioning hole 15 and velocity positioning hole 17 on the tee connector 12. This avoids the traditional structure of sealing the temperature sensing element and heating element before inserting them into the center of the pipe. This design does not disrupt the fluid flow pattern, reduces interference with measurement accuracy, and lowers the risk of damage to the temperature and velocity sensing elements from foreign objects in the fluid. Furthermore, the structure is relatively simple and the size is small, expanding the application scenarios of the flow meter.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-precision thermal flow meter employing a threaded insertion-type temperature probe, characterized in that, This includes cold-end temperature probes, hot-end velocity probes, and pipelines; A fluid channel is formed inside the pipe. Two T-connectors communicating with the fluid channel are provided at both ends of the pipe. The two T-connectors are respectively provided with a temperature measurement positioning hole and a speed measurement positioning hole. The cold end temperature measurement probe is installed in the temperature measurement positioning hole through a threaded connection for collecting the fluid temperature. The hot end speed measurement probe is installed in the speed measurement positioning hole through a threaded connection for collecting the temperature of the heated fluid. The measuring ends of the cold-end temperature probe and the hot-end velocity probe are flush with the inner surface of the fluid channel.

2. The high-precision thermal flow meter as described in claim 1, characterized in that, The pipe is connected to the tee fitting by threads, and a combination gasket is installed at the connection to prevent fluid leakage.

3. The high-precision thermal flow meter as described in claim 1, characterized in that, Both the cold end temperature probe and the hot end speed probe include a metal shell, a heat insulation sleeve, and a measurement and control component. The heat insulation sleeve is fitted inside the metal shell, and the measurement and control component is installed inside the heat insulation sleeve. The measurement and control component includes a circuit post, a contact PCB board, a thermally conductive copper post, and a temperature sensing element. The circuit post, the contact PCB board, and the temperature sensing element are electrically connected. The thermally conductive copper post is located at the end closest to the fluid, with its lower end extending into the fluid channel to contact the fluid, and its lower surface is flush with the inner surface of the fluid channel. The temperature sensing element is embedded in the thermally conductive copper post and located at the end closest to the fluid for sensing the fluid temperature. The hot-end speed probe also includes a ceramic heater, which is located at the upper end of the thermally conductive copper post so that the thermally conductive copper post can conduct heat to the fluid.

4. The high-precision thermal flow meter as described in claim 3, characterized in that, The top of the metal casing is provided with a screw plug for sealing. The screw plug seals the top of the heat insulation sleeve and fixes the heat insulation sleeve and the temperature control component in the axial direction.

5. The high-precision thermal flow meter as described in claim 3, characterized in that, The measurement and control components are installed inside the heat insulation sleeve via a heat insulation bracket, which can be used to isolate heat from being transferred to the circuit.

6. The high-precision thermal flow meter as described in claim 3, characterized in that, The ceramic heater heats the fluid at a constant power.

7. The high-precision thermal flow meter as described in claim 1, characterized in that, The fluid channel has a smooth surface and no moving parts to achieve pressure loss-free measurement.

8. The high-precision thermal flow meter according to any one of claims 3 to 7, characterized in that, The heat insulation sleeve is made of PEEK heat insulation material.

9. The high-precision thermal flow meter according to any one of claims 1 to 7, characterized in that, It also includes a computer communication board, which is connected via Bluetooth to the cold end temperature probe and the hot end velocity probe to collect temperature data from the cold end temperature probe and transmit it to the computer for flow calculation.

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