Anti-interference long cable type temperature and humidity sensor easy to disassemble and assemble

Abstract

An anti-interference long cable type temperature and humidity sensor easy to disassemble and assemble comprises a tubular probe shell, the two ends of a four-core double-shielding cable are electrically connected with a probe circuit board and an anti-interference interface module respectively, and the probe circuit board is electrically connected with a thermistor and a humidity sensitive capacitor. One end of the interference removing interface module is respectively connected with two terminals of the thermistor, two terminals of the humidity sensitive capacitor, a cable inner shielding terminal of the four-core double-shielding cable and a cable outer shielding terminal of the four-core double-shielding cable; the other end is respectively connected with the wiring end of the probe shell, the measuring pin of the thermistor, the measuring pin of the humidity sensitive capacitor, the wiring end of the input voltage and a ground wire; when a measuring signal is input into the measuring pin of the humidity-sensitive capacitor, the inner shield of the cable and the measuring pin of the humidity-sensitive capacitor are enabled to be equipotential, so as to eliminate the additional shunt capacitance of the four-core double-shield cable to the positive lead end of the humidity-sensitive capacitor, eliminate the interference caused by the grounding problem of the shell, eliminate the influence of the cable to the core wire, and achieve the purpose of accurately and reliably measuring the temperature and the humidity.

Description

Technical Field

[0001] The invention relates to a temperature and humidity sensor probe, in particular to a long cable type temperature and humidity sensor with simple assembly and disassembly and anti-interference. Background Art

[0002] Temperature and humidity sensors are one of the commonly used sensors in industrial automation process control. As the core component of temperature and humidity sensors, temperature and humidity sensor probes are directly related to the accuracy and stability of temperature and humidity sensor measurement data. When encountering some working conditions where the installation and maintenance space is small and the equipment needs to be centrally controlled, such as monitoring the temperature and humidity of the supply air, fresh air and exhaust air in the ventilation duct in the air-conditioning system, the probe not only needs to have good filtering properties, but also needs to adapt to different ventilation duct diameters and ensure excellent ventilation. Conventional integrated temperature and humidity sensors have technical problems such as poor adaptability, inconvenient disassembly and assembly, and difficult maintenance. Considering the flexibility and maintainability of equipment installation, the sensor and probe are designed separately. According to the usage, only the sensor probe can be installed in the ventilation duct to be tested, and the collected temperature and humidity signals are transmitted to the sensor for processing through a transmission cable. However, the long transmission cable is bound to introduce great interference, affecting the accuracy and stability of the measurement data.

[0003] Considering special occasions such as ships, aerospace, and nuclear power plants, the sensitive components of the temperature and humidity sensor probe use passive devices that can withstand radiation, that is, humidity-sensitive capacitors and PT1000 are selected as humidity and temperature sensitive devices. Generally, the humidity-sensitive capacitor has a capacitance of about 150PF, and a long cable is used to connect the probe to the acquisition circuit. Since the initial capacitance of the humidity-sensitive capacitor is very small, and the parasitic capacitance formed by the sensor and the electronic circuit leads, cable capacitance, and the capacitance of the surrounding conductors is very large, and these capacitances change randomly, the output error jump can reach about 20% after shaking the cable. Summary of the invention

[0004] In view of the problems in the prior art, the present invention provides a long cable type temperature and humidity sensor with simple assembly and disassembly and anti-interference, which is intended to be easy to use in ventilation ducts, and can be easily assembled and disassembled, and has strong adaptability and anti-interference capabilities.

[0005] The invention discloses a long cable type temperature and humidity sensor with simple assembly and disassembly and anti-interference, comprising a tubular probe shell, a probe protective cover fixedly connected to one end of the probe shell, a cable connector fixedly connected to the other end of the probe shell, one end of a four-core double-shielded cable sequentially passes through the cable connector and the probe shell, then passes into the probe protective cover and is electrically connected to a probe circuit board fixedly installed in the probe protective cover, and the other end of the four-core double-shielded cable is electrically connected to an interference elimination interface module; a thermistor and a humidity-sensitive capacitor are arranged on the electrical connection of the probe circuit board, one end of the interference elimination interface module is respectively connected to two wiring terminals of the thermistor and two wiring terminals of the humidity-sensitive capacitor, and an inner shield wiring terminal and an outer shield wiring terminal of the four-core double-shielded cable, and the other end is respectively connected to the wiring terminal of the probe shell, a measuring foot of the thermistor, a measuring foot of the humidity-sensitive capacitor, a wiring terminal of an input voltage and a ground wire; when a measuring signal is input to the measuring foot of the humidity-sensitive capacitor, the inner shield of the cable is made equal in potential to the measuring foot of the humidity-sensitive capacitor.

[0006] Further: the interference removal interface module includes a shell interference removal capacitor C1, a thermistor filter capacitor C2, a humidity-sensitive capacitor interference removal capacitor C3, a fast follower amplifier U1 and a voltage fine-tuning amplifier U2, the same-direction input terminal of the fast follower amplifier U1 is connected to the positive terminal of the humidity-sensitive capacitor, the output terminal of the fast follower amplifier U1 is connected to the same-direction input terminal of the voltage fine-tuning amplifier U2, and the output pin of the voltage fine-tuning amplifier U2 is connected to the shielding terminal inside the cable.

[0007] Further, the voltage fine-tuning amplifier U2 includes an amplifier Q2, the output pin of the amplifier Q2 is connected to the shielded terminal inside the cable through a resistor R3, a branch of the reverse input end of the amplifier Q2 is grounded through a resistor R1, and the other branch of the reverse input end of the amplifier Q2 is connected to its output pin through a resistor R2.

[0008] Furthermore, a potting glue is filled in the probe shell.

[0009] Furthermore, the probe protection cover is made of sintered stainless steel.

[0010] Further, the probe cover is laser welded on the probe shell.

[0011] Further, a threaded joint is movably sleeved on the probe housing, one end of the threaded joint is fitted with the probe housing, a gap is left between the other end of the threaded joint and the probe housing, a clamping ring is sleeved in the gap, the clamping ring and the threaded joint are constrained to rotate by a spline, one end of the clamping ring extends from the gap to form a fixing part, the outer ring of the fixing part is a conical surface, the inner ring of the fixing part is fitted with the probe housing, strip notches are distributed along the circumference of the fixing part, elastic claws are formed between adjacent strip notches, a tightening nut is sleeved on the fixing part, the tightening nut is threadably matched with the threaded joint, the tightening nut cooperates with the conical surface to squeeze the elastic claws and cause the elastic claws to shrink and deform radially, thereby causing the elastic claws of the fixing part to tightly hold the probe housing.

[0012] Further, a set screw is threadedly matched on the threaded joint, and the set screw penetrates through the side wall of the threaded joint and abuts against the probe housing.

[0013] Further, the outer end of the four-core double-shielded cable is connected to the interference removal interface module through a quick-insert component.

[0014] Beneficial effects of the present invention: The probe in the temperature and humidity sensor probe design method adopts a metal shielding structure, the probe cover and the probe shell are made of metal materials, the cable connector and the cable have metal shielding functions, and the plug uses a metal shielding plug, which can effectively eliminate external electromagnetic interference. After being processed by the interference removal interface module, the parallel capacitance attached to the lead end of the humidity-sensitive capacitor by the cable can be eliminated, the interference caused by the grounding problem of the shell can be eliminated, and the influence of the cable on the core wire can be eliminated, so as to achieve the purpose of accurate and reliable measurement of temperature and humidity. The sensitive elements in the temperature and humidity sensor probe design method are all passive devices, which can be used in irradiated scenes, providing richer application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The circuit connection structure of the present invention; Figure 2 The circuit structure of the voltage fine-tuning amplifier U2 in the present invention; Figure 3 It is a schematic cross-sectional view of the temperature and humidity sensor of the present invention; Figure 4 for Figure 3 A magnified view of the structure in the middle A area; Figure 5 It is a schematic cross-sectional structure diagram of the clamping ring in the present invention; Figure 6 This is a schematic diagram of the installation structure of the temperature and humidity sensor on the ventilation duct socket. DETAILED DESCRIPTION

[0016] The present invention is described in detail below in conjunction with the accompanying drawings. The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention. The directional terms such as left, middle, right, top, and bottom in the embodiments of the present invention are only relative concepts or are based on the normal use state of the product, and should not be considered as restrictive.

[0017] A long cable type temperature and humidity sensor with simple disassembly and assembly and anti-interference, such as Figure 1 and Figure 3 As shown, it includes a tubular probe housing 4, one end of which is fixedly connected to a probe protective cover 1, and the other end of which is fixedly connected to a cable connector 5. One end of a four-core double-shielded cable 6 passes through the cable connector 5 and the probe housing 4 in sequence, and then enters the probe protective cover 1 and is electrically connected to a probe circuit board 2 fixedly installed in the probe protective cover 1. The other end of the four-core double-shielded cable 6 is electrically connected to a de-interference interface module 9 through a quick-insert component 7. The temperature and humidity signals are processed by the de-interference interface module 9 and then output; potting glue is filled in the probe housing 4; a thermistor PT1000 and a One end of the humidity-sensitive capacitor interference removal interface module is respectively connected to the two terminals of the thermistor and the two terminals of the humidity-sensitive capacitor, as well as the inner shield terminal and outer shield terminal of the four-core double-shielded cable, and the other end is respectively connected to the terminal of the probe housing, the measuring foot of the thermistor, the measuring foot of the humidity-sensitive capacitor, the terminal of the input voltage and the ground wire; when the measuring foot of the humidity-sensitive capacitor inputs the measurement signal, the inner shield of the cable is made equal to the measuring foot of the humidity-sensitive capacitor to eliminate the additional parallel capacitance of the four-core double-shielded cable on the positive lead end of the humidity-sensitive capacitor, eliminate the interference caused by the grounding problem of the probe housing, and eliminate the influence of the four-core double-shielded cable on the core wire.

[0018] Among them, Figure 1 and Figure 2As shown, the interference removal interface module includes a shell interference removal capacitor C1, a thermistor filter capacitor C2, a humidity-sensitive capacitor interference removal capacitor C3, a fast follower amplifier U1 and a voltage fine-tuning amplifier U2, the same-direction input terminal of the fast follower amplifier U1 is connected to the positive terminal of the humidity-sensitive capacitor, the output terminal of the fast follower amplifier U1 is connected to the same-direction input terminal of the voltage fine-tuning amplifier U2, the output pin of the voltage fine-tuning amplifier U2 is connected to the inner shielding terminal of the cable, the shell interference removal capacitor C1 can eliminate the interference caused when the shell and the sensor ground are not equal in potential, the thermistor filter capacitor C2 can eliminate the interference to the PT1000 measurement pin measurement signal when there is a signal on the inner shield, and the humidity-sensitive capacitor interference removal capacitor C3 can eliminate the additional parallel capacitance of the cable to the negative lead end of the humidity-sensitive capacitor; the voltage fine-tuning amplifier U2 includes an amplifier Q2, the output pin of the amplifier Q2 is connected to the inner shielding terminal of the cable after passing through a resistor R3, a branch of the reverse input terminal of the amplifier Q2 is grounded after passing through a resistor R1, and the other branch of the reverse input terminal of the amplifier Q2 is connected to its output pin after passing through a resistor R2.

[0019] In addition, the probe housing 4 is made of 316L stainless steel, which has the characteristics of small size, fast response, corrosion resistance, and good welding; the probe protective cover 1 is made of sintered stainless steel material, and there are many tiny gaps on the sintered stainless steel material to allow air to enter. The stainless steel has sufficient strength to protect the sensitive devices at the front end and increase the service life of the probe; the probe protective cover 1 is laser welded on the probe housing 4, and has the advantages of low manufacturing cost, high connection strength, and high dimensional accuracy.

[0020] In order to facilitate the fixed connection of the probe housing 4 to the ventilation duct socket, Figure 4 and Figure 5 As shown, a threaded joint 3 is movably sleeved on the probe housing 4, one end of the threaded joint 3 is in contact with the probe housing 4, and a gap is left between the other end of the threaded joint 3 and the probe housing 4, a clamping ring 32 is sleeved in the gap, and the clamping ring 32 and the threaded joint 3 are constrained to rotate by a spline, one end of the clamping ring 32 extends from the gap to form a fixing portion, the outer ring of the fixing portion is a conical surface 321, and the inner ring of the fixing portion is in contact with the probe housing 4, and strip notches 322 are distributed along the circumference of the fixing portion, and elastic claws 323 are formed between adjacent strip notches 322, and a tightening nut 31 is sleeved on the fixing portion, and the tightening nut 31 is threadably matched with the threaded joint 3, and the tightening nut 31 cooperates with the conical surface 321 to squeeze the elastic claws 323 and cause the elastic claws 323 to shrink and deform radially, so that the elastic claws 323 of the fixing portion hug the probe housing 4, and then the threaded joint 3 is positioned on the probe housing 4, combined with Figure 6As shown, the probe housing 4 can be fixedly connected to the ventilation duct seat 8 through a threaded joint; the length of the probe protective cover 1 penetrating into the pipe to be measured can be adjusted to adapt to different ventilation duct diameters and ensure excellent ventilation; a set screw (not shown) is threadedly matched on the threaded joint 3, and the set screw passes through the side wall of the threaded joint and abuts on the probe housing 4. The threaded joint 3 can also be locked on the probe housing 4 through the set screw, realizing double locking of the threaded joint 3 and the probe housing 4, and improving the connection strength and reliability. The probe housing 4 is threadedly matched with the ventilation duct seat 8, and the structure is tight and reliable, and easy to install.

[0021] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A long cable type temperature and humidity sensor with simple assembly and disassembly and anti-interference, characterized in that: The invention comprises a tubular probe shell, one end of which is fixedly connected with a probe protective cover, and the other end of which is fixedly connected with a cable connector. One end of a four-core double-shielded cable passes through the cable connector and the probe shell in sequence, and then passes into the probe protective cover and is electrically connected to a probe circuit board fixedly installed in the probe protective cover, and the other end of the four-core double-shielded cable is electrically connected to an interference elimination interface module; a thermistor and a humidity-sensitive capacitor are arranged on the electrical connection of the probe circuit board; one end of the interference elimination interface module is respectively connected to two wiring terminals of the thermistor and two wiring terminals of the humidity-sensitive capacitor, and an inner shield wiring terminal and an outer shield wiring terminal of the cable of the four-core double-shielded cable, and the other end is respectively connected to a wiring terminal of the probe shell, a measuring foot of the thermistor, a measuring foot of the humidity-sensitive capacitor, a wiring terminal of an input voltage and a ground wire; when a measuring signal is input to the measuring foot of the humidity-sensitive capacitor, the inner shield of the cable is made equal in potential to the measuring foot of the humidity-sensitive capacitor, so as to eliminate the additional parallel capacitance of the four-core double-shielded cable to the positive lead end of the humidity-sensitive capacitor.

2. The long cable type temperature and humidity sensor with easy assembly and disassembly and anti-interference according to claim 1 is characterized in that: The interference removal interface module includes a shell interference removal capacitor C1, a thermistor filter capacitor C2, a humidity-sensitive capacitor interference removal capacitor C3, a fast follower amplifier U1 and a voltage fine-tuning amplifier U2. The same-direction input terminal of the fast follower amplifier U1 is connected to the positive terminal of the humidity-sensitive capacitor, the output terminal of the fast follower amplifier U1 is connected to the same-direction input terminal of the voltage fine-tuning amplifier U2, and the output pin of the voltage fine-tuning amplifier U2 is connected to the shielding terminal inside the cable.

3. The long cable type temperature and humidity sensor with easy assembly and disassembly and anti-interference according to claim 2 is characterized in that: The voltage fine-tuning amplifier U2 includes an amplifier Q2, the output pin of the amplifier Q2 is connected to the shielded terminal inside the cable through a resistor R3, a branch of the reverse input end of the amplifier Q2 is grounded through a resistor R1, and the other branch of the reverse input end of the amplifier Q2 is connected to its output pin through a resistor R2.

4. The long cable type temperature and humidity sensor with easy assembly and disassembly and anti-interference according to claim 1 is characterized in that: The probe housing is filled with potting glue.

5. The long cable type temperature and humidity sensor with easy assembly and disassembly and anti-interference according to claim 1 is characterized in that: The probe protection cover is made of sintered stainless steel.

6. The long cable type temperature and humidity sensor with easy assembly and disassembly and anti-interference according to claim 5 is characterized in that: The probe cover is laser welded to the probe housing.

7. The long cable type temperature and humidity sensor with easy assembly and disassembly and anti-interference according to claim 1 is characterized in that: A threaded joint is movably sleeved on the probe housing, one end of the threaded joint is fitted with the probe housing, and a gap is left between the other end of the threaded joint and the probe housing, a clamping ring is sleeved in the gap, and the clamping ring and the threaded joint are constrained to rotate by splines, one end of the clamping ring extends from the gap to form a fixing part, the outer ring of the fixing part is a conical surface, the inner ring of the fixing part is fitted with the probe housing, strip notches are distributed along the circumference of the fixing part, and elastic claws are formed between adjacent strip notches, and a tightening nut is sleeved on the fixing part, and the tightening nut is threadably matched with the threaded joint, and the tightening nut cooperates with the conical surface to squeeze the elastic claw and cause the elastic claw to shrink and deform radially, so that the elastic claw of the fixing part tightly holds the probe housing.

8. The long cable type temperature and humidity sensor with easy assembly and disassembly and anti-interference according to claim 7 is characterized in that: The threaded joint is threadedly matched with a set screw, which penetrates through a side wall of the threaded joint and abuts against a probe housing.

9. The long cable type temperature and humidity sensor with easy assembly and disassembly and anti-interference according to claim 1 is characterized in that: The outer end of the four-core double-shielded cable is connected to the interference elimination interface module through a quick-insert component.

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