Photoionization gas sensor and portable photoionization gas detector

Abstract

The utility model provides a photoionization gas sensor and a portable photoionization gas detector, the photoionization gas sensor is characterized in that an upper gas chamber cover, an electrode circuit board, a lower gas chamber cover, a switching circuit board and an ultraviolet lampshade are fixedly connected through conductive bolts to form a closed cavity, and the ultraviolet lampshade is fixedly connected with an ionization chamber; meanwhile, the conductive bolts can serve as wires to be connected with a collecting electrode on the electrode circuit board and the control circuit board, so that the space is saved, and the electrical connection is more stable; the control circuit board is electrically connected with the conductive bolt and the ultraviolet lamp control panel by using the FPC flexible flat cable, so that the complexity of electrical connection is further reduced; meanwhile, the gas passage is arranged from top to bottom, so that the space of the ionization chamber can be utilized to the maximum extent, the irradiation area is increased while the ultraviolet lamp is prevented from irradiating the collecting electrode, the gas reaction is more sufficient, and the detection efficiency is further improved.

Description

Technical Field

[0001] The utility model relates to the field of gas detection, in particular to a photoionization gas sensor and a portable photoionization gas detector. Background Art

[0002] A variety of volatile organic gases are generated during industrial production. The types of gases are numerous and the concentrations vary, but they all cause great damage to the environment. Effective monitoring measures should be taken to detect gases in key emission pipelines to ensure that the emission gases meet relevant environmental protection standards.

[0003] Photo ionization detector (PID) is a highly sensitive and widely used detector that can detect volatile organic compounds (VOC) and other toxic gases from extremely low concentrations of 10ppb (parts per billion) to higher concentrations of 10000ppm (1%). It has been widely used in industrial safety, environmental protection testing and other fields.

[0004] The invention patent with the publication number CN111855850 A provides a portable photoionization detector, which designs a cylindrical ultraviolet lampshade for installing a cylindrical ultraviolet lamp, installs a base at the bottom of the ultraviolet lampshade, installs an electrode plate at the bottom of the base, and the electrode is installed in the space surrounded by the base, the electrode plate and the isolation sheet. The isolation sheet has a hole for introducing ultraviolet light. The two electrode sheets are arranged in a ring, and the sample gas passes through the middle annular space and fills the ionization chamber. The ionized and broken electrons and ions pass through the middle of the annular electrode and move toward the two electrode sheets. This structure greatly improves the integration of the photoionization detector, and the volume can be reduced as much as possible, making it portable and applicable to more diverse scenarios. However, the electrode sheet and the control circuit board are connected in the form of wires, which has the disadvantage of complex circuits; and once a component fails, it is difficult to quickly replace the component.

[0005] In order to solve the above problems, people have been seeking an ideal technical solution. Summary of the invention

[0006] The utility model aims to address the deficiencies of the prior art and thus provide a light ionization gas sensor and a portable light ionization gas detector which do not require wires.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a photoionization gas sensor, comprising a sensor housing, an ionization chamber, an ultraviolet lamp, an ultraviolet lamp control board and a control circuit board, wherein an air inlet and an air outlet are respectively arranged at both ends of the sensor housing, and the ionization chamber, the ultraviolet lamp, the ultraviolet lamp control board and the control circuit board are arranged in the sensor housing;

[0008] The ionization chamber comprises an upper gas chamber cover, an electrode circuit board and a lower gas chamber cover, wherein two collecting electrodes are arranged in parallel on the electrode circuit board; four bolt holes are arranged on the upper gas chamber cover and the lower gas chamber cover respectively, and four conductive holes are arranged on the electrode circuit board corresponding to the conductive bolts, wherein two conductive holes are electrically connected to the two collecting electrodes respectively; an irradiation window is arranged at the center of the lower gas chamber cover;

[0009] An air inlet hole is arranged on the upper part of the upper air chamber cover corresponding to the air inlet, and the air inlet hole is communicated with the air inlet; a vent hole is arranged on the electrode circuit board corresponding to the air inlet hole, and an air outlet hole is arranged on the lower part of the lower air chamber cover symmetrically with the center of the air inlet hole, and the air outlet is communicated with the air outlet hole;

[0010] A transfer circuit board is fixedly connected to the side of the lower air chamber cover facing away from the upper air chamber cover, and four conductive connecting pieces corresponding to the conductive bolts are arranged on the transfer circuit board I, and an irradiation through hole is also arranged on the transfer circuit board corresponding to the irradiation window;

[0011] The ultraviolet lamp is arranged in the ultraviolet lamp cover corresponding to the irradiation window, and a high-voltage excitation electrode for applying high voltage to the ultraviolet lamp is also arranged inside the ultraviolet lamp cover, and the end of the ultraviolet lamp cover close to the lower air chamber cover is provided with mounting holes corresponding to four conductive connectors; the upper air chamber cover, the electrode circuit board, the lower air chamber cover, the adapter circuit board and the ultraviolet lamp cover are fixedly connected by conductive bolts, bolt holes, conductive holes and mounting holes to form a closed cavity;

[0012] The ultraviolet lamp control board is arranged on one side of the ultraviolet lamp cover, and the ultraviolet lamp control board is electrically connected to the high-voltage excitation electrode;

[0013] The control circuit board is arranged on the other side of the ultraviolet lamp cover, and the control circuit board is electrically connected to four conductive connectors and the ultraviolet lamp control board through FPC flexible flat cables; two conductive bolts are also connected to two collecting electrodes through the conductive holes.

[0014] Preferably, the conductive connecting member is a conductive sleeve, and the conductive bolt is fixed in the conductive sleeve after passing through the bolt hole of the upper air chamber cover, the conductive hole of the electrode circuit board and the bolt hole of the lower air chamber cover.

[0015] Preferably, the conductive bolt is connected to the conductive sleeve by threaded fixing or plug-in fixing.

[0016] The present application also provides a portable photoionization gas detector, a housing, and a photoionization gas sensor, a complete mainboard, and an air pump arranged in the housing, wherein the photoionization gas sensor is the aforementioned photoionization gas sensor; wherein the air inlet of the photoionization gas sensor is located outside the housing, serving as the air inlet of the photoionization gas detector;

[0017] An exhaust port is provided at the end of the housing away from the air inlet, and the exhaust port is connected to the air outlet of the photoionization gas sensor through an air guide pipe and the air pump;

[0018] The control circuit boards of the air pump and the photoionization gas sensor are respectively connected to the main board of the whole machine.

[0019] Preferably, the portable photoionization gas detector also includes an air pump driving circuit, and the air pump driving circuit is electrically connected to the mainboard of the whole device and is used to drive the air pump to work.

[0020] The utility model has substantial characteristics and progress compared with the prior art. Specifically, the utility model uses conductive bolts to fix the upper air chamber cover, the electrode circuit board, the lower air chamber cover, the adapter circuit board and the ultraviolet lamp cover to form a closed cavity, and fixes the ultraviolet lamp cover to the ionization chamber. The detachable connection method is convenient for the replacement of any device; at the same time, the conductive bolts can be used as wires to connect the collecting electrode and the control circuit board on the electrode circuit board, which saves space and makes the electrical connection more stable; FPC soft cables are used to respectively realize the electrical connection between the control circuit board and the conductive bolts and the ultraviolet lamp control board, further reducing the complexity of the electrical connection; at the same time, the gas passage is arranged from top to bottom, which can maximize the use of the space in the ionization chamber, avoid the ultraviolet lamp irradiating the collecting electrode while increasing the irradiation area, so that the gas reaction is more sufficient, thereby improving the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the photoionization gas sensor of the utility model.

[0022] Figure 2 This is a control principle diagram of the photoionization gas sensor of the utility model.

[0023] Figure 3 It is a structural schematic diagram of the utility model photoionization gas detector.

[0024] Figure 4 It is a circuit diagram of the air pump driving circuit diagram of the utility model.

[0025] In the figure: 1. upper end cover; 2. conductive bolt; 3. upper air chamber cover; 4. electrode circuit board; 5. collecting electrode; 6. collecting electrode; 7. nut; 8. sealing gasket; 9. lower air chamber cover; 10. adapter circuit board; 11. conductive sleeve; 12. circuit board wiring assembly I; 13. ultraviolet lamp; 14. compression spring; 15. control circuit board; 16. circuit board wiring assembly II; 17. ultraviolet lamp cover; 18. ultraviolet lamp control board; 19. air guide tube; 20. PCB terminal board; 21. O-ring; 22. shell sleeve; 23. shell; 24. water trap filter; 25. display screen; 26. buzzer; 27. LED lamp; 28. ionization chamber; 29. ​​bias electrode; 30. air pump; 31. air pump drive circuit; 32. composite alarm module. DETAILED DESCRIPTION

[0026] The technical solution of the utility model is further described in detail below through specific implementation methods.

[0027] Example 1

[0028] This embodiment provides a photoionization gas sensor, such as Figure 1-2 As shown, it includes a sensor housing, an ionization chamber 28, an ultraviolet lamp 13, an ultraviolet lamp control board 18 and a control circuit board 15. An air inlet and an air outlet are respectively provided at both ends of the sensor housing. The ionization chamber 28, the ultraviolet lamp 13, the ultraviolet lamp control board 18 and the control circuit board 15 are arranged in the sensor housing.

[0029] In a specific implementation, the sensor housing includes an upper end cover 1 and a housing sleeve 22 , and the upper end cover 1 is screwed onto one end of the housing sleeve 22 via an O-ring 21 .

[0030] The ionization chamber 28 is a flat cylindrical structure, including an upper air chamber cover 3 and a lower air chamber cover 9. An electrode circuit board 4 is also provided in the ionization chamber 28, and two collecting electrodes 6 are provided in parallel on the electrode circuit board 4; wherein the collecting electrode 5 is a positive electrode for absorbing particles with a negative charge sign after being ionized by the ultraviolet lamp 13; and the collecting electrode 6 is a negative electrode for absorbing particles with a positive charge sign after being ionized by the ultraviolet lamp 13.

[0031] An air inlet and an air outlet are respectively provided at both ends of the sensor housing. Specifically, an air inlet is provided on the upper end cover 1, and an air outlet is provided on the housing sleeve 22. An air inlet hole is provided on the upper portion of the upper air chamber cover 3 corresponding to the air inlet, and the air inlet hole is connected with the air inlet; an air vent is provided on the electrode circuit board 4 corresponding to the air inlet hole, and an air outlet symmetrical with the center of the air inlet hole is provided on the lower portion of the lower air chamber cover 9, and the air outlet is connected with the air outlet through an air guide pipe 19.

[0032] In this way, the air inlet, the air inlet hole on the upper air chamber cover 3, the air vent on the electrode circuit board 4, the air outlet hole on the lower air chamber cover 9, and the air outlet constitute a one-way air path; the sampling gas flows through the sensor along the one-way air path for gas concentration detection.

[0033] And because the ionization chamber 28 is a flat cylindrical space, the radial distance is greater than the axial distance. In this embodiment, the gas channel in the ionization chamber 28 is set to be parallel to the radial direction of the ionization chamber 28 from top to bottom, that is, a radial gas path. Therefore, the longest gas channel is ensured in the limited ionization space, avoiding direct ultraviolet light to the electrode while increasing the irradiation area of ​​the ultraviolet lamp 13, thereby improving the detection efficiency.

[0034] Four bolt holes are respectively provided on the upper air chamber cover 3 and the lower air chamber cover 9, and four conductive holes are provided on the electrode circuit board 4 corresponding to the conductive bolts 2, wherein two conductive holes are respectively electrically connected to two collecting electrodes 6; it can be understood that in order to reduce the influence of corrosive gas on the electrode circuit board 4, the electrode circuit board 4 adopts gold plating and other processes.

[0035] It can be understood that a sealing gasket 8 is also provided in the ionization chamber 28 .

[0036] A transfer circuit board 10 is fixedly connected to the side of the lower air chamber cover 9 facing away from the upper air chamber cover 3 , and four conductive connecting members corresponding to the conductive bolts 2 are arranged on the transfer circuit board 10I.

[0037] In one embodiment, the conductive connecting member is a conductive sleeve 11, and the conductive bolt 2 is fixed in the conductive sleeve 11 after passing through the bolt hole of the upper air chamber cover 3, the conductive hole of the electrode circuit board 4 and the bolt hole of the lower air chamber cover 9.

[0038] In one embodiment, the conductive bolt 2 is a structure with a threaded upper end and a smooth lower end. When in use, the upper air chamber cover 3 and the electrode circuit board 4 are fixedly connected by using a nut 7 to cooperate with the thread on the upper end of the conductive bolt 2, and the lower end of the conductive bolt 2 is inserted into the conductive sleeve 11 through the through hole of the lower air chamber cover 9 in turn to achieve electrical connection with the conductive sleeve 11.

[0039] In another embodiment, the conductive bolt 2 is a fully threaded structure. When in use, the upper air chamber cover 3 is fixedly connected to the electrode circuit board 4 by utilizing the nut 7 to cooperate with the thread on the upper end of the conductive bolt 2, and the lower end of the conductive bolt 2 is threadedly connected to the conductive sleeve 11 after passing through the through hole of the lower air chamber cover 9 in turn, thereby achieving electrical connection with the conductive sleeve 11 and further strengthening the fixed connection between the adapter circuit board 10 and the lower air chamber cover 9.

[0040] Furthermore, an irradiation window is provided at the center of the lower air chamber cover 9 corresponding to the ultraviolet lamp 13; an irradiation through hole is provided on the adapter circuit board 10 corresponding to the irradiation window; the ultraviolet lamp 13 is provided in the ultraviolet lamp cover 17 corresponding to the irradiation window, and a high-voltage excitation electrode for applying high voltage to the ultraviolet lamp 13 is also provided inside the ultraviolet lamp cover 17; the ultraviolet lamp cover 17 is provided with mounting holes at the end close to the lower air chamber cover 9 corresponding to four conductive connecting parts.

[0041] When in use, the upper air chamber cover 3, the electrode circuit board 4, the lower air chamber cover 9, the adapter circuit board 10 and the ultraviolet lamp cover 17 are fixedly connected through the conductive bolts 2, bolt holes, conductive holes and mounting holes to form a closed cavity.

[0042] And because the ultraviolet lamp cover 17 is fixedly connected to the lower air chamber cover 9 of the ionization chamber 28, when the ultraviolet lamp 13 is fixed to the ultraviolet lamp cover 17, it is equivalent to that the ultraviolet lamp 13 is fixedly connected to the ionization chamber 28, thereby reducing the reduction of light due to the displacement of the ultraviolet lamp 13 and the irradiation window, resulting in low photoionization efficiency.

[0043] It can be understood that in a specific implementation, an internal thread can be set in the mounting hole, and an external thread can be set outside the conductive connector. The conductive connector is threadedly connected to the mounting hole to facilitate the disassembly and installation of the ultraviolet lamp cover 17 and the adapter circuit board 10.

[0044] Preferably, the high-voltage excitation electrodes are two annular copper rings, which are bonded to the inner wall of the ultraviolet lamp cover 17 by epoxy resin to apply a high voltage between 1000-2000V to the ultraviolet lamp 13 to excite the ultraviolet lamp 13 to emit ultraviolet light.

[0045] Furthermore, the lamp body of the ultraviolet lamp 13 is made of glass, and a plurality of inert gases of different proportions are arranged in the lamp cavity, and the output window is sealed with lithium fluoride crystals. The present embodiment uses an ultraviolet lamp 13 of 10.6eV specification, and the light emitted by the ultraviolet lamp 13 can ionize most organic gases with an ionization potential lower than 10.6eV. When the ultraviolet light of 10.6eV emitted by the ultraviolet lamp 13 irradiates the sampled gas, the sampled gas is ionized to form electrons and ions.

[0046] It should be noted that the lower gas chamber cover 9 is made of opaque material, so the ultraviolet light can only enter the ionization chamber 28 from the irradiation window on the lower gas chamber cover 9. And the diameter of the irradiation window is smaller than the collecting electrode 6. Such a design can ensure that the ultraviolet light irradiates the sampled gas flowing through the gas path, while preventing the ultraviolet light from directly irradiating the collecting electrode 6, causing the photoelectric effect on the collecting electrode 6, and reducing the phenomenon of smaller collected current due to the recombination of electrons generated by the photoelectric effect with positive ions near the electrode.

[0047] Furthermore, in order to facilitate the removal of the ultraviolet lamp 13, the bottom of the ultraviolet lamp 13 is also arranged at the bottom of the ultraviolet lamp cover 17 through a compression spring 14. When the lower air chamber cover 9 is opened, under the action of the compression spring 14, the ultraviolet lamp 13 is ejected from the inside of the ultraviolet lamp cover 17, which facilitates the removal and replacement of the ultraviolet lamp 13.

[0048] The ultraviolet lamp control board 18 is disposed on one side of the ultraviolet lamp cover 17 , and the ultraviolet lamp control board 18 is electrically connected to the high-voltage excitation electrode.

[0049] The control circuit board 15 is arranged on the other side of the ultraviolet lamp cover 17, and the control circuit board 15 is electrically connected to the ultraviolet lamp control board 18 with four conductive connectors through FPC flexible cables; two of the conductive bolts 2 are also connected to the two collecting electrodes 6 through the conductive holes, and are used to convert the tiny current on the collecting electrode 6 into a voltage, and amplify the voltage and convert it into a signal that can be detected by the processor; the remaining two conductive bolts 2 are controlled by the control circuit board 15 and serve as bias electrodes 29 to provide a 120V high-voltage electric field to form an ionizing electric field.

[0050] In a specific implementation, a circuit board cable assembly I 12 is provided on the adapter circuit board 10, one end of the circuit board cable assembly I 12 is typically connected to four conductive connectors, and the other end is used to connect an FPC flexible cable; similarly, a circuit board cable assembly II 16 for connecting an FPC flexible cable is provided on the control circuit board, and the electrical connection between the adapter circuit board 10 and the control circuit board is achieved through the FPC flexible cable.

[0051] It can be understood that when the conductive bolt 2 fixes the ionization chamber 28 with the ultraviolet lamp 13, it acts as a bias electrode 29 to generate a bias electric field so that the particles ionized by the ultraviolet lamp 13 move under the action of the bias electric field, and also acts as a conductor or wire to electrically connect the current on the collecting electrode 6 to the control circuit board 15 through the conductive sleeve 11 and the FPC soft cable in turn, eliminating the need for wire settings, making the circuit indirect and the electrical connection more stable.

[0052] In addition, the control circuit board 15 and the ultraviolet lamp control board 18 are respectively arranged on both sides of the ultraviolet lamp 13, which can effectively utilize the space on both sides of the ultraviolet lamp 13; the ultraviolet lamp control board 18 and the control circuit board 15 are electrically connected through an FPC soft cable. The FPC cable is small in size and light in weight, can meet the requirements of miniaturization and mobility, and can be flexibly bent, while reducing the presence of flying wires inside the photoionization gas sensor, making the electrical connection tighter and more stable.

[0053] Working principle: Under the action of the control circuit board 15 and the ultraviolet lamp control board 18, the high voltage excitation electrode excites the ultraviolet lamp 13 to emit ultraviolet light, and enters the ionization chamber 28 through the irradiation window;

[0054] An air pump 30 is arranged on the outside of the air outlet, and the external sampling gas is pumped in from the air inlet in sequence by the air pump 30, and flows into the ionization chamber 28 through the air inlet hole on the upper air chamber cover 3 and the air vent on the electrode circuit board 4 in sequence, and flows out through the air outlet hole on the lower air chamber cover 9 and the air outlet.

[0055] Among them, after entering the ionization chamber 28, the sampled gas absorbs ultraviolet light energy and becomes ionized, and is ionized into positive and negative ions. It is deflected under the bias voltage generated by the two conductive bolts 2 and is absorbed by the collecting electrode 6, thereby forming a weak current on the collecting electrode 6, and is sent to the control circuit board 15 through the remaining two conductive bolts 2 and the adapter circuit board 10. The control circuit board 15 infers the concentration of the gas based on the detected weak current and the linear relationship between the concentration of the measured gas and the current.

[0056] It can be understood that controlling the air pump 30 to work continuously can greatly reduce the accumulation of high-concentration gas.

[0057] It should be noted that the inference of the gas concentration based on the detected weak current and the linear relationship between the measured gas concentration and the current is well known to those skilled in the art and is not the focus of the present technology. Therefore, it will not be elaborated here. For details, please refer to the calculation process of the existing photoionization detector.

[0058] Example 2

[0059] This embodiment provides a portable photoionization gas detector, such as Figure 3 As shown, it includes: a shell 23, and a photoionization gas sensor, a whole machine mainboard and an air pump 30 arranged in the shell 23, and the photoionization gas sensor is the aforementioned photoionization gas sensor; wherein, the air inlet of the photoionization gas sensor is located outside the shell 23, serving as the air inlet of the photoionization gas detector.

[0060] In a specific embodiment, the upper end cover 1 of the photoionization gas sensor may be located entirely outside the housing 23 , and the housing sleeve 22 of the photoionization gas sensor may be located inside the housing 23 .

[0061] An exhaust port is disposed at the end of the housing 23 away from the air inlet, and the exhaust port is connected to the air outlet of the photoionization gas sensor through the air guide pipe 19 and the air pump 30 .

[0062] The air pump 30 and the control circuit boards of the photoionization gas sensor are electrically connected to the main board of the whole machine respectively.

[0063] In a specific implementation, the control circuit board of the photoionization gas sensor is electrically connected to the main board of the whole machine through a PCB terminal board.

[0064] Preferably, the air pump is a self-priming air pump.

[0065] In another embodiment, the portable photoionization gas detector also includes a water trap filter 24, which is connected to the air inlet and is used to filter large particles of dust and other impurities in the gas and absorb water vapor to ensure the purity of the gas entering the photoionization gas sensor and reduce the deposition of large particles of dust, other impurities and water vapor on the devices in the ionization chamber 28, which affects the accuracy of the gas concentration measurement results.

[0066] Furthermore, the portable photoionization gas detector also includes an air pump driving circuit 31 , which is electrically connected to the mainboard of the whole device and is used to drive the air pump 30 to work.

[0067] Preferably, Figure 4As shown, the air pump driving circuit 31 includes an NPN transistor Q14, a PMOS tube Q13, a freewheeling diode D20 and a sampling resistor R83. The PMOS tube Q13 is connected in series with the air pump 30 and is grounded through the sampling resistor R83; the intermediate connection point between the sampling resistor R83 and the air pump 30 is also connected to the control circuit board 15 through a resistor R79 to provide a sampling voltage to the control circuit board 15; the freewheeling diode D20 is reversely connected in parallel with the air pump 30, the collector of the NPN transistor Q14 is connected to the gate of the PMOS tube Q13, and is connected to the same power supply V_PUMP, and the emitter of the NPN transistor Q14 is grounded; the base of the NPN transistor Q14 is used to receive the control signal of the whole machine mainboard.

[0068] When in use, the control signal of the whole machine mainboard changes the potential of the gate of the PMOS tube Q13 by controlling the potential of the base of the NPN transistor Q14, thereby controlling the closing and conducting of the PMOS tube Q13; specifically, when the base of the NPN transistor Q14 is at a high level, the NPN transistor is turned on, and the potential of the gate of the PMOS tube Q13 changes from the power supply to the ground. At this time, the PMOS tube Q13 is turned on, and the air pump 30 starts to work, and the sampling voltage is input to the control circuit board 15 from the upper end of the sampling resistor R38 to monitor the working state of the air pump 30; when the base of the NPN transistor Q14 changes from a high potential to a low potential, the potential of the gate of the PMOS tube Q13 changes from a low potential to a high potential, and the PMOS tube Q13 is turned off. At this time, the air pump 30 can discharge the induced electromotive force through the freewheeling diode D20 to avoid damage to the air pump 30.

[0069] Correspondingly, pulse width modulation can also be performed through the whole machine mainboard to control the frequency and switching time of the base switch of the NPN transistor Q14, change the output effective voltage, and then change the air flow rate of the air pump 30.

[0070] In this embodiment, the flow rate of the gas pump 30 is controlled between 200 and 500 ml / min, which ensures that the sampled gas can undergo normal ionization reaction without causing excessive reaction or incomplete detection.

[0071] In order to alert the staff when the detected gas concentration exceeds a preset value, the portable photo-ionization gas detector also includes a composite alarm module 32 electrically connected to the whole machine mainboard, and the composite alarm module 32 includes a buzzer 26, a multi-color LED lamp 27 and a vibration motor, wherein the multi-color LED lamp 26 is arranged on the whole machine mainboard, the buzzer 26 and the vibration motor are arranged in the detector body, and a light-transmitting hole is arranged on the outer shell 23 corresponding to the multi-color LED lamp 26.

[0072] Furthermore, a screen display 25 is also provided on the main board of the whole machine. The screen display 25 is electrically connected to the control circuit board 15 of the photoionization gas sensor and is used to display the working status of the detector and the real-time concentration value of the detected gas. A screen mounting hole is provided on the housing 23 corresponding to the screen display 25.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the utility model can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the utility model, which should be included in the scope of the technical solution for protection of the utility model.

Claims

1. A photoionization gas sensor, characterized in that: It comprises a sensor housing, an ionization chamber, an ultraviolet lamp, an ultraviolet lamp control board and a control circuit board, wherein an air inlet and an air outlet are respectively arranged at two ends of the sensor housing, and the ionization chamber, the ultraviolet lamp, the ultraviolet lamp control board and the control circuit board are arranged in the sensor housing; The ionization chamber comprises an upper gas chamber cover, an electrode circuit board and a lower gas chamber cover, wherein two collecting electrodes are arranged in parallel on the electrode circuit board; four bolt holes are arranged on the upper gas chamber cover and the lower gas chamber cover respectively, and four conductive holes are arranged on the electrode circuit board corresponding to the conductive bolts, wherein two conductive holes are electrically connected to the two collecting electrodes respectively; an irradiation window is arranged at the center of the lower gas chamber cover; An air inlet hole is arranged on the upper part of the upper air chamber cover corresponding to the air inlet, and the air inlet hole is communicated with the air inlet; a vent hole is arranged on the electrode circuit board corresponding to the air inlet hole, and an air outlet hole is arranged on the lower part of the lower air chamber cover symmetrically with the center of the air inlet hole, and the air outlet is communicated with the air outlet hole; A transfer circuit board is fixedly connected to the side of the lower air chamber cover facing away from the upper air chamber cover, and four conductive connecting pieces corresponding to the conductive bolts are arranged on the transfer circuit board I, and an irradiation through hole is also arranged on the transfer circuit board corresponding to the irradiation window; The ultraviolet lamp is arranged in the ultraviolet lamp cover corresponding to the irradiation window, and a high-voltage excitation electrode for applying high voltage to the ultraviolet lamp is also arranged inside the ultraviolet lamp cover, and the end of the ultraviolet lamp cover close to the lower air chamber cover is provided with mounting holes corresponding to four conductive connectors; the upper air chamber cover, the electrode circuit board, the lower air chamber cover, the adapter circuit board and the ultraviolet lamp cover are fixedly connected by conductive bolts, bolt holes, conductive holes and mounting holes to form a closed cavity; The ultraviolet lamp control board is arranged on one side of the ultraviolet lamp cover, and the ultraviolet lamp control board is electrically connected to the high-voltage excitation electrode; The control circuit board is arranged on the other side of the ultraviolet lamp cover, and the control circuit board is electrically connected to four conductive connectors and the ultraviolet lamp control board through FPC flexible flat cables; two conductive bolts are also connected to two collecting electrodes through the conductive holes.

2. A photoionization gas sensor according to claim 1, characterized in that: The conductive connecting member is a conductive sleeve, and the conductive bolt is fixed in the conductive sleeve after passing through the bolt hole of the upper air chamber cover, the conductive hole of the electrode circuit board and the bolt hole of the lower air chamber cover.

3. A photoionization gas sensor according to claim 2, characterized in that: The conductive bolt is connected to the conductive sleeve by threaded fixing or plug-in fixing.

4. A portable photoionization gas detector, characterized in that: include: A housing, and a photoionization gas sensor, a mainboard and an air pump arranged in the housing, wherein the photoionization gas sensor is the photoionization gas sensor according to any one of claims 1 to 3; wherein an air inlet of the photoionization gas sensor is located outside the housing, serving as an air inlet of the photoionization gas detector; An exhaust port is provided at the end of the housing away from the air inlet, and the exhaust port is connected to the air outlet of the photoionization gas sensor through an air guide pipe and the air pump; The control circuit boards of the air pump and the photoionization gas sensor are respectively connected to the main board of the whole machine.

5. A portable photoionization gas detector according to claim 4, characterized in that: It also includes an air pump driving circuit, which is electrically connected to the whole machine mainboard and is used to drive the air pump to work.

6. A portable photoionization gas detector according to claim 5, characterized in that: The air pump driving circuit includes an NPN transistor, a PMOS transistor, a freewheeling diode and a sampling resistor. The PMOS transistor is connected in series with the air pump and is grounded through the sampling resistor; the freewheeling diode is connected in parallel with the air pump and is reversely connected. The collector of the NPN transistor is connected to the gate of the PMOS transistor and is connected to the same power supply. The emitter of the NPN transistor is grounded, and the base of the NPN transistor is used to receive the control signal of the whole machine mainboard.

7. A portable photoionization gas detector according to any one of claims 4 to 6, characterized in that: It also includes a composite alarm module electrically connected to the mainboard of the whole machine, and the composite alarm module includes a buzzer, a multi-color LED lamp and a vibration motor, wherein the multi-color LED is arranged on the mainboard of the whole machine, the buzzer and the vibration motor are arranged in the outer shell, and a light-transmitting hole is arranged on the outer shell corresponding to the multi-color LED lamp.

8. A portable photoionization gas detector according to claim 7, characterized in that: The portable photoionization gas detector further comprises a water trap filter, and the water trap filter is connected to the air inlet of the photoionization gas detector.

9. A portable photoionization gas detector according to claim 8, characterized in that: The whole machine mainboard is also provided with a screen display screen, the screen display screen is electrically connected to the control circuit board of the photoionization gas sensor, and the housing is provided with a screen mounting hole corresponding to the screen display screen.

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