A toxic gas detector

Abstract

The present invention discloses a toxic gas detector, which relates to the technical field of toxic gas detection. A negative pressure fan blade and auxiliary blades are arranged in the detection cylinder of the present invention to form a negative pressure flow field. The bottom of the cylinder is adaptively accelerated by a gear ring-planetary control mechanism. The separation dust box adopts a tangential multi-channel air intake and is equipped with an inverted conical sliding funnel to separate particles by centrifugation. The purified gas is sent to the electrochemical sensor group through a coaxial central air intake pipe to achieve highly sensitive monitoring of hydrogen sulfide, carbon monoxide, oxygen, and ammonia. The present invention solves the problems of easy dust clogging, insufficient flow, and cumbersome maintenance of existing detectors, improves detection speed, accuracy, and reliability, and is suitable for continuous safety monitoring in various high-risk environments such as mines, chemical industries, and municipal pipelines.

Description

Technical Field

[0001] The present invention relates to the technical field of poisonous gas detection, in particular to a poisonous gas detector. Background Art

[0002] Existing portable or fixed multi-gas detectors usually use a single-stage dust filter in conjunction with a micro vacuum pump to push external air directly into the electrochemical sensor cavity. Due to the lack of an effective centrifugal separation mechanism in the air path, dust and water mist in the air can easily deposit on the sensor surface, shortening the life of the component and causing sensitivity drift. On the other hand, the micro pump and the fan have a fixed transmission ratio, and the speed is constrained by the rated limit of the motor. It is difficult to provide sufficient air intake in complex scenarios such as high concentration, low oxygen or high humidity, resulting in prolonged response time or even false alarms. Traditional structures rely on regular replacement of external filter elements, but frequent disassembly and assembly increase maintenance costs. Summary of the Invention

[0003] In order to overcome the defects of the above-mentioned prior art, the present invention provides the following technical solutions: a toxic gas detector, comprising a detection tube, a meter head is fixedly installed on the detection tube by installing an air guide seat, and an outer shell of the meter head is provided with an exhaust hole connected to the inside of the detection tube; a separation dust box is fixedly and sealedly installed on the end of the detection tube away from the air guide seat in a manner that is easy to disassemble, and a plurality of air inlet channels are provided on the circumferential surface of the separation dust box along its own tangential direction; a drive motor is fixedly installed on the top of the inner wall of the detection tube through a plurality of drive motor brackets, four of which are respectively fixedly installed with four electrochemical gas sensors, each electrochemical gas sensor to detect a different type of gas, and the four electrochemical gas sensors are used to detect hydrogen sulfide, carbon monoxide, oxygen and ammonia respectively; a negative pressure fan blade is rotatably provided at the bottom of the inner wall of the detection tube, and the negative pressure fan blade is used to drive external air to flow to all electrochemical gas sensors; wherein the negative pressure fan blade is connected to the output shaft of the drive motor through the control part.

[0004] Preferably, a central air inlet pipe is provided at the axial position of the separation dust box, a central air inlet port is provided on the circumferential surface of the central air inlet pipe, a sliding funnel is fixedly provided at the middle of the inner wall of the separation dust box, the center position of the sliding funnel is lower than the edge position, so that the sliding funnel is set in an inverted cone shape; a partition plate is fixedly installed at the top of the inner wall of the separation dust box, and the partition plate is slidably sleeved on the circumferential surface of the central air inlet pipe.

[0005] Preferably, the negative pressure fan blades are composed of multiple blades, and auxiliary blades are fixedly installed between two adjacent blades through auxiliary blade brackets. All auxiliary blades and blades on the negative pressure fan blades are used to drive air flow.

[0006] Preferably, the rotation center position of the negative pressure fan blade is mounted on the negative pressure fan blade driving spline shaft in a spline sliding manner, and the bottom end of the negative pressure fan blade driving spline shaft is rotatably mounted on a stable bracket, and the stable bracket is fixedly mounted on the bottom end of the inner wall of the detection cylinder.

[0007] Preferably, the regulating part includes a gear ring disk, and a regulating drive gear is rotatably provided at the center position of the inner side of the gear ring disk. The regulating drive gear and the gear ring disk are meshed and transmitted through a regulating ring gear. The regulating ring gear is rotatably installed on the regulating disk, and the regulating disk and the gear ring disk are coaxially arranged; the gear ring disk and the regulating disk are rotatably arranged between the opposite surfaces of the top bracket plate and the middle bracket plate, wherein the top bracket plate and the middle bracket plate are fixedly installed on the inner wall of the detection cylinder; wherein the gear ring disk is fixedly matched with the output shaft of the drive motor.

[0008] Preferably, a regulating and limiting sleeve is rotatably installed at the center position of the intermediate bracket plate, and the regulating and limiting sleeve is coaxially fixedly matched with the regulating disk, and a limiting engagement disk is coaxially provided inside the regulating and limiting sleeve (the limiting engagement disk is rotationally and slidingly matched with the inner wall of the negative pressure fan blade pull tube or has no connection relationship); a rotating engagement disk is fixedly installed on the end of the regulating and limiting sleeve away from the regulating disk, and teeth that can engage with each other are provided between the opposite surfaces of the rotating engagement disk and the limiting engagement disk.

[0009] Preferably, a polished rod shaft is fixedly installed at the axial position of the regulating drive gear, and a negative pressure fan blade driving spline shaft is coaxially fixedly installed on the polished rod shaft, and a sliding sleeve on the circumferential surface of the polished rod shaft is provided with a limiting meshing disk supporting spline rod, and one end of the limiting meshing disk supporting spline rod is fixedly matched with the limiting meshing disk, wherein the limiting meshing disk supporting spline rod is installed on the bottom bracket plate in a spline sliding manner, and the bottom bracket plate is fixedly installed on the inner wall of the detection cylinder, wherein the regulating limiting sleeve is rotationally matched with the bottom bracket plate.

[0010] Preferably, a reset spring is provided around the outer side of the limiting meshing disk supporting spline rod, one end of the reset spring is respectively fixed to the bottom bracket plate, and the other end of the reset spring is fixed to the end of the limiting meshing disk supporting spline rod away from the limiting meshing disk; wherein the end of the limiting meshing disk supporting spline rod away from the limiting meshing disk is also rotatably installed with a negative pressure fan blade pull tube, the negative pressure fan blade pull tube sleeve is arranged on the outer side of the negative pressure fan blade driving spline shaft, and the other end of the negative pressure fan blade pull tube is fixedly matched with the negative pressure fan blade, wherein the negative pressure fan blade pull tube and the limiting meshing disk supporting spline rod can only rotate circumferentially and cannot axially move relative to each other.

[0011] Preferably, a conical partition is fixedly mounted on the first end of the detection cylinder away from the air guide seat, and the conical partition is fixedly connected to the central air inlet pipe.

[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention forms a high-efficiency centrifugal field by separating the tangential multi-channel air intake of the dust collecting box and the internal inverted conical sliding funnel. The particulate impurities are thrown to the inner wall under the action of the rotating airflow and gravity and finally deposited at the bottom of the funnel, preventing them from entering the central air intake pipe and the detection cylinder; compared with the single-layer filter element solution, the frequency of sensor surface contamination and the wear rate of the fan blades can be significantly reduced, and the long-term zero point stability can be maintained. At the same time, the operation and maintenance work of frequent filter element replacement is eliminated, and the reliability of the whole machine and the continuous online monitoring capability are improved; (2) The present invention uses an adaptive transmission mechanism composed of a gear ring disk, a regulating surrounding gear and a regulating drive gear. The system can automatically lock the planetary revolution and convert it into a high-transmission ratio direct drive mode, so that the fan blades are instantly increased to an extreme value higher than the rated speed of the motor. In complex or sudden leakage scenarios, the air intake volume can be quickly increased, the sensor response time can be shortened, and the detection sensitivity of low ppm-level toxic gases can be improved, thereby gaining precious seconds-level warning for personnel safety; (3) The main negative pressure fan blades of the present invention cooperate with the control part to realize flow field guidance, thereby ensuring the stability of the overall negative pressure inside the cylinder, ensuring that each electrochemical gas sensor obtains the same amount and speed of gas at different spatial orientations, and improving the repeatability and accuracy of multi-component detection; (4) The conical partition of the present invention adopts a coaxial connection layout with the central air intake pipe, so that the dust-free and purified gas is quickly introduced into the sensor area along a straight channel, and the backflow generated by the separation chamber is effectively blocked by the cone surface, avoiding the secondary vortex from bringing particles back into the gas path. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the header structure of the present invention.

[0014] Figure 2 This is a structural diagram of the air guide seat installed in the present invention.

[0015] Figure 3 This is a structural diagram of the separation dust box of the present invention.

[0016] Figure 4 This is a schematic diagram of the internal structure of the detection tube of the present invention.

[0017] Figure 5 This is a structural diagram of the auxiliary blade of the present invention.

[0018] Figure 6 It is a structural schematic diagram of the support plate of the present invention.

[0019] Figure 7 For the present invention Figure 6 Schematic diagram of the structure at point A in the middle.

[0020] Figure 8 Schematic diagram of the structure of the control unit of the present invention.

[0021] In the figure: 101-header; 102-gas guide seat; 103-detection cylinder; 104-separation dust box; 105-air inlet channel; 106-partition plate; 107-conical partition; 108-center air inlet pipe; 109-center air inlet port; 110-drive motor; 111-sliding funnel; 112-drive motor bracket; 113-electrochemical gas sensor; 114-top bracket plate; 115-middle bracket plate; 116-bottom bracket plate; 117- Stabilizing bracket; 118-reset tension spring; 119-negative pressure fan blade; 120-negative pressure fan blade drive spline shaft; 121-auxiliary blade; 122-auxiliary blade bracket; 123-negative pressure fan blade pull tube; 124-gear ring disk; 125-regulating disk; 126-regulating surround gear; 127-regulating drive gear; 128-limiting meshing disk; 129-rotating meshing disk; 130-limiting meshing disk supporting spline rod; 131-light rod shaft; 132-regulating limiting sleeve. DETAILED DESCRIPTION

[0022] The following is combined with Figures 1-8 , and further illustrate the technical solution of the present invention through specific implementation methods.

[0023] The present invention provides a toxic gas detector, comprising a detection tube 103, on which a meter head 101 is fixedly installed by installing a gas guide seat 102, and an outer shell of the meter head 101 is provided with an exhaust hole communicated with the interior of the detection tube 103; a separation dust box 104 is fixedly and sealedly installed at one end of the detection tube 103 away from the gas guide seat 102 in a manner that is easy to disassemble, and a plurality of air inlet channels 105 are provided on the circumferential surface of the separation dust box 104 along its own tangential direction; a drive motor 110 is fixedly installed on the top of the inner wall of the detection tube 103 by means of a plurality of drive motor brackets 112, and four electrochemical gas sensors 113 are fixedly installed on four of the drive motor brackets 112, and each electrochemical gas sensor 113 is used to detect a different type of gas, wherein the four electrochemical gas sensors 113 are used to respectively detect hydrogen sulfide (for example, using an electrochemical sensor with model H2S-A1), carbon monoxide (for example, using an electrochemical sensor with model CO-H4 / The detection tube 103 is provided with a negative pressure fan 119 at the bottom of the inner wall thereof, which is used to drive external air to all electrochemical gas sensors 113. The negative pressure fan 119 is connected to the output shaft of the drive motor 110 via a control unit. The separation dust collection box 104 is provided with a central air inlet pipe 108 at the axial center thereof, and a central air inlet port 109 is provided on the circumferential surface thereof. A sliding funnel 111 is fixedly provided at the middle of the inner wall of the separation dust collection box 104. The center position of the sliding funnel 111 is lower than the edge position, so that the sliding funnel 111 is arranged in an inverted cone shape. A partition plate 106 is fixedly installed at the top of the inner wall of the separation dust collection box 104, and the partition plate 106 is slidably sleeved on the circumferential surface of the central air inlet pipe 108. The negative pressure fan blades 119 are composed of multiple blades, with auxiliary blades 121 mounted overhead and fixed between adjacent blades via auxiliary blade brackets 122. All auxiliary blades 121 and the blades on the negative pressure fan blades 119 are used to drive air flow. The rotation center of the negative pressure fan blades 119 is splined and slidingly mounted on the negative pressure fan blade drive spline shaft 120. The bottom end of the negative pressure fan blade drive spline shaft 120 is rotatably mounted on a stable bracket 117, which is fixedly mounted on the bottom end of the inner wall of the detection cylinder 103.

[0024] The regulating part includes a gear ring disk 124, and a regulating drive gear 127 is rotatably provided at the center position of the inner side of the gear ring disk 124. The regulating drive gear 127 and the gear ring disk 124 are meshed and transmitted through a regulating surround gear 126. The regulating surround gear 126 is rotatably mounted on the regulating disk 125, and the regulating disk 125 and the gear ring disk 124 are coaxially arranged; the gear ring disk 124 and the regulating disk 125 are rotatably arranged between the opposite surfaces of the top bracket plate 114 and the middle bracket plate 115, wherein the top bracket plate 114 and the middle bracket plate 115 are fixedly mounted on the inner wall of the detection cylinder 103; wherein the gear ring disk 124 is fixedly matched with the output shaft of the drive motor 110. A regulating and limiting sleeve 132 is rotatably installed at the center position of the intermediate bracket plate 115, and the regulating and limiting sleeve 132 is coaxially fixedly matched with the regulating disk 125. A limiting engagement disk 128 is coaxially provided inside the regulating and limiting sleeve 132 (the limiting engagement disk 128 is rotationally and slidingly matched with the inner wall of the negative pressure fan blade pull tube 123 or has no connection relationship); a rotating engagement disk 129 is fixedly installed at the end of the regulating and limiting sleeve 132 away from the regulating disk 125, and teeth that can engage with each other are provided between the opposite surfaces of the rotating engagement disk 129 and the limiting engagement disk 128. The axial position of the regulating drive gear 127 is fixedly installed with a polished rod shaft 131, and the negative pressure fan blade driving spline shaft 120 is coaxially fixedly installed on the polished rod shaft 131. The circumferential surface sliding sleeve of the polished rod shaft 131 is provided with a limiting meshing disk supporting spline rod 130, and one end of the limiting meshing disk supporting spline rod 130 is fixedly matched with the limiting meshing disk 128, wherein the limiting meshing disk supporting spline rod 130 is installed on the bottom bracket plate 116 in a spline sliding manner, and the bottom bracket plate 116 is fixedly installed on the inner wall of the detection cylinder 103, wherein the regulating limiting sleeve 132 is rotationally matched with the bottom bracket plate 116. A return spring 118 is provided around the outer side of the limit meshing disk support spline rod 130. One end of the return spring 118 is fixed to the bottom bracket plate 116, and the other end of the return spring 118 is fixed to the end of the limit meshing disk support spline rod 130 away from the limit meshing disk 128. The end of the limit meshing disk support spline rod 130 away from the limit meshing disk 128 is also rotatably mounted with a negative pressure fan blade pull tube 123. The negative pressure fan blade pull tube 123 is sleeved on the outer side of the negative pressure fan blade drive spline shaft 120. The other end of the negative pressure fan blade pull tube 123 is fixedly engaged with the negative pressure fan blade 119. The negative pressure fan blade pull tube 123 and the limit meshing disk support spline rod 130 can only rotate circumferentially and cannot move relative to each other axially. A conical partition 107 is fixedly mounted on the first end of the detection cylinder 103 away from the air guide seat 102. The conical partition 107 is fixedly connected to the central air inlet pipe 108.

[0025] The working principle of the toxic gas detector disclosed in the present invention is as follows: a meter head 101 is installed in the toxic gas environment to be detected, and is fixed with screws through a plurality of lugs provided on the outer shell of the meter head 101. During detection, the drive motor 110 is started, and the output shaft of the drive motor 110 drives the gear ring disk 124 to rotate. The gear ring disk 124 drives the regulating ring gear 126 and the regulating drive gear 127 to rotate through the transmission friction force. In this process, the regulating disk 125 will also rotate. The rotation of the regulating drive gear 127 will drive the light rod shaft 131 and the negative pressure fan blade driving spline shaft 120 to rotate together (the rotation axis of the negative pressure fan blade driving spline shaft 120 and the light rod shaft 131 is coaxial). The negative pressure fan blade driving spline shaft 120 drives the negative pressure fan blades 119 and the auxiliary blades 121 to rotate, and then the air under the negative pressure fan blades 119 is discharged to the top. At this time, the space under the negative pressure fan blades 119, that is, the air pressure inside the conical partition 107, the central air inlet pipe 108, and the separation dust box 104 will be reduced, which will cause the external gas to enter the separation dust box 104 through the air inlet channel 105 along the tangent of the inner wall of the separation dust box 104. At this time, the gas entering the separation dust box 104 will rotate inside the separation dust box 104. If the inhaled gas contains particulate impurities, these impurities will follow the rotation and rotate along the inner wall of the separation dust box 104 under the action of centrifugal force (and gradually move toward the surface of the sliding funnel 111 under the action of gravity. When the detection is stopped, that is, when the drive motor 110 is not working, these particulate impurities will slide to the bottom of the separation dust box 104 and be restricted by the sliding funnel 111 to prevent overflowing to the outside of the separation dust box 104. The separation dust box 104 needs to be regularly cleaned. The interior is cleaned), and the relatively pure gas is sucked into the central air inlet pipe 108 through the central air inlet 109, and then enters the detection cylinder 103, and is discharged to the electrochemical gas sensor 113 by the negative pressure fan blades 119 and the auxiliary blades 121. The threshold values ​​of hydrogen sulfide, carbon monoxide, oxygen and ammonia are detected by different types of electrochemical gas sensors 113. When the concentration exceeds the standard, an alarm is issued and displayed on the display screen of the header 101 (the header 101 integrates an alarm, a relay controller (linked to external devices such as the wind brake motor), and a display screen).

[0026] If the detection sensitivity is improved, the output shaft of the drive motor 110 can be directly controlled to accelerate so that the speed of the drive motor 110 reaches the rated maximum speed. During the acceleration process, the speed of the negative pressure fan blades 119 and the auxiliary blades 121 will gradually increase. However, when the speed of the negative pressure fan blades 119 and the auxiliary blades 121 reaches a certain value, the air resistance of the negative pressure fan blades 119 and the auxiliary blades 121 will cause the speed of the auxiliary blades 121 and the negative pressure fan blades 119 to be unable to continue to increase. At this time, the extra power of the output shaft of the drive motor 110 is The force will be released by regulating the orbiting gear 126 and the regulating disk 125 to revolve around the axis of the light rod shaft 131 (it should be noted that the above movement is a process). When the negative pressure fan blade 119 and the auxiliary blade 121 increase to the maximum speed, the negative pressure fan blade pull tube 123 will be pulled to move, and the negative pressure fan blade pull tube 123 will pull the reset spring 118, so that the reset spring 118 is stretched (when stopped, it plays a role in resetting), and the negative pressure fan blade pull tube 123 will pull the limiting meshing disk support spline rod 130, limiting the meshing disk support The spline rod 130 pulls the limiting meshing disc 128 toward the rotating meshing disc 129. Since the limiting meshing disc supports the spline rod 130 and the limiting meshing disc 128 cannot rotate, when the limiting meshing disc 128 and the rotating meshing disc 129 are in contact and meshed, the rotating meshing disc 129 cannot rotate. The inability of the rotating meshing disc 129 to rotate will cause the regulating limiting sleeve 132 and the regulating disc 125 to be unable to rotate, that is, the regulating surrounding gear 126 cannot revolve around the axis of the light rod shaft 131. At this time, the output of the drive motor 110 The output shaft power will be completely transmitted to the control drive gear 127 through the gear ring disk 124 and the control ring gear 126, and the transmission ratio of this process is acceleration. At this time, the rotation speed of the control drive gear 127, the polished rod shaft 131, and the negative pressure fan blade drive spline shaft 120 reaches the maximum, so the rotation speed of the negative pressure fan blade 119 and the auxiliary blade 121 is the maximum. At the same time, the pulling force on the negative pressure fan blade pull tube 123 is also the maximum, that is, the limiting engagement disk 128 and the rotating engagement disk 129 will always maintain a contact and engagement state (and mainly be subjected to tangential force). At this time, more gas can be allowed to enter the detection cylinder 103, so that more gas contacts the electrochemical gas sensor 113, increasing the sensitivity of the detection. In other words, if the drive motor 110 is used to directly drive the negative pressure fan blade 119 to rotate, when the rotation speed of the negative pressure fan blade 119 reaches the rated maximum speed of the output shaft of the drive motor 110, the speed cannot be further increased. The control unit automatically increases the transmission ratio between the output shaft of the drive motor 110 and the negative pressure fan 119, thereby automatically increasing the speed of the negative pressure fan 119 and, in turn, increasing the air intake. This improves the detection sensitivity of the electrochemical gas sensor 113. Gas entering the detection cylinder 103 is ultimately discharged through the exhaust port of the meter head 101.

Claims

1. A toxic gas detector, characterized in that: The detection tube (103) comprises a meter head (101) fixedly connected to the detection tube (103) by installing an air guide seat (102), and an exhaust hole communicating with the interior of the detection tube (103) is provided on the outer shell of the meter head (101); a separation dust collection box (104) is fixedly and sealedly installed on the end of the detection tube (103) away from the air guide seat (102) in a manner that is easy to disassemble, and a plurality of air inlet channels (105) are opened on the circumferential surface of the separation dust collection box (104) along its own tangential direction; A driving motor (110) is fixedly mounted on the top of the inner wall of the detection cylinder (103) via a plurality of driving motor brackets (112), and four electrochemical gas sensors (113) are fixedly mounted on four of the driving motor brackets (112). Each electrochemical gas sensor (113) is configured to detect a different type of gas, and the four electrochemical gas sensors (113) are configured to detect hydrogen sulfide, carbon monoxide, oxygen, and ammonia, respectively. The bottom of the inner wall of the detection cylinder (103) is rotatably provided with a negative pressure fan blade (119), which is used to drive external air to flow toward all electrochemical gas sensors (113); wherein the negative pressure fan blade (119) is connected to the output shaft of the drive motor (110) through a control unit; The regulating portion comprises a toothed ring disk (124), a regulating drive gear (127) is rotatably provided at the center position inside the toothed ring disk (124), the regulating drive gear (127) and the toothed ring disk (124) are meshed and transmitted via a regulating surrounding gear (126), the regulating surrounding gear (126) is rotatably mounted on the regulating disk (125), and the regulating disk (125) and the toothed ring disk (124) are coaxially arranged; the toothed ring disk (124) and the regulating disk (125) are rotatably arranged between opposite surfaces of a top support plate (114) and an intermediate support plate (115), wherein the top support plate (114) and the intermediate support plate (115) are fixedly mounted on the inner wall of the detection cylinder (103); wherein the toothed ring disk (124) is fixedly matched with the output shaft of the drive motor (110).

2. A toxic gas detector according to claim 1, characterized in that: A central air inlet pipe (108) is provided at the axis position of the separation dust collecting box (104), a central air inlet port (109) is provided on the circumferential surface of the central air inlet pipe (108), a sliding funnel (111) is fixedly provided at the middle of the inner wall of the separation dust collecting box (104), the central position of the sliding funnel (111) is lower than the edge position, so that the sliding funnel (111) is arranged in an inverted cone shape; a partition plate (106) is fixedly installed at the top of the inner wall of the separation dust collecting box (104), and the partition plate (106) is slidably sleeved on the circumferential surface of the central air inlet pipe (108).

3. A toxic gas detector according to claim 2, characterized in that: The negative pressure fan blade (119) is composed of a plurality of blades, and an auxiliary blade (121) is fixedly mounted between two adjacent blades via an auxiliary blade bracket (122). All the auxiliary blades (121) and the blades on the negative pressure fan blade (119) are used to drive air flow.

4. A toxic gas detector according to claim 3, characterized in that: The rotation center position of the negative pressure fan blade (119) is mounted on the negative pressure fan blade drive spline shaft (120) in a spline sliding manner, and the bottom end of the negative pressure fan blade drive spline shaft (120) is rotatably mounted on the stable bracket (117), and the stable bracket (117) is fixedly mounted on the bottom end of the inner wall of the detection cylinder (103).

5. A toxic gas detector according to claim 4, characterized in that: A regulating and limiting sleeve (132) is rotatably mounted at the center of the intermediate bracket plate (115). The regulating and limiting sleeve (132) is coaxially fixedly matched with the regulating disk (125). A limiting engagement disk (128) is coaxially arranged inside the regulating and limiting sleeve (132). A rotating engagement disk (129) is fixedly mounted on one end of the regulating and limiting sleeve (132) away from the regulating disk (125). Teeth that can engage with each other are provided between opposing surfaces of the rotating engagement disk (129) and the limiting engagement disk (128).

6. A toxic gas detector according to claim 5, characterized in that: A polished rod shaft (131) is fixedly mounted on the axis of the regulating drive gear (127), and a negative pressure fan blade driving spline shaft (120) is coaxially fixedly mounted on the polished rod shaft (131). A sliding sleeve on the circumferential surface of the polished rod shaft (131) is provided with a limiting meshing disk supporting spline rod (130), one end of which is fixedly matched with the limiting meshing disk (128), wherein the limiting meshing disk supporting spline rod (130) is mounted on the bottom bracket plate (116) in a spline sliding manner, and the bottom bracket plate (116) is fixedly mounted on the inner wall of the detection cylinder (103), wherein the regulating limiting sleeve (132) is rotationally matched with the bottom bracket plate (116).

7. A toxic gas detector according to claim 6, characterized in that: A return spring (118) is provided around the outer side of the limiting meshing disk supporting spline rod (130), one end of the return spring (118) is fixed to the bottom bracket plate (116), and the other end of the return spring (118) is fixed to the end of the limiting meshing disk supporting spline rod (130) away from the limiting meshing disk (128); wherein the end of the limiting meshing disk supporting spline rod (130) away from the limiting meshing disk (128) is also rotatably mounted with a negative pressure fan blade pull tube (123), the negative pressure fan blade pull tube (123) is sleeved on the outer side of the negative pressure fan blade driving spline shaft (120), and the other end of the negative pressure fan blade pull tube (123) is fixedly matched with the negative pressure fan blade (119), wherein the negative pressure fan blade pull tube (123) and the limiting meshing disk supporting spline rod (130) can only rotate circumferentially and cannot move relative to each other axially.

8. A toxic gas detector according to claim 7, characterized in that: A conical partition (107) is fixedly mounted on the first end of the detection cylinder (103) away from the air guide seat (102), and the conical partition (107) is fixedly connected to the central air inlet pipe (108).

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