A handheld laser dust particle counter

Abstract

The invention discloses a handheld laser dust particle counter, which belongs to the field of handheld laser dust particle counters. After the filter, sampling head and handheld laser dust particle counter are installed, the structural integration is stronger, which reduces the risk of losing the sampling head or filter during later use. At the same time, the integrated installation structure can realize the automatic one-time switching of air flow paths, calibration and detection functions without disassembling the filter and the sampling head through the coordinated work of the components inside the delayed air intake valve and the negative pressure valve shell, thereby greatly improving the convenience of use. At the same time, the delayed air intake valve can also keep clean air continuously sucked into the detection chamber of the handheld laser dust particle counter for a certain period of time, so that the dust particles remaining in the detection chamber during the previous detection are continuously sucked out by the negative pressure suction pump and discharged outside the detection chamber, so as to meet the calibration effect before formal detection.

Description

Technical Field

[0001] The invention relates to the field of handheld laser dust particle counters, and more particularly to a handheld laser dust particle counter. Background Art

[0002] In today's industries, the requirements for environmental cleanliness are becoming more and more stringent. In industries such as semiconductor manufacturing, biopharmaceuticals, and food processing, dust particles in the environment will seriously affect product quality and performance. Therefore, it is particularly necessary to use a handheld laser dust particle counter to detect the cleanliness of the environment and understand the environmental conditions in order to improve product quality and performance.

[0003] The basic principle of the handheld laser dust particle counter is to work based on the light scattering effect. When the dust particles in the air are sucked by the negative pressure pump inside the counter and the externally installed sampling head enters the detection chamber inside the counter, when the laser beam emitted by the laser generator installed inside the counter shines on the dust particles, these particles will cause the laser to scatter. The intensity and angle of the scattered light of dust particles of different particle sizes are different. Then the optical detector installed inside the counter can capture these scattered lights and then convert the optical signals into electrical signals. By analyzing and processing these electrical signals and using specific algorithms, the particle size of the dust particles and the number of particles of the corresponding particle size can be calculated, thereby realizing the measurement of the concentration and particle size distribution of dust particles in the air.

[0004] Although the existing handheld laser dust particle counters have many advantages in use, they are usually equipped with a sampling head and a filter in a split-installation form, which are plugged in and disassembled and used in conjunction with the air source interface end on the handheld laser dust particle counter. Therefore, the handheld laser dust particle counter needs to install the filter before using the sampling head for sampling, so that the outside air is filtered by the filter and enters the detection chamber in the form of clean airflow. The sampling head can be installed for formal sampling only after the dust particles remaining in the detection chamber are blown out and the calibration purpose is achieved. Therefore, the sampling head and the filter in the split-installation form not only need to frequently disassemble and assemble the sampling head and the filter when dealing with multi-frequency sampling, which is inconvenient to use, and the sampling head and the filter in the split-installation form also increase the risk of losing the sampling head or the filter.

[0005] Therefore, based on the above, a sampling head and filter are developed in an integrated installation. There is no need to disassemble and replace the sampling head and filter during calibration and formal sampling, and the air flow path corresponding to the sampling head and filter and the air source interface end can be automatically switched. This is particularly necessary to further improve the convenience and safety of using a handheld laser dust particle counter. Therefore, we propose a handheld laser dust particle counter to solve the above problems. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the problems existing in the prior art, the present invention aims to provide a handheld laser dust particle counter, which firstly installs the filter and the sampling head integrally with the air source interface end of the handheld laser dust particle counter through the delayed air inlet valve, the extension tube and the negative pressure valve housing, so that the filter, the sampling head and the handheld laser dust particle counter have a stronger structural integration after being installed, reduces the risk of the sampling head or the filter being lost during the later use, and improves the safety of use;

[0008] The delayed air inlet valve provided at the same time has the function of delaying the closing of the air flow passage inside the stroke section, so that after the pressing head is pressed to the bottom in the direction of the sealing cover before the initial use, the air flow passage of the hollow sleeve inside the stroke section is opened, and the air containing dust particles from the outside can first pass through the filter and be filtered by the filter layer, and enter the hollow sleeve inside the stroke section in the form of clean air flow, and then enter the handheld laser dust particle counter through the connecting cavity section, the exhaust nozzle and the air source interface end, and then enter the inside of its detection chamber, suck out the dust particles remaining in the detection chamber and discharge them to the outside of the detection chamber to achieve the purpose of calibration, and then the push rod inside the hollow sleeve is supported by the rebound force of the spring and the push rod The reverse pulling force and the friction force of a group of sealing rings and the conical plug cause the conical plug to slowly reset and block the inner concave hole of the metal contact piece. At this time, the delayed closing function of the airflow path inside the stroke section is completed. At the same time, a negative pressure state is formed inside the connecting cavity section and the negative pressure valve shell, forcing the circular floating piece to deviate to the side of the installation nozzle, opening the airflow path of the extension tube. At this time, the air containing dust particles in the outside world can be switched to the airflow path formed by the sampling head, the extension tube and the negative pressure valve shell, and directly enter the detection chamber of the counter to be irradiated by the laser for detection, thereby completing the one-time effect of automatically completing the airflow path switching, calibration and detection functions without disassembling the filter and the sampling head, which greatly improves the convenience of use;

[0009] By setting the delayed air intake valve and the components inside the negative pressure valve housing, the air flow path can be automatically switched. At the same time, the delayed air intake valve can also keep clean air continuously sucked into the detection chamber of the handheld laser dust particle counter for a certain period of time, so that the dust particles remaining in the detection chamber during the previous detection can be continuously sucked out by the negative pressure suction pump and discharged out of the detection chamber, so as to meet the calibration effect before the formal detection.

[0010] 2. Technical solution

[0011] To solve the above problems, the present invention adopts the following technical solutions.

[0012] A handheld laser dust particle counter, comprising a handheld laser dust particle counter, a filter, a sampling head and a delayed air intake valve, wherein the delayed air intake valve comprises a hollow shell, and the hollow shell comprises a stroke section and a connecting cavity section, the inner wall of the hollow shell between the stroke section and the connecting cavity section is fixedly connected to a limit ring seat, an air intake nozzle 1 is fixedly connected to the outer wall of the hollow shell located on the stroke section, and an air intake nozzle 2 and an exhaust nozzle are respectively fixedly connected to the outer wall of the hollow shell located on the connecting cavity section, and the air intake nozzle 1, the air intake nozzle 2 and the exhaust nozzle are all connected to the inside of the hollow shell;

[0013] The interior of the hollow shell located inside the stroke section is sleeved with a metal contact sheet, an annular sealing gasket and a hollow sleeve in sequence, one end of the hollow sleeve is fixedly connected with a sleeve edge, one side of the sleeve edge is in close contact with one side of the metal contact sheet through the annular sealing gasket, and the other side of the metal contact sheet is in close contact with one side of the limit ring seat, a plurality of through holes are equidistantly provided on the outer wall of the hollow sleeve, a sealing cover is fixedly installed at one end of the hollow shell, and one end of the hollow sleeve is in close contact with one side of the inner wall of the sealing cover;

[0014] A push rod is sleeved at the center position inside the hollow sleeve, and an extrusion sheet and a group of sleeve sheets are fixedly connected to the push rod located inside the stroke section, and a group of the sleeve sheets are fixedly sleeved with sealing rings on the outer edges, and the outer edges of a group of the sealing rings are in close contact with the inner wall of the hollow sleeve, and a conical plug is fixedly sleeved on the push rod located on one side of the extrusion sheet, and an inner concave hole matching the outer structure of the conical plug is opened inside the metal contact sheet, and the conical plug fits the inside of the inner concave hole;

[0015] One end of the push rod passes through the connecting cavity section to the outside of the hollow outer shell, and a pressing head is fixedly installed on one end of the push rod by a screw, and a supporting spring is sleeved on the outside of the push rod between the hollow outer shell and the pressing head, and two ends of the supporting spring are respectively in contact with one side of the pressing head and one side of the outer wall of the hollow outer shell, and a positioning seat is also fixedly connected to the inner wall of the hollow outer shell located inside the connecting cavity section, and the positioning seat is sleeved on the outside of the push rod through a sealing sleeve.

[0016] Furthermore, the bottom of the sampling head is fixedly connected to a negative pressure valve shell through an extension tube, and one end of the negative pressure valve shell is fixedly connected to a mounting nozzle, and the mounting nozzle is fixedly installed on the second air inlet nozzle, and a positioning plate is fixedly installed inside the negative pressure valve shell, a sliding hole is opened at the center position inside the positioning plate, and a connecting column is slidably connected inside the sliding hole, one end of the connecting column is fixedly connected to a circular floating piece, and an O-type rubber ring is fixedly sleeved on the outer side of the circular floating piece, and the outer side of the O-type rubber ring is in contact with the corresponding position of the negative pressure valve shell, and a reset spring is sleeved on the connecting column located between the positioning plate and the circular floating piece.

[0017] Furthermore, an inner concave straight groove is opened at the top of the inner wall of the hollow sleeve, the inner wall diameter of the inner concave hole is larger than the outer wall diameter of the push rod, the outer wall diameters of a group of the sealing ring outer edge and the outer wall diameters of the conical plug outer edge are equal to the inner wall diameter of the hollow sleeve, and a group of the sealing ring, the conical plug and the annular sealing gasket are all made of friction-resistant rubber material.

[0018] Furthermore, a concave sleeve groove is provided on one side of the pressing head at the connection point of the support spring and on one side of the outer wall of the hollow shell.

[0019] Furthermore, the filter includes an air inlet end, a filter element housing and an air outlet end, the filter element housing is filled with a filter layer, the air outlet end is fixedly installed on the air inlet nozzle, the handheld laser dust particle counter is fixedly connected to an air source interface end, and the exhaust nozzle is fixedly installed on the air source interface end.

[0020] 3. Beneficial effects

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] (1) In this solution, the filter and the sampling head are respectively installed integrally with the air source interface end of the handheld laser dust particle counter through the delayed air inlet valve, the extension tube and the negative pressure valve housing, so that the filter, the sampling head and the handheld laser dust particle counter have a stronger structural integration after installation, reducing the risk of the sampling head or the filter being lost during later use, thereby improving the safety of use;

[0023] (2) In this solution, the delayed air intake valve has the function of delaying the closing of the air flow path inside the stroke section, so that before the initial use, after the pressing head is pressed to the bottom in the direction of the sealing cover, the air flow path of the hollow sleeve inside the stroke section is opened, and the air containing dust particles from the outside can first pass through the filter and be filtered by the filter layer, and enter the hollow sleeve inside the stroke section in the form of clean air flow, and then enter the handheld laser dust particle counter through the connecting cavity section, the exhaust nozzle and the air source interface end, and then enter the detection chamber thereof, suck out the dust particles remaining inside the detection chamber and discharge them to the outside of the detection chamber to achieve the purpose of calibration, and then the push rod inside the hollow sleeve is supported by the rebound force of the spring. The reverse pulling force of the push rod and the friction force of a group of sealing rings and the conical plug cause the conical plug to slowly reset and block the inner concave hole of the metal contact piece. At this time, the delayed closing function of the air flow path inside the stroke section is completed. At the same time, a negative pressure state is formed inside the connecting cavity section and the negative pressure valve shell, forcing the circular floating piece to deviate to the side of the installation nozzle, opening the air flow path of the extension tube. At this time, the air containing dust particles in the outside world can be switched to the air flow path formed by the sampling head, the extension tube and the negative pressure valve shell, and directly enter the detection chamber of the counter to be irradiated by the laser for detection, thereby completing the one-time effect of automatically completing the air flow path switching, calibration and detection functions without disassembling the filter and the sampling head, which greatly improves the convenience of use;

[0024] (3) In this solution, the delayed air intake valve and the components inside the negative pressure valve housing can complete the automatic switching of the air flow path. At the same time, the delayed air intake valve can also allow clean air to be continuously sucked into the detection chamber of the handheld laser dust particle counter for a certain period of time, so that the dust particles remaining in the detection chamber during the previous detection are continuously sucked out by the negative pressure suction pump and discharged outside the detection chamber, thereby achieving the calibration effect before the formal detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 For the present invention Figure 1 A schematic diagram of the structure of the enlarged part of the middle area;

[0027] Figure 3 It is a schematic diagram of the split structure of the present invention;

[0028] Figure 4 It is a structural schematic diagram of the delayed air intake valve of the present invention;

[0029] Figure 5 It is a schematic cross-sectional structure diagram of the delayed intake valve of the present invention;

[0030] Figure 6 For the present invention Figure 5A schematic diagram of the structure of the enlarged part of the middle area;

[0031] Figure 7 It is a schematic diagram of the internal cross-sectional structure of the negative pressure valve housing of the present invention;

[0032] Figure 8 It is a schematic diagram of the top view of the positioning plate of the present invention.

[0033] Description of the numbers in the figure:

[0034] 1. Handheld laser dust particle counter; 101. Gas source interface;

[0035] 2. Filter; 201. Air inlet; 202. Filter housing; 203. Air outlet;

[0036] 3. Delayed air intake valve; 4. Hollow shell; 401. Stroke section; 402. Connecting cavity section; 4021. Positioning seat; 403. Limiting ring seat; 404. Inlet nozzle 1; 405. Inlet nozzle 2; 406. Exhaust nozzle; 5. Metal contact piece; 501. Inner concave hole; 6. Ring sealing gasket; 7. Hollow sleeve; 701. Socket edge; 702. Through hole; 703. Inner concave straight groove; 8. Sealing cover; 9. Push rod; 901. Extrusion piece; 902. Socket piece; 10. Sealing ring; 11. Conical plug; 12. Pressing head; 13. Support spring;

[0037] 14. Sampling head; 15. Extension tube; 16. Negative pressure valve housing; 1601. Mounting nozzle; 17. Positioning plate; 1701. Sliding hole; 18. Connecting column; 19. Circular floating sheet; 20. O-type rubber ring; 21. Reset spring. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the specification of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0039] Embodiment 1:

[0040] See also Figure 1-Figure 8A handheld laser dust particle counter comprises a handheld laser dust particle counter 1, a filter 2, a sampling head 14 and a delayed air intake valve 3, wherein the delayed air intake valve 3 comprises a hollow shell 4, and the hollow shell 4 comprises a stroke section 401 and a connecting cavity section 402, a limited position ring seat 403 is fixedly connected to the inner wall of the hollow shell 4 between the stroke section 401 and the connecting cavity section 402, an air intake nozzle 1 404 is fixedly connected to the outer wall of the hollow shell 4 located on the stroke section 401, and an air intake nozzle 2 405 and an exhaust nozzle 406 are respectively fixedly connected to the outer wall of the hollow shell 4 located on the connecting cavity section 402, and the air intake nozzle 1 404, the air intake nozzle 2 405 and the exhaust nozzle 406 are all connected to the inside of the hollow shell 4;

[0041] The hollow housing 4 located inside the stroke section 401 is sleeved with a metal contact sheet 5, an annular sealing gasket 6 and a hollow sleeve 7 in sequence. One end of the hollow sleeve 7 is fixedly connected with a sleeve edge 701. One side of the sleeve edge 701 is in close contact with one side of the metal contact sheet 5 through the annular sealing gasket 6. The other side of the metal contact sheet 5 is in close contact with one side of the limit ring seat 403. A plurality of through holes 702 are equidistantly provided on the outer wall of the hollow sleeve 7. A sealing cover 8 is fixedly installed at one end of the hollow housing 4. One end of the hollow sleeve 7 is in close contact with one side of the inner wall of the sealing cover 8.

[0042] A push rod 9 is sleeved at the center of the hollow sleeve 7. An extrusion sheet 901 and a set of sleeve pieces 902 are fixedly connected to the push rod 9 located inside the stroke section 401. A sealing ring 10 is fixedly sleeved on the outer edges of the set of sleeve pieces 902, and the outer edges of the set of sealing rings 10 are in close contact with the inner wall of the hollow sleeve 7. A conical plug 11 is fixedly sleeved on the push rod 9 located on one side of the extrusion sheet 901. An inner concave hole 501 matching the outer structure of the conical plug 11 is opened inside the metal contact sheet 5, and the conical plug 11 fits the inside of the inner concave hole 501.

[0043] One end of the push rod 9 passes through the connecting cavity section 402 to the outside of the hollow shell 4, and a pressing head 12 is fixedly installed on one end of the push rod 9 by a screw, and a support spring 13 is sleeved on the outside of the push rod 9 between the hollow shell 4 and the pressing head 12, and the two ends of the support spring 13 are respectively in contact with one side of the pressing head 12 and one side of the outer wall of the hollow shell 4, and a positioning seat 4021 is also fixedly connected to the inner wall of the hollow shell 4 inside the connecting cavity section 402, and the positioning seat 4021 is sleeved on the outside of the push rod 9 through a sealing sleeve;

[0044] The bottom of the sampling head 14 is fixedly connected to a negative pressure valve housing 16 through an extension tube 15, and one end of the negative pressure valve housing 16 is fixedly connected to a mounting nozzle 1601, and the mounting nozzle 1601 is fixedly installed on the air inlet nozzle 405. A positioning plate 17 is fixedly installed inside the negative pressure valve housing 16, and a sliding hole 1701 is opened at the center position inside the positioning plate 17, and a connecting column 18 is slidably connected inside the sliding hole 1701. A circular floating sheet 19 is fixedly connected to one end of the connecting column 18, and an O-type rubber ring 20 is fixedly sleeved on the outside of the circular floating sheet 19. The outside of the O-type rubber ring 20 contacts the corresponding position of the negative pressure valve housing 16, and a reset spring 21 is sleeved on the connecting column 18 between the positioning plate 17 and the circular floating sheet 19;

[0045] The filter 2 includes an air inlet end 201, a filter element housing 202 and an air outlet end 203. The filter element housing 202 is filled with a filter layer. The air outlet end 203 is fixedly installed on an air inlet nozzle 404. The handheld laser dust particle counter 1 is fixedly connected to an air source interface end 101, and an exhaust nozzle 406 is fixedly installed on the air source interface end 101.

[0046] The operating principle of this handheld laser dust particle counter is:

[0047] First, since the circular floating piece 19 inside the negative pressure valve housing 16 is supported by the return spring 21, the circular floating piece 19 is in close contact with the corresponding position of the negative pressure valve housing 16 through the O-type rubber ring 20, blocking the air flow path at the sampling head 14 and the extension tube 15;

[0048] Then, when the detection begins, the handheld laser dust particle counter 1 is first powered on to start the negative pressure suction pump and the laser emitter installed inside it. The negative pressure suction pump is used to suck the airflow into the detection chamber through the air source interface end 101, and then it is irradiated by the laser beam emitted by the laser emitter, and then the irradiated airflow is drawn to the outside of the detection chamber until it is discharged to the outside of the handheld laser dust particle counter 1 (the specific structure and detection principle inside the handheld laser dust particle counter are considered to be existing known public technologies, so they will not be described in detail here);

[0049] When the handheld laser dust particle counter 1 is powered on, the pressing head 12 is first pressed to the bottom in the direction of the sealing cover 8, so that the push rod 9 drives the conical plug 11, the extrusion sheet 901, a set of sleeve sheets 902 and a set of sealing rings 10 to move to one side of the sealing cover 8. At this time, the air flow path formed by the air inlet nozzle 404, the inside of the stroke section 401, the plurality of through holes 702, the inner concave hole 501 and the connecting cavity section 402 is opened, and the air containing dust particles from the outside first passes through the inside of the filter 2 and is filtered by the filter layer, and then enters the air inlet nozzle 404 in the form of clean air flow. Inside, the clean air flow passes through the inside of the stroke section 401, the several through holes 702 on the hollow sleeve 7, and the inner concave hole 501 on the metal contact sheet 5 in turn to enter the inside of the connecting cavity section 402, and then the clean air flow passes through the exhaust nozzle 406 to enter the inside of the air source interface end 101, and is sucked into the inside of the detection chamber by the negative pressure suction pump inside the handheld laser dust particle counter 1, and then is irradiated by the laser beam emitted by the laser transmitter, while the dust particles remaining in the previous detection inside the detection chamber are sucked out and discharged to the outside of the detection chamber to achieve the purpose of calibration before detection;

[0050] At the same time, the push rod 9 inside the hollow sleeve 7 is affected by the rebound force of the support spring 13, the reverse pulling force of the push rod 9, and the friction between a group of sealing rings 10 and the conical plug 11 and the inner wall of the hollow sleeve 7, so that the conical plug 11 is slowly pulled in the reverse direction to reset, and the inner concave hole 501 of the metal contact piece 5 is blocked, and the function of delayed closing of the air flow passage inside the stroke section 401 is completed, that is, the process of self-cleaning inside the detection chamber is completed;

[0051] At the same time, affected by the vacuum pumping operation, a negative pressure state is formed inside the communicating cavity section 402 and the negative pressure valve shell 16 connected by the second air inlet nozzle 405 and the mounting nozzle 1601, forcing the circular floating sheet 19 to deviate to the side of the mounting nozzle 1601. The circular floating sheet 19 is disengaged from the corresponding position of the negative pressure valve shell 16 through the O-type rubber ring 20, and the air flow path at the sampling head 14 and the extension tube 15 is opened. At this time, the air containing dust particles in the outside world can be switched to the air flow path formed by the sampling head 14, the extension tube 15 and the negative pressure valve shell 16 and directly enter the air source interface end 101 of the handheld laser dust particle counter 1, and then smoothly enter the detection chamber to be irradiated by the laser for detection (the specific structure and detection principle inside the handheld laser dust particle counter are considered to be existing known public technologies, so they will not be described in detail here), thereby completing the one-time effect of automatically completing the air flow path switching, calibration and detection functions without disassembling the filter 2 and the sampling head 14, thereby greatly improving the convenience of use.

[0052] Embodiment 2:

[0053] In view of the above embodiment 1, for further description, refer to Figure 6 A concave straight groove 703 is provided on the top of the inner wall of the hollow sleeve 7, the inner wall diameter of the concave hole 501 is larger than the outer wall diameter of the push rod 9, the outer wall diameters of the outer edges of a set of sealing rings 10 and the outer edges of the conical plug 11 are equal to the inner wall diameter of the hollow sleeve 7, a set of sealing rings 10, the conical plug 11 and the annular sealing gasket 6 are all made of friction-resistant rubber material; a concave sleeve groove is provided on one side of the pressing head 12 at the connection of the support spring 13 and on one side of the outer wall of the hollow shell 4.

[0054] A pressure relief channel can be formed by the recessed straight groove 703, so as to avoid the conical plug 11 and the sealing ring 10 being unable to smoothly complete the reciprocating movement process due to the conical plug 11 and the sealing ring 10 being too tightly fitted to the inner wall of the hollow sleeve 7 and the air flow being unable to flow; the setting of the conical plug 11 can not only seal the concave hole 501 to achieve the effect of opening and closing the air flow passage, but also can be used in combination with a group of sealing rings 10 to move close to the inner wall of the hollow sleeve 7, thereby increasing the friction force received by the conical plug 11 when moving, thereby achieving the effect of slowly resetting the conical plug 11 and delaying the sealing of the concave hole 501.

[0055] The above is only a preferred specific implementation of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved conception within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A handheld laser dust particle counter, comprising a handheld laser dust particle counter (1), a filter (2), a sampling head (14) and a delayed air intake valve (3), characterized in that: The delayed air intake valve (3) comprises a hollow shell (4), and the hollow shell (4) comprises a stroke section (401) and a connecting cavity section (402); a limit ring seat (403) is fixedly connected to the inner wall of the hollow shell (4) between the stroke section (401) and the connecting cavity section (402); an air intake nozzle 1 (404) is fixedly connected to the outer wall of the hollow shell (4) on the stroke section (401); an air intake nozzle 2 (405) and an exhaust nozzle (406) are respectively fixedly connected to the outer wall of the hollow shell (4) on the connecting cavity section (402); the air intake nozzle 1 (404), the air intake nozzle 2 (405) and the exhaust nozzle (406) are all connected to the interior of the hollow shell (4); The hollow shell (4) located inside the travel section (401) is sleeved with a metal contact sheet (5), an annular sealing gasket (6) and a hollow sleeve (7) in sequence, one end of the hollow sleeve (7) is fixedly connected with a sleeve edge (701), one side of the sleeve edge (701) is in close contact with one side of the metal contact sheet (5) through the annular sealing gasket (6), and the other side of the metal contact sheet (5) is in close contact with one side of the limit ring seat (403), a plurality of through holes (702) are equidistantly provided on the outer wall of the hollow sleeve (7), one end of the hollow shell (4) is fixedly installed with a sealing cover (8), and one end of the hollow sleeve (7) is in close contact with one side of the inner wall of the sealing cover (8); A push rod (9) is sleeved at the center position inside the hollow sleeve (7), and an extrusion sheet (901) and a group of sleeve sheets (902) are fixedly connected to the push rod (9) located inside the stroke section (401), and a sealing ring (10) is fixedly sleeved on the outer edges of a group of sleeve sheets (902), and the outer edges of a group of sealing rings (10) are in close contact with the inner wall of the hollow sleeve (7), and a conical plug (11) is fixedly sleeved on the push rod (9) located on one side of the extrusion sheet (901), and an inner concave hole (501) adapted to the outer structure of the conical plug (11) is opened inside the metal contact sheet (5), and the conical plug (11) fits the inside of the inner concave hole (501); One end of the push rod (9) passes through the connecting cavity section (402) to the outside of the hollow shell (4), and a pressing head (12) is fixedly installed on one end of the push rod (9) by means of screws. A support spring (13) is sleeved on the outside of the push rod (9) located between the hollow shell (4) and the pressing head (12), and two ends of the support spring (13) are respectively in contact with one side of the pressing head (12) and one side of the outer wall of the hollow shell (4). A positioning seat (4021) is also fixedly connected to the inner wall of the hollow shell (4) located inside the connecting cavity section (402), and the positioning seat (4021) is sleeved on the outside of the push rod (9) through a sealing sleeve.

2. A handheld laser dust particle counter according to claim 1, characterized in that: The bottom of the sampling head (14) is fixedly connected to a negative pressure valve housing (16) through an extension tube (15), and one end of the negative pressure valve housing (16) is fixedly connected to a mounting nozzle (1601), and the mounting nozzle (1601) is fixedly installed on the second air inlet nozzle (405). A positioning plate (17) is fixedly installed inside the negative pressure valve housing (16), and a sliding hole (1701) is opened at the center position inside the positioning plate (17), and a connecting column (18) is slidably connected inside the sliding hole (1701). One end of the connecting column (18) is fixedly connected to a circular floating sheet (19), and an O-type rubber ring (20) is fixedly sleeved on the outer side of the circular floating sheet (19), and the outer side of the O-type rubber ring (20) contacts the corresponding position of the negative pressure valve housing (16), and a reset spring (21) is sleeved on the connecting column (18) located between the positioning plate (17) and the circular floating sheet (19).

3. The handheld laser dust particle counter according to claim 1, characterized in that: A concave straight groove (703) is provided at the top of the inner wall of the hollow sleeve (7); the inner wall diameter of the concave hole (501) is larger than the outer wall diameter of the push rod (9); the outer wall diameters of the outer edges of a set of sealing rings (10) and the outer edges of the conical plug (11) are equal to the inner wall diameter of the hollow sleeve (7); and the sealing rings (10), the conical plug (11) and the annular sealing gasket (6) are all made of friction-resistant rubber material.

4. The handheld laser dust particle counter according to claim 1, characterized in that: A concave sleeve groove is provided on one side of the pressing head (12) and one side of the outer wall of the hollow outer shell (4) at the connection point of the supporting spring (13).

5. The handheld laser dust particle counter according to claim 1 is characterized in that: The filter (2) comprises an air inlet end (201), a filter element housing (202) and an air outlet end (203); the filter element housing (202) is filled with a filter layer; the air outlet end (203) is fixedly mounted on the air inlet nozzle (404); the handheld laser dust particle counter (1) is fixedly connected to an air source interface end (101); and the exhaust nozzle (406) is fixedly mounted on the air source interface end (101).

Images