A gas buffer device for an individual sampler

Abstract

This invention discloses a gas buffer device for an individual sampler, comprising a buffer chamber, one chamber wall of which is an elastic diaphragm. The buffer chamber has an air inlet and an air outlet, with an air inlet pipe connector installed at the air inlet. An adjustment mechanism for adjusting the cross-sectional area of ​​the air outlet is installed inside the buffer chamber. This gas buffer device can convert the pulsating airflow generated by the diaphragm pump into a constant airflow and can also detect system leaks, preventing system leaks.

Description

Technical Field

[0001] This invention relates to the field of gas monitoring and sampling technology, and in particular to a gas buffer device for an individual sampler. Background Technology

[0002] A personal sampler is a portable instrument used to detect the air quality around the wearer. It is used to sample and detect harmful gases or particulate matter in the environment and air. Personal samplers are specialized sampling devices that can operate for extended periods, are compact and lightweight, easy to operate, convenient to use, and have stable performance. The patent document with patent number 202123450826.2 discloses a specific structure of an individual sampler. In general use, the sampler's air inlet is connected to a harmful gas absorption bottle or a particulate matter absorption filter membrane device via a pipe. The harmful gas absorption bottle or particulate matter absorption filter membrane device can be clipped to the operator's collar. In this way, the individual sampler can provide gas sampling power. The gas enters from near the operator's mouth and nose through the harmful gas absorption bottle or particulate matter absorption filter membrane device, then passes through the sampler and is discharged. The harmful gas is absorbed by the corresponding absorbent material in the absorption bottle, or the particulate matter is filtered by the filter membrane. Finally, the amount of harmful gas absorbed in the absorption bottle or the particulate matter in the filter membrane can be measured to obtain the amount of the target substance. Finally, the concentration of the harmful gas or particulate matter can be obtained by dividing the amount of harmful gas or particulate matter by the gas flow rate sampled by the individual sampler. Therefore, the accuracy of the sampler's gas flow rate directly determines the accuracy of the particulate matter or harmful gas concentration.

[0003] The sampling flow rate requirements for detecting hazardous gases and particulate matter differ. Gas flow rate is typically measured using an orifice plate flow meter, usually located downstream of the sampling pump in the individual sampler. The system's gas flow rate is obtained through pressure differential. A smaller sampling flow rate is needed for hazardous gas sampling, while a larger sampling flow rate is required for particulate matter detection. Currently, individual samplers use miniature diaphragm pumps for sampling power. However, the flow range of these diaphragm pumps is fixed, and the flow rate can only be adjusted by changing the motor speed. This method only allows for adjustment within a narrow range. Existing individual samplers' miniature diaphragm pumps are connected to a constant flow buffer chamber via a medium channel, the size of which cannot be changed. This results in small pressure differentials and insensitive pressure changes during low-flow operations. During high-flow operations, the medium velocity is high, the resistance increases exponentially, and power consumption is high. Furthermore, current individual samplers lack leak detection capabilities. If a leak occurs in the system, it may lead to inaccurate sampling flow rate, which in turn leads to inaccurate detection results.

[0004] To address the aforementioned technical problems, patent publication number 202011055615.6 discloses a miniature diaphragm pump with a precision flow regulating device. This diaphragm pump adds a flow regulating device to the original pump body. The flow regulating device has a very complex structure, including a regulating motor, a speed regulating component, and a regulating mechanism. The regulating mechanism includes a bushing and a shaft core. The bushing has a circular groove inside, into which gas output from the mixing chamber can be injected. The shaft core can enter the circular groove and has multiple holes penetrating the outer wall of the bushing and the circular groove. The regulating mechanism adjusts the number of holes through which gas flows in or out by varying the depth of the shaft core's entry into the circular groove. While this structure can solve the aforementioned technical problems, this solution still has significant technical shortcomings:

[0005] First, in the patent document 202011055615.6, the structure of the regulating device is very complex, the transmission between the regulating device and the regulating motor is also very complex, and the structure of the rotating inner shaft, telescopic shaft, and bushing is very complex. Furthermore, since the diaphragm pump itself is a micro pump, the overall size of these components is relatively small, and the overall component is very difficult to process, and the processing cost is also very high.

[0006] Secondly, the patent document uses a flow regulating device to fix the diaphragm pump to itself, which increases the length and size of the diaphragm pump assembly as a whole, and thus increases the size and weight of the individual sampler.

[0007] Furthermore, in this scheme, since the diaphragm pump and the flow regulating device are connected as one unit, generally speaking, once the diaphragm pump is damaged, the flow regulating device also needs to be replaced. This makes maintenance and replacement difficult and very costly. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a gas buffer device for an individual sampler, which can convert the pulsating airflow generated by the diaphragm pump into a constant airflow and at the same time detect the system for leaks, thereby preventing the occurrence of system leaks.

[0009] To solve the above-mentioned technical problems, the technical solution of the present invention is: a gas buffer device for an individual sampler, comprising a buffer chamber, one of the chamber walls of the buffer chamber being an elastic diaphragm, an air inlet and an air outlet being provided on the buffer chamber, an air inlet pipe connector being installed at the air inlet, and an adjustment mechanism for adjusting the cross-sectional area of ​​the air outlet being installed inside the buffer chamber.

[0010] As a preferred embodiment, the adjustment mechanism includes a sealing element that is slidably or rotatably installed in the buffer chamber, and the sealing element is driven by a linear power device or a rotary power device to move and adjust between the opening position and the closing position.

[0011] As a preferred embodiment, the buffer chamber is further provided with a normally open air port. Both the normally open air port and the chamber outlet are connected to the air outlet channel. The air outlet channel is used to connect to the air outlet pipe connector. The sealing element is sealed to the corresponding chamber outlet. The buffer chamber is provided with a detection port for detecting the internal pressure of the buffer chamber.

[0012] As a preferred embodiment, the sealing component includes a rotating disk, which is rotatably installed in the buffer chamber. The rotating disk is sealed to the chamber wall where the air outlet of the chamber is located. The rotating disk is provided with a plurality of vent holes of different diameters. The rotating power device drives the rotating disk to rotate so that one of the vent holes corresponds to the position of the air outlet, or the rotating disk blocks the air outlet of the chamber.

[0013] As a preferred embodiment, the sealing component includes a sealing rod, which is axially slidably installed in the buffer chamber. The end of the sealing rod is sealed to the air outlet of the chamber. The linear power device is installed in the buffer chamber and is in transmission engagement with the sealing rod.

[0014] As a preferred embodiment, the linear power device includes a geared motor, the output shaft of which is fixed with a drive gear, the sealing rod is fixed with a driven gear that meshes with the drive gear, the buffer chamber is fixed with a threaded sleeve, the sealing rod is threadedly installed in the threaded sleeve, and the drive gear drives the driven gear to rotate, thereby causing the sealing rod to move axially in a spiral manner.

[0015] As a preferred embodiment, a gas guide sleeve is fixed on the buffer chamber, the gas outlet of the gas guide sleeve is connected to the gas outlet of the chamber, the sealing element includes a piston rod and a piston installed at the end of the piston rod, the piston is axially and slidably installed in the gas guide sleeve, the piston divides the gas guide sleeve into a gas outlet chamber and an adjustment chamber, the side wall of the gas guide sleeve is provided with a plurality of axially extending air inlets, the air inlets connect the gas outlet chamber with the inner cavity of the buffer chamber, and the piston rod is driven by the linear power device.

[0016] As a preferred embodiment, the buffer chamber is externally fixed with an outer sleeve, and a piston sleeve is fixed inside the outer sleeve. A communicating cavity is provided between the piston sleeve and the outer sleeve. The sealing component includes a piston rod and a piston installed at the end of the piston rod. The piston is axially and slidably installed inside the piston sleeve. The piston divides the piston sleeve into an outlet chamber and an adjustment chamber. The side wall of the piston sleeve is provided with several axially distributed adjustment holes, which connect the piston sleeve to the communicating cavity. The outlet chamber is connected to the outlet of the buffer chamber. An outlet is provided on the outer sleeve. The piston rod is driven by the linear power device.

[0017] As a preferred embodiment, a guide block is detachably fixed to the outside of the buffer chamber. The position of the guide block corresponds to the position of the chamber's air outlet and normally open air port. The air outlet channel is provided on the guide block. The guide block is provided with a branch channel connecting the chamber's air outlet and normally open air port to the air outlet channel. A perforated plate corresponding to the chamber's air outlet and normally open air port is detachably installed between the guide block and the buffer chamber. Each perforated plate is located between the corresponding branch channel and the chamber's air outlet, and between the branch channel and the normally open air port.

[0018] As a preferred embodiment, the number of elastic diaphragms is two, and the two opposite chamber walls of the buffer chamber are provided with mounting slots. The elastic diaphragms are placed in the mounting slots and can be detachably fixed by pressure rings.

[0019] After adopting the above technical solution, the effect of the present invention is as follows: A gas buffer device for an individual sampler includes a buffer chamber, one chamber wall of which is an elastic diaphragm. The buffer chamber is provided with an air inlet and an air outlet. An air inlet pipe connector is installed at the air inlet. An adjustment mechanism for adjusting the cross-sectional area of ​​the air outlet is installed inside the buffer chamber. Therefore, the adjustment mechanism of this gas buffer device is located inside the buffer chamber, without increasing the overall size of the buffer chamber. Thus, this gas buffer device has the following advantages: 1. The elastic diaphragm of the buffer chamber can expand when the internal air pressure is high and contract when the internal air pressure is low, thereby ensuring a stable airflow rate from the buffer chamber and eliminating the pulsating airflow characteristics of the diaphragm pump in the individual sampler; 2. The adjustment mechanism is located inside the buffer chamber, without increasing the overall size of the buffer chamber. Therefore, for individual samplers… The overall size of the individual sampler is not affected. Furthermore, since the adjustment mechanism can adjust the cross-sectional area of ​​the chamber outlet, the ventilation resistance can be adjusted. When detecting harmful gases, a low flow rate is required. The diaphragm pump of the individual sampler will operate at a lower speed to control the sampling flow rate. At this time, the adjustment mechanism reduces the cross-sectional area of ​​the chamber outlet. The individual sampler can still maintain a certain ventilation resistance even at low flow rates. Therefore, to ensure the specified flow rate is reached, the diaphragm pump needs to increase its speed to achieve the rated sampling flow rate due to the smaller outlet cross-sectional area. This avoids unstable pump speed or insufficient starting torque at low flow rates. When detecting particulate matter, a high flow rate is required, the cross-sectional area of ​​the chamber outlet can be increased. This provides a sufficiently large outlet area to avoid excessive sampling gas resistance and prevents the diaphragm pump from rotating too fast, thus meeting the sampling requirements of different flow rates and making the individual sampler as small as possible.

[0020] Furthermore, since the buffer chamber is also equipped with a normally open vent, and both the normally open vent and the chamber outlet are connected to the outlet channel, which is used to connect to the outlet pipe connector, the sealing element is sealed to the corresponding chamber outlet. The buffer chamber is equipped with a detection port for detecting the internal pressure of the buffer chamber. Therefore, by sealing or not sealing the chamber outlet, the total outlet cross-sectional area can be changed. This allows for accurate adjustment of the sampling flow rate of the individual sampler. When detecting harmful gases, a small flow rate is required. In this case, the isolation pump of the individual sampler will operate at a lower speed to control the sampling flow rate. At this time, the chamber outlet can be sealed while the normally open vent remains open. Since only one normally open vent is open at this time, the outlet... With a relatively small cross-section, the individual sampler can maintain a certain differential pressure even at low flow rates. This not only facilitates accurate flow detection by the orifice plate flowmeter, but also ensures that the diaphragm pump can reach the specified flow rate by increasing its rotation speed to increase the sampling flow rate. This avoids the situation where the diaphragm pump's rotation speed is unstable or fails to start at low flow rates. When a large flow rate is required for particulate matter detection, the chamber outlet can be opened, providing a sufficiently large outlet area to prevent the sampled gas flow rate from being too fast at high flow rates. This also prevents the diaphragm pump from exceeding its rated speed. At the same time, the entire structure is located in the buffer chamber, requiring no additional space, thus meeting the sampling requirements of different flow rates and making the size of the individual sampler as small as possible.

[0021] Furthermore, since the sealing component includes a rotating disk, which is rotatably installed in the buffer chamber, the rotating disk is sealed to the chamber wall where the chamber outlet is located. The rotating disk is provided with several vent holes of different diameters. The rotating power device drives the rotating disk to rotate so that one of the vent holes corresponds to the position of the outlet hole, or the rotating disk blocks the chamber outlet. The rotating disk can be driven to rotate by the rotating power device, so that the vent holes of different diameters on the rotating disk correspond to the chamber outlet, thereby changing the size of the overall outlet cross section and adjusting the sampling flow rate. Of course, if it is necessary to block the chamber outlet, it is only necessary to seal the solid plate surface of the rotating disk with the chamber outlet to block the chamber outlet and complete the leak detection.

[0022] Furthermore, since the sealing component includes a sealing rod, which is axially slidably installed within the buffer chamber, and its end is sealed to the chamber's outlet, the linear power device is installed within the buffer chamber and engages with the sealing rod in a transmission manner. The linear power device includes a geared motor, the output shaft of which is fixed with a drive gear. A driven gear meshing with the drive gear is fixed on the sealing rod. A threaded sleeve is fixed on the buffer chamber, and the sealing rod is threadedly installed within the sleeve. The drive gear drives the driven gear to rotate, causing the sealing rod to move axially in a spiral motion. Therefore, the sealing rod, driven axially by the geared motor to block the chamber's outlet, can also achieve the blocking or opening of the outlet, thereby regulating the flow rate. Simultaneously, the driving structure of this sealing rod is simple, and the geared motor can drive the sealing rod stably in the open or closed position, making the structure more reliable.

[0023] Furthermore, since a gas guide sleeve is fixed on the buffer chamber, and the outlet end of the gas guide sleeve is connected to the outlet of the chamber, the sealing component includes a piston rod and a piston installed at the end of the piston rod. The piston is axially and slidably installed inside the gas guide sleeve, and the piston divides the gas guide sleeve into an outlet chamber and an adjustment chamber. The side wall of the gas guide sleeve is provided with several axially extending air inlets, which connect the outlet chamber to the inner cavity of the buffer chamber. The piston rod is driven by the linear power device. Therefore, by using the linear power device to drive the axial movement of the piston rod, the piston rod drives the piston to move axially, thereby changing the size of the outlet chamber, and thus changing the number of air inlets corresponding to the outlet chamber, thereby changing the cross-sectional area of ​​the connection between the buffer chamber and the outlet chamber, which also realizes the adjustment of the flow rate and meets the requirements of different sampling conditions.

[0024] Furthermore, since the buffer chamber is detachably fixed with an air guide block, the position of the air guide block corresponds to the position of the chamber's air outlet and normally open air outlet. The air outlet channel is set on the air guide block, and the air guide block is provided with a branch channel connecting the chamber's air outlet and normally open air outlet to the air outlet channel. A perforated plate corresponding to the chamber's air outlet and normally open air outlet is detachably installed between the air guide block and the buffer chamber. Each perforated plate is located between the corresponding branch channel and the chamber's air outlet, and between the branch channel and the normally open air outlet. Using this air guide block, the perforated plate can be better set and installed, and the branch channels can be easily set up and the air outlets of each chamber can be connected. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Figure 1 This is a three-dimensional structural diagram of Embodiment 1 of the present invention;

[0027] Figure 2 yes Figure 1A 3D image hidden behind the elastic diaphragm is shown in the image.

[0028] Figure 3 It is a 3D view from another angle, hiding the elastic diaphragm;

[0029] Figure 4 This is a top view of Embodiment 1;

[0030] Figure 5 yes Figure 4 Sectional view at AA;

[0031] Figure 6 yes Figure 4 Sectional view at BB;

[0032] Figure 7 This is a structural schematic diagram of Example 2;

[0033] Figure 8 This is a schematic diagram of the rotating disk in Example 2;

[0034] Figure 9 This is a schematic diagram of the structure of Example 3;

[0035] Figure 10 This is a structural schematic diagram of Example 4;

[0036] In the attached diagram: 1. Buffer chamber; 11. Normally open air port; 12. Chamber outlet; 13. Mounting countersunk outlet; 2. Air guide block; 21. Branch channel; 22. Air outlet channel; 23. Air outlet hole; 24. Large-diameter orifice plate; 25. Small-diameter orifice plate; 3. Pressure ring; 4. Elastic diaphragm; 5. Adjusting mechanism; 51. Linear power unit; 52. Driven gear; 53. Sealing rod; 54. Screw sleeve; 55. Drive gear; 56. Rotary disk; 561. Vent hole; 57. Rotary power unit; 58. Air guide sleeve; 59. Piston rod; 510. Piston; 511. Air outlet chamber; 512. Air inlet; 513. Internal threaded geared motor; 514. Adjusting air hole; 515. Outer sleeve; 516. Connecting cavity; 517. Piston cavity sleeve; 6. Inner cavity; 7. Detection pipe connector; 8. Air inlet pipe connector. Detailed Implementation

[0037] The present invention will be further described in detail below through specific embodiments.

[0038] Example 1

[0039] like Figures 1 to 6As shown, a gas buffer device for a personal sampler is disclosed. This personal sampler is used by an individual to sample the air around the user, thereby detecting whether the ambient air particulate matter or harmful gases meet the standards. The personal sampler generally includes a housing, inside which a sampling pump, a buffer chamber 1, a battery, an orifice plate flow meter, and some connecting pipes are typically installed. Specifically, a particulate matter filter (membrane device) or a harmful gas absorption bottle is threaded onto the air inlet of the personal sampler housing. The air inlet is connected to the air inlet of the sampling pump. The air outlet 12 of the sampling pump is connected to the air inlet of the buffer chamber 1. The air outlet 12 of the buffer chamber 1 is connected to the orifice plate flow meter, and finally, the gas is discharged. The sampling pump provides power for sampling, and the battery provides power to the sampling pump. The purpose of the buffer chamber 1 is to convert the pulsed airflow of the sampling pump into a constant airflow to ensure the accuracy of airflow detection. The orifice plate flow meter reflects the gas flow rate by detecting the differential pressure on both sides of the orifice plate.

[0040] In this embodiment, the gas buffer device includes a buffer chamber 1, one of the chamber walls of which is an elastic diaphragm 4. The buffer chamber 1 has an inner cavity 6. The elastic diaphragm 4 can expand when the internal air pressure of the buffer chamber 1 is high and contract when the internal air pressure is low, thereby ensuring a stable airflow rate from the buffer chamber 1 and eliminating the pulsating airflow characteristics of the diaphragm pump. In this embodiment, there are two elastic diaphragms 4. The two opposite chamber walls of the buffer chamber 1 are provided with mounting countersunk holes 13. The elastic diaphragms 4 are placed in the mounting countersunk holes 13 and are detachably fixed by bolts using pressure rings 3.

[0041] The buffer chamber 1 is provided with an air inlet and a chamber air outlet 12. An air inlet pipe connector 8 is installed at the air inlet, and the chamber air outlet 12 connects the buffer chamber 1 to the external environment. An adjustment mechanism 5 is fixed inside the buffer chamber 1 to close or open the chamber air outlet 12.

[0042] The adjustment mechanism 5 includes a sealing element that is slidably or rotatably installed in the buffer chamber 1. The sealing element is driven by a linear power device 51 or a rotary power device 57 to move and adjust between the open position and the close position. In this embodiment, the opening or closing of the chamber outlet 12 is realized by the adjustment mechanism 5. When it is open, it can meet the normal gas flow requirements of the gas sampler, and when it is closed, it can detect whether there is a leak in the pipeline system.

[0043] In this embodiment, more preferably, the buffer chamber 1 is further provided with a normally open vent 11. Both the normally open vent 11 and the chamber outlet 12 are connected to the outlet channel 22. The outlet pipe connector is connected to the outlet channel 22. The sealing member is sealed to the corresponding chamber outlet 12. The buffer chamber 1 is provided with a detection port for detecting the internal pressure of the buffer chamber 1. A detection pipe connector 7 for easy connection to pipelines is installed at the detection port. In the above structure, the normally open vent 11 and the chamber outlet 12 can actually form an orifice plate throttling structure. Therefore, the pressure difference between the inside and outside of the buffer chamber 1 can be detected by a differential pressure sensor, thereby detecting the outlet flow rate of the buffer chamber 1.

[0044] In this embodiment, the diameter of the normally open air port 11 is smaller than the diameter of the chamber outlet 12. The sealing component includes a sealing rod 53, which is axially slidably installed in the buffer chamber 1. The end of the sealing rod 53 is sealed to the chamber outlet 12. The linear power device 51 is installed in the buffer chamber 1 and is driven by the sealing rod 53. In this embodiment, there is one chamber outlet 12 and one normally open air port 11. Of course, there can also be two chamber outlets 12 with different diameters, and two sets of sealing rods 53 are provided. Each set of sealing rods 53 is driven by a corresponding linear power device 51, which can form more combinations. Combination 1: Normally open air inlet 11 is open, and both chamber outlets 12 are closed; Combination 2: Normally open air inlet 11 is open, the small-diameter chamber outlet 12 is open, and the large-diameter chamber outlet 12 is closed; Combination 3: Normally open air inlet 11 is open, the small-diameter chamber outlet 12 is closed, and the large-diameter chamber outlet 12 is open; Combination 4: Normally open air inlet 11 is open, and both chamber outlets 12 are open.

[0045] In this embodiment, the linear power device 51 includes a geared motor, the output shaft of which is fixed with a drive gear 55. The sealing rod 53 is fixed with a driven gear 52 that meshes with the drive gear 55. The buffer chamber 1 is fixed with a threaded sleeve 54. The sealing rod 53 is threadedly installed in the threaded sleeve 54. The drive gear 55 drives the driven gear 52 to rotate, and the rotation of the driven gear 52 will drive the sealing rod 53 to move axially in a spiral direction, thereby completing the sealing or opening of the air outlet 12 of the chamber.

[0046] like Figure 2 and Figure 5As shown, a gas guide block 2 is detachably fixed to the outside of the buffer chamber 1. The position of the gas guide block 2 corresponds to the positions of the chamber's air outlet 12 and normally open air outlet 11. The air outlet channel 22 is provided on the gas guide block 2, and one end of the air outlet channel 22 is sealed by a sealing screw. The gas guide block 2 is provided with an air outlet hole 23 that communicates with the air outlet channel 22 to facilitate gas discharge. The gas guide block 2 is provided with a branch channel 21 that connects the chamber's air outlet 12 and normally open air outlet 11 to the air outlet channel 22. The gas guide block 2 and the buffer chamber 1 are detachably connected. The system is equipped with orifice plates corresponding one-to-one with the chamber outlet 12 and the normally open air port 11. Each orifice plate is located between the corresponding branch channel 21 and the chamber outlet 12, and between the branch channel 21 and the normally open air port 11. In this embodiment, there are two orifice plates: a small-diameter orifice plate 25 is installed between the normally open air port 11 and the branch channel, while a large-diameter orifice plate 24 is installed between the chamber outlet 12 and the branch channel. The orifice plates can be clamped and fixed by both the air guide block 2 and the buffer chamber 1, or they can be threaded and fixed at the chamber outlet 12. By changing the orifice plates with different orifice diameters, the size of the air outlet cross-section can be changed, making adjustment very convenient.

[0047] Currently, the outlet cross-sectional area of ​​the conventional buffer chamber outlet 12 in existing individual samplers is not adjustable. Therefore, this outlet 12 cannot meet the requirements of very low or very high flow rates. In other words, the current isolation sampler has a relatively narrow range. This is because when the outlet cross-sectional area of ​​the chamber outlet 12 is fixed, the flow rate can only be adjusted by controlling the speed of the diaphragm pump within a certain range. For example, when the flow rate requirement is very low, the speed of the diaphragm pump will decrease. A very low speed of the diaphragm pump will lead to the following problems: 1. The speed of the diaphragm pump may be too low to start; 2. The low speed of the diaphragm pump will cause large fluctuations in airflow, affecting the stability of airflow; 3. The low speed of the diaphragm pump will result in overall... The flow rate is relatively low, and the pressure difference between the buffer chamber and the external pressure is relatively small. This results in low differential pressure detection accuracy and inaccurate detection results for the orifice plate flowmeter. Therefore, in order to adapt to the sampling and detection of harmful gases, individual samplers can only set the orifice diameter of the chamber outlet to be relatively small at the factory. However, a small chamber outlet diameter cannot meet the sampling requirements of large flow rates. When large flow rate sampling is required, a larger flow velocity is needed due to the small diameter of the chamber outlet. Consequently, the resistance at the outlet end of the diaphragm pump is also very large, requiring an increase in rotational speed to increase the flow velocity. This may cause the diaphragm pump to exceed its rated speed, leading to damage to the diaphragm pump. Therefore, the current isolation samplers have a small measurement range.

[0048] In this embodiment, the gas buffer device is installed after the individual sampler. When harmful gas sampling and detection are required, a small flow rate is needed. The normally open gas port 11 is opened while the chamber outlet 12 is closed. At this time, since the cross-sectional area of ​​the channel flowing out of the buffer chamber 1 becomes smaller, the flow rate needs to be increased in order to achieve the set flow rate. At this time, the diaphragm pump needs to increase its speed. This can prevent the speed from approaching or falling below the starting speed of the diaphragm pump during small flow sampling, thus avoiding the phenomenon of the diaphragm pump stopping or becoming unstable due to excessively low speed. In addition, since only the normally open gas port 11 is opened during small flow sampling, the diameter is small, so the pressure difference will be relatively large. Therefore, the orifice plate flow meter has higher accuracy when detecting pressure difference, and the detection results are more accurate.

[0049] When particulate matter sampling and detection is required, the detection flow rate of particulate matter is generally large, sometimes reaching 10 times that of harmful gas sampling flow rate. In this case, the outlet 12 of the chamber can be opened, which increases the total outlet cross-sectional area. This allows the diaphragm pump to meet the large flow rate requirement for particulate matter sampling by appropriately increasing its speed. Therefore, the diaphragm pump will also operate at a safe speed, ensuring the sampling continuity and reliability of the individual sampler.

[0050] Example 2

[0051] like Figure 7 and Figure 8 As shown, this embodiment is basically the same in structure as Embodiment 1, except that the sealing component includes a rotating disk 56, which is rotatably installed in the buffer chamber 1. The rotating disk 56 is sealed to the chamber wall where the chamber outlet 12 is located. The rotating disk 56 is provided with several vent holes 561 of different diameters. The rotating power device 57 drives the rotating disk 56 to rotate so that one of the vent holes 561 corresponds to the position of the outlet 23, or the rotating disk 56 blocks the chamber outlet 12. In this embodiment, the normally open vent 11 can be omitted, and the different diameter vent holes 561 on the rotating disk 56 can be used directly to change and adjust the outlet cross-sectional area. Of course, a normally open vent 11 can also be provided, which can also achieve the same change in the outlet cross-sectional area. The rotating power device 57 can be implemented by a geared motor.

[0052] Example 3

[0053] like Figure 9As shown, the structure of this embodiment is basically similar to that of embodiment 1, except that the opening mechanism is different. In this embodiment, a gas guide sleeve 58 is fixed on the buffer chamber 1. The gas outlet end of the gas guide sleeve 58 is connected to the gas outlet 12 of the chamber. The sealing component includes a piston rod 59 and a piston 510 installed at the end of the piston rod 59. The piston 510 is axially and slidably installed in the gas guide sleeve 58. The piston 510 divides the gas guide sleeve 58 into an outlet chamber 511 and an adjustment chamber. The side wall of the gas guide sleeve 58 is provided with a plurality of axially extending air inlets 512. The air inlets 512 connect the outlet chamber 511 with the inner cavity of the buffer chamber 1. The piston rod 59 is driven by the linear power device 51. In this embodiment, the linear power device 51 adopts an internal thread geared motor. The internal thread geared motor includes an internal threaded sleeve and a geared motor that drives the internal threaded sleeve to rotate. The internal threaded sleeve is threadedly connected to the piston rod 59 to form a screw and nut mechanism. Therefore, when the geared motor drives the internal threaded sleeve to rotate, it will drive the piston rod 59 to move axially. The piston rod 59 drives the piston 510 to move axially, thereby changing the size of the exhaust chamber 511 and thus changing the number of air inlets 512 that are connected to the exhaust chamber 511. This changes the cross-sectional area of ​​the connection between the buffer chamber 1 and the exhaust chamber 511, and also realizes the adjustment of the flow range.

[0054] Example 4

[0055] like Figure 10 As shown, the structure of this embodiment is basically similar to that of embodiment 3. An outer sleeve 515 is fixed to the outside of the buffer chamber, and a piston sleeve 517 is fixed inside the outer sleeve 515. A connecting cavity 516 is provided between the piston sleeve 517 and the outer sleeve 515. The sealing component includes a piston rod 59 and a piston 510 installed at the end of the piston rod 59. The piston 510 is axially and slidably installed in the piston sleeve 517. The piston 510 divides the piston sleeve 517 into an outlet chamber 511 and an adjustment chamber. The side wall of the piston sleeve 517 is provided with a plurality of axially distributed adjustment vents 514. The adjustment vents 514 connect the piston sleeve 517 with the connecting cavity 516. The outlet chamber 511 is connected to the chamber outlet of the buffer chamber. An outlet is provided on the outer sleeve 515. The piston rod is driven by the linear power device. The linear power device is driven by the internal thread reduction motor 513 in embodiment 3. In this embodiment, after the outer sleeve 515 is placed outside the buffer chamber, the outer sleeve 515 can be located in the empty space outside the buffer chamber, while the piston rod and the internal thread reduction motor 513 are located inside the buffer chamber. This can further reduce the volume of the buffer chamber and the overall sampler volume will be smaller.

[0056] The pneumatic system, motor and other actuators, and lead screw and nut mechanism mentioned in this embodiment are all conventional technologies. The specific structure, principle and other design of the motor and other transmission mechanisms are disclosed in detail in the 28th printing of the fifth edition of "Mechanical Design Handbook" in Beijing in April 2008. They belong to the prior art and their structures are clear and obvious. The above embodiments are only descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and alterations to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A gas buffer device of an individual sampler, comprising a buffer chamber, one of the chamber walls of the buffer chamber is an elastic diaphragm, an air inlet and a chamber air outlet are arranged on the buffer chamber, an air inlet pipe joint is installed at the air inlet, characterized in that: The inside of the buffer chamber is provided with an adjusting mechanism for adjusting the sectional area of the chamber outlet; the adjusting mechanism comprises a sealing member slidingly or rotatably installed in the buffer chamber, which is driven by a linear power device or a rotary power device to move between an open position and a closed position; the buffer chamber is further provided with a normally open air outlet, both the normally open air outlet and the chamber outlet being communicated with an air outlet channel for being communicated with an air outlet connector; the sealing member is in sealing engagement with the corresponding chamber outlet; the buffer chamber is provided with a detection port for detecting the pressure inside the buffer chamber; the outside of the buffer chamber is detachably fixed with a gas guide block, the position of the gas guide block corresponding to the positions of the chamber outlet and the normally open air outlet; the air outlet channel is arranged on the gas guide block; the gas guide block is provided with branch channels for connecting the chamber outlet and the normally open air outlet with the air outlet channel; the gas guide block and the buffer chamber are detachably installed with orifice plates corresponding to the chamber outlet and the normally open air outlet, respectively; each orifice plate is located between the corresponding branch channel and the chamber outlet or between the corresponding branch channel and the normally open air outlet.

2. A gas buffer for an individual sampler as defined in claim 1, characterized in that The sealing member comprises a rotary disc rotatably installed in the buffer chamber, the rotary disc being in sealing engagement with the chamber wall where the chamber outlet is located; the rotary disc is provided with a plurality of air vents with different diameters; the rotary power device drives the rotary disc to rotate so that one of the air vents corresponds to the position of the air outlet or the rotary disc seals the chamber outlet.

3. A gas buffer for an individual sampler as defined in claim 1, characterized in that: The sealing member comprises a sealing rod axially slidingly installed in the buffer chamber; the end of the sealing rod is in sealing engagement with the chamber outlet; the linear power device is installed in the buffer chamber and in transmission engagement with the sealing rod.

4. A gas buffer for an individual sampler as defined in claim 3, characterized in that: The linear power device comprises a speed reducer, the output shaft of the speed reducer being fixed with a driving gear; the sealing rod is fixed with a driven gear in mesh with the driving gear; the buffer chamber is fixed with a threaded sleeve; the sealing rod is threadedly installed in the threaded sleeve; the driving gear drives the driven gear to rotate and drives the sealing rod to axially move.

5. A gas buffer for an individual sampler as defined in claim 1, characterized in that: The buffer chamber is fixed with a gas guide sleeve, the air outlet end of the gas guide sleeve being communicated with the chamber outlet; the sealing member comprises a piston rod and a piston installed at the end of the piston rod; the piston is axially and sealingly slidingly installed in the gas guide sleeve; the piston divides the gas guide sleeve into an air outlet chamber and an adjusting chamber; the side wall of the gas guide sleeve is provided with a plurality of axially extending air inlet holes for connecting the air outlet chamber with the inner cavity of the buffer chamber; the piston rod is driven by the linear power device.

6. A gas buffer for an individual sampler as defined in claim 1, characterized in that: The outer sleeve is fixed outside the buffer chamber, a piston sleeve is fixed in the outer sleeve, a communication cavity is arranged between the piston sleeve and the outer sleeve, the sealing element comprises a piston rod and a piston installed on the end of the piston rod, the piston is axially and sealingly slidably installed in the piston sleeve, the piston divides the piston sleeve into a gas outlet chamber and an adjusting chamber, the side wall of the piston sleeve is provided with a plurality of axially distributed adjusting air holes which communicate the piston sleeve with the communication cavity, the gas outlet chamber communicates with the chamber gas outlet of the buffer chamber, a gas outlet is arranged on the outer sleeve, and the piston rod is driven by the linear power device.

7. A gas buffer for an individual sampler as defined in claim 1, characterized in that: The number of the elastic diaphragms is two, and the mounting recesses are arranged on the two opposite chamber walls of the buffer chamber, the elastic diaphragms are placed in the mounting recesses and are detachably fixed by the pressing rings.

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