Small flow gas sampling pump

Abstract

A small flow gas sampling pump, characterized by comprising an electric drive unit, a piston unit and a valve group connected in sequence, the electric drive unit is used for outputting linear reciprocating motion to the input end of the piston unit; the piston unit is provided with a first gas port on the output end to externally exhaust gas; the valve group comprises a second gas port, a first one-way unit and a second one-way unit, the second gas port is connected with the first gas port, the first one-way unit and the second one-way unit are connected in parallel on the second gas port, gas can only flow into the second gas port from the first one-way unit in one direction and flow out of the second gas port to the second one-way unit in one direction, and the electric drive unit and the piston unit are fixedly connected on the base. The present application realizes the automatic gas sampling demand with a simple structure, thereby solving the problem of inconvenient use of the small flow sampling device in the prior art, and realizing the technical effects of small flow and simple structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air quality monitoring, and particularly relates to a small-flow gas sampling pump. BACKGROUND

[0002] The gas sampling pump is a commonly used instrument for collecting gas in the field of atmospheric monitoring. The flow of the existing gas sampling pump is mostly above 1L / min, and the device is large in size and high in cost. For specific use scenarios requiring small-flow sampling, such gas sampling pumps are not suitable. Therefore, some manual sampling instruments suitable for small-flow sampling requirements appear in the prior art, but the use of such manual sampling instruments is relatively inconvenient, and the sampling accuracy is also affected by the operation experience.

[0003] Therefore, there is an urgent need in the prior art for an automatic sampling pump that can meet the requirements of specific use scenarios requiring small flow. SUMMARY

[0004] The present application aims at the defects of the prior art, and provides a small-flow gas sampling pump, which can solve the problem of inconvenient use of small-flow sampling instruments in the prior art.

[0005] To solve the above technical problems, the technical solutions of the present application are as follows:

[0006] A small-flow gas sampling pump, characterized in that: comprising an electric drive unit, a piston unit and a valve group connected in sequence, the electric drive unit is used to output linear reciprocating motion to the input end of the piston unit; the piston unit is provided with a first gas port on the output end to exhaust gas outward; the valve group comprises a second gas port, a first one-way unit and a second one-way unit, the second gas port is connected with the first gas port, the first one-way unit and the second one-way unit are connected in parallel on the second gas port, and gas can only flow from the first one-way unit to the second gas port in one direction and flow from the second gas port to the second one-way unit in one direction, and the electric drive unit and the piston unit are fixedly connected on the base.

[0007] Further, the electric drive unit comprises a drive motor and a reversing module, the output end of the drive motor is connected with the input end of the reversing module through a crank slider mechanism, and the output end of the reversing module is drivingly connected with the piston unit.

[0008] Further, the crank slider mechanism comprises a first connecting rod and a second connecting rod, one end of the first connecting rod is eccentrically hinged on the output end of the drive motor, the other end is hinged with the second connecting rod, and the second connecting rod is drivingly connected with the reversing module.

[0009] Further, the piston unit comprises a cylinder and a piston assembly, the cylinder is connected to the base through a quick-mounting clamp, the piston assembly comprises a piston body and a piston rod, one end of the piston rod is in transmission connection with the electric driving unit, the other end is coaxially connected with the piston body, and the piston body can reciprocate along the inside of the cylinder under the driving of the piston rod.

[0010] Further, the piston rod comprises a screw rod, a front fixing sheet, a gasket, a rear fixing sheet, a front locking nut, a rear locking nut and a threaded sleeve, the front fixing sheet, the gasket, the rear fixing sheet, the front locking nut, the rear locking nut and the threaded sleeve are coaxially connected on the screw rod in sequence from front to back, the open end of the piston body is provided with an annular turned edge, the annular turned edge is embedded between the front fixing sheet and the rear fixing sheet, and the output end of the electric driving unit is connected to the threaded sleeve.

[0011] Further, the quick-mounting clamp comprises a U-shaped clamping seat and a locking bolt, the U-shaped clamping seat is fixedly connected to the base, and the locking bolt is threadedly connected to the U-shaped clamping seat, and the cylinder is fixed between the locking bolt and the U-shaped clamping seat.

[0012] Further, the reversing module, the piston unit and the valve group are each provided with two groups, the reversing modules are connected to the inertial wheels of the output ends of the driving motors through the crank connecting rod mechanisms, and the connection positions are centrally and symmetrically distributed on the inertial wheels, the second one-way units are connected to the inlets of the bidirectional three-way valves, and the third one-way units are connected to the outlets of the bidirectional three-way valves.

[0013] Further, the electric driving unit comprises an electric push rod, and the electric push rod is in transmission connection with the piston unit.

[0014] Further, the electric push rod is fixedly connected to the base through a clamp and a supporting block.

[0015] Further, the electric driving unit is electrically connected to a motor controller and a power source in sequence, and the power source is an alternating current power source or a low-voltage direct current power source.

[0016] Compared with the prior art, the beneficial effects of the present application are that: the present application takes the electric driving unit as the source power, realizes the intermittent pressure pumping and draining action in cooperation with the first one-way unit and the second one-way unit in the mode of piston pumping, realizes the automatic gas sampling, realizes the automatic gas sampling demand with a simple structure, thereby solving the problem of inconvenient use of small-flow sampling instruments in the prior art, and realizing the technical effects of small flow and simple structure. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a small-flow gas sampling pump structure schematic diagram of the embodiment one of the present application.

[0018] Figure 2 Structure diagram of the piston rod of the embodiment one of the present application;

[0019] Figure 3 Structure diagram of the small flow gas sampling pump of the embodiment two of the present application;

[0020] Figure 4 Structure diagram of the small flow gas sampling pump of the embodiment three of the present application;

[0021] Figure 5 Structure diagram of the small flow gas sampling pump of the embodiment four of the present application;

[0022] Figure 6 Verification diagram of the small flow gas sampling pump of the present application for NO2 gas;

[0023] Figure 7 Verification diagram of the small flow gas sampling pump of the present application for formaldehyde gas.

[0024] Wherein: 100-electric drive unit, 110-driving motor, 111-electric push rod, 120-reversing module, 121-first connecting rod, 122-second connecting rod, 200-piston unit, 210-cylinder, 220-piston assembly, 221-piston main body, 222-piston rod, 2221-screw rod, 2222-front fixing plate, 2223-gasket, 2224-rear fixing plate, 2225-front locking nut, 2226-rear locking nut, 2227-threaded sleeve, 230-first gas port, 300-valve group, 310-first one-way unit, 320-second one-way unit, 330-second gas port, 400-base, 500-inertia wheel, 510-U-shaped clamping seat, 520-locking bolt, 530-supporting block, 540-clamp, 550-fastening bolt, 600-bidirectional tee valve, 700-third one-way unit, 800-alternating current power supply, 900-motor controller, 1000-low-voltage direct current power supply, 1100-voltage boosting device. DETAILED DESCRIPTION

[0025] In order to deepen the understanding of the present application, we will make a further detailed description of the present application combined with the drawings below, which is only used to explain the present application and does not constitute a limitation on the protection scope of the present application.

[0026] Embodiment one

[0027] Figure 1 、 2Embodiment one of a small flow gas sampling pump is shown, including an electric driving unit 100, a piston unit 200 and a valve group 300. The electric driving unit 100 is configured to output linear reciprocating motion. The input end of the piston unit 200 is in transmission connection with the output end of the electric driving unit 100, and the output end of the piston unit 200 forms a first gas port 230 for pumping gas. The valve group 300 includes a second gas port 330 connected with the first gas port 230, a first one-way unit 310 for controlling the one-way flow of gas into the second gas port 330, and a second one-way unit 320 for controlling the one-way flow of gas out of the second gas port 330, wherein the first one-way unit 310 and the second one-way unit 320 intersect and are connected in parallel to the second gas port 330.

[0028] In use, in one stroke, the electric driving unit 100 pulls the piston unit 200 to make a backward action, so that the first one-way unit 310 of the valve group 300 is opened and the second one-way unit 320 is closed, so that the external gas enters the piston unit 200 through the first one-way unit 310 and is temporarily stored in the rodless cavity of the piston unit 200, and the volume of the rodless cavity is also the determining factor of the intermittent pumping flow, so the stroke can be defined as the suction stroke; after the electric driving unit 100 reverses and enters another motion stroke, the piston unit 200 is pushed to make a pushing action, so that the first one-way unit 310 of the valve group 300 is closed and the second one-way unit 320 is opened, so that the gas stored in the rodless cavity of the piston unit 200 is pressed out, which is generally discharged into a sampling container for later detection, so the stroke can be defined as the exhaust stroke.

[0029] The present application uses the electric driving unit 100 as the source power, uses the piston suction mode, cooperates with the first one-way unit 310 and the second one-way unit 320 which are opposite to each other, realizes the intermittent pressure pumping action, and realizes the automatic gas sampling, so as to realize the automatic gas sampling demand with simple structure, thereby solving the problem of inconvenient use of small flow sampling instruments in the prior art, and realizing the technical effects of small flow and simple structure.

[0030] The electric driving unit 100 comprises a driving motor 110 and a reversing module 120. The driving motor 110 is configured to output rotary motion, and the input end of the reversing module 120 is drivingly connected to the output end of the driving motor 110 through a crank slider mechanism. Preferably, the driving motor 110 is a servo motor or a stepper motor to improve the precision of small-flow sampling. Since the power required by the small-flow gas sampling is not large, the motor can be a small-power motor to better reduce the cost of the whole machine. The crank slider mechanism is selected as the transmission mechanism to further reduce the cost of the whole machine, considering the reliability and market price of the mechanism. Preferably, the crank slider mechanism comprises a first connecting rod 121 eccentrically hinged to the output end of the driving motor 110 and a second connecting rod 122 hinged to the other end of the first connecting rod 121, and the second connecting rod 122 is linearly slidingly connected to the reversing module 120. The driving motor 110 is further connected to an alternating current power supply 800 and a motor controller 900.

[0031] The small-flow gas sampling pump further comprises a base 400, the electric driving unit 100 is mounted on the base 400, and the base 400 is further connected to a quick-mount clamp detachably connected to the piston unit 200. Generally, to meet the requirements of small-flow gas sampling, the piston unit 200 can be selected in specifications of 1 mL, 5 mL, 50 mL, 250 mL, etc. to improve the application range of the small-flow gas sampling pump and facilitate switching between sampling environments with different flow requirements. Preferably, one end of the piston unit 200 is formed with an annular or rectangular outward turning edge, the quick-mount clamp comprises a U-shaped clamping seat 510 fixed on the base 400, one end of the outward turning edge abuts against the inner wall on one side of the U-shaped clamping seat 510, and the U-shaped clamping seat 510 is further connected to a locking bolt 520, which locks the piston unit 200 on the U-shaped clamping seat 510 to realize quick mounting and dismounting of the piston unit 200 on the base 400.

[0032] The piston unit 200 comprises a cylinder 210 and a piston assembly 220. The cylinder 210 is detachably connected to the quick-mount clamp. As shown in Figure 2As shown, the piston assembly 220 includes a piston body 221 slidingly and sealingly connected in the cylinder barrel 210, and a piston rod 222 coaxially and detachably connected at one end of the piston body 221, and detachably connected at the other end of the piston rod 222 to the output end of the electric drive unit 100. When the piston unit 200 is disassembled, there are two interfaces that need to be disassembled between the piston unit 200 and the base 400, one between the cylinder barrel 210 and the quick-mount clamp, and the other between the piston assembly 220 and the output end of the electric drive unit 100. Preferably, the piston rod 222 includes a screw rod 2221, and the screw rod 2221 is sequentially connected from the head to the front fixing sheet 2222, the gasket 2223, the rear fixing sheet 2224, the front locking nut 2225, the rear locking nut 2226, and the threaded sleeve 2227. The piston body 221 is made of rubber and has a cap shape, and the open end of the piston body 221 is formed with an inwardly turned annular turned edge; the annular turned edge is clamped between the front fixing sheet 2222 and the rear fixing sheet 2224.

[0033] Preferably, the piston assembly 220 and the electric drive unit 100 can also be fixedly connected in a non-removable manner, such as welding or integral molding; that is, when the piston unit 200 needs to be replaced, only the cylinder barrel 210 needs to be replaced, thereby reducing the cost of spare parts and further reducing the cost.

[0034] Preferably, the control module is further connected to the electric drive unit 100 and the pressure sensor, and the pressure sensor is located between the piston body 221 and the piston rod 222, so that the control module is configured to:

[0035] in response to the measured pressure measured by the pressure sensor being not lower than the first pressure threshold and lower than the second pressure threshold, the output end of the electric drive unit 100 starts to output reverse motion, wherein the second pressure threshold is greater than the first pressure threshold;

[0036] in response to the measured pressure measured by the pressure sensor being not lower than the second pressure threshold, the output end of the electric drive unit 100 starts to output reverse motion and stops at the end of the stroke of the reverse motion.

[0037] Thus, by measuring the pressure with the pressure sensor, the rotation angle of the electric drive unit 100 is controlled without adjusting the length of the piston rod 222, which is more convenient to use.

[0038] Verification of the accuracy of the above embodiment:

[0039] The small-flow gas sampling pump of Example 1 is used to sample nitrogen dioxide and formaldehyde in air for 24 hours, and the daily average concentration is measured and compared with the reference concentration to verify the accuracy of the small-flow gas sampling pump of Example 1, and the results are as follows.

[0040] Table 1 - accuracy verification results of the small flow gas sampling pump of Example 1

[0041]

[0042] From the above Table 1 and Figure 6 , 7 It can be seen that the pollutant concentration obtained by analysis using the small flow gas sampling pump of Example 1 is basically within ± 30% of the reference concentration. For NO2, the reference concentration is the concentration of the national monitoring station, and the national monitoring station is separated from the sampling site of the sampling pump of the application by a certain distance; for formaldehyde, the reference concentration of some experiments is low, which may cause an increase in error. At the same time, atmospheric sampling is disturbed by many factors such as wind speed. Therefore, from the above results, the small flow gas sampling pump of the present embodiment has good accuracy.

[0043] Flow long-term stability test of the small flow gas sampling pump of the application:

[0044] The flow of the small flow gas sampling pump of the application is measured for the first time using a soap film flowmeter, and after the small flow gas sampling pump of the application has been used for one year, the flow is measured again using the same method. By comparing the measurement results before and after, the long-term stability of the flow of the small flow gas sampling pump of the application is tested.

[0045] Table 2 - long-term stability test results of the flow of the small flow gas sampling pump of the application

[0046]

[0047] Table 2 shows the long-term stability test results of the flow of the small flow gas sampling pump of the present embodiment. It can be seen that the relative deviation of the measurement results before and after is within ± 7%, and the small flow gas sampling pump of the present embodiment has good long-term stability of flow.

[0048] Example 2

[0049] As Figure 3As shown, the reversing module 120, the piston unit 200, and the valve group 300 are each provided with two groups, and the piston unit 200 is provided in one-to-one correspondence with the reversing module 120; the output end of the driving motor 110 is connected with an inertia wheel 500, and the input ends of the two reversing modules 120 are connected on the rim of the inertia wheel 500 and are symmetrically arranged relative to the center of the inertia wheel 500, so as to form two crank slider mechanisms sharing the same driving motor 110. The valve group 300 and the piston unit 200 are provided in one-to-one correspondence, the outlets of the second one-way units 320 of the two valve groups 300 are respectively connected on the two inlets of the same bidirectional three-way valve 600, and the outlet of the bidirectional three-way valve 600 is connected with the third one-way unit 700 for discharging gas. The working process of the bidirectional three-way valve 600 is as follows: when the pressure of one inlet is greater than that of the other inlet, the one inlet and the outlet are communicated, and the other inlet is in a closed state; vice versa. By arranging the bidirectional three-way valve 600 at the exhaust gas intersection position of the two valve groups 300, the exhaust gas is prevented from flowing back to the exhaust pipeline of the other valve group 300, and the sampling gas of different time periods is prevented from being mixed, so as to ensure the accuracy of sampling. The remaining structures are the same as those of the first embodiment.

[0050] In work, when one piston unit 200 is in the suction stroke, the other piston unit 200 is in the exhaust stroke; vice versa, so as to realize continuous gas supply and avoid the problem of incoherent sampling caused by intermittent gas supply.

[0051] Preferably, the reversing module 120, the piston unit 200, and the valve group 300 can be expanded to more than three groups, and each piston unit 200 is provided in one-to-one correspondence with the reversing module 120; the output end of the driving motor 110 is connected with a crankshaft, and the input ends of the reversing modules 120 are connected on the connecting rod shaft necks of the crankshaft. By controlling the piston units 200 to be in different stroke stages at the same time through the crankshaft, the tightness of stroke connection is improved, and the coherence of sampling is better improved. A reversing valve is added at the exhaust pipeline intersection of the valve groups 300, so as to ensure that the exhaust gas is communicated with the sampling container and avoid the mixing of sampling gas.

[0052] Example Three

[0053] As Figure 4As shown, the electric drive unit 100 includes an electric push rod 111, which can be a combination of a motor and a screw nut mechanism, or an electromagnetic push rod mechanism, or other types of push rod mechanisms that output linear reciprocating power with electric energy. The electric push rod 111 is coaxially connected with the piston assembly 220 through an internally threaded rod. The piston assembly 220 is connected with the internally threaded rod through a threaded connection, and the clamp 540 is used to fix the cylinder 210, which is then fixed on the base 400 through the fastening bolt 550. The electric push rod 111 is fixed on the base 400 through the clamp 540 and the support fastener 530. The remaining structure is the same as that of the first embodiment. The electric push rod 111 can intermittently perform linear extension and retraction, driving the piston assembly 220 to extend and retract, thereby achieving intermittent air suction and exhaust. The power input end of the electric push rod 111 is connected in sequence with the motor controller 900 and the alternating current power supply 800 through wires, wherein the motor controller 900 can adjust the extension and retraction frequency of the electric push rod 111 and thus adjust the air suction flow. This power supply scheme can make the electric push rod 111 in this embodiment adapt to the direct current or alternating current power supply of the commercial power supply.

[0054] Embodiment four

[0055] Figure 5 As shown, the electric push rod 111 is connected in sequence with the motor controller 900, the voltage boosting device 1100 and the low-voltage direct current power supply 1000 through wires. The low-voltage direct current power supply 1000 can be connected with the voltage boosting device 1100 through a USB plug, a type-c plug, a Lightning plug, a single column plug, etc. The low-voltage direct current power supply 1000 can be a mobile power supply, a vehicle-mounted socket, etc., and can improve the power supply adaptation range of the small-flow gas sampling pump of the present application through the voltage boosting of the voltage boosting device 1100.

[0056] The above specific embodiments are only for illustrating the technical concept and structural features of the present application, and the purpose is to enable relevant persons skilled in the art to implement it, but the above content does not limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the spirit and essence of the present application shall fall within the protection scope of the present application.

Claims

1. A low flow gas sampling pump characterized by: The application relates to a piston unit (200), a valve group (300) and an electric driving unit (100) connected in sequence, wherein the electric driving unit (100) is used for outputting linear reciprocating motion to an input end of the piston unit (200); the piston unit (200) is provided with a first gas port (230) on an output end, and is used for externally discharging gas; the valve group (300) comprises a second gas port (330), a first one-way unit (310) and a second one-way unit (320), the second gas port (330) is connected with the first gas port (230), the first one-way unit (310) and the second one-way unit (320) are connected in parallel on the second gas port (330), gas can only flow from the first one-way unit (310) to the second gas port (330) in one direction, and can only flow from the second gas port (330) to the second one-way unit (320) in one direction, and the electric driving unit (100) and the piston unit (200) are fixedly connected on a base (400). The electric driving unit (100) comprises a driving motor (110) and a reversing module (120), an output end of the driving motor (110) is connected with an input end of the reversing module (120) through a crank slider mechanism, and an output end of the reversing module (120) is transmissionally connected with the piston unit (200). The piston unit (200) comprises a cylinder barrel (210) and a piston assembly (220), the cylinder barrel (210) is connected on the base (400) through a quick-mounting clamp, the piston assembly (220) comprises a piston main body (221) and a piston rod (222), one end of the piston rod (222) is transmissionally connected with the electric driving unit (100), the other end is coaxially connected with the piston main body (221), and the piston main body (221) can reciprocate along the inside of the cylinder barrel (210) under the driving of the piston rod (222). The piston rod (222) comprises a screw rod (2221), a front fixing sheet (2222), a gasket (2223), a rear fixing sheet (2224), a front locking nut (2225), a rear locking nut (2226) and a threaded sleeve (2227), the front fixing sheet (2222), the gasket (2223), the rear fixing sheet (2224), the front locking nut (2225), the rear locking nut (2226) and the threaded sleeve (2227) are coaxially connected on the screw rod (2221) in sequence from front to back, an open end of the piston main body (221) is provided with an annular turning edge, the annular turning edge is embedded between the front fixing sheet (2222) and the rear fixing sheet (2224), and an output end of the electric driving unit (100) is connected on the threaded sleeve (2227). The quick-mounting clamp comprises a U-shaped clamping seat (510) and a locking bolt (520), the U-shaped clamping seat (510) is fixedly connected on the base (400), the locking bolt (520) is threadedly connected on the U-shaped clamping seat (510), and the cylinder barrel (210) is fixed between the locking bolt (520) and the U-shaped clamping seat (510). The reversing module (120), the piston unit (200), and the valve group (300) are each provided with two groups, the reversing module (120) is connected to the inertia wheel (500) of the output end of the driving motor (110) through a crank slider mechanism, and the connection positions are centrally symmetrically distributed on the inertia wheel (500), the outlets of the second one-way units (320) of the two groups of valve groups (300) are respectively connected to two inlets of the same bidirectional three-way valve (600), the outlet of the bidirectional three-way valve (600) is connected to the third one-way unit (700) for external air outlet, when the pressure of one inlet is greater than that of the other inlet, the one inlet and the outlet are communicated, and the other inlet is in a closed state.

2. The low flow gas sampling pump of claim 1, wherein: The crank slider mechanism comprises a first connecting rod (121) and a second connecting rod (122), one end of the first connecting rod (121) is eccentrically hinged to the output end of the driving motor (110), the other end is hinged to the second connecting rod (122), and the second connecting rod (122) is drivingly connected to the reversing module (120).

3. The low flow gas sampling pump of claim 1, wherein: The electric driving unit (100) comprises an electric push rod (111), and the electric push rod (111) is drivingly connected to the piston unit (200).

4. The low flow gas sampling pump of claim 3, wherein: The electric push rod (111) is fixedly connected to the base (400) through a clamp (540) and a support block (530).

5. The low flow gas sampling pump of claim 1, wherein: The electric driving unit (100) is electrically connected to a motor controller (900) and a power supply in sequence, and the power supply is an alternating current power supply (800) or a low-voltage direct current power supply (1000).

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