CN110346265A - A kind of Permeometer - Google Patents

Abstract

The invention relates to the technical field of fabric performance detection devices, in particular to a fabric air permeability tester, which includes a frame, a fan, a gas delivery unit, an air cavity, a venting orifice, a holder and a differential pressure gauge. The conveying unit communicates with the air cavity, the gas conveying unit includes a conveying pipeline, a solenoid valve and a flow meter, one end of the conveying pipeline communicates with the fan, and the other end communicates with the air chamber, the solenoid valve is arranged on the conveying pipeline, the The flowmeter is set on the conveying pipeline between the solenoid valve and the air cavity, the air-permeable orifice plate is set directly above the air cavity, and the holder is set directly above the air-permeable orifice plate, and the clamper is used for fabric test The sample is compressed on the air-permeable orifice plate, and the differential pressure gauge is respectively connected to the air cavity and the inner cavity of the holder. This solution will not block the pipeline, and it will work more stably for a long time. It is suitable for constant air pressure measurement and air volume test. The operation is simpler, the test data is more accurate, and the market competitiveness is stronger.

Description

A fabric air permeability tester

technical field

The invention relates to the technical field of fabric performance detection devices, in particular to a fabric air permeability tester.

Background technique

Fabric is a flat and soft piece formed by crossing, knotting or bonding small and long objects. As the main material of clothing, its various use indicators are also highly valued by the garment industry. As one of the main parameters of the fabric use index, air permeability greatly affects the comfort of the fabric. Winter clothes need lower air permeability to keep warm, while summer clothes need higher air permeability to keep cool.

At present, the air permeability of fabrics is generally tested by an air permeability testing device. The air permeability test device directly relies on a simple small nozzle to inhale air, and obtains the pressure difference between the upper and lower surfaces of the fabric by quantifying the amount of sucked air, and then obtains the air permeability index according to the relevant calculation formula. However, when using the above quantitative pressure measurement air permeability test device, the nozzle structure is small and easily blocked by dust, the long-term air permeability test has poor stability, and the test results are not accurate enough. Affected by many factors, the test data is inaccurate and affects the results of fabric air permeability analysis.

Contents of the invention

For this reason, it is necessary to provide a fabric air permeability tester to solve the problem that the existing air permeability test device is prone to nozzle clogging, poor long-term working stability, and the air volume control accuracy of the quantitative pressure measurement test device is not high, resulting in poor test data accuracy. The problem.

In order to achieve the above object, the inventor provides a fabric air permeability tester, which includes a frame, a blower fan, a gas delivery unit, an air chamber, a venting orifice, a holder and a differential pressure gauge, and the blower fan passes through The gas delivery unit communicates with the air cavity, and the gas delivery unit includes a delivery pipeline, a solenoid valve and a flow meter. One end of the delivery pipeline communicates with the fan, and the other end communicates with the air cavity. The solenoid valve is arranged on the delivery pipeline. The flowmeter is set on the conveying pipeline between the solenoid valve and the air chamber, the air chamber is fixed on the frame, the air-ventilating orifice plate is arranged directly above the air-cavity, and the holder is arranged on the air-ventilating orifice plate There is a gap for placing the fabric sample between the holder and the air-perforated plate, the holder is used to press the fabric sample on the air-perforated plate, and the differential pressure gauge communicates with the air cavity and the clamp respectively. The pressure differential gauge is used to measure the air pressure difference between the upper surface and the lower surface of the fabric sample.

As a preferred structure of the present invention, the holder includes an upper pressure head, a gland, a guide shaft, a pressure spring, a pressure sample head, a pressure plate and a blocking plate, and the upper pressure head and the pressure plate are hollowly sleeved on the pressure sample. Outside the head, the pressure plate is located above the upper pressure head, and the guide shaft is evenly arranged outside the pressure head, one end of the guide shaft is fixed with the pressure head, and the other end is sleeved in the shaft hole of the upper pressure head It can slide along the shaft hole, the pressure spring is sleeved outside the guide shaft, and the blocking plate is fixed on the upper end of the upper pressing head.

As a preferred structure of the present invention, the tester also includes a clamping and lifting mechanism, and the clamping and lifting mechanism includes a connecting long plate, a swing arm, a base, a gas spring, an electromagnet, and a limit rod. The connecting long plate is arranged on the swing arm, and one end of the connecting long plate is fixed with the holder. The other end is connected with the swing arm, the limit rod is connected with the electromagnet, and the limit rod is inserted into or moved out of the limit slot on the swing arm under the drive of the electromagnet.

As a preferred structure of the present invention, the holder also includes a hasp and a positioning pin, the hasp is arranged at one end of the upper pressing head, and the positioning pin is arranged on the side wall of the upper pressing head, the A positioning hole is opened on the connecting long plate, and the positioning hole is matched with a positioning pin, and the connecting long plate is connected with the upper pressing head through a buckle.

As a preferred structure of the present invention, at least two contact holes are opened on the side of the connecting long plate facing the upper indenter, and a contact rod is provided on the side wall of the upper indenter, and the contact rod can be extended into Contact conduction in the contact hole.

As a preferred structure of the present invention, the holder further includes a rubber washer, and the rubber washer is arranged on the lower end surface of the sampling head.

As a preferred structure of the present invention, the holder further includes a pipe joint, one end of the pipe joint communicates with the central inner hole of the sampling head, and the other end of the pipe joint connects with the differential pressure gauge.

As a preferred structure of the present invention, there are at least two groups of gas delivery units, and at least two groups of gas delivery units communicate with the blower and the air cavity respectively.

As a preferred structure of the present invention, a rubber pad is also provided between the air chamber and the air-perforated plate, and the air chamber, the air holes of the air-perforated plate and the central inner hole of the pressure sample head are aligned up and down.

As a preferred structure of the present invention, the upper end surface of the air chamber is also provided with an annular accommodation groove, the annular accommodation groove is provided with a support net, and the inside of the air chamber is also provided with a filter screen. The gas in the filter enters the delivery pipeline through the filter screen.

Different from the prior art, the above-mentioned technical solution has the following advantages: a fabric air permeability tester of the present invention, by placing the fabric sample on the air-perforated plate, and compressing the fabric sample with a clamper while preventing the edge from Leakage, start the fan, the fan pumps air, the gas enters the fan through the holder, the fabric sample, the vent plate, the air cavity and the gas delivery unit in turn, and is discharged to the outside of the frame. The gas delivery unit is set The solenoid valve is used to control the on-off of the conveying channel. The gas drawn in by the fan enters the conveying pipeline from the air cavity, and the gas flow is measured by the flow meter installed on the conveying pipeline. The differential pressure gauge is respectively connected to the air cavity and the inner cavity of the holder , The differential pressure gauge is used to measure the air pressure difference between the upper surface and the lower surface of the fabric sample. In this scheme, by fixing the air pressure difference between the upper and lower surfaces of the fabric sample, when the differential pressure meter measures the air pressure difference between the upper and lower surfaces of the fabric sample to meet the specified requirements, the flow value currently measured on the flow meter is the fabric sample’s pressure difference. air flow. The fabric air permeability tester of the present invention is ventilated through a large pipeline without blockage, and it works more stably for a long time. At the same time, it is suitable for the test method of measuring the air volume at a constant air pressure. The test is simpler, the test data is more accurate, and the market competitiveness is stronger. powerful.

Description of drawings

Fig. 1 is a schematic cross-sectional structure schematic diagram of a front view of a fabric air permeability tester described in a specific embodiment;

Fig. 2 is a schematic view of the oblique view of a fabric air permeability tester described in the specific embodiment;

Fig. 3 is a schematic cross-sectional structure diagram of a holder in a fabric air permeability tester described in a specific embodiment.

Explanation of reference signs:

1. Rack;

2. Fan;

3. Gas delivery unit;

31. Conveying pipeline; 32. Solenoid valve; 33. Flow meter;

4. Air cavity;

5. Ventilation hole plate;

6. Holder;

61, upper pressure head; 610, positioning pin; 620, contact rod;

62. Gland;

63. Guide shaft;

64. Compression spring;

65. Pressure sample head; 650. Blocking plate;

66. Pressure plate;

67. Buckle

68. Rubber gasket;

69. Pipe joints;

7. Differential pressure gauge;

8. Fabric samples;

9. Clamping and lifting mechanism;

91. Connect the long board;

92. arm swing;

93. Base;

94. Gas spring;

95. Electromagnet;

96. Limit rod;

97, pin shaft;

98, buckle;

10. Rubber pad;

11. Support net;

12. Filter screen.

Detailed ways

In order to explain in detail the technical content, structural features, achieved goals and effects of the technical solution, the following will be described in detail in conjunction with specific embodiments and accompanying drawings.

Please refer to Fig. 1 to Fig. 3, the present invention provides a kind of fabric gas permeability tester, described tester comprises frame 1, blower fan 2, gas conveying unit 3, air chamber 4, air perforated plate 5, clamper 6 and a pressure differential gauge 7, the fan 2 communicates with the air cavity 4 through the gas delivery unit 3, the gas delivery unit 3 includes a delivery pipeline 31, a solenoid valve 32 and a flow meter 33, and one end of the delivery pipeline 31 communicates with the fan 2 , the other end communicates with the air cavity 4, the electromagnetic valve 32 is arranged on the delivery pipeline 31, the flowmeter 33 is arranged on the delivery pipeline 31 between the electromagnetic valve 32 and the air cavity 4, and the air cavity 4 is fixed on On the frame 1, the vent hole plate 5 is arranged directly above the air chamber 4, the holder 6 is arranged directly above the vent hole plate 5, and there is a gap between the holder 6 and the vent hole plate 5 for The gap where the fabric sample 8 is placed, the holder 6 is used to press the fabric sample 8 on the air-permeable orifice plate 5, the differential pressure gauge 7 communicates with the air chamber 4 and the inner cavity of the clamper 6 respectively, and the differential pressure gauge 7 is used to measure the air pressure difference between the upper surface and the lower surface of the fabric sample 8. The frame 1 is used as the main structure of the tester of the present invention, and is used to install and carry the fan 2, the gas delivery unit 3, the air cavity 4, the vent plate 5, the holder 6 and the differential pressure gauge 7 and other components. Preferably, the frame 1 is made of stainless steel, and the frame 1 is not prone to corrosion, which will affect the normal use of the device.

The fan 2 is an exhaust fan and a negative pressure fan, which are used to suck gas from the outside of the body into the holder 6 through the gas delivery unit 3 and the air cavity 4, so as to perform the air permeability test of the fabric sample 8. The gas delivery unit 3 is used for gas delivery between the fan 2 and the air cavity 4 . Specifically, the gas delivery unit 3 includes a delivery pipeline 31, a solenoid valve 32 and a flow meter 33, the delivery pipeline 31 is used for the delivery of gas, the solenoid valve 32 is used to control the on-off of the delivery channel, and the flow meter 33 is used for The real-time measurement of the air volume passing through the delivery pipe 31 is the gas flow rate passing through the fabric sample 8 . The air chamber 4 serves as a gas accommodating space, and the gas enters the air chamber 4 through the central through hole of the holder 6 through the fabric sample 8 and the air-permeable orifice plate 5 , and then is transported by the gas delivery unit 3 . The gas is transported through the above-mentioned large pipeline flow path, and there will be no clogging of the nozzle in the traditional test device, and the long-term work is more stable. The air perforated plate 5 is used to carry the flat fabric sample 8 and at the same time limit the test area of the fabric sample 8, which is more convenient for the air permeability test. The holder 6 is used to firmly fix the fabric sample 8 on the air-permeable orifice plate 5, on the one hand to prevent the fabric sample 8 from being blown away and shifted, and on the other hand to fix the outer edge of the fabric sample 8 Seal to prevent inaccurate test results due to gas leakage. The differential pressure gauge 7 communicates with the air cavity 4 and the inner cavity of the holder 6 respectively, and the differential pressure gauge 7 is used to measure the air pressure difference between the upper surface and the lower surface of the fabric sample 8 .

In this embodiment, the experimenter first places a ventilating orifice plate 5 that meets the requirements on the upper opening of the air cavity 4, and spreads the fabric sample 8 on the venting orifice plate 5, and then passes the clamp 6 to the fabric sample 8. Clamping is performed, and then the fan 2 is started to run to start the air permeability test. The air flow is passed through the fabric sample 8, the venting orifice plate 5, the air chamber 4, the gas delivery unit 3 and the fan 2 sequentially from the holder 6. When the fan 2 is running, after the gas passes through the fabric sample 8, a certain pressure difference is generated on the upper surface and the lower surface of the fabric sample 8, and the pressure difference between the upper and lower surfaces of the fabric sample 8 is measured by the differential pressure meter 7 set in the tester . When the pressure difference detected by the differential pressure meter 7 meets the requirements of the system, the flow value measured by the flow meter 33 arranged on the delivery pipeline 31 is the air permeability of the fabric sample 8 under the current test area. The experimenter can obtain the air permeability index according to the relevant calculation formula.

In this embodiment, a fabric air permeability tester, the fabric sample 8 is placed on the air-permeable orifice plate 5, and the fabric sample 8 is pressed tightly by the holder 6 while preventing air leakage at the edge, and the fan 2 is started. 2 to pump air, and the gas enters into the fan 2 through the holder 6, the fabric sample 8, the vent plate 5, the air cavity 4 and the gas delivery unit 3 in turn, and is discharged to the outside of the frame 1, and the gas delivery unit 3 A solenoid valve 32 is arranged on the top to control the on-off of the conveying channel. The gas drawn in by the fan 2 enters the conveying pipeline 31 from the air chamber 4, and the gas flow is measured by the flow meter 33 arranged on the conveying pipeline 31. The differential pressure gauge 7 respectively The air cavity 4 communicates with the inner cavity of the holder 6, and the differential pressure gauge 7 is used to measure the air pressure difference between the upper surface and the lower surface of the fabric sample 8. In this scheme, by fixing the air pressure difference between the upper and lower surfaces of the fabric sample 8, when the differential pressure meter 7 measures that the air pressure difference between the upper and lower surfaces of the fabric sample 8 meets the specified requirements, the flow value currently measured on the flow meter 33 is Air permeability of fabric sample 8. The fabric air permeability tester of the present invention is ventilated through a large pipeline without blockage, and it works more stably for a long time. At the same time, it is suitable for the test method of measuring the air volume at a constant air pressure. The test is simpler, the test data is more accurate, and the market competitiveness is stronger. powerful.

As shown in Figures 1 and 3, in a specific embodiment, the holder 6 includes an upper pressure head 61, a gland 62, a guide shaft 63, a compression spring 64, a pressure sample head 65, a pressure plate 66 and a blocking plate 650 , the upper pressing head 61 and the pressing plate 66 are both hollowly sleeved outside the pressing head 65, the pressing plate 66 is located above the upper pressing head 61, the guide shaft 63 is evenly arranged outside the pressing head 65, and the guiding shaft 63 One end is fixed with the pressure sample head 65, the other end is sleeved in the shaft hole of the upper pressure head 61 and the end is provided with a gland 62, the guide shaft 63 can slide along the shaft hole, and the pressure spring 64 is sleeved on the guide shaft 63 Besides, the blocking plate 650 is fixed on the upper end of the upper pressing head 61 . In this embodiment, the experimenter presses down the holder 6 through the pressing plate 66, driving the upper pressing head 61 to move downwards, so that the guide shaft 63 can move along the shaft hole of the upper pressing head 61 until the sleeve The compression spring 64 arranged outside the guide shaft 63 abuts against the upper pressing head 61, the compression spring 64 contracts, and the spring generated by it pushes the sampling head 65 downward, so that the sampling head 65 moves downward, so that the sampling head 65 The fabric sample 8 is pressed tightly on the air perforated plate 5 . The setting function of the compression spring 64 is to be able to adapt to fabric samples 8 of different thicknesses, so that the application range of the tester of the present invention is wider and the market competitiveness is stronger.

Please refer to Fig. 1, as a preferred embodiment of the present invention, the tester also includes a clamping and lifting mechanism 9, and the clamping and lifting mechanism includes a connecting long plate 91, a swing arm 92, a base 93, a gas spring 94. The electromagnet 95 and the limit rod 96, the connecting long plate 91 is arranged on the swing arm 92, one end of the connecting long plate 91 is fixed with the holder 6, the swing arm 92 is hinged and fixed with the base 93, and the swing The arm 92 can rotate around its hinge point with the base 93, one end of the gas spring 94 is connected with the frame 1, and the other end is connected with the swing arm 92, the limit rod 96 is connected with the electromagnet 95, and the limit The rod 96 is inserted into or moved out of the limit slot on the swing arm 92 driven by the electromagnet 95 . Preferably, the swing arm 92 and the base 93 are hinged and fixed by a pin 97 . In this embodiment, when the fabric sample 8 is pressed down and clamped by the clamper 6, the upper pressing head 61 can drive the connecting long plate 91 to move downward during the pressing down process, so that the hinged joint with the base 93 The swing arm 92 moves downward, and when the vertical bar section of the swing arm 92 moves downward to a designated position, the electromagnet 95 is energized to control the limit rod 96 to be inserted into the limit slot of the base 93, and the swing arm 92 is limited. position, and then fix the position of the clamper 6, so that the clamper 6 can press the fabric sample 8 on the air-perforated plate 5. At this time, one end of the swing arm 92 rotates downward, and the other end must move upward. , so that the gas spring 94 is stretched, and now the gas spring 94 has a downward elastic restoring force. When the holder 6 needs to be lifted, the electromagnet 95 only needs to control the limit rod 96 to move out of the limit groove of the swing arm 92, and under the action of the restoring force of the gas spring 94, the swing arm 92 moves up and down, thereby making the connection Both the long plate 91 and the holder 6 are lifted up, so that the installation and replacement of the fabric sample 8 is more convenient. Preferably, the spring is a traction gas spring 94 . The traction gas spring 94 (tension gas spring 94) is a special gas spring 94. Other gas springs 94 are in the longest position when they are free, that is, they are from the longest position to the shortest position after being subjected to external force. The position moves, and the free state of traction type gas spring 94 is in the shortest position, runs from the shortest point to the longest point when being pulled. The traction gas spring 94 is set to have a smaller volume and is more convenient for installation.

Referring to Fig. 1 to Fig. 3, as a preferred embodiment of the present invention, the holder 6 further includes a buckle 67 and a positioning pin 610, the buckle 67 is arranged at one end of the upper pressing head 61, the The positioning pin 610 is arranged on the side wall of the upper pressing head 61, and a positioning hole is provided on the connecting long plate 91, and the positioning hole is adapted to the positioning pin 610, and the connecting long plate 91 and the upper pressing head 61 pass through Hasp 67 is connected. Buckle 67, as its name implies, is an object that is lapped on two objects and is used for fastening. In this solution, a positioning pin 610 is provided on the side wall of the upper pressing head 61, and a positioning hole is provided at a corresponding position on the connecting long plate 91. Through the cooperation of the positioning pin 610 and the positioning hole, the connecting long plate 91 and the positioning hole can be realized. The upper pressing head 61 of the holder 6 is quickly connected, and the docking accuracy is high, and then the connecting long plate 91 and the upper pressing head 61 are further fixed by the buckle 67, which is firmly fixed and easy to disassemble.

In some specific embodiments, at least two contact holes are opened on the side of the connecting long plate 91 facing the upper pressure head 61, and a contact rod 620 is provided on the side wall of the upper pressure head 61, and the contact rod 620 is arranged on the side wall of the upper pressure head 61. The rod 620 can extend into the contact hole to contact conduction. In this embodiment, the touch control and the touch rod 620 form a trigger structure, and the specification of the current holder 6 is judged by the number of contact conductions, and then the specification of the fabric sample 8 currently undergoing air permeability test is judged , so as to select an appropriate air pressure difference and gas delivery unit 3 for testing. In a specific embodiment, three contact holes are arranged side by side on the side wall of the connecting long board 91, and contacts are arranged inside each contact hole, and the holders 6 used have different specifications, and different specifications The number or position of the contact rods 620 on the side wall of the upper pressure head 61 of the holder 6 is different. When the contact rods 620 extend into the contact holes and conduct with the contacts, the conduction signal is transmitted to the control system, and the control system then The specifications of the currently used gripper 6 can be judged through different trigger signals, and the specifications of the current fabric sample 8 can be obtained according to the corresponding relationship, so that it is more convenient to carry out the air permeability test. In some preferred embodiments, there are at least two groups of gas delivery units 3 , and at least two groups of gas delivery units 3 communicate with the fan 2 and the air chamber 4 respectively. In actual work, the gas delivery units 3 are arranged side by side, and the opening or closing of the solenoid valve 32 in the gas delivery unit 3 can be controlled by the control system, so that different delivery pipes 31 can be selected for communication according to needs, so as to realize a variety of different flow rates. In the test experiment, the applicability of the fabric air permeability tester of the present invention is stronger.

Please refer to FIG. 3 , as a preferred embodiment of the present invention, the holder 6 further includes a rubber washer 68 , and the rubber washer 68 is arranged on the lower end surface of the sampling head 65 . The setting of the rubber gasket 68 can further ensure the tightness between the sampling head 65 and the outer edge of the fabric sample 8, preventing gas leakage from affecting the accuracy of the test data. In a preferred embodiment, in order to ensure good sealing performance, a rubber pad 10 is also provided between the air chamber 4 and the air-perforated orifice plate 5, and the air chamber 4, the air holes of the air-permeable orifice plate 5 and the pressure sample head 65 The center bore is aligned up and down.

Please refer to Fig. 1 and Fig. 3, as a kind of preferred embodiment of the present invention, described clamper 6 also comprises pipe joint 69, and one end of described pipe joint 69 communicates with the central inner hole of sampling head 65, and pipe The other end of the connector 69 is connected to the differential pressure gauge 7 . The arrangement of the pipe joint 69 facilitates the communication between the differential pressure gauge 7 and the central inner hole of the pressure sample head 65, and the connection efficiency is high, and the butt joint sealing performance is good.

In the preferred embodiment shown in Figure 3, the upper end surface of the air cavity 4 is also provided with an annular accommodation groove, the support net 11 is arranged in the annular accommodation groove, and the inside of the air cavity 4 is also provided with The filter screen 12, the gas in the air cavity 4 enters the delivery pipe 31 through the filter screen 12. The setting of the support net 11 can be used to support the fabric sample 8 from below when the air holes of the air-perforated plate 5 are large, so as to prevent the fabric sample 8 from being damaged by the negative pressure of the fan 2 during the test process. 8 Large deformation occurs, which affects the accuracy of the test results.

It should be noted that although the foregoing embodiments have been described herein, the scope of protection of the present invention is not limited thereby. Therefore, based on the innovative concept of the present invention, the changes and modifications made to the embodiments described herein, or the equivalent structure or equivalent process conversion made by using the description of the present invention and the contents of the accompanying drawings, directly or indirectly apply the above technical solutions In other relevant technical fields, all are included in the scope of protection of the patent of the present invention.

Claims (10)

1. A fabric air permeability tester, characterized in that the tester comprises a frame, a blower fan, a gas delivery unit, an air chamber, a venting orifice, a holder and a differential pressure gauge, and the fan passes through the gas delivery unit It communicates with the air cavity, and the gas delivery unit includes a delivery pipeline, a solenoid valve and a flow meter. One end of the delivery pipeline communicates with the fan, and the other end communicates with the air cavity. The solenoid valve is arranged on the delivery pipeline, and the flow meter Set on the conveying pipeline between the solenoid valve and the air chamber, the air chamber is fixed on the frame, the ventilating orifice is arranged directly above the air chamber, and the holder is arranged directly above the ventilating orifice , there is a gap for placing the fabric sample between the holder and the air-perforated plate, the holder is used to press the fabric sample on the air-perforated plate, and the differential pressure gauge communicates with the air cavity and the holder respectively Chamber, the differential pressure gauge is used to measure the air pressure difference between the upper surface and the lower surface of the fabric sample. 2. The fabric air permeability tester according to claim 1, wherein the holder comprises an upper pressure head, a gland, a guide shaft, a compression spring, a pressure sample head, a pressure plate and a blocking plate, and the upper Both the pressure head and the pressure plate are hollowly sleeved outside the pressure head. The pressure plate is located above the upper pressure head. The guide shaft is evenly arranged outside the pressure head. One end of the guide shaft is fixed with the pressure head, and the other end is empty. In the shaft hole of the upper pressing head, the guide shaft can slide along the shaft hole, the pressure spring is sleeved outside the guiding shaft, and the blocking plate is fixed on the upper end of the upper pressing head. 3. The fabric air permeability tester according to claim 2, characterized in that, the tester also includes a clamping and lifting mechanism, and the clamping and lifting mechanism includes a connecting long plate, a swing arm, a base, and a gas spring , an electromagnet and a limit rod, the connecting long plate is arranged on the swing arm, one end of the connecting long plate is fixed with the holder, the swing arm is hinged and fixed to the base, and the swing arm can be hinged around its hinge with the base One end of the gas spring is connected to the frame, the other end is connected to the swing arm, the limit rod is connected to the electromagnet, and the limit rod is inserted into or moved out of the limit position on the swing arm under the drive of the electromagnet. groove. 4. The fabric air permeability tester according to claim 3, wherein the holder also includes a buckle and a positioning pin, the buckle is arranged on one end of the upper pressing head, and the positioning pin is arranged on the On the side wall of the upper pressing head, a positioning hole is opened on the connecting long plate, the positioning hole is adapted to the positioning pin, and the connecting long plate is connected with the upper pressing head through a buckle. 5. The fabric air permeability tester according to claim 3, wherein at least two contact holes are provided on the side of the connecting long plate facing the upper indenter, and the side wall of the upper indenter is provided with The contact rod can extend into the contact hole to contact conduction. 6 . The fabric air permeability tester according to claim 2 , wherein the holder further comprises a rubber washer, and the rubber washer is arranged on the lower end surface of the sampling head. 6 . 7. The fabric air permeability tester according to claim 2, wherein the holder also includes a pipe joint, one end of the pipe joint communicates with the central inner hole of the pressure sample head, and the other end of the pipe joint One end is connected to the differential pressure gauge. 8 . The fabric air permeability tester according to claim 1 , wherein there are at least two groups of the gas delivery units, and at least two groups of the gas delivery units are respectively connected to the fan and the air chamber. 9. The fabric air permeability tester according to claim 1, characterized in that, a rubber pad is also provided between the air chamber and the air-permeable orifice plate, the air hole of the air chamber, the air-permeable orifice plate and the pressure sample head The center bore is aligned up and down. 10. The fabric air permeability tester according to claim 1, characterized in that, the upper end surface of the air cavity is also provided with an annular accommodation groove, and a support net is arranged in the annular accommodation groove, and the air There is also a filter screen inside the cavity, and the gas in the air cavity enters the delivery pipeline through the filter screen.