A portable low-frequency noise test device for weak electrical signals

Abstract

The invention relates to the technical field of low-frequency noise measuring equipment, and discloses a portable low-frequency noise testing equipment for weak electric signals, comprising a shielding box, wherein the shielding box is composed of a box body and a cover body, wherein the box body and the cover body are both composed of an outer plate a and an inner plate b, a sandwich space is formed between the outer plate a and the inner plate b, and are connected and reinforced by a plurality of reinforcing columns, and the sandwich space of the box body is connected with the sandwich space of the cover body when the box body and the cover body are combined; a handle assembly is fixedly connected to the top of the cover body, an exhaust mechanism is arranged inside the handle assembly, the exhaust mechanism is connected with the sandwich space of the cover body, and the exhaust mechanism is used for exhausting gas in the sandwich space of the box body and the cover body; the box body and the cover body of the invention are both composed of an outer plate a and an inner plate b, so that the box body and the cover body form a sandwich space, and the sandwich space of the box body and the cover body can form a vacuum layer through the exhaust mechanism, and the vacuum layer can have a good isolation effect on low-frequency noise.

Description

Technical Field

[0001] The invention relates to the technical field of low-frequency noise measuring equipment, and more specifically to a portable low-frequency noise testing equipment for weak electric signals. Background Art

[0002] The low-frequency noise test equipment for weak electrical signals is usually a comprehensive test device that integrates high-precision sensors, signal conditioning circuits, data acquisition and processing systems, and user interfaces. Accurate measurement and analysis of weak electrical signals are crucial. These signals are often submerged in complex background noise, especially low-frequency noise. Since its frequency is close to or lower than the signal itself, signal extraction and noise separation become a very challenging task. Existing technologies such as Chinese patents (CN109212336A) disclose "a portable low-frequency noise test method for weak electrical signals" including a shielded room, an anti-vibration table, a shielding box, a bias circuit, an amplifier circuit, a data acquisition module, and a data processing module. The test process is as follows: the sample is placed in a low-noise bias circuit and placed in a double-layer shielding unit of a molybdenum box and a copper box; the electrical noise signal of the sample to be tested is excited by applying a bias voltage; the noise signal is amplified by a DC-powered low-noise amplifier, and then the data acquisition module and data processing module based on the USB interface are used to complete the storage and analysis of the time series and power spectrum data in a laptop computer;

[0003] In order to avoid interference from background noise during the test, various measures are taken, such as setting up a shielded room / shielded box, adding filtering circuits to the circuit, using anti-interference equipment (phase-locked amplifier), etc. Through the synergistic effect of various measures, accurate low-frequency noise testing of weak electrical signals is completed.

[0004] The shielding box of the existing test equipment still has room for improvement. Since the shielding box is used to place the sample to be tested to prevent interference from external noise and electromagnetic fields, thicker high-conductivity materials are usually used. However, this makes the device heavy and difficult to carry. In addition, the isolation effect between the shielding box and the cover is relatively weak, which affects the low-frequency noise isolation effect. Summary of the invention

[0005] In order to overcome the above defects of the prior art, the present invention provides a portable low-frequency noise testing device for weak electrical signals to solve the problems that the traditional device in the above background technology is not easy to carry and the low-frequency noise isolation effect at the opening of the shielding box is weak.

[0006] The present invention provides the following technical solution: A portable low-frequency noise test device for weak electrical signals, comprising a shielding box, the shielding box is composed of a box body and a cover body, the box body and the cover body are both composed of an outer plate a and an inner plate b, a sandwich space is formed between the outer plate a and the inner plate b, and is connected and reinforced by a plurality of reinforcing columns, and the sandwich space of the box body is connected with the sandwich space of the cover body when the box body and the cover body are in a combined state;

[0007] The top of the cover is fixedly connected with a handle assembly, and an exhaust mechanism is arranged inside the handle assembly. The exhaust mechanism is connected to the interlayer space of the cover, and the exhaust mechanism is used to exhaust the gas in the interlayer space of the box body and the cover;

[0008] A sealing gasket frame is fixedly connected to the bottom of the cover body, and locking components are installed on both sides of the cover body. The locking components are used to assemble and fix the box body and the cover body. The exhaust mechanism and the locking components cooperate to lift the box body to press the sealing gasket frame.

[0009] Furthermore, the inner walls of the box body and the cover are provided with sound-proof rubber pads, and the inner walls of the interlayer space of the box body and the cover are painted with sound-proof paint, which includes but is not limited to: polyester fiber sound-proof paint, silicone sound-proof paint, and mineral wool sound-proof paint.

[0010] Furthermore, the sealing gasket frame includes a main frame body, an outer sealing gasket and an inner sealing gasket are fixedly connected to the bottom of the main frame body, the main frame body is made of aluminum material, and a plurality of through holes are opened at the top of the main frame body in the gap between the outer sealing gasket and the inner sealing gasket, and the through holes are used to connect the interlayer space of the box body and the cover body.

[0011] Furthermore, the locking assembly includes a negative pressure contraction assembly, a U-shaped frame, a fixed shaft, a buckle plate, and a groove block. The negative pressure contraction assembly is fixedly connected to the side wall of the cover body, the negative pressure contraction assembly is connected to the interlayer space of the cover body, the groove block is fixedly connected to the side wall of the box body, rail grooves c are provided on both sides of the sealing gasket frame, the U-shaped frame is slidably sleeved in the rail groove c, the bottom end of the negative pressure contraction assembly is fixedly connected to the top of the U-shaped frame, the fixed shaft is fixedly connected to the inner wall of the U-shaped frame, the buckle plate is rotatably sleeved on the side wall of the fixed shaft, the side wall of the buckle plate is transmission connected to the inner wall of the U-shaped frame along the axis of the fixed shaft through a torsion spring, the buckle plate fits with the groove block, and the side wall is provided with a protrusion at the bottom of the groove rail c, and the top of the protrusion is transmission connected to the bottom of the groove rail c through a spring.

[0012] Furthermore, the spring includes a cylinder shell, a piston rod is slidably sleeved inside the cylinder shell, the bottom end of the piston rod extends to the bottom of the cylinder shell and is connected to the U-shaped frame, the inside of the cylinder shell is connected to the interlayer space of the cover body through a connecting pipe, and a positioning ring is provided on the inner wall of the cylinder shell at the top of the piston rod to limit the upward movement distance of the piston rod.

[0013] Furthermore, the reinforcement column includes a main column, and an active noise reduction mechanism is arranged inside the main column. The active noise reduction mechanism is composed of: a shell, a microphone, a noise reduction processor, a speaker and a power supply system. The microphone is used to capture the surrounding noise signals, and the noise reduction processor is used to analyze and process the noise signals captured by the microphone, calculate a reverse sound wave that is opposite to the noise waveform and has the same amplitude, and send it to the speaker. The speaker is used to release the reverse sound wave to offset the noise sound wave, thereby achieving an active noise reduction effect.

[0014] Furthermore, the handle assembly includes a fixed shell, knobs are rotatably sleeved on both sides of the fixed shell, and hand pull rings are fixedly connected to the side walls of the two knobs. A rotation transmission assembly, a turntable assembly, and a ventilation valve are arranged inside the fixed shell. The turntable assembly is fixedly connected to the inner wall of the fixed shell, and the knob is transmission-connected to the turntable assembly through the rotation transmission assembly. The ventilation valve penetrates into the interlayer space of the cover body from the top of the cover body, and the turntable assembly is used to trigger the opening and closing of the ventilation valve.

[0015] Furthermore, the rotary transmission assembly includes a cross bar, a longitudinal bar and two mutually meshing bevel gears, the two bevel gears are respectively fixedly connected to the side walls of the cross bar and the longitudinal bar, the side wall of the longitudinal bar is rotatably sleeved with a fixed block, the fixed block is fixedly connected to the inner wall of the fixed shell, one end of the cross bar is fixedly connected to the knob, and the bottom end of the longitudinal bar is fixedly connected to the turntable assembly.

[0016] Furthermore, the vent valve includes a sleeve, which passes through the interlayer from the top of the cover body, and a center column is slidably sleeved on the inner cavity of the sleeve. A vent hole is opened on the top of the sleeve and passes through the bottom. The side wall of the center column is fixedly connected to a valve plate, and the top of the center column is fixedly connected to a lifting slider, which is docked with the turntable assembly.

[0017] Furthermore, the turntable assembly includes a main disk body, a semi-annular block is fixedly connected to the bottom of the main disk body, the bottom of the semi-annular block is set as a slope, an arc-shaped slide groove is opened at the bottom of the semi-annular block, and the lifting slider is slidably sleeved in the arc-shaped slide groove.

[0018] Technical effects and advantages of the present invention:

[0019] The box body and the cover body of the present invention are both formed by an outer plate a and an inner plate b, so that the box body and the cover body form a sandwich space, and the vacuum mechanism can form a vacuum layer in the sandwich space between the box body and the cover body, and the vacuum layer can have a good isolation effect on low-frequency noise, and the setting of the sandwich space is the same as the traditional solid structure, which can greatly reduce the weight, thereby making it more convenient to carry;

[0020] The sealing degree of the gap between the box body and the cover body can be improved by setting the sealing gasket frame and the locking assembly. On the one hand, the low-frequency noise isolation effect at the gap is improved, and on the other hand, air is prevented from entering the interlayer space through the joint between the box body and the cover body to damage the vacuum insulation layer;

[0021] On the basis of the above, the lock assembly can be linked with the exhaust mechanism through the structural setting. When the exhaust mechanism is running, it can drive the lock assembly to tighten the box body and the cover body, so that the tightness of the connection between the box body and the cover body is improved, and the sealing degree of the joint between the box body and the cover body is increased;

[0022] The outer plate a and the inner plate b of the box body and the cover body are connected by reinforcing columns to improve the structural strength. The structural setting of the reinforcing columns also plays an active noise reduction effect, further improving the low-frequency noise isolation effect of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 It is an exploded schematic diagram of the overall structure of the present invention;

[0025] Figure 3 For the present invention Figure 1 Schematic diagram of the internal structure of the handlebar assembly;

[0026] Figure 4 For the present invention Figure 2 Schematic diagram of the sealing gasket frame structure;

[0027] Figure 5 For the present invention Figure 1 A schematic diagram of the lock assembly structure;

[0028] Figure 6 For the present invention Figure 5 A schematic diagram of the cross-sectional structure of the negative pressure contraction component;

[0029] Figure 7 For the present invention Figure 2 Schematic diagram of the reinforced column structure;

[0030] Figure 8 For the present invention Figure 1 A schematic diagram of the cross-sectional structure of the handlebar assembly;

[0031] Fig. 9 For the present invention Figure 8 Schematic diagram of the rotating transmission assembly, turntable assembly, and ventilation valve structure.

[0032] The accompanying drawings are marked as follows: 1, box body; 2, cover body; 3, reinforcement column; 4, sealing gasket frame; 5, handle assembly; 6, air extraction mechanism; 7, lock assembly; 41, main frame; 42, outer sealing gasket; 43, inner sealing gasket; 71, negative pressure contraction assembly; 72, U-shaped frame; 73, fixed shaft; 74, buckle plate; 75, groove block; 76, torsion spring; 77, spring; 771, cylinder shell; 772, piston rod; 773, connecting pipe; 774. positioning ring; 31. main column; 32. active noise reduction mechanism; 51. fixed shell; 52. knob; 53. hand pull ring; 54. rotary transmission assembly; 55. turntable assembly; 56. vent valve; 541. cross bar; 542. longitudinal bar; 543. fixing block; 551. main disk body; 552. semi-annular block; 561. sleeve; 562. valve plate; 563. center column; 564. lifting slider; 565. vent hole. DETAILED DESCRIPTION

[0033] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0034] Reference Figure 1-Figure 3 The present invention provides a portable low-frequency noise test device for weak electrical signals, including a shielding box, which is composed of a box body 1 and a cover body 2. The box body 1 and the cover body 2 are both composed of an outer plate a and an inner plate b. A sandwich space is formed between the outer plate a and the inner plate b, and is connected and reinforced by a plurality of reinforcing columns 3. When the box body 1 and the cover body 2 are in a combined state, the sandwich space of the box body 1 is connected to the sandwich space of the cover body 2; a handle assembly 5 is fixedly connected to the top of the cover body 2, and an exhaust mechanism 6 is arranged inside the handle assembly 5. The exhaust mechanism 6 is connected to the sandwich space of the cover body 2, and the exhaust mechanism 6 is used to exhaust the gas in the sandwich space of the box body 1 and the cover body 2; a sealing gasket frame 4 is fixedly connected to the bottom of the cover body 2, and locking components 7 are installed on both sides of the cover body 2. The locking components 7 are used for combining and fixing the box body 1 and the cover body 2, and the exhaust mechanism 6 and the locking components 7 cooperate to lift the box body 1 to press the sealing gasket frame 4.

[0035] A sandwich space is formed by the structural arrangement of the box body 1 and the cover body 2, and the shielding box is formed close to a vacuum layer under the action of the exhaust mechanism 6. Since low-frequency noise sound waves are transmitted without a medium in the vacuum layer, the shielding box has a good low-frequency noise isolation effect. In addition, the setting of the sandwich space can reduce the weight of the box body 1 and the cover body 2, making it more convenient to carry. The box body 1 and the cover body 2 are combined and fixed by arranging a locking assembly 7, and the gap between the box body 1 and the cover body 2 is filled by the sealing gasket frame 4 to improve the sealing performance, thereby preventing external gas from entering the sandwich space between the box body 1 and the cover body 2. When the exhaust mechanism 6 is running, the locking assembly 7 can also form a lifting effect on the box body 1 under the action of negative pressure, so that the box body 1 presses the sealing gasket frame 4, so that the sealing performance between the box body 1 and the cover body 2 is further improved.

[0036] Reference Figure 2 The inner walls of the box body 1 and the cover body 2 are provided with sound insulation rubber pads, and the inner walls of the interlayer space of the box body 1 and the cover body 2 are painted with sound insulation paint, and the sound insulation paint includes but is not limited to: polyester fiber sound insulation paint, silicone sound insulation paint, and mineral wool sound insulation paint.

[0037] The shielding box has multi-level and multi-type sound insulation effects, making it have a better shielding effect on low-frequency noise.

[0038] Reference Figure 4 The sealing gasket frame 4 includes a main frame body 41, an outer sealing gasket 42 and an inner sealing gasket 43 are fixedly connected to the bottom of the main frame body 41, the main frame body 41 is made of aluminum material, and a plurality of through holes are opened at the top of the main frame body 41 at the gap between the outer sealing gasket 42 and the inner sealing gasket 43, and the through holes are used to connect the interlayer space of the box body 1 and the cover body 2.

[0039] When the box body 1 and the cover body 2 are combined, the outer sealing gasket 42 and the inner sealing gasket 43 are respectively pressed against the outer plate a and the inner plate b of the box body 1 to achieve a sealing effect. The material characteristics of the main frame 41 can achieve a good shielding effect on both low-frequency noise and electromagnetic interference, thereby improving the shielding performance of the gap between the box body 1 and the cover body 2.

[0040] Reference Figure 5 The locking assembly 7 includes a negative pressure contraction assembly 71, a U-shaped frame 72, a fixed shaft 73, a buckle plate 74, and a groove block 75. The negative pressure contraction assembly 71 is fixedly connected to the side wall of the cover body 2, and the negative pressure contraction assembly 71 is connected to the interlayer space of the cover body 2. The groove block 75 is fixedly connected to the side wall of the box body 1. Rail grooves c are provided on both sides of the sealing gasket frame 4. The U-shaped frame 72 is slidably sleeved in the rail groove c. The bottom end of the negative pressure contraction assembly 71 is fixedly connected to the top of the U-shaped frame 72. The fixed shaft 73 is fixedly connected to the inner wall of the U-shaped frame 72. The buckle plate 74 is rotatably sleeved on the side wall of the fixed shaft 73. The side wall of the buckle plate 74 is transmission-connected to the inner wall of the U-shaped frame 72 along the axis of the fixed shaft 73 through a torsion spring 76. The buckle plate 74 fits with the groove block 75. A protrusion is provided on the side wall at the bottom of the groove rail c, and the top of the protrusion is transmission-connected to the bottom of the groove rail c through a spring 77.

[0041] When the box body 1 and the cover body 2 are combined, the torsion force of the torsion spring 76 drives the buckle plate 74 to flip and buckle on the groove block 75, thereby achieving the combined connection effect of the locking assembly 7. When the vacuum mechanism 6 is operating to pump air, since the interlayer space of the cover body 2 is connected to the negative pressure contraction assembly 71, negative pressure is formed inside the negative pressure contraction assembly 71 for contraction. The negative pressure contraction assembly 71 drives the U-shaped frame 72 to move upward so that the buckle plate 74 hooks the groove block 75 upward. At this time, the box body 1 applies pressure to the top under the action of the groove block 75 to press the sealing gasket frame 4, thereby further improving the sealing degree of the gap between the box body 1 and the cover body 2. When the pressure in the interlayer space inside the box body 1 and the cover body 2 returns to normal, the position of the U-shaped frame 72 is automatically restored under the influence of the elastic force of the spring 77.

[0042] Reference Figure 6 The spring 77 includes a cylinder shell 771, and a piston rod 772 is slidably sleeved inside the cylinder shell 771. The bottom end of the piston rod 772 extends to the bottom of the cylinder shell 771 and is connected to the U-shaped frame 72. The inside of the cylinder shell 771 is connected to the interlayer space of the cover body 2 through a connecting pipe 773. The inner wall of the cylinder shell 771 is located at the top of the piston rod 772 and is provided with a positioning ring 774 for limiting the upward movement distance of the piston rod 772.

[0043] When the gas inside the cover body 2 is extracted, the gas inside the cylinder shell 771 is discharged due to the connection effect of the connecting pipe 773. At this time, negative pressure is formed in the space inside the cylinder shell 771 at the top of the piston rod 772, causing the piston rod 772 to move upward, achieving a contraction effect.

[0044] Reference Figure 7 The reinforcement column 3 includes a main column 31, and an active noise reduction mechanism 32 is arranged inside the main column 31. The active noise reduction mechanism 32 is composed of: a shell, a microphone, a noise reduction processor, a speaker and a power supply system. The microphone is used to capture the surrounding noise signals. The noise reduction processor is used to analyze and process the noise signals captured by the microphone, calculate a reverse sound wave that is opposite to the noise waveform and has the same amplitude, and send it to the speaker. The speaker is used to release the reverse sound wave to offset the noise sound wave to achieve the active noise reduction effect.

[0045] Since the reinforcing column 3 not only provides structural strength for the box body 1 and the cover body 2, but also provides a propagation medium for low-frequency noise, the vacuum isolation effect of low-frequency noise is reduced, and active noise reduction is performed by setting the main column 31, thereby improving the performance of the shielding box.

[0046] Reference Figure 8The handle assembly 5 includes a fixed shell 51, and knobs 52 are rotatably sleeved on both sides of the fixed shell 51. Hand pull rings 53 are fixedly connected to the side walls of the two knobs 52. A rotation transmission assembly 54, a turntable assembly 55, and a vent valve 56 are arranged inside the fixed shell 51. The turntable assembly 55 is fixedly connected to the inner wall of the fixed shell 51. The knob 52 is transmission-connected to the turntable assembly 55 through the rotation transmission assembly 54. The vent valve 56 penetrates from the top of the cover body 2 into the interlayer space of the cover body 2, and the turntable assembly 55 is used to trigger the opening and closing of the vent valve 56.

[0047] When a negative pressure vacuum is formed in the interlayer space between the box body 1 and the cover body 2, the connection between the box body 1 and the cover body 2 can be reinforced under the influence of atmospheric pressure, which makes it difficult to separate the box body 1 and the cover body 2. By turning the hand pull ring 53 to drive the knob 52 to rotate, the turntable assembly 55 is rotated under the transmission effect of the rotating transmission assembly 54 to trigger the vent valve 56 to open. At this time, external gas can enter the interlayer space to balance the pressure in the interlayer space.

[0048] Reference Fig. 9 The rotating transmission assembly 54 includes a cross bar 541, a longitudinal bar 542 and two mutually meshing bevel gears. The two bevel gears are fixedly connected to the side walls of the cross bar 541 and the longitudinal bar 542 respectively. A fixed block 543 is rotatably sleeved on the side wall of the longitudinal bar 542. The fixed block 543 is fixedly connected to the inner wall of the fixed shell 51. One end of the cross bar 541 is fixedly connected to the knob 52, and the bottom end of the longitudinal bar 542 is fixedly connected to the turntable assembly 55.

[0049] Under the meshing action of the two bevel gears, when the knob 52 is turned, the cross bar 541 can drive the longitudinal bar 542 to rotate, thereby rotating the main disk body 551 to achieve the rotation transmission effect of the rotation transmission assembly 54.

[0050] Reference Fig. 9 The vent valve 56 includes a sleeve 561, which penetrates into the interlayer from the top of the cover body 2. A center column 563 is slidably sleeved on the inner cavity of the sleeve 561. A vent hole 565 is opened on the top of the sleeve 561 and penetrates to the bottom. A valve plate 562 is fixedly connected to the side wall of the center column 563. A lifting slider 564 is fixedly connected to the top of the center column 563, and the lifting slider 564 is docked with the turntable assembly 55.

[0051] The top of the sleeve 561 is sealed with a valve plate 562 to close the vent hole 565. At this time, external gas cannot flow into the interlayer of the cover body 2 through the vent hole 565. The pressure difference between the inside and outside of the interlayer space set by this structure will not cause the turntable assembly 55 to open passively.

[0052] Reference Fig. 9The turntable assembly 55 includes a main disk body 551, a semi-annular block 552 is fixedly connected to the bottom of the main disk body 551, the bottom of the semi-annular block 552 is set as a slope, and an arc-shaped slide groove is opened at the bottom of the semi-annular block 552, and the lifting slider 564 is slidably sleeved in the arc-shaped slide groove.

[0053] When the turntable assembly 55 rotates, the relative position of the semi-annular block 552 changes, and the lifting slider 564 slides in the arc-shaped slide groove. Affected by the bottom slope of the semi-annular block 552, the semi-annular block 552 will drive the lifting slider 564 to change in height. When the height of the lifting slider 564 increases, it drives the valve plate 562 to move upward. At this time, a gap is generated between the valve plate 562 and the sleeve 561, and external gas enters the interlayer space through the vent 565, thereby achieving a pressure balance effect.

[0054] The above shows and describes the basic principles, main features and advantages of the present invention. The present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A portable low-frequency noise test device for weak electrical signals, comprising a shielding box, characterized in that: The shielding box is composed of a box body (1) and a cover body (2); the box body (1) and the cover body (2) are both composed of an outer plate a and an inner plate b; a sandwich space is formed between the outer plate a and the inner plate b, and is connected and reinforced by a plurality of reinforcing columns (3); when the box body (1) and the cover body (2) are in a combined state, the sandwich space of the box body (1) is connected to the sandwich space of the cover body (2); The top of the cover body (2) is fixedly connected to a handle assembly (5), and an exhaust mechanism (6) is arranged inside the handle assembly (5). The exhaust mechanism (6) is connected to the interlayer space of the cover body (2). The exhaust mechanism (6) is used to exhaust the gas in the interlayer space between the box body (1) and the cover body (2), thereby isolating low-frequency noise through the vacuum layer; The bottom of the cover body (2) is fixedly connected to a sealing gasket frame (4), and locking components (7) are installed on both sides of the cover body (2). The locking components (7) are used to assemble and fix the box body (1) and the cover body (2). When the air extraction mechanism (6) is in operation, the air extraction mechanism (6) and the locking components (7) cooperate to lift the box body (1) and press the sealing gasket frame (4). The reinforcement column (3) comprises a main column (31), an active noise reduction mechanism (32) is arranged inside the main column (31), and the active noise reduction mechanism (32) is composed of: a housing, a microphone, a noise reduction processor, a speaker, and a power supply system. The microphone is used to capture surrounding noise signals. The noise reduction processor is used to analyze and process the noise signals captured by the microphone, calculate a reverse sound wave that is opposite to the noise waveform and has the same amplitude, and send it to the speaker. The speaker is used to release the reverse sound wave to offset the noise sound wave, thereby performing active noise reduction. The handle assembly (5) comprises a fixed shell (51), both sides of the fixed shell (51) are rotatably sleeved with knobs (52), the side walls of the two knobs (52) are fixedly connected with hand pull rings (53), the fixed shell (51) is provided with a rotation transmission assembly (54), a turntable assembly (55), and a vent valve (56), the turntable assembly (55) is fixedly connected to the inner wall of the fixed shell (51), the knob (52) is transmission-connected to the turntable assembly (55) via the rotation transmission assembly (54), the vent valve (56) penetrates from the top of the cover body (2) into the interlayer space of the cover body (2), and the turntable assembly (55) is used to trigger the opening and closing of the vent valve (56); The locking assembly (7) comprises a negative pressure contraction assembly (71), a U-shaped frame (72), a fixed shaft (73), a buckle plate (74), and a groove block (75); the negative pressure contraction assembly (71) is fixedly connected to the side wall of the cover body (2); the negative pressure contraction assembly (71) is connected to the interlayer space of the cover body (2); the groove block (75) is fixedly connected to the side wall of the box body (1); groove rails c are provided on both sides of the sealing gasket frame (4); the U-shaped frame (72) is slidably sleeved in the groove rails c; the negative pressure contraction assembly The bottom end of (71) is fixedly connected to the top of the U-shaped frame (72), the fixed shaft (73) is fixedly connected to the inner wall of the U-shaped frame (72), the buckle plate (74) is rotatably sleeved on the side wall of the fixed shaft (73), the side wall of the buckle plate (74) is transmission-connected to the inner wall of the U-shaped frame (72) along the axis of the fixed shaft (73) through a torsion spring (76), the buckle plate (74) is matched with the groove block (75), and the side wall is provided with a protrusion at the bottom of the groove rail c, and the top of the protrusion is transmission-connected to the bottom of the groove rail c through a spring (77); The negative pressure contraction component (71) comprises a cylinder shell (771), a piston rod (772) being slidably sleeved inside the cylinder shell (771), the bottom end of the piston rod (772) extending to the bottom of the cylinder shell (771) and connected to the U-shaped frame (72), the inside of the cylinder shell (771) being connected to the interlayer space of the cover body (2) via a connecting pipe (773), and a positioning ring (774) for limiting the upward movement distance of the piston rod (772) is provided on the inner wall of the cylinder shell (771) at the top of the piston rod (772); The rotary transmission assembly (54) comprises a crossbar (541), a longitudinal rod (542) and two mutually meshing bevel gears, the two bevel gears being fixedly connected to the side walls of the crossbar (541) and the longitudinal rod (542) respectively, a fixing block (543) being rotatably sleeved on the side wall of the longitudinal rod (542), the fixing block (543) being fixedly connected to the inner wall of the fixed shell (51), one end of the crossbar (541) being fixedly connected to the knob (52), and the bottom end of the longitudinal rod (542) being fixedly connected to the turntable assembly (55); The vent valve (56) comprises a sleeve (561), the sleeve (561) penetrates into the interlayer from the top of the cover body (2), a central column (563) is slidably sleeved in the inner cavity of the sleeve (561), a vent hole (565) is opened at the top of the sleeve (561) and penetrates to the bottom, a valve plate (562) is fixedly connected to the side wall of the central column (563), a lifting slider (564) is fixedly connected to the top of the central column (563), and the lifting slider (564) is docked with the turntable assembly (55); The turntable assembly (55) comprises a main disk body (551), a semi-annular block (552) being fixedly connected to the bottom of the main disk body (551), the bottom of the semi-annular block (552) being arranged as a slope, an arc-shaped slide groove being provided at the bottom of the semi-annular block (552), and the lifting slider (564) being slidably sleeved in the arc-shaped slide groove.

2. A portable low-frequency noise test device for weak electrical signals according to claim 1, characterized in that: The inner walls of the box body (1) and the cover body (2) are provided with sound insulation rubber pads, and the inner walls of the interlayer space of the box body (1) and the cover body (2) are painted with sound insulation paint, wherein the sound insulation paint includes but is not limited to: polyester fiber sound insulation paint, silicone sound insulation paint, and mineral wool sound insulation paint.

3. A portable low-frequency noise test device for weak electrical signals according to claim 2, characterized in that: The sealing gasket frame (4) comprises a main frame body (41), the bottom of the main frame body (41) is fixedly connected with an outer sealing gasket (42) and an inner sealing gasket (43), the main frame body (41) is made of aluminum material, and the top of the main frame body (41) is provided with a plurality of through holes located in the gap between the outer sealing gasket (42) and the inner sealing gasket (43), wherein the through holes are used to connect the interlayer space of the box body (1) and the cover body (2).

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