Variable parameter piston sounder

Abstract

The application relates to a variable-parameter piston sound generator, which is provided with a piston structure with a first piston and a second piston. Since the piston structure has two sets of piston systems, and the large and small pistons are convenient to switch, the technical advantages of a large sound pressure range and a wide frequency range are realized, the disadvantages of the prior art that the piston cross-section size and the cavity size are fixed due to the use of a single piston matched with one or more fixed cavities are solved, the cavity volume of the body is changed through the variable-cavity piston fixedly connected with a driving part, the cavity volume of the body is continuously adjustable, the disadvantages that the output continuity and the use convenience are affected due to the replacement of the cylinder body when the sound pressure output range of the prior art piston sound generator is adjusted are solved, and the technical effects of strong continuous adjustment and convenient use are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sound pressure sensor calibration, in particular to a variable parameter piston sound generator. BACKGROUND

[0002] Infrasound is generally considered to be a sound wave with a frequency lower than 20 Hz. Infrasound is widely used in military, environmental monitoring, medical treatment and industrial production, although it is harmful to humans. The measurement of infrasound is a key problem in the study of infrasound. The piston sound generator is currently considered to be the most suitable method for infrasound microphone calibration. The existing high-precision calibration infrasound piston sound generator mostly uses a single piston and multiple cavities to generate sound pressure signals, which limits the output sound pressure range, output continuity and ease of use. There are also some double-piston variable-cavity piston sound generators, but they still have the disadvantages of narrow output sound pressure range and poor output continuity. Therefore, the present application proposes a variable parameter piston sound generator. SUMMARY

[0003] In order to solve the problems of narrow output sound pressure range and poor output continuity of the traditional piston sound generator, the present application proposes a variable parameter piston sound generator.

[0004] The present application provides a variable parameter piston sound generator, which comprises a sound generating cavity, a piston, a microphone, a piston structure, a laser vibration measurement device, a vibration table and a driving module.

[0005] The sound generating cavity comprises a body, a first annular sheet and a second annular sheet. The body comprises a first end and a second end. The first end is fixedly connected with the first annular sheet, and the second end is fixedly connected with the second annular sheet. The body is an equal-thickness uniform circular tube.

[0006] The microphone is arranged at one end of the piston body close to the first annular sheet.

[0007] The piston structure is fixedly connected with the first annular sheet.

[0008] The laser vibration measurement device is used to measure the displacement of the piston structure.

[0009] The vibration table is connected with the piston structure and used to drive the piston structure to vibrate.

[0010] The driving module is fixedly connected with the variable cavity piston through the second annular sheet.

[0011] Further, a plurality of groups of the gas film generating structures are arranged on the outer circumferential surface of the piston body, and the plurality of groups of the gas film generating structures are uniformly arranged around the central axis of the piston body.

[0012] Further, each group of the gas film generating structures comprises a plurality of communication air holes, an annular air groove, an air sealing ring piece, and a gas filling connector.

[0013] Each of the communication air holes is in communication with the annular air groove.

[0014] The plurality of communication air holes are uniformly arranged around the central axis of the annular air groove.

[0015] The air sealing ring piece is fixedly connected to the piston body.

[0016] The gas filling connector is in communication with the annular air groove through the hole of the air sealing ring piece.

[0017] The gas filling connector is connected with a gas filling device.

[0018] Further, the piston body further comprises a first inner cavity and a second inner cavity.

[0019] The first inner cavity is in communication with the second inner cavity.

[0020] The gas filling connector is arranged on the cavity wall of the second inner cavity.

[0021] Further, the variable-cavity piston further comprises a connecting ring piece and a plurality of driving rods.

[0022] The connecting ring piece is fixedly connected to the variable-cavity piston.

[0023] The connecting ring piece is fixedly connected to each of the driving rods.

[0024] The plurality of driving rods are parallel to each other.

[0025] Each of the driving rods is fixedly connected to the driving module.

[0026] Further, the driving module comprises a support plate, a connecting plate, a connecting mechanism, a motor, and a guide rail; the connecting plate is fixedly connected to each of the driving rods.

[0027] The support plate is arranged on the guide rail.

[0028] The connecting plate and the support plate are connected through the connecting mechanism.

[0029] The motor is connected to the guide rail, and the motor drives the support plate to move along the guide rail. Further, the piston structure comprises a film pressing flange and an elastic film.

[0030] The film pressing flange is fixedly connected to the first annular piece.

[0031] The elastic film is arranged between the film pressing flange and the first annular sheet;

[0032] The film pressing flange is provided with a plurality of fastening nails;

[0033] The central axis of the film pressing flange coincides with the central axis of the body;

[0034] Each of the fastening nails is perpendicular to the central axis of the film pressing flange.

[0035] Further, the piston structure further comprises a first piston and a second piston;

[0036] The vibration table comprises a connecting shaft;

[0037] The first piston is sleeved on the second piston;

[0038] The film pressing flange is sleeved on the first piston;

[0039] The first piston is provided with a film pressing ring plate at one end close to the first annular sheet;

[0040] The second piston is threadedly connected with the connecting shaft through an adjusting nut;

[0041] The first piston is provided with external threads on the outer cylindrical surface at one end close to the connecting shaft.

[0042] Further, the piston structure further comprises a limiting ring, a guide ring and a locking ring;

[0043] The limiting ring is arranged on the first piston and close to the connecting shaft;

[0044] The guide ring is sleeved on the first piston;

[0045] The inner diameter of the guide ring at one end close to the film pressing flange is equal to the outer diameter of the first piston; the inner diameter of the middle part of the guide ring is smaller than the outer diameter of the first piston;

[0046] The guide ring is provided with internal threads;

[0047] The outer periphery of the connecting shaft is provided with external threads;

[0048] The outer periphery of the film pressing flange is provided with external threads;

[0049] The locking ring is provided with internal threads; when the first piston is in a fixed state and the second piston is in a movable state, the film pressing flange is threadedly connected with the locking ring; when the first piston and the second piston are both in a movable state, the connecting shaft is threadedly connected with the locking ring;

[0050] The guide ring is threadedly connected with the first piston.

[0051] The application relates to a variable parameter piston sound generator, which is provided with a piston structure with a first piston and a second piston. Since the piston structure has two sets of piston systems and the large and small pistons are convenient to switch, the technical advantages of a large sound pressure range and a wide frequency range are achieved, the disadvantages of a fixed piston cross-section size and a fixed cavity size caused by the use of a single piston matched with one or more fixed cavities in the existing piston sound generator are solved, the cavity volume of the body is continuously adjustable through the variable cavity piston fixedly connected with the driving component, and the disadvantages of the influence of the output continuity and the use convenience caused by the replacement of the cylinder body during the adjustment of the sound pressure output range in the existing piston sound generator are solved, and the technical effects of strong continuous adjustment and convenient use are achieved. BRIEF DESCRIPTION OF DRAWINGS

[0052] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, make the other features, purposes and advantages of the present application more apparent. The schematic embodiment drawings of the present application and the description thereof are used to explain the present application, and do not constitute an improper limitation on the present application.

[0053] Figure 1 A structural schematic view of a variable parameter piston sound generator provided for an embodiment of the present application.

[0054] Figure 2 A sectional view of a variable cavity piston of a variable parameter piston sound generator provided for an embodiment of the present application.

[0055] Figure 3 A structural schematic view of a driving module of a variable parameter piston sound generator provided for an embodiment of the present application.

[0056] Figure 4 A sectional view of a variable parameter piston structure provided for an embodiment of the present application.

[0057] Figure 5 A sectional view of a variable parameter piston structure provided for another embodiment of the present application.

[0058] Reference signs:

[0059] 100 - sound generating cavity; 110 - body; 111 - first end; 112 - second end; 120 - first annular sheet;

[0060] 130 - second annular sheet; 200 - variable cavity piston; 210 - piston body; 211 - first inner cavity;

[0061] 212 - second inner cavity; 220 - QY type sealing ring; 230 - gas film generating structure; 231 - communication gas hole;

[0062] 232-Annular air groove; 233-Sealing ring; 234-Inflation connector; 240-Connecting ring;

[0063] 250 - Drive rod; 260 - Pressure diaphragm flange; 261 - Fastening pin; 270 - Elastic diaphragm; 280 - First piston;

[0064] 281-Diameter pressure ring plate; 290-Second piston; 291-Limit ring; 292-Guide ring; 293-Locking ring;

[0065] 300 - Microphone; 400 - Piston structure; 500 - Laser vibration measurement device; 600 - Vibration table;

[0066] 610 - Connecting shaft; 611 - Adjusting nut; 700 - Drive module; 710 - Support plate; 720 - Connecting plate;

[0067] 730 - Connecting mechanism; 740 - Motor; 750 - Guide rail; 800 - Support rod. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0069] This application provides a variable-parameter piston sound generator.

[0070] like Figure 1 As shown, in one embodiment of this application, a variable-parameter piston sound generator includes: a sound-generating cavity 100, a variable-cavity piston 200, a microphone 300, a piston structure 400, a laser vibration measuring device 500, a vibration table 600, and a drive module 700.

[0071] The sound-emitting cavity 100 includes a body 110, a first annular plate 120 and a second annular plate 130. The body 110 includes a first end 111 and a second end 112. The first end 111 is fixedly connected to the first annular plate 120 and the second end 112 is fixedly connected to the second annular plate 130. The body 110 is a circular tube with uniform thickness.

[0072] The variable-cavity piston 200 includes a piston body 210, multiple sets of sealing ring structures 220, and multiple sets of gas film generating structures 230. The outer diameter of the piston body 210 is equal to the inner diameter of the body 110 and is disposed within the inner cavity of the body 110. Each set of sealing ring structures 220 is disposed between the piston body 210 and the inner cavity of the body 110, and each set of gas film generating structures 230 is attached to the outer circumferential surface of the piston body 210. The piston body 210 and the inner cavity of the body 110 are in clearance fit.

[0073] The microphone 300 is arranged on the piston body 210 close to one end of the first annular sheet 120.

[0074] The piston structure 400 is fixedly connected to the first annular sheet 120.

[0075] The laser vibration measuring device 500 is used to measure the displacement of the piston structure 400.

[0076] The vibration table 600 is connected to the piston structure 400 and used to drive the piston structure 400 to vibrate.

[0077] The driving module 700 is fixedly connected to the variable-cavity piston 200 through the second annular sheet 130.

[0078] Specifically, the body 110 of the sound production cavity 100 is an equal-thickness uniform circular tube, and the inner cavity of the equal-thickness uniform circular tube provides a smooth and flat movement path for the variable-cavity piston 200. When the variable-cavity piston 200 slides in the inner cavity of the body 110, the volume between the piston structure 400 and the microphone 300 changes. When the piston structure 400 performs sinusoidal vibration, an acoustic field will be formed in the cavity of the body 110. All dimensions of the cavity are much smaller than the wavelength of the sound wave, and the cavity wall is rigid. The sound pressure range of the sound pressure signal output by the piston sound generator is related to the cavity structure size. Therefore, the change of the cavity structure size can affect the sound pressure range of the sound pressure signal output by the piston sound generator.

[0079] The embodiment relates to a variable-parameter piston sound generator, which is provided with a piston structure 400 having a first piston 280 and a second piston 290. Since the piston structure 400 has two sets of piston systems and the large and small pistons are convenient to switch, the technical advantages of a wide sound pressure range and a wide frequency range are achieved, and the disadvantages of the prior art piston sound generator, i.e., the fixed piston cross-sectional size and cavity size caused by the use of a single piston matched with one or more fixed cavities, are solved. Through the variable-cavity piston 200 fixedly connected to the driving component, the cavity volume of the body 110 is changed, the cavity volume of the body 110 is continuously adjustable, and the disadvantages of the prior art piston sound generator, i.e., the need to replace the cylinder body when adjusting the sound pressure output range, the influence on the output continuity and the use convenience caused by calibration, are solved. The technical effects of strong continuous adjustment and convenient use are achieved.

[0080] As shown in FIG. 1, Figures 1-2 In an embodiment of the present application, each set of sealing ring structure 220 is a QY type sealing ring.

[0081] The embodiment relates to a sealing ring structure 220. The QY type sealing ring is a special sealing ring for a cylinder piston, friction resistance of the QY type sealing ring is smaller than that of an ordinary O type sealing ring, the QY type sealing ring is suitable for being used on a sealing surface needing movement, and the QY type sealing ring effectively solves the problem that, when the sound pressure output range of a piston sound generator is adjusted, the moving variable cavity piston 200 causes the calibration output continuity and the use convenience to be affected.

[0082] As shown in the figure, in an embodiment of the present application, a plurality of groups of gas film generating structures 230 are arranged on the outer circumferential surface of the piston body 210, and the plurality of groups of gas film generating structures 230 are uniformly arranged around the central axis of the piston body 210. Figures 1-2

[0083] The embodiment relates to the gas film generating structure 230. When the variable cavity piston 200 needs to be moved, high-pressure gas is introduced into the gas film generating structure 230, the high-pressure gas forms uniformly distributed gas films between the variable cavity piston 200 and the inner cavity of the body 110 through the gas holes of the gas film generating structure 230. Under the buffering of the gas films, the friction of the variable cavity piston 200 is reduced during the sliding process in the inner cavity of the body 110, and the problem that, when the sound pressure output range of the piston sound generator is adjusted, the moving variable cavity piston 200 causes the calibration output continuity and the use convenience to be affected is effectively solved.

[0084] As shown in the figure, in an embodiment of the present application, each group of gas film generating structures 230 comprises a plurality of communication gas holes 231, an annular gas groove 232, a gas sealing ring piece 233 and a gas filling connector 234. Each communication gas hole 231 is in communication with the annular gas groove 232. The plurality of communication gas holes 231 are uniformly arranged around the central axis of the annular gas groove 232. The gas sealing ring piece 233 is fixedly connected to the piston body 210. The gas filling connector 234 is in communication with the annular gas groove 232 through the hole of the gas sealing ring piece 233. The gas filling connector 234 is connected with a gas filling device. Figures 1-2 The embodiment relates to the gas film generating structure 230. The plurality of communication gas holes 231 are arranged around the central axis of the annular gas groove 232. The uniformity of the gas film between the variable cavity piston 200 and the body 110 is ensured, because the annular gas groove 232 and the plurality of communication gas holes 231 are in communication and the central axis of the unique annular gas groove 232 coincides with the central axis of the body, so the gas pressure of the communication gas holes 231 in the same group is consistent. This also ensures the uniformity of the gas film between the variable cavity piston 200 and the body 110.

[0085] As shown in the figure, in an embodiment of the present application, the piston body 210 further comprises a first inner cavity 211 and a second inner cavity 212. The first inner cavity 211 is in communication with the second inner cavity 212. The gas filling connector 234 is arranged on the cavity wall of the second inner cavity 212.

[0086] Figures 1-2

[0087] ​​​The embodiment relates to the piston body 210. The first inner cavity 211 and the second inner cavity 212 are used to provide sufficient cavities to accommodate pipes. The arrangement ensures that the piston body 210 does not need to move the body 110 during movement. The problem of the piston sound generator moving in the variable cavity piston 200 when adjusting the sound pressure output range is effectively solved, and the calibration output continuity and use convenience are affected.

[0088] As shown in the embodiment of the present application, the variable cavity piston 200 further comprises a connecting ring piece 240 and a plurality of driving rods 250. The connecting ring piece 240 is fixedly connected with the variable cavity piston 200. The connecting ring piece 240 is fixedly connected with each of the driving rods 250. The plurality of driving rods 250 are parallel to each other. Each of the driving rods 250 is fixedly connected with the driving module 700. Figures 1-2 The embodiment relates to the connecting ring piece 240 and the driving rod 250. Since the piston body 210 is provided with the second inner cavity 212, in the actual processing process, in order to reduce the manufacturing difficulty of the piston body 210, the second inner cavity 212 is an open cavity, and the open cavity refers to that the end face of the second cavity close to the second ring piece 130 is a hole. Therefore, the driving rod 250 cannot be arranged between the piston body 210. In order to fix the driving rod 250, the designer introduces the connecting ring piece 240, the connecting ring piece 240 can be fixedly connected with the piston body 210 through the side wall of the piston body 210, and the fixing position required by the driving rod 250 is large and is not conducive to being connected to the side wall of the piston body 210. The connecting ring piece 240 can provide a large fixing position, and the driving rod 250 can be better connected.

[0089] As shown in the embodiment of the present application, the driving module 700 comprises a support plate 710, a connecting plate 720, a connecting mechanism 730, a motor 740 and a guide rail 750. The connecting plate 720 is fixedly connected with each of the driving rods 250. The connecting plate 720 is connected with the support plate 710 through the connecting mechanism 730. The guide rail 750 is a ball screw sliding block mechanism, the support plate 710 is arranged on the sliding block of the guide rail 750, the motor 740 drives the screw rod to rotate, the screw rod drives the sliding block to slide and further drives the driving rod 250 to move.

[0090] Figure 3 The embodiment relates to the driving module 700. The driving module 700 mainly provides power for the movement of the variable cavity piston 200. It is worth mentioning that the connecting mechanism 730 further comprises a support rod 800 and a joint bearing, the joint bearing is sleeved on the support rod 800, and the support rod 800 is fixed to the support plate 710. When the driving rod 250 moves, the driving rod 250 and the support plate 710 can be dithered, and the joint bearing can provide a degree of freedom to couple the dithering.

[0091] As shown in the embodiment of the present application, the driving module 700 comprises a support plate 710, a connecting plate 720, a connecting mechanism 730, a motor 740 and a guide rail 750. The connecting plate 720 is fixedly connected with each of the driving rods 250. The connecting plate 720 is connected with the support plate 710 through the connecting mechanism 730. The guide rail 750 is a ball screw sliding block mechanism, the support plate 710 is arranged on the sliding block of the guide rail 750, the motor 740 drives the screw rod to rotate, the screw rod drives the sliding block to slide and further drives the driving rod 250 to move.

[0092] As shown in the embodiment of the present application, the driving module 700 comprises a support plate 710, a connecting plate 720, a connecting mechanism 730, a motor 740 and a guide rail 750. The connecting plate 720 is fixedly connected with each of the driving rods 250. The connecting plate 720 is connected with the support plate 710 through the connecting mechanism 730. The guide rail 750 is a ball screw sliding block mechanism, the support plate 710 is arranged on the sliding block of the guide rail 750, the motor 740 drives the screw rod to rotate, the screw rod drives the sliding block to slide and further drives the driving rod 250 to move. Figures 4-5 ​As shown, in one embodiment of this application, the piston structure 400 includes a pressure-film flange 260 and an elastic diaphragm 270. The pressure-film flange 260 is fixedly connected to the first annular plate 120. The elastic diaphragm 270 is disposed between the pressure-film flange 260 and the first annular plate 120. The pressure-film flange 260 is provided with a plurality of fastening pins 261. The central axis of the pressure-film flange 260 coincides with the central axis of the body 110. Each fastening pin 261 is perpendicular to the central axis of the pressure-film flange 260.

[0093] This embodiment relates to a piston structure 400. A diaphragm flange 260 limits the position of an elastic diaphragm 270 disposed between the diaphragm flange 260 and the first annular plate 120. This creates a sealed space between the elastic diaphragm 270 and the variable-cavity piston 200, which facilitates the generation of infrasound. A microphone 300 disposed at the end of the piston body 210 near the first annular plate 120 can receive the infrasound.

[0094] like Figures 4-5 As shown, in one embodiment of this application, the piston structure 400 further includes a first piston 280 and a second piston 290. The vibration table 600 includes a connecting shaft 610. The first piston 280 is sleeved on the second piston 290. A pressure flange 260 is sleeved on the first piston 280. A pressure ring plate 281 is provided at one end of the first piston 280 near the first annular plate 120. The second piston 290 is threadedly connected to the connecting shaft 610 by an adjusting nut 611. The outer cylindrical surface of the first piston 280 near the connecting shaft 610 is provided with external threads.

[0095] This embodiment involves a piston structure 400. A first piston 280 is fitted onto a second piston 290. A pressure diaphragm flange 260 is fitted onto the first piston 280. The central axis of the pressure diaphragm flange 260 coincides with the central axis of the body 110. Therefore, the central axes of the first piston 280 and the second piston 290 also coincide with the central axis of the body 110. This facilitates efficient use of the entire space of the body 110 chamber, and according to the sound wave transmission characteristics, the pressure source being located on the central axis of the body 110 can improve the sound generation efficiency of the body 110. The first piston 280 is fitted onto the second piston 290. When the first piston 280 slides along the pressure diaphragm flange 260 or the second piston 290 slides along the first piston 280, the first piston 280 and the second piston 290 can transmit mechanical vibrations to the elastic diaphragm 270, which helps the elastic diaphragm 270 convert sinusoidal vibrations into infrasound waves.

[0096] like Figures 4-5As shown, in one embodiment of this application, the piston structure 400 further includes a limiting ring 291, a guide ring 292, and a locking ring 293. The limiting ring 291 is disposed on the first piston 280 and close to the connecting shaft 610. The guide ring 292 is sleeved on the first piston 280. The inner diameter of the guide ring 292 near the pressure plate flange 260 is equal to the outer diameter of the first piston 280. The inner diameter of the middle portion of the guide ring 292 is smaller than the outer diameter of the first piston 280. The guide ring 292 has an internal thread. The outer circumferential surface of the connecting shaft 610 has an external thread. The outer circumferential surface of the pressure plate flange 260 has an external thread. The locking ring 293 has an internal thread. When the first piston 280 is in a fixed state and the second piston 290 is in a movable state, the pressure plate flange 260 is threadedly connected to the locking ring 293; when both the first piston 280 and the second piston 290 are in a movable state, the connecting shaft 610 is threadedly connected to the locking ring 293. The guide ring 292 is threadedly connected to the first piston 280.

[0097] Specifically, the dual-piston switching steps include: when the second piston 290 needs to move, the connecting shaft 610 drives the large piston back to its initial position, tightens the fastening pin 261 to fix the first piston 280, rotates the locking ring 293 to disengage from the connecting shaft 610, the locking ring 293 is screwed into the pressure diaphragm flange 260 along the guide ring 292 and tightened, rotates the guide ring 292 to disengage from the connecting shaft 610, moves along the first piston 280 until it is completely fixed, the connecting shaft 610 drives the second piston 290 to move until it contacts the elastic diaphragm 270 and applies a certain pre-tightening force, and the connecting shaft 610 drives the second piston 290 to work. When the first piston 280 needs to move, the rotating guide ring 292 moves along the first piston 280 toward the connecting shaft 610 until it is completely fixed. The locking ring 293 is rotated to disengage from the pressure diaphragm flange 260 and moves along the guide ring 292 toward the connecting shaft 610 until it is completely fixed. The fastening pin 261 is rotated to allow relative movement between the first piston 280 and the pressure diaphragm flange 260. The locking ring 293 is threadedly connected to the connecting shaft 610. At this time, the locking ring 293 presses the guide ring 292 against one end of the connecting shaft 610, and the guide ring 292 abuts against the limiting ring 291, which is fixedly connected to the first piston 280. The connecting shaft 610 drives the first piston 280 and the second piston 290 to work together.

[0098] This embodiment relates to a piston structure 400. The piston structure 400 has two piston systems, and the first piston 280 and the second piston 290 can be easily switched. The first piston 280 and the second piston 290, together with the body 110 and the variable cavity piston 200, can realize sound pressure signal output with an ultra-wide frequency range and sound intensity range.

[0099] It is worth mentioning that the elastic membrane 270 is fixed on the inclined surface formed by the outer wedge ring and the inner wedge ring. During assembly, the pressure mold flange presses the outer wedge ring tightly to achieve the tensioning of the elastic membrane 270.

[0100] Any combination of the technical features in the above embodiments can be made, and the method steps are not limited in execution order. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described, however, as long as the combination of the technical features does not exist in contradiction, it shall be considered as within the scope of the present disclosure. The above embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but it shall not be understood as a limitation on the patent scope of the present application. It shall be pointed out that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, which shall be within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A variable parameter piston sounder characterized by, include: The sound-emitting cavity includes a body, a first annular plate, and a second annular plate. The body includes a first end and a second end. The first end is fixedly connected to the first annular plate, and the second end is fixedly connected to the second annular plate. The body is a circular tube. A variable-cavity piston includes a piston body, multiple sets of sealing ring structures, and multiple sets of gas film generating structures. The outer diameter of the piston body is equal to the inner diameter of the main body and is disposed in the inner cavity of the main body. Each set of sealing ring structures is disposed between the piston body and the inner cavity of the main body, and each set of gas film generating structures is attached to the outer circumferential surface of the piston body. A microphone is located at one end of the piston body near the first annular plate; The piston structure is fixedly connected to the first annular plate; A laser vibration measuring device is used to measure the displacement of the piston structure; A vibration table, connected to the piston structure, is used to drive the piston structure to vibrate; The drive module is fixedly connected to the variable cavity piston via the second annular plate; the piston structure includes a pressure diaphragm flange and an elastic diaphragm. The pressure-film flange is fixedly connected to the first annular plate; The elastic membrane is disposed between the pressure flange and the first annular sheet; The pressure-film flange is provided with multiple fastening screws; The central axis of the pressure-film flange coincides with the central axis of the body; Each of the fastening pins is perpendicular to the central axis of the pressure-film flange; The piston structure also includes a first piston and a second piston; The vibration table includes a connecting shaft; The first piston is fitted onto the second piston; The pressure-film flange is fitted onto the first piston; A membrane pressure ring plate is provided at one end of the first piston near the first annular plate; The second piston is threadedly connected to the connecting shaft via an adjusting nut; The outer cylindrical surface of the first piston near the connecting shaft is provided with external threads; The piston structure also includes a limiting ring, a guide ring, and a locking ring; The limiting ring is disposed on the first piston and close to the connecting shaft; The guide ring is sleeved on the first piston; The inner diameter of the guide ring near the pressure diaphragm flange is equal to the outer diameter of the first piston; The inner diameter of the guide ring in the middle is smaller than the outer diameter of the first piston; The guide ring is provided with internal threads; The outer circumferential surface of the connecting shaft is provided with an external thread; The outer circumferential surface of the pressure-film flange is provided with external threads; The locking ring is provided with an internal thread. When the first piston is in a fixed state and the second piston is in a movable state, the pressure diaphragm flange is threadedly connected to the locking ring. When the first piston and the second piston are both in a movable state, the connecting shaft is threadedly connected to the locking ring. The guide ring is threadedly connected to the first piston.

2. A variable parameter piston exciter according to claim 1 wherein, Multiple sets of the gas film generating structures are disposed on the outer circumferential surface of the piston body, and the multiple sets of the gas film generating structures are evenly arranged around the central axis of the piston body.

3. A variable parameter piston exciter according to claim 2, wherein Each set of the air film generating structures includes multiple interconnecting air holes, annular air grooves, sealing rings, and inflation connectors. Each of the aforementioned connecting air holes is in communication with the annular air groove; The plurality of the communicating air holes are evenly arranged circumferentially around the central axis of the annular air groove; The sealing ring is fixedly connected to the piston body; The inflation connector is connected to the annular air groove through the hole in the sealing ring plate; The inflation joint circumscribes the inflation device.

4. A variable parameter piston exciter according to claim 3 wherein, The piston body further comprises a first inner cavity and a second inner cavity; The first inner cavity is in communication with the second inner cavity; The inflation joints are arranged on the cavity wall of the second inner cavity.

5. A variable parameter piston exciter according to claim 4 wherein, The cavity-changing piston further comprises a connecting ring and a plurality of driving rods; The connecting ring is fixedly connected with the cavity-changing piston; Each of the driving rods is fixedly connected with the connecting ring; The plurality of driving rods are parallel to each other; Each of the driving rods is fixedly connected with the driving module.

6. A variable parameter piston exciter according to claim 5 wherein, The driving module comprises a support plate, a connecting plate, a connecting mechanism, a motor and a guide rail; Each of the driving rods is fixedly connected with the connecting plate; The support plate is arranged on the guide rail; The connecting plate and the support plate are connected through the connecting mechanism; The motor is connected with the guide rail, and the motor drives the support plate to move along the guide rail.

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