An air-tightness detection device and method for an accordion body

Abstract

The present application relates to the technical field of musical instrument detection equipment, in particular to a piano body air tightness detection device and method for an accordion, comprising a workbench, a rigid vacuum chamber, a vacuum pump, a pressure sensor, a flow sensor, a first valve and a control unit; the integrated design of the rigid vacuum chamber to establish an external negative pressure environment combined with a negative pressure driven clamping assembly avoids the problems of multiple links and slow response existing in the traditional indirect measurement method of air bags; the configured pressure sensor and flow sensor directly and real-timely monitor the pressure and air extraction flow in the chamber, replacing the liquid column or air bag deformation observation method which is easily affected by temperature and elastic deformation, and improving the detection sensitivity and anti-interference ability for small leaks; ensuring that the piano body air tightness detection device and method for an accordion have high precision, high sensitivity, high reliability and strong anti-interference performance during the detection process.

Description

Technical Field

[0001] This invention relates to the field of musical instrument testing equipment technology, specifically to a device and method for testing the airtightness of an accordion body. Background Technology

[0002] The accordion is a sophisticated reed instrument whose tone, volume, and playing smoothness depend heavily on the airtightness of the entire bellows system. Poor airtightness can lead to air leakage, causing difficulty in opening and closing the bellows, unstable pitch, reduced volume, a dry tone, and even unwanted noise, severely impacting performance and the instrument's lifespan. Rapid and accurate airtightness testing is a crucial and frequently performed task during instrument manufacturing, tuning, and routine maintenance. Currently, accordion airtightness testing largely relies on the personal experience of repair technicians or tuners; existing technology lacks a standardized, quantitative, non-destructive, and efficient airtightness testing tool and method specifically for accordions.

[0003] To address the aforementioned issues, existing technologies have proposed several solutions. For example, utility model patent application CN202121404614.8 discloses an accordion airtightness testing device. This device places the entire accordion in a large airbag, inflates it, and then uses a vacuum pump to transfer the gas from the airbag to a U-shaped tubular pressure gauge consisting of inner and outer transparent covers and a water body. The device determines whether there is a leak by observing changes in the liquid level. However, this solution still has some problems. The device does not detect changes in pressure inside the accordion, but rather changes in the liquid level caused by gas leaking into the external airbag. This indirect measurement method involves multiple steps, has a slow response, lacks sensitivity to minor leaks, and is easily affected by factors such as ambient temperature and the elastic deformation of the airbag itself, leading to misjudgments. Furthermore, most existing technologies rely on mechanical liquid level observation, lacking the participation of intelligent sensing systems, making it impossible to automate, digitize, and accurately detect the process, thus failing to meet the higher requirements for detection accuracy and efficiency in modern musical instrument manufacturing and maintenance. Summary of the Invention

[0004] The purpose of this invention is to provide a device and method for detecting the air tightness of an accordion body, in order to solve the problems of existing accordion body air tightness detection devices having multiple measurement steps, slow response, insufficient sensitivity to minor leaks, and being easily affected by factors such as ambient temperature and the elastic deformation of the air bladder itself, leading to misjudgments.

[0005] To achieve the above objectives, the present invention provides the following technical solution: An accordion body airtightness testing device and method are disclosed, comprising a workbench, a rigid vacuum chamber, a vacuum pump, a pressure sensor, a flow sensor, a first valve, and a control unit. The rigid vacuum chamber, vacuum pump, and control unit are all mounted on the workbench. The rigid vacuum chamber contains a vacuum cavity, within which is placed the accordion body to be tested. The accordion body includes a treble enclosure and a bass enclosure, with a mounting platform between the two enclosures. The pressure sensor is installed within the rigid vacuum chamber. An air outlet is provided on the rigid vacuum chamber and connected to the vacuum pump via an air pipe. The flow sensor is installed within the air outlet. The first valve is installed between the air outlet and the vacuum pump. The vacuum pump, pressure sensor, flow sensor, and first valve are all electrically connected to the control unit. Clamping assemblies are provided at both the front and rear ends of the rigid vacuum chamber. The device comprises multiple clamping assemblies, each equipped with a clamping plate. These clamping plates are slidably connected to the front and rear ends of a rigid vacuum chamber. The clamping assemblies are driven by the negative pressure within the vacuum chamber to move the clamping plates toward the high-pitched and low-pitched instrument housings, respectively. This solution, through the integrated design of establishing an external negative pressure environment using a rigid vacuum chamber and driving the clamping assemblies with negative pressure, avoids the problems of multiple steps and slow response associated with traditional indirect airbag measurement methods. The high-precision pressure and flow sensors configured in this solution directly and in real-time monitor the pressure and airflow within the chamber, replacing the liquid column or airbag deformation observation method which is susceptible to temperature and elastic deformation. This improves the detection sensitivity and anti-interference capability for minor leaks, ensuring that the airtightness testing device and method for accordions exhibit high precision, high sensitivity, high reliability, and strong anti-interference performance during the testing process.

[0006] Preferably, the clamping assembly includes a piston cylinder, a drive piston, and a piston rod. Multiple piston cylinders are disposed at the front and rear ends of the rigid vacuum chamber. One end of each piston cylinder near the rigid vacuum chamber is connected to the vacuum cavity, and the other end is connected to the external air. Multiple drive pistons are slidably connected within the multiple piston cylinders, and multiple piston rods are connected to the ends of the multiple drive pistons near the vacuum cavity. This solution utilizes a pressure difference drive design, where the piston cylinder is connected to the vacuum cavity and its other end is exposed to the atmosphere. It uses the pressure difference naturally formed between the vacuum cavity and the external environment during vacuuming as a power source to automatically drive the piston and piston rod to move the clamping plate to perform the sealing clamping action. This avoids the structural complexity, high cost, and control delay issues associated with traditional devices that require additional electric, pneumatic, or hydraulic drive systems. It ensures the accordion body airtightness testing device's rapid response, structural simplicity, operational economy, and synchronous action during the sealing execution phase.

[0007] Preferably, each of the multiple driving pistons has a clamping rod installed at the end furthest from the vacuum chamber, and each of the multiple clamping rods is fitted with a pre-compression spring. The two ends of the pre-compression spring are respectively connected to the driving piston and the inner wall of the piston cylinder. This solution, by setting a mechanical pre-tightening structure of clamping rods and pre-compression springs on the driving piston, applies a continuous initial pre-sealing force to the accordion case before vacuuming. This effectively avoids the detection failure problem caused by premature connection of internal and external air pressure due to assembly gaps before the establishment of the main sealing force in traditional testing. It ensures the airtightness foundation of the accordion case airtightness testing device at the beginning of the testing stage, improves the accuracy and reliability of the test data, and achieves safety redundancy through a purely mechanical structure.

[0008] Preferably, anti-slip pads are installed on the contact surfaces of the multiple clamping plates with the tweeter and woofer housings. The anti-slip pads are made of rubber or polyurethane elastic material. This solution, by setting rubber or polyurethane anti-slip pads on the contact surfaces of the clamping plates, utilizes the high coefficient of friction and elastic deformation characteristics of the material itself to avoid sealing failure and positioning deviation caused by relative sliding between the clamping plates and the housing surface during the testing process. At the same time, the adaptive deformation of the elastic material compensates for the micro-unevenness of the contact surface, ensuring the stability of the accordion body airtightness testing device when sealing pressure is applied, the uniformity of the contact seal, and the repeatability accuracy of the entire testing process.

[0009] Preferably, the outer wall of the rigid vacuum chamber is made of transparent material. The rigid vacuum chamber is composed of an upper cover and a lower base. The upper cover and the lower base are hinged on one side, and a sealing ring is provided between the upper cover and the lower base. This solution, by adopting a transparent outer wall and a split hinged upper cover, achieves visualization of the testing process and convenience of accordion assembly and disassembly while ensuring vacuum sealing. It avoids the problems of inconvenient operation, difficult status observation, and cumbersome troubleshooting that exist in traditional closed testing devices, and improves the operability, maintenance efficiency, and human-computer interaction experience of the accordion body airtightness testing device.

[0010] Preferably, the mounting platform has a detection channel inside, and a tracer gas cylinder is installed on the workbench. The detection channel is connected to the tracer gas cylinder, the treble accordion enclosure, and the bass accordion enclosure. A second valve is provided between the tracer gas cylinder and the detection channel, and the second valve is electrically connected to the control unit. This solution, by designing a detection channel inside the mounting platform and connecting it to the tracer gas cylinder, constructs an integrated tracer gas injection path. This allows the device to automatically inject tracer gas into the accordion body to establish positive pressure after detecting a leak. This avoids the inefficiency of traditional detection methods that cannot accurately locate the leak point and rely on manual experience to check point by point. It ensures the accuracy, speed, and automation of the leak location stage in the accordion body airtightness detection method.

[0011] Preferably, multiple acoustic sensors are arrayed on the side wall of the lower base, and all of the acoustic sensors are electrically connected to the control unit. This solution constructs a distributed acoustic signal acquisition network by arranging multiple acoustic sensors in an array on the side wall of the lower base and linking them with the control unit. It uses the acoustic wave characteristics generated when the tracer gas leaks to perform spatial positioning, avoiding the problems of large blind spots and inaccurate leak point identification in traditional single sensor detection. This ensures the detection coverage and positioning accuracy of the airtightness detection device for the accordion body for leak points in complex curved surfaces and hidden parts of the accordion body, and realizes a technological leap from qualitative judgment to precise positioning in leak detection.

[0012] The present invention also provides a method for testing the airtightness of an accordion body using the above-mentioned method, comprising the following steps: S1: Preparation and pre-sealing steps: Open the top cover, install the tweeter and woofer enclosures (with bellows removed) on the left and right ends of the mounting platform respectively, ensuring that the tweeter and woofer enclosures are aligned with the clamping plates at both ends, and then close and lock the top cover. S2: Main seal establishment and vacuuming steps: Start the vacuum pump, and the control unit controls the opening of valve number one to evacuate the vacuum chamber; The negative pressure formed in the vacuum chamber is transmitted to the piston cylinder, and drives the piston to work together with the preload spring to drive the piston rod and clamping plate to press the contact surface between the instrument body and the mounting platform with greater pressure; During this process, the flow sensor monitors the gas flow in real time. S3: Macroscopic Leakage Judgment Step: During the vacuuming process, if the reading of the flow sensor continues to be higher than the first preset threshold within a predetermined time, the control unit determines that there is a macroscopic leak in the instrument body, and the control unit controls the vacuum pump to stop and issues an alarm signal. S4: Microscopic Leakage Judgment Step: If the reading of the flow sensor decreases and stabilizes below the second preset threshold, the control unit controls the first valve to close and enters the pressure holding stage; the pressure sensor monitors the pressure change rate in the vacuum chamber, and if the change rate exceeds the third preset threshold, it is determined that there is a microscopic leak in the instrument body; S5: Leakage point location steps: After determining that there is a macroscopic or microscopic leak, the control unit opens valve No. 2, allowing the tracer gas in the tracer gas cylinder to enter the interior of the high-pitched and low-pitched piano boxes simultaneously through the detection channel and form a positive pressure; the leakage sound wave signal is collected by multiple acoustic sensors arrayed on the side wall of the lower base, and the control unit processes it to generate an acoustic imaging map to accurately locate the leak point.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention, through the integrated design of establishing an external negative pressure environment using a rigid vacuum chamber and a negative pressure-driven clamping assembly, avoids the problems of multiple steps and slow response inherent in traditional indirect airbag measurement methods. The high-precision pressure and flow sensors configured in this solution directly and in real-time monitor the pressure inside the chamber and the airflow rate, replacing the liquid column or airbag deformation observation method which is easily affected by temperature and elastic deformation, thus improving the detection sensitivity and anti-interference capability for minute leaks. This ensures that the airtightness detection device and method for accordions have high precision, high sensitivity, high reliability, and strong anti-interference performance during the detection process.

[0014] 2. This invention utilizes a pressure difference drive design that connects the piston cylinder to the vacuum chamber and exposes the other end to the atmosphere. It uses the pressure difference naturally formed between the vacuum chamber and the external environment during vacuuming as a power source to automatically drive the piston and piston rod to drive the clamping plate to perform the sealing and clamping action. This avoids the structural complexity, high cost, and control delay problems caused by the need for additional electric, pneumatic, or hydraulic drive systems in traditional devices. It ensures the accordion body airtightness detection device has a fast response, simple structure, economical operation, and synchronous action in the sealing execution stage.

[0015] 3. This invention constructs an integrated tracer gas injection path by opening a detection channel inside the mounting platform and connecting it to a tracer gas cylinder. This allows the device to automatically inject tracer gas into the accordion body to establish positive pressure after a leak is detected. This avoids the inefficiency of traditional detection methods that cannot accurately locate the leak point and rely on manual experience to check point by point. It ensures the accuracy, speed and automation of the leak location stage in the accordion body airtightness detection method. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the airtightness testing device for an accordion body according to the present invention. Figure 2 This is a diagram showing the state of multiple clamping plates being pre-clamped in the accordion airtightness testing device of the present invention. Figure 3 This is a front view of the accordion body airtightness testing device of the present invention; Figure 4 For the present invention Figure 3 Sectional view at point AA; Figure 5 For the present invention Figure 4 Sectional view at point BB; Figure 6 This is a flowchart of the method for testing the airtightness of an accordion body according to the present invention.

[0017] In the diagram: 1. Workbench; 101. Mounting platform; 2. Rigid vacuum chamber; 201. Vacuum cavity; 202. Gas outlet; 203. Top cover plate; 204. Lower base; 205. Sealing ring; 3. Vacuum pump; 401. Pressure sensor; 402. Flow sensor; 403. Acoustic sensor; 501. Valve No. 1; 502. Valve No. 2; 6. Control unit; 701. Tweeter enclosure; 702. Bass enclosure; 801. Piston cylinder; 802. Drive piston; 803. Piston rod; 804. Clamping plate; 805. Clamping rod; 806. Preload spring; 807. Anti-slip pad; 901. Detection channel; 902. Tracer gas cylinder. Detailed Implementation

[0018] Please see Figures 1 to 6 This invention provides a device and method for detecting the airtightness of an accordion body, the technical solution of which is as follows: Please refer to the following: A device and method for testing the airtightness of an accordion body. Figures 1 to 6The system includes a workbench 1, a rigid vacuum chamber 2, a vacuum pump 3, a pressure sensor 401, a flow sensor 402, a first valve 501, and a control unit 6. The workbench 1 provides a stable support foundation for the entire device. The rigid vacuum chamber 2, vacuum pump 3, and control unit 6 are all mounted on the workbench 1. To ensure that the operator can directly observe the situation inside the chamber, the outer wall of the rigid vacuum chamber 2 is made of transparent acrylic material. The rigid vacuum chamber 2 consists of an upper cover plate 203 and a lower base 204. One side of the upper cover plate 203 and the lower base 204 are hinged together, and the other side can be locked by a buckle or lock. A sealing ring 205 is embedded at the joint surface of the upper cover plate 203 and the lower base 204 to ensure the airtightness of the vacuum chamber 201. The rigid vacuum chamber 2 contains a vacuum cavity 201, within which is placed the accordion body to be tested. The body includes a tweeter housing 701 and a woofer housing 702. A mounting platform 101 is positioned between the tweeter housing 701 and the woofer housing 702. A detection channel 901 is opened inside the mounting platform 101. A tracer gas cylinder 902 is mounted on the workbench 1. The detection channel 901 communicates with the tracer gas cylinder 902, the tweeter housing 701, and the woofer housing 702. A second valve 502 is located between the tracer gas cylinder 902 and the detection channel 901, and is electrically connected to the control unit 6. Multiple acoustic sensors 403 are arrayed on the side wall of the lower base 204, and all acoustic sensors 403 are electrically connected to the control unit 6. Force sensor 401 is installed inside rigid vacuum chamber 2. A gas outlet 202 is provided on rigid vacuum chamber 2, and the gas outlet 202 is connected to vacuum pump 3 via a gas pipe. Flow sensor 402 is installed inside gas outlet 202. Valve 501 is installed between gas outlet 202 and vacuum pump 3. Vacuum pump 3, pressure sensor 401, flow sensor 402, and valve 501 are all electrically connected to control unit 6. Both valve 501 and valve 502 are high-sealing electromagnetic vacuum valves. Clamping assemblies are provided at both the front and rear ends of rigid vacuum chamber 2. Multiple clamping assemblies are equipped with clamping plates 804, which are slidably connected to the front and rear ends of rigid vacuum chamber 2. The clamping assemblies pass through the vacuum chamber 201. The negative pressure drives multiple clamping plates 804 to move towards the tweeter housing 701 and the woofer housing 702, respectively. The clamping assembly includes piston cylinders 801, drive pistons 802, and piston rods 803. The piston cylinders 801 are located at the front and rear ends of the rigid vacuum chamber 2. One end of the piston cylinders 801 near the rigid vacuum chamber 2 is connected to the vacuum chamber 201, and the other end is connected to the outside air. The drive pistons 802 are slidably connected to the piston cylinders 801, and the piston rods 803 are connected to the ends of the drive pistons 802 near the vacuum chamber 201. Clamping rods 805 are installed on the ends of the drive pistons 802 away from the vacuum chamber 201, and preload springs 806 are sleeved on the clamping rods 805.The two ends of the preload spring 806 are connected to the inner walls of the drive piston 802 and the piston cylinder 801, respectively. Anti-slip pads 807, made of rubber or polyurethane elastic material, are installed on the contact surfaces of the multiple clamping plates 804 with the tweeter housing 701 and the woofer housing 702.

[0019] When working, please refer to Figures 1 to 6 Open the top cover 203 and place the accordion's high-pitched body 701 and low-pitched body 702 (with bellows removed) on the mounting platform 101 of the lower base 204. Under the action of the pre-compression spring 806, the clamping plates 804 at both ends slightly press the body through the anti-slip pads 807 to form an initial seal. Then close and lock the top cover 203.

[0020] The vacuum pump 3 is started by the control unit 6, and the valve 501 is opened to evacuate the vacuum chamber 201. As the pressure inside the vacuum chamber 201 decreases, the pressure difference between atmospheric pressure and the vacuum chamber 201 causes the drive piston 802 to work in conjunction with the preload of the preload spring 806 to drive the piston rod 803 and the clamping plate 804 to press the bellows interfaces of the tweeter enclosure 701 and the woofer enclosure 702 with greater pressure. During this process, the flow sensor 402 monitors the flow rate in real time. At the same time, during the evacuation process, the control unit 6 continuously reads the data from the flow sensor 402. If the flow rate remains above the first preset threshold for a predetermined time, it indicates that a large amount of gas is continuously flowing into the vacuum chamber 201. The control unit 6 will determine this as a macroscopic leak, immediately stop vacuuming, and sound an alarm. If the flow rate decreases and stabilizes below the second preset threshold, it indicates that the gas leakage rate is very slow. When the negative pressure value in the vacuum chamber 201 reaches the set value, the control unit 6 controls the first valve 501 to close, entering the pressure holding stage. At this time, the control unit 6 monitors the pressure change rate in the vacuum chamber 201 through the pressure sensor 401. If it exceeds the third preset threshold, it is determined that there is a microscopic leak.

[0021] After a leak is detected, the control unit 6 controls the second valve 502 to open, allowing the tracer gas to enter the instrument body and create positive pressure. When the gas escapes from the leak point, it will generate specific sound waves. At this time, the arrayed acoustic sensors 403 will capture these signals and process them by the software algorithm of the control unit 6. Finally, an acoustic image will be generated on the screen, which will intuitively show the precise location of the leak point.

[0022] The specific embodiment of the present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the embodiments described above. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and ideas of the present invention should still fall within the protection scope of the present invention.

Claims

1. A device for detecting the airtightness of an accordion body, characterized in that, The device includes a workbench, a rigid vacuum chamber, a vacuum pump, a pressure sensor, a flow sensor, a first valve, and a control unit. The rigid vacuum chamber, vacuum pump, and control unit are all mounted on the workbench. The rigid vacuum chamber has a vacuum cavity, and the accordion body to be tested is placed inside the vacuum cavity. The accordion body includes a tweeter box and a woofer box. A mounting platform is provided between the tweeter box and the woofer box. The pressure sensor is installed inside the rigid vacuum chamber. The rigid vacuum chamber has an air outlet, which is connected to the vacuum pump via an air pipe. The flow sensor is installed inside the air outlet. The first valve is installed between the air outlet and the vacuum pump. The vacuum pump, pressure sensor, flow sensor, and first valve are all electrically connected to the control unit. Clamping assemblies are provided at both the front and rear ends of the rigid vacuum chamber. Multiple clamping assemblies are equipped with clamping plates, which are slidably connected to the front and rear ends of the rigid vacuum chamber. The clamping assemblies are driven by the negative pressure inside the vacuum cavity to move the clamping plates toward the tweeter box and the woofer box, respectively. The clamping assembly includes a piston cylinder, a drive piston, and a piston rod. The piston cylinders are disposed at the front and rear ends of the rigid vacuum chamber. One end of the piston cylinders near the rigid vacuum chamber is connected to the vacuum chamber, and the other end is connected to the outside air. The drive pistons are slidably connected in the piston cylinders, and the piston rods are connected to the ends of the drive pistons near the vacuum chamber. Each of the multiple drive pistons is equipped with a clamping rod at the end away from the vacuum chamber, and a preload spring is sleeved on each of the multiple clamping rods. The two ends of the preload spring are respectively connected to the drive piston and the inner wall of the piston cylinder. The installation platform has a detection channel inside, and a tracer gas cylinder is installed on the workbench. The detection channel is connected to the tracer gas cylinder, the high-pitched piano box, and the low-pitched piano box. A second valve is provided between the tracer gas cylinder and the detection channel, and the second valve is electrically connected to the control unit. The rigid vacuum chamber is composed of an upper cover and a lower base. Multiple acoustic sensors are arrayed on the side wall of the lower base, and all of the acoustic sensors are electrically connected to the control unit.

2. The accordion body airtightness testing device according to claim 1, characterized in that: Anti-slip pads, made of rubber or polyurethane elastic material, are installed on the contact surfaces of the multiple clamping plates with the tweeter and woofer enclosures.

3. The accordion body airtightness testing device according to claim 1, characterized in that: The outer wall of the rigid vacuum chamber is made of transparent material. The upper cover and the lower base are hinged on one side, and a sealing ring is provided between the upper cover and the lower base.

4. A method for testing the airtightness of an accordion body, characterized in that: This method is applied at least to the accordion airtightness testing device according to any one of claims 1 to 3, and the specific method includes: S1: Preparation and pre-sealing steps: Open the top cover, install the tweeter and woofer enclosures (with bellows removed) on the left and right ends of the mounting platform respectively, ensuring that the tweeter and woofer enclosures are aligned with the clamping plates at both ends, and then close and lock the top cover. S2: Main seal establishment and vacuuming steps: Start the vacuum pump, and the control unit controls the opening of valve number one to evacuate the vacuum chamber; The negative pressure formed in the vacuum chamber is transmitted to the piston cylinder, and drives the piston to work together with the preload spring to drive the piston rod and clamping plate to press the contact surface between the instrument body and the mounting platform with greater pressure; During this process, the flow sensor monitors the gas flow in real time. S3: Macroscopic Leakage Judgment Step: During the vacuuming process, if the reading of the flow sensor continues to be higher than the first preset threshold within a predetermined time, the control unit determines that there is a macroscopic leak in the instrument body, and the control unit controls the vacuum pump to stop and issues an alarm signal. S4: Microscopic Leakage Judgment Step: If the reading of the flow sensor decreases and stabilizes below the second preset threshold, the control unit controls the first valve to close and enters the pressure holding stage; the pressure sensor monitors the pressure change rate in the vacuum chamber, and if the change rate exceeds the third preset threshold, it is determined that there is a microscopic leak in the instrument body; S5: Leakage point location steps: After determining that there is a macroscopic or microscopic leak, the control unit opens valve No. 2, allowing the tracer gas in the tracer gas cylinder to enter the interior of the high-pitched and low-pitched piano boxes simultaneously through the detection channel and form a positive pressure; the leakage sound wave signal is collected by multiple acoustic sensors arrayed on the side wall of the lower base, and the control unit processes it to generate an acoustic imaging map to accurately locate the leak point.

Images