Method for testing gas production and gas production rate of automobile airbag inflator based on high-speed camera

Abstract

The application discloses a kind of based on high-speed camera's automobile safety air bag gas generator gas production and gas production rate test method, set up a vertical hollow transparent cylindrical rigid container in normal pressure environment, a light piston is arranged in rigid container and contacted with air bag gas generator;The vertical movement track of piston in rigid container is recorded by high-speed camera during the ignition intense combustion process of air bag gas generator, is simplified into physical model, is converted into the linear motion process of piston and the volume change formed by rigid container, i.e.gas production of gas generator;Solving the volume change rate is gas production rate.The present application has reliable theoretical basis, convenient operation, and accurate measurement result provides certain technical support for actual research and production.

Description

A Test Method for Gas Generation Volume and Rate of Automotive Airbag Gas Generators Based on High-Speed ​​Cameras Technical Field

[0001] This invention relates to airbag gas generator testing technology, specifically to a method for testing the gas production volume and gas production rate of an automotive airbag gas generator based on a high-speed camera. Background Technology

[0002] With the rapid development of China's automotive industry, the number of car models and vehicles on the market is increasing. Based on road safety and consumers' growing emphasis on safety, higher and higher requirements are being placed on the area and performance of car airbag protection.

[0003] Current automotive airbags mainly consist of a gas generator and an airbag. The gas generator, a core component of the airbag, primarily comprises an ignition agent, a gas-generating agent, and a metal filter. The igniter ignites the ignition agent, which releases heat, causing a violent chemical reaction in the gas-generating agent, producing gases such as nitrogen. The metal filter filters out any remaining agent residue, and the gas enters the airbag through the inflation port. The gas generator's gas output and gas production rate are critical performance parameters, largely determining whether the airbag performance meets the requirements for protecting occupants from hard contact with the vehicle structure after a collision. The gas output determines the airbag volume, directly affecting the size of the airbag's protected area; the gas production rate determines the time it takes for the airbag to fill, ensuring that the airbag is fully inflated and reaches the designed position to support the occupant when they are thrown forward after a collision. Therefore, testing the gas output and gas production rate of the airbag gas generator is crucial during the component development stage.

[0004] Current gas generator technologies primarily determine gas production volume and rate through testing the gas-generating agent, estimating dosage differences across product series, and conducting closed combustion chamber tests (Tank tests) on the gas generator. These tests involve detonating the airbag gas generator within a sealed, rigid container and obtaining a pressure-time (pt) curve using a pressure sensor. Gas production volume is estimated from the pressure value, and the gas production rate is estimated from the slope of the pt curve. However, these methods do not provide accurate and intuitive data on gas generator production volume and rate, and thus have limitations in meeting increasingly stringent automotive collision safety standards.

[0005] Patent application number 200520104200.8 provides a performance testing device for an airbag gas generator, which can test the pressure-time curve, temperature, composition and concentration of the gas produced after the gas generator is ignited, as well as the composition and content of solid residue after combustion. However, this technical solution cannot measure the gas production volume and gas production rate.

[0006] The patent application number 201610586401.9 provides a performance testing device for airbag gas generators, which can realize the rapid opening and closing of the canister lid of the testing device, improving the convenience of existing testing devices. However, it is still based on existing testing and evaluation methods and devices, and cannot measure the gas production volume and gas production rate.

[0007] The patent application number 202021296314.8 provides a test pressure device for airbag gas generators, which solves the problems of existing airbag gas generator test devices being unable to effectively fix the tested product and the inconvenience of moving the airbag gas generator test device; however, it only improves the ease of operation of the existing test device and cannot measure the gas production volume and gas production rate. Summary of the Invention

[0008] Purpose of the invention: The purpose of this invention is to address the shortcomings of existing technologies and provide a method for testing the gas production volume and gas production rate of automotive airbag gas generators based on high-speed cameras. This method can measure the gas production volume, gas production rate, and dynamic changes of the airbag gas generator after ignition, providing an evaluation method for the research and development and production of actual airbag gas generators.

[0009] Technical solution: The present invention provides a method for testing the gas production volume and gas production rate of an automotive airbag gas generator based on a high-speed camera, comprising the following steps:

[0010] Step S1: Set up the test device; the test device includes a rigid container, a piston, and a high-speed camera; the rigid container is a transparent hollow cylinder, and an airbag gas generator is fixed at the bottom of the rigid container. The piston is located inside the rigid container, and the piston as a whole is a hemispherical shell with the opening facing downwards. The high-speed camera is placed perpendicular to the central axis of the rigid container; a positioning cantilever is fixed above the rigid container, and a square positioning hole is provided on the positioning cantilever at the position corresponding to the central axis of the rigid container. A positioning post is installed on the top of the piston, and the positioning post is adapted to the positioning hole.

[0011] Step S2: Activate the ignition device inside the rigid container and simultaneously start the high-speed camera and data recording device; after ignition, the piston moves vertically linearly inside the rigid container; the high-speed camera captures the vertical movement trajectory of the piston in the rigid container.

[0012] Based on the motion trajectory data collected in real time by the high-speed camera, the data is converted into the linear motion process of the piston and the volume change of the space enclosed by the piston and the rigid container, thereby obtaining the gas production rate of the gas generator; then the volume change rate of the space enclosed by the piston and the rigid container is calculated, which is the gas production rate of the gas generator.

[0013] In this process, a high-speed camera captures the linear motion trajectory of a piston within a rigid container, collecting the piston's linear displacement and the corresponding time intervals. A mathematical method is then used to fit its polynomial equation.

[0014] (1)

[0015] In equation (1), , For the linear motion displacement of the piston, in units ; These are undetermined constants; For time variables, units ; This is for intermediate calculations;

[0016] The volume of the airbag gas generator was measured before the test. ,unit Then, the initial gas volume within the space formed by the piston and the rigid container before the test... for:

[0017] (2)

[0018] In equation (2), The initial gas volume of the system, in liters ( ), The inner radius of the piston bottom, in units ;

[0019] Gas volume within the airbag gas generator ignition and combustion system The sum of the volumes of the closed space formed by the piston hemispherical shell and the rigid container, combined with equation (1), represents the linear displacement of the piston. The gas volume within the airbag gas generator ignition and combustion system for:

[0020] (3)

[0021] In equation (3), , The inner radius of the rigid container, in units The remaining parameters are the same as in equations (1) and (2);

[0022] The gas production of the airbag gas generator can be obtained from equations (2) and (3). For, unit :

[0023] (4)

[0024] Equation (4) for time variables Differential calculation to determine the gas generation rate of the airbag gas generator:

[0025] (5)

[0026] In equation (5), The gas generation rate of the airbag gas generator, in units of: The remaining parameters are the same as in equation (4);

[0027] The gas production of the airbag gas generator and its dynamic change over time can be calculated according to equation (4).

[0028] The gas generation rate of the airbag gas generator and its dynamic change over time can be solved according to equation (5).

[0029] Furthermore, the rigid container has equally spaced graduations on its outer wall, and the inner diameter of the rigid container is 2R; the inner diameter of the lightweight piston is 2r; both the rigid container and the piston are made of a smooth, rigid material; the diameter of the piston's semi-outer surface matches the inner diameter of the rigid container; the contact area between the rigid container and the piston is coated with a lubricating coating, and the effects of friction and piston mass are ignored; the above dimensions are in units of... .

[0030] Furthermore, the rigid container has a base at its bottom, which is detachably and sealed to the rigid container column. The central area of ​​the base has bolts and wiring harness holes that can be connected to the gas generator. The detonation wiring harness of the gas generator passes through the wiring harness holes on the base and is connected to the ignition device. The outer ring of the base has fixing bolt holes.

[0031] Furthermore, the positioning cantilever is rigidly connected to the rigid container, and during testing, the positioning post passes through the positioning hole and can slide freely within the positioning hole.

[0032] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0033] (1) The rigid container of the present invention is designed as a transparent hollow cylinder, which facilitates the recording of the piston's movement trajectory by a high-speed camera throughout the test process; the cross-section of the positioning column matches the shape and size of the positioning hole, effectively limiting the rotation of the piston; the part of the piston that contacts the expanding gas is a hemispherical shell structure, which makes the contact position with the hollow cylindrical rigid container column smooth, preventing stress concentration, making the piston uniformly stressed, and making the linear motion process more stable.

[0034] (2) The present invention can measure the vertical motion trajectory of the piston in the rigid container by using a high-speed camera, and convert it into the linear motion process of the piston and the volume change enclosed by the rigid container, which is the gas production of the gas generator; the volume change rate is the gas production rate.

[0035] (3) This invention has a reliable theoretical basis, is easy to operate, and provides accurate measurement results, thus providing certain technical support for actual research and development and production. Attached Figure Description

[0036] Figure 1 is a schematic diagram of the rigid container structure of the present invention;

[0037] Figure 2 is a schematic diagram of the piston structure of the present invention;

[0038] Figure 3 is a schematic diagram of the rigid container and piston assembly of the present invention;

[0039] Figure 4 is a partial structural schematic diagram of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be described in detail below, but the scope of protection of the present invention is not limited to the embodiments described.

[0041] A vertically placed, hollow, transparent, cylindrical rigid container 1 is set up under normal pressure. A lightweight piston 4 is placed inside the rigid container 1 and is in contact with an airbag gas generator 8. The vertical movement trajectory of the piston 4 within the rigid container 1 during the intense combustion process of the airbag gas generator 8 is recorded by a high-speed camera 9. This is simplified into a physical model, which is transformed into the linear movement process of the piston 4 and the volume change enclosed by the rigid container 1, which is the gas production rate of the gas generator 8. Solving for the volume change rate gives the gas production rate.

[0042] The theoretical derivation is as follows: the rigid container 1 is made of transparent material, with equally spaced graduations on its outer wall, and an inner diameter of 2R; the lightweight piston 4 is hemispherical in shape, with an inner diameter of 2r; both the rigid container 1 and the piston 4 are made of smooth, rigid material, with a lubricating coating on the contact parts, and the effects of friction and the mass of the piston 4 are ignored; the above dimensions are in millimeters. .

[0043] Example 1

[0044] As shown in Figures 1 to 4, in the testing apparatus of this embodiment, the outer wall of the rigid container 1 is provided with equally spaced graduations, and the inner diameter of the rigid container 1 is 2R; the inner diameter of the lightweight piston 4 is 2r; both the rigid container 1 and the piston 4 are made of smooth, rigid material; the semi-outer surface diameter of the piston 4 matches the inner diameter of the rigid container 1, and the contact portion between the rigid container 1 and the piston 4 is coated with a lubricating coating. The effects of friction and the mass of the piston 4 are ignored; the above dimensions are in units of _____. The rigid container 1 has a base 2 at its bottom, which is detachably and sealed to the column of the rigid container 1. The central area of ​​the base 2 has bolts and wiring harness holes for connection to the gas generator 8. The detonation wiring harness of the gas generator 8 passes through the wiring harness holes on the base 2 and is connected to the ignition device. The outer ring of the base has fixing bolt holes. The positioning cantilever is rigidly connected to the rigid container 1. A square positioning hole 3 is provided on the positioning cantilever at a position corresponding to the central axis of the rigid container 1. The positioning hole 3 is adapted to the shape and size of the positioning column 5.

[0045] The aforementioned testing device, its connections, and sealing points can withstand 500... The above design pressure, in this embodiment, the high-speed camera sampling frequency is 1000. .

[0046] During testing, the detonation harness of the airbag gas generator 8 is first passed through the base harness hole of the rigid container 1, and the harness hole of the base 2 is sealed. The airbag gas generator 8 is then fixed to the base 2 with bolts. The piston 4 is placed inside the rigid container 1, the positioning pin 5 passes through the positioning hole 3, and a lubricating coating is applied to the contact part. The piston 4 is positioned at the starting position of the scale line on the outside of the rigid container 1, and the base 2 is sealed to the rigid container 1. The base 2 is then connected to the fixed base through the fixing bolt holes on the outer ring of the base to fix the entire test system. The high-speed camera 9 is placed perpendicular to the central axis of the rigid container 1. The detonation harness of the airbag gas generator 8 is connected to the ignition device, the high-speed camera 9 is connected to the data recording device, and the ignition device is connected to the data recording device (e.g., a USB storage device).

[0047] The ignition device is activated, and the high-speed camera 9 and data recording device are simultaneously started. The igniter detonates the ignition agent, which ignites the gas-producing agent, rapidly releasing a large amount of gas. The gas pushes the piston 4 to move linearly inside the rigid container 1, and the high-speed camera 9 collects the trajectory information of the piston 4. After the piston 4 stops, all equipment is shut down, and all data and image information is recorded by the data recording device.

[0048] Based on the above theoretical derivation, the vertical motion trajectory of piston 4 in the transparent hollow cylindrical rigid container 1, measured by high-speed camera 9, is transformed into the linear motion process of piston 4 and the volume change enclosed by rigid container 1, which is the gas production of gas generator 8; solving for the volume change rate is the gas production rate.

[0049] Example 2

[0050] The test device structure in this embodiment is the same as that in the above embodiment, as detailed below:

[0051] Referring to Figure 1, the rigid container 1, its base 2, and the positioning cantilever are all made of transparent tempered glass with a tempering degree of 2-4. It can withstand a stress of 95%. Furthermore, it has a smooth surface and a low coefficient of friction. Rigid container 1 is 450 mm long. , inner diameter 26 Wall thickness 3 It is designed to measure a gas capacity of approximately 200 liters; it is equipped with a measuring range of 400... The scale lines have adjacent scale values ​​of 1. The base and the rigid container are detachably and sealed together. The cantilever is positioned with a side length of 1 corresponding to the central axis of the rigid container. Square positioning hole 3.

[0052] Referring to Figure 2, the piston 4 has a hemispherical shell with an outer surface diameter of 26 mm. Wall thickness 2 Piston 4 has a positioning post 5 on its top outer side, which is 460 mm long. The cross-section has a side length of 1. The piston is square; the entire piston 4 is made of dark tempered glass with a tempering degree of 2~4. It can withstand a stress of 95%. It also has a smooth surface and a low coefficient of friction.

[0053] Referring to Figures 3 and 4, during testing, first pass the detonation harness of the airbag gas generator through the base harness hole of the rigid container, and seal the base harness hole; the airbag gas generator 8 is fixed to the base 2 by base bolts. Place the piston 4 inside the rigid container 1, with the positioning pin 5 passing through the positioning hole 3. Apply a lubricating coating to the contact portion, and position the piston 4 at the starting position of the scale line on the outside of the rigid container. Seal the base 2 to the rigid container 1; connect the base to the fixed base through the fixing bolt holes on the outer ring of the base to secure the entire test system. The high-speed camera 9 is placed perpendicular to the central axis of the rigid container 1. The detonation harness of the airbag gas generator is connected to the ignition device, the high-speed camera 9 is connected to the data recording device, and the ignition device is connected to the data recording device.

[0054] Example 3

[0055] The test device structure and connection method in this embodiment are the same as in Embodiments 1 and 2. The specific method for testing gas production volume and gas production rate includes the following steps:

[0056] Step S1: Set up the test device; the test device includes a rigid container 1, a piston 4 and a high-speed camera 9; the rigid container 1 is a transparent hollow cylinder, and an airbag gas generator 8 is fixed at the bottom of the rigid container 1. The piston 4 is located inside the rigid container 1, and the piston 4 is a hemispherical shell with the opening facing downward. The high-speed camera 9 is placed perpendicular to the central axis of the rigid container 1; a positioning cantilever is fixed above the rigid container 1, and a positioning post is installed at the top of the piston 4.

[0057] Step S2: Activate the ignition device inside the rigid container 1 and simultaneously start the high-speed camera 9 and the data recording device; after ignition, the piston 4 moves vertically linearly inside the rigid container 1; the high-speed camera 9 collects the vertical movement trajectory of the piston 4 in the rigid container 1; based on the motion trajectory data collected in real time by the high-speed camera 9, convert it into the linear movement process of the piston 4 and the volume change of the space enclosed by the piston 4 and the rigid container 1, and then obtain the gas production rate of the gas generator 8; then solve for the volume change rate of the space enclosed by the piston 4 and the rigid container 1, which is the gas production rate of the gas generator 8;

[0058] Among them, the high-speed camera 9 captures the linear motion trajectory of the piston 4 in the rigid container 1, collects the linear motion displacement of the piston 4 and the corresponding time, and uses mathematical methods to fit its polynomial equation:

[0059] (1)

[0060] In equation (1), , For the linear motion displacement of piston 4, in units ; These are undetermined constants; For time variables, units ;

[0061] Before testing, the volume of the airbag gas generator 8 was measured. ,unit Therefore, the initial gas volume in the space formed by piston 4 and rigid container 1 before the test is:

[0062] (2)

[0063] In equation (2), The initial gas volume of the system, in liters ( ), The inner radius of the piston's four-hemispherical shell, in units. ;

[0064] Gas volume within the airbag gas generator 8 ignition combustion system The sum of the volumes of the closed space formed by the hemispherical shell of piston 4 and the rigid container 1, combined with equation (1), represents the linear displacement of piston 4. The gas volume inside the airbag gas generator 8-ignition combustion system for:

[0065] (3)

[0066] In equation (3), , The inner radius of rigid container 1, in units The remaining parameters are the same as in equations (1) and (2);

[0067] The gas production of the airbag gas generator 8 can be obtained from equations (2) and (3). For, unit :

[0068] (4)

[0069] Equation (4) for time variables Differential calculation to determine the gas generation rate of the gas generator 8 in the airbag:

[0070] (5)

[0071] In equation (5), The gas production rate of the airbag gas generator 8, in units of: The remaining parameters are the same as in equation (4);

[0072] The gas production of the airbag gas generator 8 and its dynamic change over time can be solved according to equation (4);

[0073] The gas generation rate of the airbag gas generator 8 and its dynamic change over time can be solved according to equation (5).

Claims

1. A method for testing the gas production volume and gas production rate of an automotive airbag gas generator based on a high-speed camera, characterized in that, Includes the following steps: Step S1: Set up the test device; the test device includes a rigid container, a piston, and a high-speed camera; the rigid container is a transparent hollow cylinder, and a gas generator is fixed at the bottom of the rigid container. The piston is located inside the rigid container, and the piston as a whole is a hemispherical shell with its opening facing downwards. The high-speed camera is placed perpendicular to the central axis of the rigid container; a positioning cantilever is fixed above the rigid container, and a square positioning hole is provided on the positioning cantilever at a position corresponding to the central axis of the rigid container. A positioning post is installed on the top of the piston, and the positioning post is adapted to the positioning hole; Step S2: Activate the ignition device inside the rigid container, and simultaneously start the high-speed camera and data recording device. After ignition, the piston moves vertically linearly inside the rigid container. A high-speed camera captures the vertical trajectory of the piston within the rigid container. Based on the real-time motion trajectory data captured by the high-speed camera, the data is converted into the linear motion process of the piston and the volume change of the space enclosed by the piston and the rigid container, thus obtaining the gas production rate of the gas generator. Next, the volume change rate of the space enclosed by the piston and the rigid container is calculated; this volume change rate is the gas production rate of the gas generator. Specifically, the high-speed camera captures the linear motion trajectory of the piston within the rigid container, collecting the piston's linear displacement and the corresponding time, and uses mathematical methods to fit its polynomial equation. In equation (1), ， The displacement is the linear motion displacement of the piston; These are undetermined constants; For time variables, This is an intermediate calculation; the volume of the airbag gas generator was measured before the test. Then, the initial gas volume within the space formed by the piston and the rigid container before the test... for: In equation (2), The inner radius of the piston bottom; the gas volume within the gas generator ignition and combustion system. The sum of the volumes of the closed space formed by the piston hemispherical shell and the rigid container, combined with equation (1), represents the linear displacement of the piston. The gas volume within the airbag gas generator ignition and combustion system for: In equation (3), The inner radius of the rigid container is given by equations (2) and (3); the gas production of the airbag gas generator can be obtained from these equations. as follows: (4) Equation (4) for time variable Differential calculation to determine the gas generation rate of the airbag gas generator: In equation (5), Let be the gas generation rate of the airbag gas generator; calculate the gas generation of the airbag gas generator and its dynamic change over time according to equation (4); calculate the gas generation rate of the airbag gas generator and its dynamic change over time according to equation (5).

2. The method for testing the gas production volume and gas production rate of an automotive airbag gas generator based on a high-speed camera according to claim 1, characterized in that: The rigid container has equally spaced graduations on its outer wall, and its inner diameter is 2R. Both the rigid container and the piston are made of smooth, rigid material. The diameter of the piston's semi-outer surface matches the inner diameter of the rigid container. The contact area between the rigid container and the piston is coated with a lubricating layer. The effects of friction and piston mass are ignored. The unit of measurement is [missing information]. 。 3. The method for testing the gas production volume and gas production rate of an automotive airbag gas generator based on a high-speed camera according to claim 1, characterized in that: The rigid container has a base at its bottom, which is detachably and sealed to the rigid container column. The central area of ​​the base has bolts and wiring harness holes that can be connected to the gas generator of the airbag. The ignition wiring harness of the gas generator passes through the wiring harness hole on the base and is connected to the ignition device. The outer ring of the base has fixing bolt holes.

4. The method for testing the gas production volume and gas production rate of an automotive airbag gas generator based on a high-speed camera according to claim 1, characterized in that: The positioning cantilever is rigidly connected to the rigid container. During testing, the positioning post passes through the positioning hole and can slide freely within the positioning hole.

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