A micro-mechanical acceleration detection structure for an automobile airbag

Abstract

The application provides a kind of micro-mechanical acceleration detection structure for automobile safety air bag, belongs to acceleration detection technical field, including substrate, movable mass block frame and cover plate, movable mass block frame is horizontally arranged between substrate and cover plate;Movable mass block frame is provided with four quadrant frames, movable mass block anchor point is arranged in the length direction in the quadrant frame, movable mass block anchor point is provided with support part connected with the quadrant frame, the lower end of movable mass block anchor point is fixed on the substrate;The middle part of movable mass block frame inside is provided with a plurality of movable combs, fixed detection comb is arranged between adjacent movable combs, fixed detection comb is provided with fixed comb anchor point, the lower end of fixed comb anchor point is fixed on the substrate, and the differential capacitance detection gap is formed between fixed detection comb and movable comb.The micro-mechanical acceleration detection structure for automobile safety air bag provided by the application adopts a brand-new frame structure and layout form, which greatly improves the reliability of the accelerometer.

Description

Technical Field

[0001] This invention belongs to the field of acceleration detection technology, and more specifically, relates to a micromechanical acceleration detection structure for automotive airbags. Background Technology

[0002] Micro-mechanical systems (MEMS) accelerometers are devices that sense the inertial acceleration of objects. They are mainly used to detect and measure acceleration, tilt, impact, vibration, and multi-degree-of-freedom motion, and are crucial components for navigation, orientation, and motion vehicle control. Due to the use of silicon MEMS fabrication technology, MEMS accelerometers have advantages such as small size, light weight, low power consumption, low cost, and mass production capability, and are widely used in the automotive industry, consumer electronics, and aerospace. Airbags are an essential component for protecting drivers and passengers and are one of the core safety features of automobiles.

[0003] MEMS accelerometers meet the requirements of small size and low cost for automotive airbag accelerometers. These accelerometers detect the acceleration generated during a car collision, requiring a large range and high reliability, with high reliability being the most critical factor. Traditional MEMS accelerometers can be designed with arbitrary ranges according to application requirements, making it easy to design and manufacture large-range accelerometers. However, MEMS accelerometers are prone to collision damage when subjected to overloaded external signals. Therefore, researching highly reliable MEMS accelerometers for airbags is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a micromechanical acceleration detection structure for automotive airbags, which adopts a brand-new frame structure and layout, greatly improving the reliability of the accelerometer.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a micromechanical acceleration detection structure for automotive airbags is provided, comprising a substrate, a movable mass block frame, and a cover plate, wherein the cover plate is disposed above the substrate, and the movable mass block frame is horizontally disposed between the substrate and the cover plate;

[0006] The inner corner of the movable mass block frame is provided with four quadrant frames. Anchor points of the movable mass block are provided along the length direction in the quadrant frames. A support part connected to the quadrant frame is provided on one side of the anchor point of the movable mass block. The lower end of the anchor point of the movable mass block is fixed on the base plate.

[0007] The inner side of the movable mass block frame has multiple movable comb teeth in the middle, and a fixed detection comb tooth is provided between adjacent movable comb teeth. The fixed detection comb tooth is provided with a fixed comb tooth anchor point, and the lower end of the fixed comb tooth anchor point is fixed on the substrate. A differential capacitance detection gap is formed between the fixed detection comb tooth and the movable comb tooth.

[0008] In one possible implementation, the active mass block frame includes a rectangular frame with a central partition beam. Side partition beams perpendicular to the central partition beam are located on both sides of the rectangular frame. The outer regions of the two side partition beams are divided into upper and lower quadrants by the central partition beam. The inner regions of the two side partition beams are divided into left and right detection areas by the central partition beam. Multiple fixed detection comb teeth and multiple active comb teeth are arranged laterally and spaced longitudinally within the detection areas.

[0009] In one possible implementation, the detection area is divided into several detection frames by multiple movable comb teeth. Two fixed detection comb teeth are arranged horizontally within each detection frame. Two fixed comb tooth anchor points are provided on opposite sides of the two fixed detection comb teeth within the same detection frame. The four fixed comb tooth anchor points within the same detection frame are staggered.

[0010] In one possible implementation, the four side beams of the rectangular frame, the side partition beams, and the central partition beam each have multiple structural frames arranged sequentially along their respective length directions, and the structural frames have through release holes at the top and bottom.

[0011] In one possible implementation, the movable comb teeth and the intermediate partition are arranged opposite to the intermediate walls of two adjacent structural frames.

[0012] In one possible implementation, the corners of the quadrant frame, the detection frame, and the structure frame are all rounded.

[0013] In one possible implementation, the support includes two extension beams arranged parallel to each other along the length of the quadrant frame. The two ends of the extension beams are respectively connected to connecting beams. The two extension beams and the two connecting beams at both ends constitute a support frame. Two support segments are symmetrically arranged on the outer middle of the extension beams. The two support segments on one side are connected to the quadrant frame, and the two support segments on the other side are connected to the anchor point of the movable mass block. Connecting segments are provided inside the two ends of adjacent extension beams to form closed structural cavities at both ends inside the support frame.

[0014] In one possible implementation, both ends of the support segment and the connecting segment are provided with chamfered structures.

[0015] In one possible implementation, both end faces of the anchor point of the movable mass block along its length are provided with X-direction stop structures, the end faces of the anchor point of the movable mass block away from the support are provided with Y-direction stop structures, and the lower end face of the movable mass block frame and the lower end face of the cover plate are provided with multiple Z-direction stop structures.

[0016] In one possible implementation, a plurality of Z-axis stop structures located in the active mass block frame are respectively disposed at the four corners of the quadrant frame and the four corners of the detection area.

[0017] The beneficial effects of the micromechanical acceleration detection structure for automotive airbags provided by this invention are as follows: Compared with the prior art, the movable mass block frame is located between the base plate and the cover plate. Each of the four corners of the inner side of the movable mass block frame has a quadrant frame. The movable mass block anchor point is connected to the quadrant frame through a support on one side. The lower end of the movable mass block anchor point is fixed to the base plate. Multiple movable comb teeth are provided in the middle of the inner side of the movable mass block frame. Fixed detection comb teeth are provided between adjacent movable comb teeth. The fixed detection comb teeth are fixed to the base plate through fixed comb tooth anchor points. A differential capacitance detection gap is formed between the fixed detection comb teeth and the movable comb teeth. When the micromechanical acceleration detection structure for automotive airbags provided by this invention is applied to an automotive airbag, the acceleration of the vehicle will cause the movable mass block frame to shake, causing the multiple movable comb teeth to shake, thereby changing the differential capacitance detection gap between the movable comb teeth and the fixed detection comb teeth, thus outputting different acceleration signal values. The present invention provides a micromechanical acceleration detection structure for automotive airbags, which adopts a novel frame structure and layout. The four movable mass block anchor points are set in the four quadrant frames, and the large anchor point design ensures the strength of the root of the movable mass block frame while improving the overall impact resistance and stability of the structure, thereby enhancing the reliability of the structure. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a top view of a micromechanical acceleration detection structure for automotive airbags provided in an embodiment of the present invention;

[0020] Figure 2 A front view of a micromechanical acceleration detection structure for automotive airbags provided in an embodiment of the present invention;

[0021] Figure 3This is a schematic diagram of the structure of the active mass block frame provided in an embodiment of the present invention;

[0022] Figure 4 for Figure 1 A magnified view of a section at point A in the middle;

[0023] Figure 5 for Figure 1 A schematic diagram of the supporting structure.

[0024] Explanation of reference numerals in the attached figures:

[0025] 100. Base plate; 200. Movable mass block frame; 210. Quadrant frame; 220. Movable mass block anchor point; 230. Support section; 240. Movable comb teeth; 250. Central partition beam; 260. Side partition beam; 270. Detection frame; 280. Structural frame; 231. Extension beam; 232. Support section; 233. Connecting section; 234. Connecting beam; 300. Fixed detection comb teeth; 310. Fixed comb tooth anchor point; 400. X-direction stop structure; 500. Y-direction stop structure; 600. Z-direction stop structure; 700. Cover plate. Detailed Implementation

[0026] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0027] Please see Figures 1 to 3 This invention provides a micromechanical acceleration detection structure for automotive airbags. The micromechanical acceleration detection structure for automotive airbags includes a base plate 100, a movable mass frame 200, and a cover plate 700. The cover plate 700 is disposed above the base plate 100, and the movable mass frame 200 is horizontally disposed between the base plate 100 and the cover plate 700. Four quadrant frames 210 are respectively provided at the inner corners of the movable mass frame 200. Movable mass anchor points 220 are provided along the length direction within each quadrant frame 210. One side of each movable mass anchor point 220 has a connection to the quadrant frame. The support 230 connected to the frame 210 has its lower end fixed to the substrate 100 via the movable mass block anchor point 220. The middle part of the inner side of the movable mass block frame 200 has multiple movable comb teeth 240. A fixed detection comb tooth 300 is provided between adjacent movable comb teeth 240. A fixed comb tooth anchor point 310 is provided on the fixed detection comb tooth 300. The lower end of the fixed comb tooth anchor point 310 is fixed to the substrate 100. A differential capacitance detection gap is formed between the fixed detection comb tooth 300 and the movable comb tooth 240.

[0028] The present invention provides a micromechanical acceleration detection structure for automotive airbags. Compared with the prior art, the movable mass block frame 200 is located between the base plate 100 and the cover plate 700. The four corners of the inner side of the movable mass block frame 200 are respectively provided with quadrant frames 210. The movable mass block anchor point 220 is connected to the quadrant frame 210 through the support part 230 on one side. The lower end of the movable mass block anchor point 220 is fixed on the base plate 100. The middle part of the inner side of the movable mass block frame 200 is provided with multiple movable comb teeth 240. A fixed detection comb tooth 300 is provided between adjacent movable comb teeth 240. The fixed detection comb tooth 300 is fixed on the base plate 100 through the fixed comb tooth anchor point 310. A differential capacitance detection gap is formed between the fixed detection comb tooth 300 and the movable comb tooth 240. When the micromechanical acceleration detection structure for automotive airbags provided by this invention is applied to automotive airbags, the acceleration of the vehicle causes the movable mass block frame 200 to shake, which in turn causes multiple movable comb teeth 240 to shake. This changes the differential capacitance detection gap between the movable comb teeth 240 and the fixed detection comb teeth 300, thereby outputting different acceleration signal values. The micromechanical acceleration detection structure for automotive airbags provided by this invention adopts a novel frame structure and layout. The four movable mass block anchor points 220 are set within the four quadrant frames 210, and a large anchor point design is used to ensure the strength of the root of the movable mass block frame 200 while improving the overall impact resistance and stability of the structure, thus enhancing its reliability. For some embodiments, please refer to... Figure 1 and Figure 3 The movable mass block frame 200 includes a rectangular frame with a central partition beam 250. The rectangular frame has side partition beams 260 perpendicular to the central partition beam 250 on both sides. The outer areas of the two side partition beams 260 are divided into upper and lower quadrant frames 210 by the central partition beam 250. The inner areas of the two side partition beams 260 are divided into left and right detection areas by the central partition beam 250. Multiple fixed detection comb teeth 300 and multiple movable comb teeth 240 are arranged laterally and spaced longitudinally within the detection area.

[0029] In this embodiment, the movable mass block frame 200 is a closed rectangular frame. A central partition beam 250 and two side partition beams 260 are integrally formed within the rectangular frame. The central partition beam 250 and the two side partition beams 260 respectively divide the internal area of ​​the rectangular frame into four corner quadrant frames 210 and detection areas on both sides of the center. Multiple movable comb teeth 240 are integrally formed within the detection area, dividing the detection area into several detection frames 270. Compared to the traditional single-end fixed method, in this invention, both ends of the movable comb teeth 240 are fixed within the movable mass block frame 200, thus improving the structural strength of the movable comb teeth 240 themselves. This acts like a reinforcing rib for the movable mass block frame 200, enhancing the overall strength and reliability of the entire movable mass block frame 200.

[0030] Each detection frame 270 has two horizontally arranged fixed detection comb teeth 300. Two fixed comb tooth anchor points 310 are provided on opposite sides of the two fixed detection comb teeth 300 within the same detection frame 270. The four fixed comb tooth anchor points 310 within the same detection frame 270 are staggered. The fixed comb tooth anchor point 310 is a rectangular prism structure, with a cross-sectional length that is 1 / 5 the length of the fixed detection comb tooth 300 and a cross-sectional width that is 5 times the width of the fixed detection comb tooth 300. The four fixed comb tooth anchor points 310 of the two fixed detection comb teeth 300 are symmetrically distributed on both sides of the detection frame 270, occupying the space on both sides of the detection frame 270 and a large portion of the area of ​​the detection frame 270. Furthermore, while traditionally the fixed detection comb teeth 300 are fixed at one end, this invention uses double anchor points, improving its strength.

[0031] Please refer to Figure 3 The four side beams, side partition beams 260, and central partition beam 250 of the rectangular frame each have multiple structural frames 280 arranged sequentially along their respective lengths. Each structural frame 280 has a through release hole at both the top and bottom. The structural frame 280 is a structure required for the manufacturing process. The release holes on the structural frame 280 are rectangular holes with rounded inner corners, and the joints are rounded to reduce the risk of damage.

[0032] From the outside, the movable comb teeth 240 and the central partition beam 250 are positioned opposite to the intermediate walls of the two adjacent structural frames 280. The ends of the movable comb teeth 240 are perpendicular to the side beams of the rectangular frame. The movable comb teeth 240 and the intermediate walls of the two adjacent structural frames 280 on the side beams of the rectangular frame are positioned opposite each other and have the same thickness, thus forming a cross-shaped reinforcing structure between the movable comb teeth 240 and the side beams of the rectangular frame.

[0033] Preferably, the corners of the quadrant frame 210, the detection frame 270, and the structural frame 280 are all rounded to reduce the stress at the corners and increase the structural strength.

[0034] In some embodiments, please refer to Figure 5 The support 230 includes two extension beams 231 arranged parallel to each other along the length of the quadrant frame 210. The two ends of the two extension beams 231 are respectively connected to the connecting beams 234. The two extension beams 231 and the two connecting beams 234 at both ends constitute the support frame. Two support sections 232 are symmetrically arranged in the middle of the outer side of the extension beams 231. The two support sections 232 on one side are connected to the quadrant frame 210, and the two support sections 232 on the other side are connected to the movable mass block anchor point 220. The interior of the two ends of the two adjacent extension beams 231 is provided with connecting sections 233 to form a closed structural cavity at both ends inside the support frame.

[0035] In this embodiment, the middle section of the extension beam 231 has two integrally formed support segments 232. Two support segments 232 on one side are connected to the inner wall of the quadrant frame 210, and two support segments 232 on the other side are connected to the side of the movable mass block anchor point 220, thus connecting the movable mass block anchor point 220 to the quadrant frame 210. Preferably, the two ends of the support segments 232 are designed with chamfered structures to reduce stress concentration through a rounded transition, mitigating the impact of sudden acceleration on the movable mass block frame 200 and preventing localized damage to the movable mass block frame 200. Connecting segments 233 are integrally formed inside the two ends of the two extension beams 231, forming closed structural cavities inside the ends. This improves the structural strength of the support frame ends and prevents breakage due to insufficient strength when the support frame undergoes elastic deformation under large impact. Similarly, the two ends of the connecting segments 233 are designed with chamfered structures to reduce stress concentration through a rounded transition.

[0036] In some embodiments, please refer to Figure 2 and Figure 5 The two end faces of the anchor point 220 of the movable mass block along its length are provided with X-direction stop structures 400, and the two sides of the end face of the anchor point 220 of the movable mass block away from the support part 230 are provided with Y-direction stop structures 500. The lower end face of the movable mass block frame 200 and the lower end face of the cover plate 700 are provided with multiple Z-direction stop structures 600.

[0037] In this embodiment, the X-direction stop structure 400, Y-direction stop structure 500, and Z-direction stop structure 600 are all elastic hemispherical structures, which limit the displacement of the structure, reduce the energy at the moment of collision, and improve the reliability of the structure. Each stop structure in each direction has a certain gap with the opposite structural surface, providing a certain buffer space in three-dimensional space. Furthermore, even if displacement occurs in any direction causing the stop structure to contact the opposite structural surface, the elastic hemispherical stop structure can still provide a certain buffer, reducing the possibility of damage to the corresponding structural components due to violent displacement.

[0038] Specifically, the X-direction stop structure 400 and the Y-direction stop structure 500 are in-plane stop structures, which can buffer the in-plane impact of the movable mass block anchor point 220 on the object limiting frame 210 in the X and Y directions. The Z-direction stop structure 600 is an out-of-plane stop structure. The Z-direction stop structure 600 located on the lower end face of the movable mass block frame 200 can buffer the out-of-plane impact of the movable mass block frame 200 on the substrate 100. The Z-direction stop structure 600 located on the lower end face of the cover plate 700 can buffer the out-of-plane impact of the movable mass block frame 200 on the lower end face of the cover plate 700.

[0039] Multiple Z-axis stop structures 600 are located on the lower end face of the movable mass block frame 200, respectively positioned at the four corners of the quadrant frame 210 and the four corners of the detection area. This ensures that the multiple Z-axis stop structures 600 cover most of the upper and lower end faces of the movable mass block frame 200. Furthermore, their distribution at the four corners of the quadrant frame 210 and the four corners of the detection area provides buffering, particularly for the two critical areas of the movable mass block frame 200, effectively protecting against impacts on the movable mass block anchor point 220 and the corresponding comb teeth caused by Z-axis displacement.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A micromechanical acceleration detection structure for automotive airbags, characterized in that, It includes a substrate (100), a movable mass block frame (200), and a cover plate (700), wherein the cover plate (700) is disposed above the substrate (100), and the movable mass block frame (200) is horizontally disposed between the substrate (100) and the cover plate (700). The inner corner of the movable mass block frame (200) is provided with four quadrant frames (210), and movable mass block anchor points (220) are provided in the quadrant frames (210) along the length direction. A support part (230) connected to the quadrant frame (210) is provided on one side of the movable mass block anchor point (220), and the lower end of the movable mass block anchor point (220) is fixed on the base plate (100). The inner middle of the movable mass block frame (200) has multiple movable comb teeth (240), and a fixed detection comb tooth (300) is provided between adjacent movable comb teeth (240). The fixed detection comb tooth (300) is provided with a fixed comb tooth anchor point (310). The lower end of the fixed comb tooth anchor point (310) is fixed on the substrate (100). A differential capacitance detection gap is formed between the fixed detection comb tooth (300) and the movable comb tooth (240). The movable mass block frame (200) includes a rectangular frame with a central partition beam (250). The rectangular frame has side partition beams (260) perpendicular to the central partition beam (250) on both sides. The outer regions of the two side partition beams (260) are divided into upper and lower quadrant frames (210) by the central partition beam (250). The inner regions of the two side partition beams (260) are divided into left and right detection areas by the central partition beam (250). Multiple fixed detection comb teeth (300) and multiple movable comb teeth (240) are arranged laterally and spaced longitudinally within the detection area. The detection area is divided into several detection frames (270) by multiple movable comb teeth (240). Two fixed detection comb teeth (300) are arranged horizontally in each detection frame (270). Two fixed comb tooth anchor points (310) are provided on the opposite sides of the two fixed detection comb teeth (300) in the same detection frame (270). The four fixed comb tooth anchor points (310) in the same detection frame (270) are staggered.

2. The micromechanical acceleration detection structure for automotive airbags as described in claim 1, characterized in that, The four side beams of the rectangular frame, the side partition beam (260) and the middle partition beam (250) are each provided with a plurality of structural frames (280) arranged sequentially along their respective length directions, and the structural frames (280) are provided with through release holes at the upper and lower ends.

3. The micromechanical acceleration detection structure for automotive airbags as described in claim 2, characterized in that, The movable comb teeth (240) and the central partition beam (250) are arranged opposite to the middle walls of the two adjacent structural frames (280).

4. The micromechanical acceleration detection structure for automotive airbags as described in claim 2, characterized in that, The corners of the quadrant frame (210), the detection frame (270), and the structure frame (280) are all rounded.

5. The micromechanical acceleration detection structure for automotive airbags as described in claim 1, characterized in that, The support (230) includes two extension beams (231) arranged parallel to each other along the length of the quadrant frame (210). The two ends of the two extension beams (231) are respectively connected to connecting beams (234). The two extension beams (231) and the two connecting beams (234) at both ends constitute a support frame. Two support sections (232) are symmetrically arranged in the middle of the outer side of the extension beams (231). The two support sections (232) on one side are connected to the quadrant frame (210), and the two support sections (232) on the other side are connected to the movable mass block anchor point (220). The two ends of the two adjacent extension beams (231) are provided with connecting sections (233) to form closed structural cavities at both ends inside the support frame.

6. The micromechanical acceleration detection structure for automotive airbags as described in claim 5, characterized in that, Both ends of the support section (232) and the connecting section (233) are provided with chamfered structures.

7. The micromechanical acceleration detection structure for automotive airbags as described in claim 1, characterized in that, The two end faces of the movable mass block anchor point (220) along its length are provided with X-direction stop structures (400), and the two sides of the end face of the movable mass block anchor point (220) away from the support part (230) are provided with Y-direction stop structures (500). The lower end face of the movable mass block frame (200) and the lower end face of the cover plate (700) are provided with multiple Z-direction stop structures (600).

8. The micromechanical acceleration detection structure for automotive airbags as described in claim 7, characterized in that, The plurality of Z-direction stop structures (600) located in the active mass block frame (200) are respectively disposed at the four corners of the quadrant frame (210) and the four corners of the detection area.

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