MEMS inertial sensor

Abstract

The MEMS inertial sensor comprises a shell, a top cover and connecting pieces, the top cover is fixedly connected to the upper portion of the shell, the connecting pieces are connected to the four corners of the top face of the top cover in an inserted mode, and the connecting pieces are in threaded connection with the four corners of the shell; the bottom of the inner side of the shell is fixedly connected with a plate body, the plate body is provided with a capacitor, the top surface of the capacitor is connected with elastic beams, a mass block is fixedly connected between the elastic beams, and the mass block is movably connected to the surface of the plate body. The sensor has the advantages that the sensor is assembled with the panel through the mounting lugs, the screws and the panel, the mounting lugs are improved, the top openings of the preformed holes of the mounting lugs are changed to be conical, the mounting lugs are improved to be the magnetic attraction-insertion connection composite lugs, and the guide magnetic rings are embedded into the top openings of the preformed holes, so that magnetic attraction and guide can be performed when small screws are mounted; the sensor is more convenient to mount, the mounting time consumption is greatly reduced, and the mounting tolerance is reduced.

Description

Technical Field

[0001] This utility model relates to the field of inertial sensor technology, and in particular to a MEMS inertial sensor. Background Technology

[0002] Microelectromechanical systems (MEMS) inertial sensors, especially accelerometers, have been widely used in consumer electronics, automotive electronics, industrial control, navigation and positioning, and other fields due to their advantages such as small size, low cost, low power consumption, and high reliability. Their core working principle is typically based on detecting the displacement change of an inertial sensitive mass under external acceleration and converting it into a measurable electrical signal through effects such as capacitance and piezoresistive forces.

[0003] Existing MEMS inertial sensors typically include a sealed housing structure (such as a metal or ceramic housing with a top cover) to protect the internal delicate MEMS sensing structure and processing chip (ASIC) from environmental factors (such as humidity and particulate matter) and external interference. The internal structure mainly includes capacitors (usually composed of moving and fixed electrodes) fixed to a substrate, an inertial mass block connected between the capacitors, and elastic beams (such as folding beams) supporting the mass block. When acceleration is applied to the sensor, the mass block, due to inertia, overcomes the restoring force of the elastic beam, resulting in a slight displacement. This causes a change in the distance between the moving and fixed electrodes, thereby causing a change in capacitance. This change in capacitance is detected by the integrated MEMS chip and converted into a voltage signal, which is then output to an external system via leads.

[0004] However, despite the compact structure of MEMS sensors, their practical installation and application still present some challenges, especially in scenarios involving miniaturization and high-density integration:

[0005] High-precision installation alignment is challenging: Traditional installation methods typically involve creating through holes in the sensor housing's mounting ears (or bosses) and using micro-bolts or screws to secure the sensor to the mounting panel. For micro-MEMS sensors, the mounting ears themselves are very small, and the pre-drilled mounting holes are only at the sub-millimeter level. This makes it extremely difficult to precisely align and insert the tip of the tiny screw into the narrow mounting hole during assembly. Operators need exceptional patience and finesse, often requiring the use of magnifying glasses or precision clamps, resulting in low installation efficiency and lengthy installation times. Utility Model Content

[0006] The purpose of this invention is to at least solve one of the aforementioned technical defects.

[0007] Therefore, one objective of this invention is to propose a MEMS inertial sensor to solve the problems mentioned in the background art and overcome the shortcomings of the existing technology.

[0008] To achieve the above objectives, one embodiment of the present invention provides a MEMS inertial sensor, including a housing, a top cover, and connectors. The top cover is fixedly connected to the top of the housing, and connectors are inserted into the four corners of the top surface of the top cover. The connectors are threadedly connected to the four corners of the housing.

[0009] A plate is fixedly connected to the bottom of the inner side of the outer shell. A capacitor is installed on the plate. An elastic beam is connected to the top surface of the capacitor. A mass block is fixedly connected between the elastic beams. The mass block is movably connected to the surface of the plate.

[0010] Several movable electrodes are fixedly connected to both sides of the mass block, and a fixed electrode is fixedly connected to the top surface of the plate.

[0011] The output terminal of the capacitor is unidirectionally connected to a MEMS chip, and the output terminal of the MEMS chip is unidirectionally connected to an output line, which passes through the outer casing.

[0012] The sides and bottom of the outer casing are covered with a shielding layer, and the surface of the top cover is covered with a shielding layer.

[0013] Mounting ears are fixedly connected to both sides of the outer shell. The mounting ears are provided with reserved holes. The inner diameter of the top opening of the reserved holes gradually decreases from top to bottom. A guide magnetic ring is fixedly connected to the top opening of the reserved holes.

[0014] Preferably, the outer shell and top cover are made of aluminum alloy, and the connecting parts are specifically cross screws.

[0015] The above technical solution employs a mass block typically made of silicon, which acts as an inertial sensing element, displacing under acceleration. Elastic beams at both ends of the mass block support it and provide restoring force to limit the displacement range. Several movable electrodes are located on both sides of the mass block, while the fixed electrodes are stationary electrodes connected to the substrate. When the sensor is subjected to acceleration, the mass block displaces due to inertia, causing a change in the distance between the movable and fixed electrodes. This displacement changes the electrode distance d, and the capacitance C∝1 / d. This capacitance change is converted into a voltage signal, which is then output through an output line, thus achieving acceleration sensing.

[0016] Preferably, in any of the above embodiments, the plate is bonded to the inside of the outer casing, and the mass block moves linearly on an axis fixed to the top surface of the plate. Traditional sensors, which are mounted with bolts, require high precision in hole positioning, and the screws used for installation are relatively small.

[0017] The above technical solution is adopted: This sensor is assembled with a panel by mounting ears, screws, and a pre-drilled hole. The mounting ears are improved by changing the top opening of the pre-drilled hole to a conical shape. The mounting ears are improved to be magnetic-plug composite ears, and a guide magnetic ring is embedded in the top opening of the pre-drilled hole. This allows for magnetic attraction and guidance when installing small screws, making it easier to install the sensor, greatly reducing installation time, and reducing installation tolerance.

[0018] The matching outer shell and top cover are made of aluminum alloy, and the surface of the outer shell and top cover is covered with a metal shielding layer to shield the magnetic field of the magnet and prevent the magnet from affecting the performance of the sensor.

[0019] Preferably, in any of the above schemes, the distance between the active electrode and the fixed electrode is variable, and the MEMS chip is fixed to the board by pin welding.

[0020] The above technical solution is adopted. The structure of this device consists of: Anti-interference main body: aluminum alloy shell and top cover are locked together by cross connector (torque 1.5 N·m), and the inner and outer surfaces are covered with copper-nickel alloy shielding layer (thickness 50 μm), with shielding effectiveness ≥60dB.

[0021] An alumina plate is bonded to the bottom inner side of the outer casing, and a capacitor is integrated on the top surface of the plate. A monocrystalline silicon mass block is suspended on the surface of the plate by elastic beams at both ends (elasticity coefficient 2 N / m). Movable electrodes (tooth width 25 μm) are set on both sides of the mass block, forming multiple capacitor pairs with the fixed electrodes on the plate.

[0022] The quick-installation system has mounting ears (304 stainless steel) welded to both sides of the outer casing, with a tapered pre-drilled hole in the center of each mounting ear.

[0023] Innovative guiding structure: A neodymium iron boron guide magnetic ring is embedded in the top of the reserved hole and fixed to the edge of the hole by laser micro-welding, and the surface is nickel-plated for corrosion protection.

[0024] The inner diameter of the guide magnetic ring is smoothly connected to the tapered surface of the reserved hole.

[0025] The signal processing unit, a MEMS chip, is connected to a capacitor via gold wire bonding, converting changes in capacitance into voltage signals. The output line (silver-plated copper wire) passes through a shielding layer, and the outlet is filled with conductive silicone to achieve electromagnetic sealing.

[0026] Preferably, in any of the above solutions, the shielding layer is made of metal, and the mounting ear is welded to the outer shell.

[0027] Preferably, in any of the above schemes, the guide magnetic ring is a neodymium iron boron magnet, and the guide magnetic ring is embedded in the top opening of the reserved hole.

[0028] Compared with the prior art, the advantages and beneficial effects of this utility model are as follows:

[0029] This MEMS inertial sensor is assembled with a panel using mounting ears, screws, and a pre-drilled hole. The mounting ears have been improved by changing the top opening of the pre-drilled hole to a tapered shape. The mounting ears have been improved to be a magnetic-plug composite ear, and a guide magnetic ring is embedded in the top opening of the pre-drilled hole. This allows for magnetic attraction and guidance when installing small screws, making the sensor easier to install, greatly reducing installation time, and also reducing installation tolerances.

[0030] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0031] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0032] Figure 1 This is a first-view structural schematic diagram of the present invention;

[0033] Figure 2 This is a structural schematic diagram of the present invention from a second perspective;

[0034] Figure 3 This is a schematic diagram of the structure at the reserved hole of this utility model;

[0035] Figure 4 This is a schematic diagram of the internal structure of the outer shell of this utility model.

[0036] In the diagram: 1-outer shell, 2-top cover, 3-connector, 4-plate, 5-elastic beam, 6-mass block, 7-moving electrode, 8-fixed electrode, 9-capacitor, 10-MEMS chip, 11-output line, 12-shielding layer, 13-mounting ear, 14-pre-drilled hole, 15-guide magnetic ring. Detailed Implementation

[0037] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0038] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0039] like Figure 1-4 As shown, this MEMS inertial sensor includes a housing 1, a top cover 2, and connectors 3. The top cover 2 is fixedly connected to the top of the housing 1, and connectors 3 are inserted into the four corners of the top surface of the top cover 2. The connectors 3 are threadedly connected to the four corners of the housing 1.

[0040] A plate 4 is fixedly connected to the bottom of the inner side of the outer shell 1. A capacitor 9 is installed on the plate 4. An elastic beam 5 is connected to the top surface of the capacitor 9. A mass block 6 is fixedly connected between the elastic beams 5. The mass block 6 is movably connected to the surface of the plate 4.

[0041] Several movable electrodes 7 are fixedly connected to both sides of the mass block 6, and a fixed electrode 8 is fixedly connected to the top surface of the plate 4.

[0042] The output terminal of capacitor 9 is unidirectionally connected to MEMS chip 10, and the output terminal of MEMS chip 10 is unidirectionally connected to output line 11, which passes through housing 1.

[0043] The sides and bottom of the outer casing 1 are covered with a shielding layer 12, and the surface of the top cover 2 is covered with a shielding layer 12.

[0044] Mounting ears 13 are fixedly connected to both sides of the outer shell 1. The mounting ears 13 are provided with reserved holes 14. The inner diameter of the top opening of the reserved hole 14 gradually decreases from top to bottom. A guide magnetic ring 15 is fixedly connected to the top opening of the reserved hole 14.

[0045] Example 1: The outer shell 1 and top cover 2 are made of aluminum alloy, and the connecting part 3 is specifically a cross-head screw. The plate 4 is bonded to the inside of the outer shell 1, and the mass block 6 moves linearly on an axis fixed on the top surface of the plate 4. Traditional sensors are installed with bolts, which require high hole precision, and the screws used for installation are relatively small. The distance between the movable electrode 7 and the fixed electrode 8 is variable, and the MEMS chip 10 is fixed to the plate 4 by pin soldering. The shielding layer 12 is made of metal, and the mounting ear 13 is soldered to the outer shell 1. The guide magnetic ring 15 is specifically a neodymium iron boron magnet, and the guide magnetic ring 15 is embedded in the top opening of the reserved hole 14.

[0046] Example 2: The outer shell 1 and top cover 2 are made of aluminum alloy. A metal shielding layer 12 covers the surfaces of the outer shell 1 and top cover 2 to shield the magnetic field of the magnet and prevent the magnet from affecting the performance of the sensor. The device structure consists of: an anti-interference main body: the aluminum alloy outer shell 1 and top cover 2 are locked together by a cross connector 3 (torque 1.5 N·m), with a copper-nickel alloy shielding layer 12 (thickness 50 μm) covering both inner and outer surfaces, providing a shielding effectiveness ≥60 dB.

[0047] An alumina plate 4 is bonded to the bottom inner side of the outer casing 1, and a capacitor 9 is integrated on the top surface of the plate 4. A monocrystalline silicon mass block 6 is suspended on the surface of the plate 4 by elastic beams 5 at both ends (elasticity coefficient 2 N / m). Movable electrodes 7 (tooth width 25 μm) are set on both sides of the mass block 6, forming multiple capacitor pairs with the fixed electrodes 8 on the plate 4.

[0048] The quick-installation system has mounting ears 13 (304 stainless steel) welded to both sides of the outer casing 1, and a tapered pre-drilled hole 14 in the center of the mounting ears 13.

[0049] Innovative guiding structure: A neodymium iron boron guide magnetic ring 15 is embedded in the top opening of the pre-drilled hole 14 and fixed to the edge of the hole by laser micro-welding. The surface is nickel-plated for corrosion protection.

[0050] The inner diameter of the guide magnetic ring 15 is smoothly connected to the conical surface of the reserved hole 14.

[0051] The signal processing unit, MEMS chip 10, is connected to capacitor 9 via gold wire bonding, converting capacitance changes into voltage signals. Output line 11 (silver-plated copper wire) passes through shielding layer 12, and the outlet is filled with conductive silicone to achieve electromagnetic sealing.

[0052] The working principle of this utility model is as follows:

[0053] The mass block 6, typically made of silicon, acts as an inertial sensing element, displacing under acceleration. Elastic beams 5 support the mass block 6 at both ends, providing restoring force to limit the displacement range. Several movable electrodes 7 are located on both sides of the mass block 6, while the fixed electrodes 8 are stationary electrodes connected to the substrate. When the sensor is subjected to acceleration, the mass block 6 displaces due to inertia, causing a change in the distance between the movable electrodes 7 and the fixed electrodes 8. This displacement changes the electrode spacing d, and the capacitance C ∝ 1 / d. This capacitance change is converted into a voltage signal, which is then output through the output line 11, thus achieving acceleration sensing.

[0054] Compared with the prior art, the present invention has the following advantages:

[0055] This MEMS inertial sensor is assembled with a mounting ear 13, screws, and a panel. The mounting ear 13 has been improved by changing the top opening of the reserved hole 14 of the mounting ear 13 to a conical shape. The mounting ear 13 has been improved into a magnetic attraction-plugging composite ear, and a guide magnetic ring 15 is embedded in the top opening of the reserved hole 14. It can magnetically attract and guide the sensor when installing small screws, making the installation of this sensor easier, greatly reducing the installation time, and reducing the installation tolerance.

Claims

1. A MEMS inertial sensor, characterized in that, Includes an outer shell (1), a top cover (2), and connectors (3). The top cover (2) is fixedly connected to the top of the outer shell (1). Connectors (3) are inserted into the four corners of the top surface of the top cover (2). The connectors (3) are threaded to the four corners of the outer shell (1). A plate (4) is fixedly connected to the bottom of the inner side of the outer shell (1). A capacitor (9) is installed on the plate (4). An elastic beam (5) is connected to the top surface of the capacitor (9). A mass block (6) is fixedly connected between the elastic beams (5). The mass block (6) is movably connected to the surface of the plate (4). Several movable electrodes (7) are fixedly connected to both sides of the mass block (6), and a fixed electrode (8) is fixedly connected to the top surface of the plate (4). The output terminal of the capacitor (9) is unidirectionally connected to the MEMS chip (10), and the output terminal of the MEMS chip (10) is unidirectionally connected to the output line (11), which passes through the outer shell (1). The sides and bottom of the outer shell (1) are covered with a shielding layer (12), and the surface of the top cover (2) is covered with a shielding layer (12). The outer shell (1) is fixedly connected to two sides with mounting ears (13), and the mounting ears (13) are provided with reserved holes (14). The inner diameter of the top opening of the reserved hole (14) gradually decreases from top to bottom, and a guide magnetic ring (15) is fixedly connected to the top opening of the reserved hole (14).

2. The MEMS inertial sensor as described in claim 1, characterized in that: The outer shell (1) and top cover (2) are made of aluminum alloy, and the connector (3) is specifically a cross screw.

3. A MEMS inertial sensor as described in claim 2, characterized in that: The plate (4) is bonded to the inside of the shell (1), and the mass block (6) moves linearly on an axis fixed on the top surface of the plate (4).

4. A MEMS inertial sensor as described in claim 3, characterized in that: The distance between the active electrode (7) and the fixed electrode (8) is variable, and the MEMS chip (10) and the plate (4) are fixed by pin welding.

5. A MEMS inertial sensor as described in claim 4, characterized in that: The shielding layer (12) is made of metal, and the mounting ear (13) is welded to the outer shell (1).

6. A MEMS inertial sensor as described in claim 5, characterized in that: The guide magnetic ring (15) is specifically a neodymium iron boron magnet, and the guide magnetic ring (15) is embedded in the top opening of the reserved hole (14).

Images