A MEMS inertial measurement device capable of withstanding large overloads

Abstract

The present invention discloses a MEMS inertial measurement device capable of resisting large overload, comprising a base and a bracket assembly, a vibration-damping pad and a supporting screw located on the base, wherein the bracket assembly comprises a bracket, a processing board, a chip and a potting glue layer, wherein the processing board is fixed on the bracket and connected to a plurality of chips, and the potting glue layer is filled in the gap between the bracket and the plurality of chips so that each chip is suspended and mounted on the base; the supporting screws are sequentially passed through the bracket and the vibration-damping pad and connected to the base, and the vibration-damping pad is arranged at the contact position between the base and the bracket. The purpose of the MEMS inertial measurement device capable of resisting large overload is to solve the problem of insufficient overload resistance of existing MEMS inertial measurement devices.

Description

Technical Field

[0001] The invention relates to the technical field of MEMS inertial measurement devices, and in particular to a MEMS inertial measurement device capable of resisting large overload. Background Art

[0002] Inertial measurement devices and inertial measurement systems based on micro-electromechanical systems (MEMS) are the best choice to meet these requirements under specific accuracy requirements. Compared with traditional inertial measurement components, they have unprecedented small size and weight, high reliability, long life, etc. Although MEMS inertial measurement devices have strong resistance to vibration and shock, they still cannot be directly used in high overload environments.

[0003] In view of this, those skilled in the art are in urgent need of providing a MEMS inertial measurement device that can withstand large overloads to solve the above problems. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The purpose of the present invention is to provide a MEMS inertial measurement device capable of resisting large overload, so as to solve the technical problem that the existing MEMS inertial measurement device has insufficient overload resistance.

[0006] (II) Technical solution

[0007] The present invention provides a MEMS inertial measurement device capable of resisting large overload, comprising a base and a bracket assembly, a vibration-damping pad and a supporting screw located on the base, wherein the bracket assembly comprises a bracket, a processing board, a chip and a potting adhesive layer, wherein the processing board is fixed on the bracket and connected to a plurality of the chips; the potting adhesive layer is filled in the gap between the bracket and the plurality of the chips so that each of the chips is suspended and installed on the base, the supporting screw is sequentially penetrated through the bracket and the vibration-damping pad and connected to the base, and the vibration-damping pad is arranged at the contact position between the base and the bracket.

[0008] Furthermore, the bracket is in the shape of a hollow polygonal prism, the plurality of chips are located on the outside of the bracket, the processing board is fixed to the top opening of the bracket, and at least one corner of the bracket is connected to the base through the vibration-damping pad.

[0009] Furthermore, the plurality of chips include an accelerometer chip and a gyroscope chip, the accelerometer chip and the gyroscope chip are respectively fixed on corresponding circuit boards, and the circuit boards are connected to the processing board.

[0010] Furthermore, the circuit board is connected to the processing board in a floating manner.

[0011] Furthermore, there are three accelerometer chips and three gyroscope chips.

[0012] Furthermore, the support screw is screwed to the base and is used to adjust the elasticity of the vibration damping pad.

[0013] Furthermore, the vibration damping pad includes a first vibration damping part, a connecting part and a second vibration damping part connected in sequence, the first vibration damping part and the second vibration damping part are symmetrically arranged at both ends of the connecting part, and the horizontal plane where the center of gravity of the bracket assembly is located overlaps with the horizontal plane where the center of gravity of the vibration damping pad is located.

[0014] Furthermore, the four corner portions are respectively located at four corners of the bracket, the corner portions are boss-shaped, and the first vibration-damping portion and the second vibration-damping portion are respectively located on the upper and lower end surfaces of the corner portions.

[0015] Furthermore, a line connecting an intersection point between two spaced-apart angular portions and a line connecting the center of gravity of the bracket assembly is perpendicular to the base.

[0016] Furthermore, the vibration damping pad is made of super elastic rubber material.

[0017] Furthermore, the potting glue layer is made of silicone rubber.

[0018] (III) Beneficial effects

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The MEMS inertial measurement device capable of resisting large overloads provided by the present invention realizes vibration reduction of the bracket assembly through the vibration reduction pad, and realizes that each chip moves slightly with the potting layer as a whole under impact state through the potting layer, thereby protecting the electronic components. Through the above two-stage vibration reduction method, the ability to resist large overloads is improved. In an environment with large overloads outside, the internal components of the MEMS inertial measurement device are effectively protected, so that sensitive components can work in a tolerable mechanical environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a MEMS inertial measurement device capable of withstanding large overloads provided by an embodiment of the present invention;

[0022] Figure 2 It is a structural explosion diagram of a MEMS inertial measurement device capable of withstanding large overloads provided by an embodiment of the present invention;

[0023] Figure 3 is a performance curve diagram of a MEMS inertial measurement device capable of withstanding large overloads provided by an embodiment of the present invention;

[0024] Figure 4This is a shock test diagram of a MEMS inertial measurement device capable of withstanding large overloads provided by an embodiment of the present invention.

[0025] In the figure:

[0026] 1 base; 2 vibration damping pad; 201 first vibration damping part; 202 connecting part; 203 second vibration damping part; 3 supporting screw; 4 bracket; 401 corner part; 5 processing board; 6 potting glue layer; 7 accelerometer chip; 8 gyroscope chip; 9 circuit board; A ideal waveform upper limit curve; B channel 2 feedback curve; C ideal waveform curve; D ideal waveform lower limit curve; E channel 1 feedback curve. DETAILED DESCRIPTION

[0027] The following is a detailed description of the specific implementation of the present invention in conjunction with the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0028] It should be noted that, in order to clearly explain the content of the present invention, the present invention specifically cites multiple embodiments to further illustrate different implementations of the present invention, wherein the multiple embodiments are enumerated rather than exhaustive. In addition, for the sake of brevity of explanation, the contents mentioned in the previous embodiments are often omitted in the subsequent embodiments. Therefore, the contents not mentioned in the subsequent embodiments can refer to the previous embodiments accordingly.

[0029] In order to solve the problems of vibration reduction and installation stress, existing MEMS inertial measurement components have adopted different vibration reduction structures. In summary, there are basically three vibration reduction methods, namely:

[0030] 1) Use PCB flexible board and install and fix it by gluing;

[0031] 2) Use ordinary PCB boards, make grooves in the PCB boards, reduce the connection area between the PCB board fixing area and the MEMS chip installation area, and thus minimize the impact of the PCB board installation stress on the MEMS chip;

[0032] 3) Use vibration-damping pads to reduce vibration on the bracket on which the MEMS chip is mounted.

[0033] The above three structural forms focus on solving the vibration reduction and assembly stress problems of MEMS inertial measurement components. From the perspective of vibration reduction indicators, they cannot solve the problem of MEMS inertial measurement components' ability to withstand an overload of about 20,000g.

[0034] According to an embodiment of the present invention, a MEMS inertial measurement device capable of withstanding large overload is provided, such as Figure 1-2As shown, it includes a base 1 and a bracket assembly, a vibration-damping pad 2 and a supporting screw 3 located on the base 1. The bracket assembly includes a bracket 4, a processing board 5, a chip and a potting glue layer 6. The processing board 5 is fixed on the bracket 4 and connected to multiple chips; the potting glue layer 6 is filled in the gap between the bracket 4 and the multiple chips so that each chip is suspended and installed on the base 1. The supporting screw 3 is sequentially penetrated through the bracket 4 and the vibration-damping pad 2 and connected to the base 1. The vibration-damping pad 2 is arranged at the contact position between the base 1 and the bracket 4.

[0035] In the above embodiment, the weapon system will generate a huge impact at the moment of firing, and the base 1 and the bracket 4 are in flexible contact through the vibration-damping pad 2, and the support screw 3 passes through the vibration-damping pad 2 to contact the base 1. The stiffness of the vibration-damping pad 2 is adjusted by adjusting the length of the support screw 3, so that the inertial measurement device can achieve the effect of isolating the impact, and the working environment of the measurement component is greatly improved. However, it is still not guaranteed that all devices will survive and work reliably after a huge impact. Therefore, in order to further improve the impact resistance of electronic devices, the inside of the measurement system is potted with a potting layer 6 made of special silicone rubber. It has also been fully proved in many harsh mechanical tests that only potted electronic devices can work reliably.

[0036] In some optional embodiments, such as Figure 1-2 As shown, the bracket 4 is a hollow polygonal prism, multiple chips are located on the outside of the bracket 4, the processing board 5 is fixed to the top opening of the bracket 4, and at least one corner 401 of the bracket 4 is connected to the base 1 through the vibration-damping pad 2.

[0037] Specifically, Figure 2 As shown, the bracket 4 is a quadrangular prism, so it has four corner portions 401. A mounting hole can be opened at each corner portion 401 for installing the vibration-damping pad 2. The support screws 3 are passed through the mounting holes to fix the vibration-damping pad 2 between the bracket 4 and the base 1 to prevent direct contact between the base 1 and the bracket 4 during a large overload impact, thereby achieving a vibration reduction effect.

[0038] In some optional embodiments, the plurality of chips include an accelerometer chip 7 and a gyroscope chip 8, and the accelerometer chip 7 and the gyroscope chip 8 are respectively fixed on corresponding circuit boards 9, and the circuit boards 9 are connected to the processing board 5. The accelerometer chip 7 and the gyroscope chip 8 are mounted on independent circuit boards 9, and each circuit board 9 is connected by wires for information transmission.

[0039] In some optional embodiments, the circuit board 9 is connected to the processing board 5 in a suspended manner. Specifically, since the circuit board 9 is fastened to the mounting bracket with screws, when the temperature changes, a slight deformation will occur in the center of the circuit board 9. This deformation will cause stress in the MEMS chip, causing the sensitive device to drift in zero position with temperature. In the scheme, the mounting screws of the circuit board are eliminated, and the circuit board 9 with the MEMS chip mounted is directly bonded to the bracket 4 with a special adhesive. When the temperature changes, the circuit board 9 will stretch freely without distortion, avoiding installation stress problems caused by temperature influences, and solving complex stress problems. The circuit board 9 is separated from the rigid connection state with the shell, and the circuit board 9 is filled with a potting glue layer 6. Under impact, each circuit board 9 moves slightly as a whole with the potting glue layer 6, thereby protecting electronic components.

[0040] In some optional embodiments, there are three accelerometer chips 7 and three gyroscope chips 8. Specifically, in view of the application characteristics of MEMS inertial devices, three accelerometer chips 7 and three gyroscope chips 8 are used in the design.

[0041] In some optional embodiments, the support screw 3 is screwed to the base 1 and is used to adjust the elasticity of the vibration damping pad 2. Specifically, a threaded hole adapted to the support screw 3 can be provided at a corresponding position on the base 1, and when the vibration damping pad 2 needs to be squeezed, the support screw 3 can be tightened; when the vibration damping pad 2 needs to be released, the support screw 3 can be loosened. Thus, the elasticity of the vibration damping pad 2 can be freely adjusted, and the vibration damping pad 2 can be squeezed or released according to actual needs.

[0042] In some optional embodiments, the vibration damping pad 2 includes a first vibration damping portion 201, a connecting portion 202 and a second vibration damping portion 203 connected in sequence, the first vibration damping portion 201 and the second vibration damping portion 202 are symmetrically arranged at both ends of the connecting portion 203, and the horizontal plane where the center of gravity of the bracket assembly is located overlaps with the horizontal plane where the center of gravity of the vibration damping pad 2 is located.

[0043] In the above embodiment, the center of gravity of the vibration-damping pad 2 installed at the corner portion 401 is in the same plane as the center of gravity of the bracket assembly and is evenly distributed along the center of gravity plane, which can avoid disturbances, torsion and other interference modes during operation as much as possible, and ensure a good working environment for sensitive devices. In this way, it can be ensured that the vibration-damping effect of the vibration-damping pad 2 reaches the best state, and at the same time, the first vibration-damping portion 201 and the second vibration-damping portion 202 can realize two-way vibration reduction at the top and bottom, thereby improving the vibration-damping effect.

[0044] In some optional embodiments, such as Figure 1-2 As shown, four corner portions 401 are respectively located at four corners of the bracket 4 , the corner portions 401 are boss-shaped, and the first vibration-damping portion 201 and the second vibration-damping portion 202 are respectively located on the upper and lower end surfaces of the corner portions 401 .

[0045] Specifically, there is no specific limitation on the number of the corner portions 401 of the bracket 4. Of course, the number of the corner portions 401 is actually determined based on the structural characteristics of the bracket 4 itself. Generally speaking, at least three corner portions 401 are required for the bracket 4 to support the base 1 to achieve a stable support effect. Figure 1 The bracket 4 shown is similar to a cube and therefore has four corner portions 401. The bracket assembly is supported on the base 1 after the vibration-damping pad 2 is installed through mounting holes evenly distributed therein. The boss-shaped corner portions 401 facilitate the installation of the support screws 3; the first vibration-damping portion 201 and the second vibration-damping portion 202 are respectively located on the upper and lower end surfaces of the corner portion 401 to better achieve the vibration-damping effect.

[0046] In some optional embodiments, the intersection of the line connecting two spaced corner portions 401 and the line connecting the center of gravity of the bracket assembly is perpendicular to the base 1 .

[0047] Specifically, such a configuration can ensure that the corner portions 401 are symmetrically distributed along the center of gravity of the bracket assembly, thereby ensuring that the supporting effect of the bracket 4 is better.

[0048] In some optional embodiments, the vibration damping pad 2 is made of superelastic rubber. Among them, the rubber vibration damping pad has a relatively simple structure, stable reliability and good economy. The superelastic property has low modulus and high ductility characteristics, nonlinear stress-strain curve and almost incompressibility.

[0049] In some optional embodiments, the potting glue layer 6 is made of silicone rubber. The potting glue is a specially configured two-component silicone rubber with good insulation performance, good fluidity and excellent bonding performance. In order to enhance thermal conductivity, the proportion of aluminum oxide is increased. The mixture is fully stirred and vacuumed at room temperature, and cured at room temperature. After curing, the mixture has excellent vibration reduction and impact resistance properties, and is assembled and adjusted after potting and shaping.

[0050] The inertial measurement device of the present invention adopts a two-stage vibration reduction method, such as Figure 4 As shown in the figure, the inertial measurement device has the ability to withstand a large overload of 20,000g. The first-level vibration reduction adopts the vibration reduction pad method, which provides four-point vibration reduction support on the center of gravity plane of the vibration-damped load, which not only enables the vibration load to absorb large energy overloads, but also allows the vibration-damped body to maintain a certain accuracy to a certain extent. The second-level vibration reduction is to suspend the MEMS device on the vibration-damped body by using a special potting glue, which not only solves the working stress problem, but also improves the vibration resistance of the MEMS device.

[0051] in, Figure 4 The data of each point are shown in Table 1 below:

[0052] Through the errors of acceleration measurement value and pulse width measurement value between channel 1 (input impact of inertial measurement device), channel 2 (output impact of detected sensor) and ideal waveform, it can be seen that the highest point of feedback curve E of channel 1 is infinitely close to the highest point of ideal waveform curve C, but will not exceed it. When the time reaches 0.180ms, all five curves reach the highest point; at the same time, ideal waveform curve C is always between the ideal waveform upper limit curve A and the ideal waveform lower limit curve D. The acceleration value corresponding to the highest point of feedback curve B of channel 2 is close to half of the highest point of feedback curve E of channel 1. It can be seen that the vibration reduction effect for large overload impact is almost half of the overload impact force, and the shock reduction effect is very obvious.

[0053] Table 1 Comparison before and after vibration reduction

[0054]

[0055] This inertial measurement device solves the problem of MEMS inertial system's ability to withstand large overloads. It enables the product to adapt to harsh mechanical environments. After taking vibration reduction measures, the effect is obvious under various impact conditions. Figure 3 It can be found that after taking vibration reduction measures, as the tolerable force continues to increase, the vibration reduction efficiency gradually decreases. The technical indicators of this MEMS inertial system are comparable to those of the same type of inertial group, and it has stronger adaptability to the environment. Compared with other MEMS inertial systems, it has the advantages of small size, high reliability, and strong overload resistance.

[0056] Although the invention can be extended in various forms of modification and substitution, some specific implementation examples are listed in the specification and described in detail. It should be understood that the inventor's starting point is not to limit the invention to the specific embodiments described. On the contrary, the inventor's starting point is to protect all improvements, equivalent substitutions and modifications made within the spirit or scope defined by this claim. The same component number may be used to represent the same or similar parts in all drawings.

[0057] The contents not described in detail in the present invention are well known to those skilled in the art.

Claims

1. A MEMS inertial measurement device that can withstand large overloads, It is characterized in that The invention comprises a base (1) and a support assembly, a vibration-damping pad (2) and a supporting screw (3) located on the base (1); the support assembly comprises a support (4), a processing board (5), a chip and a potting glue layer (6); the processing board (5) is fixed on the support (4) and connected to a plurality of the chips; the potting glue layer (6) is filled in the gap between the support (4) and the plurality of the chips so that each of the chips is suspended and mounted on the base (1); the supporting screw (3) is sequentially inserted through the support (4) and the vibration-damping pad (2) and connected to the base (1); the vibration-damping pad (2) is arranged at the contact position between the base (1) and the support (4); The plurality of chips include an accelerometer chip (7) and a gyroscope chip (8), wherein the accelerometer chip (7) and the gyroscope chip (8) are respectively fixed on corresponding circuit boards (9), and the circuit boards (9) are connected to the processing board (5); The circuit board (9) is connected to the processing board (5) in a suspended manner; The vibration-damping pad (2) comprises a first vibration-damping portion (201), a connecting portion (202) and a second vibration-damping portion (203) which are connected in sequence, the first vibration-damping portion (201) and the second vibration-damping portion (203) being symmetrically arranged at two ends of the connecting portion (202), and the horizontal plane where the center of gravity of the bracket assembly is located overlaps with the horizontal plane where the center of gravity of the vibration-damping pad (2) is located; The four corner portions (401) are respectively located at the four corners of the bracket (4); the corner portions (401) are boss-shaped; the first vibration-damping portion (201) and the second vibration-damping portion (203) are respectively located on the upper and lower end surfaces of the corner portions (401); The intersection of the line connecting the two spaced corner portions (401) and the line connecting the center of gravity of the support assembly are perpendicular to the base (1).

2. The MEMS inertial measurement device capable of withstanding large overload according to claim 1, It is characterized in that The support (4) is in the shape of a hollow polygonal prism, the plurality of chips are located on the outside of the support (4), the processing board (5) is fixed to the top opening of the support (4), and at least one corner portion (401) of the support (4) is connected to the base (1) via the vibration-damping pad (2).

3. The MEMS inertial measurement device capable of withstanding large overload according to claim 1, It is characterized in that The supporting screw (3) is screwed to the base (1) and is used to adjust the elasticity of the vibration-damping pad (2).

4. The MEMS inertial measurement device capable of withstanding large overload according to any one of claims 1 to 3, It is characterized in that The vibration-damping pad (2) is made of superelastic rubber material.

5. The MEMS inertial measurement device capable of withstanding large overload according to any one of claims 1 to 3, It is characterized in that The potting glue layer (6) is made of silicone rubber.

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