Quartz vibrating beam accelerometer with enhanced temperature environment adaptability

Abstract

According to the quartz vibrating beam accelerometer with enhanced temperature environment adaptability provided by the invention, a TO package of a sensitive structure is not fixedly mounted on an accelerometer shell in a conventional metal connection mode, but is fixed on the inner wall of the shell through an annular colloid, so that the influence of external environment temperature change can be reduced, and the temperature performance of the accelerometer is improved; the thermal baffle plate is arranged between the circuit and the sensitive structure meter head, so that the temperature gradient between the double beams of the sensitive structure caused by circuit starting temperature rise can be effectively reduced, and the starting time of the accelerometer is shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of MEMS inertial instruments or inertial devices, and relates to a quartz vibration beam accelerometer with enhanced temperature environment adaptability and good temperature performance. Background Art

[0002] The quartz vibration beam accelerometer is based on the piezoelectric principle for resonant excitation and charge detection. It has the advantages of high detection sensitivity, excellent material mechanical and temperature characteristics, simple structure and measurement and control circuit, and good long-term stability. It is one of the important development directions of high-precision and small-volume accelerometers and has been widely used in the fields of industry, aviation, aerospace, weapons, etc. at home and abroad. In foreign countries, the accelerometers for IMU combination such as SDI500 and TAC-440 of EMCORE in the United States and the integrated vibration beam accelerometers of Ixblue A5 series in France are representative. The accuracy has reached the navigation level, and the typical values ​​of full-temperature bias and scale factor stability are better than 20μg and 20ppm respectively. In China, quartz vibration beam accelerometers have also made great progress thanks to years of research accumulation in quartz materials, micro-addition processes and excitation circuits. The room temperature performance of the accelerometer is close to the foreign level, but the full temperature characteristics, especially in different temperature environments, or when the ambient temperature changes rapidly and randomly, still have a certain gap with foreign countries. The typical values ​​of full temperature bias and scale factor stability are at the level of 100μg and 100ppm respectively. At the same time, the sensitive structure of the quartz vibrating beam accelerometer generally adopts a dual-beam upper and lower differential design. The heat generated during the circuit startup process often produces a temperature gradient between the dual beams, resulting in a longer output stabilization time, that is, a longer startup process. Therefore, the temperature environment adaptability and startup time of the quartz vibrating beam accelerometer need to be improved in a targeted manner.

[0003] In order to improve the temperature environment adaptability of the quartz beam accelerometer, the following problems need to be improved or solved:

[0004] (1) Poor adaptability to temperature environment.

[0005] When the temperature of the working environment changes rapidly or irregularly, on the one hand, the total temperature change transmitted to the sensitive structure of the accelerometer is large, resulting in a large change in the frequency output of the resonant beam; on the other hand, the temperature gradient problem caused by the temperature change makes the effect of the dual resonant beam differential worse, and the effect of the conventional gradient compensation algorithm also deteriorates, resulting in a significant decrease in the temperature performance of the accelerometer.

[0006] (2) The startup time is long.

[0007] Generally, the sensitive structure is encapsulated in a metal shell to form a meter head, which is directly fixed to the metal shell of the accelerometer by laser welding. During the startup of the accelerometer, the circuit generates heat through conduction, radiation, etc., causing the temperature of the dual-resonance beam to change. Due to the different spatial positions, the frequency of the dual-resonance beam changes with temperature, which makes the stabilization time of the frequency differential output, that is, the startup time, often long, mostly in the range of 50s to 200s, which does not meet the application requirements of some fields. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0009] To this end, the present invention provides a quartz vibrating beam accelerometer with enhanced temperature environment adaptability. The present invention can not only reduce the impact of rapid or irregular changes in ambient temperature on the sensitive structure of the meter head, improve the temperature environment adaptability, and improve the temperature performance index of the accelerometer. At the same time, it can also shorten the startup time of the accelerometer by reducing the impact of the circuit startup temperature rise on the sensitive structure of the meter head.

[0010] The technical solution of the present invention is as follows:

[0011] The present invention provides a quartz vibration beam accelerometer with enhanced temperature environment adaptability, the accelerometer comprising: an accelerometer internal component, a mounting flange, a whole meter sealing bottom plate and an accelerometer housing, wherein the accelerometer internal component is arranged in the accelerometer housing, and comprises a sensitive structure, a stress isolation sheet, a meter head TO, a meter head TO cap, an annular colloid, a circuit TO, a heat insulation baffle and a rigid-flexible PCB circuit board;

[0012] The sensitive structure is fixed in the inner cavity of the meter head TO through a stress isolation sheet, and after the inside of the meter head TO is filled with nitrogen or argon, the meter head TO cap is used for laser seam welding to achieve airtight packaging of the sensitive structure in the meter head TO; the meter head TO is fixed to the inner wall of the accelerometer housing through a circle of annular colloid in the outer diameter, and the insulator pin array on the upper side of the meter head TO passes through the graphic vias of the heat insulation baffle and is connected to the lower side circuit board of the rigid-flexible PCB circuit board to achieve electrical connection between the sensitive structure and the rigid-flexible PCB circuit board; the heat insulation baffle is fixed to the accelerometer housing by bonding and is located between the rigid-flexible PCB circuit board and the meter head TO; the upper side circuit board of the rigid-flexible PCB circuit board is fixed to the circuit TO, and the insulator pin array on the circuit TO is used for electrical connection between the accelerometer and the external application system;

[0013] Among them, after the entire cavity of the accelerometer is evacuated to a preset vacuum degree or filled with argon gas at one atmosphere of pressure, the entire sealing bottom plate is welded to the accelerometer housing to achieve vacuum or airtight packaging of the entire accelerometer. The mounting flange is arranged on the accelerometer housing for fixed installation of the accelerometer, and the meter head TO and circuit TO are also distributed on both sides of the mounting flange.

[0014] Furthermore, the meter head TO is fixed to the inner wall of the accelerometer housing through a circle of annular colloid in the outer diameter, which is achieved in the following manner:

[0015] The sealed meter head TO is connected to the designed upper auxiliary positioning fixture and positioned through the blind hole on the meter head. The accelerometer housing is placed on the designed lower auxiliary positioning fixture and can be moved up and down, front and back, and left and right to achieve alignment with the meter head TO;

[0016] The outside of the meter head TO has an annular or special-shaped protrusion, which is used to form a slit with a set distance between it and the inner wall of the accelerometer housing. Glue is poured into the slit, and an annular colloid is formed after drying and curing. After the colloid is cured, the upper auxiliary positioning tool and the lower auxiliary positioning tool are removed, and the meter head TO is positioned and fixed to the accelerometer housing.

[0017] Furthermore, the set distance is 50um to 500um.

[0018] Furthermore, the circuit TO is fixed to the accelerometer housing by a laser welding ring.

[0019] Furthermore, the entire sealing bottom plate is welded to the accelerometer housing by means of a laser welding ring.

[0020] Furthermore, the sensitive structure is a split or integrated structure, and the sensitive structure can be a single beam or a double beam, and can also be a metal pendulum or a quartz pendulum.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] (1) Improve the temperature environment adaptability of the accelerometer and improve the full temperature performance:

[0023] The present invention uses heat-insulating colloid to fix the meter head, adds stress isolation sheets, performs secondary heat insulation between the meter head and the meter head TO, and performs heat optimization treatment between the meter head TO and the inner wall of the shell. On the one hand, the total heat transmitted to the sensitive structure by the ambient temperature change through conduction and radiation is reduced, and the frequency change of the single beam is reduced; on the other hand, the temperature gradient and gradient change rate between the dual resonance beams are reduced, and the differential and temperature compensation effects are improved. Finally, the adaptability to the temperature environment is improved, and the full-temperature performance of the accelerometer is improved.

[0024] (2) Reduce the accelerometer startup time:

[0025] The present invention arranges the meter head TO and the circuit TO on both sides of the mounting flange, increases the distance between the meter head and the circuit as much as possible, adds a heat insulation baffle, etc., so that the circuit startup temperature rise is transmitted to the mounting carrier through the mounting flange as much as possible, and the heat radiated and naturally convected to the meter head TO is reduced, thereby suppressing the influence of the startup temperature rise on the sensitive structure inside the meter head TO as much as possible, shortening the stabilization process of the dual-beam frequency differential output, and reducing the startup time of the accelerometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a quartz beam accelerometer solution with enhanced temperature environment adaptability;

[0028] Figure 2 The meter head TO is fixedly mounted to the housing through a ring-shaped colloid. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0032] like Figure 1 As shown, this embodiment provides a quartz vibration beam accelerometer with enhanced temperature environment adaptability. First, the sensitive structure 7 is fixed to the inner strength of the meter head TO 6 through the stress isolation sheet 5, and then after baking, degassing and other steps, after the inside of the meter head TO 6 is filled with nitrogen or argon, the meter head TO cap 8 is used for laser seam welding to achieve the airtight packaging of the sensitive structure 7 in the meter head TO 6; then, the meter head TO 6 is fixed to the accelerometer housing 12 through a circle of colloid 13 in the outer diameter. After the insulator pin array 3 on the upper side of the meter head TO 6 passes through the patterned vias of the heat insulation baffle 11, it is connected to the rigid-flexible PCB circuit 9 to achieve the electrical connection between the sensitive structure 7 and the circuit 9. The heat insulation baffle 11 is fixed to the accelerometer housing 12 through the colloid. The upper circuit board of the rigid-flexible PCB circuit 9 is fixed to the circuit TO 2, and the lower circuit board is connected to the insulator pin array 3 on the upper side of the meter head TO 6. The circuit TO 2 is fixed to the accelerometer housing 12 through the laser welding ring 10. Finally, after the accelerometer cavity is evacuated to a preset vacuum or filled with low thermal conductivity gas such as argon, the entire sealed bottom plate 15 is welded to the accelerometer housing 12 through a laser welding ring 14 to achieve vacuum or airtight packaging of the entire accelerometer. The insulator pin array 1 on the circuit TO 2 is used for electrical connection between the accelerometer and the external application system, and the mounting flange 4 is used for fixed installation of the accelerometer.

[0033] That is, after the sensitive structure 7 of this embodiment is mounted on the meter head TO 6, it is not directly mounted and fixed to the metal shell 12 of the accelerometer, but is fixed to the inner wall of the shell through the annular colloid 13 to reduce the influence of the external environmental temperature change and improve the temperature environment adaptability of the accelerometer. A heat insulation baffle 11 is installed between the circuit 9 and the meter head TO 6 to reduce the temperature gradient between the two beams of the sensitive structure caused by the temperature rise of the circuit startup and shorten the startup time of the accelerometer.

[0034] It can be seen that the sensitive structure 7 of this embodiment is installed on the meter head TO 6 through the stress insulation sheet 5, and after being airtightly packaged, it is fixed to the metal shell 12 through the insulation colloid 13. The meter head TO 6 and the circuit TO 2 are located on both sides of the accelerometer mounting flange, as far apart as possible, and a heat insulation baffle 11 is placed in the middle to block the heat radiation and natural convection of the circuit 9 to the meter head TO 6. The entire accelerometer is sealed in argon gas or low vacuum, similar to the principle of a thermos bottle, to reduce the impact of the external temperature environment on the thermal radiation of the internal meter head. The outer wall surface of the meter head TO 6 is mirror-finished, and the inside of the shell is blackened and sandblasted to further enhance the thermal radiation isolation effect.

[0035] Figure 2 The implementation method of accurately positioning the meter head TO 6 and fixing it to the shell 12 through the annular colloid 13 is given. The sealed meter head TO 6 is connected to the upper auxiliary positioning tool 17 and accurately positioned through the blind hole 18. The accelerometer shell 12 is placed on the lower auxiliary positioning tool 19 and can be finely moved up and down, front and back, left and right to achieve precise alignment with the meter head TO 6. The annular protrusion 16 on the outside of the meter head TO 6 is used to form a slit of 50um to 500um between the inner wall of the accelerometer shell 12. Glue is poured into the slit, and the annular colloid 13 is formed after drying and curing. After the colloid 13 is cured, the upper auxiliary positioning tool 17 and the lower auxiliary positioning tool 19 are removed, and the meter head TO 6 can be accurately positioned and fixed to the accelerometer shell 12.

[0036] Optionally, the sensitive structure of the quartz vibration beam accelerometer may be a split type or an integrated type structure, may be a single beam or a double beam, and may also be a metal pendulum or a quartz pendulum.

[0037] It can be seen that the embodiments of the present invention use methods such as using heat-insulating colloid to fix the meter head, adding stress isolation sheets, secondary heat insulation of the entire meter-meter head TO, and heat optimization treatment of the white head TO and the inner wall of the shell. On the one hand, by reducing the total heat of the ambient temperature change to the sensitive structure through conduction and radiation, the frequency change of the single beam is reduced; on the other hand, by reducing the temperature gradient and gradient change rate between the dual resonant beams, the differential and temperature compensation effects are improved. Ultimately, the temperature environment adaptability of the accelerometer is improved and the full temperature performance is improved. In addition, the embodiments of the present invention arrange the meter head TO and the circuit TO on both sides of the mounting flange, increase the distance between the meter head and the circuit as much as possible, and add a heat-insulating baffle. The circuit startup temperature rise is conducted to the mounting carrier through the mounting flange as much as possible, reducing the heat radiated and naturally convected to the meter head TO, thereby suppressing the influence of the startup temperature rise on the sensitive structure inside the meter head TO as much as possible, shortening the dual-beam frequency differential output stabilization process, and reducing the startup time of the accelerometer.

[0038] Features described and / or illustrated above for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or used in place of features in other embodiments.

[0039] It should be emphasized that the term "include / comprises" when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps, components or combinations thereof.

[0040] The many features and advantages of these embodiments are apparent from this detailed description, and thus the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not intended that the embodiments of the invention be limited to the exact construction and operation illustrated and described, but rather all suitable modifications and equivalents falling within the scope thereof are intended to be covered.

[0041] Parts of the present invention that are not described in detail are well known to those skilled in the art.

Claims

1. A quartz beam accelerometer with enhanced temperature environment adaptability, characterized in that: The accelerometer comprises: an accelerometer internal component, a mounting flange, a whole meter sealing bottom plate and an accelerometer housing, wherein the accelerometer internal component is arranged in the accelerometer housing, and comprises a sensitive structure, a stress isolation sheet, a meter head TO, a meter head TO cap, an annular colloid, a circuit TO, a heat insulation baffle and a rigid-flexible PCB circuit board; The sensitive structure is fixed in the inner cavity of the meter head TO through a stress isolation sheet, and after the inside of the meter head TO is filled with nitrogen or argon, the meter head TO cap is used for laser seam welding to achieve airtight packaging of the sensitive structure in the meter head TO; the meter head TO is fixed to the inner wall of the accelerometer housing through a circle of annular colloid in the outer diameter, and the insulator pin array on the upper side of the meter head TO passes through the graphic vias of the heat insulation baffle and is connected to the lower circuit board of the rigid-flexible PCB circuit board to achieve electrical connection between the sensitive structure and the rigid-flexible PCB circuit board; the heat insulation baffle is fixed to the accelerometer housing by bonding and is located between the rigid-flexible PCB circuit board and the meter head TO; the upper circuit board of the rigid-flexible PCB circuit board is fixed to the circuit TO, and the insulator pin array on the circuit TO is used for electrical connection between the accelerometer and the outside; Among them, after the entire cavity of the accelerometer is evacuated to a preset vacuum degree or filled with argon gas, the entire sealing bottom plate is welded to the accelerometer housing to achieve vacuum or airtight packaging of the entire accelerometer. The mounting flange is arranged on the accelerometer housing for fixed installation of the accelerometer, and the meter head TO and circuit TO are distributed on both sides of the mounting flange.

2. The quartz vibrating beam accelerometer with enhanced temperature environment adaptability according to claim 1, characterized in that: The meter head TO is fixed to the inner wall of the accelerometer housing through a ring of colloid in the outer diameter, which is achieved in the following way: The sealed meter head TO is connected to the designed upper auxiliary positioning fixture and positioned through the blind hole on the meter head. The accelerometer housing is placed on the designed lower auxiliary positioning fixture and can be moved up and down, front and back, and left and right to achieve alignment with the meter head TO; The outside of the meter head TO has a ring-shaped or special-shaped protrusion, which is used to form a slit with a set distance between it and the inner wall of the accelerometer housing. Glue is poured into the slit, and after drying and curing, a ring-shaped colloid is formed; After the colloid is solidified, the upper auxiliary positioning fixture and the lower auxiliary positioning fixture are removed, and the meter head TO is positioned and fixedly connected to the accelerometer housing.

3. The quartz vibrating beam accelerometer with enhanced temperature environment adaptability according to claim 2, characterized in that: The set distance is 50um to 500um.

4. A quartz vibrating beam accelerometer with enhanced temperature environment adaptability according to claim 1 or 2, characterized in that: The circuit TO is fixed to the accelerometer housing by laser welding.

5. A quartz vibrating beam accelerometer with enhanced temperature environment adaptability according to claim 1 or 4, characterized in that: The sealing base plate is welded to the accelerometer housing via a laser welding ring.

6. The quartz vibrating beam accelerometer with enhanced temperature environment adaptability according to claim 1, characterized in that: The sensitive structure is a split or integrated structure, and the sensitive structure can be a single beam or a double beam, and can also be a metal pendulum or a quartz pendulum.

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