A pendulum-type all-quartz resonant accelerometer with dual flexible support and its assembly method

Abstract

A pendulum-type all-quartz resonant accelerometer with dual flexible support and its assembly method are disclosed. The accelerometer includes a sensitive mass block structure composed of a mass block, flexible supports for the mass block, and a stress isolation zone. An upper resonant beam is connected above the mass block, and a lower resonant beam is connected below the mass block. A lower limit plate is connected below the sensitive mass block structure and is connected to a mounting base. An upper limit plate is connected above the sensitive mass block structure. The lower limit plate, the sensitive mass block structure, and the upper limit plate pass through positioning terminals. A housing is provided on the outer side of the lower limit plate, the sensitive mass block structure, and the upper limit plate, and the housing is connected to the mounting base. The upper and lower resonant beams are electrically connected to a resonant circuit within the mounting base via positioning terminals, transmitting signals to the resonant circuit. This invention improves the environmental adaptability of the accelerometer, reduces its temperature characteristics, and decreases its size, adapting to the miniaturization and high-precision development trend of inertial navigation systems.

Description

Technical Field

[0001] This invention relates to the field of accelerometer technology, specifically to a pendulum-type all-quartz resonant accelerometer with dual flexible support and its assembly method. Background Technology

[0002] Inertial navigation is the foundation of precision strikes, and accelerometers are one of the core instruments in inertial navigation. Their accuracy determines the strike capability of weapons and equipment. With technological advancements, weapon models place increasingly higher demands on the size, accuracy, and reliability of accelerometers, and existing accelerometers fall short of future equipment requirements. Quartz resonant accelerometers, with their small size, high precision potential, digital output, and strong environmental adaptability, are considered by the industry to be the representative product of the next generation of high-precision accelerometers. Because quartz resonant accelerometers provide direct digital output, they effectively reduce the accuracy errors caused by analog-to-digital conversion, while saving space on analog-to-digital conversion boards for inertial navigation systems. This aligns with the miniaturization trend of inertial navigation systems, making quartz resonant accelerometers a hot research topic in research institutions worldwide.

[0003] The existing quartz resonant accelerometer (Zhang Liyuan, Quartz Vibrating Beam Accelerometer System Based on Double Beam Structure [D], Southeast University, 2016) has the structural principle of a resonant beam attached to a mass block supported by a single flexible hinge. The resonant beam and the mass block are assembled by welding. The welding of the resonant beam and the mass block generates large assembly stress, which affects the bias stability of the accelerometer. The mass block is designed with a single flexible support, which has poor resistance to mechanical forces under large mechanical environments. The resonant beam and the mass block are made of dissimilar materials with different coefficients of linear expansion, resulting in certain discrepancies between the temperature characteristics of the accelerometer and the actual application model.

[0004] As the core instrument of the inertial navigation acceleration channel, the quartz resonant accelerometer theoretically achieves an accuracy of 1.0E-07. With improvements in quartz material performance and MEMS technology, the accuracy and reliability of the quartz resonant accelerometer will reach a high level, and it will have broad application prospects in aviation, aerospace, navigation, and weaponry. However, the existing technology still has the following drawbacks: 1) The environmental adaptability of the existing quartz resonant accelerometer is still somewhat different from that of practical applications and needs further improvement; 2) The temperature characteristics (including temperature coefficient and temperature hysteresis) of the existing quartz resonant accelerometer are relatively high, which is a key factor limiting its application; 3) The size of the existing quartz resonant accelerometer is still relatively large, which is not suitable for the miniaturization and high-precision development trend of inertial navigation systems. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a pendulum-type all-quartz resonant accelerometer with dual flexible support and its assembly method, which improves the environmental adaptability of the accelerometer, reduces the temperature characteristics of the accelerometer, reduces the volume of the accelerometer, and adapts to the miniaturization and high precision development trend of inertial navigation systems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A pendulum-type all-quartz resonant accelerometer with dual flexible support includes a sensitive mass block structure consisting of a mass block 3, a mass block flexible support 4, and a stress isolation zone 5. An upper resonant beam 6 is connected above the mass block 3, and a lower resonant beam 7 is connected below the mass block 3.

[0008] A lower limit plate 2 is connected below the sensitive mass block structure, and the lower limit plate 2 is connected to the mounting base 1 below; an upper limit plate 8 is connected above the sensitive mass block structure, and the lower limit plate 2, the sensitive mass block structure, and the upper limit plate 8 pass through the positioning terminal 9; a housing 10 is provided on the outside of the lower limit plate 2, the sensitive mass block structure, and the upper limit plate 8, and the housing 10 is connected to the mounting base 1.

[0009] The upper resonant beam 6 and the lower resonant beam 7 are electrically connected to the resonant circuit in the mounting base 1 via the positioning terminal 9, and the signal is transmitted to the resonant circuit.

[0010] The sensitive mass block structure is made of far-ultraviolet quartz glass and includes a mass block 3. The mass block 3 is sensitive to external input acceleration and provides an installation frame for the upper resonant beam 6 and the lower resonant beam 7. The upper resonant beam installation groove 16 is provided above the fixed end of the mass block 3, and the lower resonant beam installation groove 17 is provided below it. The lower resonant beam signal electrode lead-out layers 18 are symmetrically provided on the left and right sides above the fixed end of the mass block 3. The two sides of the fixed end of the mass block 3 are connected to the mass block flexible support 4. The mass block flexible support 4 is connected to the mass block swing tongue 21. The mass block swing tongue 21 and the mass block flexible support 4 are provided with a stress isolation zone 5. The outer mounting frame 22 around the mass block 3 is provided with multiple mounting bosses 20 on the upper and lower sides for mounting the upper limit plate 8 and the lower limit plate 2, respectively. The outer side of the upper resonant beam 6 and the lower resonant beam 7 is provided with a resonant beam vibration limit plate 19.

[0011] The mounting base 1 is made of stainless steel, the resonant circuit is embedded in the mounting base 1, and multiple positioning terminals 9 are sintered on the mounting base 1.

[0012] The upper limit plate 8 and the lower limit plate 2 have the same structure and are made of far-ultraviolet quartz glass. The left and right sides of the interior each have sintered holes 14 for positioning terminals, and the outer side has multiple boss mounting holes 15.

[0013] The upper resonant beam 6 and lower resonant beam 7 are based on the piezoelectric effect. When an external accelerometer is input, the mass block 3 converts the external input accelerometer into an applied force. The upper resonant beam 6 and lower resonant beam 7 are sensitive to the change in applied force and convert the change in force into a change in frequency. One frequency of the upper resonant beam 6 increases and the other frequency of the lower resonant beam 7 decreases. The frequency difference between the two resonant beams is linearly related to the input acceleration, thus realizing acceleration measurement.

[0014] The outer casing 10 is connected to the mounting base 1 by a sealant or laser welding to achieve the sealing of the accelerometer.

[0015] The positioning terminal 9 achieves precise positioning of the upper limit plate 8 and the lower limit plate 2 and signal output of the upper resonant beam 6 and the lower resonant beam 7 through the positioning terminal through hole 14 of the upper limit plate 8 and the lower limit plate 2. The material is stainless steel with silver plating on the outer surface.

[0016] An assembly method for a pendulum-type all-quartz resonant accelerometer with dual flexible support includes the following steps:

[0017] 1) The mounting base 1 is placed on the positioning fixture, and multiple positioning terminals 9 pass through the resonant circuit and are sintered on the mounting base 1;

[0018] 2) The lower limit plate 2 is positioned by the positioning terminal 9 and fixed to the mounting base 1 by adhesive bonding. The mounting boss 20 of the outer mounting frame 22 of the sensitive mass block structure is bonded to the boss mounting hole 15 of the lower limit plate 2 and the upper limit plate 8.

[0019] 3) Multiple positioning terminals 9 pass through the lower limit plate 2, the sensitive mass block structure, and the upper limit plate 8. The output signals of the upper resonant beam 6 and the lower resonant beam 7 are connected to the positioning terminals 9 on the left and right halves to achieve positioning and signal output. The outer shell 10 and the mounting base 1 are bonded together with sealant to achieve the sealing of the accelerometer.

[0020] Compared with existing technologies, this invention has the following advantages: This invention combines the design principles of a quartz flexible accelerometer pendulum and a resonant accelerometer structure, employing a dual-mass flexible support and a resonant accelerometer mass-sense structure with a stress isolation zone. It inherits the strong environmental adaptability of flexible accelerometers and uses a resonant beam to sense and output frequency signals, thus realizing the digitization of the accelerometer output. It has the following advantages:

[0021] (1) The present invention adopts the design of mounting bosses on the upper and lower parts of the outer mounting frame. The mounting bosses are closely matched with the lower limit plate and the upper limit plate, which improves the stability and sealing of the watch core structure.

[0022] (2) The lower limit plate, upper limit plate and sensitive mass block structure of this invention are all made of far-ultraviolet quartz glass with a linear expansion coefficient of 0.5ppm. The use of homogeneous materials reduces the overall temperature coefficient and long-term repeatability, which is more conducive to model application. It avoids the problem of poor temperature characteristics caused by different linear expansion coefficients of heterogeneous materials, greatly reduces the temperature coefficient and temperature hysteresis of the product, and improves temperature adaptability.

[0023] (3) The outer casing of this invention is connected to the mounting base by a sealing adhesive or laser welding, achieving a two-stage seal between the watch movement and the entire watch, with a sealing performance of 1.0E-10 Pa·m. 3 / s ensures the long-term repeatability of the accelerometer's bias.

[0024] (4) Since the present invention uses a dual mass block to flexibly support the mass block, the stability of the mass block is improved, which greatly improves the mechanical environment adaptability of the resonant accelerometer and lays the foundation for model application.

[0025] (5) The sensitive mass block structure of the present invention has a stress isolation zone, which reduces the stress interference of the mass block on the resonant beam and improves the stability of the product.

[0026] (6) The present invention has a simple structure and its external dimensions can reach Smaller size, meeting the development trend of low cost and miniaturization.

[0027] (7) The structure and assembly of the present invention are easy to realize, and can give full play to the advantages of the pendulum-type all-quartz resonant accelerometer with double flexible support. Attached Figure Description

[0028] Figure 1 This is a cross-sectional view of the accelerometer in an embodiment of the present invention.

[0029] Figure 2 This is a top view of the mounting base of the accelerometer according to an embodiment of the present invention.

[0030] Figure 3 These are top and cross-sectional views of the upper and lower limit plates of the accelerometer in an embodiment of the present invention.

[0031] Figure 4 This is a top view of the mass block of the accelerometer in an embodiment of the present invention.

[0032] Figure 5 This is a cross-sectional view of the mass block of the accelerometer in an embodiment of the present invention.

[0033] Figure 6 This is a top view of the resonant beam of the accelerometer according to an embodiment of the present invention.

[0034] In the diagram: 1-Mounting base, 2-Lower limit plate, 3-Mass block, 4-Mass block flexible support, 5-Stress isolation zone, 6-Upper resonant beam, 7-Lower resonant beam, 8-Upper limit plate, 9-Positioning terminal block, 10-Outer shell, 11-Accelerometer mounting hole, 12-Positioning terminal block mounting hole, 13-Accelerometer signal output hole, 14-Positioning terminal block sintering hole, 15-Boss mounting hole, 16-Upper resonant beam mounting groove, 17-Lower resonant beam mounting groove, 18-Lower resonant beam signal electrode lead-out layer, 19-Resonant beam vibration limit plate, 20-Mounting boss, 21-Mass block swing tongue, 22-Outer mounting frame. Detailed Implementation

[0035] The present invention will be described in detail below with reference to the embodiments and accompanying drawings. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the embodiments fall within the protection scope of the present invention.

[0036] like Figures 1-6 As shown, a pendulum-type all-quartz resonant accelerometer with double flexible support includes a sensitive mass block structure composed of a mass block 3, a mass block flexible support 4, and a stress isolation zone 5. An upper resonant beam 6 is connected above the mass block 3, and a lower resonant beam 7 is connected below the mass block 3.

[0037] A lower limit plate 2 is connected below the sensitive mass block structure, and the lower limit plate 2 is connected to the mounting base 1 below; an upper limit plate 8 is connected above the sensitive mass block structure, and the lower limit plate 2, the sensitive mass block structure, and the upper limit plate 8 pass through the positioning terminal 9; a housing 10 is provided on the outside of the lower limit plate 2, the sensitive mass block structure, and the upper limit plate 8, and the housing 10 is connected to the mounting base 1.

[0038] The upper resonant beam 6 and the lower resonant beam 7 are electrically connected to the resonant circuit in the mounting base 1 via the positioning terminal 9, and the signal is transmitted to the resonant circuit.

[0039] The mounting base 1 is made of stainless steel. The resonant circuit is embedded in the mounting base 1, and four positioning terminals 9 are sintered onto the mounting base 1 to provide a mounting positioning reference for the accelerometer. Figure 2 As shown, the mounting base 1 has 4 accelerometer mounting holes 11, 4 positioning terminal mounting holes 12, and 6 accelerometer signal output holes 13.

[0040] The upper limit plate 8 and lower limit plate 2 provide an installation frame for the sensitive mass block structure and limit the displacement of the mass block's swing tongue during operation, thus providing protection; for example Figure 3 As shown, the upper limit plate 8 and the lower limit plate 2 have the same structure and are made of far-ultraviolet quartz glass. There are two positioning terminal sintering holes 14 on the left and right sides of the interior, and three boss mounting holes 15 on the outside.

[0041] like Figure 4 , Figure 5 As shown, the sensitive mass block structure is the core sensitive structure, made of far-ultraviolet quartz glass, and includes a mass block 3. The mass block 3 senses external input acceleration and provides a mounting frame for the upper resonant beam 6 and the lower resonant beam 7. An upper resonant beam mounting groove 16 is provided above the fixed end of the mass block 3, and a lower resonant beam mounting groove 17 is provided below it. The lower resonant beam signal electrode lead-out layers 18 are symmetrically arranged on the left and right sides above the fixed end of the mass block 3. Flexible supports 4 are connected to both sides of the fixed end of the mass block 3. The flexible supports 4 and the mass block swing tongue 2 are connected to the mass block. 1. The function of the flexible support 4 of the mass block is to support the swing tongue 21 of the mass block; a stress isolation zone 5 is provided between the swing tongue 21 of the mass block and the flexible support 4 of the mass block. The function of the stress isolation zone 5 is to reduce stress interference and improve product stability; the outer mounting frame 22 of the mass block 3 is provided with three mounting bosses 20 on the upper and lower sides for mounting the upper limit plate 8 and the lower limit plate 2 respectively; the outer side of the upper resonant beam 6 and the lower resonant beam 7 is provided with a resonant beam vibration limiting plate 19 to limit the amplitude of the upper resonant beam 6 and the lower resonant beam 7 in the vibration working state.

[0042] The upper resonant beam 6 and the lower resonant beam 7 are as follows: Figure 6 As shown, based on the piezoelectric effect, when an external accelerometer is input, the mass block 3 converts the external input accelerometer into an applied force. The upper resonant beam 6 and the lower resonant beam 7 are sensitive to the change in applied force and convert the change in force into a change in frequency. The frequency of the upper resonant beam 6 increases and the frequency of the lower resonant beam 7 decreases. The frequency difference between the two resonant beams is linearly related to the input acceleration, thus realizing acceleration measurement.

[0043] The outer casing 10 is bonded to the mounting base 1 with adhesive to achieve a seal for the accelerometer.

[0044] The positioning terminal 9 achieves precise positioning of the upper limit plate 8 and the lower limit plate 2 and signal output of the upper resonant beam 6 and the lower resonant beam 7 through the positioning terminal through hole 14 of the upper limit plate 8 and the lower limit plate 2. The material is stainless steel with silver plating on the outer surface.

[0045] The working principle of the accelerometer of this invention is as follows:

[0046] The mass block oscillating tongue 21 acts as a sensing element, converting the input acceleration signal into a force signal and transmitting it to the upper resonant beam 6 and the lower resonant beam 7. The upper resonant beam 6 and the lower resonant beam 7 sense the force change transmitted by the mass block oscillating tongue 21. Based on the piezoelectric effect, the frequency changes, and the frequency change has a certain linear relationship with the acceleration change. The upper resonant beam 6 and the lower resonant beam 7 are connected to the positioning terminal 9 through gold wires, transmitting the signal to the resonant circuit. The resonant circuit detects the frequency change and then calculates the external input acceleration to realize the sensing measurement.

[0047] An assembly method for a pendulum-type all-quartz resonant accelerometer with dual flexible support includes the following steps:

[0048] 1) The mounting base 1 is placed on the positioning fixture as the installation reference for the entire accelerometer. The four positioning terminals 9 pass through the resonant circuit and are sintered on the mounting base 1 to provide the installation reference for the upper limit plate 8 and the lower limit plate 2.

[0049] 2) The lower limit plate 2 is positioned by the positioning terminal 9 and fixed to the mounting base 1 by adhesive bonding. The mounting boss 20 of the outer mounting frame 22 of the sensitive mass block structure is bonded to the boss mounting hole 15 of the lower limit plate 2 to achieve precise positioning and fit. The upper limit plate 8 is also etched with boss mounting holes 15. The mounting boss 20 of the outer mounting frame 22 of the sensitive mass block structure is bonded to the boss mounting hole 15 of the upper limit plate 8 to achieve precise positioning and fit.

[0050] 3) The four positioning terminals 9 pass through the lower limit plate 2, the sensitive mass block structure, and the upper limit plate 8. The output signals of the upper resonant beam 6 and the lower resonant beam 7 are respectively welded to the positioning terminals 9 on the left and right halves by gold wires to realize positioning and signal output. The outer shell 10 and the mounting base 1 are bonded together with sealant to realize the sealing of the accelerometer.

Claims

1. A pendulum-type all-quartz resonant accelerometer with dual flexible support, characterized in that: The structure includes a sensitive mass block structure consisting of a mass block (3), a mass block flexible support (4), and a stress isolation zone (5). An upper resonant beam (6) is connected above the mass block (3), and a lower resonant beam (7) is connected below the mass block (3). A lower limit plate (2) is connected to the lower part of the sensitive mass block structure, and the lower limit plate (2) is connected to the mounting base (1); an upper limit plate (8) is connected to the upper part of the sensitive mass block structure, and the lower limit plate (2), the sensitive mass block structure, and the upper limit plate (8) pass through the positioning terminal (9); a shell (10) is provided on the outside of the lower limit plate (2), the sensitive mass block structure, and the upper limit plate (8), and the shell (10) is connected to the mounting base (1); The upper resonant beam (6) and the lower resonant beam (7) are electrically connected to the resonant circuit in the mounting base (1) via the positioning terminal (9) to transmit the signal to the resonant circuit; The sensitive mass block structure material is far-ultraviolet quartz glass, including a mass block (3), with a mass block flexible support (4) connected to both sides of the fixed end of the mass block (3), the mass block flexible support (4) and the mass block swing tongue (21) connected, and a stress isolation zone (5) is provided between the mass block swing tongue (21) and the mass block flexible support (4). The mass block (3) is provided with an upper resonant beam mounting groove (16) above the fixed end and a lower resonant beam mounting groove (17) below. The lower resonant beam signal electrode lead-out layers (18) are symmetrically provided on the left and right sides above the fixed end of the mass block (3). The upper resonant beam (6) and the lower resonant beam (7) are provided with resonant beam vibration limiting plates (19) on the outside. The outer mounting frame (22) surrounding the mass block (3) is provided with multiple mounting bosses (20) on the upper and lower sides for mounting the upper limit plate (8) and the lower limit plate (2).

2. The pendulum-type all-quartz resonant accelerometer with dual flexible support according to claim 1, characterized in that: The mounting base (1) is made of stainless steel, the resonant circuit is embedded in the mounting base (1), and multiple positioning terminals (9) are sintered on the mounting base (1).

3. The pendulum-type all-quartz resonant accelerometer with dual flexible support according to claim 1, characterized in that: The upper limit plate (8) and the lower limit plate (2) have the same structure and are made of far-ultraviolet quartz glass. The left and right sides of the interior each have sintered holes (14) for positioning terminals, and the outer side has multiple boss mounting holes (15).

4. The pendulum-type all-quartz resonant accelerometer with dual flexible support according to claim 1, characterized in that: The upper resonant beam (6) and lower resonant beam (7) are based on the piezoelectric effect. When an external accelerometer is input, the mass block (3) converts the external input accelerometer into an applied force. The upper resonant beam (6) and lower resonant beam (7) are sensitive to the change in applied force and convert the change in force into a change in frequency. The frequency of the upper resonant beam (6) increases and the frequency of the lower resonant beam (7) decreases. The frequency difference between the two resonant beams is linearly related to the input acceleration, thus realizing acceleration measurement.

5. A pendulum-type all-quartz resonant accelerometer with dual flexible support according to claim 1, characterized in that: The outer shell (10) is connected to the mounting base (1) by a sealant or laser welding to achieve the sealing of the accelerometer.

6. The pendulum-type all-quartz resonant accelerometer with dual flexible support according to claim 1, characterized in that: The positioning terminal (9) achieves precise positioning of the upper limit plate (8) and lower limit plate (2) and signal output of the upper resonant beam (6) and lower resonant beam (7) through the positioning terminal through hole (14) of the upper limit plate (8) and lower limit plate (2). The material is stainless steel with silver plating on the outer surface.

7. The assembly method of a pendulum-type all-quartz resonant accelerometer with dual flexible support according to any one of claims 1-6, characterized in that, Includes the following steps: 1) The mounting base (1) is placed on the positioning fixture, and multiple positioning terminals (9) pass through the resonant circuit and are sintered on the mounting base (1); 2) The lower limit plate (2) is positioned by the positioning terminal (9) and fixed to the mounting base (1) by adhesive bonding. The mounting boss (20) of the outer mounting frame (22) of the sensitive mass block structure is bonded to the mounting holes (15) of the lower limit plate (2) and the upper limit plate (8). 3) Multiple positioning terminals (9) pass through the lower limit plate (2), the sensitive mass block structure, and the upper limit plate (8). The output signals of the upper resonant beam (6) and the lower resonant beam (7) are connected to the positioning terminals (9) on the left and right halves to achieve positioning and signal output. The outer shell (10) and the mounting base (1) are bonded together with sealant to achieve the sealing of the accelerometer.

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