CN203376085U - High precision double-end fixing resonant tuning fork type pressure sensor - Google Patents

Abstract

The utility model discloses a high-precision double-end fixed resonant tuning fork type pressure sensor, which comprises a pressure bearing unit, a micro-lever mechanism, a flexible contact point, a pressure tuning fork, a reference tuning fork, an excitation piezoelectric element, a frequency measuring piezoelectric element, and a main body and the embedded processing module, the pressure tuning fork and the reference tuning fork are located on the same constant elastic alloy substrate body, have the same size and are adjacent to each other, the tuning fork arms of the two tuning forks are parallel to each other, and each has an excitation piezoelectric element and a The frequency-measuring piezoelectric element is installed on the two tuning fork arms of each tuning fork. The input of the excitation piezoelectric element and the output of the frequency-measuring piezoelectric element are connected to the embedded processing module. Both ends of the reference tuning fork are fixed on the main body, and one end of the pressure tuning fork is fixed. On the main body, the other end is connected with the micro-lever mechanism, one end of the micro-lever mechanism is connected with the constant elastic alloy substrate through a flexible contact point, and the other end of the micro-lever mechanism is connected with the pressure bearing unit. The above-mentioned pressure sensor adopts the combination of two resonant tuning forks, which has a simple structure and is convenient to implement temperature drift compensation, which improves the long-term use accuracy of the pressure sensor.

Description

A high-precision double-ended fixed resonant tuning fork pressure sensor

technical field

The utility model relates to a high-precision pressure measurement sensor, in particular to a double-end fixed resonant tuning fork type pressure sensor which improves measurement accuracy by solving the problem of temperature drift. the

Background technique

The pressure sensor is the most widely used sensor. It is a measuring element that uses various mechanisms and measurement principles to convert pressure into measurable voltage, current analog signals or frequency digital signals. Double-ended fixed resonant tuning fork pressure sensor is a high-precision frequency output pressure sensor. Double-ended fixed resonant tuning fork (DETF) is a new type of resonant structure. It is processed by wire cutting, photolithography, corrosion and other methods on a material with low temperature drift characteristics. It is composed of two parallel beams. Beam The ends of it are merged and connected with other structures, shaped like a tuning fork whose two ends are merged and fixed. When the two tuning fork arms vibrate in anti-phase in their plane through a suitable excitation method, the stress and moment generated by the two tuning fork arms in their merged area are in opposite directions and cancel each other out, so that the entire structure is connected to the outside world through the fixed connection end. The energy coupling is negligible, and the energy loss of the vibration system is small. When there is an external axial force, the natural vibration frequency of the tuning fork arm changes in a linear relationship with it. According to this principle, connecting the double-ended fixed resonant tuning fork to other structures can be made into a pressure with frequency signal as the output. The pressure sensor has the characteristics of simple structure, good linearity, high sensitivity, easy mass production, and easy interface with computer, etc. It has been widely used in precision digital balances. the

In actual work, due to the influence of temperature on the material, the natural frequency of the double-ended fixed resonant tuning fork will change, thereby affecting the accuracy of the measurement. In order to correct the temperature measurement drift, in addition to using low-temperature drift coefficient materials, the general method is to install a temperature-sensitive element next to the sensor, and measure the drift data at different temperatures, and perform temperature drift compensation through software correction, so that Improve the stability of measurements at different temperatures. Due to the temperature measurement software compensation method, there are differences in the material and size of the tuning fork and the influence of processing accuracy, which makes the temperature drift of each tuning fork different, so it is necessary to use multi-point temperature measurement compensation one by one, which is time-consuming and laborious; at the same time Because of the aging problem of the material after use, its temperature drift characteristics will change, which will affect the long-term stability of the measurement. the

Contents of the invention

In order to overcome the deficiencies of the prior art, the purpose of the utility model is to provide a high-precision double-ended fixed resonant tuning fork pressure sensor. the

In order to achieve the above object, the technical solution of the utility model is: it includes a pressure bearing unit, a micro-lever mechanism, a flexible contact point, a pressure tuning fork, a reference tuning fork, an exciting piezoelectric element, a frequency measuring piezoelectric element, a main body and an embedded processing module , the pressure tuning fork and the reference tuning fork are located on the same main body base material, have the same size and are located adjacent to each other. The tuning fork arms of the two tuning forks are parallel to each other, and each has an excitation piezoelectric element and a frequency measurement piezoelectric element installed On the two tuning fork arms of the tuning fork, both the excitation piezoelectric element input and the frequency measurement piezoelectric element output are connected to the embedded processing module. the

The double-end fixed resonant tuning fork pressure sensor adopts the above structure. The pressure tuning fork is connected with the external pressure through the micro-lever mechanism and the pressure bearing unit, and is used to output the frequency signal corresponding to the external pressure. The reference tuning fork is fixed at both ends, and is not connected with Any external pressure is directly connected to output a fixed frequency signal. Since the two tuning forks are adjacent to each other and made of the same material, when the external temperature changes, the two tuning forks will be affected by the same temperature drift. At this time, the frequency change of the reference tuning fork that is not connected to the external pressure can be measured Used as temperature drift compensation for pressure tuning forks. the

After adopting the above structure, the beneficial effect of the utility model is: the temperature drift compensation is simple and easy to use, the system only needs to save the initial frequency of the two tuning forks and a linear factor when leaving the factory, and the temperature drift compensation of the pressure tuning fork can be achieved through simultaneous It is realized by measuring the variation of the frequency of the reference tuning fork, so that it does not need time-consuming and laborious point-by-point temperature pre-measurement and multi-point data storage compensation, and avoids inaccurate compensation caused by temperature drift data changes due to performance aging when the equipment is running for a long time. question. The sensor has a simple structure, less manual intervention, reduces labor intensity, improves work efficiency, and improves the long-term use precision of the pressure sensor. the

Description of drawings

Below in conjunction with accompanying drawing, the utility model is described in further detail:

Fig. 1 is the front view of the utility model;

Detailed ways

In order to have a further understanding and understanding of the structural features of the present utility model and the functional effects it achieves, a detailed description is provided in conjunction with preferred embodiments and accompanying drawings, as follows:

As shown in Figure 1, the utility model includes a pressure bearing unit 1, a micro-lever mechanism 2, a flexible contact point 3, a pressure tuning fork 4, a reference tuning fork 5, an excitation piezoelectric element 6, a frequency measuring piezoelectric element 7, a main body 8 and Embedded processing module 9, the pressure tuning fork 4 and the reference tuning fork 5 are located on the same main body 8 base material, have the same size and adjacent positions, the tuning fork arms of the two tuning forks are parallel to each other, and each has an excitation piezoelectric element 6 and A frequency-measuring piezoelectric element 7 is installed on the two tuning fork arms of each tuning fork, and the input 6 of the exciting piezoelectric element and the output of the frequency-measuring piezoelectric element 7 are both connected to the embedded processing module 9 . the

The material of the main body 8 is a constant elastic alloy. the

The pressure bearing unit 1, the micro-lever mechanism 2, the flexible contact point 3, the pressure tuning fork 4, and the reference tuning fork 5 are all formed on a whole piece of constant elastic alloy substrate through wire cutting, photolithography, and corrosion processing, and each part is connected. It is a complete organic whole. the

Both ends of the reference tuning fork 5 are fixed on the main body 8 . the

One end of the pressure tuning fork 4 is fixed on the main body 8 , and the other end is connected with the micro-lever mechanism 2 . the

One end of the micro-lever mechanism 2 is connected to the main body 8 through a flexible contact point 3, and the flexible contact point 3 is used as a lever fulcrum, and the other end of the micro-lever mechanism 2 is connected to the pressure bearing unit 1 above. the

The implementation process of the utility model is as follows:

In actual use (temperature is T), when the sensor pressure bearing unit 1 is subjected to pressure, the output value X0(T) of the pressure tuning fork 4 can be measured due to the change of the axial force, and the output value of the reference tuning fork 5 can be detected at the same time X1(T). X0(T) and X1(T) can be measured simultaneously. the

The system saves the initial resonance value X0 (T0) of the pressure tuning fork 4 and the initial resonance value X1 (T0) of the reference tuning fork 5 when it leaves the factory (temperature is T0). the

When compensating for temperature drift, the frequency output variation of the reference tuning fork 5 is obtained by calculation Δ1(T) = X1(T)-X1(T0), and this variation is used as the compensation reference value of the pressure tuning fork 4, that is, the pressure after actual compensation The frequency output value of the tuning fork 4 is adjusted to X0(T)'=X0(T)-KΔ1(T), where K is a linear factor set according to the difference in the size of the two tuning forks, which can be set in factory calibration. The frequency change value of the final pressure tuning fork 4 is Δ(T)=X0(T)'-X0(T0). the

A high-precision double-ended fixed resonant tuning fork pressure sensor provided by this technical solution has been introduced in detail above. For those of ordinary skill in the art, based on the idea of implementing this technical solution, they will understand both the specific implementation and the scope of application. There are changes. In summary, the content of this specification should not be understood as a limitation on this technical solution. Any changes made according to the design idea of this technical solution are within the protection scope of this utility model patent. the

Claims (6)

1. A high-precision double-ended fixed resonance tuning fork type pressure sensor is characterized in that: it includes a pressure bearing unit, a micro-lever mechanism, a flexible contact point, a pressure tuning fork, a reference tuning fork, an exciting piezoelectric element, a frequency measuring piezoelectric element, The main body and the embedded processing module, the pressure tuning fork and the reference tuning fork are located on the same main body substrate, have the same size and are adjacent to each other, the tuning fork arms of the two tuning forks are parallel to each other, and each has an excitation piezoelectric element and a frequency measurement The piezoelectric element is installed on the two tuning fork arms of each tuning fork, and both the input of the excitation piezoelectric element and the output of the frequency measurement piezoelectric element are connected to the embedded processing module. 2. A high-precision double-ended fixed resonant tuning fork pressure sensor according to claim 1, characterized in that: the material of the main body is a constant elastic alloy. 3. A high-precision double-ended fixed resonant tuning fork pressure sensor according to claim 1, characterized in that: the pressure bearing unit, the micro-lever mechanism, the flexible contact point, the pressure tuning fork, and the reference tuning fork are all in one piece The constant elastic alloy substrate is formed by wire cutting, photolithography and corrosion processing, and all parts are connected to form a complete organic whole. 4. A high-precision double-ended fixed resonant tuning fork pressure sensor according to claim 1, wherein both ends of the reference tuning fork are fixed on the main body. 5. A high-precision double-ended fixed resonant tuning fork pressure sensor according to claim 1, characterized in that one end of the pressure tuning fork is fixed on the main body, and the other end is connected with a micro-lever mechanism. 6. A high-precision double-ended fixed resonant tuning fork pressure sensor according to claim 1, characterized in that: one end of the micro-lever mechanism is connected to the main body through a flexible contact point, and the flexible contact point is used as a lever fulcrum, The top of the other end of the micro-lever mechanism is connected with the pressure bearing unit.

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