CN1175685A - A High Stability Quartz Resonant Force Sensor - Google Patents

Abstract

The invention relates to a piezoelectric resonant force sensor, aiming at the defects of poor stability, large creep and short life in the prior art, the sensor adopts a double-diaphragm support structure and glue with a higher glass transition temperature as components to adhere to components. Therefore, the piezoelectric resonant force sensor has good stability, small creep and greatly improved service life.

Description

A High Stability Quartz Resonant Force Sensor

The invention relates to a force measuring device, especially a force sensor using a piezoelectric quartz resonator as a sensitive element.

As early as the 1960s and 1970s, scientists used the force-frequency characteristics of quartz resonators in the development of force, pressure, and acceleration sensors. Because pressure sensors and acceleration sensors are used in occasions (such as oil and gas logging, missile guidance), they usually allow higher costs, so they have been developed relatively quickly. These two types of quartz resonant sensors integrate the resonator and the surrounding structure, which greatly eliminates the influence of the surrounding structure on the force-frequency characteristics of the resonator, thereby ensuring relatively high precision of the sensor. However, the use of force sensors (such as weighing) often requires the sensor to be cheap, reliable, and at the same time require high precision and the possibility of mass production, which undoubtedly hinders its development. In order to meet the above requirements of the force sensor, a low-cost, combined structure quartz resonant sensor has been developed, such as the force sensor disclosed in Chinese patent application 95104981.X (publication number CN1113006A). However, because the sensor structure uses a single diaphragm to support the crystal, the stability of the sensor is poor, and its accuracy and range are also limited. In addition, the connection between the sensor components, such as the connection between the positioning diaphragm and the pressure block, the connection between the crystal and the pressure block and the pad, etc., has a great influence on the stability of the sensor, and it is easy to cause a large creep of the crystal. , making the sensor vulnerable to damage. Although the disclosed sensor of U.S. Patent US PatNo.3891870 adopts a double-diaphragm structure, because the thickness of the diaphragm on it is only 0.003 inches, it is very thin, so it can only play the role of sealing, and there is still a problem of unstable support. question.

The purpose of the present invention is to provide a quartz resonant force sensor with small creep, good stability, high precision, large measuring range and long service life for the above-mentioned defects in the prior art.

The high-stability quartz resonant force sensor of the present invention includes an electrode, an upper anvil, a quartz resonator, a lower anvil and a housing, and the bottom of the upper anvil and the upper part of the lower anvil are respectively provided with concave holes with a width slightly greater than the thickness of the resonator. Slots for securing the resonators. The resonator is supported in the housing of the sensor by the upper anvil and the lower anvil, and the external force F generates radial pressure on the resonator through the upper and lower anvils. The feature of the present invention is: the position of the upper anvil is limited by the double-diaphragm support structure composed of the diaphragm and the upper support plate, a cylinder is used to connect the diaphragm and the upper support plate, and the components are all connected by adhesives. catch.

The upper supporting plate of the present invention plays a supporting role, and its thickness is greater than 0.15mm, and is 0.15-2mm. The glue used for bonding components is glue with a glass transition temperature greater than 30°C, and the higher the temperature, the better.

Because the present invention adopts the double-diaphragm support structure and uses glue with a higher glass transition temperature to bond parts that need to be connected, the support conditions of the resonator are more perfect, and the hysteresis and creep of the sensor are significantly reduced. In the process of force measurement, the stability and precision of the sensor are greatly improved, especially the fatigue life is greatly extended.

Further illustrate the present invention below in conjunction with accompanying drawing.

Fig. 1 is a schematic diagram of the structure of the present invention.

Fig. 2 is the right side view of Fig. 1 .

Fig. 3 is a structural schematic diagram of another embodiment of the present invention.

In the figure 1-electrode, 2-housing, 3-lower anvil, 4-resonator, 5-upper anvil, 6-diaphragm, 7-coupling column, 8-gasket ring, 9-upper support plate, 10-protection Cover, 11-steel ball, 12-adjusting ring, 13-screw.

Example 1:

The structure of the quartz sensor of this embodiment is shown in FIG. 1 . Sensor 4 adopts a symmetrical incomplete disc structure, and the vibration is in the thickness-shear mode. Considering the force sensitivity as large as possible and the best frequency-temperature characteristics, the resonator adopts the AT-cut type, and the force direction is selected at ψ = 0 aspect. The resonator 4 is supported in the housing 2 of the sensor by the upper anvil 5 and the lower anvil 3 , and its electrode leads are welded to the upper end of the electrode 1 , and are led out of the housing by two legs of the electrode 1 . The lateral position of the upper anvil 5 is limited by the support structure formed by the diaphragm 6 and the upper support plate 9. The thickness of the upper support plate is 0.18 mm, the thickness of the diaphragm 6 is about 0.2 mm, and a column is used in the center of the diaphragm 6 and the upper support plate 9. The body 7 is connected, and the position of the lower anvil 3 is limited by the housing base. The bottom of the upper anvil 5 and the upper part of the lower anvil 3 respectively have grooves with a width slightly larger than the thickness of the resonator 4 for fixing the resonator so that the resonator can be vertically fixed in the sensor. H610 is used between the cylinder 7 and the support plate 9 and the diaphragm 6, between the upper anvil 5 and the diaphragm 6, between the resonator 4 and the upper anvil 5, the lower anvil 3, and between the lower anvil 3 and the base. This strong bond, low creep strain adhesive has a glass transition temperature of 30°. The measured force F is applied to the upper anvil 5 and transmitted to the resonator 4 through the steel ball 11 centered in the tapered blind hole on the upper part of the upper anvil. In addition, in the structure, in order to prevent the sensor from bearing unexpected loads, a protective cover 10 is also added on the upper support plate 9 . Table 2 is the performance data of each stage of the fatigue test of the sensor subjected to transverse pulsating load when the distance between the diaphragm 6 and the upper support plate 9 is 1.5 mm. Table 1 is the test data of a single diaphragm with a thickness of 0.18 mm tested under the same conditions .m01, m02,...m13 in Table 1 and n01, n02,...n13 in Table 2 are the sensor numbers, a, b,...e are the tests after the sensor was fatigued by a transverse pulsating load of 1kg/hour The data, f...i are the test data after fatigue of the sensor subjected to a transverse pulsating load of 4kg/hour. It can be seen from the table that after the same fatigue, the double-support structure sensor was not damaged, while 5 single-diaphragm sensors were damaged successively, and the damage rate reached 38%.

Example 2

The structure of the quartz sensor of this embodiment is shown in FIG. 3 . The structural difference between this embodiment and Embodiment 1 is that the diaphragm 6 and the supporting plate 9 are integrated with the connecting column 7, the steel ball 11 is located at the lower end of the connecting column 7 and above the upper anvil 5, and the thickness of the diaphragm 6 and the supporting plate are uniform. The glass transition temperature of the glue used for bonding the resonator 4 to the upper anvil 5 and the lower anvil 3 is 90°C. Table 3 shows some of the properties measured by the sensor when it is loaded with 5kg, 131g, and 16kg. Data. It can be seen from the table that when the load is increased from 5kg to 16kg, the error of the sensor does not increase. It can be seen that this structure can expand its measuring range and be more stable.

Table 1 No. No. Date Sensitivity Linearity Hysteresis Repeatability Date Sf X(H _z ) Z(H _z ) C(H ₂ ) Remark m01am01bm01cm01dm01em01fm01gm01hm01i 96/12/12 351.6 1.1 0.5 2.096/12/13 350.6 0.6 1.0 0.096/12/14 350.2 0.8 0.0 0.096/12/16 348.9 0.4 1.0 1.096/12/17 349.9 0.4 0.5 1.096/12/18 350.3 0.6 1.0 1.096/ 12/20 350.4 0.5 1.0 0.096/12/21 349.6 0.6 1.0 0.096/12/22 349.9 0.5 1.5 2.0 m02am02bm02cm02dm02em02fm02gm02hm02i 96/12/12 346.5 0.5 1.096/12/13 346.2 0.3 0.5 1.096/12/14 345.8 0.0 1.096/12/16 344.5 0.2 0.5 1.096/12/17 345.5 0.5 1.096/12/18 345.8 0.1 0.5 1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/ 12/20 346.8 0.2 0.5 1.096/12/21 346.0 1.0 1.0 096/12/22 346.3 0.3 0.5 1.0 m03am03bm03cm03dm03em03fm03gm03hm03i 96/12/12 347.6 0.8 1.0 2.096/12/13 346.5 0.6 0.5 1.096/12/14 346.2 0.0 0.096/12/16 345.1 0.2 0.5 1.096/12/17 347.6 1.096/12/18 347.9 1.1 0.5 1.096// 12/20 348.6 0.8 0.5 1.096/12/21 348.1 0.8 1.0 1.096/12/22 347.8 1.2 0.5 2.0 Continued Table 1 m04am04bm04cm04dm04em04fm04gm04hm04i 96/12/12 349.5 0.7 1.5 2.096/12/13 349.3 0.4 1.096/12/14 349.5 0.5 1.0 1.096/12/16 348.2 0.6 1.096/12/17 349.0 0.3 1.096/12/18 349.3 0.5 1.096/1.096// 12/20 349.2 0.4 1.0 0.096/12/21 349.2 0.5 2.0 1.096/12/22 350.1 0.6 1.5 3.0 m05am05bm05cm05dm05em05fm05gm05hm05i 96/12/12 350.7 1.5 2.0 2.096/12/13 350.5 1.2 4.0 0.096/12/14 349.5 1.3 3.0 1.096/12/16 348.1 1.5 3.0 2.896/12/17 348.9 1.6 3.096/12/18 349.2 1.3 3.096 /096/096/096/096/096/10 1.096/096/096/096/096/096/096/096/096/096/10 1.096/10 1.096/10 12/20 350.3 0.8 2.0 0.096/12/21 349.2 0.5 2.0 1.096/12/22 349.1 0.7 1.5 2.0 m06am06bm06cm06dm06em06f ^* m06gm06hm06i 96/12/12 338.3 0.5 0.5 2.096/12/13 338.5 1.2 0.0 1.096/12/14 338.0 1.3 1.0 0.096/12/16 336.4 1.4 1.0 0.096/12/17 338.0 0.096/12/18 338.7 0.6 0.5 1.096//1.096/1.096/1.096/1.096/ 12/20 344.9 1.7 2.0 1.096/12/21 345.5 2.2 1.5 1.096/12/22 345.2 1.6 2.0 4.0 Broken (8100 times of fatigue) m07am07bm07cm07dm07em07fm07gm07hm07i 96/12/12 352.9 0.7 1.0 2.096/12/13 352.4 0.6 1.0 1.096/12/14 351.8 0.8 1.0 1.096/12/16 349.8 0.4 1.096/12/17 351.1 0.0 1.096/12/18 352.0 0.096//18 352.0 0.096// 12/20 352.3 0.3 1.0 0.096/12/21 352.0 0.2 1.5 1.096/12/22 351.3 0.3 1.0 0.0 Continued Table 1 m08am08bm08cm08d ^* m08em08fm08gm08hm08i 96/12/12 347.7 0.5 1.5 2.896/12/13 347.7 0.4 0.5 1.096/12/14 347.4 0.8 0.5 1.096/12/16 345.4 1.0 0.5 1.096/12/17 353.3 2.1 0.5 2.096/12/18 353.5 1.6 2.096/096/096/096/2.096/096/096/2.096/096/096/2.096/096/2.096/096/2.096/2.096/096/2.096/096/2.096/2.096/096/2.096/096/2.096/096/1.6 12/20 354.7 2.4 1.5 1.096/12/21 354.1 3.4 3.5 8.096/12/22 354.5 5.5 4.0 2.4 Broken (4860 times of fatigue) m09am09bm09cm09d ^* m09em09fm09gm09hm09i 96/12/12 358.5 0.9 1.0 2.096/12/13 356.9 1.4 0.096/12/14 356.6 1.3 0.5 1.096/12/16 354.6 1.5 1.5 1.096/12/17 358.4 2.6 096/12/18 359.1 3.1 0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 2.096/0.5 12/20 360.2 2.5 2.0 5.096/12/21 362.8 3.8 2.0 1.096/12/22 363.1 2.5 2.5 1.0 Broken (4860 times of fatigue) m10am10bm10cm10dm10e ^* m10fm10gm10hm10i 96/12/12 353.0 0.9 1.5 4.096/12/13 352.2 0.6 1.5 1.096/12/14 349.9 1.3 3.0 1.096/12/16 348.6 1.1 2.0 0.096/12/17 350.3 0.9 2.096/12/18 353.8 3.2 2.096/096/096/096/096 12/20 354.9 2.1 3.0 1.096/12/21 355.1 2.0 3.5 2.096/12/22 356.7 3.6 6.0 2.8 Broken (fatigue 6480 times) m11am11bm11cm11dm11em11fm11gm11hm11i 96/12/12 348.6 1.8 1.0 2.096/12/13 348.9 0.9 1.0 1.096/12/14 349.5 2.0 2.0 2.096/12/16 347.3 1.0 1.096/12/17 348.8 0.9 2.0 1.096/12/18 350.2 0.096/1.096//18 350.2 0.096/ 12/20 350.2 0.7 1.0 1.096/12/21 349.5 0.9 0.5 1.096/12/22 349.2 1.2 1.5 4.0 Continued Table 1 m12am12bm12cm12dm12em12fm12gm12hm12i 96/12/12 347.8 0.8 1.5 2.096/12/13 348.5 0.8 1.0 2.896/12/14 348.1 0.6 0.6 0.5 2.096/12/16 345.8 0.4 1.096/12/17 346.9 0.2 1.096/12/18 347.2 0.3 1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/12 12/20 347.4 1.1 0.5 1.096/12/21 346.1 0.9 0.5 2.096/12/22 346.5 0.1 0.5 1.0 m13am13bm13cm13dm13em13f ^* m13gm13hm13i 96/12/12 354.1 0.8 1.5 1.096/12/13 353.9 1.0 2.5 1.096/12/14 353.4 0.5 2.0 0.096/12/16 351.3 1.0 0.096/12/17 353.6 0.6 1.5 2.096/12/18 354.8 0.9 2.0 1.096/096/096/1.096/096/096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/12 12/20 356.7 0.6 1.5 1.096/12/21 357.3 1.0 1.0 1.096/12/22 357.1 1.8 1.0 3.0 Broken (8100 times of fatigue) Table 2 No. No. Date Sensitivity Linearity Hysteresis Repeatability Date Sf X(Hz) Z(Hz) C(H ₂ ) Remark n01n01an01bn01cn01dn01en01fn01gn01hn01i 96/12/06 354.4 1.5 2.0 2.096/12/08 327.7 1.2 1.0 2.096/12/12 327.8 1.4 1.5 2.096/12/14 327.6 0.4 0.0 0.096/12/16 326.6 0.4 0.0 0.096/12/17 327.2 0.5 0.5 1.096/ 12/19 326.9 0.2 0.5 1.096/12/20 327.6 0.5 0.5 1.096/12/24 326.9 0.9 0.5 1.096/12/25 327.7 0.3 1.0 1.0 n02n02an02bn02cn02dn02en02fn02gn02hn02i 96/12/06 347.7 0.9 1.5 1.096/12/08 333.4 1.1 1.096/12/12 333.6 0.7 0.7 1.096/12/14 333.2 1.0 0.5 1.096/12/16 331.7 0.7 0.5 1.096/12/17 332.5 0.5 1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1 12/19 332.5 0.8 1.0 1.096/12/20 333.1 0.2 0.5 1.096/12/24 332.6 0.9 0.5 1.096/12/25 333.4 0.4 0.5 1.0 n03n03an03bn03cn03dn03en03fn03gn03hn03i 96/12/06 352.2 1.5 3.0 2.096/12/08 343.6 1.1 2.5 1.096/12/12 343.8 0.5 1.0 1.096/12/14 343.5 0.2 1.096/12/16 342.0 0.0 0.096/12/17 342.8 0.3 0.5 1.096//1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1s. 12/19 343.1 0.6 0.5 1.096/12/20 344.4 0.6 1.0 1.096/12/24 343.0 0.4 0.5 1.096/12/25 343.4 0.2 0.0 0.0 Continued Table 2 n04n04an04bn04cn04dn04en04fn04gn04hn04i 96/12/06 351.6 2.4 4.5 4.096/12/08 329.7 0.9 1.5 1.096/12/12 329.8 0.2 0.5 1.096/12/14 329.4 0.4 1.0 0.096/12/16 328.0 0.0 0.0 0.096/12/17 328.7 1.2 0.0 1.096/ 12/19 329.2 0.3 0.5 1.096/12/20 330.4 1.0 1.5 2.096/12/24 329.4 0.3 0.5 1.096/12/25 329.6 0.3 0.5 1.0 n05n05an05bn05cn05dn05en05fn05gn05hn05i 96/12/06 352.0 1.4 3.5 3.096/12/08 341.5 0.9 2.0 2.096/12/12 341.2 0.4 1.0 0.096/12/14 341.2 0.5 1.5 1.096/12/16 339.6 0.3 1.0 1.096/12/17 340.3 0.6 1.0 1.096/ 12/19 341.8 0.5 1.0 1.096/12/20 341.9 0.5 1.5 1.096/12/24 340.5 0.6 1.0 1.096/12/25 340.8 0.3 1.0 1.0 n06n06an06bn06cn06dn06en06fn06gn06hn06i 96/12/06 347.1 1.4 3.5 3.096/12/08 340.9 0.9 2.0 2.096/12/12 340.7 0.4 1.0 0.096/12/14 341.0 0.5 1.5 1.096/12/16 339.0 0.3 1.0 1.096/12/17 339.9 0.6 1.0 1.096/ 12/19 340.3 0.5 1.0 1.096/12/20 341.9 0.5 1.5 1.096/12/24 340.2 0.6 1.0 1.096/12/25 n07n07an07bn07cn07dn07en07fn07gn07hn07i 96/12/06 343.5 1.1 1.5 2.096/12/08 333.1 0.9 1.0 1.096/12/12 333.2 0.3 0.0 0.096/12/14 333.4 0.4 0.5 1.096/12/16 331.6 0.4 0.0 0.096/12/17 332.8 0.2 0.0 1.096/ 12/19 333.1 0.5 0.5 1.096/12/20 332.9 0.7 0.5 1.096/12/24 332.8 0.8 0.5 1.096/12/25 332.3 0.2 0.5 1.0 Continued Table 2 n08n08an08bn08cn08dn08en08fn08gn08hn08i 96/12/06 349.4 2.3 4.5 2.896/12/08 339.1 1.2 2.0 0.096/12/12 338.8 1.9 1.0 0.096/12/14 338.9 0.6 1.096/12/16 337.1 0.7 1.096/12/17 337.9 1.1 1.096// 12/19 338.7 0.8 1.0 1.096/12/20 338.5 0.4 1.0 1.096/12/24 337.9 0.8 2.0 1.096/12/25 337.6 1.1 1.5 1.0 n09n09an09bn09cn09dn09en09fn09gn09hn09i 96/12/06 345.8 2.1 2.5 1.096/12/08 320.9 1.3 1.0 1.096/12/12 321.1 0.9 0.5 1.096/12/14 321.0 1.2 0.2 1.096/12/16 319.0 0.5 1.096/12/17 319.7 1.5 1.096//1.096/1.096//17 12/19 320.4 1.3 0.0 0.096/12/20 320.2 1.8 1.0 1.096/12/24 320.0 1.1 0.5 1.096/12/25 319.6 0.7 0.5 1.0 n10n10an10bn10cn10dn10en10fn10gn10hn10i 96/12/06 338.2 0.9 1.5 2.096/12/08 320.6 0.6 0.0 1.096/12/12 321.2 0.0 1.096/12/14 320.8 0.7 1.096/12/16 319.4 0.2 1.096/12/17 319.3 0.0 1.096//1.096/096/ 12/19 320.2 0.2 0.5 1.096/12/20 320.3 0.2 0.0 1.096/12/24 320.4 0.5 0.5 1.096/12/25 319.1 0.3 0.5 1.0 n11n11an11bn11cn11dn11en11fn11gn11hn11i 96/12/06 349.4 0.9 1.0 2.096/12/08 321.9 1.1 1.0 0.096/12/12 321.1 0.9 0.5 1.096/12/14 322.1 0.8 0.5 1.096/12/16 320.4 1.096/12/17 320.8 0.8 0.5 1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1 12/19 321.6 0.6 0.5 1.096/12/20 321.4 0.9 1.0 1.096/12/24 321.3 1.0 0.5 1.096/12/25 321.0 1.2 2.0 1.0 Continued Table 2 n12n12an12bn12cn12dn12en12fn12gn12hn12i 96/12/06 351.9 2.0 3.5 2.096/12/08 328.4 1.1 2.0 2.096/12/12 328.8 2.3 1.5 1.096/12/14 328.2 0.6 1.5 1.096/12/16 326.5 1.3 1.096/12/17 326.8 0.9 0.5 1.096//1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1.096/1 12/19 327.6 0.5 0.5 1.096/12/20 327.4 0.5 0.5 2.896/12/24 327.5 0.8 0.5 1.096/12/25 326.2 0.5 1.0 1.0 n13n13an13bn13cn13dn13en13fn13gn13hn13i 96/12/06 343.4 1.9 0.5 1.096/12/08 330.6 2.3 0.096/12/12 331.1 2.4 0.096/12/14 331.9 2.1 0.096/12/16 329.3 2.5 1.096/12/17 330.5 2.2 1.096// 12/19 331.4 2.4 0.5 1.096/12/20 331.5 2.4 0.5 1.096/12/24 331.7 2.1 0.0 0.096/12/25 330.9 2.3 0.5 1.0 table 3

Claims (4)

1. A high-stability quartz resonant force sensor, comprising an electrode (1), an upper anvil (5), a resonator (4), a lower anvil (3), a housing (2), and the bottom of an upper anvil (5) and the upper part of the lower anvil (3) respectively have grooves with a width slightly larger than the thickness of the resonator (4) for fixing the resonator (4), and the resonator (4) is supported by the upper anvil (5) and the lower anvil (3) In the housing (2) of the sensor, the external force F generates radial pressure on the resonator (4) through the upper anvil (5) and the lower anvil (3), which is characterized in that: the position of the upper anvil (5) is determined by the diaphragm (6) and the upper support plate (9) are constrained by a double-diaphragm structure. A cylinder (7) is used to connect the diaphragm (6) and the upper support plate (9), and adhesives are used to connect the components bonding. 2. The high-stability quartz resonant force sensor according to claim 1, characterized in that: the thickness of the upper support plate (9) is 0.15mm-2mm. 3. The high-stability quartz resonant force sensor according to claim 1 or 2, characterized in that: except for the resonator (4) and the electrode (1), the rest of the components are made of metal, and the components are connected to each other. The glass transition temperature of the adhesive is above 30°C. 4. The high stability quartz resonant force sensor according to claim 3, characterized in that: the adhesive is H-610 or M-BOND610.

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