CN1082183C - Quartz resonance force/weighing sensor - Google Patents

Abstract

The present invention belongs to the technical field of measuring instruments. The present invention comprises a quartz resonator used for measuring force, a referential resonator for temperature compensation and a parallelogrammic frame which is composed of a flexible hinge composed of four dual-surface circle arcs, wherein the frame is also provided with a pressure beam and a supporting beam which are parallel to each other, and the referential resonator is positioned in a positioned free from force in the frame; the quartz resonator for measuring force is installed between the two parallel beams. The present invention has the advantages of few components, few error sections, simple assembly, good linearity, high stability, small hysteresis, quantitive output of frequencies, easy processing of microprocessors, low power consumption, electricity supply with direct current and low voltage, etc.

Description

Quartz resonance force/weighing sensor

The invention belongs to the surveying instrument technical field, the quartz resonance force/weighing sensor structural design that particularly a kind of elastomer structure that is made of flexible hinge and quartz resonator are formed.

Force sensor applications is very extensive, and manufacturing technology is also ripe relatively.Common force transducer has resistance-strain type, piezoelectric type, resonant mode etc. several, and the most ripe and most widely used is resistance-strain type.Also be most widely used with resistance-strain type in the electronic scale field, resonant mode has development faster in recent years because of its good stability, digital output, resolution height.

Resistance-strain type comprises metal strain chip and semiconductor strain formula.The metal strain formula is the longest a kind of force transducer of applicating history.The characteristics of resistance-strain type are that dynamic perfromance is good, version is simple and easy to use, therefore weigh, aspect such as dynamometry all obtained to use comparatively widely.But this sensor will use tackifier to paste foil gauge, so there be creep and the hysteresis that causes by tackifier, and be not suitable for producing in batches, and shortcomings such as zero point, sensitivity drift.When being connected with microprocessor, carry out the A/D conversion to the simulating signal of output, increase cost, and reduced the reliability and the response speed of sensor.

Resonance type force sensor mainly is that type vibration wire and quartz resonance etc. are several.Its common characteristic is with periodic accurate digital signal output, promptly is convertible into microprocessor through simple digital circuit and is easy to the frequency digital signal that receives and handle; Higher sensitivity, resolution and stability are arranged; Antijamming capability is strong, is suitable for long Distance Transmission.Except that quartz resonance, other several sensors are all comparatively complicated, and are higher to the performance requirement of manufacturing, assembling and material in this class sensor.

Quartz resonance force/weighing sensor is modal to be combined type, utilizes fixedly quartz resonator of drum type brake shell and metallic membrane, and being delivered on the quartz resonator by dynamometry.Its advantage as previously described, and cost is very low, but major defect is to form that link is more, assembling is comparatively complicated, precision is not high.

The objective of the invention is to provides a kind of quartz resonance force/weighing sensor of new structure for overcoming the weak point of prior art.It is to utilize the power frequency effect of quartz resonator resonance frequency to the power sensitivity, by the fixing quartz resonator and being delivered on the quartz resonator of elastic body by dynamometry, the resonance frequency that causes quartz resonator produces corresponding the change, by the change amount of measuring resonance frequency power or weight is measured.Have that building block is few, the error link is few, assembling is simple; Good linearity, stability be high, it is little to lag behind; The digital signal that can obtain being fit to microprocessor processes is handled in frequency quantity output through simple digital circuit; Low in energy consumption, advantages such as dc low-voltage power supply.

The present invention proposes a kind of quartz resonance force/weighing sensor, comprise measuring quartz resonator and as the reference resonator and the circuit thereof of temperature compensation, it is characterized in that, also comprise a parallelogram lever, the horizontal both sides of this framework are respectively equipped with two flexible hinges of being made up of two-sided circular arc, the center of these four flexible hinges constitutes four summits of this framework, and this framework also is provided with two parallel pressure beam and brace summers; Said reference resonator places the place that do not stress in the framework, and said measurement quartz resonator is installed in the middle of said two parallel girders.

Above-mentioned said brace summer is a semi-girder, and the one end is connected with the framework flexibility or rigidity, and the other end is unsettled; Said pressure beam can be with said brace summer and becomes reverse semi-girder, and said measurement quartz resonator is installed in the middle of said two parallel girders and is positioned at the midpoint of said framework; Said pressure beam can be both-end and fixes, and an end and framework flexibly connect, the other end and frame rigidity or flexibly connect; Said pressure Liang Yeke is divided into not two parts on same horizontal line, is linked into an integrated entity by a vertical flexible hinge; Vertically the position of flexible hinge is in the midpoint of parallelogram lever; Said pressure beam also can constitute for the horizontal frame by framework, and said brace summer is located at this frame outside.

Stressed quartz resonator is installed in the midpoint of parallelogram if the employing double cantilever beam does not have vertical flexible hinge.

The said resonator circuit of the present invention can adopt conventional known circuits, is not described in detail in this.

Principle of work of the present invention is described below in conjunction with Fig. 1:

Flexible hinge 11,12,13,14 constitutes elastic body framework 1 among Fig. 1, the mid point O that is centered close to framework of these four flexible hinges, the effect of flexible hinge is to make amount of deflection that framework produces under by the effect of dynamometry and be directly proportional by the size of dynamometry, and guarantees on the sensor constant by the direction of dynamometry.Brace summer 4 is semi-girder EF, presses beam 5 to be made up of AB section and CD section, and continuous by the flexible hinge 17 that is positioned at the vertical direction that O order between these two sections, its A holds to being rigidly connected, and D holds to flexibly connecting.Measuring quartz resonator 2 is installed in semi-girder EF and presses between the CD section of beam, is installed on the AB section of pressing beam as the reference resonator 3 of temperature compensation.The effect of flexible hinge 17 is to eliminate the influence of framework transversal displacement to output quantity.When framework produced the amount of deflection of vertical direction under by the effect of dynamometry, B can produce horizontal displacement thereupon, and this can cause the transversal displacement of C end, thereby the output of sensor is exerted an influence, and this is more obvious when being influenced when big by dynamometry.The power and the displacement of 17 pairs of vertical directions of flexible hinge are rigidity, are flexible to horizontal power and displacement, therefore just guaranteed that the power of the vertical direction that B is ordered and displacement can be passed to the C point, and horizontal power and displacement can not be delivered to the C point by isolation.Flexible hinge 15 and 16 effect are that the amount of deflection of beam CD and beam EF is directly proportional with power, guarantee the linearity of sensor.

By following design, this quartz resonance force/weighing sensor can be only to power P sensitivity, and insensitive to moment W.If consider flexible hinge 17 is disconnected at the center O place, then the vertical beam on flexible hinge 12 and 13 the right will produce the clockwise corner of downward amount of deflection and 2a under the effect of moment W shown in the figure, as shown in the figure.Semi-girder AB should produce downward displacement with the A point like this, produce the corner of clockwise 2a again, this just might make that the O point does not produce any displacement by the position of selecting O to order rightly under the combined action of these two motions, be that the influence that moment W effect is produced can not pass to the CD beam by the O point, so sensor is insensitive to moment, this moment, the O point was exactly an elastomeric center of rotation under the W effect.To that indicated in the drawings when reverse in the moment direction, still have same result.Therefore make when being used for making electronic scale as LOAD CELLS when this sensor, can not produce position error.This is one of this sensor biggest advantage.Through calculating, can obtain when the center of O point, promptly at sensor $l_{\mathrm{AB}}=\frac{1}{2}{\mathrm{<figure-callout\; id="12"\; label="l"\; filenames="C9810303000072.png"\; state="\{\{state\}\}">l</figure-callout>}}_{11,12}$ The time moment to not influence of the output of sensor, sensor is to moment-insensitive.

Elastic body be delivered on the quartz resonator power be directly proportional by dynamometry, this scale-up factor is relevant with the material and the physical dimension of elastic body and flexible hinge.By changing the size of elastic body size and flexible hinge, can change the sensitivity and the range of sensor.For example increase the flexible hinge radius R or reduce flexible hinge center thickness t, meeting improves the sensitivity of sensor and reduces the range of sensor, on the contrary, reduce the radius R of flexible hinge or increase the range that flexible hinge center thickness t can reduce the sensitivity of sensor and improve sensor.

Sensor adopts the difference frequency of two identical quartz resonators as output signal, resonator 2 is stressed and resonator 3 does not stress, the frequency that the frequency of resonator 2 and 3 is carried out obtaining behind the difference frequency is as output signal, can reduce the frequency range of signal Processing like this, and because resonator 2 is identical with 3 characteristic, the common mode variations amount of two resonant frequencies that disturbing factor causes is offset behind difference frequency, thereby made the influence that is subjected to external interference (especially variation of temperature) zero point hardly of sensor.

The temperature coefficient of quartz resonator force sensitivity is different and different with the action direction (position angle of power) of external force.For the quartz resonator of AT cut type, when position angle during 40 ° of left and right sides, the temperature coefficient of force sensitivity is zero.Can certainly select the quartz resonator of other cut type for use.In order to improve range, can cut edge to quartz resonator.

Characteristics of the present invention are good linearity, little, good reproducibility lags behind; Zero point and sensitivity are not subjected to the influence (especially temperature) of external interference; Sensor is responsive and to moment-insensitive, therefore do not have position error when as LOAD CELLS manufacturing electronic scale to the power that adds the force; Adjust elastomeric physical dimension and can make the sensor of different ranges.In addition, this sensor is output quantity with the frequency, is fit to computing machine (microprocessor) and handles, and does not need the A/D conversion; Power consumption is very low, can power with dc low-voltage.

Brief Description Of Drawings:

Fig. 1 is embodiments of the invention one structural representations;

Fig. 2 is embodiments of the invention two structural representations;

Fig. 3 is embodiments of the invention three structural representations;

Fig. 4 is embodiments of the invention four structural representations;

The present invention designs four kinds of quartz resonance force/weighing sensor example structure, as Fig. 1-shown in Figure 4, is described in detail as follows respectively in conjunction with each figure:

Embodiment one structure as shown in Figure 1, flexible hinge 11,12,13,14 constitutes elastic body framework 1 among the figure, the center of these four flexible hinges constitutes four summits of framework, brace summer 4 is semi-girder EF, press beam 5 to form by AB section and CD section, flexible hinge 17 by the vertical direction at the mid point O place that is positioned at framework between these two sections links to each other, and its A end is for being rigidly connected, and D holds to flexibly connecting.The quartz resonator 2 that ergometry is used is installed in semi-girder EF and presses between the CD section of beam, is installed on the AB section of pressing beam as the reference resonator 3 of temperature compensation.The elastic body frame material of present embodiment is selected 40CrNiMo for use, also can select elasticity other material preferably for use, as 40Cr, 30CrMnSi, LY12 or LC4 etc.The resonator of selecting for use in the present embodiment is two kinds of AT cut type 3.579MHz and AT cut type 8.3MHz.The physical dimension of four flexible hinges is identical, for: R=4mm, t=1mm; l _11,12=60mm, l _11,13=60mm; Its range is 20Kq.

Embodiment two structures as shown in Figure 2, its structure is more succinct, flexible hinge 11,12,13,14 constitutes elastic body frameworks 1, brace summer 4 is semi-girders, the one end is connected with frame rigidity, the other end is unsettled; Pressing beam 5 is and 4 one-tenth reverse semi-girders of brace summer that one end and framework flexibly connect.Reference resonator 3 places the end of pressing beam 5, measures quartz resonator 2 and is installed in the middle of said two parallel girders.The physical dimension of four flexible hinges is identical, for: R=8mm, t=2mm; l _11,12=60mm, l _11,13=50mm; Its range is 60Kq.

Embodiment three structures as shown in Figure 3, the difference of its structure is that brace summer 4 is the semi-girders that place outside the framework, one end and framework flexibly connect, and do not press beam in the frame, but with the frame 5 of framework as pressing beams.Reference resonator 3 places the middle part of frame 5, and measurement quartz resonator 2 is installed in the framework right-hand member is pressed on the quartz resonator.

Embodiment four structures as shown in Figure 4, the difference of its structure flexibly connects for pressing beam 5 left ends and framework, right-hand member flexibly connects by two vertical flexible hinges and framework.

Claims (5)

1. quartz resonance force/weighing sensor, comprise measuring quartz resonator and as the reference resonator and the circuit thereof of temperature compensation, it is characterized in that, also comprise a parallelogram lever, the horizontal both sides of this framework are respectively equipped with two flexible hinges of being made up of two-sided circular arc, the center of these four flexible hinges constitutes four summits of framework, and this framework also is provided with two parallel pressure beam and brace summers; Said reference resonator places the place that do not stress in the framework, and said measurement quartz resonator is installed in the middle of said two parallel girders.

2. sensor as claimed in claim 1 is characterized in that said brace summer is a semi-girder, and the one end is connected with the framework flexibility/stiffness, and the other end is unsettled; Said pressure beam is to become reverse semi-girder with said brace summer, and said measurement quartz resonator is installed in the middle of said two parallel girders and is positioned at the midpoint of said framework.

3. sensor as claimed in claim 1 is characterized in that said brace summer is a semi-girder, and the one end is connected with the framework flexibility/stiffness, and the other end is unsettled; Said pressure beam both-end is fixed, and an end and framework flexibly connect, and the other end is connected with the framework flexibility/stiffness.

4. sensor as claimed in claim 3 is characterized in that, said pressure beam is divided into not two parts on same horizontal line, is linked into an integrated entity by a vertical flexible hinge; Vertically the position of flexible hinge is in the midpoint of parallelogram lever.

5. sensor as claimed in claim 1 is characterized in that, said pressure beam is made of a horizontal frame of framework, and said brace summer is located at this frame outside.

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