Type of meet an emergency force transducer

 

In all force transducer, type of meet an emergency force transducer application is most wide. It can apply at arriving from minimum very big move, the measurement of static force, and measure precision tall, its make dosage occupies the 90 ％ of force transducer gross to control about.

 

Type of meet an emergency the working principle of force transducer and pressure sensor of type of meet an emergency are basic and identical, it also is by stretch sensing element and the meet an emergency that are stuck on its piece composition. Type of meet an emergency the meet an emergency that force transducer transforms the force that be measured into stretch component above all, effect of recycle resistor meet an emergency measures a meet an emergency, measure the volume that exert oneself secondhand thereby. The configuration of stretch component has form of column form, canister form, annular, bridge, spoke form, S form to wait.

 

Meet an emergency piece decorate and receive bridge kind, have very big concern to heightening the sensitivity of sensor and the effect that remove harmful factor. According to bridge add those who decrease character and stretch component to get force quality, below the circumstance that sticks a positional license, can stick 4 or 8 meet an emergency piece, its position should be the place with stretch component the greatest strain.

 

Type of column form meet an emergency force transducer

 

Graph 1 gave out component of flexibility of common column form, canister form, bridge form and meet an emergency piece stick a way. Graph 1 (A) component of flexibility of the form that it is column; Graph 1 (B) component of flexibility of the form that it is a canister; Graph 1 (C) component of flexibility of the form that it is bridge.

 

Graph a few kinds of 1 stretch component and meet an emergency piece stick a way

 

Component of column form flexibility normally make it is cylindrical He Fangzhu form, use at measuring greater power. Maximum Cheng can amount to 10MN. When load is lesser (1——100kN) , to facilitate stickup meet an emergency piece and because load is prejudicial,be reduced or side direction component of force causes curve an influence, at the same time to heighten sensitivity, use system of open tubular column more. 4 meet an emergency piece stickup position and direction should assure to feel fore-and-aft strain two pieces among them, additionally two feel transverse strain (because fore-and-aft meet an emergency and transverse strain are each other,be retrorse change) , if pursue 1 (A) be shown.

 

Go up in elastomer when action of axial of cylinder of edge of F of the force that be measured when, its are fore-and-aft meet an emergency and transverse strain are respectively

 

 

In type, e is the stretch model quantity of material; S is the cut area of cylinder; μ is compared for the Poisson of material.

 

In be measured actually, the force that be measured is impossible as it happens the axes action along cylinder, and always become with axes one tiny angle or tiny prejudicial, this makes stretch cylinder besides sufferring fore-and-aft strength effect, still get transverse force and the action that bend quadrature, affect thereby measure precision.

 

Spoke type force transducer

 

 

The stretch component such as simple pillar, barrel type, Liang Shi is a basis stress and load become the relation of direct ratio to measure, they are existing a few weakness that overcome not easily.

 

To raise force transducer further function is mixed measure precision, requirement force transducer has fight prejudicial, fight side force and fight overload ability. 70 time begin 20 centuries to develop a shear stress sensor successfully. Graph the 2 structural diagram that are sensor of more commonly used spoke type shear stress.

 

Type of graph 2  spoke force transducer

 

Spoke type force transducer by annulus circle, annulus Gu, spoke and meet an emergency piece composition. Spoke is didymous and symmetrical ground joins round of circle and annulus Gu, be in when outside force action round of end panel on Gu and annulus when face of Gu lower end, rectangular spoke produces a parallelogram to be out of shape, if pursue 2 (B) be shown, form the shear strain that becomes direct ratio with outside force. This shear strain can cause two mutual and perpendicular when become 450 way with neuter axis to be being lost stress, pull by what shear stress causes namely stress and press stress, pull stress through measuring or press stress to be worth the size that is worth with respect to knowable shear stress.

 

Accordingly, in spoke type sensor, meet an emergency piece stick what become 45 degrees with shear stress locally, those who make it is experienced still is drawing is mixed reduce strain, but this meet an emergency is not apart from generation by the turn, basically arise by shearing force, this namely the main job principle of this kind of sensor. The advantage with this kind of the most outstanding sensor is to fight overload ability strong, can bear to decide the overload of span at the forehead severalfold. In addition, its fight the prejudicial, ability that fights side force stronger also, precision is in 0.1 ％ .

 

The type that press magnetism force transducer

 

Be in when iron magnetism material get of outside force pull, control function and when interiorly produces stress, the size that its guide magnetism rate can follow stress changes with direction: When getting pulling force, make those who use way guide magnetism rate increases along force, and in perpendicular reduce somewhat at guiding magnetism is led on the direction of active force; The metabolic as it happens that when press press master piece is used, guides magnetism is led is contrary. Phenomenon of this kind of physics is the effect pressing magnetism of iron magnetism material. This kind of effect can use Yu Li measure.

 

Graph sensor of the 3 type that press magnetism

 

The type that press magnetism force transducer is comprised by the component that press magnetism, orgnaization that send force commonly, if pursue 3 (A) be shown.

 

Among them the body is the component that press magnetism, it is folded by the chip of iron magnetism data of the starting a hole on its. The opening that 4 semmetry distributing rushs on the component that press magnetism, aperture 1 and 2 between circle have excitation winding W12 (primary winding) , aperture 3 circle with 4 have measure winding W34. (sub winding) , if pursue 3 (B) be shown.

 

Connect when excitation winding W12 have hand in change when electric current, the magnetic field of certain size produces in ferromagnetic. If do not have outside force action, criterion photograph of magnetic induction line distributings symmetrically to measuring winding plane, day of intensity of synthetic magnetic field is parallel at measuring the plane of winding W34, magnetic induction line not with measure winding W34 to hand in even, reason winding W34 does not produce inductive electromotive force, if pursue 3 (C) be shown.

 

Should have when compressing force F action to go up at controlling magnetism element, the distributinging graph of magnetic induction line happens be out of shape, no longer symmetrical at measuring the plane of winding W34 (if pursue 3 (D) be shown) , h of intensity of synthetic magnetic field no longer with measure winding plane parallel, have partial magnetic induction consequently line and measure winding W34 to intersect catenary, and on its the induction gives electromotive force. Active force heals big, the magnetic flux that makes chain heals much, inductive electromotive force heals big.

 

The output electromotive force of force transducer compares the style that press magnetism big, need not magnify again normally, after wanting to pass filter wave commutate only, can output directly, but the excitation power source that asks to have a stability. The type that press magnetism force transducer is measurable very great power, fight overload ability strong, can work below abominable condition. But frequency is answered not tall (1——10 KHz) , measure precision to be controlled in 1 ％ commonly, the type pressing magnetism that also has the new-style structure with higher precision force transducer. The branch serves as the heavy industry such as gold of commonly used Yu Ye, mine to measure power or say to weigh sensor, use on rolling mill for example measure generous force and in be being used in crane balance.

 

 

The type that suppress report force transducer

 

Sensor of the type that suppress report is the sensor that is based on piezoelectric effect. It is type of a kind of initiative report and sensor of Electromechanical changeover type. Its sensing element is made by the material that suppress report. The surface after the material that suppress report gets power generates charge. Amplifier of charge of this charge classics and the n that direct ratio becomes to get outside force at place after measuring circuit enlarge and commutation impedance are outputted. Sensor of the type that suppress report is used at measuring force and can alternate the physical quantity is not report that is force. Its advantage is frequency bandwidth, sensitivity simpler than tall, structure, job mixes a confusion of voices of tall, letter reliably weight is light etc. Defect is certain the material that suppress report needs moistureproof measure, and the dc of output answers difference, need uses circuit of tall input impedance or charge amplifier to overcome this one limitation. Use the data that suppress report (quartz the crystal, pottery and porcelain that suppress report) piezoelectric effect, the force that be measured changeover is the charge that becomes direct ratio with its to measure output;

 

Quartz crystal: Performance is steady, dynamic effect is good, mechanical intensity is high, linear range is wide, multi-purpose at high accuracy, a large number of Cheng are measured, MN-MN.

 

Press electric pottery and porcelain: Press piezocrystal of electric constant outclass, low-cost, use is extensive.

 

Basically use at trends to measure:

 

 

Zhen Xian type force transducer

 

Sensor of Zhen Xian type (Vibrating Wire Transducer) it is the syntonic type sensor that serves as sensing element with taut metallic bowstring. After deciding when the length of bowstring, its are inherent and oscillatory the change of frequency is measured can token bowstring place gets tensile bulk, pass corresponding measurement circuit, attainable the telegraphic name that becomes particular concern with pulling force. The relation of F of inherent and oscillatory frequency and tensile T is, the L in type is Zhen Xian’s length, ρ is the quality of unit chord. Zhen Xian’s material and quality affect the precision of sensor, sensitivity and stability directly. The function stability of tungsten filament, hardness, melting point and tensile strength are very high, it is commonly used Zhen Xian material. In addition, silk of steel wire of bowstring of usable still fiddle, high strenth, titanium regard Zhen Xian as material. Device of You Zhenxian of sensor of Zhen Xian type, magnet, clamp is comprised with orgnaization getting power. Join of fixed, one aspect of the matter is in Zhen Xian one aspect of the matter on orgnaization getting power.

 

 

Inchoate pressure sensor uses Zhen Xian formula namely. The Zhen Xian one aspect of the matter of this kind of sensor is fixed, another end is concatenate diaphragm is pressed to go up in stretch feeling. Of bowstring mid of a soft iron, in the magnetic field of the activator that park magnet and coil form. Activator holds Shi Zhenqi concurrently when suspending drive, or sheet sets Shi Zhenqi. When the job, zhen Xian is oscillatory below the drive of activator, the size of its vibration frequency and force of diaphragm place press press is concerned.

 

Shi Zhenqi gets oscillatory frequency signal through electromagnetism induction. Zhen Xian’s oscillatory incentive means has intermittence type and continuous two kinds. In intermittent and incentive means, use relaxation oscillator to give out incentive pulse, make through a relay the soft iron on bowstring of grip of coil electrify, magnet piece.

 

After incentive pulse stops, magnet is loosened, make Zhen Xian free and oscillatory. Produce inductive electromotive force namely in coil right now, its hand in frequency conversion to lead the inherent and oscillatory frequency that is Zhen Xian namely. Successive and incentive means can be divided again for voltaic law and electromagnetism law. Voltaic law serves as Zhen Xian equivalent LC loop is shunt-wound in oscillating circuit, make circuit the natural frequency oscillation with Zhen Xian.

 

Electromagnetism law uses two magnet of coil, regard incentive coil and Shizhen as coil respectively. After the inductive signal of coil is magnified, Shizhen sends to incentive coil to complement again oscillatory energy. To reduce sensor nonlinear the influence to measuring precision, the optimal job frequency that needs to choose moderate paragraph with setting prestressing force, or the differential type structure that uses the two side in feeling pressing film to set a Zhen Xian each.