The structure of type displacement sensor optimizes differential transmission reach design of circuit of its number interface

The Paper Analyses The Principle Of Differential Transformer, in The Meantime, it Raise A Method Which Could Improve The Measurement Range By Optimizing The Structure Of The Instrument.

Provided With Different Exciting Signal, it Could Be Used To Measure The Other Mechanical Parameters.

The Digital Interface Circuit Is Designed At The End Of The Paper.

Key Words:dForeword of Ifferential Transformer;structure Optimizing;interface Circuit1 is in mechanical system, often need to undertake metrical to all sorts of mechanical quantities, because a lot of mechanical quantities can alternate,become displacement, reason chooses proper displacement sensor to be able to measure an a lot of mechanical volumes. Differential transformer changes mechanical displacement into with its proportionate voltage or voltaic signal, it is a kind of very convenience displacement detector. The configuration of differential transformer is more, but its job principle is basic however and same, it is the mutual inductance change that changes the change that is measured into transformer, transformer is primary coil inputs alternating voltage, secondary coil criterion the induction gives electromotive force. Optimize through the structure, differential transformer can be measured 0.

The mechanical displacement of 500mm of ～ of 01 μ M, have measure precision tall, sensitivity tall, structure simple, function is reliable wait for an advantage. The basic structure of 2 differential transformer is with transformer of differential of snail canal form exemple, introduce the main job principle of differential transformer. If the graph is shown 1 times,snail manages the construction of form differential transformer. It by primary coil P, s1 of two secondary coil, S2 and insert coil center cylindrical core B composition, its configuration has 3 paragraphs of type and two paragraphs of branch of type again. Graph principle of structure of transformer of differential of form of 1 snail canal (A) 　 of 　 of 　 of 3 paragraphs of type (B) 　 of 　 of 2 paragraphs of type (if the coil join of transformer of differential of graph of C) n principle pursues 1c place is shown. Secondary coil S1 and S2 reversal sex join. After the Ui of sine alternating voltage that increases some frequency when primary coil P, secondary coil produces inductive voltage to be U1 and U2, their size and core are concerned in the position inside coil. U1 and join of U2 reversal sex get outputting voltage U0. When core is located in coil center position, u1 ＝ U2, u0 ＝ 0; Move up when core when (1c) seeing a picture, u1 ＞ U2, u0 ＞ 0, criterion M1 is big, m2 is small (M1, M2 is) of coefficient of mutual inductance; When core moves downward (1c) seeing a picture, u1 ＜ U2, u0 ＜ 0, criterion M1 is small, m2 is big. When position of core deviate center, output voltage U0 the size as position of core deviate center, u1 or U2 increase gradually, mobile way is different, phasic differ 180 ° , if pursue,2 are shown. Accordingly, the volume that measures an output voltage and phasic the distance that can know core is mobile and direction. Graph the restriction that the structure of 3 sensor optimizes the characteristic curve of voltage of output of 2 differential transformer and working principle accepts a structure, transformer of differential of 3 paragraphs of type can be used at measuring small displacement only (10 ～ 20mm) , make a bit to the structure of transformer of differential of two paragraphs of type fluctuant, can satisfy the requirement that measures bigger displacement, its structure is shown 3 times like the graph. Graph structure of sensor of displacement of 3 long distances 1.

Core club 2.

Secondary coil 3.

Bakelite is in charge of 4.

Secondary coil of primary coil winding 2 circle closely in core club equably 1 on, this coil presses differential means to join by two groups of or so winding with identical measure of line means, v/LIT all over the ground number, structure and become, inductive signal is outputted by two terminal of C, D, core can be in charge of the 3 excitation coil that go up at be being circled in bakelite relatively 4 or so activity. Set excitation electric current to be: I (T) T (1) of ω of Iacos of ＝ I0 ＋ criterion voltage of two upright output is C, D: (2) among them Ml and Mr are the mutual inductance between or so winding and former edge winding respectively. When core is located in intermediate position, criterion M0 of ＝ of Mr ＝ Ml (3) if shift of core towards the left is apart from X, criterion M of Δ of ＋ of Xl ＝ M0 (4) and Mr ＝ M0 - Δ M (5) circle because deputy edge winding is even closely, because this has KmX of Δ M ＝ (6) type (3) ～ (6) generation enters type (2) , (7) can see U0 is comprised by 3, namely U03 of ＋ of U02 of ＋ of U0 ＝ U01 among them U01 of 　 of 　 of T of ω of ω Sin of U03 ＝ 2KmXia is dc heft, and the Dt of speed Dx ／ of direct ratio Yu Tiexin, because this can be used this at measuring speed; U01 is cosine heft, u02 is sine heft, the displacement X of Yu Tiexin of its amplitude direct ratio, and the bag in the amplitude of U02 contains ω , as a result of ω ＝ 2 π F, and F is compared normally big, so U02U01, because this is in type (oversight of U01 of 7) lieutenant general is dropped, not big to measuring a result to affect. Apparent, if dc heft is connected only in excitation coil, criterion the output of differential transformer can use the rate that measures core; If communication heft is connected only in excitation coil, criterion the output of differential transformer can be used measure displacement; If be connected at the same time in excitation coil,hand in, dc signal, criterion the output of differential transformer can is opposite of course speed, displacement undertakes metrical at the same time, have differential operation to speed signal, still can get acceleration signal. The place on put together is narrated, the excitation electric current that differs through bringing to bear on, differential transformer can be used at undertaking metrical at the same time to many mechanical parameter, become a kind practical muti_function measure an instrument. Design of circuit of 4 practical interface can be seen by afore-mentioned analysises, when the input is cosine signal, output is sine signal, its amplitude and mechanical displacement become direct ratio, to get the amplitude information of a need, the measurement of sensor interface circuit is comprised by place of the following parts commonly, if pursue,4 are shown. Graph 4 differential transformer measures interface circuit block diagram to pursue 4 in, LZX1 is demodulator of complete wave Xiang Min, the signal that it outputs sensor makes be outputted after complete wave commutate, repass is low connect filter, filter divides the high frequency signal that introduces when modulation, gotten dc signal passes enlarge, OK and direct drive records appearance, perhaps pass changeover of A ／ D, in inputting the computer, undertake a number show or control, in order to achieve the goal that to be being measured the athletic condition of the object has real time monitoring. The ram displacement that controls gear-shaping machine for logarithm undertakes metrical, we made the journey be the sensor of 0 ～ 25mm according to afore-mentioned principles, measure data to express place to show as follows. Watch displacement sensor measures data displacement (Mm)U0 (V) displacement (Mm)U0 (V) 20.

2-2-0.

240.

4-4-0.

460.

6-6-0.

680.

79-8-0.

8100.

99-10-1.

0121.

19-121.

19141.

39-14-1.

4161.

59-16-1.

59181.

79-18-1.

79201.

99-20-1.

99222.

19-22-2.

18242.

39-24-2.

38262.

57-26-2.

What 57 　 measure a result to show sensor is nonlinear degree be less than 1% , sensitivity is more than 15mv/mm, can satisfy use requirement. When the design measures interface circuit, the AD2S93 of chip of interface of number of transformer of low power differential that still can use American AD firm, it can finish the signal modulation of differential transformer to work not only, and still can finish A ／ to D is changed and output digital signal with serial means, have but repeatability is good, remote measure, high accuracy, low power comsumption, degree of linearity is good wait for an advantage, special agree with nicety is measured. The interface of AD2S93 and differential transformer is shown 5 times like the graph, among them the output signal of differential transformer carries an input by A, B, when CS end is low n, DATA end measures output displacement the number of the correspondence of absolutely position place of the head to measure, the digital amount of changeover uses 16 output, include information of 13 digit word among them, 2 spill over information and a wrong message, the digital amount of output can pass the input that string together a mouth in the computer. Graph circuit of interface of 5 differential transformer transformer of 5 conclusion differential is OK measure the machine such as displacement, speed, acceleration changeover to become telegraphic name, through undertaking to its structure circuit is designed optimizing reaching interface, can expand measure range, realize digital output, it is the mechanical displacement measuring instrument of a kind of convenient, reliable, economy. CNC Milling CNC Machining