SU399896A1 - INDUCTIVE PHASE MOVEMENT SENSOR - Google Patents

Description

one

The invention relates to measurement technology and machine tool construction and can be applied in machine tools with programmed control, as well as in other automatic control systems as a feedback sensor.

Displacement sensors are known which contain a flat short-circuited winding deposited on a dielectric base in the form of conductive lines. With respect to this winding, flat indicator windings are displaced, displaced from one another by a quarter of a step and consisting of a row of sections.

However, these sensors require a highly stabilized voltage and a sophisticated electronic reading circuit. In addition, the winding of their measuring line must be connected to the measuring circuit. This complicates the operation of the machine with large movements of the machine organs (for example, on the order of several meters), since it requires the presence of sliding contacts or other structural complications, which reduces reliability and reduces the speed of movement of the ruler.

The purpose of the invention is to create a displacement sensor, insensitive to supply voltage fluctuations, having a simple electronic circuit, and also to exclude the galvanic connection of the measuring range with the power source of the windings and to increase the reliability and speed of devices operating with the sensor.

To accomplish this, the indicator winding is made in the form of three sectioned windings, the outputs of the sections of which are connected to ohmic resistances and form a series of phase-shifter units connected in series. Inputs windings indicator

the rulers are connected to a source of reference voltage. When moving the indicator bar relative to the measuring step, the phase of the signal at the output of each of the three windings changes by 360 °. These windings are connected

with a logic circuit that removes the signal from only one of the two windings and uses the phase of the signal of the third winding to determine the moment of switching of the first two windings. This ensures that the phase of the signal at the output of the sensor changes from 0 to 360 ° when the indicator bar moves half a step. Next, the windings are switched, and moving another half a step at the device output again causes a smooth change

phases from O to 360 °.

Such an embodiment of the sensor makes it possible to exclude contacts (galvanic connection) of the measuring range with the sensor circuitry. This advantage can be used if the indicator line

perform a fixed motion, and the measuring ruler is connected with the movable parts of machine tools, the movement of which must be measured.

FIG. Figure 1 shows the sensor ruler; in fig. 2 - indicator line; in fig. 3 is a block diagram illustrating the connection of the windings and all sensor assemblies; in fig. 4 illustrates the dependence of the phase of the signal at the output of the windings of the sensor indicator line on the displacement; in fig. 5 is a vector diagram for one section of any of the windings of the indicator array, explaining the occurrence of a phase angle between the input and output voltages; in fig. 6 - timing diagrams explaining the operation of a logic device; in fig. 7 - logical device circuit is deployed.

The sensor consists of a fixed measuring ruler 1 (FNG. 1), made in the form of a dielectric base 2 with a winding 3 applied on it in the form of conductive lines leading to the clamp g, winding 3 (the input and output of which are connected by a conductive line) moving indicator line 4 {fig. 2). Three windings 6, 7, and 8 are applied on the insulating base 5 of this line, the conductive lines of which follow with pin g. The winding 7 is shifted by 1/4 g, and the winding 8 is shifted by 1/2 g relative to normal C, which is expressed as ig + l / 4g and n2g + l / 2g, where ni and 2 are integers. Each of the windings consists of successive sections, each having five conclusions (branches).

Winding 6 has pins from 9 to 13, winding 7-c 14 to 18, winding 8-c 19 to 23.

Resistors 24-27, 28-31, and 32-35, respectively, are connected to these pins (Fig. 3). Thus, resistance is attached to the output of each section. The inductance and resistance in series are the phase shifter link. Thus, all windings with resistances connected to them form each four phase-shifter links connected in series. The inputs of the windings (9, 14 and 19 of Fig. 3) are connected to the input voltage UB-H, which is also fed to the input of the phase shifter. The outputs of the windings (13, 18 and 23 of Fig. 3), from which the voltages t / out t / Bbix2 I are removed (7, are connected to the inputs of the logic device 36, one of the inputs of which is also connected to the output of the phase rotator 37. To the outputs of the logic device 37 and 38, reference pulses and measurement pulses are output, carrying information about the measured displacement.

FIG. 7 shows the logic device 36 in expanded form. It consists of Schmidt triggers 39-42, drivers 43-45, inverter 46, triggers 47 and 48, a matching circuit 49 and 50, and an assembly circuit 51.

The sensor works as follows.

In the initial position, when the rulers 1 and 4 are fixed relative to each other, winding 6, 7 and 8 of the ruler 4 flows a current J. whose magnitude at the outputs 13, 18 and 23 revolutions (Fig. 3) depends on the inductance of the windings In turn, it depends on the magnitude of the magnetic coupling MI, Mg and M3 between the short-circuited winding 3 of the ruler 1 and the windings 6, 7 and 8 of the ruler 4. The magnitude of the magnetic coupling depends on the mutual position of the rulers and changes when moving from some mini. small to some maximum value.

Consider the phase rotation on the example of the winding 6. The current flowed through the first section of the winding and connected to it in series

resistance 24 causes a voltage drop Az, - / and R-1, respectively, on the inductance of the section and on the ohmic resistance 24 connected to the output 10 of this section. Here, XL is a 1.f1.-reactive component of the phase-shifter link, L is the section inductance depending on the magnetic coupling Mi, and w is the cyclic frequency of the input voltage t / nx- The output voltage of the 10 link of the phase-shifter can be expressed as the difference of vectors t / Bx and (). This is depicted in the vector diagram (Fig. 5). As can be seen from the diagram, the outflow at the output of the link of the phase shifter lags in phase from the input voltage t / ax by an angle f. The phase of nanoparticle taken from the output of one phase-shifting link can vary from 0 to 90 electrical degrees as the inductance of the sector changes from zero to infinity. As can be seen (Fig. 5),

X, IcuL

cp arctg- -z: iarctg-.

it is assumed that the resistance is the sum of the ohmic resistance of the wiring of the section itself and the external resistance 24. As can be seen from the formula, the phase f of the output voltage does not depend on the amplitude of the input voltage.

This relationship for f has sufficient linearity only for small inductance changes. In order to obtain a linear relationship for the entire range of inductance changes, the value of R for each link is chosen such that the maximum phase angle f corresponds to a sufficiently linear portion of this dependence. At the output 13 of the winding (with equal values of inductance of each section and resistances 24, 25, 26, 27) the phase of the signal will be shifted by the value of Pf, where n is the number of links of the phase shifter. This reasoning is also applicable to windings.

7 and 8. Suppose that in this initial position of the rulers the signal at the output 13 of the winding 6 lags behind, and the signal at the output of the winding 23

8 surpasses the signal at output 18 of winding 7 by 180 °. When this phase shifter 37 is configured so that in the initial position, the phase of the signal / OPS at its output coincides with the phase signal

at output 18 of section 7. Suppose that the number of sections of windings 6, 7 and 8 (which in Fig. 2 and Fig. 3 is conventionally taken to be four), as well as the value of external resistances connected to their outputs, are chosen so that If the indicator bar was moved by half a step (g / 2), the phase of the signals at the outputs of the windings would change by 360 ° with respect to the voltage / res. With this spatial mixing of the windings, this will be described using graphs 52, 53, and 54 (Fig. 4a). The logic device of the sensor operates in such a way that only the descending branches of the ab and cd graphs 52 and 54 corresponding to the signals (/ out1 and / out, and the signal pmx2 (plot 53 in fig. 4a)) are used to determine the movement which of the two windings 6 and 8 the movement data is to be taken from, which are then output to the output 38 of the logic device 36 as a phase shift of the pulses at this output relative to the reference pulses at the output 37. In the case of a signal at the output of the winding 7 ( "Outg) is ahead in phase with the Uou drive (section 00 in Fig. 4, a), the phase of the pulses at output 38 is determined by the phase of the signal bw (plot av schedule 54 and the section OOi in Fig. 4.8), and when the signal Pwc falls behind the signal f / on (section Oi02 in Fig. 4, a) then the phase of the pulses at the output 38 (Fig. 3) is degraded by the phase of the t / Buxi signal (section cd of the graph 52 and the section Oi02 in Fig. 4, b). / 2 corresponds to a phase change of the output signal of 360 ° (FIG. 4, c).

Consider the operation of logic device 36 at a certain offset Xi of the indicator line (Fig. 4, a) relative to the measuring. The magnitude of the magnetic coupling, Aiy and L4h, corresponds to this displacement, which is different from the magnitude of the coupling in the initial loop. coming to life. At the same time, the signals / pyx2 and 17exit are ahead of the signal {7opnaf2Ifz, respectively, according to f., Respectively (Fig. 4a), and the signal f / Buxi is lagging behind it in phase by the phase angle rp |. The X-shift corresponds to the time diagrams of these signals (Fig. 6a, d, b, and c), shown with the same amplitudes. These signals through the inputs 55, 56, 57 and 58 (Fig. 3 and 7) of the logic device arrive at the inputs of the Schmidt flip-flops 39, 40, 4l and 42 (Fig. 7), at the output of which rectangular signals are generated (Fig. Qh , f, i and I respectively). At the output of the Schmidt trigger 40, an inverter 46 is connected, producing a square signal (Fig. 6g). The signals from this flip-flop and inverter are fed to the trigger inputs S of the flip-flops 47 and 48, respectively. As you can see (Fig. 7), trigger 47 can be triggered when the signal from trigger 40 coincides with the output signal of trigger 42 with an open trigger 48, the zero arm of which is connected to the same input 5 of trigger 47. Trigger 48 can trigger if the signals from the inverter coincide 46 and from the Schmidt trigger 42, as well as in the absence of a prohibitory signal from the output of the zero arm

trigger 47. Therefore, at offsets corresponding to section 60 | (which is also valid for offset Xi), when the signal (7out2 ahead of the f / on signal at the very beginning of the signal period Uou coincides signals from Schmidt triggers 40 and 42, trigger 47 is triggered and prevents triggering of trigger 48. From the trigger edge of the trigger from 42 trigger using shaper 45 are formed

rectangular pulses (Fig. 6), which are output to output 37 (Fig. 3 and 7) as reference pulses, as well as for resetting flip-flops 47 and 48 through the inputs R to zero. In this case, only the trigger that is dropped to zero is

this item is not set to one. From the trailing edge of the pulses from the Schmidt flip-flops 39 and 41, short pulses are generated, which, via the matching circuit 49 and 50 and the assembly circuit 51, are outputted to

(Fig. 3 and 7) as measuring pulses. At offset Xi, the coincidence circuit 49 is opened by enabling signals (FIG. 6, t) of the ridge arm of the trigger 47, and the circuit 50 is closed, therefore the signal from the coincidence circuit 49

(Fig. 6) at the exit 38 corresponds to the rear

the front of the signal from the trigger Schmidt 39, and the phase

F4 pulses from the scheme sov-papi 49 (figure 4, and

and 6) is proportional to the displacement of Xi.

As the movement increases to

. the phase fz of the signal / gx will change according to the law corresponding to the section of the graph AB (Fig. 4a), while the phase of the measurement pulse will vary according to the law corresponding to the section OOi of the graph 4ff. At offsets, the signal L ,,,, iv2 lags behind the signal Lon and therefore, at the beginning of the non-iodode of the signal Uon, the signals from the output of the inverter 46 and the Schmidt trigger 42 coincide. Since the signals from the trigger

There are no Schmidt 40 and 42 at the beginning of the period, then the trigger 47 is quenched by pulses from the imaging unit 45, and the trigger 48 is triggered via the input S, mentioned by the coincidence of the pulses. At output 38, through the coincidence circuit 50 and the circuit

assemblies 51 are output pulses from the generator 44 output. When the phase of the t / Bbixi signal changes according to the law corresponding to section cd of chart 52 (Fig. 4a), the phase of the measuring pulse will change according to the law corresponding to section OiOj (Fig. 4o).

Obviously, a change in the range of the amplitude of the supply voltage will not affect the accuracy of the sensor, since it almost does not affect the accuracy of the Schmcht triggers.

P re d m e and z o b r c t n and n

An inductive phase displacement sensor, comprising a measuring ruler with a short-circuited winding applied to it and an indicator ruler with several windings printed on it, shifted one relative to another and made in a series of sections, characterized in that

simplify the device and improve its accuracy; resistors, a logic circuit and a phase shifter are inserted into it, with the output of each section connected to the corresponding resistor, the outputs of the indicator windings

the lines are connected to the inputs of the logic circuit, the other input of which is connected to the output of the phase shifter, the input of which and the inputs of the windings of the indicator line are connected to the terminals of the input voltage.

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