JPS5856413B2 - Displacement position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a displacement position detection device that converts a mechanical displacement position into an electrical signal.

SUMMARY OF THE INVENTION An object of the present invention is to realize a device of this type that has a simple configuration and is capable of detecting a displacement position with high accuracy without being affected by ambient temperature or the like.

In the figure, 1 is a magnetostrictive wire made of linear magnetostrictive material such as Ni-8PANC, Ni, etc., and one end 11 of the magnetostrictive wire 1 is sized so that mechanical vibrations from the outside are not transmitted.
3, the distorted wave signal (
It is lightly supported so that the ultrasonic signal (ultrasonic signal) is reflected with reversed polarity.

Reference numeral 2 denotes a receiving means disposed at the other end (or near the end) of the magnetostrictive wire 1, and here an example is shown in which it is constituted by a coil wound around the magnetostrictive wire.

4 is an excitation means which is movably coupled to the magnetostrictive wire 1 and generates a strained wave signal (ultrasonic signal) within the magnetostrictive wire 1; It consists of a transformer 40 having an iron core, and an excitation coil 41 wound around the magnetostrictive wire 1 to which a signal is applied to induce a secondary coil of the transformer 40.

Reference numeral 5 generally shows a movable part to which a mechanical displacement is applied and moves in response to this mechanical displacement. move along.

os is an excitation pulse generator, and its output pulse pE is applied to the excitation means 4 via the magnetostrictive wire 1, and the flip-flop circuits F'F1. It is applied to the cent terminal S of FF2.

Both OPI and OF2 are comparison amplifiers, and comparison amplifier OP1 receives the signal from the receiving coil 2 and the positive reference voltage E.
s, and its output signal is sent to the Noritsubu flop circuit F.
It is applied to the reset terminal of F"1.

Comparison amplifier OP2 compares the signal from receiving coil 2 with negative reference voltage -Es, and its output signal is applied to reset terminal R of flip-flop circuit FF'2.

CK is an arithmetic circuit that manually processes two time width signals PW1 and PW2 obtained from flip-flop circuits FFI and FF2.

The operation of the apparatus constructed in this way will now be explained with reference to FIG.

First, when an excitation pulse pE is applied from the excitation pulse generator O8 to the magnetostrictive wire 1 as shown in FIG. 41.

When an excitation pulse is applied to the excitation coil 41, the position of the excitation coil 41 is pressed and an ultrasonic signal is generated inside the magnetostrictive wire 1 due to the so-called Joule effect, which propagates toward both ends of the magnetostrictive wire 1. 1. When the signal propagated to the right side from the excitation coil 41 reaches the position of the receiving coil 2, a signal as shown at e in Figure 2 is detected in the receiving coil 2 by the so-called Villari effect. Ru.

The signal propagated to the left side from the excitation coil 41 is reflected at the end face 11, returns through the magnetostrictive wire 1, reaches the receiving coil 2, and
The receiving coil 2 detects a signal as shown at 02 in the second figure.

The signal e1 generated by the ultrasonic signal directly propagating from the excitation coil 41 to the receiving coil 2 and the signal e2 generated by the ultrasonic signal reflected from the end face 11 and propagated with reversed polarity are mutually exclusive as shown in the figure. They have different polarities.

If it is assumed that an ultrasonic signal is generated within the magnetostrictive wire 1 at the same time as the excitation pulse pE is applied to the magnetostrictive wire 1, this ultrasonic signal is directly transmitted from the position of the excitation coil 41 to the receiving coil 2.
The time at which the bud reaches the position of tl and the excitation coil 41
The t2 at the bud that is reflected from the end face and reaches the position of the receiving coil 2 from the position can be expressed by the tlil) formula and the 2) formula. Speed of signal propagation L: Distance between end face 11 of magnetostrictive wire 1 and receiving coil 2 X: Distance between end face 11 of magnetostrictive wire 1 and excitation coil 41 Each set of flip-flop circuits F'FI and FF2 The terminal S receives an excitation pulse PE from an excitation pulse generator O8.
is applied, and these flip-flop 'circuits F
Due to this excitation pulse PEK, F1 and FF2 are brought into a set state as shown in FIG.

The comparator amplifier OP1 selects the positive polarity reception signal e1 detected first among the signals from the reception coil 2, and sets the flip-flop circuit FF1 to a reset state as shown in FIG. 2C.

Similarly, the comparison amplifier OP2 selects the negative polarity reception signal e2 from among the signals from the reception coil 2, and resets the Noritsu flop circuit FF2 as shown in FIG.

Therefore, a time width signal PW1 having a time width of tl and t2 is generated from the output terminals of the free lobe flop circuits FFI and FF2 as shown in FIG.

PW2 is obtained.

The arithmetic circuit CK includes each flip-flop circuit FF''l.

Time width signal PWI from FF2, PW2 is human power,
By performing calculations such as equation (3), the excitation means 4
That is, a signal Eo related to the displacement position X of the movable part 5 can be obtained from the output terminal OUT.

Regarding equation (3), since L is a constant value, the output signal Eo is a signal that is exactly proportional to the displacement position X of the movable part 5 and is not affected by the propagation velocity V%J.

If the arithmetic circuit CK is constructed from a digital arithmetic circuit, the output signal Eo can be easily obtained as a digital signal, and if the arithmetic circuit CK is constructed from an analog circuit, the output signal Eo can be easily obtained as an analog signal.

The displacement position detection device according to the present invention obtained in this way receives two types of propagation signals with one receiving means, and uses these two types of signals to perform calculations such as equation (3). Since the structure is simple, it has the advantage of being able to perform highly accurate displacement detection without being affected by the propagation velocity v8 of the ultrasonic signal as described above.

Another advantage is that if the excitation means 4 is constituted by the transformer 40 and the excitation coil 41, no special lead wire is required for supplying the excitation power.

Another feature is that it is not affected by changes in length due to linear expansion of the magnetostrictive wire 1 itself due to changes in temperature or the like.

That is, the linear expansion coefficient of the magnetostrictive wire 1 is α, and the temperature change is Jt.
Taking this into consideration, equation (3) is rewritten as shown below, and by calculating El t2 and performing tl+t2, the influence of the change in the length of the magnetostrictive wire 1 itself can be removed.

Additionally, the device configured in this manner can also eliminate the influence of changes in the degree of coupling between the excitation means and the magnetostrictive wires that occur as the movable portion 5 moves.

That is, the ultrasonic signals generated in the magnetostrictive wire 1 by the excitation means 4 and propagated to the left and right, respectively, are signals with approximately the same amplitude, and the receiving means 2 receives propagation signals with approximately the same amplitude, although with different polarities. do.

Therefore, the time width f,1, j2 of the signals from each flip-flop FFI, FF2 is determined by the change in the amplitude value of the propagation signal (the change in the amplitude value changes depending on the degree of coupling between the excitation means and the magnetostrictive wire). ) will also intervene in the same way.

Therefore, 1. This error can be canceled by performing the calculation of equation t(3), which includes 12 calculations.

Therefore, according to the device according to the present invention, the displacement position can be measured with high accuracy without being affected by environmental changes.

31 and 4 are configuration diagrams showing other examples of excitation means used in the apparatus of the present invention.

In the example shown in FIG. 3, the excitation means is a permanent magnet 4 whose magnetic field intersects the magnetostrictive lines.

Furthermore, the output signal of the excitation pulse generator O8 is applied to the magnetostrictive wire 1 via the CT.

When an excitation pulse signal flows through the magnetostrictive wire 1, an ultrasonic signal is generated within the magnetostrictive wire 1 at a position where the permanent magnet 4 is present due to the interaction between the magnetic field caused by this pulse current and the magnetic field of the permanent magnet 4.

In the example shown in FIG. 4, the excitation means is a coil 4 wound around a magnetostrictive wire 1, and a lanopulse signal is supplied from an excitation pulse generator O8 to the coil 4 via a flexible wire FW. .

In addition, as the receiving means 2, the case where a piezoelectric element is provided is shown here.

FIG. 5 is a block diagram showing the structure of an automatic balancing instrument when the device according to the present invention is applied to position feedback means.

In this device, the arithmetic circuit CK is constructed from an analog circuit.

That is, when the arithmetic circuit CK is pressed, the switch SW1 is driven by the time width signal PW1 from the flip-flop circuit FF1, and the switch SW2 is driven by the time width signal PW2 from the flip-flop circuit FF2.

An integrator INT consisting of an operational amplifier OP3 and a capacitor C1 connected to its feedback circuit is connected to a resistor RJI J
The reference voltages E and -E applied via RI2 and switches SW1 and SW2, and the output E of the arithmetic circuit CK and (output of sample hold SH) applied via resistors R21 and R2 and switches SW1 and SW2. ) and ■.

The sample hold circuit SH includes a switch SW3, a heat shield C2, and an operational amplifier OP4, which are driven by a sampling pulse SP obtained from an excitation pulse generator O8.
The output signal of the integrator INT is sampled and held in accordance with the period of the excitation pulse PE.
An analog signal Ef related to the position of the movable part 5, that is, the pointer 50 is obtained.

In this arithmetic circuit CK, in a steady state, its output signal Ef is R,=R].

=R,.

, R2=R2,=R2°, it is represented by equation (4).

A signal Ef related to the position of the pointer 50 of this arithmetic circuit CK
is compared with the signal under test Ei.

The amplifier OP5 generates a deviation signal e between the signals under measurement Ei and Ef.
Amplify the balance motor BM so that Ei=Ef,
drive

This allows the pointer 50 to follow the signal under measurement Ei.

FIG. 6 and FIG. 7 are configuration diagrams showing an example of application of the device of the present invention.

FIG. 6 shows the case where the excitation means 4 is applied to a level meter.
is connected to a float 5, which is a movable part, to detect the liquid level in the tank.

FIG. 7 shows a case where the connecting rod connecting the diaphragm 5L52 is made of a magnetostrictive wire 1, a receiving coil 2 is provided at one end of the magnetostrictive wire 1, and a receiving coil 2 is provided at the other end of the magnetostrictive wire 1. 11 is configured so that ultrasonic signals are reflected.

A small excitation means 4 is fixed to the body BO.

The diaphragms 51 and 52 have chambers 5 formed on both sides thereof.
3° 54, the magnetostrictive wire 1 and the receiving means 2 are both displaced, the distance between the excitation means 4 and the receiving means 2 is changed, and the differential pressure is detected. There is.

The configuration examples shown in Figure 6 and Figure 7 are all examples of application, and can also be applied to detect mechanical displacement corresponding to various physical quantities such as temperature and viscosity. It is.

As described above, according to the present invention, a highly accurate displacement position detection device with a simple structure can be realized.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention, and FIG.
1 is an operating waveform diagram of the device, FIGS. 3 and 4 are configuration diagrams showing other examples of excitation means used in the device of the present invention,
FIG. 5 is a block diagram showing an example of an automatic balance meter to which the device according to the present invention is applied, and FIGS. 6 and 7 are block diagrams showing examples of application of the device according to the present invention. 1... Magnetostrictive wire, 2... Receiving means, 11
... Reflection end, 4 ... Excitation means, 5 ...
...Movable part, O8...Excitation pulse generator,
OPI, OP2...comparison amplifier, FFI,
FF2...Flip-flop circuit, CK...
...Arithmetic circuit means.

Claims (1)

[Scope of Claims] 1. A magnetostrictive wire made of a magnetostrictive material and lightly supported at one end so that the propagating signal is reflected with reversed polarity, coupled to a magnetostrictive wire installed near the other end of the magnetostrictive wire. an excitation means for generating an ultrasonic signal in the magnetostrictive wire coupled to the magnetostrictive wire; ,
an excitation pulse generator that outputs an excitation pulse of 9res to the excitation means; a first flip-flop circuit that is set by the excitation pulse and reset by the positive pulse of the reception means; a first flip-flop circuit that is set by the excitation pulse; Reset by a negative pulse from the receiving means)3
the second flip-flop circuit, and the time width 1. output from the first and second flip-flop circuits. , 12
The signal of at least (tl-t2)/(t1+t
2)? , c to obtain a signal corresponding to the mechanical displacement. 2. The arithmetic circuit means uses the time width t1. which is output from the first and second flip-flop circuits. A switch driven by each signal of t2, an integrator to which reference voltages of different polarities are applied through the switch, and a circuit that samples and bolds the output of this integrator according to the period of the excitation pulse signal. and means for applying the output of the sample and hold circuit to the manual power side of the integrator via the switch.