CN203286979U - Displacement measurement circuit - Google Patents

Abstract

The utility model discloses a displacement measurement circuit comprising a time base chip, a transformer and an operational amplifier. Excitation power supply voltage is generated by an astable multivibrator formed by the time base chip; a displacement sensor outputs alternating current voltage under the excitation power supply voltage and the alternating current voltage is in direct proportion to the displacement of an armature; alternating current output signals output by the sensor are further processed by differential rectification and phase sensitive detection circuits formed by the transformer and the operational amplifier and a filter. Through self-adaption processing of sensors, the displacement measurement circuit can match different sensors and meet the requirements for measurement on different occasions, and is suitable for various types of displacement monitoring instruments.

Description

The displacement measurement circuit

Technical field

The utility model relates to rotating machinery on-line monitoring field, is specifically related to a kind of circuit for displacement measurement, is applicable to industrial overall machine vibration monitoring protection series instrument.

Background technology

Displacement measurement is the main monitoring parameter of all kinds of big-and-middle-sized rotating machineries such as steam turbine, blower fan etc.Displacement has directly reflected the present situation of the core component of equipment, is directly connected to the safety of equipment.The situations such as there is single, less stable in existing displacement measurement mode, and the adaptive faculty of while sensor is weak.

The utility model content

The purpose of this utility model is to overcome above-mentioned weak point, and a kind of displacement measurement circuit is provided, and can mate different sensors, realizes the requirement that different occasions are measured, and is applicable to polytype displacement monitoring instrument.

The technical solution of the utility model is as follows:

a kind of displacement measurement circuit, base chip, transformer and operational amplifier while comprising, the earth terminal ground connection of time base chip, the trigger end of time base chip connects the first drop-down electric capacity, while being connected to after the first resistance and the first diodes in parallel the base chip trigger end and discharge end between, replacement keyed end and the trigger end short circuit of time base chip, between when the second resistance is connected to, the discharge end of base chip and replacement are held, replacement end, control end, the positive voltage end of time base chip connect respectively+12V voltage, an end ground connection after the second electric capacity and the second Capacitance parallel connection, the other end is connected with the positive voltage end of time base chip, an end of connection transformer primary coil after output terminal series connection the 4th electric capacity of time base chip, the other end ground connection of transformer, the 5th Capacitance parallel connection is at the two ends of transformer, the two ends of transformer secondary output coil are respectively as first input end and second input end of displacement measurement circuit, be connected in parallel on the two ends of transformer secondary output coil after the second diode, the first adjustable resistance, the 3rd diode series connection, the inverting input of concatenation operation amplifier after the 6th electric capacity that the adjustment end connection of the first adjustable resistance is drop-down and the 3rd resistance of connecting, the in-phase input end of operational amplifier connects the 4th drop-down resistance, the negative power end of operational amplifier connects the 7th drop-down electric capacity and connection-12V voltage, the positive power source terminal of operational amplifier connects the 8th drop-down electric capacity and connection+12V voltage, the output terminal of operational amplifier connects an end of the second adjustable resistance, the other end of the second adjustable resistance is connected with its adjustment end, and be connected with the operational amplifier inverting input after the 5th resistance of connecting, the output terminal of operational amplifier connects an end of the 6th resistance, the other end of the 6th resistance connects the 9th drop-down electric capacity, and as the output terminal of displacement measurement circuit.

Useful technique effect of the present utility model is:

The utility model, by the self-adaptive processing of sensor, can mate different sensors, realizes the requirement that different occasions are measured, as the measurement of the dissimilar displacement parameters such as thermal expansion, servomotor, mailbox oil level.The utility model is displacement measurement mode the most easily so far, goes for polytype displacement monitoring instrument.

The additional advantage of the utility model provides in embodiment description partly below, and part will become obviously from the following description, or by practice of the present utility model, recognize.

Description of drawings

Fig. 1 is circuit theory diagrams of the present utility model.

Fig. 2 is the oscillogram of the astable multivibrator in the utility model.

Embodiment

Below in conjunction with accompanying drawing, embodiment of the present utility model is described further.

Base chip NE555, transformer T1-B and operational amplifier LM358A when as shown in Figure 1, the utility model mainly comprises.

Earth terminal (1 pin) ground connection of time base chip NE555, trigger end (2 pin) connects drop-down capacitor C 1-B; While being connected to after resistance R 2-B and diode D1-B parallel connection between the trigger end (2 pin) and discharge end (7 pin) of base chip NE555; The replacement keyed end (6 pin) and trigger end (2 pin) short circuit of time base chip NE555; When resistance R 1-B is connected to, the discharge end (7 pin) of base chip NE555 and replacement are held between (4 pin); The replacement end (4 pin) of time base chip NE555, control end (5 pin), positive voltage end (8 pin) be connection+12V voltage respectively; An end ground connection after capacitor C 2-B and capacitor C 3-B parallel connection, the other end is connected with the positive voltage end (8 pin) of time base chip NE555; An end of connection transformer T1-B primary coil after output terminal (3 pin) the series capacitance C4-B of time base chip NE555.

The other end ground connection of transformer T1-B primary coil; Capacitor C 5-B is connected in parallel on the two ends of transformer T1-B primary coil; The two ends of transformer T1-B secondary coil are respectively as first input end ViA-B and the second input end ViB-B of the utility model displacement measurement circuit; Be connected in parallel on the two ends of transformer T1-B secondary coil after diode D2-B, adjustable resistance W1-B, diode D3-B series connection; The inverting input of concatenation operation amplifier LM358A after the capacitor C 6-B that the adjustment end connection of adjustable resistance W1-B is drop-down and resistance in series R3-B.

the in-phase input end of operational amplifier LM358A connects drop-down resistance R 4-B, the negative power end of operational amplifier LM358A connects drop-down capacitor C 7-B and connection-12V voltage, the positive power source terminal of operational amplifier LM358A connects drop-down capacitor C 8-B and connection+12V voltage, the output terminal of operational amplifier LM358A connects the end of adjustable resistance W2-B, the other end of adjustable resistance W2-B is connected with its adjustment end also and is connected with operational amplifier LM358A inverting input after resistance in series R5-B, the end of the output terminal contact resistance R6-B of operational amplifier LM358A, the other end of resistance R 6-B connects the 9th drop-down capacitor C 9-B, and as the output end vo-B of the utility model displacement measurement circuit.

Principle of work of the present utility model is as follows:

Displacement transducer (differential transformer transducer) is the meeting output AC voltage under additional excitation power supply voltage, and to the armature displacement, is directly proportional.

As shown in Figure 1, the astable multivibrator generation that formed by time base chip NE555 integrated circuit of excitation power supply voltage.The difference of stable multi-oscillation pattern and monostable pattern is that the trigger end (2 pin) of NE555 integrated circuit is connected on the capacitor C 1-B in charge and discharge loop, rather than controlled by external trigger.

After adding vdd voltage, because the upper terminal voltage of capacitor C 1-B can not be suddenlyd change, therefore the NE555 integrated circuit is in SM set mode, output terminal (3 pin) is high level " 1 ".Due at resistance R 2-B two ends and met guiding diode D1-B, so capacitor C 1-B charges to it by resistance R 1-B, diode D1-B.Trigger end (2 pin) current potential rises with the rising index of the upper terminal voltage of capacitor C 1-B, and its waveform as shown in Figure 2.

Voltage on capacitor C 1-B increases in time, and while reaching 2/3VDD threshold level (6 pin), output terminal (3 pin) is low level " 0 ".At this moment, NE555 IC interior discharge tube saturation conduction, the electric charge on capacitor C 1-B discharges through resistance R 1-B, resistance R 2-B loop.When capacitor C 2-B discharge made its voltage be down to 1/3VDD triggering level (2 pin), output terminal (3 pin) was again high level " 1 ".Above process repeats, and forms stable multi-oscillation.

Be not difficult to find out by above-mentioned analysis to the multi-harmonic-oscillations process, the duration t1 of output pulse is exactly that voltage on capacitor C 1-B is charged to the needed time of 2/3VDD from 1/3VDD, therefore the Changing Pattern of capacitor C 1-B both end voltage is:

$U_C\left(t\right)=V_{\mathrm{DD}}(1-e^{-t/R_{1-B}{C}_{1-B}})+\frac{1}{3}{V}_{\mathrm{DD}}{e}^{-t/R_{1-B}{C}_{1-B}}$

If τ is 1=R1-BC1-B, following formula is reduced to:

$U_C\left(t\right)=V_{\mathrm{DD}}(1-\frac{2}{3}{e}^{-t/{\mathrm{\τ}}_1})$

Try to achieve from following formula:

t1=-τ1ln1/2=0.6932τ1

Generally be abbreviated as:

t1=0.693R1-BC1-B

The gap phase t2 of circuit is exactly that the voltage at electric capacity two ends discharges into the required time of 1/3VDD from 2/3VDD, namely

$U_C\left(t\right)=\frac{2}{3}{V}_{\mathrm{DD}}{e}^{-t/{\mathrm{\τ}}_1}$

Try to achieve t2 from following formula, and establish τ 2=R2-BC1-B,,

t2=-τ2ln1/2=0.6932τ2

Generally be abbreviated as:

t1=0.693R2-BC1-B

T oscillation period of circuit is:

T=t1+t2=0.693（τ1+τ2）

=0.693（R1-B+R2-B）C1-B

Oscillation frequency f=1/T is namely:

f=1.443/（R1-B+R2-B）C1-B（Hz）

The dutycycle D of output waveform is:

D=t1/T=R2-B/（R1-B+R2-B）

When R2-B＞＞during R1-B, D ≈ 50%, namely exporting waveform is square wave.

, by the top derivation of equation, be not difficult to draw to draw a conclusion: (1) oscillation period and supply voltage VDD are irrelevant, and depend on the T.T. constant of charging and discharging, and be namely only relevant with the value of resistance R 1-B, resistance R 2-B and capacitor C 1-B.(2) size of the dutycycle of the wave of oscillation and capacitor C 1-B is irrelevant, and only relevant with the big or small ratio of resistance R 1-B, resistance R 2-B.

The size that can only reflect the armature displacement due to the alternating voltage of sensor output, can not reflect mobile direction, so must further by the differential rectification as shown in Fig. 1 right half part, phase-sensitive detection circuit and wave filter, to the output signal of sensor, process.

Above-described components and parts are commercial goods, and the components and parts model in embodiment can see table:

Main components table in Fig. 1:

Sequence number	The components and parts code name	The components and parts type	Component parameter or model
				1	NE555	8 pin time-base integrated circuits	?
2	T1B	Transformer	?

3

LM358A

Operational amplifier

?

Above-described is only preferred implementation of the present utility model, and the utility model is not limited to above embodiment.Be appreciated that those skilled in the art directly derive or associate under the prerequisite that does not break away from basic conception of the present utility model other improvement and variation, within all should thinking and being included in protection domain of the present utility model.

Claims (1)

1. a displacement measurement circuit, is characterized in that, base chip (NE555), transformer (T1-B) and operational amplifier (LM358A) while comprising, the earth terminal ground connection of time base chip (NE555), the trigger end of time base chip (NE555) connects drop-down the first electric capacity (C1-B), while being connected to after the first resistance (R2-B) and the first diode (D1-B) parallel connection the base chip (NE555) trigger end and discharge end between, replacement keyed end and the trigger end short circuit of time base chip (NE555), between the discharge end of the second resistance (R1-B) base chip (NE555) while being connected to and replacement end, the replacement end of time base chip (NE555), control end, the positive voltage end connects respectively+12V voltage, an end ground connection after the second electric capacity (C2-B) and the second electric capacity (C3-B) are in parallel, the other end is connected with the positive voltage end of time base chip (NE555), an end of connection transformer (T1-B) primary coil after output terminal series connection the 4th electric capacity (C4-B) of time base chip (NE555), the other end ground connection of transformer (T1-B) primary coil, the 5th electric capacity (C5-B) is connected in parallel on the two ends of transformer (T1-B) primary coil, the two ends of transformer (T1-B) secondary coil are respectively as first input end (ViA-B) and second input end (ViB-B) of displacement measurement circuit, be connected in parallel on the two ends of transformer (T1-B) secondary coil after the second diode (D2-B), the first adjustable resistance (W1-B), the 3rd diode (D3-B) series connection, the adjustment end of the first adjustable resistance (W1-B) connects drop-down the 6th electric capacity (C6-B) and the inverting input of the rear concatenation operation amplifier (LM358A) of the 3rd resistance (R3-B) of connecting, the in-phase input end of operational amplifier (LM358A) connects drop-down the 4th resistance (R4-B), the negative power end of operational amplifier (LM358A) connects drop-down the 7th electric capacity (C7-B) and connection-12V voltage, the positive power source terminal of operational amplifier (LM358A) connects drop-down the 8th electric capacity (C8-B) and connection+12V voltage, the output terminal of operational amplifier (LM358A) connects an end of the second adjustable resistance (W2-B), the other end of the second adjustable resistance (W2-B) is connected with its adjustment end, and be connected with operational amplifier (LM358A) inverting input after the 5th resistance (R5-B) of connecting, the output terminal of operational amplifier (LM358A) connects an end of the 6th resistance (R6-B), the other end of the 6th resistance (R6-B) connects drop-down the 9th electric capacity (C9-B), and as the output terminal (Vo-B) of displacement measurement circuit.

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