CN2206449Y

CN2206449Y - Extramural ultrasonic liquid level detector

Info

Publication number: CN2206449Y
Application number: CN 94216482
Authority: CN
Inventors: 马志敏
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-07-11
Filing date: 1994-07-11
Publication date: 1995-08-30
Anticipated expiration: 2004-07-11

Abstract

The utility model relates to an extramural ultrasonic liquid level detector, comprising an ultrasonic transducer (1-1) arranged on the outer wall of a container bottom or the outer wall of a by-pass bottom, a correcting reflection stop lever (1-2) which provides a standard reference reflection wave, is arranged in a container or a by-pass and is near the ultrasonic transducer, and an instrument (Y) with the functions of receiving and magnifying signal, restraining time decay, finishing, timing, processing, displaying, and warning. The utility model uses a time decay repressing amplifier, which can effectively decrease the blind area of measuring and repress the delay of transmitting and the noise of clutter. A sensing unit is arranged on the outside of a vessel wall out of touch of measured liquid medium, and is suitable for the inner liquid level measurement of sealing, containers with pressure, easy burning and explosive liquid, and corrosive liquid containers.

Description

Extramural ultrasonic liquid level detector

The utility model relates to the ultrasonic detection technology field, particularly a kind of ultrasonic liquid leveller.

Both at home and abroad about liquid Jie formula supersonic liquid level detection technique, be mainly used in the measurement of river course depth of water detection and some worn-out open container liquid levels at present, its principal feature is that sensor directly contacts the fluid to be measured medium.For airtight container with the measurement of the inner liquid level of pressure vessel is arranged, still there is not a kind of practicality at present, can directly detect the ultrasonic liquid leveller of internal tank liquid level from container outer wall.The measurement of relevant sealed container interior liquid level, mainly depend on two kinds of measuring instruments of pressure type and float-type now, the common feature of the two is the inside that sensor must be placed container, the sealing and the structural strength of container have so just been destroyed, sensor easily pollutes simultaneously, perishable, poor reliability, installation and maintenance inconvenience.

The purpose of this utility model is to provide a kind of wall outside type ultrasonic solution level detecting apparatus, realization directly detects the liquid level of internal tank from the outer wall of container, particularly solve airtight container, pressure vessel is arranged, the non-cpntact measurement of flammable and combustible liquids container, corrosive liquids internal tank liquid level, thus security, convenience, reliability and the accuracy that such tank fill level detects improved.

To achieve these goals, principle of the present utility model is to utilize hyperacoustic penetrability and reflection characteristic, by being installed in the ultrasonic transducer of container bottom outer wall or by-pass pipe bottom outer wall, launch a branch of pulse ultrasonic wave vertically upward, sound wave penetrates container outer wall, entering liquid propagates to liquid level, reflect by liquid level again, penetrate the outer wall of container, for ultrasonic transducer receives, in liquid medium, come the time of transmission back by measuring ultrasound wave, and then calculate the height of liquid level.

This wall outside type ultrasonic solution level detecting apparatus, comprise a ultrasonic transducer that is installed in container bottom outer wall or by-pass pipe bottom outer wall, one at internal tank or the inner correction reflection pin that a canonical reference reflection wave can be provided near ultrasonic transducer of by-pass pipe, a reception that comprises signal is amplified, the time decay suppresses, arrangement, during survey, computing, show, the instrument of warning function.

In order to reduce to measure the blind area effectively, time decay rejective amplifier has been adopted in the hangover that inhibition transmits and the interference of clutter in this device.In the emission ultrasonic signal, produce the reference voltage of the voltage of an index variation in time as detection output, when the output of amplifying circuit is higher than (when the positive level detection is exported) or is lower than (when the negative level detection is exported) this reference voltage, signal can pass through, otherwise signal is suppressed, suppress level in time by the exponential relationship decay, inhibiting effect is by dying down by force, realization has very strong inhibition to signal closely, weaken and increase inhibiting effect far away, to the basic unrestraint of distant signal with distance.

This device is close ultrasonic transducer place in internal tank or by-pass pipe, one standard reflection pin is set, and the ultrasound wave sub-fraction that transducer is sent is reflected by pin, and another part then continues to propagate, behind liquid level, reflect again, measure the travel-time t of pin reflection then respectively ₀With the travel-time t of liquid level echo, establishing pin length is L ₀, liquid level is L, just can have been asked the height L=L of liquid level by following formula ₀T/t ₀Eliminated temperature, pressure so effectively, the influence of factors such as composition, thus having guaranteed higher measuring accuracy, instrument has extensive adaptability to the liquid medium acoustic-velocity characteristic.Need not be concerned about the speed that ultrasound wave is propagated when measuring like this in concrete object.

The concrete structure of the present utility model and the course of work are provided by following embodiment and accompanying drawing.

Fig. 1 is the installation diagrammatic sketch of this wall outside type ultrasound wave liquid level pick-up unit.

Fig. 2 is this wall outside type ultrasonic solution level detecting apparatus composition frame chart.

Fig. 3 a, 3b, 3c, 3d are the time decay rejective amplifier wiring diagrams in this wall outside type ultrasonic solution level detecting apparatus.

Follow by-pass pipe 14 on the next door of container 15 among Fig. 1, adorning ultrasonic transducer 1-1 vertically upward in by-pass pipe 14 bottom outer wall, adorning a correction reflection pin 1-2 that a canonical reference reflection wave can be provided at by-pass pipe 14 inner close ultrasonic transducers (1-1), in order to revise of the influence of factors such as fluid temperature, pressure and composition to ultrasonic propagation velocity.The detection signal of ultrasonic transducer 1-1 be input to one have that signal reception, amplification, time decay suppress, arrangement, when surveying, the instrument Y of computing, demonstration and warning function.

In the composition frame chart of this ultrasonic solution level detecting apparatus (Fig. 2), 1 is ultrasonic transducer (1-1) and correction pin (1-2), 2 preposition emission amplifiers, 3 synchronizing circuits, 4 receive amplifying circuit, and the decay of 5 times suppresses circuit, 6 signal conditioning circuits, 7 timekeeping circuits, 8 one-chip computer circuit, 9 digital display circuits, 10 parameter setting circuits, 11 sound light alarming circuits, 12 serial ports output circuits, 13 current signal output circuits, each circuit system of sequence number 3-13 is contained among the instrument Y.

The course of work of this device is under the control of synchronizing signal, preposition emission amplifier 2 produces a high-voltage pulse signal, excitation ultrasonic transducer 1-1, make it vibration, launch a branch of high-frequency impulse ultrasound wave, the outer wall that ultrasound wave passes container enters liquid, reflect by liquid level again, for transducer receives, fore-lying device amplifies the feeble signal of liquid level echo, passes to instrument by cable, through photoelectricity every after enter the amplifying circuit 4 of instrument, the time decay suppresses circuit 5 provides an inhibition level that changes by exponential damping in time, reduces to measure the blind area and eliminates the purpose of disturbing in order to suppress the hangover and the noise of transmitted wave, to reach.Signal after suppressing amplifies again, pass to signal conditioning circuit 6 then echoed signal is made into square wave, select to carry out timing to proofreading and correct echoed signal and liquid level echoed signal respectively by one-chip computer control again, timing circuit 7 detects the corresponding time, pass to single-chip microcomputer 8 again, carry out computing and Filtering Processing, draw corresponding level value, show by digital display circuit 9, one-chip computer is also according to detected current level value with by in parameter setting circuit 10 settings, the differentiation of transfiniting of bottom limit level value, if liquid level transfinites, then carry out sound and light alarm by sound light alarming circuit 11.This device current signal output circuit 13 also provides standard 4-20mA analog current signal output and standard Rs-232C serial communication interface 12, thus realize signal teletransmission and with the information transmission of high-order computer system.

Fig. 3 is a specially designed time decay rejective amplifier example in the utility model, and Fig. 3 a, 3b, 3c, 3d show four kinds of modes of connection.In Fig. 3 a and 3b, diode D ₁Negative pole is connected to pre-amplifier A ₁Output terminal, positive pole is received the B point.One end of capacitor C links to each other with the output terminal of synchronizing signal T, the other end and variable resistor Rw ₁Receive triode BG after the serial connection again ₁Base stage.Triode BG among Fig. 3 a ₁Emitter be connected to negative supply E _-, BG ₁Collector be connected to the B point.Triode BG among Fig. 3 b ₁Emitter be connected to the B point, collector is connected to E _-, resistance R ₁One terminates to positive supply E ₊, the other end and adjustable resistance Rw ₂Polyphone, adjustable resistance Rw ₂The other end receive B point, R ₂One terminates to E _-, the other end is received the B point, and the signal after the inhibition is delivered to post-amplifier A from the output of B point ₂Input end.

In Fig. 3 c and 3d, diode D ₁Positive pole receive pre-amplifier A ₁Output terminal, negative pole be connected to the B point.Triode BG among Fig. 3 c ₁Collector receive positive supply E ₊, emitter is connected to B.Among Fig. 3 d, triode BG ₁The utmost point of sending out receive power supply E ₊, collector is connected to B point, all the other resistance R ₁, R ₂, Rw ₁, Rw ₂With being connected of capacitor C with described in Fig. 3 a, the 3b.

In Fig. 3 a, 3b, diode D ₁As amplifier A ₁The wave detector of output signal, it allows amplifier A ₁Output signal is lower than the part of B point voltage to be passed through, and is higher than B point voltage part and then is suppressed adjustable resistance Rw ₁, capacitor C and triode BG ₁Be used for producing the voltage that a drop-down exponential damping changes, adjustable resistance Rw at the B point ₁Determined the time constant of index curve with capacitor C.The course of work of this circuit is when synchronizing signal arrives, and promptly launches hyperacoustic moment, and synchronizing signal is by adjustable resistance Rw ₁With triode BG ₁To capacitor C charging, initial time triode BG ₁Saturation conduction, B point voltage V _BNear E _-, along with the voltage increases of capacitor C, charging stream reduces V by exponential relationship _BAlso increase by exponential relationship gradually, until the time of 5 times time constants, V _BSubstantially be returned to steady-state value, obtain a negative inhibition level at the B point like this, realized stronger inhibition of emission hangover signal and the inhibition more weak, thereby reduced the measurement blind area the liquid level echoed signal by exponential relationship decay.

In Fig. 3 c and 3d, diode D ₁Be connected into forward conduction, promptly allow amplifier A ₁Output signal voltage is higher than the part of B point voltage to be passed through, and the part that signal voltage is lower than the B point voltage then is suppressed, triode BG ₁Received E ₊With the B point, at synchronizing signal T and capacitor C, adjustable resistance Rw ₁, triode BG ₁Acting in conjunction under, the exponential damping voltage that draws on the B point produces one is as detector diode D ₁Reference voltage, thereby finish transmitted wave hangover signal is suppressed more by force and to the more weak inhibition of liquid level echoed signal or do not suppress, reaches the purpose that reduces to measure the blind area.

R among Fig. 3 ₁, Rw ₂And R ₂, power supply E ₊, E _-Constitute the steady state partial pressure circuit that B is ordered, adjust Rw ₂Can change stable state and suppress level, eliminate noise.

During actual the use, can adjust Rw according to concrete object ₂, promptly change the time constant that suppresses curve, make the attenuation characteristic that suppresses curve approaching or consistent, thereby obtain to suppress preferably effect with the acoustic pressure attenuation characteristic of liquid.

Characteristics of the present utility model are that ultrasonic sensor need only be installed in outside the chamber wall, do not contact the fluid to be measured medium, thereby have structural strength and a sealing of not destroying container, do not have with fluid to be measured and to electrically contact, safety anti-explosive does not have corrosion, good reliability, be particularly suitable for airtight container, pressure vessel, flammable and combustible liquids container arranged, the level gauging of corrosive liquids internal tank.

Claims

1, a kind of wall outside type supersonic liquid level checking device, it is characterized in that it comprises a ultrasonic transducer (1-1) that is installed in container bottom outer wall or by-pass pipe bottom outer wall, one inner near ultrasonic transducer (1-1) at internal tank or by-pass pipe, the correction reflection pin (1-2) of a canonical reference reflection wave can be provided, one has signal and receive to amplify, the time decay suppresses, arrangement, when surveying, the instrument (Y) of computing, demonstration and warning function.

2, wall outside type ultrasonic solution level detecting apparatus as claimed in claim 1 is characterized in that the time decay among the instrument Y suppresses circuit (5) by diode D ₁, resistance R ₁, R ₂, adjustable resistance Rw ₁, Rw ₂, capacitor C, transistor BG ₁Or constitute diode D with device that transistor has a same function ₁Negative pole is received pre-amplifier A ₁Output terminal, positive pole is received the B point, an end of capacitor C links to each other with the output terminal of synchronizing signal T, the other end and variable resistor Rw ₁Receive triode BG after the serial connection again ₁Base stage, triode BG ₁Emitter be connected to negative supply E _-, collector is connected to B point, perhaps triode BG ₁Emitter be connected to the B point, collector meets negative supply E _-, resistance R 1 one termination positive supply E ₊, the other end and adjustable resistance Rw ₂Polyphone, adjustable resistance Rw ₂The other end receive B point, R ₂One terminates to E _-, the other end is received the B point, and the signal after the inhibition is delivered to post-amplifier A from the output of B point ₂Input end.

3, wall outside type ultrasonic solution level detecting apparatus as claimed in claim 1 is characterized in that the time decay among the instrument Y suppresses electricity (5) by diode D ₁, resistance R ₁, R ₂, adjustable resistance Rw ₁, Rw ₂, capacitor C, transistor BG ₁Or constitute diode D with device that transistor has a same function ₁Positive pole receive pre-amplifier A ₂Output terminal, negative pole is connected to B point, triode BG ₁Collector receive positive supply E ₊, emitter is connected to B point, perhaps triode BG ₁Emitter receive positive supply E ₊Collector is connected to the B point, and an end of capacitor C links to each other with the output terminal of synchronizing signal T, the other end and variable resistor Rw ₁Receive triode BG after the serial connection again ₁Base stage, resistance R ₁One terminates to positive supply E ₊, the other end and adjustable resistance Rw ₂Polyphone, adjustable resistance Rw ₂The other end receive B point, R ₂One terminates to E _-, the other end is received the B point, the amplifier A after the signal after the inhibition is delivered to from the output of B point ₂Input end.