The utility model provides a kind of and can demarcate continuously voluntarily at the scene, can continuously, accurately measure pressure reduction again, the ultrasound wave digitizing pressure difference meter that numeral shows.
The utility model is made up of computing machine, single-chip microcomputer (comprising radiating circuit, amplification appliance, Zero crossing level testing circuit, or door, timing door, crystal oscillator markers, R0M, CPU) and new-type probe,
This new-type probe mainly is made up of two testing tubes and a standard pipe, it is the distilled water of room temperature that the interior filling of pipe has temperature, the upper end of surveying pipe is communicated with tested gas, the bottom of surveying pipe and standard pipe interconnects, a slice piezoelectric chip is respectively installed in bottom at testing tube and standard pipe, converses the water pressure difference in height of tested gas after the time difference during with the sound in the accurately known standard pipe of length with the height of fluid column in ultrasonic measurement two testing tubes.Measure sensitivity and reach 0.1 μ, in the high differential pressure measurement scope of 0-120mm measuring accuracy reach ± 0.03%.
Characteristics of the present utility model are: adopt the ultrasonic probe that is made of testing tube and standard pipe, utilize ultrasonic technique directly to measure in measuring tube because the liquid-column height that pressure reduction causes is poor, measure sensitivity and reach 0.1 μ, whole measurement is also oneself's demarcation back numeral demonstration automatically continuously, measurement result is directly perceived with chart and digital form by computing machine, accurately show also and can store, further calculate or printing the measuring accuracy height.
The utility model will be further described in conjunction with the accompanying drawings.
Fig. 1, single-chip microcomputer main body 3 are respectively with radiating circuit 4
1, 4
2, 4
2One end and Zero crossing level testing circuit 6
1, 6
2, 6
2An end connect. Radiating circuit 4
1, 4
2, 4
2The other end and amplifier 5
1, 5
2, 5
2An end and piezoelectric chip 10
1, 10
2, 10
2 Connect amplifier 5
1, 5
2, 5
3Output terminal and Zero crossing level testing circuit 6
1, 6
2, 6
3An end connect Zero crossing level testing circuit 6
1, 6
2, 6
3The other end with or door 7 be connected, timing door 8 one ends are connected with crystal oscillator markers 9, the other end is connected with single-chip microcomputer main body 3.Computing machine 2 is connected with display screen 1 with single-chip microcomputer main body 3.
The upper end of Fig. 2, survey pipe 14,17 is connected and fixed with upper mounted plate 13, and on upper mounted plate 13, air hole 11 is fixed on the middle part of cover plate 12 to cover plate 12 by screw retention.Middle fixed head 18 is enclosed within the middle part of surveying pipe 14,17, and the top of standard pipe 15 is separated measuring tube and standard pipe fixing.Upper end in standard pipe 15 is equipped with reflecting plate 16, and the hammer heart 20 is fixed on the bottom plate 21, and weight 19 is hung in upper mounted plate 13 times by hammer chain 27.Measuring tube 14,17, the lower end setting-in gluing of standard pipe 15 is on bottom plate 21 iner ledges, be equipped with a glass plate 23 in the bottom of bottom plate 21, lump together, glass plate 23 and survey pipe 14 with bottom plate 21 fluid sealants, 17, individual communication channel is arranged at the bottom that standard pipe is 15.The distance of glass plate 23 and reflecting plate 16 A Pei comparator measure of precision, error is less than 1 μ, and whole length>100mm is so precision reaches 10
-5Bottom plate 21, high-frequency socket plate 22, chassis 25 threes link fixing with bolt.In the lower surface of glass plate 23, aim at the center of surveying pipe 14,17, standard pipe 15 and be equipped with piezoelectric chip 10
1, 10
2, 10
3, piezoelectric chip 10
2, 10
2, 10
3Be connected with the high-frequency socket 24 on being fixed on high-frequency socket plate 22.On chassis 25, be provided with 3 adjustment screws 26.
Before formal the measurement, unload the air-inlet cover of two testing tubes earlier, the liquid of internal memory is all outwelled, add and room temperature the distilled water that probe temperature is identical again.Build a tight air intake opening then, tilting till whole row of gases that makes in the standard pipe 15 probe.Put positive back according to the situation of surveying water in pipe 14,17 and the standard pipe 15, in surveying pipe, pour or extract out some water again into, make the water of surveying in the pipe 14,17 roughly equal with the water in the standard pipe 15, at last another air intake opening is also covered tightly, and three adjustment screws under the adjustment chassis 26 are aimed at piezoelectric chip 10 to weight 19 with the hammer heart 20
1, 10
2, 10
3With survey pipe 14,17, the liquid level in the standard pipe 15 is parallel.Start single-chip microcomputer main body 3, the touring detection surveyed pipe 14,17, and during the sound of standard pipe 15, single-chip microcomputer main body 3 triggers radiating circuit 4 in turn
1, 4
2, 4
3To piezoelectric chip 10
1, 10
2, 10
3The emission high electric field pulse is reflected after exciting a sound wave to pass to survey liquid level in the pipe 14,17 and the reflecting plate 16 in the standard pipe 15, through amplifier 5
1, 5
2, 5
3Amplify the back by Zero crossing level testing circuit 6
1, 6
2, 6
3Detect the moment of first and second echo arrival, generation arrives the moment arrives the moment to second echo positive square wave by first echo, this positive square wave warp or door 7, pass to control gate 8, control gate 8 allows high frequency crystal oscillator markers 9 pass through during positive square wave, when the markers number that single-chip microcomputer main body 3 countings pass through records.Add a radix point through repeatedly measuring back single-chip microcomputer 3 bottom-right the 8th bit digital, the sound time difference measurement number of times of this some prompting when zero pressure difference is much of that, has also stored, proofreaies and correct as continuing, and the time difference the during zero pressure difference that contains also can upgrade.The sound time difference is 10-20ns (showing 100-200) during zero pressure difference.After when sound during zero pressure difference measure, can connect by measuring pressure and begin formal measurement, directly show to survey the water difference in height of pipe 14,17 fluid columns this moment, the time difference when the calculated altitude difference during with zero pressure difference deduct automatically and with in the accurately known standard pipe of length the time done demarcation.In real-time measuring process, single-chip microcomputer main body 3 sends the survey data to computing machine 2 incessantly and can further calculate, store according to customer requirements and show intuitively or printout on screen 1.
It is monostable 28 that the triggering emission start signal that Fig. 3 single-chip microcomputer main body 3 transmits is launched, the square wave drive emission power tube G that to produce a width be the wafer resonant frequency
1Capacitor C is passed through in conducting
1Excitation compressing tablet wafer produces a sound wave pulse, and this sound wave is propagated by liquid gas interface and reflecting plate in the fluid column of surveying pipe and standard pipe, reflects, and excites an electric signal corresponding to the echo acoustical signal again on wafer 10.Emission electric pulse and echoed signal are passed through capacitor C
2, the amplitude limit resistance R
2Pass to amplifier 5, for the very little reception echo of amplitude, limiter diode G
2, G
3Be equivalent to open circuit.For transmitting G
2, G
3Conducting guarantees the amp.in signal less than the unlikely damage of 0.7V when two terminal voltages surpass 0.7V, and the part that surpasses 0.7V is all fallen in the amplitude limit resistance R
2On.