[background technology]
Referring to Fig. 1, existing monophony ultrasonic flow meter comprises a pair of ultrasonic emitting and receiving trap 2 and the flowmeter emission/receiving circuit (figure does not show) that is arranged on outside the pipeline 1.What this monophony ultrasonic flow meter was measured is the fluid line speed on the ultrasound wave sound ray travel path in the fluid, generally can not give full expression to the velocity flow profile of whole fluid cross-section in the pipeline.Can represent the velocity flow profile of whole fluid cross-section for what make that the monophony ultrasonic flow meter records at the flow velocity of single sound channel, need the very measurement environment of high request, require mounting points that the straight length of 5D behind the preceding 10D is arranged when promptly requiring flowmeter probe to install, could guarantee that the velocity flow profile in the pipeline is more even, at this moment the linear velocity that obtains of monaural stream flowmeter measurement can be similar to the face velocity of representing fluid.
Therefore, limited the range of application of monophony flow meter for the requirement of flow development length, when flow rate of fluid distribution more complicated, the measurement representativeness of monophony flow meter will be very low, in other words, during the velocity flow profile more complicated, flow rate measurements can not be represented the mean flow rate of fluid cross-section.
For improving the accuracy of measuring, people develop a kind of phaselocked loop frequency difference ultrasonic flowmeter.This flowmeter can be referring to No. the 92201726.3rd, the Chinese utility model patent of on September 2nd, 1992 bulletin.This technology adopts continuous frequency-difference method, utilizes along the difference on the frequency of contrary two pulse sound channels and measures flow velocity and obtain the tube section flow rate mode, and it is formed along contrary two systems and difference frequency device by two.Each system then is made up of receiving transducer, receiving demodulation device, zero-crossing comparator, phaselocked loop, wave converter, modulator, power amplifier and transmitting transducer.This patent is described: it has the advantage that the fluid temperature (F.T.) of not being subjected to influences, and the precision of instrument is improved, and reaction velocity is fast.
Above-mentioned patented technology is mentioned and is utilized two pulse sound channels, yet, the actual suitable contrary both direction that is meant on the same sound travel of two pulse sound channels here, be not two complete sound channels, in fact also only energy measurement to a linear velocity of this pipeline inner fluid, still can not reflect the pipe surface rate of flow of fluid, the face velocity that the flow velocity that records can not fine representative fluid when rate of flow of fluid distribution more complicated.
[utility model content]
In order to overcome the technical matters that the prior art flowmeter can not obtain fluid surface speed when the rate of flow of fluid distribution more complicated, the utility model provides a kind of energy fine representative fluid surface speed and simple device for measuring fluxes of multi track.
The utility model solves the problems of the technologies described above the technical scheme that is adopted: a kind of device for measuring fluxes of multi track is provided, comprises at least two sound channel ultrasonic measurements, described two sound channel cross-distribution are on pipeline section.
With respect to prior art, the beneficial effect of the utility model device for measuring fluxes of multi track is: increase to measure to increase and measure sound travel, and make it the not parallel intersection angle that is, increase the representativeness of the flow velocity of other positions of pipeline section, make fluid-velocity survey be not limited to the linear velocity in this cross section, and expand to the flow velocity of other routes of cross section, improved the accuracy of measuring.
[embodiment]
Ultimate principle of the present utility model is: on the basis of monophony flow meter emission/receiving circuit, the design timesharing is measured the control circuit of sound channel flow velocity (with respect to the flow velocity of slow variation, the interval of here " timesharing " is very short, can think simultaneously), make flowmeter can timesharing obtain line mean flow rate on the different sound travels of pipeline, increase the representativeness of flow measurement, can effectively reduce the fundamental error of measurement.Make flowmeter under the situation of the flow field of fluid more complicated, also can obtain rate of flow of fluid information accurately.Increase a small amount of control circuit, can make flowmeter obtain the flow rate information source of two sound channels.
Below in conjunction with drawings and embodiments the utility model is further specified.
Consult Fig. 2 and Fig. 3, the utility model comprises emission/receiving circuit (Fig. 3) and two pairs of ultrasonic transducers 21,22.Every pair of ultrasonic transducer 21,22 comprises two emission/receiving transducers that are arranged on pipeline 10 both sides, forms a sound channel.Two pairs of ultrasonic transducers 21,22 promptly constitute the two-way sound channel, and described two sound channel cross-distribution are on pipeline 10 cross sections.In the present embodiment, described two sound channels are intersected with an angle of 90 degrees degree, are positioned at pipeline 10 same cross sections.
Described flowmeter emission/receiving circuit comprises the timesharing circuit of measurement and control of controlling described two sound channels.Described flowmeter emission/receiving circuit comprises microprocessor linked (CPU), transceiver, upstream and downstream converter, sound channel converter and ultrasonic transducer successively, described timesharing circuit of measurement and control comprises frequency divider, trigger and the driver that connects successively, described microprocessor connects frequency divider and upstream and downstream converter respectively, and described driver connects the sound channel converter.
Consult Fig. 4, X1 is the socket that connects radiating circuit/receiving circuit, and X2 is the socket that connects two sound channel converters, and X3 is the socket that receives from CPU upstream and downstream switching signal, and the direct supply that provides circuit to need.U0, U1 are the synchronous triggering decimal addition counters that can preset in the present embodiment, and it is 99 that maximum can preset number.With signal 50 frequency divisions, be about to counter and be predisposed to 49 in the present embodiment, the upstream and downstream switching signal from CPU can expire the counter meter for 50 times like this, meanwhile sends a carry signal one tunnel and gives T trigger U2, as the trigger pip of its counter-rotating; Another road feeds back to frequency counter and reloads and preset number, makes its Zhou Erfu make work.Trigger U2 is the toggle flip-flop that is formed by the J-K flip flop conversion, and frequency divider whenever sends a carry pulse, and it just reverses once.Totally two states drive switch U3, U4 by driver U5 during high level and connect a sound channel, drive switch U3, U4 by driver U5 during low level and connect another sound channel.The device that U3, U4 are made up of 4 analog switches respectively, two often open two normally closed.The electronic switch that the upstream and downstream converter also is made up of 4 analog switches, upstream and downstream switching signal from CPU, revolution changes a next state, analog switch is just connected the signal path of the transducer in upstream or downstream to receiver, and transmit is to be provided by the CPU of main circuit board control Programmable Logic Device, and it and upstream and downstream switching signal are complete synchronous.
During measurement, use the two sound channel measuring tubes 10 road inner fluid speeds of cross-distribution on pipeline 10 cross sections respectively.Can adopt the mode of timesharing measurement or synchro measure.Adopt the timesharing metering system in the present embodiment.Through the frequency divider frequency division, make toggle flip-flop change a next state from the upstream and downstream switching signal of CPU in the given time, as the sound channel switching signal of flowmeter, through driver drives sound channel converter conversion sound channel.Enter step B after having surveyed: ask mean flow rate again.
In the present embodiment, upstream and downstream switching signal from CPU, through decade counter U0, U1 frequency division, sending a pulse in per 0.5 second makes toggle flip-flop U2 change a next state, give the driver drives of forming by U5 then and change sound channel, as the sound channel switching signal of flowmeter by the channel switch that U3, U4 form.Revolution changes the signals collecting that a next state is finished a sound channel.Upstream and downstream converter and transceiver conversion ultrasonic reception and transmit direction obtain the time difference signal that contains flow information that CPU needs, and the line mean flow rate by CPU calculates two sound channels has further strengthened the representativeness of flow velocity in whole flow field.
The utility model uses the switching of frequency divider control multichannel sound passage, has increased the sampling channel of flow measurement, uses the way that increases representativeness of sample in the mathematical statistics to reduce the fundamental error of flowmeter survey, has improved the accuracy of measuring.The two sound channels design of cross-distribution on pipeline 10 cross sections is the representativeness that increases the flow velocity of other positions, pipeline 10 cross section, make fluid-velocity survey be not limited to the linear velocity in this cross section, and expand to the flow velocity of other routes of cross section, because may there be different flow velocitys in same cross section.And simple in structure, cost is low, is easy to popularize and use.When particularly Flow Field Distribution was inhomogeneous in pipeline, the measuring method of two-channel was particularly important for the accurate measurement of flow.Simultaneously its another one benefit of bringing be when flowmeter is installed straight length require corresponding reduction.
In the utility model scope, more designs can be arranged, such as will measure sound channel be increased to 3 or more than, and not parallel mutually, to increase the quantity of sampling quantity of pipe flow speed, reach more accurate purpose; The a pair of transducer of described two each sound channel of sound channel can lay respectively at the pipeline upstream and downstream, and promptly the two pairs of ultrasonic transducers 21,22 are separately positioned on the upstream and downstream of pipeline.