The design of appearance of calibrating of pulse flow transducer and application

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The calibrating of coefficient of appearance of traditional pulse flow transducer is mixed by device of standard of cubage type discharge commonly tally, clock is finished, if pursue,1 is shown. Definition of its appearance coefficient measures the pulse that gives out through the sensor when flow transducer to count for the fluid of unit volume, the unit is 1L normally (pulse counts every to rise) or 1m3 (pulse counts every stere) . According to document [the regulation of 1] , to assure the effectiveness of flowmeter appearance coefficient, the opposite error absolute value that the pulse that should make sure the flowmeter in calibrating is outputted commonly figures is more than by check plural of weight by flow 13. It is ± as a result of the computation error of general tally a pulse, decide time-interval in check so (graph 1 in the time T between two control pulse) inside, tally should be collected enough the calibrating precision that much pulse counts N ability to achieve a requirement. Graph graph of demarcate of 1 appearance coefficient measures sensor to a few big runoff, because its appearance coefficient is general lesser (be like the turbine flowmeter of 200, its appearance coefficient is only 1.

5/L; The eddy street flowmeter of caliber, its appearance coefficient is lower, it is only about 0.

2/L) . To such flowmeter, should collect enough much pulse number, want to spend very long calibrating time, 2 should have larger calibrating facility (older standard vessel) . As a result of a variety of limitation, always make computation pulse short of asks. Technology of computation of double time method is current the relatively current pulse interpolation technology on international, can be inside shorter calibrating time, with the calibrating equipment of minor volume, still can assure the technology of interpolation of a kind of pulse of enough technical precision when number of computation total pulse is lesser, earlier application runs discharge standard unit at miniature bulk. We develop " appearance of calibrating of pulse flow transducer " it is to use traditional tally to add double time method to measure the calibrating of double time method that controls technical composition appearance. The experiment makes clear, this calibrating appearance is used convenient and reliable, can shorten calibrating time, with lesser standard container calibrating the flow transducer of larger requirements, and have taller technical precision than groovy calibrating method. 1, the technology is being inserted inside pulse of principle of tally of double time method is device of piston desired result the output signal resolution that increases flowmeter, reduce a of volume of desired result unit efficient way thereby. Normally, desired result discharge times to be counted to get enough pulse, can take two approaches, it is the output signal resolution that raises flowmeter, make get inside limited desired result time as far as possible much pulse number; 2 it is the metric and effective dimension that adds desired result unit. General, the pulse number that unit volume fluid exports through flowmeter place is finite (the turbine flowmeter that as above narrates and eddy street flowmeter) , the metric and effective cubage of desired result device is done impossibly also very greatly. The technology was inserted to solve this problem well inside pulse, it has law of loop of the double time method, law between the four seasons and Suo Xianghuan to wait for a few kinds of methods to be able to be offerred use. Make device of piston desired result uses " minor volume " (device is effective cubage) collect 500 pulse to be able to achieve device of large volume desired result to collect the definition with 10000 same pulse. Graph if the principle of method of double time of method of 2 pairs of time pursues 2a place is shown. In cycle of discharge pulse signal stable condition falls, number inserts to be inside pulse (1) in type: N records the pulse of flow transducer signal below to count for tally; N1 is method of classics double time or the pulse number after be being inserted inside four time methods; Δ T1 is from detect begin signal to arrive detect the time-interval of break alarm; Δ T1 is from detect ascendant edge of the first pulse after beginning signal arrives detect pulse cycle time-interval is rectified between ascendant edge of the first pulse after break alarm. Below the circumstance that accords with standard regulations regulation in stability of discharge standard device, cycle of discharge pulse signal can consider as stability, use formula so (1) number is being inserted inside gotten pulse should be effective. Besides double time method, still can decide to number is inserted inside pulse with the law between the four seasons. The law between the four seasons measures T4 of ~ of 4 time T1, if graph 2b place is shown, its pulse inserts number to be N1=N + (2) the article is appearance of calibrating of a design pulse flow transducer with double time method. 2, the hardware principle block diagram of appearance of calibrating of the hardware design pulse of calibrating appearance flow transducer is shown 3 times like the graph. Graph this calibrating appearance does not use block diagram of principle of hardware of appearance of calibrating of discharge of method of 3 pairs of time microprocessor, working dependability is good. Control signal can use single-broadsword event double cast switch K1 chooses very narrow pulse signal, also can choose n signal. When be controlled with n signal, can choose tall n control or low n control with switch K2 again. When should controlling signal to be pulse signal (graph 3 in signal of the first kind of control) , switch K1 chooses pulse control, the Q that sets TR1 of initiative condition trigger carries output to be low n L (H of hypothesis output tall n also did not concern) , end outputs tall n H to feedback to be carried to D. Switch K2 chooses tall n control or low n control. When should controlling signal to be pulse signal (graph 3 in signal of the first kind of control) , switch K1 chooses pulse control, the Q that sets TR1 of initiative condition trigger carries output to be low n L (H of hypothesis output tall n also did not concern) , end outputs tall n H to feedback to be carried to D. Switch K2 chooses tall n to control (when if the Q of TR1 of initiative condition trigger carries output,be tall n H, k2 can choose low n to control) , the D end that inputs end and trigger TR2 with what be not door B, C all is low n, so, door of B, C is shut, the Q of trigger TR2 carries output sure also below the action of discharge pulse signal for low n, e door is shut. Tally and clock T1 and T2 are suspending status. Can make with to clear pushbutton tally and clock reply initiative 0 condition, show complete 0. When " begin computation " control signal pulse (pulse of the first control) when arrival, because the D end of TR1 is tall n H, so, control pulse sparks TR1 makes its Q carries output to be tall n H, open instantly make with the B that be not the door and C tally and clock T1 begin computation and time. Have not open with the E that be not the door right now, but the D end of trigger TR2 already was tall n, the first discharge signal ascendant edge after controlling signal forward position sparks TR2, make its Q is carried output tall n and open with the E that be not the door, clock T2 also begins to time. When " stop computation " control signal pulse (pulse of the 2nd control) when arrival, TR1 is sparked again and make Q end outputs low n L, shut instantly thereby with the B that be not the door and C, make tally and clock T1 stop computation and time. But did not shut instantly with the E that be not the door, and should arrive " stop computation " the signal of the first discharge after controlling signal pulse forward position rises to spark along ability TR2 and L of output low n, shut make clock T2 stops to time with the E that be not the door. the data that gets from clock T1 and T2 era enters type (1) , attainable number is inserted inside more accurate pulse. When when control signal makes the same score signal for report (graph 3 in the 2nd, signal of 3 kinds of control) , switch K1 chooses n control, be equivalent to had crossed trigger TR1 and dominating the D end that reachs trigger TR2 with the B that be not the door and C directly so. Cent does not act well in the light of tall n or K2 of effective select switch points to low n tall n control or low n control. The movement of the others and pulse control just the same. 3, index and result 3.

Index of 1 calibrating appearance besides afore-mentioned regarding <> as outside can accusing tally and clock, this calibrating appearance still has the function that measures signal frequency and cycle. Need not time at calibrating discharge, can use as the meter that measures signal frequency or cycle alone. Specific target is as follows: ① clock, 6 LED show, resolution is 1ms; ② clock (include frequency and cycle) , 8 LED show, highest resolution is 1Hz for frequency, cycle is 0.

1 μ S, computation is ± a pulse; ③ measures range: Frequency is 10Hz ~ 100MHz, cycle is 0.

10s of ~ of 5 μ S, computation capacity is 99 999 999, clock is 1ms ~ 999.

999s; ④ T1 and T2 hand move switch to show. 3.

① of 2 tests result outputs signal of periodic square wave to serve as frequency of standard desired result and cycle to measure with 51 series microprocessor, result rank is expressed 1. Express the ② of 1 desired result result that serves as a standard with periodic square wave to produce appearance desired result with standard frequency signal, result rank is expressed 2. Express the calibrating that this calibrating appearance uses the 2 result ③ that use desired result of standard frequency signal generator at coefficient of turbine flowmeter appearance, obtained favorable result. CNC Milling CNC Machining