Engine checks the rotate speed in the system to measure

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In industrial production and experiment process, be measured via what regular meeting encounters all sorts of rotate speed and control a problem. The method can wait through electromagnetism or photoelectricity below most circumstance, measure rotate speed change for frequency. The method that measures frequency has a lot of, different method has different suitable scope each. In recent years the rapid development as electronic technology, industry is measured accuse equipment to be updated ceaselessly, the method that frequency measures and equipment also have new progress. In applying actually, choose different technique to devise plan, the effect may differ very far. The article is measured with the rotate speed in system of test of engine test bed for exemple, if the specification can be specific analysis, suit the remedy to the case, devise plan and design work has done specific technology fine, use simple method, mining to already had measure the latent capacity that controls device, also can obtain satisfactory result. General situation of 1 test system and the bed of requirement engine test that measure to rotate speed test a system is to solve the problem of experiment leaving a line of train (undertake engine is safeguarded and all need to have a test when routine test) and of the design. Before this kind of experiment is to use the thrust deep into the enemy forces inside the online means, free space in train line road to undertake, become more difficult, train is carried fast hind, line is more taut. Want to solve this one problem thoroughly, be necessary to build the test bed that leaves a line to test a system, undertake to engine the line checks leaving. The structure of test system is shown 1 times like the graph. Wait for try engine to be arrived to experiment by drive on the bed, engine wheel is ordinal with transmission annulus rub close. Transmission annulus is ternary, pass mechanical synchronism first, part next drive two dynamometer () of excitation generation set. The output of dynamometer receives the water resistance array that size can control to go up, imitate engine is laden, consume engine power. When the experiment, engine is started below certain condition, adjust the load of dynamometer and rotate speed, can make engine according to with the similar operating mode on circuit (traversal speed and pull motive force) move. Allow when to be engraved in the experiment, the rotate speed of two dynamometer must keep consistent. With ordinary control object photograph is compared, to the rotate speed of dynamometer control asks rate is rapidder, after joining core electric current to feedback especially; Taller also to the indication precision requirement of rotate speed, when the hope is measuring rotate speed upper limit, opposite error is more than 0.

2 % . Annulus adjustment cycle is the electric current that designs in this system O.

1 second, use at the rotate speed that show and records to measure cycle to be 1 second, the rotate speed that test system designs measures limits to be 200 ~ 1000 turn / cent. The rotate speed of dynamometer measures performance to whole system run the action with a decisive move. The control that needs to fall in the car in the experiment additionally is indoor the important parameter that goes up to engine undertakes monitoring, include the rotate speed of electric current of the voltage of the dynamo on the car, electromotor and diesel engine. To diesel engine rotate speed, the electric pulse signal that every turn is provided only normally on the car, rotate speed limits is 500 ~ 1500 turn / cent. Because these measure parameter to just be used at running condition to undertake monitoring to engine, because this pair gauges precision and the demand that measure speed not tall, the ~ of L of opposite sum of errors that is not more than 1 % of 3 seconds measure cycle can. The measurement that considers pair of dynamometer and control speed demand are reached higher rise measure the interference rejection ability that controls a system, controller of the CJ1-M that test system uses OMRON PLC serves as leave an opportunity, executive majority is measured and control the job; The data on engine passes the data on the portable car that with Adam-4017+ quantity of 8 passageways imitate inputs module to be formed for core to collect device to undertake collection, bus line of collection result classics RS-485 conveys to go up a monitoring machine. The article discusses the rotate speed of dynamometer and diesel engine to measure an issue only. The rotate speed in system of 2 engine test is measured 2.

The rotate speed of 1 dynamometer is measured there can is a special unit in series of CJl of process designing controller is CT021 of unit of high speed computation. Every CT021 has tally of two high speed, the capacity of every tally is a binary system 32, acceptability frequency is as high as the input pulse of 50kHz, in order to realize the accurate control of rapid movement. Two rotate speed that input a passageway to be used at two dynamometer respectively are measured. CT021 uses counting method to measure the frequency that inputs signal. Choose resolution to realize rotate speed for the photoelectricity coder of 1024 changeover of frequency of one telecommunication size. In rotate speed floor level (200 turn / cent) when, the pulse frequency that outputs actually is 1024 × S of 200 / 60s=3400 / , namely 3400Hz. It is O to realize cycle.

Adjust of 1 second quickly, should deserve to be with cycle 0.

The high speed sampling of 1 second, right now every cycle can collect pulse to be 340, opposite error does not exceed ± O.

3 % , OK and contented rotate speed controls a demand. When rotate speed upper limit. The measurement of counting method precision can have improvement, but need to check computation unit is restricted to inputting the upper limit of pulse frequency. Rotate speed is 1000 turn when the portion, input pulse frequency is 1024 × 1000 / 60s, namely 17.

07kHz, won't exceed the limitation of upper limit of frequency of 50kHz hardware pulse. Although afore-mentioned single-phase pulse input means to be able to have satisfied a system to measure fast requirement, it is the surplus with retain certain, the system uses poor photograph actually to input means, make the frequency that inputs pulse raises one times, measure an error to reduce an in part again. Finish afore-mentioned checking the job, affirmatory after measuring place to need hardware, the work that should do on software is opposite simpler, the technical data that should provide according to manufacturer only is right in the program the working way of CT021 undertakes correctly initialization is installed, the program after electrify can circulate in every in the memory address that computation result deposits the lieutenant general to appoint. Can shift these data data memery block, use for implementing the directive of rotate speed adjustment. CT021 still provides a variety of functions, can realize two-way computation for example, have two control input and two control output and 30 soft output to wait, can configure neatly to them, use the special requirement that the spot may appear in order to satisfy. Be worth what carry is, one of functions that CT021 provides are OK automatic will successive a certain number of second (highest can amount to 64 words) rate measures result record to be in the memery block with a successive address, and at any time automatic refresh, can be in every already so 0.

1 second gets the sampling value at that time dictates for adjusting inside total cycle time use, also can get easy to doly many more successive periodic total count result, namely longer the sampling value inside time-interval, offer what show and record to use. Sampling time expanded, quantify an error to be reduced accordingly, better land satisfied the requirement to showing precision. 2.

The diesel engine rotate speed that the diesel engine rotate speed on 2 engine measures engine to go up turns for 500~1500 / cent, the frequency of the pulse that be measured is 500 / 60s(8 only.

3Hz)~1500 / 60s(25Hz) , use counting method to undertake frequency is measured apparent improper. Because not be very tall to gauging the demand of precision, can use imitate method. Graph 2(a) place is shown is a circuit that use LM2917 undertakes imitate type is measured to diesel engine rotate speed. LM2917 is one use technically at rotate speed to measure with frequency of pilot integrated circuit one voltage changes chip. The principle of pump of charge of its according to works, compare with photograph of common charge pump circuit, this chip is compositive the comparator input class that has float input and the output class that can have be designinged again neatly, amount of yuan of parts of an apparatus that outside reducing the need when chip throws application greatly consequently, receives. The input float character that inputs class makes the user can adjust the threshold value that signal inputs, increase the interference rejection capacity of circuit; In its interior returned compose to build a twinkling to spend the sluggish annulus that is 15mV, can raise circuit further thereby fight noise to disturb ability. The output level of chip is comprised by comparator and dynatron of a float, the user can design more relative than J of an ancient measure of length equal to seven or eight chi is outputted or be restricted to be worth output, output form can be voltage or electric current, in order to satisfy different control requirement. Graph 2(a) place shows circuit to offer scale voltage output. The capacitance C1 in the graph is charge pump charge capacitance, c2 is integral capacitance. The place in pressing a plan chooses parameter, the commutation relation between input pulse and output voltage is: Graph 2(b) shows the test result of circuit for graph 2(a) place. In the graph, lower curve is the outcome that F/V changes, the collection that the curve of upside reachs follow-up Adam-4017+ module to included linear photoelectricity isolator data. Besides afore-mentioned imitate type methods, also tried to dig the latent capacity of FLC controller, use Dl input, according to wait for precision method to undertake metrical to diesel engine rotate speed. Use timer comes true beforehand the width control of sampling window, with timer of 1ms high speed appropriative and high frequency reference quantifies pulse. The graph shows the software flow that measures a process to come true and undee sketch map 3 times. In the graph, t1 is the timer that sets sampling window width beforehand certainly, t2 is Hns timer, smp is sampling mark, n is computation of the pulse that be measured to be worth. Read an ascendant edge that inputs pulse every time, CPU inquires sampling indicates above all, if be O, criterion buy 1, start sampling process. Of sampling process book width to be decided by timer Tl. Tl is time when arriving, do two things: On one hand, 1ms timer has time count continuously; On the other hand, PLC is right input pulse computation (N=N+1) , new pulse is encountered to rise after till Tl is time,arriving till the edge. When ending like sampling, the value of Ms accumulative total that reachs from Lms timer is N, the computation value that inputs pulse is Ⅳ , can get signal frequency to be: Because PLC is in,the ability after the program circulates has I/0 break centrally, accomplish sampling window and synchronism of the pulse that be measured very hard accordingly. To reduce the effect that this one element brings as far as possible, took two step: (1) jumps to what pulse inputs signal change use instantly refresh means undertakes detecting. (2) is in whole PLC program, dispersive ground is inserted more than test point of an input pulse. The experiment proves, these measure are effective, should measure plan to also can satisfy experiment requirement, and hardware cost is very low (a DI that uses PLC only inputs) . Of course, if use,discontinue unit, by suspend means work, the initiative time of sampling window and the synchronous meeting of the pulse that be measured become very simple, accuracy also can rise, cost is hardware cost raises. In system of engine fixation test, gauge demand to what differ, concrete analysis, distinction is treated, took different frequency measurement technique and facility, specific aim ground was adopted reduce the handle that measures an error, as far as possible mining already had measure the latent capacity that controls device, do good technology to design the job. These effort already got field test proves, the result is satisfactory. CNC Milling CNC Machining