CN101424695A - Rotate speed and differential measurement method without velocity metre - Google Patents

Abstract

The invention relates to a method for measuring rotary and differential speed without a velocity metre, which is characterized in that signals collected by sensors on a rotary drum and a rotor are directly input into a Rockwell MicroLogix1500 PLC processor provided with high-speed counters and then are output into a touch display screen by the PLC processor provided with the two high-speed counters of HSC0 and HSC1; and an impulse method is used for measuring the rotary speed of a high-speed section, and a periodic method is used for measuring the rotary speed of a low-speed section. As the PLC processor provided with the high-speed counters replaces the velocity metre and has the function of speed measurement of the velocity metre, the PLC processor is in charge of the routine control of a system, the potentiality of the PLC processor is fully tapped, and the PLC processor also has the function of speed measurement. The strong programming instruction, the timer interruption call function and the high programming flexibility of PLC are utilized, the impulse method which controls the high-speed section and the periodic method which controls the low-speed section are respectively used for measuring the speed, and the high-speed and the low-speed sections can have favorable accuracy of speed measurement and stability.

Description

A kind of rotating speed and differential measurement method that does not have velocity metre

Technical field

The present invention relates to a kind of measuring method of counter, particularly a kind of method of carrying out the measurement of rotating speed and differential simultaneously.

Background technology

Two coaxial rotations in the same way of rotary body are being arranged, and the occasion of mutual close association is being arranged, usually needing to measure the rotating speed of one of them rotary body, measuring the speed discrepancy (hereinafter to be referred as differential) between these two rotary bodies simultaneously again.

For example, the hydro-extractor that is widely used in the sewage disposal system just needs to measure the rotating speed of its rotary drum, and the differential between rotary drum and the rotor.(see figure 4)

What Fig. 4 provided is the exemplary that this class tests the speed.PLC mainly is responsible for the control of total system, wherein will use rotating speed and differential.In the measuring point of rotary drum and rotor, be evenly distributed with 3 grooves by circumference, the sensor that whenever rotates a circle can measure 3 pulses, and velocity metre calculates real-time rotating speed and differential according to the pulse that sensor records, and shows on nixie display.Simultaneously, velocity metre carries out the D/A conversion to rotating speed and differential, transmits rotating speed and differential signal in the mode of analog quantity to PLC, by the A/D module analog quantity is converted to digital quantity again in PLC, and screen displaying goes out rotating speed and differential then.

Be not difficult to find to use in this system existing velocity metre, velocity metre is except showing rotating speed and differential, and footpath PLC also shows on touch-screen through the conversion back.This has just produced a problem, that be exactly on the velocity metre on data presented and the touch-screen data presented all the time to not holding together, its reason just be first D/A in the transmission course again the A/D conversion cause, because, the data revolution changes a precision and will descend once, add the drift that analog quantity is difficult to overcome, or the like, finally caused two video datas to not holding together.

Also have a deadly defect in addition, by the pulse measuring principle as can be known, the umber of pulse that measures in the unit interval is many more, and rate accuracy is just high more.In other words this velocity metre is suitable for high regime to be used, for example 2000 rev/mins or higher, tens just powerless for having only to the low speed of hundreds of rev/min, low speed segment can factor according to acutely beating and can't using.

Summary of the invention

Purpose of the present invention: be intended to propose a kind of the do not have rotating speed of velocity metre and the method that differential is measured, both overcome on the velocity metre on the data presented and touch-screen the data presented defective to not holding together all the time, and also can make it be applicable to tens the detections that slowly run simultaneously to hundreds of rev/min.

This method of carrying out the measurement of rotating speed and differential simultaneously, it is characterized in that: will be separately positioned on the signal that sensor 3-1 on rotary drum 1 and the rotor 2 and sensor 3-2 are gathered, directly input has the PLC processor 4-1 of high-speed counter, then exports touch display screen 5 to through this PLC again.

Described PLC processor is the MicroLogix1500 processor that carries the Rockwell of No. two high-speed counter HSC0 and HSC1.

Adopt impulse method to measure the rotating speed of high regime, measure the rotating speed of low speed segment with periodic method.

This method of carrying out the measurement of rotating speed and differential simultaneously according to above technical scheme proposition, owing to adopt the PLC processor of band high-speed counter to substitute velocity metre, the speed measuring function of velocity metre is merged to PLC, make this PLC except the routine control of being responsible for system, fully excavate its potential, also bear speed measuring function.Utilize the powerful programming instruction of PLC, timing interrupt call function, and the programming dirigibility of height, (being in charge of low speed segment) segmentation control that the employing impulse method tests the speed (being in charge of high regime) and periodic method tests the speed makes high regime and low speed segment that good rate accuracy and stability all be arranged.This paper proposes a kind of method of getting rid of velocity metre, can thoroughly solve above-mentioned drawback, and circuit is also simple simultaneously.

Description of drawings

Accompanying drawing 1 is a speed-measuring method process synoptic diagram of the present invention;

The different pulse number synoptic diagram of accompanying drawing 2 in identical sampling period T, measuring;

Accompanying drawing 3 is the periodic method that the adopts 8 frequency divisions synoptic diagram that tests the speed;

Accompanying drawing 4 is traditional speed-measuring method process synoptic diagram

Embodiment

The rotating speed of this no velocity metre as shown in Figure 1 and differential measurement method, it is a kind of inventive improvements to existing congenerous method of testing.

The rotating speed of this no velocity metre and differential measurement method, it is characterized in that: will be separately positioned on the signal that sensor 3-1 on rotary drum 1 and the rotor 2 and sensor 3-2 are gathered, directly input has the PLC processor 4-1 of high-speed counter, then exports touch display screen 5 to through this PLC again.

Described PLC processor is the MicroLogix1500 processor that carries the Rockwell of No. two high-speed counter HSC0 and HSC1.

Adopt the rotating speed of impulse method test high regime, with the rotating speed of periodic method test low speed segment.

Speed-measuring method and principles illustrated that the present invention proposes are as follows:

The PLC of brand commonly used has high speed counting module optional on the market, if select the MicroLogix1500 of Rockwell for use, just carries No. two high-speed counters (HSC0 and HSC1) on its basic module, just can be used for measuring two road rotating speeds.

Speed-measuring method is divided into impulse method and periodic method.So-called impulse method is exactly to calculate rotating speed with the umber of pulse that measures in the unit interval, calculates two road rotating speeds earlier, calculates differential again; And so-called periodic method is the time interval of measuring between adjacent two pulses, i.e. in the cycle, go out rotating speed according to computation of Period then, in like manner, has known two road rotating speeds, can calculate differential.

The high-speed counter of PLC is a kind of counter of hardware based software-controllable, and it both had been independent of CPU operation, had satisfied real-time, can allow program read wherein data and control at any time again, and this characteristic has satisfied the pacing items that numeral tests the speed.Utilize PLC adjustable timing interrupt function flexibly again, just can adjust the time of regularly interrupting easily, to adapt to the application of impulse method and periodic method.

1. impulse method

Figure three is illustrated in the fixing sampling period T, because the different different situations of umber of pulse of being adopted of the height of rotating speed.Know the umber of pulse f that adopts in the unit interval T, just known rotating speed.

Because 1 commentaries on classics represent in per 3 pulses, if T is chosen as 1s, rotating speed formula then:

$n=\frac{60f}{3}=20f$ ... .... (sampling period T=1s)

Unit: n-r/min wherein, f-1/s.

2. periodic method

Is the key of periodic method the time interval (cycle) of measuring between two adjacent pulses, how the measurement of performance period? this method is to utilize the timing interrupt function of PLC to realize.For the MicroLogix1500 series of PLC, regularly interrupting minimum time can be set at 1ms, that is to say that every 1ms just produces interrupt call 1 time, carry out 1 sub-subroutine, in subroutine, arrange a counter, whenever call 1 time, counter adds up once, rising edge control counter by first tacho-pulse begins counting simultaneously, and the numerical value and the zero clearing of reading counter at the rising edge of next tacho-pulse, counter go round and begin again be counted, read, zero clearing.Because the interrupt call time interval is 1ms, the value that finally is read in counter is exactly two time intervals between adjacent pulse, i.e. cycles.Suppose that the counter maximal value is 100, the cycle of being surveyed with regard to expression is 100ms.The cycle rotating speed of just being not difficult to calculate has been arranged, and then calculated differential.

Is here also having a problem, exactly that what if not low rotating speed is not high? speed is when interlude in fact, no matter be impulse method or periodic method, the way that can suitably reduce the sensitivity of testing the speed improves rate accuracy.Very simple for impulse method, just can improve rate accuracy as long as suitably strengthen the sampling period, repeat no more here; Can be with the frequency division method Measuring Time (see figure 3) that extends for periodic method.

Here in order to measure abundant time main pulse, can be to tacho-pulse frequency division (this example be 8 frequency divisions), purpose is to elongate Measuring Time, so that there is more pulse to go on record.Obtaining removing 4 behind the umber of pulse P, is that the time main pulse between adjacent pulse is counted P ', because time base period is 1ms, so umber of pulse is exactly the ms number.The speed calculation formula is:

$n=\frac{60\×{10}^3}{3P\′}=\frac{2\×{10}^4}{P\′}.........(r/\min )$

3. the switching point of impulse method and periodic method

This problem is fairly simple, try to achieve switching point, as long as the computing formula simultaneous of above two kinds of velocimetries, because at this time two kinds of velocimetry rotating speeds are equal with umber of pulse, and the speed n in the time of just can be in the hope of switching point _Cut, repeat no more equally here.

Claims (3)

1, a kind of rotating speed and differential measurement method that does not have velocity metre, it is characterized in that: will be separately positioned on the signal that sensor (3-1) on rotary drum (1) and the rotor (2) and sensor (3-2) are gathered, directly input has the PLC processor (4-1) of high-speed counter, then exports touch display screen (5) to through this PLC again.

2, a kind of rotating speed and differential measurement method that does not have velocity metre as claimed in claim 1, it is characterized in that: described PLC processor is the MicroLogix1500 processor that carries the Rockwell of No. two high-speed counter HSC0 and HSC1.

3, a kind of rotating speed and differential measurement method that does not have velocity metre as claimed in claim 1 is characterized in that: adopt impulse method to measure the rotating speed of high regime, measure the rotating speed of low speed segment with periodic method.

Images