SU1677639A1 - Rotational speed extreme values indicator - Google Patents

Abstract

The invention relates to an instrumentation technique and can be used in automatic control and monitoring systems in which information is presented in a particular form. The purpose of the invention is to increase the reliability of the device when it controls the frequency out of the operating range by increasing noise immunity. The indicator monitors the rotational speed of the engine in such a way that when the rotational frequency goes out of the working range, the indicator generates a command to lower or increase the frequency from the nominal one. On waken, the command is generated only by eating the receipt of a p-fold confirmation of the frequency change in the operating mode. When the indicator is turned on in the monitoring mode, it also requires n-fold confirmation of the nominal mode of the engine, which allows to avoid accidental noise on the frequency sensor circuit, increase the noise immunity of the indicator, and hence its reliability, 1 Cpfl, 7 ill., 1 tab.

Description

The invention relates to a measuring and control technique and can be used in automatic control and monitoring systems in which information is presented in frequency form.

The purpose of the invention is to increase reliability.

FIG. 1 is a block diagram i of the rotational speed limiter; in fig. 2 - frequency range of operation of the object under study; in fig. 3 shows timing charts for various occurrences of interference; in fig. 4 - time diagrams of the sensor signals when one and two information pulses disappear; in fig. 5 - time diagrams of the device; in fig. 6 is a circuit diagram of a control unit;

Fig. 7 is a schematic diagram of the initial installation block.

The indicator includes a rotation speed sensor 1, a shaper 2 input signals, a control block 3, a generator of the reference frequency generator, counter 5, a block of the initial setup, a decoder 7, the first-third D-flip-flops 8-10, the first third elements OR 11-13, first to sixth elements AND 14-19, first to third threshold accumulators 20-22, fourth element OR 23, fourth D-flip-flop 24, driver 25 output commands, consisting of the seventh element AND 26 and eighth element AND 27 and p of element OR 28.

The alarm limit values of the rotational speed works as follows.

DS VJ

Os

SLE

After supplying the supply voltage device, a potential corresponding to 1 appears at the input of the initial installation unit 6, and the unit 6 generates a single pulse, which brings the accumulator 21 to zero and sets the trigger 24 to its initial state, in which from the output of this trigger to the second the input of the driver 25 a prohibitory signal is given.

With the arrival of the signal Ci (Fig. 5) from the sensor 1, corresponding to the end of Ti and the beginning of Ti of the monitored period, the generator 2 is triggered, which generates a pulse enabling operation of the control unit 3. At the same time, a pulse appears at the first output of block 3, which is fed to the first input of counter 5 and prohibits the arrival of the GOCH signals 4 to counter 5, and thus ends the conversion process of the period Ti and the Mi code.

After a time interval G |, the value of which should be longer than the duration of transients in counter 5, a pulse appears at the second output of control unit 3. This pulse is applied to the first inputs of the elements A 14-19 and the device ends monitoring the number obtained by converting the period Ti to the Mi code.

After the end of the pulse, a pulse appears at the third output of control unit 3 at the third output of this unit and the inhibiting pulse ends at its first output. The impulse from the third output of block 3 zeroed the counter 5 and D-flip-flops 8-10.

With the end of the pulse at the third output of the control unit 3, a new cycle of control of the rotational speed begins, carried out by measuring and monitoring the duration of the period T |. At the same time, in the counter 5, during the period TI, the counting of the pulse of the CRP 4 is performed. Information on the number of pulses Mi accumulated in the counter 5 is continuously fed to the input of the decoder 7.

The number NJ of pulses accumulated in the counter 5 depends on the frequency of rotation of the object under study, which is directly proportional to the frequency of the signals from sensor 1, and determines the operation of the decoder 7, D-flip-flops 8-10 and accumulators 20-22 in accordance with the table.

The state of the flip-flops 8-10 is changed by the action of the corresponding output pulses of the decoder 7 and the control pulse from the third output of block 3, and the state of the accumulators 20-22 depends on the state of the flip-flops 8-10 and changes at the moment of arrival on the L 14 circuit. -19 pulses from the second output of control unit 3 (see Fig. 5).

Therefore, after submitting to the proposed

the power supply voltage device and the subsequent start-up of the object under investigation (Fig. 2) the frequency of the signals of sensor 1 will increase from the values fi FH1 (I frequency range in Fig. 2), which corresponds to the following period T in Fig. 5, and upon reaching the values of the frequency band II (periods Tz-1 in Fig. 5), the accumulator 22 in accordance with the table will generate an output signal. However, this signal will not

transmitted through the driver 25 to the output of the device, since the second input of the driver 25 has a inhibitory signal. When the frequency of the sensor signals 1 values in the range

inclusions (IV frequency range in Fig. 2, periods Td in Fig. 5), the drive 21 will generate an output signal that sets the trigger 24 to the operating state. From the output of the trigger 24 to the second input of the imager

25 an enable signal will be given. If further the rotational speed decreases and the frequency of the signals of sensor 1 reaches values in the second range (periods T2-2 in Fig. 5), then the drive

22 will generate an opening signal that will be fed to the third input of the imaging unit 25 and the device will generate an output command indicating an emergency lowering of the rotation frequency (FH1 fi s

Ph).

If, however, the rotation frequency, instead of a decrease, increases and the frequency of the signals from sensor 1 is in the fifth range (periods Ts in Fig. 5), then the accumulator 20 will generate

the opening signal that will be fed to the first input of the imaging unit 25 and the device will generate a command indicating an emergency increase in the rotational speed (FBI ft - 82) in both cases of the frequency output of the sensor 1 signals beyond the specified limits; device command, indicating a violation of the nominal (operating) mode of the object under study.

The proposed device allows controlling the frequency output outside the operating range. At the same time, the device switches to the control mode when the frequency of the sensor signals reaches 1

included in the switching range (IV frequency range in Fig. 2, frequencies from Rvc to FBI). With the subsequent emergency frequency increase {curve 2 in FIG.

2) when it goes to the upper range of the device response frequency (V frequency range in Fig. 2, frequencies from FBI TO Fsa) or when it is emergency low (curve 1 in Fig. 2) and goes to the lower response frequency range (And frequencies, frequencies from Pf to Pn), the proposed device forms the corresponding output command.

The newly introduced elements of the flowchart 0-flip-flop8, the element IL-11, the drive 20 together with the decoder 7 and the elements 14 and 15 allow to narrow the upper frequency range of the device operation (V dash frequency in Fig. 2) and execute m -fold confirmation of the presence of a frequency in the specified range.

In this case, the immunity of the device is ensured when operating under the influence of interference. Let us show it with examples.

Let m - 2 and Pva / / FBI TV2 / TV1 -1, where TBI 1 / F2 TWa -1 / PB- |, as shown in FIG. 2 and 3, where Ci is the speed sensor signal corresponding to the beginning of the monitored period.

In this case, the device will form the output command only after measuring two consecutive periods T | sensor signal 1, each of which has a duration of TV T,

TB2Input signals can be either sensor 1 signals or noise signals. Therefore, at the occurrence of interference Hi at the time from ti to t2, a time interval Tsch is formed, with Tv- | TSV TWA (Fig. For).

If the second signal C2 of the sensor 1 arrives at the input of the device at the moment of time from t3 to t4, then a second time interval Tpa with a duration of TBI Tp2 Tv2 will be obtained and the device will generate a false output command.

If the signal C2 arrives before the moment of time ta, then Tp.2 TV {takes place and the device will not generate an output command. Therefore, the maximum value T i max2 of the period of the signals of the sensor 1, at which the device turns out to be noise-resistant, will take place at T s s Tri2 TBI and will be equal (Fig. 36)

T | max2 2-TBv

Similarly, for the case of m 3 (Fig. Sv), we will have T, tahz ZTV. I. Finally, for m - iVi, we have T | tfm - M TBI.

five

0

five

0

five

0

five

0

The transition from the period duration to the frequency, from the last expression we obtain the minimum value of the frequency of the signals of the sensor 1, at which the operation of the device is ensured with noise immunity (Fig. 3)

M

0

TI gpahad 2 1 7ГТв7

From the dependence tribute and FIG. 3 it follows that the larger the number m, the wider the frequency of the signal of the speed sensor in which the noise immunity of the device is ensured. Having chosen the value m m - Ki / SK, so that Timax M P, where HL is the threshold value of the frequency of the signals of sensor 1, at which the amplitude of the signal of the sensors chiH 1 becomes less than the threshold of the driver of the shaper 2, it is possible to ensure the noise-resistant operation of the device at l, about the frequency of rotation.

The newly introduced elements of the block diagram D-trigger 10, element OR 13, accumulator 22, together with decoder 7 and elements 18 and 19, limit the lower range of the device response frequency (range II in Fig. 2) and perform an n-fold expansion. confirmation and “frequencies in the specified range.

At the same time, noise immunity of the device is ensured when operating under conditions of short-term loss of the speed sensor signals. So, for example, let Pn2 / Pn1 Tn2 / Tn1 1 be selected, where Tsch - 1 / FH2 and Tn2 I / FHI, kcc are shown in Figs 2 and 4, where Ci, C2, Cz and C are respectively the first to fourth sensor signals speed. If n 1 and there are no interferences and disappearances of the signals of sensor 1, then the device, when the rotation frequency decreases, will form the output command only at Т Т | Tn2

However, in some cases of loss of signals from sensor 1 when item 1, the device may form a false command. Thus, for example, the device issues a false command when signals 0.2 are lost (Fig. 4a) and the signal C3 arrives at the time between ti and t2. Here, the condition of forming a false command is determined as follows (see Fig. 46).

Tsch 2T, TH2,

eleven

g- Тщ Т | - Tn2

or 2 Ph2 f 2 FHI

If we accept n 2, then in this case the disappearance of one signal will not lead to the formation of a false output command.

Another case is the formation of a false command when two adjacent signals C2 and C3 hit and the signal C4 arrives at the time between c and t2 (Fig. 4c), i.e. subject to (Fig. 4d):

Titus

j THI T | -g Tn2.

3 Ph2 3 FHI

However, in this case, by adopting item 2, it is possible to avoid the formation of a false command by the device. Similarly, the false operation of the device is eliminated when 3 or more speed sensor signals are lost.

At the same time, the accumulator 21 ensures that the indicator switches on in the control mode after K-cracking confirmation of the presence of a frequency in the switch-on range (band IV in FIG. 2), which increases the noise immunity of the device operation during the switch to control mode.

Claims (2)

Claim 1. Limit indicator, rotational speed values containing series-connected rotation speed sensor, input driver and control unit, as well as reference frequency generator, counter, initial installation unit, decoder and six AND elements, the output of the reference frequency generator connected to the second inputs of the control unit and the counter, the output of the counter is connected to the input of the decoder, and the third input of the counter to the third output of the control unit, characterized in that, in order to increase the In this case, four D-triggers, four OR elements, three threshold accumulators and a shaper of output commands are entered into it, the first output of the control unit is connected to the first input of the counter, the second output - to the first inputs of each of the elements, And the first output of the decoder is connected to C - the input of the first D-flip-flop, the second output of the decoder - with the C-input of the second D-flip-flop and the first input of the first OR element, the third output of the decoder - with the first input of the second OR element, the fourth output of the decoder - with the C-input of the third D- trigger, fifth exit decoder -c third input of the control unit and the first input of the third OR gate, a third control unit output is connected to second inputs of the first, second and third elements or the outputs of which are connected respectively to the inputs of the H-ervogo, second and third D-flip-flops, direct outputs of the first, second and third D-flip-flops are connected respectively to the second inputs of the first, third and fifth elements And, inverse outputs of the D-flip-flops are connected respectively to the second inputs of the second. the fourth and sixth elements And, the output of the first element And connected to the first input of the first threshold accumulator, the output of which is connected to the first input of the output command of the output commands, and the second input to the output of the second element And, the output of the third element And connected to the first input of the atomic threshold accumulator, the output of which is connected to the C input of the fourth D trigger, and the second input to the output of the fourth OR element, the second input of which is connected to the output of the initial setup block and the R input of the fourth D flip-flop, and the first input connected to the output of the fourth element And, the output of the fifth element And is connected to the first input of the third threshold accumulator, the output of which is connected to the third input of the output instructions generator, and the second input - to the output of the sixth element I, the output of the fourth D-flip-flop is connected to the second input of the output command driver, while the D-inputs of the D-flip-flops and the input of the initial installation block are connected by a potential power bus. 2. The signaling device according to claim 1, characterized in that the output command driver comprises the seventh and eighth AND elements and the fifth OR element, the first input of the output command shaper connected to the first input of the seventh AND element, the output of which is connected to the first input of the fifth the OR element and the first output of the output driver, the second input of the driver output commands are connected to the second input of the seventh And element and the first input of the eighth And element, the second input of which is connected to the third input of the output command generator, and the output of the eighth And element to the third output of the output command generator and the second input of the fifth OR element, the output of which is connected to the second output of the output of the output commands, IP j№ff " ÑС or -Ll f, (te fia L ftff t , 1 / Um   1 / b Nee g Theme 1 / fgffa NHisTH1-1irH2 Mhzs Akl tH tgt Fig 2 it tz t3 u t FIG. four B TO if SNS but b i FIG. 7