RU2400929C1 - Device for generating pulses from signals of rotational frequency inductance pickup - Google Patents

Abstract

FIELD: physics. ^ SUBSTANCE: device has two comparators, one connected directly and other through an inverter to an input signal source. The device also has a frequency metre whose input is connected to the output of the second comparator, and a timer whose start input is connected to the output of the first comparator, the first control input is connected to the output of the frequency metre, the second control input is connected to the output of the second comparator, and the outputs are respectively connected to control inputs of the comparators. ^ EFFECT: simplification of the device and wider range of measurement for making the device using modern microcontrollers. ^ 3 dwg

Description

The present invention relates to measuring equipment and can be used in automatic measurement, control and emergency protection systems, which include sensors that generate bipolar signals, in particular induction sensors of speed and flow.

A device for generating pulses from the signals of induction speed sensors [1], based on the principle of selection of the input signal by area. Its disadvantage is the lack of reliability due to the fact that only one signal polarity is used to generate pulses from the signals of the induction speed sensors.

Of the known closest in technical essence is a device that implements a method of generating pulses from signals of induction speed sensors [2]. Its structural diagram is shown in figure 1, and figure 2 presents the waveform of the output signal of the induction speed sensor.

The device comprises a volt-second area measurement unit S _{1 of the} first half-wave of the bipolar signal e _{from the} induction rotation sensors 1, a memory unit 2, a comparison unit 3, an inverter 4, a volt-second area measurement unit S _{2 of the} second half-wave of the second half-wave of the bipolar signal e _{from the} induction speed sensors 5 and a control unit 6. The output signal e _with inductive sensors the rotational speed is fed to the inputs of the measurement unit volt-second area S ₁ of the first half-cycle of the bipolar signal e _with inductive rotation sensor 1, the control unit Nia 6 and through an inverter to the input unit 4 volt-second measurement area S ₂ of the second half-cycle of the bipolar signal e _with inductive sensors the rotational speed memory unit 5. The outputs of the measurement unit 2 and the volt-second area S ₂ of the second half-cycle of the bipolar signal e _with frequency induction sensors rotations 5 are connected to the comparison inputs of the memory unit 2. The second output of the memory unit 2 is connected to the input of the threshold setting Spor1 of the comparison unit 3 and the input of the control unit 6. The outputs of the control unit 6 are connected respectively to the inputs comparing board units 3 and memory 2, and inputs the measurement control units volt-second area S ₁ of the first half-cycle of the bipolar signal e _with inductive rotation sensor 1 and S ₂ of the second half-cycle of the bipolar signal e _with inductive sensor 5 speed.

The work of induction speed sensors is based on the Faraday law, according to which the induced EMF e _s is determined by the rate of change of the magnetic field Ф, coupled to a coil of W turns [3]:

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In the case under consideration, a change in the magnetic field is caused by the intersection of the field lines of the sensor magnet field with the protrusions of a rotating pathogen [4]. When the pathogen enters the magnetic field in the coil, the first half-wave of the signal is induced, and when it exits, the second half-wave is of opposite polarity (Fig. 2).

The volt-second area S _{1k of the} first half-wave of such a signal is approximately equal to the same area S _{2k of the} second (opposite polarity) half-wave, and the ratio of these areas R = S _1k / S _{2k is} close to 1, does not depend on the error in setting the gap between the sensor and the exciter, characteristics the pathogen itself and remains constant over a wide range of speeds. The amplitude of the signal e _c increases linearly with increasing speed, and the duration decreases.

The device operates as follows. The control unit 6 consists of threshold elements (comparators). When the input signal exceeds _a predetermined e to the comparators 6, the detection threshold control unit produces enable signal measurement S ₁ and fed to the measurement unit volt-second area of the block 1. The measurement volt-second area of the input signal 1 is carried out _with e integration as long as the input signal e _c does not become less than the detection threshold set in the control unit 6. In this case, the output signal of the volt-second area measurement unit 1 reaches the value S _1k . If the value of S _1k exceeds the threshold value of S _av.min , equal to the limiting minimum allowable value of the volt-second area of the studied signal half-waves S _1k > S _av.min , and the control unit 6 detects the second half-wave of the signal e _s , then the output of the control unit 6 will appear signal s ₂ measurement resolution in the measurement unit volt-second area 5 during the action of the second half-wave signal e _s, and a permission signal comparing the current measurement result s _xk with the threshold value s _por1 = Q · s _1k (Q slightly less than one) is formed in th memory unit 2 from S ₁ to the signal.

In comparison block 3, the areas S _xk with S _por1 or S _xk with S _1k are compared. In the cases S _2> S or S _{xk por1} ≈S _1k produced the desired pulse.

The disadvantage of this device is its complexity, namely the use of integrators with discharge circuits, as well as control and comparison units containing a large number of comparators. In addition, when implementing the device using modern microcontrollers, the measurement range in the region of high rotational speeds is limited, since for the digital integration operation, the ADC of the microcontroller must provide a sufficiently large number of samples during one half-wave of the signal e _s .

The present invention is aimed at simplifying the device and expanding the measuring range when implementing the device using modern microcontrollers. This is achieved by the fact that in the pulse shaper from the signals of the induction speed sensors, containing two comparators, one directly connected, and the second through an inverter with an input signal source, according to the invention, a frequency meter connected at the input to the output of the second comparator, and a timer, the start input of which is connected to the output of the first comparator, the first control input is connected to the output of the frequency meter, the second control input is connected to the output of the second compa ora, and outputs connected respectively to the control inputs of the comparators.

Figure 3 shows the structural diagram of the proposed device pulse shaper from the signals of induction speed sensors. The device consists of an inverter 1, comparators 2 and 3, a timer 4 and a frequency meter 5.

The bipolar signal of the induction speed sensor e _s is supplied to the input of the comparator 2 and through the inverter 1 to the input of the comparator 3. The output of the comparator 2 is connected to the start input of the timer 4, and the output of the comparator 3 is connected through the frequency meter 5 to the first control input of the timer 4, the second control the input of which is connected to the output of the second comparator 3. The output of the comparator 3 is the output of the required pulse, and the output of the frequency meter 5 is the output of the result of measuring the speed 7. The outputs of the timer 4 are connected respectively to control inputs of comparators 2 and 3.

All elements that make up the device can be implemented as separate functional units or programmatically using a microcontroller equipped with comparators and a timer. The implementation of the newly introduced timer is much simpler than the implementation of volt-second area measuring units containing integrators with charge and discharge circuits, and a control unit that ensures timely switching of charge and discharge circuits. The introduction of a frequency meter does not complicate the implementation of the device as a whole, since the pulse shaper from the signals of induction speed sensors is designed specifically for measuring the frequency.

The device operates as follows. The threshold of operation of the comparator 2 is set equal to half the minimum possible amplitude of the signal of the induction speed sensor e _s . By choosing the thresholds for the operation of the comparators 2 and 3 equal to half the minimum possible amplitude of the signal of the induction speed sensor e _s , the device is provided _with stable operation if the entire signal e is subjected _to unipolar interference that does not exceed the threshold for the operation of the comparators 3 and 4, as well as with alternating interference , out of phase signal e _with and satisfying the same condition. That is, the device provides stable operation with a ratio of signal amplitudes and interference of more than two. Powerful unipolar pulsed interference, having the same sign and the time of occurrence of one of the half waves signal e _s, also did not affect the operation of the device as a condition of excess signal e _with half its minimum possible amplitude is not disturbed.

When the input signal of the device becomes greater than the threshold of the comparator 2, the output pulse of the timer 4 appears. Timer 4 generates a pulse whose duration is equal to the expected duration of the second half-wave of bipolar pulses of the induction speed sensor. This pulse is supplied to the control input of the comparator 3, allowing it to work. If during the action of this pulse the second inverted half-wave of the input signal e _c exceeds half of its minimum possible amplitude, the comparator 3 will work, and the required pulse will appear at its output 6. After receiving at least two pulses at the output 7 of the device, the result of measuring the speed appears. The timer 4 generates control pulses of the comparators 2 and 3, the time of occurrence and duration of which depend on the moment the signal appears at the output of the comparator 3 and the frequency measurement results. At the beginning of work on the control input of the comparator 2 there is always a permission signal for work. If during the opening of the comparators 2 and 3 their operation does not occur, that is, the signal of the induction speed sensor is not detected at the expected time, then the device returns to its original state until two new pulses appear at output 6.

By introducing into the device a frequency meter connected at the input to the output of the second comparator and a timer, the start input of which is connected to the output of the first comparator, the first control input is connected to the output of the frequency meter, the second control input is connected to the output of the second comparator, and the outputs are connected respectively to the control inputs of the comparators simplify the implementation of the device.

Information sources

1. Patent RU 2173022 C2, IPC7 N03K 5/153, publ. August 27, 2001

2. Patent RU 2352058 C1, IPC Н03К 5/153, publ. 04/10/2009

3. Sensors of thermophysical and mechanical parameters. Directory. / Under the general editorship of Yu.N. Kopteva. Volume 1, M., publishing company of the journal "Radio Engineering", 1998, p. 52.

4. Sensors of thermophysical and mechanical parameters. Directory. / Under the general editorship of Yu.N. Kopteva. Volume 2, M., publishing company of the journal "Radio Engineering", 2000, p. 561, p. 616-618.

Claims (1)

A pulse generator from signals of induction speed sensors, containing two comparators connected directly and the second through an inverter with an input signal source, characterized in that a frequency meter is connected to it, connected at the input to the output of the second comparator, and a timer, the trigger input of which connected to the output of the first comparator, the first control input is connected to the output of the frequency meter, the second control input is connected to the output of the second comparator, and the outputs are connected respectively to ulation input of the comparator.

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