CN109653799B - Gas alarm different from traditional structure and implementation method - Google Patents
Gas alarm different from traditional structure and implementation method Download PDFInfo
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- CN109653799B CN109653799B CN201811599655.XA CN201811599655A CN109653799B CN 109653799 B CN109653799 B CN 109653799B CN 201811599655 A CN201811599655 A CN 201811599655A CN 109653799 B CN109653799 B CN 109653799B
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- 239000003990 capacitor Substances 0.000 description 7
- 239000003245 coal Substances 0.000 description 7
- 230000000630 rising effect Effects 0.000 description 5
- 238000005065 mining Methods 0.000 description 4
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
- E21F17/18—Special adaptations of signalling or alarm devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
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Abstract
The invention discloses a gas alarm and an implementation method which are different from the traditional structure, wherein the gas alarm comprises a gas sensor signal circuit, a reference voltage circuit, a comparator circuit, a positive feedback circuit, a multivibrator circuit and an audible and visual alarm circuit. The gas sensor signal circuit is connected with the same-phase end of the comparator circuit A1; the reference voltage circuit is connected with the A1 inverting terminal; the output end of the comparator A1 introduces positive feedback to the in-phase end through a resistor network R2/R1; when the gas concentration is increased, the output signal voltage of the gas sensor signal circuit is reduced, the roles of the reference end and the input end of the hysteresis comparator are reversed due to the existence of the reverse diodes D1 and D2, A1 becomes an inverted input hysteresis comparator added with the reference voltage, a multi-vibrator circuit is formed by a resistance-capacitance network between the output end and the inverted end of the comparator and the comparator, and the multi-vibrator circuit generates a rectangular wave signal to drive the alarm circuit to work, so that audible and visual alarm is generated.
Description
Technical Field
The invention relates to a technology of a portable gas alarm module with an unusual structure, in particular to a circuit structure which is different from the traditional gas alarm that the output of a comparator circuit is utilized to drive the work of an oscillator circuit, thereby changing the design convention that the original alarm circuit is generally composed of the comparator circuit and the oscillator circuit. The design is unique, and combines the comparator and the oscillator into a whole, so that the comparator circuit has the functions of comparison and oscillation, the gas alarm circuit has the advantages of simpler structure, lower cost, more stable work and higher sensitivity, and is a novel attempt. The unusual gas alarm circuit structure can also alarm various other environments such as water level, temperature, pressure and the like.
Background
In modern coal mine enterprises, in order to ensure the safety of people property and life, the safety facility can be said to be armed to the teeth, wherein the gas alarm is one of the most important safety devices, and any one of the middle and large coal mines meeting production conditions just can reduce the occurrence probability of the current coal mine gas explosion to the minimum due to the wide use of the gas alarm, so that the design of the gas alarm is one of the important conditions for ensuring the safe production of the coal mine, and whether the design of the gas alarm is advanced, concise, stable and efficient is ensured.
In practical application, if an alarm design is to be implemented on the gas concentration in the working surface environment of the coal mine bottom, the analog voltage value obtained by detecting the gas concentration at the bottom of the coal mine is generally used as the voltage of the non-inverting input end of a general comparator, a fixed reference voltage is arranged at the inverting end of the comparator (in order to realize zero setting of the bridge, the reference voltage value can be adjusted sometimes, but is still a fixed value after the zero setting is finished, so that the reference value is assumed to be a fixed value for convenience of description), the output quantity of the gas sensor is changed along with the change of the gas concentration at the bottom of the coal mine, the sign of the difference between the output quantity and the reference value is changed once, the output polarity of the comparator is changed immediately, so that an oscillator connected with the comparator is triggered to vibrate, and an oscillation signal drives a loudspeaker to sound.
Therefore, the common portable gas alarm circuit generally consists of a general comparator circuit and an oscillating circuit, which are indispensable. The design has the advantages of mature technology and wide application, but the design of the alarm circuit is not very concise and has higher design cost.
The design can enable the reference voltage value of the comparator to change in an exponential curve along with the change of the output polarity of the comparator, so that the sign of the difference value between the output quantity of the gas sensor and the reference value regularly changes, and finally, the comparator has the functions of both a comparator and an oscillator, and the comparator circuit and the oscillator circuit are combined into a whole.
The gas alarm module circuit can be universally applied to alarm of various industrial and mining environments, such as the change of water level, temperature, pressure and the like of the industrial and mining environments, has wide application range and high cost performance.
Disclosure of Invention
The technical problem to be solved by the invention is to provide the gas alarm equipment which is simpler in structure, lower in manufacturing cost, more reliable in use and higher in sensitivity and is different from the conventional design.
In order to achieve the above object, the present invention provides a gas alarm and a method for implementing the same, which are different from the conventional structure, and include a gas sensor signal circuit, a reference voltage circuit, a comparator circuit, a positive feedback circuit, a multivibrator circuit, and an audible and visual alarm circuit. The output signal of the gas sensor signal circuit forms the in-phase terminal voltage U+ of the comparator circuit A1 through a diode D2 and a resistor R1 which are connected in a reverse direction; the reference signal generated by the reference voltage circuit forms an inverted terminal voltage U-of the comparator circuit through a diode D1 which is reversely connected; the output end of the comparator A1 introduces positive feedback to the same phase end through a resistor network R2/R1, so that A1 forms a hysteresis comparator circuit; when the gas concentration is increased, the signal circuit of the gas sensor outputs a signal voltage U A The reference voltage end role and the signal input end role of the hysteresis comparator are reversed due to the existence of the reverse diodes D1 and D2, the comparator A1 becomes an inverted input hysteresis comparator added with the reference voltage, and the reference voltage is the output signal voltage U of the current sensor A The method comprises the steps of carrying out a first treatment on the surface of the The multi-vibrator circuit is formed by a resistor-capacitor network R3/C1 between the output end of the hysteresis comparator A1 and the inverting input end of the hysteresis comparator A1 and the comparator, so that the comparator A1 has both an oscillating function and a comparing function, the oscillating function and the comparing function are combined into a whole, and the multi-vibrator circuit generates a rectangular wave signal to drive the alarm circuit to work, and audible and visual alarm is generated.
The sensor signal circuit is sequentially connected in series with 12V power supply, a compensation end C of the gas sensor, a potentiometer P2, a detection end D of the gas sensor and a working place, and outputs a gas sensor signal voltage U from a sliding arm of the potentiometer P2 A 。
The reference voltage circuit is sequentially connected with 12V power supply, a resistor R5, a potentiometer P1, a resistor R6 and a working ground in series, and outputs a reference signal voltage U from a sliding end of the potentiometer P1 B 。
Drawings
Fig. 1, 2 and 3 are provided to provide a further understanding of the present invention and form a part of this application, and fig. 1 is a circuit configuration diagram of a conventional alarm. Fig. 2 is an electrical schematic diagram of an unusual gas alarm module circuit. Fig. 3 is a multivibrator keypoint waveform based on hysteresis comparators.
Detailed Description
Brief description of circuit structure of traditional gas alarm circuit:
conventional gas alarm circuits generally comprise a comparator circuit and an oscillator circuit, and as shown in fig. 1, the circuit is a typical conventional alarm circuit, and in order not to be repeated with the important parts in the present document, an overtemperature alarm circuit of a transformer common to industrial and mining enterprises is used for replacing the conventional gas alarm circuit, and the structures of the circuit are basically similar.
The circuit is to use a current transformerSB 1 、SB 2 The positive temperature coefficient thermistor RT (sensor) is immersed in transformer oil, which is connected to a certain two-phase line of a three-phase power supply.SB 1 、SB 2 AC voltage induced by secondary side passes through rectifying tubeVD I Rectifying and resistanceR 1 CapacitanceC 1 After the filtering, a certain potential is provided at the point a, and this potential is used as a reference potential of the comparator (operational amplifier uA 741).
When the oil temperature increases, the resistance of RT increases, so that the 3-pin potential (sensor output potential) of the operational amplifier is greater than the 2-pin (A point, reference potential) potential, thusIC 1 To make the transistor output high level by 6 pinsT 1 、T 2 And capacitorC 2 And an audio oscillator consisting of the loudspeaker works, so that the loudspeaker and the LED send out audible and visual alarm signals.
Design of a gas alarm module circuit with a comparator and an oscillator integrated into a whole:
the purpose that this design was to realize is, when the gas sensor output voltage that is used by the colliery working face environment of being monitored and being measured falls below the reference voltage, monitor circuit can use sound and flash to report to the police this change, and this gas alarm module circuit uses operational amplifier to constitute a comparator, is different from traditional alarm circuit, and the reference terminal voltage of this comparator in the gas alarm circuit can be the exponential type change along with the polarity change that the comparator output, so this operational amplifier circuit can play the effect of comparator and oscillator simultaneously, two combine into one. The electric principle of the gas alarm module circuit is shown in figure 2.
In fig. 2, it can be seen that the system circuit includes 6 module circuits such as a gas sensor signal circuit, a reference voltage circuit, a comparator circuit, a positive feedback circuit, a multivibrator circuit, an audible and visual alarm circuit, and the like.
ResistorR 5 PotentiometerP 1 Resistance of resistorR 6 Reference voltage generating circuit constituting a measuring bridge byP 1 The balance of the bridge can be adjusted; detection end D and compensation end C of gas sensor and potentiometerP 2 Form a sensor signal circuit byP 2 The sensitivity of the alarm can be adjusted.
Reverse diodeD 2 And a resistorR 1 The sensor signal input circuit is composed, the A end in figure 2 is the sensor voltage input end, the A end voltage enters the comparator through the sensor signal input circuitA 1 Form the in-phase input terminalU + A voltage.
Reverse diodeD 1 Forming a reference voltage input circuit, the terminal B in figure 2 is a reference voltage input terminal, and the reference voltage B passes throughD 1 Enter comparatorA 1 Form an inverting input terminalU — A voltage. DiodeD 1 Is very effective in forming reference voltage oscillations.
ResistorR 4 Light emitting diodeD 3 Forming an optical alarm circuit; the transistor T and the loudspeaker LS form an acoustic alarm circuit.
Resistor networkR 2 /R 1 A positive feedback circuit of the comparator is formed.
Operational amplifierA 1 A voltage comparator circuit is formed to compare the sensor voltage with a reference voltage.
By capacitanceC 1 ResistorR 3 Differential circuit and comparatorA 1 Forming a multivibrator circuit, the comparator output is continuously inverted due to the diodeD 1 Is reversed to result in capacitanceC 1 Charging and discharging are continuously carried out through the resistor, so that a sawtooth wave oscillating signal is formed.
By operational amplifierA 1 Forming a hysteresis comparator with the positive feedback network:
due to voltage comparatorA 1 The alarm circuit has very high gain, and if no measures are taken, even if the input voltage of the comparator is extremely small, the output of the comparator can be turned over, so that a large amount of switching noise is generated, and the alarm circuit is extremely easy to misreport and is not needed.
To avoid this, the current is passed through a resistor networkR 2 /R 1 The non-inverting input of the comparator is provided with a positive feedback network, which is composed of an operational amplifierA 1 And a positive feedback network. The hysteresis characteristic of the hysteresis comparator is composed of resistance ratioR 2 /R 1 Determining, i.e. determining, the rising edge threshold voltage of the hysteresis comparatorU T2 And falling edge threshold voltageU T1 Is a value of (2).
Due to operational amplifierA 1 The comparison function and the oscillation function are combined into a whole, and the roles of the input end and the reference end of the comparator are about to be reversed under normal conditions and alarm conditions, so that the special design is not easy to understand.
This can be understood in normal situations, i.e. in situations where the industrial and mining environment is not alerted: sensor output voltageU A Is the input end of the hysteresis comparator and the referenceVoltage (V)U B The reference voltage input end of the hysteresis comparator is the threshold voltage calculation at the moment is complex, and the state under the alarm condition is mainly discussed, so that the calculation of the threshold voltage is omitted at the moment. Under normal conditions, the comparator outputs a high level and the alarm is silent.
Once the output voltage of the gas sensor is increased due to the rising of the gas concentrationU A The value falls to the threshold voltage of the falling edge of the comparator under normal condition, and then is reduced by an infinitesimal amount, the output of the comparator is immediately inverted to the 0 level, and the circuit enters an alarm state.
After the circuit enters an alarm state, the voltage of the inverting terminal of the comparatorU - Due to capacitanceC 1 The charge-discharge function of (a) is in an oscillation state, so that the input end of the hysteresis comparator becomesU - The voltage is inverted at the reference terminalU A Because the gas concentration signal at this time is a fixed value, the circuit actually becomes a hysteresis comparator with the inverting input of the reference voltage (actually, the gas concentration signal voltage) added, and the threshold voltage of the hysteresis comparator is obtained by the following steps:
order theU — =U + The obtainedU — The threshold voltage at this time is thus given by:
in the two formulasU CC =12V。
Detailed explanation of the working process of the gas alarm circuit
Under the condition of normal gas concentration, the output voltage of the comparator is 12V at high level, and the LED is provided with a high-voltage power supplyD 3 The transistor T is turned off and the horn LS remains in a mute state.
An increase in gas concentration results in a sensor output voltageU A The output of the comparator is inverted to low level "0" and the LED is loweredD 3 Emitting light; the transistor T is conducted, the direct-current voltage passes through the loudspeaker LS instantly, and the circuit is about to enter an alarm state.
Due to the light-emitting diodeD 3 On-state light emission, so the feedback network R 2 /R 1 How much can makeU + The voltage is reduced a little, and the positive feedback depth of the comparator is further deepened.
12V power supply pair capacitorC 1 Through resistance R 3 And the output end (6 feet) of the comparator charges, because the capacitor has the characteristic that the terminal voltage can not be suddenly changed, at the moment that the output of the comparator is reversed to low level, the capacitorC 1 The lower voltage (i.e. the voltage at the inverting terminal of the comparator 2) remains at the original level, along with the capacitanceC 1 Charging proceeds with comparator inverting terminal voltageU - Exponentially decreasing as shown in U of FIG. 3 - Shown therein, whereinU T1 、U T2 The falling and rising edge threshold voltages of the hysteresis comparator respectively,U+ ， andU+ ，， the same-phase terminal voltages of the comparator corresponding to the rising edge threshold voltage and the falling edge threshold voltage are respectively obtained.
Diode with reduced voltage at inverting terminal of comparatorD 1 Cut-off, the voltage at the B terminal (i.e. the original reference voltage) no longer affects the voltage at the inverting terminal of the comparatorU -- When the comparator is at the inverting terminalU -- Voltage drop to the threshold voltage determined aboveU T1 Then the output end of the comparator is turned to be 12V with high level, and the LED D is turned to be a small quantity 3 And the transistor T is turned off, and no current passes through the horn LS.
Due to the light-emitting diodeD 3 Cut-off of luminescence, so the feedback networkR 2 /R 1 How much can makeU + The voltage increases a little, making the positive feedback depth of the comparator further deepen.
Comparator outputCapacitor at moment of turning end to high levelC 1 The lower voltage is still kept at the original level, and the 12v high level passes through the resistor againR 3 Pair capacitorC 1 Reverse charging is performed, along with the capacitanceC 1 The reverse charging proceeds with the comparator inverting terminal voltage rising exponentially.
Comparator inverting terminalU -- The voltage gradually rises to the threshold voltageU T2 When an infinite small amount is added, the output end of the comparator is inverted to be 0 level, and the light emitting diode is re-lightened; transistor T is turned back on and the dc voltage is instantaneously applied to horn LS.
So as long as the output voltage of the gas sensor (namely the voltage of the A terminal) is lower than the preset value, the diode is connected reverselyD 1 Is present, the voltage at the inverting input of the comparatorU -- The signal will oscillate at a certain frequency and the led will flash at a certain frequency; the transistor T is turned on or off at a certain frequency, and the loudspeaker LS emits an alarm sound through pulse direct current at a certain frequency, as shown in figure 3.
The period of the alarm signal can be calculated simply by the following formula:
t≈2R 3 C 1 ln（1+2 R 1 /R 2 ）
wherein t is in seconds; the resistance unit is ohm; the capacitance unit is Farad.
Ending the alarm process of the gas alarm:
the concentration of the gas is recovered to be normal,U A voltage rise, U + The voltage also has to be increased as long as U - Is reduced to U at a certain moment + When the infinite small amount is reduced, the strong positive feedback will turn the comparator output to high level, and the comparator constantly outputs high level without oscillating, as shown in fig. 3, because the roles of the reference and input of the comparator are shifted again at this time, and the alarm process is ended.
The alarm module circuit skillfully switches the diode D 1 Reverse connection, then use capacitor C 1 Is charged and discharged by (a)And a function of converting the original stable reference voltage into an unstable oscillation voltage, and comparing the oscillation voltage with the output signal of the gas sensor to enable the comparator to output a rectangular wave oscillation signal. Thus, the design convention that the original alarm circuit is usually composed of a comparator and an oscillator is changed, and the method is a novel attempt.
The design is subjected to simulation test of a simulation circuit, and the circuit structure is perfect and the element parameters are accurate.
Claims (1)
1. The gas alarm is characterized by comprising a gas sensor signal circuit, a reference voltage circuit, a comparator circuit, a positive feedback circuit, a multivibrator circuit and an audible and visual alarm circuit; the gas sensor signal circuit is powered by 12V, and is provided with a compensation end C and a potentiometer P of the gas sensor 2 The detection end D of the gas sensor and the working place are connected in series in sequence, and the slave potentiometer P 2 The sliding arm of (2) outputs the signal voltage U of the gas sensor A The reference voltage circuit is powered by 12V and has a resistor R 5 Potentiometer P 1 Resistance R 6 Sequentially connected in series with working places, and is driven by a potentiometer P 1 Is used for outputting a reference signal voltage U B An output signal U of the gas sensor signal circuit A By means of reversely connected diodes D 2 Resistor R 1 Forming the comparator circuit A 1 Is the in-phase terminal voltage U of + The method comprises the steps of carrying out a first treatment on the surface of the The reference signal U generated by the reference voltage circuit B By means of reversely connected diodes D 1 Forming an inverted terminal voltage U of the comparator circuit - Comparator A 1 Through a resistor network R 2 /R 1 To A 1 The positive feedback is introduced at the same phase end to lead A to 1 Form a hysteresis comparator circuit, when the gas concentration is increased, the output signal voltage of the gas sensor signal circuit is reduced, and the backward diode D is used for 1 、D 2 Is to reverse the roles of the reference terminal and the input terminal of the hysteresis comparator, and the comparator A 1 Becomes a reference electricVoltage inverting input hysteresis comparator, the reference voltage is the current sensor output signal voltage U A Hysteresis comparator A 1 Resistance-capacitance network R between output terminal and inverting terminal 3 /C 1 Together with the comparator, form a multivibrator circuit as described, so that comparator A 1 The multi-resonant oscillation circuit has the oscillation function and the comparison function, combines the oscillation function and the comparison function into a whole, and the multi-resonant oscillation circuit generates a rectangular wave signal to drive the alarm circuit to work so as to generate audible and visual alarm.
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| CN201811599655.XA CN109653799B (en) | 2018-12-26 | 2018-12-26 | Gas alarm different from traditional structure and implementation method |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3359429A (en) * | 1964-03-23 | 1967-12-19 | Tektronix Inc | Trigger generator circuit having synchronized astable input oscillator |
| CN2175439Y (en) * | 1993-07-11 | 1994-08-24 | 石宝 | Non-contact electronic buzzing and flashing device |
| KR20010091653A (en) * | 2000-03-17 | 2001-10-23 | 곽정소 | Charging control circuit of battery in automobile |
| CN205714289U (en) * | 2016-04-27 | 2016-11-23 | 北京联合大学 | Portable gas explosion transfinites monitor |
| CN206671415U (en) * | 2017-03-27 | 2017-11-24 | 山西工程技术学院 | LED indicator type tri-state voltage alarms |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9374048B2 (en) * | 2013-08-20 | 2016-06-21 | Semiconductor Energy Laboratory Co., Ltd. | Signal processing device, and driving method and program thereof |
| CN209483427U (en) * | 2018-12-26 | 2019-10-11 | 山西工程技术学院 | A kind of supernormal portable gas explosion alarm appliance |
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- 2018-12-26 CN CN201811599655.XA patent/CN109653799B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3359429A (en) * | 1964-03-23 | 1967-12-19 | Tektronix Inc | Trigger generator circuit having synchronized astable input oscillator |
| CN2175439Y (en) * | 1993-07-11 | 1994-08-24 | 石宝 | Non-contact electronic buzzing and flashing device |
| KR20010091653A (en) * | 2000-03-17 | 2001-10-23 | 곽정소 | Charging control circuit of battery in automobile |
| CN205714289U (en) * | 2016-04-27 | 2016-11-23 | 北京联合大学 | Portable gas explosion transfinites monitor |
| CN206671415U (en) * | 2017-03-27 | 2017-11-24 | 山西工程技术学院 | LED indicator type tri-state voltage alarms |
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