CN209070697U - A kind of detection system of imflammable gas - Google Patents

Abstract

The utility model relates to a kind of detection systems of imflammable gas, including power circuit, voltage regulator circuit, sensor, setting potential circuit, comparison circuit, amplifying circuit, fan control and warning circuit, the household imflammable gas leakage alarm of the design and ventilation device, entire technical solution takes the development scheme using only hardware, take full advantage of the characteristic of gas sensor and other elements, it is made to complement each other, to which the gas alarm device of the design has higher cost performance, with preferable performance, and it is cheap, it has a extensive future.

Description

A kind of detection system of imflammable gas

Technical field

The utility model relates to detection device field, the detection system of specifically a kind of imflammable gas.

Background technique

Popularizing for combustion gas (artificial coal gas, natural gas, liquefied petroleum gas), improves production efficiency, the quality of life of citizen, But during using combustion gas, because of the contingencies Shi Youfa such as gas explosion, poisoning caused by the reasons such as gas leakage, exhaust gas It is raw, serious threat is brought to the safety of life and property of people, therefore using combustion gas safely is always combustion gas authorities The most important thing of work.Fuel Gas Leak Alarm can effectively monitor the concentration of fuel gas or poisonous gas (such as CO) in environment, Once its concentration can issue sound and light alarm signal, and can automatically turn on exhaust fan and combustion gas is discharged beyond alarm limit value Outdoor, or even gas supply can be automatically cut off by linkage prevents combustion gas from continuing to leak, and plays the role of safety precaution.But Whether alarm is selected reasonable, is directly related to giving full play to for its function, and structure is complicated for detection system in the prior art, The controllers such as single-chip microcontroller are mostly used to be controlled greatly, total poor reliability, and higher cost, it is difficult to it obtains on a large scale It promotes and applies.

Utility model content

The technical problem to be solved by the utility model is to provide a kind of detection systems of imflammable gas, existing to solve Defect present in technology.

The technical solution that the utility model solves above-mentioned technical problem is as follows:

A kind of detection system of imflammable gas, including sequentially connected power circuit, voltage regulator circuit, sensor, compare Circuit, amplifying circuit, the amplifying circuit are connect with the fan control and warning circuit being connected in parallel respectively, and the sensor is set It is equipped with setting potential circuit connected in parallel；The power circuit provides 12V DC electricity to voltage regulator circuit after step-down transformer Source；The voltage regulator circuit is three terminal integrated voltage stabilizer LN7808；The sensor is gas sensor TGS813, the sensor It has been arranged in parallel thermistor or humistor compensates circuit, the comparison circuit and amplifying circuit are concatenated electricity Press comparator and amplifying triode.

The beneficial effects of the utility model are: fuel gas alarming ventilation device, takes the exploitation using only hardware Mode takes full advantage of the characteristic of gas sensor and other elements, it is made to complement each other.Its circuit structure is simple, uses Element is relatively fewer, substantially reduces its cost of manufacture, economical and practical, and adapted to that fuel gas alarm price gradually reduces becomes Gesture, cost performance with higher.

Detailed description of the invention

Fig. 1 is the utility model principle structural schematic diagram；

Fig. 2 is the utility model voltage and voltage regulator circuit schematic diagram；

Fig. 3 is the sensor circuit schematic diagram that the utility model has temperature compensation function；

Fig. 4 compares for the utility model and amplifying circuit schematic diagram；

Fig. 5 is the utility model alarm and fan control circuitry schematic diagram；

Specific embodiment

The principles of the present invention and feature are described below in conjunction with attached drawing, example is served only for explaining that this is practical It is novel, it is not intended to limit the scope of the utility model.

As shown in Figure 1, a kind of detection system of imflammable gas, including sequentially connected power circuit, voltage regulator circuit, biography Sensor, comparison circuit, amplifying circuit, the amplifying circuit are connect with the fan control and warning circuit being connected in parallel respectively, institute It states sensor and is provided with setting potential circuit connected in parallel；The power circuit provides after step-down transformer to voltage regulator circuit 12V DC power supply；The voltage regulator circuit is three terminal integrated voltage stabilizer LN7808；The sensor is gas sensor TGS813, The sensor parallel is provided with thermistor or humistor compensates circuit, the comparison circuit and amplifying circuit For concatenated voltage comparator and amplifying triode.

Concrete operating principle:

The workflow of concrete scheme is analyzed: power circuit provides the DC power supply of 12V to circuit by step-down transformer, The stable voltage of 8V is exported after the three-terminal voltage-stabilizing pipe of voltage regulator circuit, then by being compared after sensor with setting voltage Compared with.When imflammable gas concentration is not exceeded, the output voltage of sensor is smaller than setting voltage, to make in comparison circuit Voltage comparator reverse side exports low level, therefore is unable to the work of driving fan warning circuit.And work as imflammable gas concentration over-standard When, the output voltage of sensor will be greater than the voltage value of setting, to keep voltage comparator in-phase end output in comparison circuit high Level carries out signal amplification by amplifying circuit, and then the relay coil of output driving fan control automatically opens fan Continuous audible ringing signal is issued with audible alarm circuit.

Particular hardware circuit design:

One, power supply, voltage regulator circuit design:

Stable power supply is the power source of various electronic circuits, and the heart of circuit is described as by people.It is well known, all electricity consumptions Equipment has certain requirement to supply voltage including electronic instrument, household electrical appliance etc..The main packet of the power circuit of the design Include two parts: the selection of power transformer and three-terminal voltage-stabilizing pipe.The basic thought of power module design is: using AC220V/ The step-down transformer of ACl2V obtains the 12V voltage of an exchange.Then alternating current is become by single phase bridge type rectifier circu After DC current is filtered using filter capacitor, after being connected to three-terminal voltage-stabilizing pipe 7808, output is stable direct current 8V electricity Pressure.

Physical circuit as shown in Fig. 2, although sine wave can be transformed into more smooth DC voltage by current rectifying and wave filtering circuit, But on the one hand since average voltage depends on transformer secondary voltage effective value, so when voltage ripple of power network, output Average voltage will generate corresponding fluctuation therewith；On the other hand due to the presence of current rectifying and wave filtering circuit internal resistance, when load changes When, the voltage in internal resistance will change, and then output voltage average value also generates opposite variation therewith.Therefore, rectification filter Wave circuit output voltage can be fluctuated with the fluctuation of network voltage.Change with the variation of load resistance, it is good in order to obtain Good DC voltage, it is necessary to take pressure stabilizing measure.It joined three terminal integrated voltage stabilizer LM7808 in a power to carry out surely Pressure.

Three-terminal voltage-stabilizing pipe refers to the integrated circuit of only three pins output, forms pressure stabilizing with 78 series three-terminal voltage-stabilizing IC Peripheral cell needed for power supply is few, there are also overcurrent, overheat and the protection circuit for adjusting pipe inside circuit, use it is reliable, It is convenient and cheap.The minimum input/output voltage difference of general three end integrated stable voltage circuit is about 2V, otherwise cannot be defeated Stable voltage out.Generally voltage difference should be made to be maintained at 4~5V, i.e., through transformer transformation, thyristor rectifier, after capacitor filtering Voltage should than pressure stabilizing be worth it is higher.Because circuit required voltage is 8V, and the voltage exported through transformer and fairing is 12V or so, therefore IC7808 type three-terminal voltage-stabilizing pipe is selected in the design, exports the burning voltage of 8V.

Two, with the sensor circuit designs of temperature compensation function:

Physical circuit as shown in figure 3, sensor circuit designs basic thought: circuit by three-terminal voltage-stabilizing pipe IC7808 it is defeated The constant voltage of 8V out supplies the heater circuit and detection circuit of sensor.Heater circuit needs the voltage of 5V could normal work Make, so a resistance of connecting on the heater circuit of sensor enables heater circuit to obtain the normal working voltage of 5V.Inspection Slowdown monitoring circuit is made of gas sensor TGS813, R1 and slide rheostat R1, and output voltage enters the same mutually defeated of voltage comparator Enter end, it is the pressure drop output at R1 and RL resistance both ends.Imflammable gas is in contact with sensor and when concentration over-standard, detection The output voltage of circuit will be more than the reference voltage of setting, and at this moment comparator in-phase end exports high level, make subsequent three pole Pipe plays a role to drive loudspeaker and relay coil to work.

Gas sensor is many kinds of.Here gas sensor TGS813 used in ventilation device belongs to N-type semiconductor class Gas sensor, main component are stannic oxide sintered bodies.When absorbing and reducing gas (such as liquefied gas, natural gas, hydrogen Gas, carbon monoxide, organic solvent steam etc.) when, conductivity rises.When being restored in clean air, conductivity is restored.TGS Sensor is exactly to take out this conductivity variations in a manner of output voltage, to detect the concentration of gas.

TGS sensor great advantage is that the service life is long, the sensory characteristic of TGS sensor only with the temperature and humidity variation in the four seasons and In cyclically-varying, there is no the trend being monotonically changed, illustrate that SnO2 semiconductor gas sensor has the extremely long service life.Because of design It is to be directed to household imflammable gas, therefore the TGS813 type gas sensor for natural gas, liquefied gas is selected to carry out gas Monitoring.The major parameter of TGS813 gas sensor: heating voltage is DC/AC (5V soil is O.2V), 537 DEG C of ignition temperature, is exploded The limit is 5%~15%, and temperature is 200 DEG C < T≤300 DEG C.The Warning alarm concentration of sensor settings should be LEL (under explosion Limit) 10%, danger warning concentration should be the 20% of LEL (lower explosion limit), and the explosion pole of TGS813 type gas sensor Limit is 5% (percentage in air), that is, 50000ppm, therefore warning concentration should be 5000~10000ppm.

Influence in order to compensate for temperature and humidity to sensor characteristics, while in order to obtain higher precision, therefore use heat Quick resistance or moisture sensor compensate circuit.

Three, compare and Design of Amplification Circuit:

The basic circuit diagram for comparing amplification is as shown in Figure 4.Signal compares the effect of amplifying circuit: when gas concentration is exceeded When, sensor will export the voltage signal bigger than setting voltage.The signal positive output after over-voltage comparator, then exists It is amplified by amplifying triode, to there is enough electric currents to remove driving relay coil and audio alerting unit.

Four, alarm and fan control circuitry design:

Ventilation device circuit of alarming is as shown in Figure 5.Warning circuit is one of important component of system.It is required that design Warning device can continuous alarm, therefore can not directly connect buzzer and loudspeaker device in circuit, it is necessary to be connected in circuit The device of pulse signal can be continuously generated.Multivibrator is a kind of self-excited oscillator, upon power-up, is not needed outer Add trigger signal, rectangular pulse just can be automatically generated, due to higher harmonic components rich in rectangular wave, so habit It is upper that square-wave oscillator is called multivibrator again.

555 timers are a kind of multiduty DA combination integrated circuits, using it can pole conveniently constitute multi-harmonic-oscillations The devices such as device, Schmidt trigger.Its using flexible, conveniently, thus 555 timers the generation and transformation of waveform, measurement with Many fields such as control are all widely used.Therefore the multivibrator that design alternative NE555 is constituted is believed as pulse Number source.The triode for playing amplification is connect in the output pin of NE555 multivibrator, so that it is sufficiently large to guarantee that circuit has Electric current go drive the speaker.Fan control circuitry is also one of component part of system.The fan control of the design uses The mode of relay control.Relay be it is a kind of according to the external world input certain signal (electrical or non-electrical) come in control circuit The automatic switchover electric appliance of electric current "on" and "off".It is mainly used to reflect various control signals, and contact is ordinarily connected to control electricity Lu Zhong.

The above is only the preferred embodiment of the present invention, is not intended to limit the utility model, all practical at this Within novel spirit and principle, any modification, equivalent replacement, improvement and so on should be included in the guarantor of the utility model Within the scope of shield.

Claims (1)

1. a kind of detection system of imflammable gas, it is characterised in that: including sequentially connected power circuit, voltage regulator circuit, biography Sensor, comparison circuit, amplifying circuit, the amplifying circuit are connect with the fan control and warning circuit being connected in parallel respectively, institute It states sensor and is provided with setting potential circuit connected in parallel；The power circuit provides after step-down transformer to voltage regulator circuit 12V DC power supply；The voltage regulator circuit is three terminal integrated voltage stabilizer LN7808；The sensor is gas sensor TGS813, The sensor parallel is provided with thermistor or humistor compensates circuit, the comparison circuit and amplifying circuit For concatenated voltage comparator and amplifying triode.