Gas alarm emergency power supply

Abstract

The emergency power supply of the gas alarm is composed of a battery charging circuit, a battery charging voltage monitoring circuit, a battery charging termination trigger circuit, a battery discharging circuit and a battery discharging termination circuit. The battery's charging, discharging, voltage monitoring, and charging and discharging termination are controlled through various battery circuits, so that the gas alarm power supply can work normally when the mains power fails, and has high stability.

Description

Technical Field

[0001] The utility model relates to the technical field of gas safety, in particular to an emergency power supply for a gas alarm. Background Art

[0002] The existing household gas alarm relies on the 220V AC power supply of the city grid. When the city grid unexpectedly loses power, the alarm will fail and there will be a blind spot in monitoring. It is necessary to provide a safe emergency power supply for the gas alarm. Summary of the invention

[0003] The technical problem to be solved by the utility model is to provide an emergency power supply for a gas alarm, so as to solve the failure problem of the power supply of the gas alarm.

[0004] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0005] The emergency power supply of the gas alarm consists of a battery charging circuit, a battery charging voltage monitoring circuit, a battery charging termination trigger circuit, a battery discharging circuit and a battery discharging termination circuit.

[0006] The above-mentioned battery charging circuit is composed of a linear transformer T, rectifier diodes VD1~VD4, a diode VD5, a current limiting resistor R19, a one-way thyristor CR, and a diode VD7. The AC power of the linear transformer T is rectified into DC power by the rectifier diodes VD1~VD4 and then charged to the battery through the diode VD5, the current limiting resistor R19, the one-way thyristor CR and the diode VD7.

[0007] The above-mentioned battery charging voltage monitoring circuit is composed of an overheat protection resettable fuse PTC, RE2 moving contact, R14, R10, R13, the non-inverting input terminal of the operational amplifier IC1A, VD5, R18, R4, a Zener diode ZD1 and the inverting input terminal of IC1A. The positive electrode of the battery is connected to the overheat protection resettable fuse PTC and then connected to the non-inverting input terminal of IC1A via the RE2 moving contact, R14 and R10. The DC positive voltage Vcc is connected to the inverting input terminal of IC1A via VD5, R18, R4 and the Zener diode ZD1.

[0008] The above-mentioned battery charging termination trigger circuit is connected from the output end of IC1A to the base b of the NPN transistor Q3 through the anti-reverse diode ZD4 and R3, the collector c of the transistor Q3 is connected to the unidirectional thyristor CR through the diode ZD2, and the emitter e of the transistor Q3 is connected to the DC negative pole or the ground.

[0009] The above-mentioned battery discharge circuit is composed of PTC, bistable switch SW, relay RE2 break contact, relay RE1 make contact. The positive electrode of the battery is connected to pin 1 of the voltage regulator chip IC2 through PTC, bistable switch SW, relay RE2 break contact, relay RE1 make contact.

[0010] The above-mentioned battery discharge termination circuit is composed of a resistor R5, a diode VD11, a voltage stabilizing diode ZD3, and a transistor Q1. Pin 1 of the voltage stabilizing chip IC2 is connected to the base b of the transistor Q1 through the resistor R5, the diode VD11, and the voltage stabilizing diode ZD3. The collector c of the transistor Q1 is connected to the coil of the relay RE1. The other end of the coil of the relay RE1 is connected to the bistable switch SW. The emitter e of the transistor Q1 is connected to the DC negative pole or the ground.

[0011] The utility model provides a gas alarm emergency power supply, which realizes the control of charging, discharging, voltage monitoring, and charging and discharging termination of the battery through multiple circuits of the battery, so that the gas alarm power supply can work normally when the city power fails, and has high stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0013] Figure 1 This is a schematic diagram of the circuit connection structure of the utility model;

[0014] Figure 2 This is a schematic diagram of the battery charging circuit mechanism;

[0015] Figure 3 This is a schematic diagram of the battery charging voltage monitoring circuit structure;

[0016] Figure 4 This is a schematic diagram of the battery charging termination trigger circuit structure;

[0017] Figure 5 It is the battery discharge circuit;

[0018] Figure 6 It is the battery discharge termination circuit. DETAILED DESCRIPTION

[0019] The emergency power supply of the gas alarm consists of a battery charging circuit, a battery charging voltage monitoring circuit, a battery charging termination trigger circuit, a battery discharging circuit and a battery discharging termination circuit.

[0020] The above-mentioned battery charging circuit is composed of a linear transformer T, rectifier diodes VD1~VD4, a diode VD5, a current limiting resistor R19, a one-way thyristor CR, and a diode VD7. The AC power of the linear transformer T is rectified into DC power by the rectifier diodes VD1~VD4 and then charged to the battery through the diode VD5, the current limiting resistor R19, the one-way thyristor CR and the diode VD7.

[0021] The above-mentioned battery charging voltage monitoring circuit is composed of an overheat protection resettable fuse PTC, RE2 moving contact, R14, R10, R13, the non-inverting input terminal of the operational amplifier IC1A, VD5, R18, R4, a Zener diode ZD1 and the inverting input terminal of IC1A. The positive electrode of the battery is connected to the overheat protection resettable fuse PTC and then connected to the non-inverting input terminal of IC1A via the RE2 moving contact, R14 and R10. The DC positive voltage Vcc is connected to the inverting input terminal of IC1A via VD5, R18, R4 and the Zener diode ZD1.

[0022] The above-mentioned battery charging termination trigger circuit is connected from the output end of IC1A to the base b of the NPN transistor Q3 through the anti-reverse diode ZD4 and R3, the collector c of the transistor Q3 is connected to the unidirectional thyristor CR through the diode ZD2, and the emitter e of the transistor Q3 is connected to the DC negative pole or the ground.

[0023] The above-mentioned battery discharge circuit is composed of PTC, bistable switch SW, relay RE2 break contact, relay RE1 make contact. The positive electrode of the battery is connected to pin 1 of the voltage regulator chip IC2 through PTC, bistable switch SW, relay RE2 break contact, relay RE1 make contact.

[0024] The above-mentioned battery discharge termination circuit is composed of a resistor R5, a diode VD11, a voltage stabilizing diode ZD3, and a transistor Q1. Pin 1 of the voltage stabilizing chip IC2 is connected to the base b of the transistor Q1 through the resistor R5, the diode VD11, and the voltage stabilizing diode ZD3. The collector c of the transistor Q1 is connected to the coil of the relay RE1. The other end of the coil of the relay RE1 is connected to the bistable switch SW. The emitter e of the transistor Q1 is connected to the DC negative pole or the ground.

[0025] Example:

[0026] 1. Battery charging circuit; this circuit is mainly composed of linear transformer T, rectifier diodes VD1~VD4, diode VD5, current limiting resistor R19, unidirectional thyristor CR, diode VD7, such as Figure 2After the city power is connected, the 220V AC is converted into 14V AC by T, and then rectified into pulsating DC with AC components by VD1~VD4, and then filtered into smooth DC of about 16V by electrolytic capacitor C4. One path of the DC is connected to the anode of CR after being stepped down by resistor R19, and the other path is sent to the control electrode of CR after being stepped down by R18; CR is turned on, and the voltage of about 14.68V output by the cathode of CR generates a voltage drop of about 0.7V on VD7 and is connected to the positive electrode of the battery, and the city power starts to charge the battery.

[0027] The direct current through R19 also supplies power to the coil of relay RE2 through diode ZD01. After RE2 is energized, its normally closed contacts close, which supplies power to the alarm on the one hand and connects the battery terminal voltage sampling circuit composed of R14, R10 and R13 in series on the other hand.

[0028] 2. Battery charging voltage monitoring circuit; such as Figure 3 The circuit mainly consists of overheat protection self-recovery fuse PTC, RE2 moving contact, R14, R10, R13, operational amplifier IC1A's non-inverting input terminal, VD5, R18, R4, voltage regulator diode ZD1, and IC1A's inverting input terminal. After the mains is connected, the DC 16V power supply after step-down rectification is connected to the cathode of voltage regulator diode ZD1 (Zener Diod) through R18 and R4 current limiting, resulting in IC1A's inverting input terminal being clamped at a potential of about 3V, the reverse working voltage of ZD1. In other words, IC1A's inverting input terminal is a constant voltage, fixed potential; while its non-inverting input terminal's potential is rising with the voltage of the battery's positive electrode.

[0029] 3. Battery charging termination trigger circuit. As charging continues, when the potential of IC1A's non-inverting input terminal exceeds its inverting input terminal potential by 3.1657V (the battery terminal voltage reaches 13.9~14.0573V), the voltage comparator formed by IC1A flips, and its output terminal outputs a high level close to the working power supply of the integrated circuit. This high potential of about 14V breaks down the Zener diode ZD4 (its reverse breakdown voltage is about 11.86V). After ZD4 breaks down, the base b of the NPN transistor Q3 becomes a high level, Q3 is turned on, and the potential between its collector c and emitter e is almost equal, then the positive electrode of the Zener diode ZD2 is pulled to zero potential. At this time, the negative electrode of ZD2 is above a high potential of about 15V, ZD2 is in a reverse breakdown state, and the potential of its negative electrode is clamped below a potential of 8.46V, causing the control electrode of CR to be reverse biased (a negative voltage relative to the on state), CR is cut off, causing the battery charging circuit to be cut off, and charging is terminated, such as Figure 4 .

[0030] The equivalent principle of unidirectional thyristor is as follows Figure 1 As shown in the shadow in the lower right corner: when the AC power is connected, a high potential of 15.48V is added to the anode of CR, that is, P1=15.48, then the PN junction composed of P1N1 is in the on state, and the potential of N1 is about 14.48V (the forward voltage drop of the PN junction is about 0.7V). When P2 is connected to a high potential of 14.35V, the PN junction P2N2 is also in a forward biased state. After amplification by a single tube, it is sent to the base of the NPN transistor to form a positive feedback. As a result of the positive feedback cycle, the current of the two tubes increases sharply, and the thyristor is saturated and turned on; the potential between A and K is almost the same, about 14.68V. The reverse breakdown of ZD2 causes the potential of the G pole to be pulled down to 8.46V, then the potential of N2 is higher than that of P2, the PN junction P2N2 is in a reverse biased state, the NPN transistor is cut off, and the thyristor is turned off.

[0031] 4. Battery charging restart mode. After charging is completed, the standby power supply of the alarm is disconnected from the mains and taken over by the battery; the battery self-discharge begins, plus the static power consumption of the alarm, the battery charging voltage monitoring circuit at this time takes on the task of discharging voltage monitoring. When the voltage of the third pin of IC1 is lower than 2.881V (the battery terminal voltage is lower than 12.9~13.0345V), its first pin outputs a low level, ZD4, Q3, and ZDW are all cut off, and the control electrode of the thyristor CR is connected to the forward bias voltage again, it is turned on, and the battery enters the charging mode again.

[0032] Exit mechanism of charging and discharging dead cycle: to prevent the dead cycle that when the inverting input terminal of IC1A is at a constant potential of 3.1657V, the charging stops when the potential of its non-inverting input terminal is greater than this potential, and starts charging again immediately when it is less than this potential. Figure 2 The potential of the "T" point in .2 can jump from 15.4V to 8.5V. When the T point is 8.5V, the current flowing through ZD1 decreases to 1.7mA, and its regulated voltage value decreases to 2.881V; when the T point returns to 15.4V, the current flowing through ZD1 increases to 4mA, and its regulated voltage value increases to 3.1657V; therefore, the lower limit of the reference voltage is 2.881V and the upper limit is 3.166V, thereby increasing the bandwidth of the sampling voltage.

[0033] 5.1 Battery discharge circuit; Figure 5 The main discharge circuit is mainly composed of PTC, bistable switch SW, relay RE2 break contact, and relay RE1 make contact. Its main function is to power the household gas alarm.

[0034] Resistors R8, R11 and transistor Q2 form a mains power failure detection circuit. When the grid has power, T steps down the voltage, and the full-wave rectified DC power is divided by R8 and R11 and added to the base of NPN transistor Q2. Q2 is turned on, the base potential of Q1 is zero, and the coil of relay RE1 is de-energized. When the grid fails, the base potential of Q2 is low, Q2 is cut off and its collector is high, then Q1 is turned on, the coil of RE1 is energized, and the positive electrode of the battery discharges to the alarm through the PTC, SW, and RE1 moving contacts.

[0035] 5.2 Battery discharge termination circuit; if Figure 6 The main function of this circuit is to monitor whether the terminal voltage of the battery drops to the allowable threshold during the discharge process. It is mainly composed of resistor R5, diode VD11, Zener diode ZD3 and transistor Q1.

[0036] As the battery discharges, its terminal voltage continues to decrease. When the negative electrode voltage of ZD3 drops to its reverse breakdown voltage of 9.22V, ZD3 is turned off, the base of Q1 loses power, Q1 is cut off, the RE1 coil loses power, and the discharge ends.

[0037] 3 Setting the function of the bistable switch SW

[0038] During the factory production test phase, once the mains power is lost, the battery will be triggered to enter the discharge state. To prevent the battery from being exhausted, the SW can be cut off to disconnect the battery discharge circuit during the storage phase of the power supply.

Claims

1. Gas alarm emergency power supply, characterized in that: The emergency power supply circuit is composed of a battery charging circuit, a battery charging voltage monitoring circuit, a battery charging termination trigger circuit, a battery discharging circuit and a battery discharging termination circuit; The battery charging circuit is composed of a linear transformer T, rectifier diodes VD1-VD4, a diode VD5, a current limiting resistor R19, a unidirectional thyristor CR, and a diode VD7. The alternating current of the linear transformer T is rectified into direct current by rectifier diodes VD1-VD4 and then charged into the battery by diode VD5, a current limiting resistor R19, a unidirectional thyristor CR, and a diode VD7. The battery charging voltage monitoring circuit is composed of an overheat protection resettable fuse PTC, a RE2 normally closed contact, R14, R10, R13, a non-inverting input terminal of an operational amplifier IC1A, VD5, R18, R4, a voltage stabilizing diode ZD1 and an inverting input terminal of IC1A. The positive electrode of the battery is connected to the overheat protection resettable fuse PTC and then connected to the non-inverting input terminal of IC1A via the RE2 normally closed contact, R14 and R10. The DC positive voltage Vcc is connected to the inverting input terminal of IC1A via VD5, R18, R4 and the voltage stabilizing diode ZD1. The battery charging termination trigger circuit is connected by the output end of IC1A to the base b of NPN transistor Q3 through anti-reverse diode ZD4 and R3, the collector c of transistor Q3 is connected to the unidirectional thyristor CR through diode ZD2, and the emitter e of transistor Q3 is connected to the DC negative pole or ground; The battery discharge circuit is composed of PTC, bistable switch SW, relay RE2 break contact, relay RE1 make contact, and the positive electrode of the battery is connected to pin 1 of the voltage stabilizing chip IC2 through PTC, bistable switch SW, relay RE2 break contact, relay RE1 make contact; The battery discharge termination circuit is composed of a resistor R5, a diode VD11, a voltage stabilizing diode ZD3, and a transistor Q1. Pin 1 of the voltage stabilizing chip IC2 is connected to the base b of the transistor Q1 through the resistor R5, the diode VD11, and the voltage stabilizing diode ZD3. The collector c of the transistor Q1 is connected to the coil of the relay RE1. The other end of the coil of the relay RE1 is connected to the bistable switch SW. The emitter e of the transistor Q1 is connected to the DC negative pole or the ground.

Images