JPS6327279Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a gas leak signal converter.

A constant first voltage is sent to the gas leak detector during normal operation (normal times), a second voltage different from the first voltage is sent when a gas leak is detected, and no voltage is sent when there is a problem such as an unplugged outlet. There are two types of sensors: one type that terminates the gas signal line with a fixed terminating resistor during normal times, and when a gas leak is detected, the terminating resistor is connected by a contact, and in the event of a problem, the above contact is turned off. .

When the different types of sensors mentioned above are mixed,
Since these signals must be monitored by connecting each to a dedicated receiver, it is extremely wasteful and the configuration of the monitoring system becomes complicated.

An object of the present invention is to provide a gas leak signal converter that converts gas leak signals of different signal types into other types of signals, and to enable the coexistence of different types of gas leak detectors.

The converter of the present invention normally terminates the gas signal line with a constant terminating resistor, and when a gas leak is detected, the terminating resistor is disconnected by a contact, and in the event of trouble, the gas leak detector turns off the contact. a delay circuit connected to a power supply through a line and a current supply resistor to delay the potential of the gas signal line and input it to the first and second comparators; and when the output voltage of the delay circuit is higher than the first comparison voltage. A window comparator is configured of a first comparator that outputs a high level, a second comparator that outputs a high level when the output voltage of the delay circuit is lower than a second comparison voltage, and a window comparator that responds to the disconnection of the gas signal line. a gas leak determining circuit that determines that there is a gas leak when the output pulses of the pulse generating circuit exceed a certain number;
A signal that normally outputs a constant first voltage, outputs a second voltage different from the first voltage in response to the output of the gas leak determination circuit, and outputs no voltage in response to the output of the window comparator. It is characterized by comprising a conversion circuit.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention. In other words, a built-in power supply or a power supply that converts the voltage sent through the line from the receiver side to a constant voltage.
VCC is connected to a gas signal line L through a resistor R ₂ , a diode D ₁ and a resistor R ₁ , and a gas sensor (not shown) is connected between the gas signal line L and a common line (ground line) C. During normal operation, the gas sensor terminates the gas signal line L and the common line C with a constant resistance, and when gas leakage is detected, the resistance is interrupted by a contact point. In addition, the sensor turns off the contacts in the event of a problem such as an unplugged outlet. The resistance _R1 is set by the sum of the resistance of the gas signal line L and the terminating resistance of the sensor so that the voltage at point A (on the gas signal line side of the diode _D1 ) during normal operation becomes appropriate.

Capacitor C 3 is charged from the power supply side ₍ point B) of diode D ₁ through resistor R ₆ , and capacitor C ₃
The voltage is input to the + input of the first comparator 1 and the - input of the second comparator 2. The resistor R ₆ and capacitor C ₃ constitute a delay circuit. Note that resistor R ₆ is connected to diode D ₃ and resistor R ₅
The series-connected circuits are connected in parallel, and the time constants during charging and discharging are different. The first comparison voltage VR ₁ is input to the negative terminal of the comparator 1, and the second comparison voltage VR ₂ is input to the positive terminal of the comparator 2. The second comparison voltage VR ₂ is sufficiently higher than the voltage at point B under normal conditions and slightly lower than the power supply voltage VCC,
The first comparison voltage VR ₁ has a value slightly lower than the voltage at point B in normal conditions. Therefore, when the sensor is in trouble, the voltage at point B rises to near the power supply voltage, and the output of the second comparator 2 becomes low level. Further, when the gas signal line L is short-circuited, the voltage at point B decreases and the output of the first comparator 1 becomes low level. The outputs of the first and second comparators are wired OR connected to form a window comparator. That is, the window comparator normally outputs a high level, and outputs a low level when there is a problem such as an open or short circuit in the gas signal line or sensor. The output terminal is connected to the power supply VCC through a resistor _R9 , and is at a high level under normal conditions.

On the other hand, the above point A (gas signal line side of diode D ₁ ) is input to the + terminal of the third comparator 3, and the power supply side of diode D ₁ (point B) is connected to the - terminal of the above comparator 3 through resistor R ₄ . Connecting.
The - terminal is grounded by capacitor _C2 . Furthermore, a series connection circuit of a diode D ₂ and a resistor R ₃ is connected in parallel to the resistor R ₄ . In normal times, the voltage at the - terminal is higher than the voltage at the + terminal by a forward bias voltage (approximately 0.5V) generated by the current flowing through the diode _D1 , so the output of the third comparator is at a low level. However, when the gas sensor opens the contact, the voltage at point A, and therefore the + terminal of comparator 3, immediately rises to the power supply voltage VCC as shown by the solid line in Figure 2a.
The voltage at the − terminal rises with a slight delay, as shown by the dotted line in the figure. The next time the sensor closes its contacts,
Since the voltage at the + terminal drops immediately and the voltage at the - terminal drops with a delay, comparator 3 eventually falls as indicated by b in the figure.
As shown in , the voltage at the + terminal remains high only during the period when the voltage at the - terminal is higher than that at the - terminal, and a pulse is output. The pulse is output each time the sensor contact is made and made. That is, the comparator 3 constitutes a pulse generating circuit that generates pulses in response to the disconnection of the gas signal line.

The output of the comparator 3 is connected to the power supply VCC through a resistor R ₇ and to the capacitor C ₄ and the - terminal of the fourth comparator 4 through a resistor R ₈ . The other end of capacitor _C4 is grounded.
Furthermore, a diode _D4 is connected in parallel to the resistor _R8 . A diode D ₄ , a capacitor C ₄ , etc. constitute an integrating circuit. That is, the output pulse of comparator 3 is integrated into capacitor C ₄ via diode D ₄ . The pulse off period is resistor _R8
However, since the resistor R ₈ has a high resistance, the charging voltage of the capacitor C ₄ increases with each pulse, as shown in Fig. 2c, and by 3 to 4 pulses the comparison voltage increases. Exceeds VR ₃ . At this time, the output of the fourth comparator 4 becomes low level.

In this embodiment, the integration circuit and the fourth comparator constitute a gas leak determination circuit. The gas leak determination circuit may also use a counter that counts the output pulses of the pulse generating circuit and determines a gas leak based on a certain count value.
Further, the pulse generation circuit can also be configured with a multivibrator that is triggered by a pulse obtained by differentiating a voltage change of a gas signal line, for example.
In this case diode _D1 is not required. Alternatively, if both ends of _the resistor _R6 are connected to the +-terminals of the comparator ₃ , the comparator It is also possible to output pulses from 3. In this case, the resistance
R ₃ , R ₄ capacitor C ₂ etc. are not required. As the sensor contacts are disconnected, the voltage of capacitor _C3 is charged and discharged as shown in the curve VC in Figure 3.
The voltage across resistor R ₆ inverts in response to contact breaking, allowing the comparator to be inverted.

On the other hand, as _shown in FIG.
The voltage will never be higher than the comparison voltage. In other words, depending on the sensor contact disconnection (gas leak signal), the first
and the second comparator is not inverted. and,
When the contact of the sensor is turned off (trouble signal), the voltage of capacitor C ₃ increases according to the time constant of R ₆ C ₃ as shown in vc′ in the same figure, and the second comparison voltage VR ₂ When it exceeds the threshold, the output of the second comparator 2 becomes low level. In addition, for troubles such as a short circuit in the gas signal line L, use a capacitor.
The voltage of C ₃ decreases according to the time constant of R ₅ C ₃ as shown by vc'' in the figure, and when it becomes lower than the first comparison voltage VR ₁ , the output of the first comparator 1 becomes low level.

On the other hand, the signal conversion circuit connects the resistor _R17 from the power supply VCC
and a Zener diode ZD through a resistor _R18 , the other end of the Zener diode _Z2 is connected to the collector of the transistor _T1 , and the emitter of the transistor _T1 is grounded. The output of the window comparator is connected to the base of the transistor _T1 through a resistor _R10 . In normal times, the power supply
Transistor T ₁ from VCC through resistors R ₉ and R ₁₀
A positive potential is applied to the base of , the transistor T ₁ is in the on state, and the Zener diode ZD
gives, for example, 6V to the base of transistor _T5 . The collector of the transistor T ₅ is connected with the resistor R ₁₈
Connected to the junction of R ₁₇ , the emitter is a diode
Connected to alarm wire GL through D ₉ . That is, the transistor _T5 sends an output of about 6V to the alarm line GL by the emitter floor output. Note that diode _D8 is a reverse voltage prevention diode. Also, connect the junction of the Zener diode ZD and the resistor R ₁₈ to the collector of the transistor T ₃ ,
The emitter of the transistor T ₃ is grounded, and the base is grounded by a parallel circuit of a capacitor C ₅ and a resistor ₁₆ , and is also connected through a resistor ₁₅ to the collector of the transistor T ₄ . The emitter of the transistor _T4 is connected to the power supply VCC and to one end of the base resistor _R17 . When an overcurrent flows through resistor ₁₇ for some reason, transistor _T4 turns on, which turns on transistor _T3 , which sets the base of transistor _T5 to low level and issues a trouble signal (OV) as an alarm. Send to line GL. Also,
The power supply VCC is connected to the collector of the transistor T ₂ through the resistor R ₁₄ , and the emitter of the transistor T ₂ is grounded. The collector of transistor T ₂ is connected through a diode D ₆ to the output of the fourth comparator 4 and through a diode D ₇ to the collector of transistor T ₄ . Transistor _T2
The base of is connected to the output of the window comparator through a resistor _R12 and is also grounded by a resistor _R13 . Further, the output of the window comparator and the output of the fourth comparator are connected by a diode _D5 . In this example,
The resistor _R18 and the Zener diode ZD constitute a constant voltage circuit (6V), the transistor _T1 constitutes the first switching circuit, and the transistor _T3 constitutes the second switching circuit.
It constitutes a switching circuit. Then, the first switching circuit, that is, the transistor T ₁
is always on and turns off when a problem occurs. Further, when the output of the fourth comparator 4 becomes low level when a gas leaks, the base becomes low level through the diode _D5 and is turned off. In addition, the second
The switching circuit of transistor _T3 is
When the output of the fourth comparator 4 becomes low level during a gas leak, the collector of the transistor _T2 becomes low level through the diode _D6 , and therefore the base of the transistor _T3 also becomes low level, turning it off. Therefore, when gas leaks, transistor _T3 is turned off and transistor _T1 is also turned off, so the base potential of transistor _T5 rises,
A power supply voltage (second voltage) of approximately 12V is output from the emitter. In case of trouble, that is, when the output of the window comparator becomes low level, transistor _T2 is turned off and its collector becomes high level, so transistor _T3
is turned on, the base of transistor _T5 is set to low level, and the output to the alarm line GL is also set to low level (0V). However, even in times of trouble,
When a gas leak occurs at the same time, the collector of transistor T ₂ is forced to a low level via diode D ₆ , so transistor T ₃ is off, while transistor T ₁ is also off, so transistor _T5 sends out a high level of approximately 12V. In other words, priority is given to gas leakage.

To summarize the above, when the gas sensor is operating normally, the first voltage of approximately 6V is sent to the alarm line GL, and when the gas sensor detects a gas leak and the contact is interrupted, the alarm line A second voltage of about 12V is output to GL, and a signal conversion is performed in which a low level is sent to the alarm line GL when the gas sensor detects a trouble and opens the contact, or when the gas signal line is disconnected or shorted. . Therefore, by using this gas leak signal converter, different types of gas leak signals can be easily converted into other types of gas leak signals, etc.
This has the effect that different types of gas leak detectors can be used together.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an embodiment of the present invention, and Figures 2a, b, and c respectively show the input voltage of the third comparator, the output voltage of the comparator, and the voltage of the integrating circuit in the above embodiment. Waveform Diagram FIG. 3 is a waveform diagram showing the output voltage of the delay circuit in the above embodiment. In the figure, 1 to 4...first to fourth comparators, _R1 to _R18 ...resistors, _D1 to _D9 ...diodes, _C2 to _C6 ...capacitors, _T1 to _T5 ... Transistor, ZD...Zener diode, VR ₁ ~
VR ₃ ...First to third comparison voltages.

Claims (1)

[Claims for Utility Model Registration] (1) Gas leak detection in which the gas signal line is normally terminated with a constant terminating resistor, and when a gas leak is detected, the terminating resistor is disconnected by a contact, and in the event of a problem, the above contact is turned off. a delay circuit that connects the device to a power source through a gas signal line and a current supply resistor, delays the potential of the gas signal line and inputs it to the first and second comparators, and the output voltage of the delay circuit is a first comparison voltage. a first comparator that outputs a high level when the voltage is higher than the second comparison voltage; and a second comparator that outputs a high level when the output voltage of the delay circuit is lower than the second comparison voltage; a pulse generation circuit that generates pulses in response to the intermittence; a gas leak determination circuit that determines that there is a gas leak when the output pulses of the pulse generation circuit exceed a certain number; and a gas leak determination circuit that normally outputs a constant first voltage;
It is characterized by comprising a signal conversion circuit that outputs a second voltage different from the first voltage in response to the output of the gas leak determination circuit, and outputs no voltage in response to the output of the window comparator. Gas leak signal converter. (2) Utility Model Registration The gas leak signal converter according to claim 1 is provided with a third comparator, and a diode is inserted in series between the current supply resistor and the gas signal line. The gas signal line side of the diode is connected to + of the third comparator.
terminal, the current supply resistor side of the diode is connected to the - terminal of the third comparator via a resistor, and the - terminal of the third comparator is grounded via a capacitor. The pulse generation circuit is characterized by comprising a comparator. (3) Utility model registration The gas leak signal converter according to claim 1 is provided with a third comparator, and a circuit including both ends of the resistor of the delay circuit is connected to both inputs of the third comparator. The pulse generating circuit is characterized by comprising the third comparator. (4) Scope of Utility Model Registration Claims In the gas leak signal converter according to any one of claims 1 to 3, the gas leak determination circuit includes an integrating circuit that integrates the output voltage of the pulse generating circuit; and a fourth comparator that compares the output voltage of the circuit with a constant comparison voltage. (5) Utility model registration Claims In the gas leak signal converter according to any one of claims 1 to 4, the signal conversion circuit includes a constant voltage circuit including a resistor and a Zener diode, and a constant voltage circuit connected in series with the Zener diode. a first switch circuit connected to the first switch circuit; and a second switch circuit connected in parallel to a series connection circuit of the Zener diode and the first switch circuit, the first switch circuit is always on. The second switch circuit is turned off by the output of the gas leak judgment circuit, and the second switch circuit is turned on by the output of the window comparator and turned off by the output of the gas leak judgment circuit.