JP2002214176A - Gas detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas detector capable of precisely detecting gas concentration. SOLUTION: In this gas detector, the resistance value of a gas sensor 9a1 and the resistance value of a thermistor 9a3 are calculated from two detection signals from a gas sensor part 9a, whereby the ambient temperature is outputted, and a precise gas sensor resistance value taking temperature dependency into consideration is calculated and outputted. Further, the precise gas concentration can be also displayed. When this gas detector is applied to an air conditioner or the like, the blowing fan and air cleaning unit of the air conditioner are controlled on the basis of the precise gas concentration detected by the gas detector, whereby a comfortable interior environment can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas detection device used for an air purifier or an air conditioner, and more particularly to a gas detection device having improved detection accuracy.

[0002]

2. Description of the Related Art A gas detecting device 9 includes a gas sensor 9a for outputting a gas detection signal corresponding to a gas concentration, a temperature sensor 9c for outputting a temperature detection signal corresponding to an ambient temperature, and
A correction means 9b for correcting a gas detection signal output from the gas sensor section 9a with a temperature detection signal from the temperature sensor 9c. As shown in FIG. 6, the conventional gas sensor unit 9a includes a gas sensor 9a1 having a resistance value that varies according to a gas concentration, and a fixed resistance applied to the gas sensor 9a1.
It was connected as a2. And this gas sensor unit 9
The correction means 9b for correcting the gas concentration from the temperature sensor 9c calculates the resistance value of the gas sensor 9a1 by measuring the voltage across the load resistor 9a2, and converts the resistance value to the gas concentration. Output.
By the way, the resistance value R1 of the gas sensor 9a1 used in the gas sensor section 9a varies depending on the gas concentration G and varies under the influence of the ambient temperature T. Therefore, a heating means 9d is provided inside, and the temperature T Is configured to be constant. However, irrespective of the heating means 9d, when the ambient temperature T changes, the resistance value R1 of the gas sensor 9a1 also changes, so that there is a problem that an accurate concentration cannot be detected. In the air conditioner using the gas detection device 9, as shown in FIG. 1, a heat exchanger 5 and a blower 7 are arranged in an air passage 4 connecting an inlet 2 and an outlet 3 of a main body 1. , An air purifier 6 on the windward side of the heat exchanger 5
And an air filter 2a is arranged in the suction port 2, and a room temperature sensor 8 detects the room temperature,
The gas detector 9 detects the gas concentration in the room, and determines the operation mode corresponding to the room temperature and the gas concentration. The gas detecting device 9 uses the room temperature sensor 8 as the temperature sensor 9c, and corrects the gas concentration in accordance with the room temperature detected by the room temperature sensor 8. However, since the temperature sensor 9c is formed separately from the gas sensor 9a constituting the gas detection device 9 and is installed at a place separated from each other, the gas concentration is corrected according to the room temperature detected by the temperature sensor 9c. However, there is a problem that the gas concentration cannot be corrected to a correct value.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a gas detector capable of detecting a gas concentration with high accuracy.

[0004]

According to the present invention, there is provided a gas sensor for outputting a gas detection signal corresponding to a gas concentration, a temperature sensor for outputting a temperature detection signal corresponding to an ambient temperature. In a gas detection device comprising a correction unit that corrects a gas detection signal output from the gas sensor unit with a temperature detection signal from the temperature sensor,
The temperature sensor is a gas detection device provided integrally with the gas sensor unit.

The gas sensor section comprises a gas sensor having a resistance value which varies according to the gas concentration, and a series circuit of a thermistor serving as a load resistance of the gas sensor and a fixed resistor, and a connection point between the gas sensor and the load resistance. And a gas detection device having a connection point between the thermistor and the fixed resistor as an output terminal.

[0006] The resistance value of the gas sensor and the resistance value of the load resistance are made substantially the same value, and the temperature characteristic of the resistance value of the thermistor and the temperature characteristic of the resistance value of the gas sensor are made substantially the same. Is an improved gas detection device.

The correction means is connected to the two output terminals, and calculates the resistance values of the gas sensor and the thermistor by measuring respective terminal voltages of the load resistance and the fixed resistance, and calculates the resistance value of the thermistor. Is converted to a temperature and output, and the resistance value of the gas sensor is corrected and output based on the ambient temperature.

The correction means has a conversion table for converting the corrected resistance value of the gas sensor into a gas concentration, and outputs the gas concentration converted by the conversion table.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a gas sensor, a gas detection device and an air conditioner according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a side sectional view showing an embodiment of an air conditioner using a gas detector according to the present invention, and FIG. 2 is a circuit diagram showing an embodiment of the gas detector according to the present invention.
FIG. 3 shows an embodiment of a temperature table of the gas detector according to the present invention, FIG. 4 shows an embodiment of a correction value table of the gas detector according to the present invention, and FIG. 5 shows a gas concentration table of the gas detector according to the present invention. 6 is a table showing one embodiment of the present invention. Figure 1
As shown in the figure, the air conditioner has a base 1a and a base 1a.
a heat exchanger 5 and a heat exchanger 5 in an air passage 4 connecting an inlet 2 provided on the front and upper surfaces of the main body 1 composed of a front panel 1b arranged on the front of the main body 1 and an outlet 3 provided on the lower part of the front. An air purifying unit 6 attached to the windward side of the air conditioner 5 and a blower 7 for blowing air conditioned by the air purifying unit 6 and the heat exchanger 5 to the outlet 3 are provided. An air filter 2a is provided in the suction port 2,
A room temperature sensor 8 and a gas detection device 9 are provided.
A display unit 20 for displaying gas concentration is provided on the front surface of the front panel 1b.

As shown in FIG. 2, the gas detector 9 includes a gas sensor 9a for outputting a detection signal for calculating a resistance value R1 and an ambient temperature T of the gas sensor 9a1,
A correction means 9b for calculating a resistance value R1 and an ambient temperature T of the gas sensor 9a1 based on a detection signal from the gas sensor section 9a and correcting the resistance value R1. As shown in FIG. 2, one side of the gas sensor section 9a is connected to the power supply side, and one side of a load resistor 9a2 is connected to the other side of the gas sensor 9a1 whose resistance value changes according to the gas concentration. The other side of 9a2 is grounded. The thermistor 9 is used as the load resistor 9a2.
A series circuit 9a5 of a3 and a fixed resistor 9a4 having a known resistance value R0 is connected. Then, the gas sensor 9a
1 and the connection point A between the load resistor 9a2 and the thermistor 9a3
A first voltage V1 and a second voltage V2 are output as detection signals of the gas sensor unit 9a from a connection point B between the first voltage V1 and the fixed resistor 9a4. The thermistor 9a3 has the same temperature characteristic as that of the gas sensor 9a1.
1 is corrected to be the same as the resistance value R1 of 1
The resistance value R2 of the load resistor 9a2 and the resistance value R1 of the gas sensor 9a1 are corrected so as to have the same value irrespective of the ambient temperature, so that the detection accuracy is improved.

The correcting means 9b comprises a CPU 10 having two A / D converters (analog / digital converters) 9b1 and 9b2. The storage unit 10a of the CPU 10 stores the known resistance value R0, the power supply voltage Vcc supplied to the gas sensor 9a1, and a temperature T corresponding to the resistance value R3 of the thermistor 9a3 as shown in FIG. A table Tt, a correction value table Rt indicating a correction value R1 of the resistance value R1 of the gas sensor 9a1 corresponding to the same temperature as shown in FIG. 4, and a resistance value R1 of the gas sensor 9a1 as shown in FIG. A gas concentration table Gt indicating the gas concentration G to be performed is stored.
A first voltage V1 and a second voltage V2, which are two detection signals output from the gas sensor unit 9a, are used for the two A signals.
The signals are input to the / D conversion units 9b1 and 9b2 and converted into digital signals. The known resistance value R0, the power supply voltage Vcc, and the digitally converted first voltage V1
And the second voltage V2, the resistance R of the thermistor 9a3
3. The resistance value R1 of the gas sensor 9a1 is calculated as follows. The current I flowing through the load resistor is: I = V2 / R0 Equation 1 The resistance value R3 of the thermistor 9a3 is R3 = (V1-V2) / I Equation 2 Equation 1 is substituted into Equation 2. R3 = (V1−V2) RO / V2 Equation 3 The resistance value R1 of the gas sensor 9a1 is R1 = (Vcc-V1) / I Equation 4 Substitute Equation 1 into Equation 4. R1 = (Vcc−V1) RO / V2 Equation 5

Next, the resistance R3 of the thermistor 9a3 calculated by the above equation 3 with reference to the temperature table Tt.
Is found. This temperature T may be used as an output of the room temperature sensor for controlling the air conditioner. next,
The correction value R1 of the resistance value R1 of the gas sensor 9a1 corresponding to the temperature T is obtained with reference to the correction value table Rt, and the correction value R1 of the resistance value R1 is added to the resistance value R1 to correct the gas sensor 9a1. Is determined. That is, the resistance value R1 'of the gas sensor 9a1 is obtained as R1' = R1 + R1... The gas concentration G is obtained by referring to the gas concentration table Gt with the corrected resistance value R1 'of the gas sensor 9a1 obtained in this way as R1. The gas concentration G is output from the output unit 9b4 and is displayed on the display unit 20.

The CPU 10 includes the blower 7
And a gas concentration setting means 10b for setting a gas concentration level G1 for starting the operation of the air purifying unit 6 and a gas concentration setting means 10b for setting the gas concentration level G2 for starting the operation of the air cleaning unit 6. If it exceeds, the blower driver 9b
6 starts the operation of the blower 7, and when it exceeds G2, the air purifier driving unit 9b7
Is controlled to start the operation.

In the above, the gas concentration G is determined from the corrected resistance value R1 'of the gas sensor 9a1, and this is displayed on the display unit 20.
However, the resistance value R1 ′ may be directly input to the display unit 20 as the gas concentration and displayed. The CPU 10 further includes a setting unit that sets a value R1′1 of the resistance value R1 ′ for starting the operation of the blower 7 and a value R1′2 of the resistance value R1 ′ for starting the operation of the air purifying unit 6. When the resistance value R1 ′ exceeds R1′1, the operation of the blower 7 may be started, and when the resistance value exceeds R1′2, the operation of the air cleaning unit 6 may be started.

[0015]

As described above, according to the gas detection device of the present invention, the ambient temperature is output by calculating the resistance value of the gas sensor and the resistance value of the thermistor from two detection signals from the gas sensor unit. At the same time, it is possible to calculate and output a highly accurate resistance value of the gas sensor in consideration of the temperature dependency, and simultaneously display a highly accurate gas concentration. In addition, if the gas detection device of the present invention is used in an air conditioner or the like, the blower fan and the air cleaning unit of the air conditioner are controlled based on the highly accurate gas concentration detected by the gas detection device. Thereby, a comfortable indoor environment can be provided.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a main part of an embodiment of an air conditioner using a gas detection device.

FIG. 2 is a circuit diagram showing one embodiment of a gas detection device according to the present invention.

FIG. 3 is a table showing one embodiment of a temperature table of the gas detector according to the present invention.

FIG. 4 is a table showing one embodiment of a correction value table of the gas detection device according to the present invention.

FIG. 5 is a chart showing one embodiment of a gas concentration table of the gas detection device according to the present invention.

FIG. 6 is a circuit diagram showing a conventional gas detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 1a Base 1b Front panel 2 Suction port 2a Air filter 3 Air outlet 4 Air passage 5 Heat exchanger 6 Air purification unit 7 Blower 8 Room temperature sensor 9 Gas detector 9a Gas sensor part 9a1 Gas sensor 9a2 Load resistance 9a3 Thermistor 9a4 Fixed resistance Series circuit 9b Correction means 9b1, 9b2 A / D conversion section 9b2 Load resistance 9b3 Calculation section 9b4 Output section 9b5 Control section 9b6 Blower drive section 9b7 Air purifier drive section 10 CPU 10a Storage section 10b Gas concentration setting section 20 Display section

Claims (5)

[Claims] 1. A gas sensor for outputting a gas detection signal corresponding to a gas concentration, a temperature sensor for outputting a temperature detection signal corresponding to an ambient temperature, and a gas detection signal outputted from the gas sensor from the temperature sensor. A gas detection device comprising correction means for correcting the temperature with a temperature detection signal, wherein the temperature sensor is provided integrally with the gas sensor unit. 2. The gas sensor section comprises: a gas sensor having a resistance value that varies according to a gas concentration; and a series circuit of a thermistor serving as a load resistance of the gas sensor and a fixed resistor. 2. The gas detection device according to claim 1, wherein a connection point and a connection point between the thermistor and the fixed resistor serve as an output terminal. 3. The resistance value of the gas sensor and the resistance value of the load resistance are made substantially the same value, and the temperature characteristic of the resistance value of the thermistor and the temperature characteristic of the resistance value of the gas sensor are made substantially the same. The gas detection device according to claim 2, wherein the detection accuracy is improved. 4. The correction means is connected to the two output terminals, and calculates the resistance values of the gas sensor and the thermistor by measuring respective terminal voltages of the load resistance and the fixed resistance. The gas detection device according to claim 2 or 3, wherein the resistance value is converted into a temperature and output, and the resistance value of the gas sensor is corrected and output based on the ambient temperature. 5. A conversion table for converting the corrected resistance value of the gas sensor into a gas concentration in the correction means,
The gas detection device according to claim 4, wherein the gas concentration converted by the conversion table is output.