JP2000329736A - Circuit for controlling carbon monoxide sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect carbon monoxide even if the zero point of sensor output fluctuates with the time elapsed in the control circuit of the carbon monoxide sensor of voltage output. SOLUTION: The control circuit successively compares an output voltage after the voltage between electrodes 2 and 3 being installed on a solid electrolyte plate 1 is amplified by an amplifier 8 with the output of a storage voltage- outputting means 12 by a voltage comparator 9 according to the instruction of a storage instruction switch 11, stores the matched voltage by a storage means 10, and outputs a voltage value corresponding to a value being stored by the storage means 10 using the storage voltage-outputting means 12. The output of the storage voltage-outputting means 12 cannot be updated until the storage instruction switch 11 is pressed and continues to be retained as a voltage that becomes a zero-point voltage when the concentration of carbon monoxide is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon monoxide sensor used for air-fuel ratio control of a combustion device, an incomplete combustion warning of a combustion device, and the like, and in particular, control for setting a zero point of the carbon monoxide sensor. It is related to the circuit.

[0002]

2. Description of the Related Art In the conventional carbon monoxide detection control of a carbon monoxide detector, a reference value (hereinafter referred to as a zero point) corresponding to the origin of an alarm output as shown in FIG. 10 (Japanese Utility Model Laid-Open No. 5-90148). It is stored in a storage means, compared with the output of the carbon monoxide sensor, and issues an alarm when it is detected that a difference between the sensor output and the zero point exceeds a predetermined value.

[0003]

However, in the conventional carbon monoxide detection control shown in FIG. 10, the control device for controlling the combustor main body constantly monitors the combustion state of the burner of the combustion equipment main body, and performs the combustion. The sensor output is measured when the device itself is not burning, the sensor output is stored in the storage means (zero point update), and the difference between the sensor output and the zero point is constantly monitored to determine whether the combustion state is normal. It was necessary to make a judgment. Therefore, there is a problem that control of the main body of the combustion equipment becomes complicated. Further, the zero point of the sensor fluctuates due to the change with time of the sensor, but since the zero point of the sensor is the origin of carbon monoxide detection, it is always necessary to know the zero point.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a carbon monoxide sensor element in which a voltage is output between electrodes, and an amplifying voltage between electrodes of the carbon monoxide sensor element. Storage means for holding the output voltage value of the amplification means, storage instruction means for instructing the storage means to hold the voltage value, storage voltage output means for outputting the voltage stored by the storage means, and storage voltage by the storage instruction means When the hold is commanded, the storage voltage output means sequentially increases the output voltage of the amplifier while increasing the output voltage at regular intervals when the output voltage of the storage voltage output means is smaller than the output voltage of the amplification means. When the output voltage exceeds the amplified voltage, the storage voltage output means stops changing the output.On the other hand, when the output voltage of the storage voltage output means is higher than the output voltage of the amplification means, , The output voltage of the amplifier is successively compared with the output voltage of the amplifier while decreasing the voltage at regular intervals. When the output voltage falls below the amplified voltage, the storage voltage output means stops changing the output, and the storage means Is to store the voltage at the time when the storage voltage output means stops changing the output.

According to this method, the control device does not need to store or calculate the value to be output, and has the advantage that the zero point can be set only by giving an instruction. Even so, you can always set the latest zero point.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a carbon monoxide sensor element for outputting a voltage between electrodes, an amplifying means for amplifying a voltage between the electrodes of the carbon monoxide sensor element, and an output voltage value of the amplifying means. Storage means for holding, storage instruction means for instructing the storage means to hold a voltage value, storage voltage output means for outputting the voltage value stored by the storage means, and storage voltage output when the storage voltage instruction is given by the storage instruction means When the output voltage of the storage voltage output means is smaller than the output voltage of the amplification means, the means sequentially compares the output voltage with the amplified voltage while increasing the output voltage at regular intervals, so that the output voltage is equal to the amplified voltage. At this point, the storage voltage output means stops changing the output.On the other hand, when the output voltage of the storage voltage output means is larger than the output voltage of the amplification means, the output voltage is decreased at regular intervals. While The output voltage of the amplifier is sequentially compared with the output voltage of the amplifier, and when the output voltage falls below the output voltage of the amplifier, the storage voltage output means stops changing the output, and the storage means stops changing the output. This is to store the voltage at the point of time. The current zero point output is compared with the magnitude of the output voltage of the storage voltage output means, and depending on the magnitude, the voltage is increased or decreased in one direction and successively compared, so that a new zero point voltage is quickly obtained. The zero point voltage can be output while being stored in the storage means.

Further, a carbon monoxide sensor element section in which a voltage is output between the electrodes, amplification means for amplifying a voltage between the electrodes of the carbon monoxide sensor element section, and storage means for holding the output voltage value of the amplification means, and storage. The storage instruction means for instructing the means to hold the voltage value, the storage voltage output means for outputting the voltage stored by the storage means, and the change of the output voltage at regular intervals when the storage voltage instruction is issued by the storage instruction means While letting
Successively, the comparison with the amplified voltage is performed, and when the output voltage reaches the output voltage of the amplifier, the storage voltage output unit stops changing the output, and the storage unit stops changing the output. The voltage at the time is stored, and the storage means and the storage voltage output means shift to a constant power operation. After setting a new zero point, the storage unit and the storage voltage output unit can reduce noise and prevent malfunction by reducing power.

In addition, a carbon monoxide sensor element for outputting a voltage between the electrodes, amplifying means for amplifying a voltage between the electrodes of the carbon monoxide sensor element, storage means for holding the output voltage of the amplifying means, and storage means And a storage voltage range setting unit for specifying a voltage range held by the storage unit. By setting the storage voltage range, the reliability of the sensor can be improved.

Further, a carbon monoxide sensor element portion for outputting a voltage between the electrodes, amplifying means for amplifying a voltage between the electrodes of the carbon monoxide sensor element portion, a storage means for holding an output voltage of the amplification means, and a storage means Storage instruction means for instructing the holding of the voltage value to the storage voltage range setting means for instructing the range of the voltage held in the storage means, and a warning means for warning that the storage voltage range setting means deviated from, It is possible to warn of a sensor failure.

[0010] A carbon monoxide sensor element for outputting a voltage between the electrodes, amplifying means for amplifying a voltage between the electrodes of the carbon monoxide sensor element, storage means for holding the output voltage of the amplifying means, and storage means Storing a plurality of voltage values in the storage instruction means and the storage means for instructing the holding of the voltage value to the
By comparing the history of the zero point voltage, it is possible to quickly detect a sensor failure.

[0011] Further, a carbon monoxide sensor element portion in which a voltage is output between the electrodes, amplifying means for amplifying a voltage between the electrodes of the carbon monoxide sensor element portion, a storage means for holding an output voltage of the amplifying means, and a storage means Storage instruction means for instructing the holding of the voltage value to the storage means and a change warning means for holding a plurality of voltage values in the storage means, calculating the magnitude of the voltage and issuing a warning, and promptly detecting and warning a sensor failure. Can be emitted.

An embodiment of the present invention will be described below with reference to FIGS.

[0013]

(Embodiment 1) FIG. 1 is a configuration diagram of a control circuit of a carbon monoxide sensor according to Embodiment 1 of the present invention. 2 and 3 are diagrams showing output voltages of the amplifier 8 and the storage voltage output means 12. In the figure, (a) shows the output voltage of the amplifier 8, and (b) shows the output voltage of the storage voltage output means 12.

In FIG. 1, reference numeral 1 denotes a solid electrolyte plate having oxygen ion conductivity at a high temperature of 400 ° C. to 500 ° C. A pair of electrodes 2 and 3 are provided on the surface thereof. Formed by electron beam evaporation, sputtering, or thick film printing. A platinum electrode is usually used as the electrode.

Reference numeral 4 denotes a ceramic paper impregnated and held with an oxidation catalyst for carbon monoxide (the drawing is partially cut away), and has air permeability and covers the electrode 2. Reference numeral 5 denotes a heater formed on the surface of the ceramic plate 6 by vapor deposition or printing, and heats the solid electrolyte plate 1 and the ceramic paper 4 to operate as a carbon monoxide sensor. The solid electrolyte plate 1, the ceramic plate 6, and the ceramic paper 4 constitute a carbon monoxide sensor element section 7. The outputs of the electrodes 2 and 3 are input to the amplifier 8, the output of the amplifier 8 is connected to one of the input terminals of the voltage comparator 9, the output of the voltage comparator 9 is connected to the storage means 10, and the storage instruction switch 11 is also stored. It is connected to the means 10. The output from the storage means 10 is the storage voltage output means 1
2, the output of the storage voltage output means 12 is connected to another input terminal of the voltage comparator 9 and compared with the output of the amplifier 8.

First, the operation of the carbon monoxide sensor having the above configuration will be described. The carbon monoxide gas that has passed through the ceramic paper 4 is oxidized when passing through the ceramic paper 4 and does not reach the electrode 2. Therefore, in the vicinity of the electrode 2 in the solid electrolyte plate 1, the oxygen atom adsorbed on the electrode 2 is ionized by the reaction represented by the formula (1).

O + 2e ⁻ → O ^2- (1) On the other hand, in addition to the reaction represented by the equation (1) near the electrode 3, the reaction represented by the equation (2) is also performed because carbon monoxide gas arrives. stay up.

CO + O ^2- → CO ₂ + 2e ⁻ (2) Then, a potential difference is generated between the electrodes 2 and 3 due to a difference in the reaction in the vicinity of the electrodes 2 and 3 of the solid electrolyte plate 1. That is, the potential difference changes according to the concentration of carbon monoxide, and the device operates as a carbon monoxide sensor.

The heater 5 is a heat source for heating the solid electrolyte plate 1 and the ceramic paper 4 to a constant temperature so that the reactions of the formulas (1) and (2) occur stably.

The output of the voltage comparator 9 is input to the storage means 10 according to the instruction of the storage instruction switch 11. In FIG. 2, an instruction is issued from the storage instruction switch 11 at a time point t1. While the input to the storage means 10 is at the LOW level, the output voltage of the storage voltage output means 12 is increased by one level, and the voltage comparator 9 repeats successive comparisons until the input to the storage means 10 becomes the HIGH level. The comparison is stopped at the time of the high level, the voltage value at that time is stored in the storage means 10, and the voltage is output from the storage voltage output means 12.
On the other hand, as shown in FIG.
While the input to the storage means 10 is at the HIGH level from the point in time of the instruction, the output voltage of the storage voltage output means 12 is reduced by one level, and the voltage comparator 9 successively compares the output voltage until the input to the storage means 10 becomes the LOW level. repeat. The comparison is stopped when the signal goes to the LOW level, and the voltage value at that point is stored in the storage unit 1.
0 and the voltage is output from the storage voltage output means 12. The output voltage is stored in the storage instruction switch 1
It is not changed until the instruction of 1. With such a configuration, it is possible to store and output the voltage at the zero point which is the origin for detecting the voltage change of the carbon monoxide sensor. If an electrically rewritable EEPROM (electrically erasable programmable read-only memory) is used as the storage means, the previous value will be stored the next time the power is turned on even if the circuit power is turned off. , It is possible to output the previous value.

The carbon paper oxide catalyst may be held in place of the ceramic paper 4 and may be made of a gas permeable material. For example, even if a fibrous metal is used, the effect is not changed. The same applies to the following embodiments.

(Embodiment 2) FIG. 4 is a configuration diagram of a carbon monoxide sensor control circuit according to Embodiment 2 of the present invention. 5A and 5B are characteristic diagrams showing the output voltage of the amplifier, FIG. 5B is a characteristic diagram showing the output voltage of the storage voltage output unit, and FIG. 5C is a characteristic diagram showing the power consumption of the storage unit. .

When the storage instruction switch 11 is pressed at time t1, it is input to the interrupt terminal (INT) of the EEPROM, and
As shown in FIG. 7, the output of the storage voltage output means 12 is reset once, and the voltage of the amplifier 8 is increased while increasing the voltage at a constant voltage level.
And successive approximation. When the output of the amplifier 8 is reached, the successive approximation is stopped and the power consumption is returned to the low power state. In the constant power state, the magnitude of noise generated from the electronic circuit is reduced, and the reliability of the sensor circuit that controls the carbon monoxide sensor is improved.

(Embodiment 3) FIG. 6 is a configuration diagram of a control circuit of a carbon monoxide sensor according to Embodiment 3 of the present invention.

The output voltage of the amplifier 8 is equal to the upper limit voltage comparator 13
Is connected also to the plus input terminal of the lower limit voltage comparator 14 and the minus input terminal of the upper limit voltage comparator 13 to the upper limit voltage generator 15.
The lower limit voltage generator 16 is connected to the plus input terminal of the third, and the output terminals of the upper limit voltage comparator 13 and the lower limit voltage generator 15 are connected to the input of the OR 17. With this configuration, when the output voltage of the amplifier 8 is in the range between the upper limit and the lower limit voltage, LOW is output to the output of the logical sum 17, and when the output voltage of the other amplifier 8 is out of the storage voltage range, the logic is low. HIGH is output as the output of the sum 17. Logical sum of 17
By confirming the LOW output and successively comparing the output voltage of the amplifier 8 and the storage voltage output means 12, the zero point can be rewritten only when the zero point is not largely shifted, thereby improving the reliability of the sensor circuit. Can be improved.

(Embodiment 4) FIG. 7 is a configuration diagram of a control circuit of a carbon monoxide sensor according to Embodiment 4 of the present invention.

An alarm 18 is connected to the output of the logical sum 17. By issuing an alarm in this way, it is possible to reliably issue an alarm.

(Embodiment 5) FIG. 8 is a configuration diagram of a control circuit of a carbon monoxide sensor according to Embodiment 5 of the present invention. The first voltage storage unit 19 and the second voltage storage unit 20 installed inside the storage unit 10 record past voltages when the storage instruction unit 11 is pressed. By recording a plurality of voltage values in this manner, it is possible to know a past history.

(Embodiment 6) FIG. 9 is a configuration diagram of a control circuit of a carbon monoxide sensor according to Embodiment 6 of the present invention. By comparing the voltage values recorded in the first voltage storage unit 19 and the second voltage storage unit 20 installed inside the storage means 10,
If the difference is equal to or less than the set value, the output of the storage voltage output means 12 is updated. If the difference is equal to or more than the set value, an alarm is issued from the fluctuation alarm 21. Having a history of a plurality of voltage values in this way makes it possible to further enhance the reliability of the sensor circuit.

[0030]

The present invention is embodied in the form described above and has the following effects.

The current zero-point output is compared with the magnitude of the storage voltage output means, and the magnitude of the magnitude is increased or decreased in one direction and successively compared, so that a new zero-point voltage is quickly obtained. The zero point voltage can be output while being stored in the storage means.

When the zero point voltage is output, low power operation is performed to reduce noise and increase the reliability of the circuit.

The reliability of the circuit can be improved by setting the upper and lower limits of the fluctuation range of the zero point and confirming that the range is within the range.

By alarming that the sensor is out of the range of the zero point, a defect of the sensor can be notified.

The change history of the zero point of the sensor can be known.

The warning of the zero point change history of the sensor can improve the reliability of the circuit.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control circuit of a carbon monoxide sensor according to a first embodiment of the present invention.

FIG. 2 is an output voltage characteristic diagram of the amplifier and the storage voltage output unit according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating output voltages of an amplifier and a storage voltage output unit according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of a control circuit of a carbon monoxide sensor according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating output voltages of an amplifier and a storage voltage output unit according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of a control circuit of a carbon monoxide sensor according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of a control circuit of a carbon monoxide sensor according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram of a control circuit of a carbon monoxide sensor according to a fifth embodiment of the present invention.

FIG. 9 is a configuration diagram of a control circuit of a carbon monoxide sensor according to a sixth embodiment of the present invention.

FIG. 10 is a configuration diagram of a control circuit of a carbon monoxide sensor in a conventional combustion device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solid electrolyte board 2, 3 electrode 4 Ceramic paper (carbon monoxide oxidation catalyst layer) 5 Heater 6 Ceramic board 7 Carbon monoxide sensor element part 8 Amplifier 9 Voltage comparator storage means 10 Storage means 11 Storage instruction switch 12 Storage voltage output Means 13 Upper limit voltage comparator 14 Lower limit voltage comparator 15 Upper limit voltage generator 16 Lower limit voltage generator 17 Logical sum 18 Alarm device 19 First voltage storage unit 20 Second voltage storage unit 21 Fluctuation alarm

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kunihiro Tsuruta 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. Terms (reference) 2G004 BB04 BJ03 BL19 BL20 BM01 BM04

Claims (6)

[Claims] A carbon monoxide sensor element having a pair of electrodes; amplifying means for amplifying a voltage between the electrodes of the carbon monoxide sensor element; storage means for holding an output voltage value of the amplifying means; Storage instruction means for instructing the storage means to hold the voltage value, storage voltage output means for outputting the voltage stored in the storage means, and when the storage voltage instruction is issued by the storage instruction means, the storage voltage output means stores the storage voltage. When the output voltage of the voltage output means is smaller than the output voltage of the amplifying means, the output voltage is increased at regular intervals, and sequentially compared with the output voltage of the amplifier. When the output voltage exceeds the output voltage of the storage voltage output means, the storage voltage output means stops changing the output, while when the output voltage of the storage voltage output means is higher than the output voltage of the amplification means, While decreasing the voltage at regular intervals, the voltage is successively compared with the amplified voltage, and when the output voltage falls below the output voltage of the amplifier, the storage voltage output means stops changing the output. A control circuit for the carbon monoxide sensor, wherein the storage means stores a voltage value at the time when the storage voltage output means stops changing the output. 2. A carbon monoxide sensor element having a pair of electrodes, amplifying means for amplifying a voltage between the electrodes of the carbon monoxide sensor element, storage means for holding an output voltage value of the amplifying means, and the storage. Storage instruction means for instructing the voltage value to be stored in the storage means, storage voltage output means for outputting the voltage stored in the storage means, and when the storage voltage instruction is issued by the storage instruction means, the output voltage is changed at regular intervals. Are sequentially compared with the amplified voltage, and when the output voltage reaches the output voltage of the amplifier, the storage voltage output means stops changing the output, and the storage means changes the storage voltage. A control circuit for a carbon monoxide sensor which stores a voltage value at a time when an output means stops changing output, and wherein the storage means and the stored voltage output means shift to a constant power operation. 3. A carbon monoxide sensor element having a pair of electrodes, amplifying means for amplifying a voltage between the electrodes of the carbon monoxide sensor element, storage means for holding an output voltage value of the amplifying means, and the storage. A control circuit for a carbon monoxide sensor, comprising: storage instructing means for instructing the means to hold a voltage value; and storage voltage range setting means for setting a voltage range held in the storage means. 4. A carbon monoxide sensor element having a pair of electrodes, amplifying means for amplifying a voltage between the electrodes of the carbon monoxide sensor element, storage means for holding an output voltage value of the amplifying means, and the storage. Storage means for instructing the means to hold the voltage value, storage voltage range setting means for setting the range of the voltage held in the storage means, and warning means for warning that the voltage is out of the storage voltage range setting means. Control circuit for carbon oxide sensor. 5. A carbon monoxide sensor element having a pair of electrodes, amplifying means for amplifying a voltage between electrodes of said carbon monoxide sensor element, storage means for holding an output voltage value of said amplifying means, and said storage. And a control circuit for a carbon monoxide sensor in which a plurality of voltage values are stored in the storage unit. 6. A carbon monoxide sensor element having a pair of electrodes, amplifying means for amplifying a voltage between electrodes of said carbon monoxide sensor element, storage means for holding an output voltage value of said amplifying means, and said storage. A control circuit for a carbon monoxide sensor, comprising: storage instructing means for instructing the means to hold a voltage value; and a fluctuation warning means for holding a plurality of voltage values in the storage means, calculating the magnitude of the voltage, and issuing a warning.