JPS62106361A - Apparatus for detecting concentration of oxygen - Google Patents

Abstract

PURPOSE:To obtain oxygen concn. detection output characteristic having good linearity in a wide range from a lean region to a rich region, by calculating an oxygen concn. detection value from the supply current value of the pump current supply means between a pair of electrodes. CONSTITUTION:When the air-fuel ratio of an engine supply gaseous mixture is resent in a lean region in a sensor selection state, the positive level voltage of a differential amplifying circuit 22 is supplied to a series circuit of a resistor 24 and an oxygen pump element 15 and a pump current flows between the electrodes 11a, 11b of the element 15. Oxygen in a gas stagnation chamber 2 is ionized at the electrode 11b by said pump current to move through the element and discharged from the electrode 11a as oxygen gas and oxygen in the chamber 2 is pumped out. By this pumping-out action, oxygen concn. difference is generated between the exhaust gas in the chamber 2 and the gas in a reference gas chamber to generate voltage Vs between electrodes 12a, 12b and said voltage Vs is supplied to the reversal input terminal of the differential amplifying circuit 22 and, because the output voltage of the circuit is proportional to the difference voltage of the voltage Vs and the output voltage of a reference voltage source 26, the pump current value is proportional to the concn. of oxygen in exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oxygen concentration detection device for detecting oxygen concentration in gas such as engine exhaust gas.

For the purpose of purifying the exhaust gas of an internal combustion engine and improving fuel efficiency, the oxygen concentration in the exhaust gas is detected, and the air-fuel ratio of the air-fuel mixture supplied to the engine is feedback-controlled to the target air-fuel ratio according to the detection results. There is an air-fuel ratio control device that does this.

As an oxygen concentration detection device used in such an air-fuel ratio control titl device, there is one that generates an output proportional to the oxygen concentration in the gas to be measured. For example, electrode pairs are provided on both main surfaces of a flat oxygen ion conductive solid electrolyte member, and one electrode surface of the solid electrolyte member forms part of a gas retention chamber, and the gas retention chamber is introduced with the gas to be measured. A limiting current type oxygen concentration detection device that communicates through a hole was published in Japanese Patent Application Laid-Open No. 1983-
It is disclosed in Japanese Patent No. 72286. In this oxygen concentration detection device, when the oxygen ion conductive solid electrolyte member and the electrode pair act as an oxygen pump element and a current is supplied between the electrodes so that the electrode on the gap chamber side becomes the negative electrode, the electrode on the negative electrode side Oxygen gas in the gas in the gas i-retention chamber is ionized, moves within the solid electrolyte member toward the positive electrode surface, and is released as oxygen gas from the positive electrode surface.

The limiting current value that can flow between the electrodes at this time is almost constant regardless of the applied voltage and is proportional to the oxygen concentration in the gas being measured, so if the limiting current value is detected, the oxygen concentration in the gas being measured can be measured. be able to. However, when controlling the air-fuel ratio using such an oxygen concentration detection device, an output proportional to the oxygen concentration can only be obtained from the oxygen concentration in the exhaust gas when the air-fuel ratio of the mixture is leaner than the stoichiometric air-fuel ratio. Therefore, it was impossible to control the air-fuel ratio by setting the target air-fuel ratio in the rich range. In addition, as an oxygen concentration detection device that can obtain an output proportional to the oxygen concentration in exhaust gas when the air-fuel ratio is in the lean and rich regions, two electrode pairs are provided on each of two flat oxygen ion conductive solid electrolyte members. One electrode surface of the solid electrolyte member forms a part of a gas retention chamber, and the gas retention chamber communicates with the gas to be measured through an introduction hole, and the other electrode surface of one solid electrolyte member is exposed to atmospheric air. A device designed to face each other is disclosed in Japanese Patent Laid-Open No. 59-192955. In this oxygen concentration detection device, one oxygen ion conductive solid electrolyte member and electrode pair act as an M element concentration ratio detection battery element, and the other oxygen ion conductive solid electrolyte material and electrode pair act as an oxygen pump element. It is supposed to be done.

When the voltage generated between the electrodes of the oxygen concentration ratio detection battery element is equal to or higher than the reference voltage, a current is supplied so that oxygen ions move within the oxygen pump element toward the electrode on the gas retention chamber side, and the oxygen concentration ratio detection battery element By supplying current so that when the voltage generated between the electrodes is below the reference voltage, the oxygen ions move within the oxygen pump element toward the electrode on the opposite side from the side where gas is retained, the air-fuel ratio in the lean and rich regions can be controlled. The current value is proportional to the oxygen concentration. However, in such an oxygen concentration detection device, the oxygen concentration detection characteristics are different between the rich side and the lean side, and oxygen concentration detection output with good linearity cannot be obtained in a wide area. There was a problem in that the detected output had to be corrected, making air-fuel ratio control complicated.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an oxygen my1 detection device that can obtain an oxygen concentration detection output with good linearity over the lean and rich air-fuel ratio regions.

The oxygen concentration detection device of the present invention includes a base body forming first and second gas retention chambers and a gas introduction chamber, each having an oxygen ion conductive solid electrolyte wall, and inner and outer wall surfaces of the electrolyte wall of the first gas retention chamber. Two first electrode pairs are provided on the top so as to be sandwiched therebetween, and two electrode pairs are provided on the inner and outer wall surfaces of the electrolyte wall portion of the second gas retention chamber so as to be sandwiched therebetween.
according to the voltage difference between the first reference voltage and the voltage generated between the two second electrode pairs, the pair of heater elements provided on the outer wall surface of the base, and one of the two first electrode pairs. A value corresponding to the voltage difference between the voltage generated between one electrode pair of the two second electrode pairs and the second reference voltage. pump current supply means for supplying a current between the other of the two second electrode pairs;
heater current supply means for supplying current to the pair of heater elements, the gas introduction chamber communicates with the outside via the introduction hole, and the first
It is characterized by communicating with the gas retention chamber through the first communication hole and communicating with the second gas retention chamber through the second communication hole, and obtaining an oxygen concentration detection value according to the current value supplied by the pump current supply means. It is said that

Friend-lid-1 Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an air-fuel ratio control device using an oxygen concentration detection device according to the present invention. In this device,
An oxygen ion conductive solid electrolyte member 1 having a substantially cubic shape is provided. In the oxygen ion conductive solid electrolyte member 1, first and second gas retention spaces 2, 3 and a gas introduction chamber 4 are formed. The gas introduction chamber 4 communicates with an introduction hole 5 through which the exhaust gas of the gas to be measured is introduced from outside the solid electrolyte member 1. It is located so that it can easily flow into the area. Gas introduction chamber 4 and first and second gas retention chambers 2, 3
A communication hole 6°7 is formed in each wall between the two. The diameter of the communication hole 6 is made larger than the diameter of the communication hole 7. The exhaust gas enters the first gas retention chamber 2 through the introduction hole 5 and the gas introduction chamber 4.
, and is introduced through the communication hole 6, and exhaust gas is introduced into the second gas retention chamber 3 through the introduction hole 5, the gas introduction v4, and the communication hole 7. ing. The oxygen ion conductive solid electrolyte member 1 includes a reference gas chamber 8 into which outside air, etc. is introduced, and a first and second gas retention chamber 2.
．． It is formed to separate 3 and a wall. The wall between the first gas retention chamber 2 and the gas introduction chamber 4 and the first gas retention chamber 2
On the wall between the reference gas chamber 8 and the reference gas chamber 8, there are electrode pairs 11a and llb.
, 12a, 12b are formed respectively, and an electrode pair 13a is formed on the wall between the second gas retention chamber 3 and the gas introduction chamber 4 and on the wall between the second gas retention chamber 3 and the reference gas chamber 8. , 13b,
14a and 14b are formed respectively. electrode pair 11a,
11b has a through hole communicating with the communication hole 6 in the center, and the electrode pair 13a, 13b also has a through hole communicating with the communication hole 7 in the center.

The solid electrolyte member 1 and the electrode pair 11a and 11b serve as the first oxygen pump element 15, and the solid electrolyte member 1 and the electrode pair 1
2a and 12b each act as a first battery element 16.

Further, the solid electrolyte member 1 and the electrode pair 13a, 13b are connected to the first
As the oxygen pump element 15, the solid electrolyte member 1 and the electrode pair 14a, 14b each act as the second battery element 18. Furthermore, heater elements 19 and 20 are provided on the outer wall surface of the gas introduction chamber 4 and the outer wall surface of the reference gas chamber 8 of the solid electrolyte member 1, respectively. The heater elements 19, 20 are electrically connected in parallel to each other and the first and second oxygen pump elements 1
5.17 and the first and second battery elements 16.18 are uniformly heated, and the heat retention within the solid electrolyte member 1 is improved. Note that the oxygen ion conductive solid electrolyte member 1
is integrally formed from multiple pieces. Also the first and second
It is not necessary that the entire wall of the gas retention chamber be made of the oxygen ion conductive solid electrolyte, and it is sufficient that at least only the portion where the electrode pair is provided is made of the solid electrolyte.

As the oxygen ion conductive solid electrolyte member 1, ZrO2
(zirconium dioxide) is used, and Pt (platinum) is used as the electrodes 11a to 14b.

A current supply circuit 21 is connected to the first and second oxygen pump elements 15.17 and the first and second battery elements 16.18. As shown in FIG. 2, the current supply circuit 21 includes differential amplifier circuits 22, 23 . Current detection resistor 24.25. It consists of a reference voltage source 26.27 and a switching circuit 28.29. 1st
The outer electrode 11a of the oxygen pump element 15 is connected to the output terminal of the differential amplifier circuit 22 via the switch 28a of the switching circuit 28 and the current detection resistor 24, and the inner electrode 11b is grounded via the two switches 29a of the switching circuit 28. It has become so. The outer electrode 12a of the first battery element 16 is connected to the inverting input terminal of the differential amplifier circuit 22, and the inner electrode 12b is grounded via two switches 29b of the switching circuit.

Similarly, the outer electrode 13a of the second oxygen pump element 17 is connected to the output terminal of the differential amplifier circuit 23 via the switch 28b of the switching circuit 28 and the current detection resistor 25, and the inner electrode 13b
is grounded via a switch 29a of the switching circuit 29. Outer electrode 14a of second battery element 18
is connected to the inverting input terminal of the differential amplifier circuit 23, and the inner electrode 14b is grounded via two switches 29b of the switching circuit. A reference voltage source 26 is connected to the non-inverting input terminal of the differential amplifier circuit 22.
A reference voltage source 27 is connected to the non-inverting input terminal of 3. Basic +1! The output voltage of the voltage sources 26 and 27 is a voltage corresponding to the stoichiometric air-fuel ratio (for example, 0.4V). A portion between both ends of the current detection resistor 24 serves as the output of the first sensor, and a portion between both ends of the current detection resistor 25 serves as the output of the second sensor. The voltage across the current detection resistor 24.25 is supplied to the air-fuel ratio control circuit 32 via the differential input A/D converter 31, and the pump current value 1p(1), I flowing through the current detection resistor 24.25 is
p(2) is read into the air-fuel ratio control circuit 32. The air-fuel ratio control circuit 32 consists of a microcomputer. The air-fuel ratio control circuit 32 includes a plurality of operating parameter detection sensors (
A solenoid valve (not shown) is connected thereto, and a solenoid valve 34 is also connected via a drive circuit 33. The solenoid valve 34 is provided in a secondary intake air supply passage (not shown) that communicates with the intake manifold downstream of the engine carburetor throttle valve. Further, the air-fuel ratio control circuit 32 controls the switching operation of the switching circuits 28 and 29, and the drive circuit 30 drives the switching circuits 28 and 29 in response to commands from the air-fuel ratio control circuit 32. Note that positive and negative power supply voltages are supplied to the differential amplifier circuits 22 and 23.

On the other hand, current is supplied to the heater cords 19, 20 from the heater current supply circuit 35, and the heater elements 19, 20 generate heat, heating the oxygen pump elements 15, 17 and the battery elements 16, 18 to an appropriate temperature higher than the exhaust gas. do.

In such a configuration, exhaust gas in the exhaust pipe passes through the introduction hole 5.
The gas flows into the gas introduction chamber 4 and diffuses therein, further flows into the first gas retention chamber 2 through the communication hole 6 and diffuses, and flows into the second gas retention chamber 3 through the communication hole 7. and spread.

In the switching circuits 28 and 29, switch 2 is connected as shown in FIG.
8a connects electrode 11a to current detection resistor 24, switch 28b opens the connection line of electrode 13a, switch 29a grounds electrode 11b and opens the connection line of electrode 13b, and switch 29b connects electrode 12b to When set to the selected position where the electrode 14b is grounded and the connection line of the electrode 14b is opened, the first sensor is in the selected state.

In the selection state of the first sensor, first, when the air-fuel ratio of the air-fuel mixture supplied to the engine is in the lean region, the differential amplifier circuit 22
The output level becomes a positive level, and this positive level voltage is supplied to the series circuit of the resistor 24 and the first oxygen pump element 15. Therefore, the electrode 11a of the first oxygen pump element 15,
A pump current flows between 11b and 11b. Since this pump current flows from the electrode 11a to the electrode 11b, oxygen in the first gas reservoir 2 is ionized at the electrode 11b, moves within the first oxygen pump element 15, and is released from the electrode 11a as oxygen gas. , the oxygen in the first gas retention chamber 2 is pumped out.

By pumping out the oxygen in the first gas retention chamber 2, a difference in oxygen concentration occurs between the exhaust gas in the first gas retention space 2 and the gas in the reference gas chamber 8. Due to this oxygen concentration difference, the battery element 16
A voltage Vs is generated between the electrodes 12a and 12b. This voltage Vs is supplied to the inverting input terminal of the differential amplifier circuit 22.

The output voltage of the differential amplifier circuit 22 is the voltage Vs and the reference voltage source 2.
Since the voltage is proportional to the difference voltage from the output voltage Vl'+ of No. 6, the pump current value is proportional to the oxygen concentration in the exhaust gas.

When the air-fuel ratio is in the rich region, the voltage Vs is the reference voltage source 2.
6 output voltage Vr+. Therefore, differential amplifier circuit 2
The output level of No. 2 is inverted from a positive level to a negative level. Due to this low level, the electrode 11a of the first oxygen pump element 15
, 11b decreases, and the current direction is reversed. That is, the pump current flows from electrode 11b to electrode 1.
Since it flows in the direction 1a, external oxygen is ionized at the electrode 11a and moves within the first oxygen pump element 15 to the electrode 11.
b is released into the first gas retention chamber 2 as oxygen gas,
Oxygen is pumped into the first gas retention chamber 2. Therefore, oxygen is pumped in and out by supplying the pump current so that the M element concentration in the first gas retention chamber 2 is always constant, so that the pump current value Ip and the output voltage of the differential amplifier circuit 22 are are proportional to the oxygen concentration in the exhaust gas in the lean and rich regions, respectively. A solid line a in FIG. 3 indicates the pump current value IP.

The pump current value Ip is determined by the following formula, where the charge is eX, the diffusion coefficient for the exhaust gas through the introduction hole 5 and the communication hole 6 is σ0, the oxygen concentration in the exhaust gas is Poexh, and the oxygen concentration in the first gas retention chamber 2 is PoV. It can be expressed as follows.

Ip = 4ecro (Poexh -PoV)--
(1) Here, the diffusion coefficient σ0 is the area of the introduction hole 5, A1,
The area of the communicating hole 6 is A2, the Boltzmann's constant is k, the absolute temperature is O, the length of the introduction hole 5 is (i+, the length of the communicating hole 6 is 92
, where D is the diffusion constant, it can be expressed as in the following equation.

σo-(At/u+ +A2/Q2)D/kT...
(2) Next, the switch 28a opens the connection line of the electrode 11a, the switch 28b connects the electrode 13a to the current detection resistor 25, and the switch 29a grounds the electrode 13b and closes the connection line of the electrode 11b. When the switch 29b is set to the selection position where the electrode 14b is grounded and the connection line of the electrode 12b is opened, the second sensor becomes selected.

In the selected state of the second sensor, the pump current is applied to the electrodes of the second oxygen pump element 17 so that the oxygen concentration in the second gas retention chamber 3 is always constant by the same operation as in the selected state of the first sensor described above. Since oxygen is supplied between 13a and 13b and pumped out, the pump current value is 1.
P and the output voltage of the differential amplifier circuit 23 are proportional to the oxygen concentration in the exhaust gas in the lean and rich regions, respectively.

The pump current value 1p in the second sensor selection state is determined by using the diffusion coefficient σO in the above equation (1) for the introduction hole 5 and the communication hole 7.
It is expressed by assuming that PoV is 8 degrees of oxygen in the second gas retention chamber 3. Pump current value 1p
As shown in FIG. 4, it has become clear that the magnitude of σ becomes smaller as the diffusion resistance, which is inversely proportional to the difference in the diffusion coefficient σ0, increases in the lean and rich air-fuel ratio regions. Therefore, in the second sensor selection state, the diffusion resistance is greater than in the first sensor selection state, so the magnitude of the pump current value Ip becomes smaller in the lean and rich regions as shown by the broken line in FIG. As shown in FIG. 3, by adjusting the magnitude and length of Ip = Ip =
It continues linearly at O. Also, the differential amplifier circuit 2
The output voltage characteristic of 2.23 also becomes linearly continuous at O(V).

In order to obtain such a linearly continuous output characteristic, the air-fuel ratio control circuit 32 operates as follows. Air-fuel ratio control circuit 3
2, as shown in FIG. 5, it is first determined whether the flag Fs representing the selection state of the first and second sensors is 111 I+ (step 51). If Fs = O, the first
Since the sensor is in the sensor selection state, the pump current value IP(1) of the first sensor output from the A/D converter 31 is read and the oxygen concentration detection output value L02 corresponding to the pump current value 1p(1) is differentially output. O( of the output voltage Vs+ of the amplifier circuit 22
LO2≧1refo(Vs
+≧O), the first sensor selection state is continued because it is a lean region, and 102 <LrefO(Vs l <
If O), then the second sensor selection command is issued to the drive circuit 30 because it is in the rich region.
Set the flag Fs to 1 to indicate that the sensor has been selected.
” is set (step 54). Meanwhile, Fs = 1
In this case, the A/D converter 3 is in the second sensor selection state.
Pump current of the second sensor output from 1! elp(2
) and check whether the oxygen concentration detection output value LO2 corresponding to the pump current value 1p(2) is less than the reference value 1rero corresponding to 0 (V) of the output voltage VS2 of the differential amplifier circuit 23. It is determined (step 55). LO2≦f
, refo (Vs 2≦0), it is a rich region, so the second sensor selection state continues, and LO2>Lr
If erO (Vs 2 >O), it is in the lean region, so a first sensor selection command is issued to the drive circuit 30 (step 56), and the flag Fs is set to O to indicate that the first sensor has been selected. ” is set (step 57
). The drive circuit 30 operates the switches 28a and 28b in response to the first selection command.

29a and 29b are driven to the first sensor selection position described above, and the driving state is maintained until the second sensor +j selection command is supplied from the air-fuel ratio control circuit 32.

The switch 28a also responds to the second sensor selection command.

28b, 29a, and 29b are driven to the second sensor selection position described above, and the driving state is maintained until the first sensor selection command is supplied from the air-fuel ratio control circuit 32. When the first or second sensor is selected in this way, the air-fuel ratio control circuit 3
2, it is determined whether the oxygen concentration detection output value LO2 of the first or second sensor output from the A/D converter 31 is larger than the target value Lre4 corresponding to the target air-fuel ratio (step 58). If o2≦1ref, the air-fuel ratio of the supplied air-fuel mixture is rich, so the solenoid valve 34
Step 59), Lo2>L
If it is ref, the air-fuel ratio of the supplied air-fuel mixture is lean, so a command to stop the opening drive of the solenoid valve 34 is issued to the drive circuit 33 (step 60).

The drive circuit 33 opens the solenoid valve 34 in response to the valve opening drive command to supply secondary air into the engine intake manifold to make the air-fuel ratio leaner, and opens the solenoid valve 34 in response to the valve opening drive stop command. 34 is stopped to enrich the air-fuel ratio. By repeating this operation at predetermined intervals, the air-fuel ratio of the supplied air-fuel mixture is controlled to the target air-fuel ratio. Note that in steps 52 and 55, the reference value 1. refo, i.e. the voltage V s I N V
The discrimination reference voltages of S2 are both set to O(V), but in order to provide hysteresis, the discrimination reference voltage of voltage Vs+ is set slightly smaller than O(V), and the discrimination reference voltage of VS2 is set to 0( V) may be set slightly larger than V).

In the embodiment of the present invention described above, different diffusion resistances are obtained by the through holes 6 and 7, but in order to obtain different diffusion resistances, the diameters of the through holes 6 and 7 are made equal and the diameters of the through holes 6 and 7 are made equal.
Gaps may be formed between the two first electrode pairs in the gas retention chamber 2 and between the two second electrode pairs in the second gas retention chamber 3, and the gap widths may be different.

Furthermore, in the embodiment of the present invention described above, the air-fuel ratio of the supplied air-fuel mixture is controlled to the target air-fuel ratio by supplying secondary air according to the output of the first or second sensor. However, the air-fuel ratio may be controlled by adjusting the fuel supply amount according to the output of the first or second sensor.

As described above, the oxygen concentration detection device of the present invention includes a gas introduction chamber into which the gas to be measured such as exhaust gas flows through the introduction hole, and a gas introduction chamber into which the gas to be measured such as exhaust gas flows through the communication holes. First and second gas retention chambers are provided which communicate with each other and have different diffusion resistances to the inflowing gas, and the first gas retention chamber is disposed on the inner and outer wall surfaces of the electrolyte wall of each of the first and second gas retention chambers and is opposed to the inner and outer walls of the electrolyte wall of each of the first and second gas retention chambers. Since a second electrode pair is formed, by adjusting the diffusion resistance due to the introduction hole, communication hole, etc., it is possible to obtain oxygen concentration detection output characteristics with good linearity proportional to the oxygen concentration in the gas to be measured in a wide range of lean and ridge regions. Obtainable.

Therefore, there is no need to correct the oxygen concentration detection output, making air-fuel ratio control easier, and improving air-fuel ratio control accuracy.

Furthermore, in the oxygen concentration detection device of the present invention, by providing a pair of heater elements on the outer wall surface of the base, the first and second oxygen pump elements and the first and second battery elements are equally heated as described above. This allows for good heat retention within the base. Furthermore, by providing a pair of heater elements and doubling the heating area compared to a single heater element, the amount of heat generated per unit area can be reduced. The durability of the material can be improved.

[Brief explanation of drawings]

FIG. 1(a) is a plan view showing an embodiment of the oxygen concentration detection device according to the present invention, and FIG. 1(b) is a plan view showing an embodiment of the oxygen concentration detection device according to the present invention.
A cross-sectional view of part b, Figure 2 is a circuit diagram showing the current supply circuit including the air-fuel ratio control device, Figure 3 is a diagram showing the output characteristics of the device in Figure 1, and Figure 4 is the diffusion resistance and pump current value. FIG. 5 is a flowchart showing the operation of the air-fuel ratio control circuit. Explanation of symbols of main parts 1...Oxygen ion conductive solid electrolyte members 2, 3
... Gas retention chamber 4 ... Gas introduction chamber 5 ... Introduction hole 6.7 ... Communication hole 8 ... Gas reference chamber 15 .17...Oxygen pump element 16.18...
...Battery element 19.20...Heater element 21...Current supply circuit

Claims (2)

[Claims] (1) A base body forming first and second gas retention chambers and a gas introduction chamber each having an oxygen ion conductive solid electrolyte wall, and a base body forming the first and second gas retention chambers and the gas introduction chamber, each having an oxygen ion conductive solid electrolyte wall, and a base body forming the first and second gas retention chambers, each having an oxygen ion conductive solid electrolyte wall, and a base body forming the first and second gas retention chambers, each having an oxygen ion conductive solid electrolyte wall, and a base body forming the first gas retention chamber and the inner and outer wall surfaces of the electrolyte wall of the first gas retention chamber. two first electrode pairs disposed so as to be sandwiched and facing each other; and two second electrode pairs disposed so as to be sandwiched and opposed on the inner and outer wall surfaces of the electrolyte wall portion of the second gas retention chamber. , a current having a value corresponding to a voltage difference between a first reference voltage and a voltage generated between a pair of heater elements provided on the outer wall surface of the base and one of the two first electrode pairs; is supplied between the other of the two first electrode pairs, and the current has a value corresponding to the difference voltage between the voltage generated between one of the two second electrode pairs and a second reference voltage. pump current supply means for supplying current between the other of the two second electrode pairs, and heater current supply means for supplying current to the pair of heater elements, and the gas introduction chamber has an introduction hole. communicates with the outside through the pump, communicates with the first gas retention chamber through a first communication hole, and communicates with the second gas retention chamber through a second communication hole, and is connected to the current value supplied by the pump current supply means. An oxygen concentration detection device characterized by obtaining a detected oxygen concentration value according to the oxygen concentration. (2) The oxygen concentration detection device according to claim 1, wherein the pair of heater elements are provided so as to face each other with the base body in between.