JPS62197759A - Activation detector for air/fuel ratio detector - Google Patents

Abstract

PURPOSE:To enable highly accurate detection of activation of a sensor quickly and accurately, by directly measuring an internal resistance at a detection element section. CONSTITUTION:An activation detecting circuit 20 is equipped with a constant current circuit 21 for supplying a fixed current to an oxygen pump element 4 of a sensor S from a porous electrode 3 side and a voltage detecting circuit 22 for detecting voltages generated in porous electrodes 2 and 3 at both ends of the element 4. It is also provided with an activation discriminating circuit 23 or the like which detects the activation of the sensor S and outputs an activation detection signal. The circuit 20 supplies a fixed current from the electrode 2 side which is directly contacting an ambient measuring gas of the element 4 with the circuit 21 and detects voltages currently generated between the electrodes 2 and 3 of the element 4 to measure an internal resistance of the element 4. Then, the circuit 23 determines whether the resulting measured value, namely, the voltage between the electrodes 2 and 3 is below a set voltage E0 to find that the element is activating with the internal resistance of the element 4 below a specified value thereby enabling accurate detection.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is an air-fuel system that detects the air-fuel ratio of a fuel mixture supplied to various combustion equipment, such as an internal combustion engine, based on the oxygen concentration in the exhaust gas of the combustion equipment. This is related to a fuel ratio sensor activation detection device.

[Prior Art] Conventionally, air-fuel ratio sensors have been used to detect the air-fuel ratio of a fuel mixture supplied to an internal combustion engine, etc. from the degree of oxygen in exhaust gas.
There is an air-fuel ratio sensor that includes a detection element formed by laminating porous electrodes on both sides of an oxygen ion conductive solid electrolyte.

In other words, for example, the detection element parts formed as described above are arranged opposite to each other with a gap in the exhaust gas that is the measurement gas, and one detection element part is used as an oxygen concentration battery element, and the other detection element part is used as an oxygen pump element. Run it as l! An air-fuel ratio sensor configured to detect the oxygen concentration in the exhaust gas from the voltage generated between the two electrodes of the Sobuchi light battery element or the current flowing through the oxygen pump element (Japanese Patent Application Laid-Open No. 178354/1983), or as described above. When a gas diffusion restriction chamber in which the diffusion of exhaust gas is restricted is formed on one porous electrode side of the configured detection element section, an oxygen sensor made of a transition metal oxide such as titania is disposed within the gas diffusion restriction chamber. An example of this is an air-fuel ratio sensor, etc., which is configured to detect the M depth in the exhaust gas from the current value by controlling the current flowing through the oxygen detection element section according to the detection characteristics of the oxygen sensor. .

By the way, in this keyaki air-fuel ratio sensor, in order to detect the air-fuel ratio satisfactorily, each of the above-mentioned detection elements needs to be at a predetermined temperature or higher and activated. For this reason, conventionally, this type of air-fuel ratio sensor has been equipped with an activation detection device to detect activation, and after confirming activation of the sensor, the air-fuel ratio can be detected. It is considered.

[Problems to be Solved by the Invention] However, in the conventional activation detection device, it is not possible to check the heating state of the sensor by checking the energization time of the heater installed in the air-fuel ratio sensor, the heater electric pole, etc. Since the activation of the air-fuel ratio sensor is determined by the air-fuel ratio sensor, activation of the air-fuel ratio sensor cannot be directly detected, and if the air-fuel ratio cannot be detected even if the air-fuel ratio sensor is activated, .

There was a problem.

In other words, for example, if the air-fuel ratio sensor is restarted after it has stopped operating, the air-fuel ratio sensor is naturally activated, but in the past, the air-fuel ratio sensor was activated.
When the heater is energized and a predetermined period of time has elapsed, activation of the air-fuel ratio sensor is confirmed. Until then, the air-fuel ratio cannot be detected even though the air-fuel ratio sensor is activated. , air-fuel conversion of internal combustion engines, etc. 1i11! There was a problem that they could not conduct their battles well.

SUMMARY OF THE INVENTION Therefore, the present invention provides an activation detection device for an air-fuel ratio sensor that can quickly and accurately detect activation of the air-fuel ratio sensor by directly measuring the internal resistance of the detection element. It was created with the following purpose:

[Means for Solving the Problems] That is, the structure of the present invention as a means for solving the above problems is as follows: A pair of porous electrodes are laminated on both sides of an oxygen ion conductive solid electrolyte, and the first porous An air-fuel ratio sensor comprising: a detection element portion in which a porous electrode is placed in direct contact with a gas to be measured, and a second porous electrode is placed in contact with the gas to be measured in a gas diffusion restriction chamber in which diffusion of the gas to be measured is restricted. An activation detection device comprising: current supply means for supplying a predetermined current to the detection element section from the second porous electrode side; and current supply from the current supply means to the first and second porous holes. an internal resistance measuring means for measuring the internal resistance of the detecting element section from the voltage generated between the electrodes; The present invention provides an activation detection device for an air-fuel ratio sensor, comprising: activation determining means for detecting activation of the air-fuel ratio sensor when .

Typical examples of the W1 ion-conducting solid electrolyte used in the detection element are a solid solution of zirconia and yttria, or a solid solution of zirconia and calcia, as well as cerium dioxide, thorium dioxide, and hafnium dioxide. Various solid solutions, velorskite oxide solid solutions, trivalent metal oxide solid solutions, etc. can also be used.

In addition, first and second electrodes are provided on both sides of the solid electrolyte, respectively.
The porous "f! electrode" may be made of platinum, rhodium, etc., which have a catalytic effect on oxidation reactions, and the method for forming it is to use powders of these metals as the main component and powder of the same ceramic material as the solid electrolyte. Examples include a method of mixing and forming a paste and sintering it after marking using a thick film technique, or a method of forming using a thin film technique such as flame melting rF11 chemistry, vapor deposition, etc. Since the porous electrode is in direct contact with the gas to be measured, ie, the exhaust gas, it is preferable to further form a porous protective layer of alumina, spinel, zirconia, mullite, etc. on the two-part electrode layer using thick film technology.

In the detection element section formed in this way, the first porous electrode is in direct contact with the measurement gas (exhaust gas), and the second porous electrode is in direct contact with the measurement gas (exhaust gas), and the second porous electrode is in direct contact with the measurement gas in the gas diffusion restriction chamber where the diffusion of the measurement gas is restricted. As explained in the prior art section, an air-fuel ratio sensor having this type of detection element section is arranged so as to be in contact with the gas (exhaust air).
- and an air-fuel ratio sensor that combines a detection element portion and an input sensor made of ditania or the like.

In addition, in recent years, air-fuel ratio sensors equipped with two detection elements have been developed whose detection characteristics change continuously according to the oxygen concentration in the measurement gas, making it possible to accurately detect the air-fuel ratio in any range. , atmospheric air is introduced into the electrode on the opposite side of the gas diffusion restriction chamber of the detection element used as an oxygen concentration battery element, and the atmosphere is introduced into the detection element used as an oxygen pump element so that the voltage generated in the oxygen concentration battery element is constant. flows.

``■ An air-fuel ratio sensor configured to control the flow in both directions and detect the oxygen concentration in the measured gas, that is, the air-fuel ratio, from the current value, or a detection element section used as an oxygen concentration cell element. By passing a current, oxygen is generated in the gas diffusion restriction chamber (the side of the electrode that is not in contact with the other), and the generated oxygen leaks to the outside or to the gas diffusion restriction chamber through the leakage resistance part, and this electrode side An air-fuel ratio sensor configured to keep the oxygen partial pressure constant and detect the oxygen concentration from the current value flowing through the detection element used as the oxygen pump element, as described above, has been considered. The invention can also be applied to various types of air-fuel ratio sensors.

The above-mentioned gas diffusion t111 limited chamber is a chamber into which exhaust gas is introduced in a diffusion υ1 limited manner, and as described in the prior art section, two steel detection element parts are arranged facing each other with a gap between them. In this case, this gap becomes a gas diffusion restriction chamber, but other gas diffusion restriction chambers include, for example, a hollow spacer made of AJILzOa, spinel, )lusterite, steatite, zirconia, etc. between the detection element parts of 2118i. It is also possible to form a gas diffusion restriction section by sandwiching a hole in a part of this spacer to communicate the surrounding measurement gas atmosphere with the measurement gas chamber.

[Function 1] The present invention includes a first porous electrode that is included in the air-fuel ratio sensor as described above and is in direct contact with a measurement gas, and a gas diffusion method in which diffusion of the measurement gas is restricted. A constant current is supplied from the second porous electrode side to a detection element portion formed by laminating a second porous electrode in contact with the measurement gas in the II limit chamber on both sides of an oxygen ion conductive solid electrolyte, and The internal resistance is measured from the voltage generated between each electrode, and activation of the air-fuel ratio sensor is detected when the measured internal resistance is less than a predetermined value.

In other words, this means that when the air-fuel ratio sensor is not activated sufficiently, the internal resistance of the detection element is large, and when current is passed through the detection element, the voltage generated between the porous electrodes at both ends becomes much larger than normal. Therefore, activation of the air-fuel ratio sensor itself is determined by using this to detect activation of the detection element section.

Here, current is supplied to the detection element section from the second porous electrode side depending on the ratio of the oxygen gas partial pressure in the gas diffusion restriction chamber to the oxygen gas partial pressure in the surrounding measurement gas. This is to prevent large electromotive force from being generated. In other words, the diffusion of the measurement gas is restricted in the gas diffusion restriction chamber, and the M elemental gas partial pressure is lower than that of the surrounding measurement gas, which is thought to generate an electromotive force in the detection element. By supplying current from the porous electrode side of the electrode, oxygen in the surrounding measurement gas is pumped into the gas diffusion restriction chamber, thereby reducing the electromotive force generated in the detection element, that is, increasing the voltage generated between each electrode. This allows the internal resistance of the detection element portion to be detected satisfactorily.

Further, in order to suppress the electromotive force generated in the detection element section, it is desirable to keep the current supplied by the current supply means small. In other words, if this current value is increased, the oxygen gas partial pressure around the first porous electrode becomes too small, and a counter-electromotive force is generated, making it impossible to detect the internal resistance well. It is desirable to set it to a small value of about ten to several hundred EμA1.

Furthermore, even if the electromotive force generated in the detection element section is set to be as small as possible as described above, the partial pressure of oxygen gas on the first porous electrode side and the partial pressure of oxygen gas on the second porous electrode side,
It is not possible to match them completely, and voltages that are significantly different will occur, especially in the rich and lean air-fuel ratio ranges.
The resulting internal resistances will also have different values. Therefore,
It is preferable that the set value used for determining the activation of the air-fuel ratio sensor by the activation/off means is set in accordance with the operating state of the combustion engine until the air-fuel ratio sensor is activated.

For example, when performing air-fuel ratio control of an internal combustion engine using this type of air-fuel ratio sensor, the air-fuel ratio sensor is gradually activated as the internal combustion engine starts, and the internal combustion engine moves into an air-fuel ratio rich range by increasing the amount of fuel at startup. Therefore, it is preferable to set the internal resistance at the time of sensor activation in the air-fuel ratio ridge region in advance as the set value.

Specifically, for example, in the case of an internal combustion engine that is operated in a rich range of air excess ratio λ-0.8 at the time of startup due to fuel increase correction, the air-fuel ratio sensor is operated in advance under this operating condition to obtain the Set the time TW until the detection result reaches 90% of the activation time, then operate the internal combustion engine under the same operating conditions, and use the detection device to detect the detection element part at the corresponding interval Tw. All you have to do is measure the internal resistance and use the measurement result as the set value.

[Example 1 An embodiment of the present invention will be described below with reference to the drawings.

First, FIGS. 2 and 3 are exploded perspective views of activation detection in this embodiment.

As shown in FIGS. 2 and 3, the air-fuel ratio sensor of this embodiment includes an oxygen pump element 4 formed by laminating porous electrodes 2 and 3 on both sides of a solid electrolyte plate 1, and an oxygen pump element 4 formed by laminating porous electrodes 2 and 3 on both sides of a solid electrolyte plate 5. An oxygen concentration battery element 8 is formed by laminating porous electrodes 6 and 7 on the wafer, and is laminated between each of these detection elements 4 and 8. A spacer 9 in which a portion 9a is formed, a 'a bushy body 0 which is layered on the porous electrode 7 side of the oxygen concentration battery element 8,
It is made up of.

First, the spacer 9 is connected to the porous electrode 3 and the porous electrode 6.
The hollow portion 9a is used as the gas diffusion restriction chamber. The spacer 9 also has a hollow portion 9a so that surrounding measurement gas can be introduced into the hollow portion 9a.
[Notch bottoms are formed at three locations around 1 to serve as gas diffusion restriction portions.

Next, the shielding body 10 is a porous power supply 4 of the cable resistant & i light battery 8.
4i7 inside! ,! In order to use it as a quasi-oxygen source, the porous electrode 7 is removed from the external measuring gas. In addition, the porous electrode 7 covered with the shield 10 can leak oxygen generated inside the internal IJ (when used as an oxygen source) into the gas expansion chamber 9a and into the hollow part 9a. For example, the porous electrode 6 is connected to the porous insulator Z made of Flumica or the like through the through-toll.
It is connected to the 6 lead parts of. That is, the porous insulator Z1 through hole 1] and the lead portion 6 of the porous electrode 6
1 is formed as a leak resistance section, and oxygen generated in the porous electrode 7 can leak into the hollow portion Oa through this leak resistance section.

Furthermore, the electrode terminals of each porous electrode 2, 3.6.7 of the oxygen pump cord 4 and the oxygen concentration battery element 8 are
It is formed on the outer wall surface of 1-. However, since the porous power supply ff12 of the oxygen pump cord 4 is formed to be exposed to the outside, its lead portion 2. Q is used as an electrode terminal as it is, and the porous electrode 3 of the oxygen pump element 4 is laminated inside.
Alternatively, C in the porous electrodes 6 and 7 of the oxygen 'a' battery wood 8 is the lead portion 3i or 6 and 7. Q,
and electrode terminals 3t or 61 and 7t stacked W4 on the outer wall surface of the solid electrolyte plate 1 or the shield 10, respectively,
Is it formed by electrically connecting through 4-3h or G; t 6 h and 7h? 15 As shown in FIG. 1, the air-fuel ratio sensor of this embodiment configured as in 1 is sealed so that oxygen in the porous electrode layer 7 does not leak to the outside, and is fixed to fix the air-fuel ratio sensor 9S. It is attached to an exhaust pipe 17 of an internal combustion engine via a portion 15 and a threaded portion 16, and after its activation is detected by an activation detection circuit 20, it is operated by an air-fuel ratio detection circuit 30. In the top view, the lead portions and electrode terminals of each porous electrode are omitted to make it easier to understand the installation state of the air-fuel ratio sensor S.

The activation detection circuit 20 includes an operational amplifier OP1 for supplying a constant current (for example, 100 (μAl)) to the oxygen pump element 4 of the air-fuel ratio sensor S from the porous electrode 3 side serving as the first porous electrode. Constant current circuit 2 constructed using
1, a voltage detection circuit 22 configured using an operational amplifier OP2, which detects the voltage generated in the porous electrodes 2 and 3 at both ends of the oxygen pump cord 4, and this voltage detection circuit 2.
The voltage detected by 2 is the preset voltage EO.
When the following conditions occur, the activation of the air-fuel ratio sensor S is detected.
, an activation detection circuit 23 configured using a reductive amplifier OP3, which outputs activation detection signal No. 13, etc., which is switched by the activation detection signal output from the activation detection circuit 23, and the air-fuel ratio detection circuit 30 and the oxygen pump element 4 of the air-fuel ratio sensor S, analog switches 24 and 25 allow the air-fuel ratio detection circuit 30 to detect the air-fuel ratio;
It consists of

That is, the activation detection circuit 20 of this embodiment has a constant current circuit 21
A constant current is supplied from the porous electrode 2 side which is in contact with the surrounding gas to be measured on both sides of the oxygen pump element 4, and the voltage generated between each porous electrode 2 of the oxygen pump element 4 is detected by the voltage detection circuit. 22 to measure the internal resistance of the oxygen pump element 4, and the activation determination circuit 23 determines whether the measured value, that is, the voltage between the porous electrodes 2 and 3, is less than or equal to the set voltage Eo. Thus, the device is configured to determine that the internal resistance of the oxygen pump cord 4 is below a predetermined value and that the device is activated.

The constant current circuit 21, voltage detection circuit 22, and activation determination circuit 23 correspond to the current supply means, internal resistance measurement means, and activation determination means described above, respectively.

Further, the set voltage EO used in the activation detection circuit 23 will be explained in detail later.

Next, the air-fuel ratio detection circuit 3o detects activation of the air-fuel ratio sensor S by the activation detection circuit 20, and the analog switches 24 and 25 are switched in a direction opposite to that shown in the figure. connected to. In this air-fuel ratio detection circuit 30, a predetermined current is passed through the oxygen concentration cell element 8 to generate oxygen in the porous M electrode 7, and the generated anti-nan gas F[ and the hollow space serving as the measurement gas chamber are Part 9
Oxygen concentration battery element r8 according to the ratio with the oxygen gas partial pressure in a
The rW flow flowing through the Mi pump resistor 4 is bidirectionally controlled so that the voltage generated at both ends of the electrodes becomes constant, and the partial pressure of oxygen gas in the hollow part 9a becomes constant. It is configured to output the flow value as an air-fuel ratio signal.

That is, the air-fuel ratio detection circuit 30 applies a predetermined voltage Vb (V14) to the porous electrode 7 of the acid
For example, lo[V]) is applied, and a resistance R is generated to limit the current flowing to the other porous electrode 6 side to which the reference ffl pressure Va is applied, and the electrodes on both sides of the oxygen ILI light battery element 8, A buffer circuit 31 constituted by an operational amplifier OP4 detects the voltage boosted by the reference voltage V9 (VA, for example, 5V), and an operational amplifier OP5 amplifies the detection voltage output from the buffer circuit 31. The configured non-inverting amplifier circuit 32 and the non-inverting amplifier circuit 32
The detected voltage amplified by 1. /c, the system shown in FIG. 5 gradually decreases with a predetermined integral constant, and in the opposite case gradually increases with a predetermined integral constant! 2
Comparison/integration circuit 33 configured using an aperture amplifier OP6 that outputs a 1I voltage, etc., a buffer circuit configured using an aperture amplifier OP7 that outputs the reference voltage Va]
4th, buff 7+9! The reference voltage va from 't834 is applied to the porous electrode 3 on the hollow part 9a side of the oxygen pump cord 4, and this electrode 3 and the other porous electrode to which the control voltage from the comparison/integration circuit 33 is applied a current detection resistor R1 for detecting the current flowing between the resistor R1 and the resistor R1.
and an output circuit 35 constituted by an operational amplifier OP8, which outputs the voltage generated at the air-fuel ratio multiplied by @Vλ. The air-fuel ratio signal obtained by the air-fuel ratio detection circuit 30 changes continuously from a rich range to a lean range of the air-fuel ratio, as shown in FIG. 6, for example.

In the air-fuel ratio detection device configured as described above, activation of the air-fuel ratio sensor S is detected by the activation detection circuit 20, and the air-fuel ratio detection circuit 30 is connected to the air-fuel ratio sensor S by the activation detection circuit 20. Next, a method for setting the set voltage EO used to determine activation of the air-fuel ratio sensor S in the activation detection circuit 20 will be explained using an air-fuel ratio sensor used in an internal combustion engine as an example.

This set voltage EO corresponds to the set value of the internal resistance mentioned above, and first, the air-fuel ratio at the time of starting the internal combustion engine in which the air-fuel ratio sensor S is used is confirmed, and the internal combustion engine is started at that air-fuel ratio. is set experimentally after measuring the air-fuel ratio signal obtained by the air-fuel ratio circuit 30.

That is, Fig. 7 shows that the air-fuel ratio sensor S prepared as shown in the following table is attached to the exhaust pipe of a 4-cycle, 1.5F vertical internal combustion engine, and the internal combustion engine is rotated at a rotation speed of 1200 Cr. ,p,
s,], intake pipe internal pressure -500 [++vHG], exhaust temperature 170 ['C], and air-fuel ratio Δ/F: 12, the air-fuel ratio detection circuit 30 detects the air-fuel ratio sensor. Oxygen pump element 4 when S is operated simultaneously
This measurement data represents the pump current ip flowing in the pump current ip, the voltage p generated across it, and the voltage VS generated across the M element concentration battery element 8. This measurement data shows that the air-fuel ratio j7 sensor S is 90% activated. Taking the time Tw (in this case, 22 (sec)) until the air-fuel ratio detection circuit 30 is in the oven, the voltage generated across the oxygen pump element 4, which is 1q in the voltage detection circuit 22 when the air-fuel ratio detection circuit 30 is in the oven, is experimentally determined. , this value may be set as the set voltage Eo.

FIG. 8 shows the value of the internal resistance inside the oxygen pump element 4 calculated from the voltage generated across the oxygen pump element obtained through this experiment. In the case of the air-fuel ratio sensor S having the above configuration, Activation 9 determined from the above measurement data
The internal resistance Rp of the oxygen pump element 4 corresponding to the time TW (22 [5 ecl) to reach 0% is approximately 700 [Ω],
As the setting voltage, the current Iρ flowing through the oxygen pump 4 is set to 10
It can be seen that if it deviates from 0EμΔ], it becomes 70 [mV] from IDXR6. In this experiment, the air-fuel ratio sensor was heated with a heater.

In the above experimental example, when starting the internal combustion engine, the air-fuel ratio becomes rich due to normal fuel increase correction, and when determining whether to activate the air-fuel ratio sensor S, the internal combustion engine is operated under the above conditions. Therefore, this shows how to set the set voltage EO at this time. For example, when using the air-fuel ratio sensor S in a combustion equipment that is lean at the start of spinning, set the set voltage EO as follows. Bye.

That is, FIG. 9 shows the air-fuel ratio detection characteristics by the air-fuel ratio sensor S when atmospheric air is used as the exhaust gas when the air-fuel ratio is lean.
In this case, the time TW until the activation of the air-fuel ratio sensor reaches 90% is 30 [SeO3, so under this condition, the air-fuel ratio detection circuit 30 is activated when the activation detection circuit 2 is in the oven.
The voltage generated across the oxygen pump element 4 obtained by the zero voltage detection circuit 22 may be measured, and the voltage after 3Q [sec] may be set as the set voltage EO. In other words, based on this experiment, the internal resistance RD of the oxygen pump element 4 is calculated from the voltage generated across the terminals of the oxygen pump element 4 as shown in FIG.
0 [Ω], so if the current value from the constant current circuit 21 is 100 [μA1, the set voltage EO is 15-mV]
You can see that it is sufficient to do this. In this experiment, an air-fuel ratio sensor formed with the dimensions shown in the table above was used.
20±5'C (7) Atmospheric flow velocity 50 [1/m + n
] and heated the air-fuel ratio sensor with a pipette.

In the air-fuel ratio sensor activation detection device of this embodiment configured as described above, before the air-fuel ratio detection circuit 30 detects the air-fuel ratio, the air-fuel ratio sensor S is activated depending on the internal resistance of the oxygen pump element 4. When the air-fuel ratio sensor is activated, the air-fuel ratio can be detected directly using the air-fuel ratio detection circuit 30. Therefore, unlike in the past, the air-fuel ratio sensor is not able to detect the air-fuel ratio even though it is activated, and the air-fuel ratio of the internal combustion engine, etc. cannot be properly controlled. This makes it possible to always perform it well.

[Effects of the Invention] As detailed above, according to the air-fuel ratio sensor activation detection device of the present invention, it is possible to directly detect the activation from the internal resistance of the detection element portion constituting the air-fuel ratio sensor. Become. Therefore, activation of the air-fuel ratio sensor can be detected at speed Ab without causing a response delay, and air-fuel ratio control after activation of the air-fuel ratio sensor can be quickly executed.

[Brief explanation of drawings]

1 to 10 show an embodiment of the present invention, and a first embodiment of the present invention is shown in FIG.
The figure is a configuration diagram showing the configuration of the air-fuel ratio sensor and the activation detection circuit of this embodiment, FIG. 2 is a partially ruptured perspective view of the air-fuel ratio sensor, FIG. 3 is an exploded perspective view thereof, and FIG. An electric circuit diagram showing the air-fuel ratio detection circuit, FIG. 5 is a diagram showing the control signal of the oxygen pump element generated within the air-fuel ratio detection circuit, and FIG. 6 is a diagram showing the control signal of the oxygen pump element generated in the air-fuel ratio detection circuit. '7 air fuel ratio 13
Figure 7 shows the air-fuel ratio sensor.
The graph in FIG. 8 shows the activation state when operating in exhaust gas in the f-region, and the oxygen fA changes in the air-fuel ratio rich region as the main battery element air-fuel ratio sensor is activated! Figure 9 is a diagram showing the change in internal resistance of the 1!2 cable pump element. 10 is a diagram showing the activation state when the air-fuel ratio sensor is operated in the atmosphere, and FIG. 10 is a diagram showing the internal resistance of the oxygen pump element that changes as the air-fuel ratio sensor is activated in the atmosphere. . 1.5...Solid electrolyte plate 2.3.6.7...Porous electrode 4...Oxygen pump element 8...Oxygen concentration battery element 9...Spacer 9a...Hollow part (gas Diffusion restriction chamber) 20... Activation detection circuit 21... Constant current circuit 22... Voltage detection circuit 23... Activation determination circuit 30... Air-fuel ratio detection circuit

Claims (1)

[Claims] A pair of porous electrodes are laminated on both sides of an oxygen ion conductive solid electrolyte, the first porous electrode being in direct contact with the measurement gas,
An activation detection device for an air-fuel ratio sensor, comprising a detection element portion in which a second porous electrode is arranged to be in contact with a measurement gas in a gas diffusion restriction chamber in which diffusion of the measurement gas is restricted, a current supply means for supplying a predetermined current to the detection element section from the second porous electrode side; and a voltage generated between the first and second porous electrodes due to the current supply from the current supply means. an internal resistance measuring means for measuring an internal resistance of the detecting element; and when the internal resistance of the detecting element measured by the internal resistance measuring means is less than or equal to a preset value, activation of the air-fuel ratio sensor; An activation detection device for an air-fuel ratio sensor, comprising: activation determination means for detecting;