JPS61122556A - Electric energy controller of heater for oxygen concentration sensor - Google Patents

Abstract

PURPOSE:To control an oxygen concentration sensor to constant temperature and to detect oxygen concentration accurately by controlling electric power supplied to a heater for heating the oxygen concentration sensor with the output based upon impedance and the concentration of the residual oxygen in exhaust gas. CONSTITUTION:The oxygen concentration sensor 5 is fitted to the exhaust pipe 3 of an internal combustion engine 1. The oxygen concentration sensor 5 consists of a detecting element 1 and the heater 12. Then a specific DC voltage and an AC voltage are applied from a voltage applying circuit 19 to the detecting element 11 to detect a current corresponding to the oxygen concentration. This current is inputted to an impedance detecting circuit 23 and a low-pass filter 25. The output Vh of this circuit 23 reflects the temperature of the element 11, varies with the concentration of the residual oxygen in the exhaust gas, so it is corrected with the output Vi of the low- pass filter 25, i.e. oxygen concentration and electric power is supplied to the heater 12. Thus, the oxygen concentration sensor is controlled to the constant temperature, so the oxygen concentration is detected accurately and a wasteful consumption of electric power is eliminated.

Description

[Detailed Description of the Invention] 11L1 Disturbance [Industrial Application Field] The present invention relates to a power consumption control device for a heater for an oxygen concentration sensor, and more specifically, a device for controlling the amount of power of a heater for an oxygen concentration sensor. The present invention relates to a power amount control device for a heater for an oxygen concentration sensor that controls the amount of power supplied to a heater provided in the oxygen concentration sensor.

[Prior Art] In recent years, oxygen concentration sensors using materials such as zirconia or titania have come into practical use. With the oxygen concentration sensor activated,
There is also a so-called limiting current type oxygen concentration sensor that measures the limiting current with respect to the voltage applied between electrodes. The limiting current flowing through the oxygen concentration sensor detects the oxygen concentration by utilizing the fact that the amount of oxygen that diffuses through the small holes or gaps formed in the oxygen concentration sensor is proportional to the oxygen concentration of the gas being measured. be.

In order to detect oxygen concentration using such a limiting current, the temperature of the oxygen concentration sensor must be set to a predetermined temperature, for example, 650℃.
It must be done at a temperature of about ℃ or higher. On the other hand, considering the durability of the oxygen concentration sensor, excessive heating may cause problems such as disconnection of the heater or destruction of the detection element. It is necessary to control the amount of power supplied to the heater so that the temperature can be maintained within the 750°C range.

Therefore, for example, in a limiting current type oxygen concentration sensor such as ``Method and Apparatus for Measuring the Concentration of a Limiting Current Sonde or Oxygen Sonde'' disclosed in Japanese Patent Application Laid-Open No. 57-187646, a direct current voltage for detecting the oxygen concentration is used. By applying a voltage that is a superposition of the voltage and a high-frequency alternating current voltage for detecting the impedance of the oxygen concentration sensor without being affected by the oxygen concentration, the oxygen concentration is detected from the average value of the output current, and the amplitude of the output current is A method of detecting the impedance of an oxygen concentration sensor has been proposed. In this idea, since the impedance of the oxygen concentration sensor depends on the temperature of the element, the oxygen concentration It has been considered to control the temperature of the sensor.

[Problems to be Solved by the Invention] Such an oxygen concentration sensor is installed in the exhaust gas of an internal combustion engine to detect the oxygen concentration in the exhaust gas and perform various controls, such as internal combustion control.
When performing normal air-fuel ratio control to keep the open air-fuel ratio at the stoichiometric air-fuel ratio or lean burn control aimed at improving fuel efficiency,
The following problems existed.

Since the exhaust gas temperature of the internal combustion engine changes depending on the operating state of the internal combustion engine, it is not possible to always maintain the temperature of the M concentration sensor at 650° C. or higher just by heating with the exhaust gas. Therefore, the oxygen concentration sensor is provided with a heater for heating, but it is not preferable for the durability of the oxygen concentration sensor that the temperature of the oxygen concentration sensor increases excessively due to heating by the heater. In addition, it is difficult to provide a large-capacity heater to the oxygen concentration sensor, which requires miniaturization, because it is mounted on a vehicle, and in reality, it is necessary to avoid putting unnecessary burden on the battery. There was also the problem. Therefore, the amount of electricity supplied to the heater is precisely controlled to maintain the temperature of the oxygen concentration sensor at an appropriate temperature, for example, around 650 degrees Celsius. There has been a problem in that an error occurs in the detection of temperature, and it may not be possible to ensure a sufficient temperature.

Therefore, the present inventors have developed a power amount control device for a heater for an oxygen concentration sensor that can accurately control the temperature of an oxygen concentration sensor equipped with a small heater that can be mounted on a vehicle, and that can be used for various controls of an internal combustion engine. Through repeated research with the aim of providing
The present invention was completed based on the finding that the impedance of the oxygen sensor, which was supposed to be able to measure regardless of oxygen concentration by applying a high-frequency alternating current, is affected by oxygen concentration.

[Means for solving the problems] The means of the present invention taken to solve the above problems, as shown in FIG. 1, have the following configuration.

That is, an oxygen concentration sensor heating heater M3 provided in an oxygen concentration sensor M2 provided in the exhaust system of the internal combustion engine M1 to detect the oxygen concentration in the exhaust gas, and a heater M3 for heating the oxygen concentration sensor that is provided in the oxygen concentration sensor M2 that is installed in the exhaust system of the internal combustion engine M1 and detects the oxygen concentration in the exhaust gas; temperature detection means M4 that detects the temperature of the oxygen concentration sensor M2 using the impedance of the oxygen concentration sensor; and an amount of electric power that controls the amount of electric power supplied to the oxygen sensor heater M3 based on the detected temperature. Control means M
5. In the power amount control device for a heater for an oxygen concentration sensor, 5, the predistribution power crushing control means M5 corrects the amount of power to be supplied based on the residual oxygen m degrees in the exhaust gas of the internal combustion engine M1. This is the configuration of a power amount control device for a heater for an oxygen concentration sensor, which is characterized in that it is configured to:

Here, the oxygen concentration sensor M2 may be of a limit IN flow type, but any other oxygen concentration sensor that can detect the a1 degree by the impedance of the sensor itself can be used. Further, as the heater M3 provided in the oxygen ma sensor M2, various heaters such as a PTC heater or a ceramic heater can be used in addition to a normal hot wire heater.

The temperature detection means M4 is configured to detect the temperature of the oxygen concentration sensor M2 by measuring the impedance of the oxygen concentration sensor M2. As a device for measuring the impedance of the current flowing through the concentration sensor M2 from the amplitude thereof, a configuration in which an AC voltage output section, a bypass filter, and a filter are combined can be considered.・
The power amount control means M5 controls the amount of power supplied to the heater M3 according to the output of the concentration detection means M4, and here, the power amount control means M5 further controls the amount of power supplied to the heater M3 in accordance with the output of the concentration detection means M4.
Ir! 1 to correct this power amount. The power amount control means M5 may have a discrete circuit structure separate from the temperature detection means M4, or may be constructed using a microcomputer together with the temperature detection means M4 or alone.

It is accurate to correct the power amount based on the residual oxygen, si, in the exhaust gas of the internal combustion engine M1 by the power amount control means M5 using the oxygen concentration detected by the oxygen concentration sensor M2, but the circuit configuration is simplified. The remaining oxygen concentration in the exhaust gas is determined based on the operating status of the internal combustion engine M1, such as when a fuel cut is in progress (the air-fuel ratio is lean) or when the throttle valve is fully open (the air-fuel ratio is normally rich due to a full-open increase). It is also suitable to be configured to estimate. Further, the oxygen concentration may be estimated based on the operating state of the internal combustion engine M1 determined from the rotational speed, intake air amount, intake pipe pressure, etc. of the internal combustion engine M1.

[Function] The power amount control device for the oxygen concentration sensor heater of the present invention having the above configuration detects the temperature of the oxygen am sensor M2'' using the impedance of the oxygen concentration sensor M2, and based on this, the oxygen concentration sensor Heater M3 provided in M2
The temperature of the oxygen concentration sensor M2 is controlled by controlling the amount of electric power supplied to the internal combustion engine 1 by the electric power amount control means M5.
m[The amount of power supplied to heater M3 is corrected based on the residual oxygen concentration in the exhaust gas of IMl.

FIG. 2 is a graph showing the relationship between the applied voltage and the current flowing through the oxygen concentration sensor M2 when a limiting current type sensor is used as the oxygen concentration sensor M2.

As shown in the figure, the limiting current changes depending on the oxygen concentration. The solid line Z represents the case where the temperature of the oxygen concentration sensor is 750°C.
The broken line B represents the case where the temperature of the oxygen concentration sensor is 650°C. Therefore, it can be seen that in order to set the voltage applied to the oxygen concentration sensor M2 to be approximately 0.6■ and to detect the oxygen concentration from the limiting current, it is necessary to maintain the temperature of the oxygen concentration sensor M2 at at least about 650°C. .

On the other hand, FIG. 3 is a graph showing the complex impedance of the oxygen concentration sensor M2 with respect to the applied AC voltage. In the figure, the high frequency side A-B is a region that is generally considered not to be affected by oxygen concentration, and the low frequency side (here, 500H
(below z) is considered to be a region affected by oxygen concentration.

The solid line R shows the case where the oxygen concentration is 10%, and the broken line H shows the same 2%.
It shows the complex impedance in the case of .

As can be seen from Figure 3, even when a high frequency voltage of 500 Hz or more is applied, the oxygen ml! ! :Sensor M2
It cannot be said that the influence of oxygen concentration on the impedance of The temperature of sensor M2 will change.

Therefore, when the oxygen concentration sensor M2 is installed in the exhaust gas of the internal combustion engine M1, the temperature of the oxygen concentration sensor M2 changes depending on the fluctuation of the air-fuel ratio of the internal combustion*m, and in some cases, the residual oxygen concentration using a limiting current may be It is conceivable that accurate measurements may not be possible.

In contrast, the power amount control device for the oxygen concentration sensor heater of the present invention corrects the amount of power supplied to the heater based on the residual oxygen concentration in the exhaust gas of the internal combustion engine M1. It works to precisely control the temperature of the exhaust gas regardless of the condition of the exhaust gas.

[Example] Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 5 is a schematic diagram of a power amount control device for a heater for an oxygen a degree sensor according to the present invention.

In the figure, 1 is an internal combustion engine, 3 is an exhaust pipe of the internal combustion engine 1,
5 is an oxygen concentration sensor with a heater attached to the exhaust pipe 3; 7 is operated by receiving power from a battery 9, and detects the oxygen concentration in the exhaust gas using the oxygen concentration sensor 5; Each represents an electronic control circuit that performs temperature control.

Although the structure of the oxygen concentration sensor 5 is schematically shown in the figure, it includes a zirconia-based limiting current type detection element 11 that detects the oxygen concentration in the exhaust gas of the internal combustion engine 1, and a heating element 11 that increases the temperature of the detection element 11. A heater 12 for use is integrated.

The electronic control circuit 7 includes a detection element 11 of the oxygen concentration sensor 5.
A voltage application circuit 19 is provided for applying a predetermined voltage, for example, a voltage having an AC component amplitude of 0.2VI) p5KHz superimposed on a DC component O16. The current flowing through the detection element 11 in accordance with the applied voltage and oxygen concentration is converted into a voltage signal by flowing through the current detection resistor R1, and is passed through an impedance detection circuit 23 consisting of a bypass filter and an integrator, and a low-pass filter 25. It is taken into account. The output vh of the impedance detection circuit 23 is the detection element 1
1, but since the impedance also changes depending on the residual oxygen concentration in the exhaust gas, it is corrected according to the output V1 of the low-pass filter 25, that is, the oxygen concentration, and the amount of power supplied to the heater 12 is controlled. It turns out. Note that the output v1 of the low-pass filter 25 is used elsewhere as a lean/rich signal for detecting the air-fuel ratio of the internal combustion engine 1.

The comparator 26 and the power transistor Tr control the above-mentioned correction and power amount, and can have a configuration as shown in the circuit diagram of FIG. 6, for example. In the figure, 32
is a correction circuit that corrects the output vh of the impedance detection circuit 23 using the output v1 of the low-pass filter 25, and outputs a signal VH after correction based on the oxygen concentration. This correction by the output v1 of the low-pass filter 25 is to correct the impedance of the detection element 11 (corresponding to the signal vh) according to the residual oxygen concentration in the exhaust gas of the internal combustion engine 1, as shown in the graph of FIG. low pass filter 25
In adding the addition coefficient α determined by the output signal v1 of J to the output signal vh of the impedance detection circuit 23, J:
That is, VH=Vh+Vα, and a signal V)-1 that exactly corresponds to the temperature of the detection element 11 is output. Therefore, the signal Vl-( has been corrected for the deviation due to oxygen 111 degrees,
Since it accurately reflects the temperature of the oxygen concentration sensor 5, it is input to one input terminal of the comparator 33, and compared with a preset comparison value, such as a reference voltage V ref, to control the power transistor Tr. Used for on/off control. Note that R2 is a resistor that limits the base current of the power transistor 7r.

In the above example, the reference voltage V ref is set to correspond to 700° C. as the temperature of the detection element 11 of the oxygen concentration sensor 5, so the current flowing through the heater 12 is controlled by turning on and off the power transistor Tr. The temperature of the oxygen concentration sensor 5 can be accurately set to 700°C.

Therefore, according to this embodiment, the temperature of the oxygen concentration sensor 5 can be controlled to be constant regardless of the residual oxygen concentration in the exhaust gas of the internal combustion engine rlA1, and the limiting current type oxygen concentration sensor 5 can be used for accurate measurement. It is possible to maintain the temperature at a suitable temperature (here, 700° C.) from the viewpoint of durability. As a result,
It has become possible to accurately detect the oxygen concentration in the exhaust gas of the internal combustion engine 1, and it has also become possible to control the air-fuel ratio of the internal combustion engine 1 with great precision.

2. It is also conceivable that the comparator 26 in the above embodiment has a configuration as shown in FIG. In the circuit configuration of the comparator 26' shown in FIG.
Addition ff1 determined by the graph of FIG. 9 for ref
Vα and its output signal vref′ is sent to comparator 3.
It is used for comparison with the signal vh at 3'. Therefore,
Even if the comparator 26- in FIG. 8 is used, the same effect as in the embodiment described above can be obtained.

Next, a second embodiment of the present invention will be described. FIG. 10 is a schematic diagram of a system for controlling the air-fuel ratio of an internal combustion engine using a power amount control device for a heater for an oxygen concentration sensor according to an embodiment.

In the figure, 51 is an engine, 52 is a piston, 53 is a cylinder, 54 is a cylinder head, an exhaust manifold 56 is attached to an exhaust boat 55 of each cylinder in the cylinder head 54, and an intake boat 57 is attached to each cylinder in the cylinder head 54.
An intake manifold 58 is connected to each of the intake manifolds 58. Further, the intake manifold 58 is provided with a surge tank 59 for preventing pulsation of intake air.
An intake pressure sensor 60 is provided to detect the intake pressure.

Next, 61 is a throttle valve that controls the amount of intake air sent to each cylinder via the surge tank 59, 63 is an intake temperature sensor that detects the intake air temperature, and the throttle valve 61 has a The throttle valve opening sensor and the engine 51 output a signal according to the
A throttle position sensor 64 is directly connected to the idle switch, which is turned on when the engine is idling. Further, 65 is an oxygen concentration sensor attached to the exhaust manifold 56 and includes a detection element for detecting the oxygen concentration in the exhaust gas and a heater for heating, and 66 is a water temperature sensor for detecting the temperature of the cooling water of the engine 51.

67 is a distributor that applies a high voltage output from the igniter 69 to the spark plug 68 of the engine 51 at a predetermined timing, and 70 is a rotation speed sensor that is attached to the distributor 67 and generates a pulse signal corresponding to the rotation speed of the engine 51. each represents.

The intake pressure sensor 60. Intake temperature sensor 63: Throttle position sensor 64. Various detection signals from the oxygen concentration sensor 65, water temperature sensor 66, and rotation speed sensor 70 are output to a control circuit 75, and the control circuit 75 controls the fuel injection amount of the fuel injection valve 76 and the spark plug 6 based on the detection signals.
Various control processes such as ignition timing control of 8 or control of the heater of the oxygen concentration sensor 65 are executed.

Next, the configuration of the above-mentioned control circuit 75 will be explained with reference to FIG. First, reference numeral 81 denotes a medium voltage control circuit that synthesizes and applies a DC voltage Vdc for oxygen concentration detection and an AC voltage Vac for impedance detection of the detection element 65a to the detection element 65a of the oxygen concentration sensor 65. 82 is a resistor for detecting the current flowing through the detection element 65a; 83
is an amplifier circuit for amplifying the voltage drop across the resistor 82 by a predetermined factor. 84 is a detection circuit that extracts only the AC component from the output of the amplifier circuit 83 and detects the impedance of the detection element 65a, that is, the temperature of the detection element 65a,
It consists of a bypass filter and a rectifier. On the other hand, 85 is a low-pass filter that extracts only the DC component from the output of the amplifier circuit 83 and detects the residual oxygen concentration in the exhaust gas from the limit current of the detection element 65a. Here, the output signal of the detection circuit 84 is assumed to be an AC detection signal Vr, and the output signal of the low-pass filter 85 is assumed to be a DC detection signal Is.

Further, reference numeral 94 indicates an output signal from the amplifier circuit 83, that is, an analog signal corresponding to the oxygen concentration in the exhaust gas, and an intake pressure sensor 60. Intake temperature sensor 63. Throttle position sensor 64. This is an A/D conversion input circuit that receives an analog signal detected by the water temperature sensor 66 or the like and converts it into a digital signal. Further, 95 represents a drive circuit controlled by a control signal calculated and outputted by the microcomputer 97, which drives the fuel injection valve 76 and injects the desired amount of fuel calculated by the microcomputer 97 into the engine 51. This is a circuit that outputs a drive signal to be supplied to the motor. The igniter 69 is controlled by a microcomputer 97 to output high voltage to the distributor 67 at a predetermined timing.

Next, 98 is a heater energization control circuit for controlling the power supplied to the heater 65b of the oxygen concentration sensor 65, and controls the energization from the heater power source 99 in accordance with a control signal from the microcomputer 97. . Also, heater 6
The voltage value ■n applied to the heater 65b and the current value ■n flowing through the heater 65b are determined by the A/D conversion input circuit 94, the former directly, and the latter by using the voltage conversion resistor 101.
It is configured so that it can be input to the microcomputer 97 and read by the microcomputer 97.

In the Dim cycle wi75 of this embodiment configured as above, various controls such as fuel injection amount control, ignition timing control, and heater control of the oxygen concentration sensor 65 are executed as described above. However, below, the heater control of the oxygen concentration sensor, which is the main control process related to the present invention, will be explained in detail according to the heater control routine shown in FIG.

The heater power control routine shown in FIG.
0, first, in step 200, various parameters such as output signals from each sensor and detection circuit of the engine 51 are read.

Here, the rotation speed Ne of the engine 51, the intake pipe pressure Pn
+, DC detection voltage Is of the detection element 65a of the oxygen concentration sensor 65 corresponding to the residual oxygen concentration in the exhaust pipe 56, oxygen concentration sensor 65 corresponding to the temperature of the oxygen concentration sensor 65
Various parameters such as the AC detection voltage Vr for detecting the impedance of the detection element 65a, the applied voltage Vn1 of the heater 65b, and the current In flowing through the heater 65b are read.

In the following step 210, it is determined whether the AC detection signal vr read in step 200 is greater than or equal to a predetermined value Vrer. As mentioned above, the AC detection signal ■r corresponds to the temperature of the detection element 65a, and here
aVref corresponds to approximately 700° C. as the temperature of the detection element 65a. The judgment at step 210 is r Y E
If S J, the process proceeds to 220, where the first correction coefficient Pα for correcting the amount of power supplied to the heater 65b is set to 0.0
1, and the determination at step 210 is rNOJ.
That is, if the detection element temperature is less than 700° C., the process proceeds to step 230, increases the first correction coefficient Pα by 0301, and proceeds to the next step 240.

In step 240, a second correction coefficient Pβ for correcting the amount of power supplied to the heater 65b is calculated from the DC detection signal (S) corresponding to the residual oxygen concentration of the exhaust gas using a map.The correction coefficient Pβ is The map is determined, for example, from the graph shown in Figure 13, and is determined to be a small value below 1 if the DC detection signal Is, that is, the residual oxygen concentration is large, and approximately 1 if the residual 'WJ elementary concentration is small. .

The process then proceeds to step 260, where the electric power ff1 is obtained when electric power is supplied to the heater 65b with a duty of 100%.
PA is calculated from the voltage vn applied to the heater 65b and its current In read in step 200.

In the following step 270, from the engine 51 rotation speed Ne and intake pipe pressure pv+ read in the same step 200,
From a map such as the one shown in FIG. 14, the heater 65b
A process is performed to determine the target power PB to be supplied to the target power PB.

This is a map set based on the fact that the exhaust gas temperature of the engine 51 is determined to some extent from the operating state of the engine 51. Naturally, when the intake pipe pressure pm is large or when the engine speed Ne is large, the exhaust gas temperature of the engine 51 The amount of fuel injected into the heater 65b increases, the exhaust gas temperature rises, and the detection element 65a is heated by the exhaust gas.
On the other hand, when the engine speed Ne is low or the intake pipe pressure pm is low, the exhaust temperature decreases and the detection element cannot be heated, so the power supplied to the heater 65b is increased. It is set.

In the following step 280, the first correction amount Pα learned in steps 220 and 230, the second correction layer Pβ obtained in step 240, and the step 260
, 270, the amount of power supplied to the heater 65b according to the following equation (1),
Here, the duty D is calculated.

D-PBXPαXPβ/PA (1) In step 290, the duty D obtained in step 280 is
A pulse signal of
A process for controlling the temperature is performed, and the process exits to NEXT to end this control routine.

In this embodiment configured as described above, the amount of electric power supplied to the heater 65b of the oxygen concentration sensor 65 is controlled by the impedance of the detection element 65a (signal ■r), and the amount of power in the exhaust gas detected by the detection element 65a is Corrected by the residual oxygen concentration, the temperature of the detection element 65a is always kept at 700.
Control is in place to maintain the temperature at ℃. Therefore, the temperature of the oxygen concentration sensor 65 can be maintained at a temperature sufficient for detecting the oxygen concentration without causing wasteful consumption of power.
The oxygen concentration in the exhaust gas of the engine 51 can be detected accurately. Furthermore, since the temperature of the oxygen concentration sensor 65 can be accurately controlled, excessive power is not supplied, and the durability of the oxygen concentration sensor 65 in use is improved.

In this embodiment, the control circuit 75 includes a microcomputer 97.
is also used to perform other controls of the engine 51, such as air-fuel ratio control and ignition timing υJail, making it possible to reduce the total number of parts. In addition, reliability can be improved by being able to be configured to be checked by a self-diagnosis program.

Although several embodiments of the present invention have been described above, the present invention is not equally limited to these embodiments, and can be implemented in various forms without departing from the gist of the present invention. Of course.

LlL Calculation 1- As detailed above, according to the power amount control device for the oxygen concentration sensor heater of the present invention, the temperature of the oxygen concentration sensor can be controlled to be constant without being affected by the residual oxygen concentration. This provides an excellent effect in that the oxygen concentration can be detected extremely accurately. Furthermore, the durability of the oxygen concentration sensor can be improved without causing unnecessary consumption of power.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is a graph showing the output characteristics of a limiting current type oxygen concentration sensor, Fig. 3 is a graph showing the complex impedance of the oxygen concentration sensor, and Fig. 4 is a graph showing the oxygen concentration sensor. FIG. 5 is a schematic configuration diagram of the power layer control device for the heater for the oxygen 81 degree sensor according to the first embodiment of the present invention, and FIG. 7 is a graph for determining the addition amount Vα, FIG. 8 is a configuration diagram showing another example of the configuration of the comparator, FIG. 9 is another graph for determining the addition amount vα, and FIG. 10 is a graph for calculating the addition amount Vα. A schematic configuration diagram of a system for controlling the air-fuel ratio of an internal combustion engine as a second embodiment of the invention, FIG. 11 is a block diagram centered on the control circuit 75, FIG. 12 is a flowchart showing an example of the control, and FIG. 13 is a graph for determining the second correction coefficient Pβ, and FIG. 14 is a map for determining the target power ff1PB. 1... Internal combustion engine 3... Exhaust pipe 5.65... Oxygen sensor 11.65a... Detection element 12.65b... Heater 23... Impedance detection circuit 25.85... Low-pass filter 26... Comparator 51... Engine 60... Intake pressure sensor 70... Rotation speed sensor 75... Control circuit 84... Detection circuit 97... To microcomputer Agent Patent attorney Establishment period 1
Figure 2 Figure 3 ■ Z(n) Figure 4 9 Rip 1 To, Noha branch /”/;ノ Figure 5 23... In C-Dance Suzuyo circuit also
25 -Roll filter 26- Figure 6, Figure 7, Figure 13, Figure 14

Claims (1)

[Scope of Claims] 1. A heater for heating an oxygen concentration sensor included in an oxygen concentration sensor installed in an exhaust system of an internal combustion engine to detect oxygen concentration in exhaust gas, and outputting a signal according to the oxygen concentration in exhaust gas. temperature detection means for detecting the temperature of the oxygen concentration sensor using the impedance of the oxygen concentration sensor; and power amount control for controlling the amount of power supplied to the heater for heating the oxygen sensor based on the detected temperature. In the power amount control device for a heater for an oxygen concentration sensor, the power amount control means is configured to correct the amount of power to be supplied based on the residual oxygen concentration in the exhaust gas of the internal combustion engine. A power amount control device for a heater for an oxygen concentration sensor, characterized in that: 2. The temperature detection means is configured to apply an AC voltage to the oxygen concentration sensor, extract the AC impedance of the oxygen concentration sensor as a signal, and detect the temperature of the oxygen concentration sensor from this signal; It is configured to compare the AC impedance signal with a predetermined reference value to control the amount of power supplied to the oxygen concentration sensor, and further correct the amount of power based on the residual oxygen concentration in the exhaust gas of the internal combustion engine. 2. The power amount control device for an oxygen concentration sensor heater according to claim 1, wherein said adjustment is performed by correcting either said alternating current impedance signal or said reference value. 3. Power amount control of the oxygen concentration sensor heater according to claim 1 or 2, wherein the power amount is corrected based on the residual oxygen concentration in the exhaust gas of the internal combustion engine detected by the oxygen concentration sensor. Device. 4. The power amount control device for an oxygen concentration sensor heater according to claim 1 or 2, wherein the residual oxygen concentration used for correcting the power amount is estimated based on the operating state of the internal combustion engine.