JPH03189350A - Heater control unit for oxygen sensor - Google Patents

Abstract

PURPOSE:To enable it to cope with temperature abnormality in an oxygen sensor and anything unusual in an oxygen sensor output value due to desired resistance value abnormality by judging it to be something wrong in the desired resistance value when such a state that heater supplied power has come out of the specified range is continued as long as the specified period. CONSTITUTION:A control means M4 controls the supplied power of a heater M5 so as to make a heater resistance value of this heater M5 for temperature control of an oxygen sensor M1 come to the desired resistance value. A desired value renewal means M6 renews the desired resistance value so as to make the supplied power for the heater M5 at time of the specified driving state of an internal combustion engine M2 come to the specified standard power. A power supply judging means M7 judges whether the power supply for the heater M5 is within the specified range or not, while a desired resistance value abnormal judging means M8 judges something wrong in the desired resistance value when such a state that power supply to the heater M5 is out of the specified range is continued as long as the specified period. Consequently, it is judged as abnormality in the desired resistance value when the desired resistance value largely differs from the request value because of replacement of the oxygen sensor M1 or battery change or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for controlling the power supplied to a temperature control heater for maintaining an oxygen sensor at an appropriate temperature.

[Conventional technology]

Oxygen sensors that detect the oxygen concentration in the exhaust gas of internal combustion engines generally do not output accurate values unless the sensor+j temperature is maintained at an appropriate temperature. In particular, oxygen sensors using N-type oxide semiconductors (e.g., titania-type oxygen sensors)
The temperature dependence of the output value is large.
(See B)) Therefore, it is necessary to control the oxygen sensor temperature more strictly.

Therefore, conventionally, the resistance value of the heater installed in the oxygen sensor was 11! Using the fact that it represents the temperature of the elementary temperature,
It has been considered to control the electric power supplied to the heater so that the heater resistance value becomes a predetermined target resistance value.

However, since the resistance value of the heater itself varies depending on individual differences and changes over time, even if the heater resistance value reaches the target resistance value, the temperature will vary. Therefore, the applicant has proposed that the heater resistance value be controlled to a predetermined target resistance value, and that the power supplied to the heater when the internal combustion engine is in a predetermined operating state is detected, and that the supplied power is the standard value in the operating state. By updating the target resistance value so that the electric power ).

[Problem to be solved by the invention]

However, is the target resistance value updated to eliminate the effects of individual differences in heater resistance values and changes over time? Since it is stored in the Tsubu RAM, the value will be lost when the battery is replaced, and the target resistance value will be a different value from the value that has been updated up to now during operation immediately after that. In particular, when using an oxygen sensor that has undergone advanced aging, the update of the target resistance value is more advanced, so the above-mentioned problem becomes more serious.

In addition, even if the battery is not replaced, even if the oxygen sensor that has deteriorated over time is replaced with a new oxygen sensor while the battery is connected, the currently memorized target resistance value is not multiplied by the required value. It becomes something separate.

When such an abnormality in the target resistance value occurs, the oxygen sensor g
Since the temperature becomes abnormal, the oxygen sensor outputs an incorrect output value.

The heater tA control device previously filed by the present applicant did not detect abnormalities in the target resistance value, so it was difficult to deal with abnormalities such as the above-mentioned oxygen sensor temperature abnormality and oxygen sensor output value abnormality. The problem was that it couldn't be done.

Therefore, the present invention has been made in view of the above points, and the present invention determines that the target resistance value is abnormal when the heater supply power continues to be outside the predetermined range for a predetermined period. The purpose of the present invention is to make it possible to deal with an abnormal temperature of an oxygen sensor or an abnormal output value of an oxygen sensor that occurs due to the above.

[Means to solve the problem]

FIG. 1 includes a diagram of the principle of the device of the present invention.

In the figure, an oxygen sensor M1 detects the oxygen concentration in the exhaust gas of an internal combustion engine M2, and an air-fuel ratio υ control means M3 detects an oxygen sensor 4J.
The air-fuel ratio of internal combustion engine M2 is determined using the detection signal of M1.

The $1vs means M4 controls the heater M5 so that the heater resistance value of the heater M5 for temperature control of the oxygen sensor M1 becomes the target resistance value.
The power supply of 5 is tsm.

The target resistance value updating means M6 updates the internal combustion B! The target resistance value is updated so that the power supplied to the heater M5 during a predetermined operating state of the leapfrog becomes a predetermined standard power.

The supplied power determining means M7 determines whether the supplied power of the heater M5 is within a predetermined range.

The target resistance value abnormality determining means M8 determines that the target resistance value is abnormal when the power supplied to the heater continues to be outside the predetermined range for a predetermined period of time.

[Effect]

In the present invention, if the target resistance value of the control means M4 is significantly different from the required value due to replacement of the oxygen sensor M1 or battery replacement, etc., the state in which the power supplied to the heater M5 is outside the predetermined range continues for more than a predetermined value. In addition, when the target resistance value is appropriate, the state in which the supplied power is outside the predetermined range will not continue, so the supplied power determining means M7 and the target resistance value abnormality i1 constant means M8 can be adjusted. Accordingly, it is possible to determine whether the target resistance value is abnormal.

〔Example〕

FIG. 2 shows a configuration diagram of an embodiment of a gasoline engine to which the device of the present invention is applied.

In the figure, 1 is the gasoline engine body, 2 is the piston, and 3
is a spark plug, 4 is an exhaust manifold, 5 is an intake manifold, 6 is a surge tank that absorbs the pulsation of intake air, 7 is a throttle valve that adjusts the amount of intake air,
8 is an air flow meter that measures the amount of intake air. The exhaust manifold 4 is provided with an oxygen sensor 9 that detects the residual oxygen concentration in the exhaust gas, and the intake manifold 5 is provided with a fuel injection valve 10 that injects fuel into the intake air of the gasoline engine body 1. Intake temperature sensor +J11
detects the temperature of intake air, the throttle sensor 12 detects the opening degree of the throttle valve 70, and the water temperature sensor 13 detects the temperature of gasoline engine cooling water.

Further, the igniter 16 generates the high voltage necessary for ignition and supplies it to the distributor 17, and the distributor 17 distributes the high voltage to the spark plugs of each cylinder in conjunction with the rotation of the crankshaft (f not shown). supply The rotation angle sensor 18 sends a rotation angle signal j3NE of 24 pulses per 1 rotation of the distributor 17, that is, 2 rotations of the crankshaft.
The cylinder discrimination sensor 19 outputs
A rotation detection signal G of 1 pulse is output for each rotation of 7.

20 is an electric PTSM circuit, 21 is a key switch, and 22 is a starter motor.

The electronic control circuit 20 has a configuration shown in FIG. 3, and includes a central processing unit (CPLI) 30, a read-only memory (ROM) 31 that stores processing programs, and a random access memory (ROM) used as a work area. RAM) 32 and M33 to the backup R that retains data even after power is stopped.
It consists of an A/D converter 34 with a multiplexer function, a 110 interface 35 with a balance function, and a backup circuit 36 that performs backup Il-.
These are interconnected by a pass line 37.

The A/D converter 34 receives the air flow rate signal from the air flow meter 8, the intake air temperature signal from the intake air temperature sensor 11, the water temperature signal from the water temperature sensor 13, and the heater resistance detector 23 built into the oxygen sensor 9. Each signal is digitized by being supplied with a resistance value detection signal, and these digital signals are read by the CPU 30. Also, the I10 interface 35 has an s's sensor 9. Throttle sensor+)12. [1li1 rotation angle sensor 18. Signals from the cylinder discrimination sensor 19 and the key switch 21 are input,
Each signal is read by CPU 30.

The CPυ30 calculates the ignition timing, fuel injection amount, and energization pulse duty ratio of the oxygen sensor heater based on the detection data of each sensor, and the obtained ignition signal, fuel injection signal 0 energization pulse signal is 110 Interno Ace 35
Through the igniter 16, fuel injection valve 10.1%! It is supplied to each element sensor heater 24.

Next, the control of 70 grams according to an embodiment of the present invention will be explained.

Figure 4 shows the oxygen sensor heater ill ti) 51! L
A flowchart of the process is shown below. This the routine is 16
It is assumed that it is repeated every 113 times.

First, after starting, it is determined in step S21 whether or not the heater is on. If the determination result is YES, the program proceeds to step 822, and from the battery voltage vb, the comparison resistor voltage Vc, and the comparison resistor resistance value Rc, the heater resistance is calculated using the formula Rh-(Vb/Vc-1)・RC. The value Rh is determined, and then control proceeds to step S23.

In step S23, it is determined whether the internal combustion engine continues in a predetermined operating state for two seconds or more.

Here, the predetermined operating state of the internal combustion engine specifically means, for example, that the idle switch is on, the vehicle speed detected by the vehicle speed is below 5Xa+/1LX, and the internal combustion engine cooling water detected by the water temperature sensor is It is like an idling state under the condition that the temperature is 70°C or higher. When this condition is satisfied, $111 is transferred to step 82.
Proceed to step 4, and the power value ph supplied to the heater is Ph= (Vc-(Vb-Vc)/Rc/) ・(D
/256) according to the formula. Here, D is a count number corresponding to the duty ratio in the pulsed supply of power to the heater, which will be described later. Then, the newly calculated ph is further added to the memory Phn. Note that Phn is reset to zero prior to starting the illustrated tdjtl routine.

1IJtlD then proceeds to step s25. In step 825, the control passing through this step is 256
It is determined whether or not the number of times has been reached. If the answer is yes, 11m proceeds to step 826.

In step S26, the average value phm of the power 1iPh calculated 256 times is calculated by dividing the value stored in the memory Phn by 256. il, 1Jtl then proceeds to step 827.

In step S27, the calculated average power phm
From the deviation of phm from the standard value phO of the heater power corresponding to the predetermined internal combustion*i operating state, the correction iF value ΔR1 for the heater resistance value Rt is determined according to the leap number relationship as shown in FIG. 5, which is stored in the ROM. Desired. The straight solid line in the graph of FIG. 5 shows the basic change in ΔRt with respect to the deviation of phm from Pho. In this way, as phm becomes larger than Pho, ΔRt becomes a larger load value. This has the effect of lowering the target value of the heater resistance as the power supplied to the heater becomes larger than the standard value, thereby counteracting the excessive supply of power to the heater. In addition, phm
The rate of change of ΔRt relative to Pho is made relatively low only in the vicinity of Pho, as shown by the solid line, and may be corrected to become large as shown by the broken line in the figure when phm is far away from PhO. In this case, especially Phm is ph.

PhrrlPh the rate of change in the area that is too small.

It is preferable to make the rate of change even larger than the rate of change in a region where the temperature is too large, so as to prevent the heater from generating insufficient heat. IIJw then proceeds to step 328.

In step 328, the heater resistance target I currently in use is determined.
The heater resistance value is updated by adding a correction value ΔRt for the heater resistance target value Rt to Rt. TILL then proceeds to step S29.

In step 829, it is determined whether Rfi calculated each time in step 821 is equal to Rt, and if the determination result is no, the process proceeds to step S30.

In step S30, it is determined whether Rh is greater than Rt, and if the determination result is YES, the control is performed in step S30.
If the determination result is no, the process proceeds to step 332. In step S31, the value of the duty counter is reduced by 1, and in step S3
2, the duty counter 11iD is incremented by one. Here, one cycle of the duty counter is the count number corresponding to the duty ratio in the pulse-like supply of power to the heater, and the on-time of the pulse current supplied to the heater is determined by the ratio of its magnitude to 256. This is an integer value representing the duty ratio. However, this value is t+111
In order to make 11 practical, the minimum value is set not to be less than 8, and the duty ratio is 3, 12.
xm is set in the range of 5 to 100%. For this reason, processing to limit the value of D to a range of 8 to 256 is performed in steps 333 to S36 below. That is, in step 333, it is determined whether or not D exceeds 256, and if the determination result is YES, the process proceeds to step 334,
The value of D is 256. Also, in step S35, it is determined whether the value of D is 8 or less, and if it is 8 or less, the value of D is set to 8 in step 336.

υJtill then proceeds to step 337.

Note that returning to steps S21 and S29, when it is determined in step 821 that the heater is not on,
Further, when it is determined in step 329 that Rh is equal to Rt, IIJIII immediately proceeds to step S37.

In step S37, the value of the flow count C is compared with the value of the duty count D. Here, the count number called flow count C is determined every time the control bus passes through this censure routine with a cycle of 16-3. This is a variable that increases by 8 every time the value is reached, and returns to zero when the value reaches 256. Currently, this kaijin routine is said to be performed every 16m5, so
When the value of flow count C increases by 8 for each control process flow through the flow route, the value of C reaches 256 to 512 IISfFJ. This state is shown in FIG. 6(A). Further, an example of the duty count D(7) 117 is shown in FIG. 6(A).

When the temperature control of the oxygen sensor heater is performed in a predetermined normal state, the value of the duty count D determined corresponding to the phm of the power value calculated in step S26 is as shown in FIG. 6 (A> It is set to an intermediate value between 0 and 256 as shown in FIG.

As long as the value of C is determined to be smaller than D in step 338, l1jtl) proceeds to step S39, and the heater is turned on. This means that as long as the value of C is determined to be greater than or equal to a value of zero, control continues at step 840.
The heater is turned off.

This time is shown in the diagram in FIG. 6(B) in contrast to the diagram in FIG. 6<A). That is, the current supplied to the heater is a pulse type current, and the ratio of the time mb when the heater is turned on to the time a of one cycle, that is, the duty ratio of the pulse current is determined by the value of the duty count D. It has become.

When it is determined in step 341 that 70-count C has reached 256, IIJtX] is executed in step S42.
, and the value of flow count C is reset to zero.

As is clear from steps 823 to 827, the correction value for correcting the heater resistance target value for controlling the heater is calculated every 16+s when the operating state of the internal combustion engine has been in the predetermined state for more than 2 seconds. This is done by averaging 256 @ of the values calculated by selecting the time when it was maintained.
Momentary fluctuations in the operation of the internal combustion engine cause the heater temperature v.
18 is prevented. Furthermore, this 16
The value 256@, where 1S is one period, is one preferred embodiment, and the present invention is not limited thereto. The same applies to the period 512 ns of the flow count C.

FIGS. 7A and 7B each show a 70-chart of an embodiment of target resistance value abnormality detection processing. This process is a predetermined time interrupt process, and is executed, for example, at intervals of several seconds.

In step 50 of FIG. 7(A), it is determined whether the duty ratio of the energization pulse signal for the oxygen sensor heater obtained by the calculation is at the lower limit of this duty ratio, for example, 3%. If the duty ratio of the energization pulse signal is the lower limit, the lower limit counter CNT1 is incremented by [1] (step 51), and if it exceeds the lower limit, the T-limit counter C is incremented.
Decrement NT1 by "1" (step 52)
. Note that the count value of this lower limit counter C1 is a positive value.

In step 53, the count value of the lower limit counter CNTl is compared with a predetermined value CTH1 corresponding to &8 questions of about 1 minute, for example. If this count value is greater than or equal to the predetermined value Cr l-11, it is determined that the target resistance value is abnormal and step 5
Proceed to step 4. In step 54, the oxygen sensor diagnosis prohibition flag X0DNG is set to 711 in order to prohibit abnormality determination of the air-fuel ratio 11jtl based on the output value of the 1lIiA sensor 9 as described in I, and the process proceeds to step 55. In step 55, the feedback flag XFB is set to f □ V in order to prohibit the air-fuel ratio feedback tiIJIII executed based on the output value of the track sensor 9, and the process ends.

Here, the abnormality detection process of air-fuel ratio control will be explained using FIG. 9. This process is part of the main routine.

In Figure 9, the oxygen sensor diagnosis prohibition flag X0DN is shown first.
After determining whether G is vlv, flag X0DNG is vl
If abnormality detection of the air-fuel ratio 1310 is prohibited at v, this process ends.

Flag X0DNG? If QV, read the air-fuel ratio learning value KG and the air-fuel ratio feedback correction value FAF (step 81.82), calculate the product FAFXKG (step S3), and set the product FAFxKG to the predetermined values KR and KL for rich abnormality determination, respectively. Compare (step 84.85). If the product is less than a predetermined value KR, the rich abnormality flag XRICH is set to 71v as a rich abnormality (step S6), and when the product exceeds the predetermined value KL, it is considered a lean abnormality and the lean abnormality flag XREAN is set to vlv (step S7). When the product is greater than or equal to a predetermined value and less than or equal to a predetermined value KR, it is determined to be normal and abnormal flags XRIC)-1 and XREAN are set to vOv (steps 88 and 89).

In FIG. 7(A), if the count value is less than the predetermined value 0781 in step 53, the oxygen sensor diagnosis prohibition flag X0DN is set to execute abnormality determination of the oxygen sensor 9.
Step 56) to set v Ov in G, and set the feedback flag XFB to execute feedback control.
vly is set to (step 57), and the process ends.

In step 60 of FIG. 7(B), it is determined whether the duty ratio of the energization pulse signal of the oxygen sensor heater obtained by the calculation is at the upper limit of this duty ratio, for example, 100%. If the duty ratio of the energization pulse signal is at the upper limit, the upper limit counter CNT2 is incremented by [1] (step 61), and if it is less than the upper limit, the upper limit counter C is incremented by [1].
Decrement NT2 by [1] (step 62)
.

Note that the count lII of this upper limit counter C2 is a positive value.

In step 63, the count value of the upper limit counter CN T 2 is set to a predetermined value CT H2 corresponding to a time of about 1 minute, for example.
Compare with. If this count value is equal to or greater than the predetermined value 01112, it is determined that the target resistance value is abnormal, and oxygen sensor diagnosis is prohibited in order to prohibit abnormality determination of air-fuel ratio V4 control based on the output value of the oxygen sensor 9. Flag X0D
Step 64) to set Mv to NG, l elementary sensor 9
The feedback flag XFB is set to 101 in order to prohibit the air-fuel ratio feedback test based on the output value of (step 65), and the process ends.

If the count value is less than the predetermined value 0782 in step 63, the oxygen sensor diagnosis prohibition flag X0DNG is set to 107 in order to execute abnormality determination of the oxygen sensor 9 (step 66), feedback flag XFB is set in order to execute feedback t, IJIall. 717 is set (step 67), and the process ends.

FIG. 10 is a processing routine for determining the air-fuel ratio feedback correction coefficient FAF. First step 200
In this step, it is determined whether the feedback flag XFB is 717 or not. Feedback flag XFB is WQ
If the air-fuel ratio feedback Il control is prohibited at W, FΔF is set to 1.0 in step 201, and the process ends.

If the feedback flag XFB is 711 and air-fuel ratio feedback II@ is to be performed, the process advances to step 202, and the air-fuel ratio corresponding to the output voltage of the oxygen sensor is read from the RAM. Next, in step 203, this air-fuel ratio signal is compared with a reference value REF to determine whether the current air-fuel ratio is rich or lean. When the air-fuel ratio signal is larger than the reference value REF, that is, when it is rich, 10g proceeds to step 204@, and steps 204 to 20
8 processing is performed. First, in step 204, the skip flag CAF used in steps 209 to 213 is
Reset L to CAFL=O. In step 205, it is determined whether the skip flag CAFR is v Oy. When shifting from the lean side to the rich side for the first time, CARF=0, so the process advances to step 206 and the correction coefficient FAF is decreased by SKP+. Then step 2
At step 07, flag CAFR is set to vlv.

Therefore, the next time you reach step 205, step 208
, and is reduced by FAF. As shown in Figure 11, SKP+ is a much larger value than SKP+, and when it is determined that the air-fuel ratio has shifted from lean to rich, FAF
This is to perform so-called skip processing that greatly reduces the

If the air-fuel ratio signal is below the reference value REFLX, that is, if it is lean, steps 209 to 213 are performed. First, in step 209, the flag CAFR is reset to 107, and in the next step 210, it is determined whether the skip flag CAFL is 701 or not.

CAFL when moving from rich side to lean side for the first time
= 0, so proceed to step 211 and set FAF to 5KP
A skip process is performed to increase CAFL! by 2, and then in skip 212 CAFL! It is set to fi'11. After that, proceed from step 210 to step 213,
FAF is increased by one. In addition, the above-mentioned KI
and 2 are constants for integral processing to gradually decrease and increase FAF.

FIG. 12 shows a flowchart of the air-fuel ratio learning process.

In the figure, first, in step 399, it is determined whether learning conditions are satisfied. This learning condition is that the water temperature signal of the water temperature sensor 13 is 80°C or higher, the air-fuel ratio feedback 1L control is being executed, and the air-fuel ratio feedback w4t is being executed.
This means that a predetermined period of time has elapsed since the start of 1.

If the learning conditions are not satisfied, the process ends; if the learning conditions are satisfied, the process proceeds to step 400.

In step 400, the correction coefficient FAF immediately before skipping is fetched. Next, in step 401, the correction coefficient FAF fetched last time and the correction coefficient FAF fetched this time are
' The arithmetic average value FAFAV is calculated.

The calculation FAFAV=F'' is performed. In step 402, this FAFAV
It is determined whether V is 0.95 or more, and in the next step 403 it is determined whether FAFAV is 1,1 or more. Therefore, if FAFAV<0.95, proceed to step 404 and set the air-fuel ratio learning value KG to KG=KG-0.
,005. In addition, if 1, 1<FAFAV, proceed to step 405 and KG=KG+ (), O05 and t8
If 0.95≦FAFAV≦1.1, the process proceeds to step 406 where KG=KG and the process ends.

In this way, the duty ratio of the energization pulse signal of the oxygen sensor heater 24 (power supplied to the heater) exceeds the lower limit of 3% or the upper limit of 100 outside the predetermined range for a predetermined time of 1 minute e degrees or more. %, the target resistance value of the heater has changed significantly due to replacement of the oxygen sensor 9, or the learned target resistance value has been lost due to battery replacement, etc., so the sensor diagnosis prohibition flag is set. X0DN
By setting G to Mv, execution of the air-fuel ratio control abnormality detection routine as shown in FIG. 9 is prohibited, thereby preventing erroneous detection of air-fuel ratio abnormality. In addition, since the output signal of the oxygen sensor 9 is abnormal, the feedback slug
:'0' to prohibit the air-fuel ratio feedback υJial as shown in FIG. 10 using the output signal of the oxygen sensor 9, thereby preventing erroneous feedback Mil+.

Incidentally, steps 70 to 72 as shown in FIG. 8 may be provided in place of step 53 in FIG. 7(A) to provide hysteresis characteristics. In step 70, as in step 53, the count value of the lower limit counter CNT1 is set to a predetermined value CT.
If the count value CN-1 is smaller than 1-11, first, in step 71, the oxygen sensor diagnosis prohibition flag X0D is set.
Determine whether NG/It' 1 ' and set flag X0D
If NG is vlv, the count value CNT is set in step 72.
l is compared with a predetermined 11cTH1a. Predetermined value CTH1a
is a value smaller than the predetermined value Crt11, and when the count value CNTl becomes smaller than the predetermined value CTH1a and in step 71, the flag X0()NG is set to WQ? When , the process proceeds to step 56. If the count value is greater than or equal to the predetermined value CT11aLX in step 70, and if the count value CN1 is greater than the predetermined value CT)11aLX in step 72, the process proceeds to step 54. The same applies to step 63 in FIG. 7(B). can provide hysteresis characteristics.

(Effects of the Invention) As described above, the heater IJtilT of the oxygen sensor of the present invention
According to the device, replace the oxygen sensor or replace the battery! If the target resistance value is significantly different from the required value due to This is extremely useful in practice.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of the device of the present invention, Fig. 2 is a configuration diagram of an embodiment of an engine to which the device of the present invention is applied, Fig. 3 is a block diagram of an electronic TSM circuit, and Fig. 4 is a diagram of the engine control process. Flowchart of one embodiment, FIG. 5 and FIG. 6 are diagrams for explaining FIG. 4, and FIG. 7v! J is a flowchart of an embodiment of the target resistance value abnormality detection process, FIG. 8 is a 70-chart of a partial modification of the process in FIG. 7, and FIG. Example 7
0-chart, FIG. 10 is a flowchart of an embodiment of air-fuel ratio feedback tll'llJ processing, FIG. 11 is a diagram for explaining FIG. 10, and FIG. 12 is a flowchart of an embodiment of air-fuel ratio learning processing. - Chart FIG. 13 is a diagram for explaining a titania type oxygen sensor. Ml...Oxygen sensor, M2...Internal combustion 11, M3...
...Air-fuel ratio control means, M4...I control means, M5...
・Heater, M6--Target resistance value updating means, Ml...
Supply power determining means, M8...Target resistance value abnormality determining means, 1...Gasoline engine, 3...Spark plug, 8
...Air 70-meter, 10...Fuel injection valve, 13
...Knock sensor, 16...Igniter, 18...
・Rotation angle sensor V, 23...Heater resistance detector, 24・
...fli element sensor heater, 30...CPU, 50
~67...step. Figure 3 0 Figure 4 5 Figure 6 (A) Figure 7 (B) Figure 11 Figure 12 Figure 13

Claims (1)

[Scope of Claims] A control means for controlling power supplied to a heater for temperature control of an oxygen sensor that detects oxygen concentration in exhaust gas of an internal combustion engine so that the heater resistance value thereof becomes a target resistance value; and target resistance value updating means for updating the target resistance value so that the power supplied to the heater becomes a predetermined standard power in a predetermined operating state of the oxygen sensor, a target resistance value abnormality that determines that the target resistance value is abnormal when the power supplied to the heater continues to be outside the predetermined range for a predetermined period; 1. A heater control device for an oxygen sensor, comprising: determination means.