CN102495289A - Test circuit for internal resistance of oxygen sensor of automobile and method for measuring internal resistance of oxygen sensor of automobile - Google Patents

Abstract

The invention discloses a test circuit for the internal resistance of an oxygen sensor of an automobile and a method for measuring the internal resistance of the oxygen sensor of the automobile. The test circuit comprises a transistor Q1, resistors R1 to R6 and a capacitor C1, wherein an input end J1-1 of the test circuit is connected with the oxygen sensor A; the other end of the oxygen sensor A is connected with a ground wire; a base of the transistor is connected with a control end AD1 through the resistor R5, an emitter of the transistor is connected with a power supply, and a collector of the transistor is connected with the input end J1-1 through the resistor R4; one end of the resistor R6 is connected with the power supply, and the other end of the resistor R6 is connected with the base of the transistor Q1; one end of the resistor R1 is connected with the power supply, and the other end of the resistor R1 is connected with the input end J1-1; one end of the resistor R2 is connected with the input end J1-1, and the other end of the resistor R2 is connected with the ground wire; one end of the resistor R3 is connected with the input end J1-1, and the other end of the resistor R3 is connected with an output end AN1; and one end of the capacitor C1 is connected with the output end AN1, and the other end of the capacitor C1 is connected with the ground wire. The method has the advantages that: only one simple hardware circuit is required to serve as a measuring circuit, and the internal resistance of the oxygen sensor can be reliably measured, so that the aims of timely determining the ignition time of the oxygen sensor and diagnosing a fault are fulfilled.

Description

A kind of test circuit of automotive oxygen sensor internal resistance and measuring method

Technical field

The invention belongs to technical field of automotive electronics, particularly relate to a kind of test circuit and measuring method of automotive oxygen sensor internal resistance.

Background technology

Nowadays, most of automobiles have been installed three-way catalytic converter in engine exhaust system, make HC, CO, Nox in the exhaust that redox reaction take place, to reach cleaning of off-gas, to reduce the purpose of polluting.Air-fuel ratio characteristic by three-way catalytic converter can know that only near the narrow range theoretical air-fuel ratio, three-way catalytic converter could reach the highest simultaneously to the purification efficiency of HC, CO, three kinds of objectionable constituent of Nox; In case and the deviation theory value, the detergent power of three-way catalytic converter can sharply descend.

In the electronic automobile system, generally be employed in the interior lambda sensor of installing of automobile exhaust pipeline and measure the oxygen concentration in the exhaust, for control device provides feedback signal, converge on theoretical value with the control air-fuel ratio, as shown in Figure 1.In a single day lambda sensor breaks down, and the computer that makes electronic fuel injection system can not be obtained the information of oxygen concentration in the gas outlet, thereby can not carry out FEEDBACK CONTROL to air-fuel ratio, thereby engine consumption and exhaust pollution are increased.

Through measuring the lambda sensor internal resistance, can confirm that it is its light-off time that lambda sensor is started working.The lambda sensor internal resistance that measures also is used for the lambda sensor fault diagnosis; But do not see the concrete grammar of lambda sensor essential resistance on-line measurement at present as yet.

Summary of the invention

In order to address the above problem, the object of the present invention is to provide a kind of test circuit and measuring method of automotive oxygen sensor internal resistance.

In order to achieve the above object, the test circuit of automotive oxygen sensor internal resistance provided by the invention comprises: transistor Q1, resistor R 1-R6 and capacitor C1; Wherein: the input end J1-1 of circuit is connected with lambda sensor A, and Ri is the equivalent internal resistance of lambda sensor, and the other end of lambda sensor A is connected with ground wire; AD1 is a control end, and the output terminal of automobile ECU is realized the break-make control to transistor Q1 through control end AD1; AN1 is the output terminal of circuit, is used to export oxygen sensor voltage signal u; Transistor Q1 is the positive-negative-positive switching tube, and its base stage is connected with control end AD1 through resistance R 5, and emitter is connected with power supply VCC, and collector is connected with input end J1-1 through resistance R 4; One end of resistor R 6 is connected with power supply VCC, and the other end is connected with the base stage of transistor Q1; One end of resistor R 1 is connected with power supply VCC, and the other end is connected with input end J1-1; One end of resistor R 2 is connected with input end J1-1, and the other end is connected with ground wire; One end of resistor R 3 is connected with input end J1-1, and the other end is connected with output terminals A N1; The end of capacitor C1 is connected with output terminals A N1, and the other end is connected with ground wire.

The measuring method of automotive oxygen sensor internal resistance provided by the invention comprises the following steps of carrying out in order:

Step 1, internal resistance measurement enable condition judgment: necessary condition and adequate condition according to the internal resistance test enable are judged, if condition satisfies then gets into next step, otherwise continue to wait for;

Step 2, internal resistance measurement:, try to achieve the measured value of lambda sensor internal resistance then through calculating through the output signal of collecting test circuit under different conditions;

Step 3, internal resistance measurement value rationality are judged: according to the data of having grasped, judge R _MESRationality;

In step 1, the described condition of enabling comprises necessary condition and adequate condition:

1) necessary condition

A) engine is not in towing astern oil-break operating mode

B) engine load is not excessive

C) lambda sensor non-fault

D) the oxygen sensor voltage signal is reasonable

2) adequate condition

Be divided into two kinds of situation and handle according to whether the oxygen sensor voltage moving average is limited; When lambda sensor output signal amplitude amplitude of variation is very little or overall dense partially or overall rare partially; Think that lambda sensor is tending towards aging, this moment, oxygen sensor signal was in restricted mode; Otherwise think that lambda sensor is in non-restricted mode;

A) when oxygen sensor signal is in restricted mode, carry out deciding the internal resistance measurement of frequency;

B) when oxygen sensor signal is in non-restricted mode, need to satisfy: oxygen sensor signal is in rarer state and oxygen sensor signal changes milder.

In step 2, described internal resistance measurement comprises the following steps of carrying out in order:

1) measures oxygen sensor voltage signal u ₁: before internal resistance measurement enables, gather the oxygen sensor voltage signal u under the Q1 off-state, u is arranged this moment ₁=u shields the oxygen sensor voltage signal simultaneously;

2) measure oxygen sensor voltage signal u ₂: the time-delay of closed Q1 and process certain hour, after the transient process of waiting signal finishes, gather the oxygen sensor voltage signal u of this moment, u is arranged this moment ₂=u breaks off Q1 then;

3) wait for that transient process finishes: in official hour, the variation of monitoring oxygen sensor voltage signal u is if u＞u occurs in official hour ₂, then cancel shielding at once to the oxygen sensor voltage signal; If u≤u is arranged all the time at official hour ₂, the moment that then arrives is at the appointed time cancelled shielding;

4) calculate internal resistance measurement value R _MES: obtaining u ₁, u ₂After, utilize by the pairing circuit equation group derivation of the on off operating mode lambda sensor internal resistance computing formula that draws, obtain the measured value of current lambda sensor internal resistance, the result of calculation suspense is internal resistance measurement value R _MES

In step 3, the concrete steps that described rationality is judged are following:

1) according to measured value R _MESTable look-up the corresponding T of this value _{C_MES}

2) select measured value R _MESScope, measured value R _MESBound be respectively R _TOLAnd R _BOL

3) table look-up and draw R _TOLAnd R _BOLCorresponding ceramic temperature bound T _{C_TOL}And T _{C_BOL}

4) according to current T _{C_TOL}And T _{C_BOL}Ask the moving average T of ceramic temperature bound _{C_TOL_MMV}And T _{C_BOL_MMV}

5) with T _{C_MES}With T _{C_TOL_MMV}And T _{C_BOL_MMV}Relatively, if T _{C_BOL_MMV}＜T _{C_MES}＜T _{C_TOL_MMV}, think that then the internal resistance measurement value is reasonably, makes R _i=R _MESOtherwise be irrational, R _iKeep initial value.

Step 2 4) calculate internal resistance measurement value R _MESIn the substep, described lambda sensor internal resistance calculating formula process is following:

When Q1 broke off, the note oxygen sensor voltage was u ₁, because the R3 no current passes through, can obtain:

$\frac{V_{\mathrm{cc}}-u_1}{R_1}=\frac{u_1}{R_i}+\frac{u_1}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA0000117359160000021.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}$

When Q1 was closed, the note oxygen sensor voltage was u ₂, because the R3 no current passes through, can obtain:

$\frac{V_{\mathrm{cc}}-u_2}{\frac{R_1\&CenterDot;R_4}{R_1+R_4}}=\frac{u_2}{R_i}+\frac{u_2}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA0000117359160000021.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}$

Consider R ₂＜＜R ₁, therefore can obtain:

$R_i=\frac{R_4(u_2-u_1)}{V_{\mathrm{Cc}}-(u_2-u_1)\frac{R_4}{R_2}-u_2}$ (formula 1)

Formula 1 is lambda sensor internal resistance computing formula, will measure resulting u ₁, u ₂After being updated in the formula 1, can try to achieve the measured value R of lambda sensor internal resistance Ri _MES

Step 3 4) substep in, the moving average T of described ceramic temperature bound _{C_TOL_MMV}And T _{C_BOL_MMV}Computing formula be:

T _{c_TOL_MMV}(n)＝T _{c_TOL_MMV}(n-1)+C _filter·[T _{c_TOL}-T _{c_TOL_MMV}(n-1)]

T _{c_BOL_MMV}(n)＝T _{c_BOL_MMV}(n-1)+C _filter·[T _{c_BOL}-T _{c_BOL_MMV}(n-1)]

Wherein: C _FilterIt is the filter factor that to demarcate.

The measuring method of automotive oxygen sensor internal resistance provided by the invention only needs a very simple hardware circuit as metering circuit, has realized the internal resistance of reliable measuring lambda sensor, thereby has reached the purpose of in time confirming lambda sensor light-off time and fault diagnosis.

Description of drawings

Fig. 1 is an Automotive Air Fuel Ratio control principle synoptic diagram.

Fig. 2 is the test circuit schematic diagram of automotive oxygen sensor internal resistance provided by the invention.

Fig. 3 is the measuring method process flow diagram of automotive oxygen sensor internal resistance provided by the invention.

Embodiment

Be elaborated below in conjunction with accompanying drawing and specific embodiment test circuit and measuring method to automotive oxygen sensor internal resistance provided by the invention.

The measuring method that the purpose of this invention is to provide a kind of automotive oxygen sensor internal resistance; The present invention only need use a simple test circuit; Change the parameter of circuit through the break-make of on-off element; And gather the output voltage of lambda sensor under the on off operating mode successively, can realize measurement through calculating then to the lambda sensor internal resistance.

Fig. 1 illustrates Automotive Air Fuel Ratio control principle synoptic diagram, and Fig. 2 shows the test circuit schematic diagram of automotive oxygen sensor internal resistance provided by the invention; Like Fig. 1, shown in Figure 2, described test circuit comprises: transistor Q1, resistor R 1-R6 and capacitor C1; Wherein: the input end J1-1 of circuit is connected with lambda sensor A, and Ri is the equivalent internal resistance of lambda sensor, and the other end of lambda sensor A is connected with ground wire; AD1 is a control end, and the output terminal of automobile ECU (electronic control unit) is realized the break-make control to transistor Q1 through control end AD1; AN1 is the output terminal of circuit, is used to export oxygen sensor voltage signal u; Transistor Q1 is the positive-negative-positive switching tube, and its base stage is connected with control end AD1 through resistance R 5, and emitter is connected with power supply VCC, and collector is connected with input end J1-1 through resistance R 4; One end of resistor R 6 is connected with power supply VCC, and the other end is connected with the base stage of transistor Q1; One end of resistor R 1 is connected with power supply VCC, and the other end is connected with input end J1-1; One end of resistor R 2 is connected with input end J1-1, and the other end is connected with ground wire; One end of resistor R 3 is connected with input end J1-1, and the other end is connected with output terminals A N1; The end of capacitor C1 is connected with output terminals A N1, and the other end is connected with ground wire.

Fig. 3 shows the operational flowchart of the measuring method of automotive oxygen sensor internal resistance provided by the invention; As shown in Figure 3, the measuring method of automotive oxygen sensor internal resistance provided by the invention comprises the following steps of carrying out in order:

Step 1, internal resistance measurement enable condition judgment: necessary condition and adequate condition according to the internal resistance test enable are judged, if condition satisfies then gets into next step, otherwise continue to wait for; The condition of enabling comprises necessary condition and adequate condition:

1, necessary condition

A) engine is not in towing astern oil-break operating mode

B) engine load is not excessive

C) lambda sensor non-fault

D) the oxygen sensor voltage signal is reasonable

2, adequate condition

Be divided into two kinds of situation and handle according to whether the oxygen sensor voltage moving average is limited.When lambda sensor output signal amplitude amplitude of variation is very little or overall dense partially or overall rare partially, think that lambda sensor is tending towards aging, this moment, oxygen sensor signal was in restricted mode; Otherwise think that lambda sensor is in non-restricted mode.

A) when oxygen sensor signal is in restricted mode, carry out deciding the internal resistance measurement of frequency, that is: be at interval with the regular hour, enable internal resistance measurement continuously, until obtaining rational internal resistance value R _iTill.

B) when oxygen sensor signal is in non-restricted mode, need the condition of enabling of satisfied internal resistance measurement to be: oxygen sensor signal is in rarer state and oxygen sensor signal changes milder.Step 2, internal resistance measurement:, try to achieve the measured value of lambda sensor internal resistance then through calculating through the output signal of collecting test circuit under different conditions;

Measuring principle: as shown in Figure 2; The ultimate principle of lambda sensor internal resistance measurement is a make and break process through on-off element Q1 in the test circuit; Change the type of attachment of circuit, measure the output voltage u of lambda sensor under the break-make two states this moment respectively, list the circuit equation group and the calculating of corresponding two states according to circuit parameter and find the solution; Draw the computing formula of lambda sensor internal resistance, utilize formula to draw lambda sensor internal resistance value Ri;

The initial state of measuring: before internal resistance measurement enabled, transistor Q1 broke off, and the oxygen sensor voltage signal u that test circuit is gathered need send auxiliary fuel supply-system to, as the feedback signal of its closed-loop control;

Measuring process: described internal resistance measurement comprises the following steps of carrying out in order:

1) measures oxygen sensor voltage signal u ₁: before internal resistance measurement enables, gather the oxygen sensor voltage signal u under the Q1 off-state, u is arranged this moment ₁=u shields the oxygen sensor voltage signal simultaneously.Here said shielding is meant no longer the foundation of real oxygen sensor voltage signal as the air-fuel ratio closed-loop control;

2) measure oxygen sensor voltage signal u ₂: the time-delay of closed Q1 and process certain hour, after the transient process of waiting signal finishes, gather the oxygen sensor voltage signal u of this moment, u is arranged this moment ₂=u breaks off Q1 then;

3) wait for that transient process finishes: in official hour, the variation of monitoring oxygen sensor voltage signal u is if u＞u occurs in official hour ₂, then cancel shielding at once to the oxygen sensor voltage signal; If u≤u is arranged all the time at official hour ₂, the moment that then arrives is at the appointed time cancelled shielding, and the purpose that shielding is cancelled in time-delay also is that the waiting signal transient process finishes.

4) calculate internal resistance measurement value R _MES: obtaining u ₁, u ₂After, utilize by the pairing circuit equation group derivation of the on off operating mode lambda sensor internal resistance computing formula that draws, obtain the measured value of current lambda sensor internal resistance, the result of calculation suspense is internal resistance measurement value R _MES

Step 3, internal resistance measurement value rationality are judged: according to the data of having grasped, judge R _MESRationality;

The judgement of internal resistance measurement value rationality has utilized lambda sensor internal resistance R _iTemperature T ceramic with it _cMapping relations.Usually, lambda sensor has negative temperature coefficient, R _iWith T _cRising and reduce, both sides relation is exactly an one dimension calibration scale in practical application.

The concrete steps that rationality is judged are following:

1) according to measured value R _MESTable look-up the corresponding T of this value _{C_MES}

2) select measured value R _MESScope, measured value R _MESBound be respectively R _TOLAnd R _BOL

3) table look-up and draw R _TOLAnd R _BOLCorresponding ceramic temperature bound T _{C_TOL}And T _{C_BOL}

4) according to current T _{C_TOL}And T _{C_BOL}Ask the moving average T of ceramic temperature bound _{C_TOL_MMV}And T _{C_BOL_MMV}

5) with T _{C_MES}With T _{C_TOL_MMV}And T _{C_BOL_MMV}Relatively, if T _{C_BOL_MMV}＜T _{C_MES}＜T _{C_TOL_MMV}, think that then the internal resistance measurement value is reasonably, makes R _i=R _MESOtherwise be irrational, R _iKeep initial value.

Step 2 4) calculate internal resistance measurement value R _MESIn the substep, described lambda sensor internal resistance calculating formula process is following:

As shown in Figure 2, when Q1 broke off, the note oxygen sensor voltage was u ₁, because the R3 no current passes through, can obtain:

$\frac{V_{\mathrm{cc}}-u_1}{R_1}=\frac{u_1}{R_i}+\frac{u_1}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA0000117359160000021.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}$

When Q1 was closed, the note oxygen sensor voltage was u ₂, because the R3 no current passes through, can obtain:

$\frac{V_{\mathrm{cc}}-u_2}{\frac{R_1\&CenterDot;R_4}{R_1+R_4}}=\frac{u_2}{R_i}+\frac{u_2}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA0000117359160000021.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}$

Consider R ₂＜＜R ₁, therefore can obtain:

$R_i=\frac{R_4(u_2-u_1)}{V_{\mathrm{Cc}}-(u_2-u_1)\frac{R_4}{R_2}-u_2}$ (formula 1)

Formula 1 is lambda sensor internal resistance computing formula, will measure resulting u ₁, u ₂After being updated in the formula 1, can try to achieve the measured value R of lambda sensor internal resistance Ri _MES

Step 3 4) substep in, the moving average T of described ceramic temperature bound _{C_TOL_MMV}And T _{C_BOL_MMV}Computing formula be:

T _{c_TOL_MMV}(n)＝T _{c_TOL_MMV}(n-1)+C _filter·[T _{c_TOL}-T _{c_TOL_MMV}(n-1)]

T _{c_BOL_MMV}(n)＝T _{c_BOL_MMV}(n-1)+C _filter·[T _{c_BOL}-T _{c_BOL_MMV}(n-1)]

Wherein: C _FilterIt is the filter factor that to demarcate.

Claims (7)

1. the test circuit of an automotive oxygen sensor internal resistance, it is characterized in that: the test circuit of described automotive oxygen sensor internal resistance comprises: transistor Q1, resistor R 1-R6 and capacitor C1; Wherein: the input end J1-1 of circuit is connected with lambda sensor A, and Ri is the equivalent internal resistance of lambda sensor, and the other end of lambda sensor A is connected with ground wire; AD1 is a control end, and the output terminal of automobile ECU is realized the break-make control to transistor Q1 through control end AD1; AN1 is the output terminal of circuit, is used to export oxygen sensor voltage signal u; Transistor Q1 is the positive-negative-positive switching tube, and its base stage is connected with control end AD1 through resistance R 5, and emitter is connected with power supply VCC, and collector is connected with input end J1-1 through resistance R 4; One end of resistor R 6 is connected with power supply VCC, and the other end is connected with the base stage of transistor Q1; One end of resistor R 1 is connected with power supply VCC, and the other end is connected with input end J1-1; One end of resistor R 2 is connected with input end J1-1, and the other end is connected with ground wire; One end of resistor R 3 is connected with input end J1-1, and the other end is connected with output terminals A N1; The end of capacitor C1 is connected with output terminals A N1, and the other end is connected with ground wire.

2. measuring method that adopts the test circuit of the described automotive oxygen sensor internal resistance of claim 1, it is characterized in that: described measuring method comprises the following steps of carrying out in order:

Step 1, internal resistance measurement enable condition judgment: necessary condition and adequate condition according to the internal resistance test enable are judged, if condition satisfies then gets into next step, otherwise continue to wait for;

Step 2, internal resistance measurement:, try to achieve the measured value of lambda sensor internal resistance then through calculating through the output signal of collecting test circuit under different conditions;

Step 3, internal resistance measurement value rationality are judged: according to the data of having grasped, judge R _MESRationality;

3. the measuring method of automotive oxygen sensor internal resistance according to claim 2 is characterized in that: in step 1, the described condition of enabling comprises necessary condition and adequate condition:

1) necessary condition

A) engine is not in towing astern oil-break operating mode

B) engine load is not excessive

C) lambda sensor non-fault

D) the oxygen sensor voltage signal is reasonable

2) adequate condition

Be divided into two kinds of situation and handle according to whether the oxygen sensor voltage moving average is limited; When lambda sensor output signal amplitude amplitude of variation is very little or overall dense partially or overall rare partially; Think that lambda sensor is tending towards aging, this moment, oxygen sensor signal was in restricted mode; Otherwise think that lambda sensor is in non-restricted mode;

A) when oxygen sensor signal is in restricted mode, carry out deciding the internal resistance measurement of frequency;

B) when oxygen sensor signal is in non-restricted mode, need to satisfy: oxygen sensor signal is in rarer state and oxygen sensor signal changes milder.

4. the measuring method of automotive oxygen sensor internal resistance according to claim 2 is characterized in that: in step 2, described internal resistance measurement comprises the following steps of carrying out in order:

1) measures oxygen sensor voltage signal u ₁: before internal resistance measurement enables, gather the oxygen sensor voltage signal u under the Q1 off-state, u is arranged this moment ₁=u shields the oxygen sensor voltage signal simultaneously;

2) measure oxygen sensor voltage signal u ₂: the time-delay of closed Q1 and process certain hour, after the transient process of waiting signal finishes, gather the oxygen sensor voltage signal u of this moment, u is arranged this moment ₂=u breaks off Q1 then;

3) wait for that transient process finishes: in official hour, the variation of monitoring oxygen sensor voltage signal u is if u＞u occurs in official hour ₂, then cancel shielding at once to the oxygen sensor voltage signal; If u≤u is arranged all the time at official hour ₂, the moment that then arrives is at the appointed time cancelled shielding;

4) calculate internal resistance measurement value R _MES: obtaining u ₁, u ₂After, utilize by the pairing circuit equation group derivation of the on off operating mode lambda sensor internal resistance computing formula that draws, obtain the measured value of current lambda sensor internal resistance, the result of calculation suspense is internal resistance measurement value R _MES

5. the measuring method of automotive oxygen sensor internal resistance according to claim 2 is characterized in that: in step 3, the concrete steps that described rationality is judged are following:

1) according to measured value R _MESTable look-up the corresponding T of this value _{C_MES}

2) select measured value R _MESScope, measured value R _MESBound be respectively R _TOLAnd R _BOL

3) table look-up and draw R _TOLAnd R _BOLCorresponding ceramic temperature bound T _{C_TOL}And T _{C_BOL}

4) according to current T _{C_TOL}And T _{C_BOL}Ask the moving average T of ceramic temperature bound _{C_TOL_MMV}And T _{C_BOL_MMV}

5) with T _{C_MES}With T _{C_TOL_MMV}And T _{C_BOL_MMV}Relatively, if T _{C_BOL_MMV}＜T _{C_MES}＜T _{C_TOL_MMV}, think that then the internal resistance measurement value is reasonably, makes R _i=R _MESOtherwise be irrational, R _iKeep initial value.

6. the measuring method of automotive oxygen sensor internal resistance according to claim 4 is characterized in that: step 2 4) calculate internal resistance measurement value R _MESIn the substep, described lambda sensor internal resistance calculating formula process is following:

When Q1 broke off, the note oxygen sensor voltage was u ₁, because the R3 no current passes through, can obtain:

$\frac{V_{\mathrm{cc}}-u_1}{R_1}=\frac{u_1}{R_i}+\frac{u_1}{R_2}$

When Q1 was closed, the note oxygen sensor voltage was u ₂, because the R3 no current passes through, can obtain:

$\frac{V_{\mathrm{cc}}-u_2}{\frac{R_1\&CenterDot;R_4}{R_1+R_4}}=\frac{u_2}{R_i}+\frac{u_2}{R_2}$

Consider R ₂＜＜R ₁, therefore can obtain:

$R_i=\frac{R_4(u_2-u_1)}{V_{\mathrm{Cc}}-(u_2-u_1)\frac{R_4}{R_2}-u_2}$ (formula 1)

Formula 1 is lambda sensor internal resistance computing formula, will measure resulting u ₁, u ₂After being updated in the formula 1, can try to achieve the measured value R of lambda sensor internal resistance Ri _MES

7. the measuring method of automotive oxygen sensor internal resistance according to claim 5 is characterized in that: step 3 4) substep in, the moving average T of described ceramic temperature bound _{C_TOL_MMV}And T _{C_BOL_MMV}Computing formula be:

T _{c_TOL_MMV}(n)＝T _{c_TOL_MMV}(n-1)+C _filter·[T _{c_TOL}-T _{c_TOL_MMV}(n-1)]

T _{c_BOL_MMV}(n)＝T _{c_BOL_MMV}(n-1)+C _filter·[T _{c_BOL}-T _{c_BOL_MMV}(n-1)]

Wherein: C _FilterIt is the filter factor that to demarcate.

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