KR0158718B1 - Trouble detecting system for engine - Google Patents

Abstract

Improve the accuracy of diagnosis of the fuel supply system. Air-fuel ratio learning correction value based on the air-fuel ratio feedback correction amount while performing air-fuel ratio feedback control based on the signals of the O ₂ sensor 12 and the O ₂ sensor 12 which are opened in the exhaust passage upstream from the catalyst and output according to the air-fuel ratio of the exhaust. Means 101 for updating the engine, means 102 for determining that the fuel supply system is abnormal when the air-fuel ratio learning correction value deviates from the reference value by a predetermined ratio or more, means 103 for detecting the fuel concentration in the engine oil and detected fuel Diagnostic stop means 104 for stopping abnormality determination of the fuel system when the concentration is larger than the reference value is provided.

Description

Self diagnosis device of engine

1 is a claim correspondence of the present invention.

2 is a system diagram of an engine showing the same embodiment.

3 is a flowchart showing an example of the same air-fuel ratio control.

4 is a flowchart for explaining the same failure diagnosis.

5 is a flowchart for explaining a fault diagnosis according to another embodiment.

6 is a flow chart for estimating fuel concentration to engine oil in another embodiment.

FIG. 7 is a characteristic diagram showing the relationship between the fuel concentration addition value B and the coolant temperature at low temperature start-up.

8 is a characteristic diagram showing the relationship between the fuel concentration addition value C and the fuel increase rate at the time of fuel increase.

* Explanation of symbols for main parts of the drawings

12: O ₂ sensor 101: air fuel ratio learning correction value updating means

102: abnormality diagnosis means 103: fuel concentration detection means in the engine oil

104: diagnostic stop means

[Industrial use]

The present invention relates to an apparatus for self-diagnosis of a failure of an electronically controlled fuel injection engine.

[Prior art]

In other words, in order to increase the conversion efficiency of CO, HC, and NOx in exhaust gas in the three-way catalyst system, feedback control of the air-fuel ratio is performed so that the air-fuel ratio in the exhaust gas passing through the catalyst is settled in a narrow range centered on the theoretical air-fuel ratio.

The engine in which the feedback control of the air-fuel ratio is performed is made to approximate the base air-fuel ratio to the theoretical air-fuel ratio by learning in order to reduce the deviation of the air-fuel ratio resulting from the difference of the base air-fuel ratio at the time of transition.

However, in the case of such an air-fuel ratio control device, the air-fuel ratio may be disturbed so as to cause a problem in engine characteristics due to a failure of the actuator or sensor of the fuel supply system or deterioration with time, so that a request to confirm the diagnosis more than that is required. have.

For this reason, it is proposed to diagnose that a failure has occurred in the fuel supply system when the learning correction value of the air-fuel ratio is greatly shifted, as shown in Japanese Patent Application Laid-Open No. 2-28700, for example.

[Problems that the invention tries to solve]

However, in an engine in which a bleed-by gas that has passed through a gap between a piston ring and a combustion chamber is refluxed into an intake passage and reburned, the fuel ratio contained in the bleed-by gas is updated when the air-fuel ratio learning correction value is updated during the return of the bleed-by gas. The bass air-fuel ratio is greatly disturbed by this.

However, in the configuration of diagnosing a failure from the signal of the O ₂ sensor as in the conventional apparatus, the signal of the O ₂ sensor becomes rich during operation where the browby gas is returned in addition to the failure of the actuator or the sensor of the fuel supply system. Since there is a possibility that the case is determined to be abnormal, there is a problem that the accuracy of fault diagnosis is insufficient.

An object of the present invention is to focus on the above-mentioned problems and to improve the accuracy of failure diagnosis of a fuel supply system.

[Means for solving the problem]

The present invention is based on the air-fuel ratio feedback correction amount while performing the air-fuel ratio feedback control based on the signals of the O ₂ sensor 12 and the O ₂ sensor 12 which are opened in the exhaust passage upstream from the catalyst and output by the air-fuel ratio of the exhaust gas. Means 101 for updating the air-fuel ratio learning correction value, means 102 for determining that the fuel supply system is abnormal when the air-fuel ratio learning correction value deviates by a predetermined ratio or more from the reference value, and means for detecting the fuel concentration in the engine oil ( 103 and diagnostic stop means 104 for stopping the determination of an abnormality in the fuel supply system when the detected fuel concentration is larger than the reference value.

[Action]

When the output of the O ₂ sensor 12 greatly changes to the rich side or the lean side due to the detection of the fuel supply amount or the failure of the control system, the determining means 102 determines the fuel supply amount based on the air-fuel ratio learning correction value. The detection or control system determines that there is an error.

The diagnostic stop means 104 stops the abnormality determination of the fuel supply system when the fuel concentration in the engine oil is larger than the reference value, so that the output of the O ₂ sensor 12 is rich by the fuel flowing into the intake passage by the browby gas. Can be avoided by mistake in the fuel supply system.

EXAMPLE

Next, embodiments of the present invention will be described with reference to the drawings.

In FIG. 2, reference numeral 1 denotes an engine body, 3 an intake passage, and 5 an exhaust passage. A three-way catalyst 6 is provided in the exhaust passage 5 to oxidize CO and HC in the exhaust and to reduce NOx.

(4) is a fuel injection valve for injecting fuel into the intake passage (3), and (30) is before ignition to ignite the mixer of the combustion chamber (32).

In addition, a browby gas passage and an engine (not shown) for guiding the browby gas that has passed through the gap of the piston ring 33 in the combustion chamber 32 of the engine 1 and exits the crank chamber 34 to the intake passage 3 are provided. A flow control valve for regulating the reflux amount of the browby gas in response to the operating state is provided to reburn the browby gas.

The control unit 20 is provided to control the injection amount of the fuel injection valve 4 and to control the ignition timing by the pre-ignition 30 at the same time.

The control unit 20 is composed of a microcomputer consisting of a CPU 21, a ROM 22, a RAM 23, an I / O port 24, and the like. Intake air quantity signal Qa, engine speed signal N from crank angle sensor 10, opening degree signal TVO of throttle valve 8 from throttle sensor 9, water temperature signal Tw from water temperature sensor 11, exhaust passage In order to obtain this fuel injection amount by inputting the oxygen concentration signal Vs in the exhaust gas from the O ₂ sensor 12 retrofitted in (5) and the like according to these operating conditions, the driving pulse signal Si is converted into the fuel injection balance ( 4) are sent to.

The control unit 20 feedback-corrects the fuel injection amount from the fuel injection valve 4 so as to maintain the air-fuel ratio average value near the theoretical air-fuel ratio based on the output signal Vs from the O ₂ sensor 12, Make sure that you have enough skills. The fuel injection amount Ti is calculated by the following equation.

Ti = Tp × COEF × α × α ₀ + Ts

Here, Tp is Tp = K × Qa / N when K is an integer in the basic fuel injection amount. α is a feedback coefficient of the air-fuel ratio, and α ₀ is a learning correction coefficient corresponding to the engine operating conditions determined by the rotation speed and the load. Ts is the voltage correction quotient based on battery voltage.

For feedback control of the air-fuel ratio, based on the output signal of the O ₂ sensor 12, it is determined from the slice level corresponding to the theoretical air-fuel ratio whether the current air-fuel ratio is the rich side or the lean side, as shown in FIG. the output of the O ₂ sensor 12, the stoichiometric (theoretical air-fuel ratio), the slice is higher than the level of the air-fuel ratio of the equivalent has side rich in this case lowers by a first reference value for the air-fuel ratio feedback correction coefficient α to P _R share slowly constant gradient there I _R as The air-fuel ratio is moved to the lean side when the output of the O ₂ sensor 12 is lower than the slice level equivalent to the lean.In this case, the air-fuel ratio feedback correction coefficient α is initially lowered by the reference value P _L. From there, it is controlled to make the air-fuel ratio lighter by gradually lowering it to a constant slope I _L. By repeating this control, the actual air-fuel ratio is gradually brought closer to the stoke.

However, if the base air-fuel ratio is shifted from the stoke, it takes time until the difference in the base air-fuel ratio is returned to the stoke by the feedback control when the driving area is greatly changed. From there, the base air-fuel ratio is brought close to the Stokes to eliminate the deviation of the air-fuel ratio caused by the difference in the base air-fuel ratio in the event of transient learning and to improve the feedback controllability.

The learning correction coefficient α ₀ is obtained in the following order.

(1) In the steady state, the engine operating condition at that time and the control center value αC of α are detected.

(2) The α ₀ that has been learned so far is searched corresponding to the engine operating condition.

(3) The value of α ₀ + Δα / M is obtained from αC and α ₀ , and the memory is updated with the result (learning correction value) as new α ₀ .

Also, Δα represents the amount of deviation from the reference value, and Δα = αC ₁ α - α ₁ and α ₁ is the reference value, for example, be 1. M is an integer.

As a means 103 for detecting the fuel concentration in the engine oil shown in FIG. 1, a fuel concentration sensor 13 for outputting a signal corresponding to the fuel (gasoline) concentration of the engine oil is provided.

The fuel concentration sensor 13 is a well-known HC gas sensor for measuring the concentration of HC gas in the atmosphere and is installed in a browby gas passage near an inlet for introducing browby gas into the intake passage and detected as the concentration of gasoline increases. It is to detect the gasoline concentration in engine oil by using the phenomenon that HC concentration becomes high.

As described above, the control unit 20 performs feedback control of the air-fuel ratio of the engine 1 and at the same time, except for the O ₂ sensor 12 and the fuel concentration detecting means 103 in the engine oil shown in FIG. 101, 102, and 103, and have a function of diagnosing the abnormality of the fuel supply system based on a detection signal from the O ₂ sensor 12 under the condition that the fuel concentration of the engine oil is equal to or less than a predetermined value. have. 14 is a warning light to warn of this when diagnosed as abnormal.

FIG. 4 is a flowchart for diagnosing abnormalities and is executed at regular intervals under the operating conditions in which the learning condition of air-fuel ratio is established.

In this regard, first, the detection value of the fuel concentration in the engine oil is read from the fuel concentration sensor 13, and it is determined whether the detected fuel concentration is smaller than the reference value (steps 41 and 42).

The update of the air-fuel ratio learning correction value is stopped when the fuel concentration is larger than the reference value, and the air-fuel ratio learning correction value is updated when the fuel concentration is lower than the reference value (step 43).

Subsequently, the deviation A of the air-fuel ratio learning correction value is calculated based on the operating condition that the diagnosis permitting condition is satisfied, and it is determined whether the calculation result A is larger than the judgment value, and when the amount A of the air-fuel ratio learning correction value A is less than the judgment value, the fuel supply system If it is determined that it is normal and the deviation A of the air-fuel ratio learning correction value is larger than the determination value, it is determined that the fuel supply system is abnormal, and the warning lamp 14 is operated (steps 44 to 48).

As described above, when the air-fuel ratio becomes rich due to the fuel flowing into the intake passage 3 by the browby gas, the air-fuel ratio learning can be avoided by erroneously learning the air-fuel ratio by stopping the updating of the air-fuel ratio learning correction value. It is possible to avoid the determination of a mistake and to diagnose a high accuracy fault.

FIG. 5 is a flow chart for diagnosing an abnormality in another embodiment and is executed at regular intervals as an operating condition in which a learning condition of an air-fuel ratio is established.

When this is explained, first, the air-fuel ratio learning correction value is updated and the detected value of the fuel concentration in the engine oil is input from the fuel concentration sensor 13 to determine whether the detected fuel concentration is less than the reference value (steps 43, 41, 42).

When the fuel concentration is less than the reference value, the timer T waits for the predetermined time to elapse (steps 51 and 52), and it is determined whether the fuel supply system is abnormal at the shifted amount A of the air-fuel ratio learning correction value (steps 44 to 48). In the case where the fuel concentration is larger than the reference value, the update of the air-fuel ratio learning correction value is stopped and the timer T is cleared (step 53).

As described above, even when the fuel concentration in the engine oil is large, the air-fuel ratio learning correction value can be updated to increase the frequency of updating the air-fuel ratio learning correction value.

Even if the fuel concentration in the engine oil decreases, the fuel flowing into the intake passage 3 by the browby gas is sufficiently reduced after a predetermined time T, and the abnormality of the fuel supply system can be diagnosed, thereby making it possible to diagnose the abnormality with high accuracy. have.

FIG. 6 is a flowchart for estimating the fuel concentration in engine oil in the operating state of the engine as the fuel concentration detecting means 103 in the browby gas shown in FIG.

In other words, when the start switch is turned ON, the fuel concentration addition B in the engine oil is searched based on the coolant temperature in the table shown in FIG. Calculated as + B (steps 61 to 63).

When the fuel increase rate is larger than the predetermined value and the engine load is larger than the predetermined value, the fuel concentration addition value C in the engine oil is retrieved from the table shown in FIG. 8 based on the fuel increase rate from the table shown in FIG. The fuel concentration estimate A in the oil is calculated as A = A + C (steps 64 to 67).

Operation with coolant temperature between the lower limit N ₁ and the upper limit N ₂ and the fuel injection amount between the lower limit P ₁ and the upper limit P ₂ at coolant temperature below the upper limit T ₁ to determine the operating state in which the fuel concentration in the engine oil is reduced. The state is determined (steps 68 to 72).

The fuel concentration estimation value A is calculated as A = A-D using the predetermined subtraction value D in the operating state in which the fuel concentration in the engine oil is reduced (step 73).

In this way, by calculating the fuel concentration A in the engine oil in accordance with the engine operating state, the sensor 13 for detecting the fuel concentration in the embodiment shown in FIG. 2 can be closed. The fuel concentration estimate A in this engine oil is also stored in the engine stop attempt and reflected in the next operation.

[Effects of the Invention]

As described above, the present invention stops the determination of an abnormality in the fuel supply system based on the detection value of the O ₂ sensor when the fuel concentration in the engine oil is larger than the reference value. This makes it possible to avoid judging the case where the output of the O ₂ sensor becomes rich due to a failure of the fuel supply system.

Claims (3)

Learn to open from the catalyst in the upstream exhaust passage and updates the air-fuel ratio learning correction value on the basis of the air-fuel ratio feedback correction amount as the basis of the signal from the O ₂ sensor and, O ₂ sensor for performing the output corresponding to the exhaust air line of the air-fuel ratio feedback control correction value A self-diagnostic apparatus for an engine having an update means and determination means for determining that there is an abnormality in the fuel supply system when the air-fuel ratio learning correction value is shifted from the reference value by a predetermined ratio or more, the fuel for detecting the fuel concentration in the engine oil A self-diagnosis apparatus for an engine provided with a concentration detecting means and a diagnostic stop means for stopping an abnormality determination by the determining means when the detected fuel concentration is larger than a reference value. The self-diagnosis apparatus for an engine according to claim 1, wherein the fuel concentration detecting means comprises a fuel concentration sensor for detecting a fuel concentration in engine oil. 2. The self-diagnosis apparatus of an engine according to claim 1, wherein the fuel concentration detecting means is configured to determine the fuel concentration from the fuel concentration estimation value calculated based on the addition and subtraction values of the fuel concentration determined in accordance with the engine operating state. .