JPS6073022A - Controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve fuel consumption and emission by prohibiting air-fuel ratio feedback control when anomaly is generated in the output signal of an O2 sensor for detecting the concentration of exygen. CONSTITUTION:An O2 sensor 13 for detecting the concentration of oxygen in the exhaust pipe of an internal-combustion engine 1 is provided. Comparators 16 and 17 compare the outputs of low-pass filters 14 and 15 with an activity judging level L1 and a rich/lean judging level L2 respectively, and during the time when each output signal of the low-pass filters 14 and 15 is larger, each output signal (a), (b) is 1. When it is judged that the output signal (a) becomes 1, and active state is formed, and the output signal (b) is zero, it is judged that the output signal of the O2 sensor 13 is anomalous, and air-fuel ratio feedback control is prohibited. Thus, fuel consumption and emission can be kept in desirable state.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a control device for an internal combustion engine that performs air-fuel ratio feedback control based on the detection result of an 02 sensor that detects oxygen concentration, and brings the actual air-fuel ratio closer to the stoichiometric air-fuel ratio. I can buy things.

Prior Art and Problems Conventionally, an 02 sensor is provided to detect the oxygen concentration contained in the exhaust gas of an internal combustion engine, and based on the detection result of the 02 sensor, it is determined whether the air-fuel ratio is in a rich state or a lean state. Based on the judgment result, air-fuel ratio feedback control is performed to bring the actual air-fuel ratio closer to the stoichiometric air-fuel ratio.

Figure 1 shows the relationship between the state of the air-fuel ratio A/F and the change state of the air-fuel ratio correction coefficient FAF. Skip the fuel ratio correction coefficient FAF by a certain amount.

After increasing the air-fuel ratio A/F, decrease it at a predetermined slope, and
When the engine is in a lean state, the air-fuel ratio correction coefficient FAF is skipped by a certain amount and then increased at a predetermined slope.

By the way, since the fuel injection amount TAU is calculated by multiplying the basic injection amount TP by the air-fuel ratio correction coefficient FAF, it is important to change the air-fuel ratio correction coefficient FAF as described above. The air-fuel ratio can be brought close to the stoichiometric air-fuel ratio.

By performing such air-fuel ratio feedback control, it is possible to maintain good emissions and fuel efficiency, but
It had the following drawbacks. In other words, due to aging etc.
If an abnormality occurs in the sensor, or if there is a poor contact with the ground of the 02 sensor, the judgment result as to whether the air-fuel ratio, 4/F, is in a rich state or in a single state may be incorrect. However, if the air-fuel ratio feed ratio correction was performed based on this incorrect judgment result, the fuel injection amount TAU would increase in the rich state, and the fuel injection amount TAU would increase in the lean state. This has the drawback of causing a decrease in f, which has a negative effect on emissions and the air-fuel ratio.

Purpose of the Invention The present invention has been made to improve the above-mentioned drawbacks, and the seventh purpose is to inhibit the air-fuel ratio feedback correction when an abnormality occurs in the output signal of the 02 sensor, thereby preventing an adverse effect on emissions and the air-fuel ratio. The goal is to prevent this from happening.

Based on the output signal of the O2 sensor 100, the determining means 101 determines whether or not an abnormality has occurred in the output signal of the O2 sensor 100. The control means 102 determines that the determination means 101 is 0.
If it is determined that an abnormality has occurred in the output signals of the two sensors, air-fuel ratio feedback control is prohibited.

Embodiment of the Invention FIG. 3 is a block diagram of an embodiment of the invention. 5.1 is an internal combustion engine, 2 is an air cleaner, 3 is an air flow meter,
4 is a throttle chamber, 5 is an intake manifold, 6 is an injector, 7 is a throttle valve, 8 is a microprocessor, 9 is a data input section, 10 is a data output section,
11 is a memory, 12 is a water temperature sensor that detects the temperature of cooling water, 13 is an 02 sensor that detects the oxygen concentration in the exhaust pipe of the internal combustion engine 1, and 14 and 15 are low-pass filters that remove noise from the output signal of the 02 sensor. Since the frequency of the output signals of the hb and o2 sensors is approximately 0.3 to 3H2, the cutoff frequency is set to 10H2. 16.1
7 are the output signals of the low-pass filters 14 and 15 and the activation determination level L1. IJette/Lean judgment level L2
The output signals α and b of the low-pass filters 14 and 15 are set to "1" while the output signals of the low-pass filters 14 and 15 are larger. Note that the activity determination level L1 and the lean/rich determination level L2 are set to have a relationship of Ll>L2.

Intake air flows from the air cleaner 2 to the shear flow meter 6, to the throttle chamber 4f, and then to the intake manifold 5.
The fuel is supplied to each branch and each cylinder, and the fuel is injected by an injector 6.

Further, the flow of intake air is controlled by a throttle valve 7 that is linked to an accelerator pedal.

Further, FIG. 4 is a flowchart showing the processing contents of the microprocessor 8, and the operation of FIG. 3 will be explained below with reference to FIG.

In step S, the microprocessor 8 first determines whether the output signal α of the comparator 16 has become "1" or not.
If it is determined that the 02 sensor 13 has become "1", it is assumed that the 02 sensor 13 has become active and the process of step S2 is performed.

In step S2, it is determined whether the signal α is necessarily “1” or not, and if it is determined that α = “1”, it is determined whether the output signal of the comparator 17 is necessarily “1” or not. Step E15
), if it is determined that b = “0”, the 02 sensor 13
It is determined that there is an abnormality in the output signal of
Ffr1'' and prohibits air-fuel ratio feedback control. That is, when a ground contact failure occurs in the 02 sensor 13, the output signal of the 02 sensor 13 will be as shown in Fig. 5 (A).
Also, low pass filter 14.15 as shown in pl
Due to the difference in the charging and discharging time constants of the output signals c and d of the halo pass filter 14 and 15, as shown in the same figure (B), when the signal C is p greater than the activation level L1, the signal d becomes active. It may be p smaller than level L2. In such a case, the output signals α and 6 of the comparators 16 and 17 are “1” and “0”, so the microprocessor 8 determines in steps S2 and S3 that the signals α and b are “1#” and “MQH”, respectively. If it is determined that an abnormality has occurred in the output signal of the 02 sensor, the process of step S4 is performed and air-fuel ratio feedback control is prohibited.

If the determination result in step S2 is No, or if the determination result in step S2 is YES and the determination result in step S3 is YES, the microprocessor 8 determines that the count value CE of the internal counter B is equal to or greater than a certain value KB. It is determined whether or not it will appear (step S5). As will be seen later, the count value CB of the counter B is calculated by the comparator 17.
If the P1 microprocessor 8 determines in step S5 that CB≧KB, it is assumed that an abnormality has occurred in the Q2 sensor 13. The process of step S4 is performed to prohibit air-fuel ratio feedback control. If it is determined that CE<KE, the microprocessor 8 determines whether the state of the internal combustion engine satisfies air-fuel ratio feedback control execution conditions (F/B conditions) (step S6).

The determination as to whether the F/B condition is satisfied is made by, for example, determining that the F/E condition is satisfied if the cooling water temperature is equal to or higher than a predetermined temperature based on the detection result of the water temperature sensor 12. If it is below the temperature, it is determined that the F/B conditions are not satisfied.

If it is determined that the F/B conditions are not satisfied, the count value CA of counter A is set to "0" and step calculation (step 515) and injection control (step 516) are performed.
After this, the process returns to step S2.

Note that the counter A is provided inside the microprocessor 8 and counts an internal clock. Also, F
If it is determined that the /B condition is satisfied, the microprocessor 8 makes a full judgment as to whether or not the value of the signal S in the current processing cycle matches the value of the signal S in the previous processing cycle. (Step S9).

If it is determined that they do not match, the microprocessor 8 determines whether the count value CA of the color/res A is greater than or equal to a certain value KA (step 810 ), and if it is determined that CA<KA and δ, the comparator 17 Assuming that the frequency of the output signal S is higher than a predetermined value, the count value CE of counter B is +
First, step 511), and then set the count value CA of counter A to "0" (step 513). Also, CA
If it is determined that ≧KA, the count value CB of the counter B is set to "0" (step 512), and then the count value CA of the counter A is set to "0" (step 512),
Next, the air-fuel ratio correction coefficient FAF can be requested (step 51).
4). Next, the microprocessor 8 calculates the air-fuel ratio correction coefficient F.
The fuel injection amount TAU is determined based on the AF and the basic injection amount TP (step S15), and then injection control is performed based on the fuel injection amount TAU determined in step S15 (step 516). After this, the process of step S2 is performed. It returns to

As described in detail, the present invention prohibits air-fuel ratio feedback control when an abnormality occurs in the output signal of the 02 sensor. It also has the advantage of maintaining good fuel efficiency and emissions compared to conventional equipment.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the air-fuel ratio state and the air-fuel ratio correction coefficient, Fig. 2 is a block diagram of the present invention, Fig. 6 is a block diagram of an embodiment of the present invention, and Fig. 4 is a microprocessor. 8 is a flowchart showing the processing contents, and FIG. 5 is a waveform diagram of signals of each part of the device. 1 is an internal combustion engine, 2 is an air cleaner, 3 is an air flow no. 1', 4U throttle valve, 5U intake manifold, 6 is an injector, 7 is a throttle valve, 8 is a microprocessor, 9 is a data input unit, 10 is data Output part, 11 is memo IJ, 12 is water temperature sensor, 16 is 0
2 sensors, 14.15 is Ronos filter, 16.1
7 is a comparator, 101 is a judgment means, and 102 is a control means. Patent Applicant Fujitsu Ten Ltd. Representative Patent Attorney Gobe Tamamushi (1 other person) Figure 1 Figure 2 Figure 5 Figure 3

Claims (1)

[Claims] Equipped with an 02 sensor that outputs a signal corresponding to oxygen concentration,
In an internal combustion engine control device that performs air-fuel ratio foot check control to bring an actual air-fuel ratio closer to the stoichiometric air-fuel ratio based on the detection result of the 02 sensor, there is a control device that compares the output signal of the 02 sensor at a predetermined level. 1 comparison means and the 0
a second comparing means for comparing the output signals of the two sensors at predetermined levels; a first determining means for determining that there is an abnormality based on the logic of the first and second comparing means; and the first comparing means. Alternatively, a second determining means determines that there is an abnormality when the output of the second comparing means is higher than a predetermined frequency, and the first determining means or the second determining means detects the output of the 02 sensor. 1. A control device for an internal combustion engine, comprising: control means for prohibiting air-fuel ratio feedback control when it is determined that there is an abnormality in the internal combustion engine.