JP2508676B2 - Oxygen concentration detector for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen concentration detection device for an internal combustion engine, and more particularly to an expensive oxygen sensor that calculates the oxygen concentration based on the output signal of an air-fuel ratio sensor instead of the oxygen sensor. The present invention relates to an oxygen concentration detection device for an internal combustion engine, which eliminates the need for reducing the cost and improves the accuracy of the oxygen enrichment control.

[Conventional technology]

Conventionally, an oxygen enrichment device for an internal combustion engine supplies oxygen enriched air whose oxygen concentration in the air is increased by an oxygen concentrating device to the internal combustion engine to improve combustion efficiency and output / fuel consumption rate. . Further, in order to generate the oxygen-enriched air, it is necessary to cause a pressure difference between the upstream side and the downstream side of the oxygen concentrator, and in order to cause this pressure difference, the oxygen concentrator is supplied with a feed pump. There is one in which air is supplied and at the same time, oxygen-enriched air generated by an oxygen concentrator is supplied into an internal combustion engine as supercharged air by a suction pump (Japanese Patent Laid-Open No. 58-143119).

[Problems to be solved by the invention]

By the way, in the conventional oxygen concentration detection apparatus for an internal combustion engine, an oxygen sensor is provided in the intake system of the internal combustion engine, and the oxygen concentration of intake air is detected by the detection signal of this oxygen sensor.

Therefore, it is necessary to provide an expensive oxygen sensor in the intake system of the internal combustion engine, resulting in high cost, economically disadvantageous, complicated structure, and difficult to manufacture.

[Object of the Invention]

Therefore, an object of the present invention is, in order to eliminate the above-mentioned inconvenience, a fuel injection in which a combustion injection amount is determined by an intake air amount of oxygen-enriched air measured by an air flow sensor provided in an intake passage of an internal combustion engine having an oxygen concentrator. In addition to providing the amount determination unit, a correction control unit that performs feedback correction control of the air-fuel ratio by the output signal of the air-fuel ratio sensor provided in the exhaust passage is provided, and the fuel injection amount from the fuel injection amount determination unit and the output signal of the air-fuel ratio sensor are provided. By providing an oxygen concentration calculation unit that calculates the oxygen concentration by inputting the output signal of the air flow sensor, the oxygen concentration can be calculated by the output signal of the air-fuel ratio sensor instead of the oxygen sensor, making an expensive oxygen sensor unnecessary. Detecting the oxygen concentration of an internal combustion engine, which can reduce the cost, is economically advantageous, and can improve the accuracy in the oxygen enrichment control. There in order to realize the location.

[Means for solving problems]

To achieve this object, the present invention provides a fuel injection amount determination unit that determines a fuel injection amount based on an intake air amount of oxygen-enriched air measured by an air flow sensor provided in an intake passage of an internal combustion engine having an oxygen concentrator. A correction control unit for feedback-correcting the air-fuel ratio based on the output signal of the air-fuel ratio sensor provided in the exhaust passage is provided, and the fuel injection amount from the fuel injection amount determination unit, the output signal of the air-fuel ratio sensor, and the air flow sensor are provided. And an oxygen concentration calculator for calculating the oxygen concentration by inputting the output signal of the above.

[Action]

With the configuration as described above, the oxygen concentration is calculated by inputting the fuel injection amount from the fuel injection amount determination unit, the output signal of the air-fuel ratio sensor and the output signal of the air flow sensor to the oxygen concentration calculation unit. Yes, the output signal of the air-fuel ratio sensor can be used instead of the oxygen sensor, an expensive oxygen sensor is not required, the cost can be reduced, and the accuracy in oxygen enrichment control can be improved. There is.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 4 show an embodiment of the present invention. In FIG. 1, 2 is an oxygen concentration detecting device for an internal combustion engine, 4 is an intake passage, 6 is a throttle body, 8 is an injector,
10 is an engine, 12 is an exhaust passage, and 14 is a muffler.

The oxygen concentration detecting device 2 has an oxygen concentrating device (not shown) for supplying oxygen-enriched air to the intake system, and an oxygen-enriching film is provided in the oxygen concentrating device. An air flow sensor 16 is provided in the intake passage 4 downstream of the oxygen concentrator, and the injector 8 for injecting fuel into the intake system is provided.

Further, an air-fuel ratio sensor (hereinafter referred to as an A / F sensor) 18 for detecting an air-fuel ratio of the exhaust system is provided in the middle of the exhaust passage 12, and a rotation sensor 20 for detecting an engine speed is provided in the engine 10.

The air flow sensor 16 and the injector 8 measure a intake air amount of oxygen-enriched air and determine a fuel injection amount based on the measured value.
Connect. Further, the A / F sensor 18 is provided with a correction control unit 24 for feedback correction control of the air-fuel ratio to the target air-fuel ratio by PI (proportional component-integral ratio) control.

Further, an oxygen concentration calculation unit 26 is connected to the fuel injection amount determination unit 22 and the A / F sensor 18, and these fuel injection amount determination unit 22
The oxygen concentration calculation unit 26 is configured to calculate the oxygen concentration by inputting the fuel injection amount from the A / F sensor 18, the output signal of the A / F sensor 18, and the output signal of the air flow sensor 16.

More specifically, the oxygen concentration calculation unit 26 includes an intake air amount by the air flow sensor 16, a fuel injection amount, an engine speed by the rotation sensor 20, and the A / F sensor 1.
The output signal from 8 is input to control so as to calculate the oxygen concentration.

In addition, the oxygen concentration calculation unit 26 uses the injector 8
It is configured to calculate the oxygen concentration in consideration of the delay time from the input time of to the output time of the A / F sensor 18.

The transmission coefficient, which is the delay time, is as shown in FIG.
Dead time system controlled by engine speed and A / F sensor 1
It is divided into a first-order lag system, which is a characteristic of No. 8, and a dead time system consisting of the dead time L of the engine 10 from the time when the input time of the injector 8 is fixed until the time when the output of the A / F sensor 18 is fixed. Delay time e ^-LS and delay time of primary delay system consisting of time constant T of A / F sensor 18 Occurs.

Next, an explanation will be given along the flowchart for interruption of FIG.

In the interrupt (ICI) for each engine revolution, the engine speed N _E is first detected (100) by the rotation sensor 20, and the detected engine speed N _E and the delay T _DAF of the A / F sensor 18 are detected. By Then, the delay time T _D is calculated (102).

Then, this interrupt (ICI) is interrupted by a feedback correction control flowchart (not shown) for each engine revolution, and the delay time T _D is calculated.

Further, description will be given along the interrupt flowchart of FIG.

The air flow sensor 16 detects the intake air amount M _A, and also detects the fuel amount M _F which is the fuel injection amount determined by the intake air amount M _A (200), and sets the detected intake air amount M _A. Intake air amount M _AM and detected fuel amount M
Judgment whether _F is equal to the set fuel amount M _FM (202)
I do.

At this time, the determination (202) is to set the intake air amount M _A and the fuel amount M _F to the preset intake air amount M _AM and the set fuel amount M _FM in advance, for example, when the air flow sensor 16 fails. The abnormal signal output to is eliminated.

When the determination (202) is NO, the time counter C
_{In addition} to resetting _T , intake air amount M _A and fuel amount M
_F is feedback-corrected to the set intake air amount M _AM and the set fuel amount M _FM , respectively (204), and the process returns to the detection of the intake air amount M _A and the fuel amount M _F (200).

Further, the setting and the intake air amount M _A of the aforementioned intake air amount M _AM, and the fuel quantity M _F and setting a fuel quantity M _FM Togaotto s equal determines whether (202) If YES, the time counter C _T
Determines whether or not the delay time is equal to or longer than the delay time T _D calculated by the interrupt (ICI) for each engine revolution (206).

At this time, the judgment (206) judges whether the time counter C _T is within the allowable range by setting the allowable range as the delay time T _D.

Then, if the judgment (206) as to whether or not the time counter C _T is the delay time T _D or more, is NO, the time counter C _T is incremented by 1 to obtain a new time counter C _T (208), Return to detection of intake air amount M _A and fuel amount M _F (200).

Further, if the determination (206) as to whether the time counter C _T is equal to or longer than the delay time T _D is YES, the A / F sensor 18 detects the air-fuel ratio (A / F) (210). Then, the oxygen concentration (weight ratio) is calculated by the following equation (212).

That is, the oxygen amount M _O2 is obtained by the formula of air-fuel ratio × fuel amount M _F × k, and the oxygen concentration (weight ratio) is obtained by dividing this oxygen amount M _O2 by the intake air amount M _A. . Note that k in the formula is a weight ratio of oxygen in general air.

The flow chart shown in FIG. 4 is for interrupting a feedback correction control flow chart (not shown) every 10 ms to obtain the oxygen concentration (weight ratio) of the oxygen-enriched air.

As a result, the oxygen concentration can be calculated by the output signal of the air-fuel ratio sensor instead of the oxygen sensor, and it is not necessary to provide an expensive oxygen sensor on the intake side, and the cost can be reduced, which is economically advantageous. The structure can be simplified, the manufacturing is easy, and it is practically advantageous.

In addition, since the oxygen concentration can be calculated from the output signal of the air-fuel ratio sensor, it becomes possible to control the oxygen-enriched film,
The accuracy in controlling the oxygen enrichment amount can be improved.

〔The invention's effect〕

As described in detail above, according to the present invention, the fuel injection amount determination unit that determines the fuel injection amount by the intake air amount of the oxygen-enriched air measured by the air flow sensor provided in the intake passage of the internal combustion engine having the oxygen concentrator. And a correction control unit that performs feedback correction control of the air-fuel ratio by the output signal of the air-fuel ratio sensor installed in the exhaust passage,
Since the oxygen concentration calculation unit for calculating the oxygen concentration by inputting the fuel injection amount from the fuel injection amount determination unit, the output signal of the air-fuel ratio sensor, and the output signal of the air flow sensor is provided, instead of the oxygen sensor, the air-fuel ratio sensor The oxygen concentration can be calculated from the output signal, and it is not necessary to provide an expensive oxygen sensor on the suction side, which can reduce the cost and is economically advantageous.
In addition, the structure of the oxygen concentration detection device for the internal combustion engine can be simplified, the manufacture becomes easy, and it is practically advantageous. Furthermore, since the oxygen concentration can be calculated from the output signal of the air-fuel ratio sensor, the oxygen enriched film can be controlled, and the accuracy in controlling the oxygen enriched amount can be improved.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a schematic explanatory view of an oxygen concentration detection device for an internal combustion engine, FIG. 2 is an explanatory view of a transfer coefficient which is a delay time, and FIG. 3 is an engine 1 FIG. 4 is a diagram showing an interruption flowchart for each rotation, and FIG. 4 is a diagram showing an interruption flowchart for every 10 ms. In the figure, 2 is an oxygen enrichment device for an internal combustion engine, 4 is an intake passage, 6 is a throttle body, 8 is an injector, 10 is an engine, 12 is an exhaust passage, 14 is a muffler, 16 is an air flow sensor, 18 is an air-fuel ratio. A sensor (A / F sensor), 20 is a rotation sensor, 22 is a fuel injection amount determination unit, 24 is a correction control unit, and 26 is an oxygen concentration calculation unit.

Claims (2)

(57) [Claims] 1. A fuel injection amount determining unit for determining a fuel injection amount based on an intake air amount of oxygen-enriched air measured by an air flow sensor provided in an intake passage of an internal combustion engine having an oxygen concentrator, and provided in an exhaust passage. A correction control unit that performs feedback correction control of the air-fuel ratio based on the output signal of the air-fuel ratio sensor is provided, and the fuel injection amount from the fuel injection amount determination unit, the output signal of the air-fuel ratio sensor, and the output signal of the air flow sensor are input. An oxygen concentration detecting device for an internal combustion engine, comprising an oxygen concentration calculating unit for calculating an oxygen concentration. 2. The oxygen concentration calculation unit according to claim 1, wherein the oxygen concentration calculation unit is an oxygen concentration calculation unit that calculates the oxygen concentration in consideration of the delay time from the injector input timing to the air-fuel ratio sensor output timing. Oxygen concentration detector for internal combustion engine.