JPS606036A - Air-fuel ratio controller of engine - Google Patents

Abstract

PURPOSE:To enable control of a sensor during operation in other air-fuel ratio than a theoretical air-fuel ratio, by a method wherein exhaust gas is introduced in a gap between an oxygen sensor of a flat electrolyte and an oxygen pump which are positioned opposite to each other, and an air-fuel ratio is detected by means of the output of a pump current which keeps the electromotive force of a sensor at a given value. CONSTITUTION:An amount of suction gas sucked is detected by a sucked air amount detecting device 4, an electronic controller 11, inputting an output signal therefrom, drives a fuel feed valve 5, and the fuel proportioning a sucked air amount is fed. In which case, by means of an output signal proportioning the pump current of an oxygen pump, the air-fuel ratio of an engine is detected. For example, in the operating condition of an engine 1 determined by means of the output signal of the sucked air amount detecting device 4 and the output signal of a number of revolutions detector 10, in case an operating air-fuel ratio is 12, an electromotive force (e) is kept at 60mV, and an amount of the fuel injected and fed from a fuel feed valve 5 is controlled by a controller 11 so that a pump current Ip of an air-fuel ratio sensor 8 is 80mV. Further, in case an air-fuel ratio is desired to be 14, the electromotive force (e) may be 100mV. This enables to perform feedback control by means of an air-fuel ratio sensor even if operation is effected in other air-fuel ratio than a theoretical air-fuel ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device for an engine for a private vehicle, and in particular, a flat solid type oxygen sensor and a solid electrolyte oxygen pump are arranged opposite to each other with a very small gap therebetween. The configuration is such that all of the exhaust gas from the engine is introduced into the gap, and an output signal corresponding to the pumping current of the oxygen pump necessary to maintain the entire electromotive force generated by the oxygen sensor at a predetermined value is applied to the exhaust gas of the engine. A fuel ratio sensor configured to detect the fuel ratio and a means for changing the electromotive force of the oxygen sensor maintained at the predetermined value f' according to the operating condition of the engine are provided, and the operating air fuel ratio of the engine can be adjusted to any desired value. The present invention provides all engine air-fuel ratio control devices that can provide feedback control to the engine air-fuel ratio.

Conventionally, an e-cumulative sensor composed of an ion-conductive solid electrolyte (e.g. stabilized zirconia) is used to detect the stoichiometric air-fuel ratio by changing the electromotive force caused by the difference between the oxygen partial pressure of the exhaust gas and the oxygen partial pressure of the air. As is well known, it is possible to detect the combustion state of a motor vehicle and control the engine of a motor vehicle, for example, rather than operating it at the stoichiometric air-fuel ratio. By the way, the above oxygen sensor has an air-fuel ratio (A/
When F) is at the stoichiometric air-fuel ratio of 14.7, a large change in output is obtained, but there is almost no change in other air-fuel ratio ranges. However, there is rarely the problem that the cutting edge of the oxygen sensor cannot be utilized.This invention provides an air-fuel ratio control device for an engine that is capable of feedback control using an air-fuel ratio sensor when operating at an air-fuel ratio other than the stoichiometric air-fuel ratio. It is something that provides.

An embodiment of the present invention shown in the drawings will be described below. FIG. 1 is a configuration diagram showing an embodiment of the present invention, and in the figure (
1) is the engine, (2) is the intake pipe of the engine il+, -' +
31, 1 liter, +41ri, an intake air amount detection device that detects the total amount of intake nitrogen sucked into the engine (1), 15
) is a fuel supply valve provided upstream of the throttle box (3), (6) is an air cleaner provided upstream of the intake air detection device 14+, and (7) is a fuel supply valve provided upstream of the throttle box (3).
+ exhaust pipe, (8) is the air-fuel ratio sensor attached to the exhaust pipe (7), (9) is the air-fuel ratio detection electronic device, (101 is the rotation speed detector of the engine (1), urz the rotation The output signals of the rotation speed detector 0), the intake air amount detection device 14+, and the air-fuel ratio detection electronic device @(9) are input, and the fuel supply 5P+61 is fully driven in accordance with these input information, and the engine ( 1) This is an electronic control device that controls the fuel supply. This electronic control device σ1] is the air-fuel ratio detection unit @
(9) It also has a function to change the reference voltage (VR) according to all the above input information. Figure 2 shows the above air-fuel ratio sensor (
8) The details of the fuel ratio detection device (9) are shown in the detailed configuration diagram A, and the sectional view taken along line II-II in FIG. 3, 1l-J: FIG. In the figure - Air-fuel ratio sensor f81 U thickness is approximately Q,
Platinum 'WL pole circles and 09 are provided on both sides H of a 5 n1m flat plate-shaped ion-conductive solid electrolyte (stabilized zirconia) σ&, and nitric acid is applied to the fC solid electrolyte oxygen pump αG, in the same way as the oxygen pump aa. A solid electrolyte oxygen sensor (
7) and the above oxygen pump 0υ and the above oxygen sensor g! The kites are mounted on support stands (CI) for facing each other with a micro gap of 0.1 mm pj and dk. The oxygen sensor (7) is connected to the air-fuel ratio detection electronic device (9) at the electrode U.
The electromotive force (e) generated between 8I101 is connected to the resistor (R1).
The operational amplifier is applied to the inverting input terminal of the operational amplifier N through By the output of (4), the transistor (TR)
(C drive the electrode a4.cts of the oxygen pump αG)
It has a function to control the flow (IF) of the pump 11L flowing in between. In other words, it functions to supply the electromotive force (e) - the foot value (the pump current CIF necessary to maintain the V illusion). Also, the reference voltage (VR) is the engine +11
p is changed to the required value by the above-mentioned electronic control "1") according to the operating state of p.

And the pump current (
Resistor (RO) to obtain the output frequency corresponding to IP)
Fully equipped. A desired resistance value is selected for this resistor (RO) so that the pump current (IP) does not flow excessively in correspondence with the DC power source. (C) I'! Fig. 4 is a characteristic diagram obtained by testing the air-fuel ratio sensor (8) shown in Fig. 2 above by installing it in a 2000° zero engine engine for domestically produced passenger cars. If an excessive pump X flow (IF) flows, the oxygen pump 00 will be destroyed, so the pump current (1, P) is limited by the @ flow power source (B) so that it does not flow more than 100 mA. By changing the reference voltage (V R), the electromotive force (eJl 20(
1) This shows the change in the above bong'#L group (IF) when the air-fuel ratio (A/F) Y of the above machine 19.1 was changed while keeping them at 71V, 100mV, and somv-60mV. Electric power (eJf: When kept at goom'v, pumping is possible at the stoichiometric air-fuel ratio of 14.7, but the flow (IP) changes rapidly.If the electromotive force (e) is decreased, the air-fuel ratio is much smaller than the stoichiometric wall-fuel ratio. In the fuel ratio range, the pump current (IF) changes in proportion to the air-fuel ratio.This invention utilizes the 1° characteristic shown in FIG. The operation of this inventive device will now be explained.

When the machine (1) is started, the intake air drawn into the engine il+ is introduced from the atmosphere into the air cleaner (6), and the intake air is detected by the detection device (4), and its suction chamber is detected.
Intake air 1 (passes through 2- and is introduced into the engine).The electronic control unit (to which all output signals from the intake air detection device 4! is input)
ill fully drives the fuel supply valve 15i to inject and supply fuel corresponding to the intake air to the engine (1). When operating the engine il+ at the stoichiometric air-fuel ratio based on the output signal of the air-fuel ratio detection electronic device (9), the electronic control device σ1] controls the air-fuel ratio detection electronic device (9).
) to maintain the electromotive force (e) generated by the oxygen sensor (4) at 200 mVK. the result,
Due to the characteristics shown in Figure 4, the blade signal (pump current) from the air-fuel ratio sensor (8) changes rapidly at the stoichiometric air-fuel ratio of 14.7. Feedback control is performed at the engine il+'5 stoichiometric air-fuel ratio. Next, the above-mentioned intake air amount detection device (
In the operating state of the engine tl+, which is calculated by the output signal of 4) and the cutting edge signal of the rotation speed detector (10), when the operating air-fuel ratio is, for example, 12, the electromotive force (@) f
Control the amount of fuel injected from the fuel supply ff+51 to the electronic control device (11) so that the pump current (IF) of the nitrous fuel ratio sensor (8) becomes 60 mV, for example, 80 mA. Then, if you want to set the operating air-fuel ratio to 14, the electromotive force (e) 'fc100m
All you have to do is change the VKf.

As described above, the present invention arranges a solid electrolyte oxygen sensor, which is configured by providing electrodes on both sides of a flat solid electrolyte, and a solid cage Mη oxygen pump, facing each other through a minute gap, and an engine is installed in this gap. In addition to introducing all the exhaust gas, the fuel-fuel ratio of the engine is determined by a signal corresponding to the pump current of the oxygen pump necessary to maintain the electromotive force generated by the oxygen sensor at the required value. Equipped with an air-fuel ratio sensor that detects all of the air-fuel ratios, it maintains the above 7F'r value, and has means to change the oxygen sensor according to the operating condition of the engine and corresponds to the 10 bomb currents. The output signal becomes the desired value. J: Since the above engine is equipped with a means for controlling the amount of fuel supplied to the engine, the air-fuel ratio of the engine can be controlled by feedback control using the air-fuel ratio sensor when operating at an air-fuel ratio other than the stoichiometric air-fuel ratio of 9. A new control device has been developed that allows for more precise air-fuel ratio control than conventional open control.

In the above explanation, the amount of fuel supplied to the engine is controlled when the pump current corresponding to the pump current reaches the desired value. A similar effect can be obtained by controlling Ken.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of the flow of the present invention, Fig. 2 is a wg diagram showing an example of an air-fuel ratio sensor used in the device of this invention, and Fig. 3 is a diagram showing ■-■ of Fig. 2. Section (3) along the line,
FIG. 4 is a characteristic diagram of the air-fuel ratio sensor of FIG. 2. In the figure, (1) is the engine, 141 is the intake air amount detection device, 15) is the fuel supply valve, ill rX, exhaust pipe, (8)
) is the air-fuel ratio sensor, (ill is the electronic control unit, a5 is the solid electrolyte rR pump, and gJ is the solid electrolyte oxygen sensor. Agent: Masuo Oiwa)

Claims (1)

[Claims] A solid electrolyte oxygen sensor and a solid electrolyte oxygen pump are fabricated by providing electrodes on both sides of a flat solid electrolyte. and is configured to introduce all of the exhaust gas of the engine into the gap, and also by a de-blade signal corresponding to the pump 'II flow of the oxygen pump necessary to maintain the electromotive force generated by the oxygen sensor at a predetermined value. It is equipped with an air-fuel ratio sensor for detecting the air-fuel ratio of the engine, a means for changing the electromotive force of the oxygen sensor, which is kept at the predetermined value, according to the operating state of the engine, and a means for changing the electromotive force of the oxygen sensor, which is kept at the predetermined value, according to the operating state of the engine, and An air-fuel ratio control device for an engine, comprising means for controlling the amount of fuel and air type supplied to the engine so that the output signal becomes a desired value.