JPS6245951A - Air-fuel ratio controller - Google Patents

Abstract

PURPOSE:To make the working conditions of an air-fuel ratio controller observable from the outside as well as to facilitate its inspection, maintenance, etc., by installing a monitor outputting device which adds output of an air-fuel ratio sensor to as air-fuel ratio control signal and outputs the value to the outside. CONSTITUTION:In case of an air-fuel ratio controller 20 which controls the opening time of a fuel injection valve 12 properly on the basis of output of an oxygen sensor 10 and performs air-fuel ratio feedback control operating an engine 2 under the specified air-fuel ratio, first of all, it is judged that an air-fuel ratio control signal exists in which side among the trisected signal ranges being securable as the air-fuel ratio control signal at the time of a monitor output process. Next, an output state of the oxygen sensor 10 is judged, and when the output is 'L', a duty ratio signal necessary for outputting reference voltage values VI and VII or VIII set according to each range in advance from an integration circuit 28 is outputted. And, output of a monitor outputting terminal 22 is observed whereby the working conditions of the air-fuel ratio controller 20 are found out.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an air-fuel ratio control device for an internal combustion engine, and particularly to an air-fuel ratio control device that allows the operating status of the air-fuel ratio control device to be observed from the outside. be.

[Conventional technology] Conventionally, when operating an internal combustion engine, fuel efficiency and emissions = 1
- Executes air-fuel ratio control that strictly adjusts the air-fuel ratio in order to improve the air-fuel ratio. This normally uses an air-fuel ratio sensor, in this case an oxygen sensor, that compares the residual oxygen concentration in the exhaust gas of an internal combustion engine with a predetermined value and detects whether the actual air-fuel ratio is higher or lighter than the predetermined air-fuel ratio. and,
Based on this oxygen sensor output, for example, the amount of fuel supplied to the internal combustion engine is adjusted, making it possible to always operate the internal combustion engine under the optimum air-fuel ratio.

The air-fuel ratio control device that executes the above-mentioned control is constructed using an electronic control device that has made significant progress in recent years, and ensures high responsiveness and reliability. However, on the other hand, since all of its operations are converted into electrical signals and processed, it is impossible to observe them from the outside, making it difficult to know the operating status of the air-fuel ratio control device.

Therefore, in recent years, it has been proposed to add a terminal for outputting an output signal to the outside of the above-mentioned air-fuel ratio control device, thereby making it possible to monitor the operating status of the air-fuel ratio control device. For example, according to Utility Model Application Publication No. 54-12-8020, the air-fuel ratio control signal output to the internal combustion engine is transmitted as is to the external output terminal, which is extremely useful for inspection and maintenance of the air-fuel ratio control device. Convenience is provided.

[Problems to be Solved by the Invention] However, the air-fuel ratio control device as described above is still not satisfactory and has the following problems.

In order to accurately and quickly monitor the operating status of the air-fuel ratio control device, it is insufficient to simply observe the air-fuel ratio control signal output to the internal combustion engine as described above. That is,
To determine whether the air-fuel ratio control device operates normally, firstly, whether the output of the air-fuel ratio sensor is normal or not, and secondly, the air-fuel ratio control signal that is output to the internal combustion engine based on that output. It is necessary to monitor two types of signals: whether it is normal or not. The operating status of the air-fuel ratio control device becomes clear only when two types of signals are observed: the air-fuel ratio sensor output signal, which is the input signal to the air-fuel ratio control device, and the air-fuel ratio control signal, which is the output signal of the air-fuel ratio control device. It becomes.

In addition, when outputting the two types of signals to the outside as described above, if separate output terminals are provided on the instep, it will be a big constraint on the hardware configuration of the air-fuel ratio control device. If two types of signals are to be output by switching the switch, a new switching device and switching operation will be required. Therefore, there has been a desire for a simple and inexpensive air-fuel ratio control device that does not impose any new restrictions.

The present invention was made in view of the above problems and demands, and it is possible to accurately and quickly observe the operating status of a single output terminal without requiring a separate switching device or operation. The purpose is to provide an excellent air-fuel ratio control device that can.

[Means for solving the problems] The means configured by the present invention to solve the above problems are as follows:
As shown in the basic configuration diagram of FIG. 1, based on the output of an air-fuel ratio sensor S that detects whether the air-fuel ratio of the internal combustion engine EG is far below a predetermined air-fuel ratio, the air-fuel ratio is controlled by the internal combustion engine EG. The air-fuel ratio control device that outputs a signal is characterized by comprising a monitor output means C1 that adds the output of the air-fuel ratio sensor S and the air-fuel ratio control signal output to the internal combustion engine EG and outputs the sum to the outside. Its gist is an air-fuel ratio control device.

[Function] The air-fuel ratio control device of the present invention includes a monitor output means C1 having the following function.

The air-fuel ratio control device controls the air-fuel ratio of the internal combustion engine EG by suitably processing the output of the air-fuel ratio sensor S, as in the conventional case. New information is created by adding the air-fuel ratio control signal to be output and the output signal of the air-fuel ratio sensor S, and is output to the outside.

The output of the air-fuel ratio sensor S is the comparison result between the predetermined air-fuel ratio and the actual air-fuel ratio of the internal combustion engine EG, =
5 - Binarized information indicating whether the actual air-fuel ratio is richer or leaner than the predetermined air-fuel ratio. On the other hand, internal combustion engine E
The air-fuel ratio control signal for G is determined in consideration of the output of the air-fuel ratio sensor S and other operating conditions of the internal combustion engine EG, and can take various values. In this way, the two types of signals are completely different and undergo unique changes. Therefore, it is easy to infer the above two types of states from new information obtained by adding these.

Note that the above air-fuel ratio control signal is represented by multiple voltage values,
For example, when it is within range A, voltage V^, range B (B
The difference between the two types of signals may be made clearer by using a normal information processing technique, such as expressing the voltage VB (V8≠VA) when the voltage is within AA).

EXAMPLES In order to explain the present invention more specifically, the present invention will be described in detail with reference to Examples.

[Example] FIG. 2 is a schematic configuration diagram of an internal combustion engine system equipped with an air-fuel ratio control device according to an example. As shown in the figure, as sensors for detecting the operating state of the four-cylinder engine 2, an intake temperature sensor 4, an air flow meter 6, and a throttle sensor 8 are installed in the intake system, and a predetermined residual oxygen concentration in the exhaust gas is installed in the exhaust system. An oxygen sensor 10 is provided to compare the value, and a rotation speed sensor 9 is provided on the crankshaft of the engine 2. The device that inputs the detection outputs of these various sensors is the air-fuel ratio controller! 20, the amount of fuel required to operate the engine 2 at the desired air-fuel ratio is calculated based on the input information, and the amount of fuel corresponding to the calculation result is provided to each cylinder of the engine 2. The fuel is injected and supplied from the fuel injection valve 12. Further, the monitor output terminal 22 provided in the air-fuel ratio control device 20 is used for externally observing the operating status of the air-fuel ratio control device 20, as will be described later.

Figure 3 is the above air-fuel ratio control I device! 20 is a block diagram showing information processing centered on 20.

As shown in the figure, the air-fuel ratio side m device 20 includes a fuel injection valve 12 that receives power from a power source B based on the output of the oxygen sensor 10.
The air-fuel ratio of the engine 2 is controlled by controlling the driving time of the engine. In the figure, reference numeral 24 digitizes signals from various sensors that detect the operating state of the engine 2, such as a comparison circuit that compares the output of the oxygen sensor 10 with a set value, the intake air temperature sensor 4, the air flow meter 6, and the throttle sensor 8. C
This is an input circuit that includes a multiplexer and the like that outputs to the PU25. The processing procedure of this air-fuel ratio control wave @20, that is, the program executed by the CPU 25, is stored in advance in the ROM 26, and the storage of temporary information generated in the processing process is executed by the RAM 27. Also,
28 is C by executing monitor output processing as described later.
When the PU 25 outputs an arbitrary duty signal, a known integration circuit 29 integrates the signal and generates a voltage waveform in accordance with the duty signal.
2 represents a drive circuit that, when input with the control signal No. 2, amplifies the signal and generates a drive signal necessary to actually drive the fuel injection valve 12.

This air-fuel ratio control device configured as described above performs air-fuel ratio feedback control to operate the engine 2 at a predetermined air-fuel ratio by appropriately adjusting the opening time of the fuel injection valve 12 based on the output of the oxygen sensor 10 as usual. , and when it is determined that the air-fuel ratio feedback control is inappropriate based on the outputs of various sensors, oven control of the air-fuel ratio or the like is selectively executed without being influenced by the output of the oxygen sensor 10.

Such air-fuel ratio control for the engine 2 is output as an air-fuel ratio control signal to the drive circuit 29, which drives the fuel injection valve 12 faithfully to the air-fuel ratio control signal to adjust the amount of fuel supplied to the engine 2. It will be done.

Figure 4(a) shows an example of such air-fuel ratio control.
, (b). (a) As shown in the figure, the output of the oxygen sensor 10 indicates whether the actual air-fuel ratio of the engine 2 is richer than the predetermined air-fuel ratio (signal "R") or 111iwj (signal "L"). Appears as a binary signal. Accordingly, the present air-fuel ratio control device 20 can output the air-fuel ratio control signal as shown in FIG.

−〇 − Furthermore, the air-fuel ratio side 611 of this embodiment! @20 executes monitor output processing simultaneously with the above air-fuel ratio control. FIG. 5 is a flowchart of the monitor output processing.

When the CPU 25 enters the processing of this routine, first the air-fuel ratio control signal (FIG. 4(b)) is read (step 100), and then it is determined in which range this signal falls (step 100). 110). Here, the range of the air-fuel ratio control signal is divided into three equal parts (1, n, II [
)L, and the air-fuel ratio control state can be determined based on which of these ranges the current air-fuel ratio control signal exists. Then, according to this judgment, if it is within the range T, step 120 is executed, if it is within the range ■, step 130 is executed, and if it is within the range ■, step 140 is executed.
is selected and executed. These steps 120.130
In step 140, the output state of the oxygen sensor 10 is determined, and if the output is rl-J, a reference voltage V1. V]I or V■
The duty ratio signals necessary for outputting -10= from the integrating circuit 28 are respectively output (steps 150, 160, 170>).

Meanwhile, in steps 120, 130, and 140, the oxygen sensor 10
When the output of is determined to be rRJ, LL −J=
Steps 180, 190, and 200 are executed in place of steps 150, 160, and 170, and the duty ratio signal necessary to output a voltage that is ΔV higher than the reference voltages VI, VII, and Vlff in each of the above ranges is generated. is revealed.

Through the monitor output processing as described above, the duty ratio signal corresponding to the air-fuel ratio control signal and the output of the oxygen sensor 1) 10 at that time is output to the integration circuit 28, and the output of the integration circuit 28 that integrates the signal of It appears as shown in Figure 4 (C). That is, if you observe the output of the monitor output terminal 22, (
C) A waveform as shown in the figure is obtained, and as is clear from this waveform, the air-fuel ratio control signal is within the current range of 1.
]T or ■, and whether the output of the oxygen sensor 10 at that time is [R1 or rLJ] can be determined very easily. 11. According to this embodiment, although the configuration is simple by adding a single output terminal called the monitor output terminal 22, it is difficult to judge the operating status of the air-fuel ratio control device 20. All necessary information can be easily obtained, and the air-fuel ratio control device 20 is economical and suitable for maintenance and novice use. However, since many internal combustion engines are now equipped with microcomputers to control their operating conditions, an easy improvement is to add a program with the simple algorithm shown in Figure 5 and have it process. The configuration of this embodiment can be completed with just this step.

FIG. 6 is a flowchart h of a monitor output routine of another embodiment, which can be applied to an air-fuel ratio control device having the same structure as that of the previous embodiment. In the above embodiment, the value (ΔV) is determined according to the output of the oxygen sensor 10 using the air-fuel ratio control signal as a reference.
However, in this embodiment, the voltage (with respect to the output of the oxygen sensor 10 as a reference) is
VL.

VR) to the range of the air-fuel ratio control signal (1, H, II[>
Add the voltages (ΔVI, ΔV■, ΔVII[) according to -
An example of obtaining a monitor output of 12= will be explained.

When the process of the monitor output routine of this embodiment is started,
In step 300, the current output of the oxygen sensor 10 and the air-fuel ratio control signal are read, and then the output of the oxygen sensor 10 is "R".

rLJ (step 310)
. Here, if the output of the oxygen sensor 10 is rLJ, step 320 is executed, and if the output is rRJ, step 330 is executed.
is selected and executed. Steps 320 and 330 are for determining in which range (I, n, I) the air-fuel ratio control signal exists, and the process branches into three depending on the range of the air-fuel ratio control signal. That is, if it is determined in step 320 that the range is within the range ■, the process proceeds to step 340;
If it is determined that the range is within the range ■, the process proceeds to step 350, and if it is determined that the range is within the range ■, the process proceeds to step 360. Similarly, if it is determined that the range is within the range ■ at step 330, the process proceeds to step 370. If it is determined that the range is within the range ■, the process proceeds to step 380, and if it is determined that the range is within the range ■, the process proceeds to step 390. These steps 340 to 360 and steps 370 to 390 are performed by the integrating circuit 2.
8, and in steps 340 to 360, the reference voltage VL is set to a voltage value ΔV1. The value VL + ΔVI (which is the sum of ΔVff and ΔV■
Step 340), VL+ΔVII (Step 350)
, Vl-10Δ■■ (step 360) is output as an integral output, and a duty ratio signal for multiplying by 1q is output. On the other hand, in steps 370 to 390, a duty ratio signal obtained by adding the voltage values ΔVI (step 370), ΔVII (step 380), and ΔVI[[(step 390) similar to those described above to the reference voltage VR is output.

FIG. 7 shows an example of the output of the monitor output terminal 22 obtained in this manner. In the figure, <a> is the oxygen sensor output, and (b) is the air-fuel ratio control signal, which are the same as (a) and (b) in FIG. 4 above. Figure 7 (
C) is the monitor output, and as shown in the figure, the oxygen sensor 10
Whether the output is rRJ or rLJ is easily determined by whether the voltage is lower or higher than the reference voltage VR, and the air-fuel ratio control signal is determined depending on how much higher the voltage value is than the reference voltages VL and VR at that time. Determination of the range can also be made easier. Therefore, in this embodiment, as in the above-described embodiments, two types of information can be observed through a single output terminal, and the operational status of the air-fuel ratio control signal can be easily grasped.

Further, its configuration is similar to the first embodiment, and requires only the addition and execution of a built-in algorithm program, allowing the use of microcomputers installed in current internal combustion engines.

In addition, in the above two embodiments, an example was explained in which the state of the air-fuel ratio control signal is roughly divided into three ranges and observed, but in order to observe the state of the air-fuel ratio control signal with higher accuracy, it is further divided into smaller ranges. Alternatively, it is clear that the two states of the output of the oxygen sensor 10 and the air-fuel ratio control signal can be easily observed as in the above embodiment even if the subdivision is further advanced and it is made almost analog. It is.

[Effects of the Invention] As described above with examples, the air-fuel ratio control device of the present invention has the following features: The air-fuel ratio control device of the present invention has the following features: In the air-fuel ratio control device that outputs an air-fuel ratio control signal to the internal combustion engine based on the above, the monitor output combines the output of the air-fuel ratio sensor and the air-fuel ratio control signal output to the internal combustion engine and outputs the result to the outside. It is characterized by comprising means and.

Therefore, by configuring a single output terminal and without requiring any switch operation, two pieces of information necessary for determining the operating status of the air-fuel ratio control device, namely the air-fuel ratio control signal and the air-fuel ratio control signal, can be obtained. This allows the fuel ratio sensor output signal to be observed. As a result, the operating status of the air-fuel ratio control device can be easily and accurately and quickly monitored, which has great effects.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a schematic configuration diagram of an internal combustion engine system equipped with an air-fuel ratio control device according to an embodiment,
Fig. 3 is a block diagram of the air-fuel ratio control device, Fig. 4 is an explanatory diagram of output waveforms of each part of the first embodiment, Fig. 5 is a flowchart of its control, and Fig. 6 is a control diagram of the second embodiment. The flowchart, FIG. 7, shows an explanatory diagram of the output waveforms of each part. 2...Engine 10...Oxygen sensor 20...Air-fuel ratio control device 22...Monitor output terminal

Claims (1)

[Scope of Claims] An air-fuel ratio control device that outputs an air-fuel ratio control signal to the internal combustion engine based on the output of an air-fuel ratio sensor that detects whether the air-fuel ratio of the internal combustion engine is higher or lower than a predetermined air-fuel ratio, comprising: An air-fuel ratio control device characterized by comprising a monitor output means for adding the output of an air-fuel ratio sensor and an air-fuel ratio control signal output to the internal combustion engine and outputting the result to the outside.