JPS6233092Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to an altitude compensation device in an air-fuel ratio control system. Generally, internal combustion engines that use a three-way catalyst are
In order to improve the purification efficiency of the catalyst, it is necessary to operate at a stoichiometric air-fuel ratio. To meet this requirement, conventionally, an exhaust gas sensor is used to detect the oxygen concentration in the exhaust gas of an internal combustion engine, and this detected value is compared with a set value to obtain a control signal, and feedback control is performed based on this. The air-fuel ratio of the supplied air-fuel mixture has been controlled to the stoichiometric air-fuel ratio. However, when considering the stability of the system and the capacity of the actuator, there is a tendency that the feedback control width in the feedback control system cannot be made sufficiently large. Furthermore, the responsiveness or feedback control width of this feedback control system is often adjusted assuming operation on flat ground, and if operation is performed at a high altitude with these adjustments in place. Since the air is becoming rarer, the necessary feedback amount may deviate from the control range, resulting in a phenomenon in which suitable operation at the stoichiometric air-fuel ratio cannot be performed. moreover,
Since the feedback signal is not generated until the exhaust gas sensor is warmed up, such as when starting an internal combustion engine, the internal combustion engine will naturally operate at the basic air-fuel ratio in flat ground conditions, and the actual supply The deviation between the air-fuel ratio of the air-fuel mixture and the stoichiometric air-fuel ratio becomes large, and the deviation becomes significantly larger as the operating altitude increases. As described above, with the conventionally known feedback control system, it has been impossible to properly maintain the supplied air-fuel mixture at the stoichiometric air-fuel ratio before the exhaust gas sensor is warmed up or when there is a change in altitude at the operating location. The purpose of the present invention is to provide a compensator and a compensator to maintain the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine at the stoichiometric air-fuel ratio without being affected by altitude fluctuations in the operating location of the internal combustion engine or the warm-up state of the exhaust gas sensor. In particular, deviations from the stoichiometric air-fuel ratio caused by altitude fluctuations in the operating location of the internal combustion engine are detected as deviations in the feedback control signal, and the feedback control system controls the air-fuel ratio in stages according to the magnitude of the detected deviations. The object of the present invention is to provide a device for compensating the amount. The gist of the present invention is an altitude compensation device applied to a control system that detects an exhaust gas component, preferably oxygen content, compares it with a set value, obtains an error signal, and performs feedback control of the air-fuel ratio based on the error signal. The purpose of the present invention is to obtain a deviation signal by comparing the average value of the error signal, which varies with time, with a set value, and to compensate for air-fuel ratio feedback control based on this deviation signal. Hereinafter, the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a schematic block circuit diagram showing one embodiment of the present invention. In the figure, numeral 1 indicates a conventionally known air-fuel ratio feedback control system. An exhaust sensor, preferably an oxygen sensor 2, for detecting the concentration of exhaust gas components is provided at a suitable location in an exhaust passage of an internal combustion engine (not shown). The first comparator 3 compares the electrical output signal S1 of the oxygen sensor 2 indicating the oxygen concentration in the exhaust gas with a preset reference oxygen concentration signal S2 and outputs a deviation signal S3. This deviation signal S3 is added to the adder 5, while the integrator 4
added to. The signal output S4 from this integrator 4 is also added to the adder 5 in the same way. The signals S3 and S4 are added by an adder 5 and outputted as an error signal (V _F ) S5, which is used to perform air-fuel ratio feedback control of the internal combustion engine in a conventionally known manner. In addition, in this embodiment, the feedback control system 1
Although proportional-integral operation is performed in , the present invention is not particularly limited to this. As mentioned above, the present invention detects altitude fluctuations at the operating location of the internal combustion engine based on the fact that the average value of the feedback signal within a predetermined time is outside the reference range, and is configured by branching out from the conventionally known control system. The compensation loop is operated to correct the air-fuel ratio compensation feedback signal due to the altitude change. Next, a compensation loop, which is the main component of the present invention, will be explained according to a preferred embodiment. The error signal average value calculator 6 calculates the average value (V _F ) of the error signal (V _F ) S5 since the start of the internal combustion engine operation, and outputs the average value signal S6 to the second comparator 7 . A reference signal generator 70 connected to a constant voltage source, for example, a battery power supply, generates an installation upper limit value (H) signal S7.
and installation lower limit value (L) signal S8 are applied to the second comparator 7. This second comparator 7 outputs a carry-in signal and an up-down signal to an up-down counter 8. The output S9 of the second comparator 7 depends on the magnitude of the average value signal S6 and both setting signals S7 and S8, and is determined, for example, as shown in the table below.

[Table] However, the input/output relationship in the above table is for when feedback control is ON according to the feedback ON/OFF switching circuit described later, and when feedback control is OFF, the above-mentioned second comparison Regardless of the input conditions to the comparator 7, the carry-in signal is 1 and any up-down signal is output from the comparator 7. The up-down counter 8 receives an output S9 from the second comparator 7, and also receives a pulse signal S10 output from the pulse generator 9 at a predetermined interval and a predetermined pulse width. Then, this pulse signal S10 is counted according to the truth table shown below.

[Table] As described above, the up-down counter 8 counts up or counts down the pulse signal S10 input during counting, latches the count number, and outputs it as a digital output signal S11. If there is no pulse input, the latched count number is output. In this way, when the change in the operating condition of the internal combustion engine increases beyond a certain level, the basic parameters are changed. On the other hand, as shown in the figure, only the drive power supply 90 of the up-down counter 8 is always ON, including when the key is OFF.
The memory is maintained even when the internal combustion engine is stopped. As a result, operation can be started in the optimum state even when the exhaust gas sensor is still inactive, such as during a cold start, and control can be effectively performed in a cold state (when feedback is OFF), such as 11 mode or LA#4 mode. As mentioned above, depending on the warm-up state of the oxygen sensor 2, it may not be possible to obtain an effective signal and there is a risk of erroneous evaluation, so this embodiment adopts the following configuration as a countermeasure. . Warm-up state check signal S indicating the warm-up state of oxygen sensor 2
20 from the first comparator 3.
In addition to the monitoring device 80 having an OFF switching circuit, the feedback control is turned ON or OFF. That is, if the oxygen sensor 2 is not warmed up properly, the feedback control is turned off and the up-down counter 8 is not counted. As the feedback OFF signal, an integration stop signal S21 that stops the operation of the integrator 4 as shown in the figure may be added, or the output signal S of the second comparator 7 may be added.
Signal S22 for making 9 a no-count code
It is preferable to add Alternatively, this may be done by making the up-down counter 8 inactive or stopping the generation of clock pulses. In this way, the up-down counter 8 performs counting only when the feedback control is ON. The latched digital output signal S11 of the up-down counter 8 is decoded by a decoder 10 and sent to the amplifier 2 according to a predetermined correspondence relationship.
It becomes an input signal to an arbitrary number of predetermined amplifiers among 1, 22, . . . , 2n. No signal is provided to the remaining amplifiers. Reference numeral 30 designates part of the carburetor air bleed of the internal combustion engine. According to the present invention, the amount of fuel supply and/or air supply can be controlled using the digital output signal S11, but in this embodiment, the amount of carburetor air bleed is controlled. Reference numeral 31 is an air cleaner (not shown)
32 indicates the carburetor (not shown) side. This carburetor air bleed system 30 has an appropriate number of branch paths 41, 42,...
..., 4n, each of which is provided with a solenoid valve 51, 52, ..., 5n for opening and closing the branch path. The solenoid valves 51, 52, . . . , 5n are electrically connected to the amplifiers 21, 22, . . . , 2n, respectively. The digital output signal S11 and the solenoid valves 51, 5
2, .

[Table] In this embodiment, the error signal average value calculation unit 6 corresponds to the air-fuel ratio corresponding value calculation means described in the claims of the utility model registration, and the second comparator 7 and the reference signal generator 70 correspond to The up-down counter 8, the pulse generator and the drive power supply 90 correspond to the storage means. As described above, according to the present invention, feedback is possible over a wider range than the conventional air-fuel ratio feedback control system, and since the count number is latched in the memory of the up-down counter, it is possible to control the air-fuel ratio during a cold start, that is, when the oxygen sensor is inactive. It is operated under proper conditions at all times, and the basic air-fuel ratio does not deviate significantly at any altitude.In addition, it has a function that compensates for differences in fuel properties or changes over time in the system, regardless of whether feedback is ON or OFF. This is extremely useful.

[Brief explanation of drawings]

The figure is a schematic block diagram showing an embodiment of the invention. 1... Air-fuel ratio feedback control system, 2... Oxygen sensor, 6... Error signal average value calculator, 7...
...Second comparator, 8...Up-down counter,
9...Pulse generator, 10...Decoder, 30...
...Carburetor air bleed system, 41, 42,...
..., 4n...branch route, 51, 52,..., 5n
……solenoid valve.

Claims (1)

[Claims for Utility Model Registration] 1. An exhaust gas sensor that detects the concentration of exhaust gas components of an internal combustion engine, an error signal generating means that generates an error signal by comparing the output value of the exhaust gas sensor with a reference value, and at least the exhaust gas a monitoring means that responds to the warm-up state of the sensor and determines whether or not the first air-fuel ratio control is possible based on the output value of the exhaust gas sensor; and feedback control of the air-fuel ratio of the internal combustion engine using a feedback value based on the error signal. an altitude compensator in an air-fuel ratio control system including a first air-fuel ratio control device, the air-fuel ratio corresponding calculation calculating an air-fuel ratio corresponding value of the internal combustion engine from an average value of the feedback control value based on the output value of the exhaust gas sensor; a comparison means for determining whether the result obtained by the air-fuel ratio corresponding value calculation means is within a predetermined range; and a second air-fuel ratio for adjusting the air-fuel ratio according to the comparison result of the comparison means. a storage means for updating and storing the control amount of the fuel ratio control device, and configured such that updating of the control amount in the storage means can be executed by the monitoring means only when feedback control is being performed by the first air-fuel ratio control device; . An altitude compensating device in an air-fuel ratio control system, wherein the memory in the storage means is retained even when the engine is stopped, and the air-fuel ratio is controlled by the first and second air-fuel ratio control means.