JPS6053769B2 - Mixing ratio control device for electronically controlled fuel injection engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mixture ratio control device for an electronically controlled fuel injection engine.

A conventional mixing ratio control device is JP-A-52-1514.
As shown in Fig. 21, there is a system in which the air-fuel ratio at engine speed is made richer when driving in an urban area than when driving outside the engine.

However, if urban driving is determined based on a constant engine speed and suction negative pressure in this way, when driving in urban areas with low load and many rotational fluctuations, the frequency of switching the mixture ratio increases, deteriorating drivability, and increasing the engine speed. There is a problem in that the fuel increase is canceled when the engine is under load, resulting in a lack of output. This invention was made by focusing on these conventional problems, and involves controlling the mixture ratio using an intake air amount detection signal from an air flow meter and a throttle valve opening signal from a throttle valve opening switch. This solves the above problems and reduces the shock caused by torque changes when changing the mixture ratio during steady driving, and also reduces the frequency of changing the mixture ratio itself, improving reliability, control accuracy, responsiveness, engine output, The purpose is to improve various performances such as drivability.

To this end, the present invention includes a throttle valve opening degree detector that detects the opening degree of a throttle valve provided in an intake passage, and an air amount comparison means that compares an intake air amount signal detected by an air flow meter with an air amount setting value. , a first increasing means for increasing the amount of fuel when the air amount is less than a set value in an urban driving area; and a first amount increasing means for canceling the increase by the first amount increasing means when the air amount is more than the set value and the throttle valve is less than the set opening degree. A release means and a second increase means for increasing the amount of fuel when the air amount is at least a set value and the throttle valve is in a high-load operating range at a set opening or more are provided, and the mixture ratio is changed in at least three operating ranges. This is what I did.

The present invention will be explained below based on the drawings.

FIG. 2 is a diagram showing an embodiment of the present invention. First, to explain the configuration, 1 is the throttle chamber, 2 is the intake manifold, 3 is the exhaust manifold, 4 is the EGR (exhaust gas recirculation) valve, 5 is the negative pressure advance control device, 6 is the distributor, and 7 is the throttle valve. , an electric signal (intake air amount signal) S1 of the intake air amount detected by an air flow meter 9 provided in the intake passage 8 upstream of the throttle valve 7, and a throttle valve opening switch 10 provided in the throttle valve 7. Throttle valve opening signal S2 detected in
, the ignition signal S3 detected from the negative terminal of the ignition coil (ignition column) 11, and the cooling water temperature signal detected by the water temperature sensor (not shown) and the intake air temperature sensor 9''
The detected intake temperature signal S4 is sent to the control unit 12, and the control unit 12 controls the fuel injected by the fuel injection valve (fuel injector) 13.

FIG. 3 shows an example of the control circuit of the control unit 12. Next, the operation will be explained based on this figure.

First, the ignition signal S3 of the ignition coil 11 is waveform-shaped by the engine rotation signal generation circuit 21 to become the engine rotation pulse signal P1.

This pulse signal P1 and the intake air amount signal S1 of the air flow meter 9 are input to a basic pulse generation circuit 22 that controls the fuel injection pulse width, and a basic pulse P2 is calculated.
The pulse P2 is input to the increase pulse generation circuit 23. The intake air amount signal S1 is also input to the air amount signal comparison and increase signal generation circuit 24, and the magnitude relationship between the intake air amount Q and the set air amount Q1 is determined.

Generally, the relationship between the actual intake air amount Q and the voltage V of the intake air amount signal S1 is as shown in FIG. 4, as the voltage V of the intake air amount signal S1 decreases as the intake air amount Q increases.

Therefore, when the intake air amount Q is less than the set value Q1 (for example, Q1 = 30 i/hour corresponding to a load of 50-1H), that is, when the intake air amount signal S1 becomes larger than the set voltage value ■1 ( For example, in the case of the operating region I in FIG. sent to. Increased pulse generation circuit 2
In 3, an increase pulse is generated from the input increase pulse width,
A composite pulse P3 obtained by combining the basic pulse P2 and the increased pulse is output to the output amplification circuit 26.

The composite pulse P3 is amplified through the output amplification circuit 26 to become an injection pulse P4, which is transmitted to the injection valve 13 and actuates it to enrich the mixture ratio (for example, the air-fuel ratio (A/F)).
13-15) (see Figure 6). Next, the intake air amount signal S
When the voltage No. 1 changes below the set value (for example, in the area of ■ in FIG. 5), the air amount signal comparison circuit 24 outputs an air amount increase release instruction signal.

This instruction signal is delayed through an increase canceling delay circuit 27 for delaying the canceling of the increase for a certain period of time (for example, 5 seconds to one second), and is turned into an increase cancel signal P5 by the increase cancel circuit 28. When this increase release signal P5 enters the first increase circuit 25,
The first increase circuit 25 stops its operation. Therefore, since the pulse width of the basic pulse P2 is directly transmitted to the injection valve 13 via the output amplification circuit 26, the mixture ratio becomes thin (for example, A/F=15 to 17) (see FIG. 6). The increase release delay circuit 27 is configured to activate or release the increase when the intake air amount increases in a short period of time, such as when the vehicle starts, and then decreases when the vehicle shifts to steady driving. Frequent alternation would impair drivability, so this was provided to prevent this and improve control stability.

On the other hand, the throttle valve opening switch 10 is set to the throttle valve opening (for example, 4
0 degree) or more, the throttle valve switch signal (throttle valve opening signal) S2 is input to the second increase circuit 29 and the increase release circuit 28.

As a result, the first increase circuit 25 stops operating, and the second increase circuit 29 operates, thereby increasing the amount of fuel that matches the engine required mixture ratio (for example, A/F = 11 to 14) in the high load range. It can be supplied independently (see the operating ranges ■ and ■ in Figure 5). That is, the second increase circuit 29 calculates the increase pulse width according to the opening degree of the throttle valve and outputs it to the increase pulse generation circuit 23. In addition, other control signals S, such as a cooling water temperature signal, are transmitted to the other increase circuit 3.
0 and the increase pulse width is calculated.

This increasing pulse width is determined by the increasing pulse generating circuit 23.
Alternatively, the increasing pulse width output from the second increasing circuit 25 or 29 is combined with the basic pulse width to determine the pulse width of the injection pulse P4 (see FIG. 7). Therefore, it becomes possible to respond in detail to the mixture ratio request according to the warm-up state of the engine. FIG. 5 is a mixture ratio characteristic diagram of the above embodiment. In the relatively low load region 1 until the constant air flow control curve A is reached, the increase pulse width is output from the first increase circuit 25. , resulting in a slightly richer basic mixture ratio.

Constant air flow control curve A and constant throttle valve opening (400) curve B
In the relatively medium load region (2) between 2 and 3, the first increasing circuit 25 stops operating, so the mixture ratio becomes leaner. In the high load ranges (1) and (2) surrounded by the constant throttle valve opening curve B and the full load curve C, where the throttle valve opening is above a certain level, the second increase circuit 29 operates, resulting in a rich output mixture ratio. Note that the solid line D is a curve showing the 10-mode emission operation region, and the solid line E is an R/L (road) running curve. Table 2 shows the mixing ratios of these operating regions 1 to 2. Comparing Table 2 with Table 1 showing the conventional characteristics,
Although the results are almost the same, it is possible to control the mixture ratio according to the intake air amount, as shown in the constant air amount control curve A in Figure 5, which reduces the shock of changing the mixture ratio when the vehicle is running steadily. This can be prevented and drivability is improved.

Furthermore, as a means for detecting the intake air amount, it is possible to use the intake air amount signal S1 of the air flow meter 9, which has already been used for basic pulse width calculation in conventional electronically controlled fuel injection engines, as the mixture ratio increase signal. This makes it possible to reduce the cost by not requiring new detection means, simplify the system, improve the reliability of the entire system, and improve control accuracy.

In addition, since the detection means does not use factors determined by vehicle specifications such as vehicle speed and engine rotation speed, tire diameter,
Another advantage is that it can be easily adapted to vehicles with different vehicle specifications such as final drive gear ratio.

Furthermore, in this embodiment, even if the set air amount is reached, the delay circuit 27 can suspend the release of the air amount increase for a certain period of time.
Even if the intake air amount exceeds a set value in a temporary acceleration state such as when starting, the increase can be maintained without being canceled, so good driving performance can be ensured.

FIG. 8 shows another embodiment of the control unit 12 of the invention.

In this embodiment, the basic pulse P2 obtained by the basic pulse generation circuit 22 is integrated per unit time by the basic pulse width integrating circuit 31, and this integrated value (a certain output voltage) is compared with a set value. This is to determine the amount of air.

This takes advantage of the fact that the integral value of the basic pulse per unit time is proportional to the amount of intake air, and the above integral value is compared with the set value in the integral value comparison and increase signal generation circuit 32. When the integral value is below the set value, the first increase circuit 2
5 operates to enrich the mixture ratio, and on the other hand, when the integral value is greater than the set value, the increase release delay circuit 27 and the increase release circuit 28 operate to cancel the increase in the amount of the first increase circuit 25 and make the mixture ratio leaner. It operates as follows. FIG. 9 shows a time chart of increase in amount using this basic pulse integration method. The rest of the configuration is substantially the same as that of the previous embodiment, so a description thereof will be omitted. 10th
The figure shows another embodiment of the invention.

This embodiment shows a case where not only mixture ratio control is performed using the intake air amount signal S1, but also ignition timing and EGR control are performed. Generally, when the mixture ratio is switched, the ignition timing and EGR amount required by the engine change before and after the switch, depending on fuel efficiency, output, exhaust engineering mission, etc.

In other words, it is generally advantageous in terms of fuel economy, output, and exhaust system to operate with a rich mixture ratio by advancing the ignition timing and increasing the amount of EGR, but when using a lean mixture ratio, the ignition timing is delayed and the amount of EGR is increased. It is necessary to reduce the Normally, the ignition timing and the EGR amount are each controlled by a negative pressure signal, and a method of controlling the negative pressure signal by changing the negative pressure value by diluting the negative pressure signal with the atmosphere is available. This example is
As shown in the figure, the ignition timing control negative pressure signal system passage 33 and EG
A solenoid valve 35 is provided at the confluence of the R control negative pressure signal system passage 34, and outputs a signal from the increase release delay circuit 27 that operates when the air amount exceeds the set amount, as shown by the broken line in FIGS. 3 to 8. The amplification circuit 36 amplifies the signal and drives the solenoid valve 35 to open it.

When the solenoid valve 35 opens, it is in communication with the atmosphere through the filter 37, and the throttle chamber 1
The negative pressure signal of the ignition timing control negative pressure signal system passage 33 that communicates the ignition timing control negative pressure (■C negative pressure) outlet hole 38 provided in the ignition timing control negative pressure (■C negative pressure) outlet 38 and the negative pressure advance control device 5 of the distributor 6, and the throttle An EGR control negative pressure signal system passage 3 that communicates between a ventilated negative pressure outlet hole 40 provided in the ventilated part 39 of the chamber 1 and a VVT valve (EGR correction valve) 41.
The negative pressure signal of 4 is diluted by the atmosphere. As a result, the absolute value of the negative pressure becomes smaller at the same time as the mixture ratio is switched, making it possible to delay the ignition timing and reduce EGR. The ignition timing and EGR characteristics obtained in this example are shown in Table 3 below. Note that regions 1 to 3 are operating regions corresponding to FIG. 5, similar to Table 2. However, in the above region (2), there is actually no negative pressure source for operating the negative pressure advance angle control device, so the angle is retarded.

Similarly, in the region (2), there is actually no negative pressure source for operating the EGR valve, so the EGR amount changes from small to zero. In this way, appropriate ignition timing and EGR control can be performed using the increase switching signal based on the intake air amount signal S1, and the control performance can be improved.

As explained above, according to this invention, the suction. A throttle valve opening degree detector installed in the air passage detects the opening of the throttle valve, an air amount comparison means that compares the intake air amount signal detected by the air flow meter with the air amount set value, and an air amount comparing means that compares the intake air amount signal detected by the air flow meter with the air amount set value. a first amount increasing means for increasing the amount of fuel when the amount of fuel is in an urban driving range of less than 100 degrees, and an amount increasing canceling means for canceling the amount increase by the first amount increasing means when the air amount is equal to or more than a set value and the throttle valve is less than the set opening degree;
a second increase means for increasing the amount of fuel when the air amount is at least a set value and the throttle valve is in a high-load operation region where the throttle valve opening is at least the set opening; By dividing the engine into three operating regions and changing the mixture ratio for each region, it is possible to control the mixture ratio with high precision to suit each operating region, thereby satisfying fuel efficiency, exhaust composition, and output performance. can be done.

In addition, since the mixture ratio switching point in the specified urban driving area (area 1) can be expanded to the high load side and high rotation side using the signal from the air flow meter, torque changes and shocks due to mixture ratio switching can be relatively reduced. It is hoped that this will significantly improve drivability by reducing switching frequency in urban driving areas. Furthermore, since the high-load operating range is detected by a throttle valve opening detector, the response speed is incomparably faster than that of an airflow meter signal, and therefore the fuel amount can be quickly increased to improve driveability and output performance. You can improve your skills. Note that the present invention is characterized by high versatility and low cost because it does not require a vehicle speed sensor or other vehicle speed detection means that must be adapted for each vehicle type depending on the transmission specifications of the vehicle. Also, the fuel increase signal in the present invention can be used to adjust the ignition timing and E.
It is also possible to improve the control accuracy or performance of the GR.

[Brief explanation of drawings]

FIG. 1 is a mixture ratio characteristic diagram of a conventional mixture ratio control device, FIG. 2 is a sectional view of a first embodiment of the present invention, and FIG. 3 is a circuit diagram of a control unit which is the main part of FIG. Fig. 4 is a correlation diagram between the intake air amount and the electrical signal of the air flow meter (intake air amount signal), Fig. 5 is a mixture ratio characteristic diagram of the embodiment shown in Fig. 2,
FIG. 6 is a diagram showing a time chart of increase in air amount determination method using an intake air amount signal, FIG. 7 is a diagram showing the configuration of an injection pulse, and FIG. 8 is a main part of a second embodiment of the present invention. FIG. 9 is a circuit diagram of a certain control unit, FIG. 9 is a diagram showing a time chart of increase in quantity using the basic pulse integration method, and FIG. 10 is a sectional view of a third embodiment of the present invention. 4... EGR valve, 5... Negative pressure advance control device, 6... Distributor, 7...
... Throttle valve, 9... Air flow meter, 10...
... Throttle valve opening switch, 11... Ignition coil, 12... Control unit,
13... Injection valve, 21... Engine rotation signal generation circuit, 22... Basic pulse generation circuit, 23...
...Increase pulse generation circuit, 24...Air amount signal comparison and increase signal generation circuit, 25...First increase circuit, 26...Output amplification circuit, 27...・・・
... Increase release delay circuit, 28... Increase release circuit, 29... Second increase circuit, 31... Basic pulse width integration circuit per unit time, 32... ... Integral value comparison and increase signal generation circuit, 33... Ignition timing control negative pressure signal system passage, 34... EGR control negative pressure signal system passage, 35... Solenoid vanohib, 36...Amplification circuit, 41...VV
T valve.

Claims (1)

[Claims] 1. A control unit that controls the fuel supply amount based on the intake air amount signal from the air flow meter and the engine rotation speed signal, and a fuel injection valve that injects fuel into the intake system based on the injection pulse from this control unit. In an electronically controlled fuel injection engine equipped with a throttle valve opening detector that detects the opening of a throttle valve provided in the intake passage and an air flow meter that compares the intake air amount signal detected by the air flow meter with the air amount set value. a first amount increasing means for increasing the amount of fuel when the air amount is less than the set value in a predetermined urban driving area; A fuel increase canceling means for canceling the fuel increase by the fuel increasing means, and a second fuel increasing means for increasing the amount of fuel when the air amount is equal to or higher than a set value and the throttle valve is in a predetermined high load operating range than the set opening degree are provided. 1. A mixture ratio control device for an electronically controlled fuel injection engine, characterized in that two operating ranges are defined and the mixture ratio in each operating range is changed.