JPH04252831A - Air-fuel ratio controller of engine - Google Patents

Abstract

PURPOSE:To prevent any increase in excessive fuel by setting a narrow fuel increase quantity correction range for a fuel correction coefficient map used for controlling an air-fuel ratio during constant operation. CONSTITUTION:A basic fuel injection quantity Tp is calculated in a circuit 3 from an intake quantity Qz and rotational speed Ne of an engine detected by sensors 1, 2, and a fuel correction coefficient KMR is set in setting device 4a, 4b from the basic fuel injection quantity and the engine rotational speed Ne based on a fuel correction coefficient map including a wide increase quantity correction range, and the fuel correction coefficient map including a narrow one. A changeover switch 6 responds to a speed change ratio Gp detected by a sensor 7, and a corrected coefficient from the setting device 4b is selected in the case of the speed change ratio on the high speed side, and a correction coefficient from the setting device 4a is selected in the case of the other side. The basic correction injection quantity Tp is corrected by the selected correction coefficient in a correction device 5 so as to determine the fuel injection quantity Ti. It is thus possible to prevent such an event as a quantity increasing direction is determined in the same way as the case of acceleration requirement with the speed change ratio on the high speed side where fuel consumption is considered significant.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling the air-fuel ratio of an engine.

2. Description of the Related Art As this device, there is one described in a technical manual regarding ECCS, which has been developed by the applicant of the present application and is currently in use.

This device, as shown in FIG. 6, includes a sensor 1 for detecting the engine intake air amount Qa and an engine rotation speed
A basic injection amount calculation circuit 3 receives signals from these sensors to determine the intake air amount Qa.
The basic fuel injection amount is calculated from the engine speed Ne and the engine rotation speed Ne, and the valve opening time Tp of the injector (fuel injection valve) corresponding to this injection amount is determined. This time (basic injection amount) Tp corresponds to the required load of the engine, and from this and the engine speed Ne, the correction coefficient setter 4 determines the fuel correction coefficient KMR based on the fuel correction coefficient map shown in FIG.

[0003] The corrector 5 adjusts the basic injection amount Tp by a coefficient KMR.
The fuel injection amount is calculated by correcting it, and the corresponding injector valve opening time Ti is calculated as Ti = (1+KMR) Tp
This is determined by the following. From this, KM in Figure 4
In the R=0 region, Ti = Tp, and in the increase correction region, the fuel injection amount Ti is increased to be larger than the basic injection amount Tp.

0004

[Problems to be Solved by the Invention] In the conventional air-fuel ratio control device, a correction coefficient KMR corresponding to the engine operating condition is determined based only on a specific fuel correction coefficient map, and thereby the fuel supply amount (air-fuel ratio ) caused the following problems. In other words, the solid line in Figure 7 is a redrawn version of the map in Figure 4 with throttle opening degree scaled on the vertical axis, but the throttle opening degree is increased to 3/4 degree while driving in low gear at point A1. Considering the case of accelerating from point A2 to point A3, the increase in throttle opening from point A1 to point A2 enters the increase region, the air-fuel ratio is enriched in response to the acceleration request, and the fuel correction coefficient map in Fig. 4 is It is a preferable map with so-called medium acceleration. As a result of the driver returning the throttle opening to enter steady driving after this acceleration, the transmission upshifts to the high speed gear ratio and reaches the A4 point. While increasing the throttle opening again and moving to point A5 along the equal horsepower line shown by the dashed-dotted line, we are not originally requesting acceleration and should be focusing on fuel efficiency, but the engine is increasing the amount of power. range, resulting in deterioration of fuel efficiency,
This results in an increase in unburned substances in the exhaust gas.

[0005] The present invention provides an air-fuel ratio control device that makes it possible to change the increase correction coefficient map, from the viewpoint that the above-mentioned problems will be reduced if the increase correction range is narrow as shown in FIG. With the goal.

[0006]

[Means for Solving the Problems] For this purpose, the present invention controls the air-fuel ratio by correcting the amount of fuel supplied to the engine based on a fuel correction coefficient map predetermined from the operating state of the engine. The apparatus includes a gear ratio detection means for detecting a gear ratio of a transmission that changes rotation from the engine, and a map with a narrow increase correction range as the predetermined map at a high speed gear ratio in response to a signal from the means. The fuel correction coefficient map changing means is configured to use a fuel correction coefficient map changing means.

[0007] The operating condition that causes the above-mentioned problem can be determined not only from the gear ratio, but also from the rate of change in the engine intake air amount and engine speed. Therefore, the present invention provides an apparatus that controls the air-fuel ratio by correcting the amount of fuel supplied to the engine based on a fuel correction coefficient map predetermined from the operating state of the engine. Intake air amount change rate detection means and rotation speed change rate detection means for detecting the rotation speed change rate, and responsive to signals from these means,
The present invention also proposes an air-fuel ratio control device comprising fuel correction coefficient map changing means that uses a map with a narrow increase correction range as the predetermined map while both rates of change are low.

[0008]

[Operation] When the gear ratio detected by the gear ratio detection means is a high-speed gear ratio, the fuel correction coefficient map changing means corrects the amount of fuel supplied to the engine based on the map with a narrow increase correction range to adjust the air-fuel ratio. Control. Therefore, when driving in which a high vehicle speed gear ratio is selected, that is, when driving where fuel efficiency is more important than acceleration, unnecessary increase corrections are suppressed and fuel efficiency is reduced and unburned substances in the exhaust are reduced. Increase in volume can be prevented.

The intake air amount change rate detection means and the rotational speed change rate detection means detect the intake air amount change rate and the rotational speed change rate of the engine, respectively. While both of these rates of change are low, the fuel correction coefficient map changing means corrects the amount of fuel supplied to the engine based on the map with a narrow increase correction range to control the air-fuel ratio. Therefore, during operation where both the rate of change in intake air volume and the rate of change in rotational speed of the engine are low, that is, during steady operation where fuel efficiency is more important than acceleration, unnecessary increase corrections are suppressed, resulting in worsening of fuel efficiency and unburned exhaust gas. It is possible to prevent an increase in the amount of substances.

0010

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the air-fuel ratio control device of the present invention.
In the figure, the same parts as in FIG. 6 are designated by the same reference numerals. In this example, the normal fuel correction coefficient map KMRM shown in FIG.
In addition to AP1, the above-mentioned figure 8 has a wider increase correction range.
A fuel correction coefficient map KMRMAP2 shown in FIG. 5 corresponding to the above is prepared. As shown in FIG. 1, in this example, two fuel correction coefficient setters 4a and 4b are provided, and the former is provided with the map KMR of FIG.
MAP1 is assigned, and the map KMRMAP2 in Figure 5 is assigned to the latter.
Assign. The setting devices 4a and 4b are the same as the setting device 4 in FIG. 6, except for the map assigned in this way, and the fuel correction coefficient KMR is calculated from the basic injection amount Tp and the engine number Ne based on the corresponding map. Set.

The fuel correction coefficients from both set values 4a and 4b are input to a changeover switch 6 as fuel correction coefficient map changing means. This switch responds to the gear position (gear ratio) Gp detected by the gear position sensor 7 as a gear ratio detecting means, and is set at the illustrated switching position while this is a high-speed gear ratio (for example, the highest speed). The fuel correction coefficient KMR from the setting device 4b is selected, and the fuel correction coefficient KMR from the setting device 4a is selected for other low speed gear ratios, and the selected KM
Assume that R is input to the corrector 5.

The operation of this example will be explained next. The circuit 3 determines the basic fuel injection amount (basic injector valve opening time) Tp from the engine intake air amount Qa and the engine rotational speed Ne detected by the sensors 1 and 2. The fuel correction coefficient setters 4a and 4b set the fuel correction coefficient from the above-mentioned Tp and engine rotational speed Ne based on the corresponding maps of FIGS. 4 and 5, respectively. The changeover switch 6 selects the fuel correction coefficient from the setting device 4b while the speed ratio detected by the sensor 7 is a high speed speed ratio, and selects the fuel correction coefficient from the setting device 4a while the speed ratio detected by the sensor 7 is a low speed speed ratio. A fuel correction coefficient is selected and input to the corrector 5. The corrector 5 calculates the fuel injection amount (injector opening time) T from this coefficient KMR and the basic fuel injection amount Tp.
i is determined by Ti = (1+KMR)Tp and commanded to the injector.

By the way, as described above, the fuel correction coefficient KMR is determined based on a map with a narrow increase correction range as shown in FIG. 5 for the high-speed gear ratio, and based on a map with a wide increase correction range as shown in FIG. 4 for other gear ratios. As a result, the following effects are achieved. That is, if the vertical axes in FIGS. 4 and 5 are replaced with the throttle opening, the results will be as shown in FIGS. 7 and 8. In these figures, when driving from point A1 to point A2 to A3, which is often done at medium and low speed gear ratios, the fuel correction coefficient KMR is calculated based on the map in Figure 7 (Figure 4) because of the medium and low speed gear ratios.
Since this is determined, it is possible to reliably increase the amount that matches the request and obtain the required acceleration force. on the other hand,
When driving from point A4 to point A5 along the equal horsepower line, which is often done at a high-speed gear ratio, the fuel correction coefficient KMR is determined based on the map in Figure 8 (Figure 5) because of the high-speed gear ratio. Therefore, wasteful increase in fuel consumption can be avoided and air-fuel ratio control that is suitable for fuel efficiency and exhaust purification that matches the requirements can be realized.

Incidentally, in the above example, the operation requiring a change in the fuel correction coefficient map is determined by changing the gear position (speed ratio).
It was determined based on Gp, but instead of this, the engine intake air amount Q
It can also be determined from the rate of change of a and the rotational speed Ne. FIG. 2 shows an embodiment based on this idea, which includes a differentiator 8 that differentiates the intake air amount Qa to find its rate of change αQa, and a differentiator 9 that differentiates the engine speed Ne to find its rate of change αNe. These differentiators 8 and 9 serve as intake air amount change rate detection means and rotational speed change rate detection means, respectively, and outputs αQa and αNe from these are sent to comparators 10 and 11, respectively.
a comparator 10 that compares with the set values αQas and αNes,
11 are αQa ≧αQas, αNe ≧αNe, respectively.
At time s, the output is set to H level, and by calculating the logical sum of these outputs, the OR gate 12 switches the changeover switch 6 from the position shown in the figure to the position shown by the dotted line.

In this example, αQa < αQas and αNe
<αNes, that is, when the changes in both the intake air amount Qa and the engine speed Ne are small, when driving steadily at a high speed gear ratio (for example, from point A4 in Figs. 7 and 8)
5 points), OR gate 1
2, the switch 6 can be placed in the solid line position to achieve the same purpose as in the example described above. Other than that (αQ
When a ≧αQas or αNe <αNes), the desired acceleration performance can be ensured by setting the switch 6 to the dotted line position.

In both FIGS. 1 and 2, when switching the fuel correction coefficient map, since the air-fuel ratio changes, the engine's optimum ignition timing and knocking limit ignition timing also change. It is preferable to change the ignition timing control map at the same time. FIG. 3 shows an application of this idea to the one in FIG. 1, in which a setter 13a to which the ignition timing control map ADV1 corresponding to the fuel correction coefficient map in FIG. 4 is assigned as an ignition timing setter, and a fuel correction coefficient map in FIG. A setter 13b to which the ignition timing control map ADV2 corresponding to the coefficient map is assigned is added, and a changeover switch 14 as ignition timing control map changing means is also added.

The setters 13a and 13b determine the ignition timing from the basic fuel injection amount (injector opening time) Tp and the engine speed Ne based on the assigned map. The changeover switch 14 indicates the gear position (speed ratio) G
p is in the position shown during the high-speed side gear ratio, and the setting device 13
The ignition timing from setter 13a is commanded to the ignition device 15 at other speed ratios. Therefore, when the fuel correction coefficient map of FIG. 4 is selected, the ignition timing control map ADV1 is selected, and when the fuel correction coefficient map of FIG. 5 is selected, the ignition timing control map ADV2 is selected. The ignition timing is controlled in accordance with the fuel ratio control, and the operating efficiency of the engine can be improved.

[0018]

As described in claim 1 or 2, the air-fuel ratio control device of the present invention operates in the increase correction region under a high speed gear ratio or when both the rate of change in intake air amount and the rate of change in engine speed are low. Since the configuration is configured to control the air-fuel ratio using a narrow fuel correction coefficient map, even though fuel efficiency is more important than acceleration performance at the time of driving, an increase in fuel consumption is easily performed, resulting in worsening of fuel efficiency or lack of exhaust gas. It is possible to prevent an increase in fuel substances from occurring. Furthermore, according to the structure of claim 2,
This is advantageous in that the existing intake air amount sensor and engine rotation sensor can be used as they are, and no additional sensors are required.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the air-fuel ratio control device of the present invention.

FIG. 2 is a system diagram showing another example of the present invention.

FIG. 3 is a system diagram showing still another example of the present invention.

FIG. 4 is a diagram of a fuel correction coefficient map.

FIG. 5 is a diagram showing another fuel correction coefficient map.

FIG. 6 is a system diagram showing a conventional air-fuel ratio control device.

FIG. 7 is an equivalent line diagram of FIG. 4;

FIG. 8 is an equivalent line diagram of FIG. 5;

[Explanation of symbols]

1 Intake air amount sensor 2 Engine rotation sensor 3 Basic injection amount calculation circuit 4a Correction coefficient setter 4b Correction coefficient setter 5 Compensator 6 Changeover switch (fuel correction coefficient map changing means) 7
Gear position sensor (gear ratio detection means) 8 Differentiator (
Intake air amount change rate detection means) 9 Differentiator (rotational speed change rate detection means) 13a Ignition timing setter 13b Ignition timing setter 14 Changeover switch (Ignition timing control map change means) 15 Ignition device

Claims (2)

[Claims] Claim 1: In a device that controls the air-fuel ratio by correcting the amount of fuel supplied to the engine based on a fuel correction coefficient map predetermined from the operating state of the engine, a speed change that changes the speed of rotation from the engine. gear ratio detection means for detecting the gear ratio of the aircraft; and fuel correction coefficient map changing means that responds to a signal from the means and uses a map with a narrow increase correction range as the predetermined map for the high speed gear ratio. An air-fuel ratio control device for an engine, comprising: 2. In a device that controls the air-fuel ratio by correcting the amount of fuel supplied to the engine based on a fuel correction coefficient map predetermined from the operating state of the engine, an intake air amount change rate detection means and a revolution speed change rate detection means for detecting the number change rate, and a map with a narrow increase correction range as the predetermined map while both the change rates are low in response to signals from these means. 1. An air-fuel ratio control device for an engine, comprising: fuel correction coefficient map changing means using a fuel correction coefficient map changing means.