JPH03185238A - Fuel controller of engine - Google Patents

Abstract

PURPOSE:To eliminate any increase in excessive fuel by making control for decreasing fuel quantity of increase compensation as the humidity of intake air is high, when basic injection quantity of the fuel is increasingly compensated under a high load operation state of an engine. CONSTITUTION:An injector 7 is controlled by a controller 6 based on respective detected signals from various sensors 1-4 which detectes an operation condition of an engine so as to inject and supply a proper quantity of fuel to a combustion chamber. Then, the controller 6, seeks for basic injection quantity of fuel which is suitable for the operation condition of the engine where an air-fuel ratio of mixed air is set at a target value, and the fuel injection quantity is increased or decreased so that a detected value of the air-fuel ratio can approach the target value, and also proper compensation quantity is added to the basic injection quantity during a specified high load operation condition. With respect to the above constitution, in the controller 6, the fuel quantity of the above compensation is controlled to be smaller as the humidity of the intake air detected by a humidity sensor 5 is higher.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronically controlled engine, and more particularly to an engine fuel control device that adjusts the amount of fuel injected into the engine by an injector according to the engine condition.

(Prior Art) As disclosed in, for example, Japanese Unexamined Patent Publication No. 53-8427, the following fuel control technology has been conventionally employed in electronically controlled engines.

As is well known, an engine is equipped with various sensors and status switches such as an intake air amount sensor, rotational speed sensor, cooling water temperature sensor, air-fuel ratio sensor, and throttle position sensor, and a controller using a microcomputer. receives engine status information from these sensors and appropriately controls the amount of fuel injected into the engine from the injector.

The basic control is to find a basic injection amount (determined from the intake air amount and engine speed) that matches the engine condition so that the air-fuel ratio of the intake air-fuel mixture reaches the target value. When the engine speed and load parameters are within a predetermined zone, injection control is executed according to the basic injection amount, and the injection amount is fed back so that the detected value of the air-fuel ratio sensor approaches the air-fuel ratio target value. (This is referred to as air-fuel ratio feedback control means).

Furthermore, when the engine speed and load parameters are within a predetermined high load zone, fuel is injected in an amount equal to the basic injection amount plus an appropriate correction amount (
This is called the high load correction means). Note that when the feedback zone in which the air-fuel ratio feedback control means is operating changes to the high load zone, the fuel increase control by the high load correction means is executed after a certain delay time.

When the high load correction means described above functions, more fuel than the basic injection amount is supplied, and the air-fuel ratio becomes slightly richer than the target value. This increased amount of fuel acts to suppress the combustion temperature within the engine, thereby preventing overheating during high loads. However, the fuel consumption rate will worsen.

(Problem to be Solved by the Invention) The present inventors have closely observed how the combustion state inside the engine changes depending on the humidity of the air taken into the engine. As a result, the higher the humidity of the intake air, the lower the combustion temperature. (assuming other conditions remain the same, of course). This means that the higher the humidity of the intake air, the less likely overheating will occur during high loads.

In conventional devices, the humidity of the intake air is not a parameter that determines the fuel injection amount; the amount increased by the high load correction means is determined using parameters such as the size of the engine load and the cooling water temperature. It has nothing to do with the humidity. Therefore, even though the humidity of the intake air is high and overheating is unlikely to occur, the high load correction means increases the amount of fuel by the same amount as when the air is dry, so the disadvantage of worsening fuel consumption rate is noticeable. become.

This invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a fuel control device for an engine that prevents the increase in fuel amount by the high load correction means from becoming excessive (wasteful). .

(Means for Solving the Problems) Therefore, in the present invention, the temperature of the intake air is one of the control parameters in the high load correction means, and the higher the humidity, the smaller the amount of fuel increase due to the high load correction. did.

(Function) 1. The higher the humidity of human air, the smaller the amount of fuel increased by the high load correction means, but the effect of keeping the combustion temperature low is compensated for by the large amount of moisture in the intake air.

(Embodiment) FIG. 3 shows a schematic configuration of a fuel control device according to an embodiment of the present invention. Intake air amount sensor 1, rotation speed sensor 2
, water temperature sensor 3, air-fuel ratio sensor 4, humidity sensor 5, etc.
Sensors and switches are attached to the engine to collect various status information related to engine operation. A controller 6 consisting of a microcomputer takes in this engine state information and adjusts the amount of fuel injected into the engine by the injector 7 according to the engine state. Note that the humidity sensor 5 is for detecting the humidity in the air taken into the engine, and is a characteristic component of the device of the present invention.

FIG. 1 shows the main points of the fuel control process executed by the controller 6.

In the first step 101, various engine status information is taken in from the aforementioned sensors and switches. In the next step 102, a basic injection amount A that will cause the air-fuel ratio of the intake air-fuel mixture to reach a target value is determined by a table lookup method or the like using the engine speed and intake air amount as main parameters. In the next step 103, it is determined whether the engine condition is in a predetermined high load zone or in the feedback zone. If it is in the feedback zone, the process proceeds to the next step 104, where the air-fuel ratio feedback control executes injection control according to the basic injection mA and adds the injection amount so that the detected value of the air-fuel ratio sensor 4 approaches the air-fuel ratio target value. Run the first step 1
Return to 01.

When the engine state changes from the feedback zone to the high load zone, the determination in step 103 is YES, the determination in step 111 is NO, and the process proceeds to step 112. In step 112, a map of the characteristics shown in FIG. 2(A) set on the memory of the controller 6 is drawn, a delay time Td corresponding to the humidity of the intake air is drawn, and the time T
Preset d into a timer and start the timer. As shown in FIG. 2(A), the delay time Td increases as the humidity of the intake air increases.

In the next step 113, it is determined whether or not the timer for the delay time Td has timed up, and the air-fuel ratio feedback control in step 104 is executed until the timer has timed up. If the timer times up after the time Td has elapsed since the state changed from the feed pack zone to the high load zone, the process proceeds to step 114 and high load correction control is executed.

In step 114, a map of the characteristics shown in FIG. 2(B) is drawn to determine a high load increase coefficient a corresponding to the engine speed and intake air amount. At the same time, draw a map of the characteristics shown in Figure 2 (C) and derive the water temperature correction coefficient corresponding to the engine cooling water temperature (the coefficient is 1 at around 50°C).
(closest to , and becomes larger on the low and high temperature sides). In particular, a map of the characteristics shown in FIG. 2(D) is drawn to determine the humidity correction coefficient C corresponding to the humidity of the intake air.

(D) As shown in the figure, the higher the humidity, the higher the humidity correction coefficient C becomes 1.
gradually become smaller.

In the next step 115, it is determined whether the engine cooling water temperature is 30°C or higher, and if it is 30°C or higher, the process proceeds to step 121, where the basic injection fIA, the high load increase coefficient a, the water temperature correction coefficient, and the humidity correction coefficient C are calculated. The multiplied value is set as the fuel injection amount, and fuel is injected from the injector 7 accordingly.

In other words, the injection amount increases by A (aXbXc-1) with respect to the basic injection amount A. The increase in the injection amount becomes smaller as the humidity of the intake air becomes higher. This is the characteristic control of the present invention. Note that if the water temperature has not reached 30°C in step 115, the process proceeds to step 122, and fuel in an amount of AXaXb is injected. In this case, the humidity parameter is not included.

Note that the higher the humidity is, the longer the delay time Td set in the timer in step 112 is, so the higher the humidity is, the longer the time from entering the high load zone until the high load increase control is actually executed increases. This control also eliminates wasteful increase.

(Effects of the Invention) As explained in detail above, this invention focuses on the fact that when the humidity of intake air is high, the combustion temperature in the engine can be kept low, and when the humidity is high, high load correction is applied. Since the increase in fuel amount is made smaller, there is no excessive increase in fuel amount due to high load increase, and the fuel consumption rate improves.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an outline of a control procedure by an engine fuel control device according to an embodiment of the present invention, FIG. 2 is a conceptual diagram of a control map used in the process shown in FIG. 1, and FIG.
FIG. 1 is a block diagram showing a schematic configuration of an engine fuel control device according to an embodiment of the present invention. 5... Humidity sensor

Claims (1)

[Scope of Claims] A device that adjusts the amount of fuel injected into the engine by an injector according to the engine condition, the basic injection amount matching the engine condition so that the air-fuel ratio of the intake air-fuel mixture reaches a target value. means for determining the basic injection amount; air-fuel ratio feedback control means for executing injection control according to the basic injection amount and adjusting the injection amount so that the detected value of the air-fuel ratio sensor approaches the air-fuel ratio target value; and a high load correction means that injects fuel in an amount obtained by adding an appropriate correction amount to the basic injection amount when the fuel is in a load zone, wherein the high load correction means detects humidity of intake air. 1. A fuel control device for an engine, characterized in that the engine fuel control device is characterized in that it uses a detected value of a humidity sensor as one of the parameters, and that the higher the humidity, the smaller the amount of fuel for the correction.