JPS5827839A - Fuel supply device for internal combustion engine - Google Patents

Abstract

PURPOSE:To simplify the control of fuel supply by a method wherein the fuel supply is controlled in accordance with an output signal from a first and a second air flow rate detector of a specified type. CONSTITUTION:A heat ray type air flow rate detector 8 including a temperature dependent resistor is provided upstream a throttle valve 6 in an intake manifold 1 and another detector 9 of the same structure as the detector 8 is provided downstream of the valve 6, the outputs of which are inputted into an operation device 3 to control a fuel adjusting means 4. In this instance, the detector 8 is for detecting an air flow rate A and the detector 9 is for detecting the air flow rate A as well as a fuel flow rate F' of the fuel in the vaporized and atomized states. A difference F between the outputs A and F' repreasents an intake condition of a mixture at the detector 9 arranged position. Accordingly, if a relationship between the air-fuel ratio at a fuel supply part and that at the detector 9 position is determined preliminarily and experimentarily, it becomes possible to obtain a desired air-fuel ratio at the start of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an internal combustion engine for an automobile, which is equipped with a device for supplying fuel so as to maintain a predetermined air-fuel ratio in an intake pipe of the internal combustion engine, and an intake throttle device for a mixture of fuel and air. The present invention relates to a fuel supply device for use in a vehicle.

Conventionally, there has been a device of this type as shown in FIG. In FIG. 1, (1) is an intake pipe, (2) is an air flow rate detector, for example, an air flow rate detector based on the amount of displacement of an air flow or a blocking plate, and (3) is an air flow rate detector (
A calculation device that receives the output signal of 2) and calculates the fuel flow required to supply a mixture with a predetermined air-fuel ratio to the engine,
An electronic circuit consisting of a microcomputer, etc.

(4) is a fuel metering device for metering fuel in response to the output signal of the arithmetic device and supplying it to the fuel injector (5). (6) is an air-fuel mixture suction throttle device that is linked to an accelerator pedal (not shown), and (7) is an aperture dust detector that detects a change in the aperture of the throttle device and outputs it. The output signal of the aperture dust detector (7) is sent to the arithmetic unit (3) and serves as a fuel supply correction signal during acceleration etc. A cranking signal indicating .

Next, the operation of the apparatus shown in FIG. 1 will be explained. When the engine is started and in a normal operating state at a speed higher than the so-called idle speed, the air flow rate detector (2) first detects the amount of air taken into the intake pipe (1), and then the arithmetic unit (3) detects the amount of air taken into the intake pipe (1).
), the fuel amount F is calculated so that the air-fuel ratio becomes a predetermined air-fuel ratio, for example, 15 with respect to the air mA. An output signal corresponding to this fuel amount F is sent to the fuel injection device (4), and the fuel amount F is injected into the intake pipe (1) from the fuel injector (5). As described above, the air-fuel mixture having a predetermined air-fuel ratio is sucked into the internal combustion engine in an amount desired by the driver by the throttle valve device (6) linked to the accelerator pedal, and the engine is operated. By the way, during normal operation, that is, during operation other than when the engine suddenly changes in rotation or load, or when starting, an air-fuel mixture having a desired air-fuel ratio is sucked into the engine as described above. When there are sudden changes in conditions from outside the engine, the fuel injector (5)
Even though fuel is being supplied to maintain a predetermined air-fuel ratio, the air-fuel mixture taken into the engine may temporarily deviate significantly from the desired air-fuel ratio, causing problems in the first engine's operation. has been confirmed. For example, during sudden acceleration due to the opening of a throttle valve, the intake air-fuel mixture of the engine becomes too lean, causing a suffocating phenomenon due to misfires and the like.

In order to avoid such a problem, in the conventional device, the output signal of the throttle valve opening degree detector (7) is fed into the calculation device (3), and the calculation device (3) detects the temporal change in the throttle valve opening degree. Accordingly, an amount of fuel that is more or less than a predetermined amount of fuel determined for the air flow 'fiA is calculated, and more or less fuel is supplied from the injection device (5). Also, at the time of starting, it is necessary to supply a considerable amount of fuel in excess of the air flow rate A, and based on the input of the cranking signal, the calculation device (3) calculates the amount of excess fuel.
A rich mixture is sent into the intake pipe. In known electronically controlled fuel injection systems, such fuel supply methods are distinguished by the name of acceleration increase, deceleration decrease, and start increase, and special consideration is given to the normal fuel supply, and the above-mentioned method is used. As usual,
A configuration is adopted in which necessary parameters are added to the normal input parameters as needed to perform correction. Moreover,
In order to improve the accuracy of these corrections, it is necessary to add more input parameters, or to make complex calculations that involve classifying a relatively large number of conditions based on operational test data of internal combustion engines used together under various conditions. Currently, correction calculations are being performed.

The present invention has been made in view of the above-mentioned circumstances, and provides a fuel supply system for an internal combustion engine that supplies fuel using the same control method with relatively few input parameters for all operating states of the engine. is intended to provide.

An embodiment of the present invention will now be described with reference to the drawings. Second
In the figure, (8) is a known hot wire flow rate detector that is provided upstream of the intake pipe (1) and includes a temperature change dependent resistance. (9) is the hot wire flow rate detector (8
) - This is a flow rate detector with the same configuration as the fuel injection device, and is installed in the intake pipe on the downstream side of the fuel injection device.

The output signals of the flow rate detectors (8) and (9) are both sent to the arithmetic unit (
3) is input.

Next, the operation of the apparatus shown in FIG. 2 will be explained. A first flow rate detector (8) located upstream of the intake pipe detects the air flow rate A drawn into the intake pipe (1) according to the degree of opening of the throttle valve (6) linked to the accelerator. On the other hand, the second flow rate detector (9) located downstream of the throttle valve (6) detects the fuel injector (5).
) and detects the mixture flow rate of the fuel flow rate F discharged into the intake pipe (1) and the air flow tA.

The contents of the mixture flow rate detected here include the air flow rate A obtained by the first flow rate detector (8), and the fuel flow rate in the vaporized or atomized state of the discharged fuel F. Two components with a flow @F' corresponding to are detected.

By the way, when the operating conditions of the engine change within a relatively short period of time, such as when accelerating or decelerating, or when starting or starting, the transport mode of the air-fuel mixture in the intake pipe from the fuel supply section to the engine changes, i.e., the fuel is vaporized or misted. Two mixed modes of transport, fast inhalation transported with the air in the liquid state and slow inhalation due to viscosity with the air flow along the intake pipe wall in the liquid state, shift from the previous form of the fluctuation to a different form. Since this requires a finite equilibrium time (this equilibrium time varies depending on the shape and temperature of the intake pipe), the air-fuel mixture may temporarily differ from the air-fuel ratio of the air-fuel mixture generated in the fuel supply section. It has been experimentally confirmed that it can be inhaled into engines.

For example, when the throttle valve (6) goes from fully open to fully open in a short period of time due to sudden acceleration, the negative pressure inside the intake pipe (1) downstream of the throttle valve (6) will drop rapidly, causing the fuel vaporization rate to decrease. becomes smaller, the transport mode of the air-fuel mixture in the intake pipe changes to a slow fuel intake mode, and a lean air-fuel mixture is temporarily sucked into the engine.

From the above, it can be seen that the difference output F' between the output of the second flow rate detector (9) and the output of the first flow rate detector (8) provided in the air mixture flow downstream of the throttle valve (6) is By taking this, it is possible to know the intake form of the air-fuel mixture in the intake pipe at the position of the second flow rate detector (9).

Therefore, regarding the internal combustion engine and the intake system, for various intake air amounts A, the air-fuel ratio φ of the mixture in the fuel supply section and the intake pipe (1) where the second flow rate detector (9) is located are determined. , the air-fuel ratio Ao of the mixture supplied to one engine for a certain intake air flow rate is obtained experimentally in advance by determining "F'" when the tiles of the mixture taken into the engine match.
/)"o = If "F'" with respect to Ro is F'o, then in the embodiment of FIG. 2 according to the present invention, the difference output F between the output of the first flow rate detector and the output of the second flow rate detector is ' and F6 above
The arithmetic unit 1i (3)
Fuel is supplied by forming a feedback loop in which the supplied fuel flow mF is calculated and discharged. Therefore, the arithmetic unit (3) uses the desired air-fuel ratio for the air-fuel mixture supplied to the engine as a parameter, and calculates the above "F'" for the air flow rate A.
It is composed of a function generator that generates a signal, or a map-configured memory that can be accessed at high speed, a subtracter, a comparator, etc., and is actually composed of, for example, a microcomputer.

If fuel is supplied using the control method described above, even when the engine is started, for example, there is no need for a special input signal for detecting the start, and of course the result of the above control method is that there is no concept of increasing the starting amount. It is clear that for a certain intake air flow rate A, an increased fuel supply is made (because F' becomes very small) compared to the supplied fuel flow rate during normal operation of the warm scale. It is clear that during acceleration, fuel is supplied in a similar manner so that the air-fuel mixture has the desired air-fuel ratio.

As described above, according to the present invention, conventionally, the basic control is the control of fuel supply during normal operation, and at the time of startup, acceleration, etc., detection is performed in some form, and this detection is performed in some way. When the above basic control is detected, the same control method can be used consistently without performing special correction control such as so-called starting power increase and acceleration power increase, and the control method is simplified and the above special Since there is no need for a means for detecting specific operating conditions, the device as a whole can be made very inexpensive. In addition, the supplied fuel flow rate for a given intake air flow rate is controlled in a closed loop by the fuel supply section, a flow rate detector downstream of the supply section, and a calculation section using the fuel flow rate in the mixture at a certain point in the intake pipe as a variable. Therefore, there is also the effect that fuel can be supplied with good quality.

[Brief explanation of drawings]

Fig. 41 is a configuration diagram showing a conventional fuel supply device for an internal combustion engine;
FIG. 2 is a configuration diagram showing a fuel supply system for an internal combustion engine according to an embodiment of the present invention. In the figure, (11... intake pipe, (2)... air flow rate detector, (3)... calculation device, (4)... fuel metering device, (5)... fuel injection (6)... Throttle valve device, (7)... Throttle valve opening degree detector, (8) (9)... Hot wire flow rate detector. Note that the same reference numerals in each figure are the same. − or a corresponding portion. Agent Shin Kuzuno −

Claims (1)

[Claims] A fuel supply device and a mixture suction throttle device are provided in an intake pipe of an internal combustion engine, and a first flow rate detection device includes a temperature-dependent resistance upstream of the fuel supply device and the mixture suction throttle device. a second flow rate detector having the same configuration as the first flow rate detector on the downstream side, and output signals of the first flow rate detector and output signals of the second and first flow rate detectors. A fuel supply system for an internal combustion engine, characterized in that the fuel supply system supplies fuel so as to generate an air-fuel mixture having a predetermined air-fuel ratio.