JP2703259B2 - Engine fuel supply - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel supply device for an engine.

(Prior Art) Conventionally, as one of widely known fuel control devices for an engine, there is a device that determines a fuel supply amount based on an intake air amount detected by an air flow meter and an engine speed. Although the fuel supply control based on the intake air amount is performed, there is an advantage that more accurate control is possible.On the other hand, for example, when the throttle valve is suddenly opened, such as during a transitional period of an acceleration operation, the intake air amount increases rapidly. There is a problem in that the meter cannot follow completely, and an error occurs between the actual intake air amount and the intake air amount detected by the air flow meter, and as a result, fuel control accuracy deteriorates and acceleration responsiveness decreases. .

From this, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-32626, during an acceleration operation in which the throttle opening changes suddenly, the acceleration operation is increased by increasing the fuel in accordance with the throttle opening change rate. A technique has been proposed to secure the acceleration response in a period.

However, in this known example, since the fuel increase correction in the transient period of the acceleration operation is a so-called expected correction that is performed by designating the correction amount from the throttle opening change rate to the last, the fuel control accuracy is improved. There was a limit naturally.

Further, as a method for coping with such a problem of each conventional fuel supply device, high fuel control accuracy is achieved by performing fuel supply control based on an intake air amount, that is, an output value of an air flow meter and an engine speed. A first fuel supply control system that can be obtained, and a second fuel supply control that can obtain a highly responsive fuel control by performing the fuel supply control based on the throttle opening and the engine speed. Two fuel supply control systems are provided, and the fuel supply control system is switched from the first fuel supply control system to the second fuel supply control system when the throttle opening change rate is equal to or more than a predetermined set value. Things are also known.

However, in this method, since the reference throttle opening change rate, which is the switching reference of the fuel supply control system, is fixedly set to a constant value, the following problem may occur.

That is, when the reference throttle opening change rate is set on the high throttle opening change rate side, the operating range of the fuel supply control system based on the air flow meter output value is large, and when viewed as a whole, the fuel control accuracy is high. It can be said that this is a control system that places importance on. However, in this case, when the fuel supply device based on the output value of the air flow meter is performed during cold time when the vaporization / atomization of the fuel is poor, it is assumed that the fuel supply amount is performed with high accuracy in order to obtain a predetermined air-fuel ratio. However, there is also a problem that the intake fuel amount of the engine is not immediately reflected (that is, a delay in fuel supply), and as a result, the acceleration response is reduced.

On the other hand, when the reference throttle opening change rate is set to the low throttle opening change rate side, the operation area of the fuel supply control system based on the throttle opening is large, and responsiveness is emphasized when viewed as a whole. It can be said that it is a control system. However,
In this case, even when the fuel supply control based on the output value of the air flow meter provides sufficient responsiveness, the throttle opening degree is maintained even when the fuel is sufficiently vaporized and atomized during the warm period. The fuel supply control based on the control is frequently performed, and the fuel control accuracy is reduced accordingly.

(Object of the Invention) In view of such a conventional problem, the present invention provides an engine fuel supply apparatus having a fuel supply control system based on an intake air amount and a fuel supply control system based on a throttle opening. The purpose of the present invention is to make it possible to achieve both fuel control accuracy and acceleration response regardless of the height of the vehicle.

(Means for Achieving the Object) In the present invention, as means for achieving the above object,
A first fuel supply control system for performing fuel supply control based on the intake air amount, a second fuel supply control system for performing fuel supply control based on the throttle opening, and the first fuel supply control system A reference throttle opening change rate, which is a reference for switching the second fuel supply control system, is set to a predetermined throttle opening change rate in a direction in which the throttle opening increases,
A reference throttle opening change rate setting means for setting the reference throttle opening change rate in accordance with the engine temperature so as to be smaller as the engine temperature is lower, and a throttle opening change rate in an increasing direction of the throttle opening. When the fuel supply control system is in a small low throttle opening change rate range with respect to the reference throttle opening change rate, the fuel supply control system is the first fuel supply control system, and when the fuel supply control system is in a large high throttle opening change rate region, Switching timing control means for setting the fuel supply control system to the second fuel supply control system.

(Operation) In the present invention, the reference throttle opening change rate, which is the switching reference of the fuel supply control system, is set to a predetermined value in the increasing direction of the throttle opening, and corresponds to the engine temperature. When the throttle opening change rate in the increasing direction of the throttle opening is in a low throttle opening change rate range smaller than the reference throttle opening change rate, the fuel supply is performed. When the control system is the first fuel supply control system based on the intake air amount, and the throttle opening change rate is in a high throttle opening change rate range that is larger than the reference throttle opening change rate, the fuel supply control system Is the second fuel supply control system based on the throttle opening, so when the engine is cold (that is, when the reference throttle opening change rate is small). Fuel supply control based on the throttle opening with good response is performed from the throttle card change rate range. When the engine is warm (that is, when the reference throttle change rate is large), the fuel supply control is performed up to the high throttle change rate range. The fuel supply control based on the intake air amount with high fuel control accuracy is performed.

(Effect of the Invention) Therefore, according to the fuel supply device for an engine of the present invention,
The fuel supply control based on the throttle opening with good responsiveness is performed in a wide range when the engine is cold. Fuel vaporization and
Fuel control based on the intake air amount is performed over a wide range during warm engine conditions where atomization is good and fuel supply delay is almost non-existent. The effect of achieving both the accuracy and the acceleration response can be obtained.

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG. 1 to FIG.

FIG. 1 shows a four-cylinder engine 1 for an automobile equipped with a fuel supply device according to a first embodiment of the present invention. In FIG. 1, reference numeral 2 denotes an intake passage, and reference numeral 3 denotes an exhaust passage. A throttle opening sensor 6 and an air flow meter 7 are mounted on the upstream side of the intake passage 2 respectively. Also,
Four independent intake passages 4, 4 which are located downstream of the intake passage 2 and which are independently maintained for the respective cylinders of the engine 1.
. Are provided with injectors 5 respectively.

Further, in FIG.
Is a water temperature sensor for detecting the temperature of the cooling water of the engine 1 (that is, the engine temperature), and 10 is a control unit for controlling fuel supply. The control unit 10 includes an engine speed signal A ₁ corresponding to the engine speed from the distributor 8, a water temperature signal A ₂ corresponding to the engine temperature from the water temperature sensor 9, a throttle opening sensor throttle opening degree signal a ₃ corresponds to 6 to the throttle opening degree, also the intake air signal a ₄ corresponding to the intake air amount from the air flow meter 7 are input. And this control unit 10
In the fuel supply quantity (injection pulse width) is calculated on the basis of these signals, and outputs an injector drive signal A ₅ each injector 5,5 ....

Hereinafter, fuel supply control by the control unit 10 will be described in detail with reference to FIG.

The fuel supply device of this embodiment has two control regions, a region I and a region II, as shown in FIG. Among these two control regions, a region I is a control region by a first fuel supply control system for obtaining a fuel supply amount from an air flow meter output value and an engine speed, and can perform highly accurate fuel control. You. The basic injection pulse width Tp in this region I is obtained by Tp = K · Q / N (K: coefficient, Q: intake air amount, N: engine speed).

On the other hand, the area II is a control area by the second fuel supply control system in which the fuel supply amount is obtained from the throttle opening and the engine speed, and a highly responsive fuel control can be obtained. In this embodiment, a basic injection pulse width Tp in this region II is a predetermined equal injection pulse width line based on the engine speed (N) and the throttle opening (TVO) as shown in FIG. (11 _{1 to} 11 ₆ ). In this case, each equal injection pulse width line (11
Basic injection pulse width Tp represented by ₁ to 11 _6), as those corresponding to the low speed side of the engine (as curve 11 ₁ side) is set so that its value increases. For example, if the throttle opening is the same, the intake pressure at the downstream of the air flow meter is lower than at low speeds because the intake negative pressure of the engine is large at high speeds, and the intake filling efficiency decreases accordingly. To reduce the basic injection pulse width Tp,
Conversely, at low speeds, the intake pressure downstream of the air flow meter is higher than at high speeds, and the intake charging efficiency is improved accordingly. Therefore, the basic injection pulse width Tp is correspondingly increased.

Next, the actual control will be described with reference to the flowcharts shown in FIGS. 2 and 3. First, the fuel supply control system is selected by the control routine of the fuel supply control system shown in FIG. That is, after the control starts, the current water temperature (TW)
Is read (step S ₁ ), and the reference throttle opening change rate ΔTA ′ is obtained from the map shown in FIG. 4 based on the water temperature (TW) (step S ₂ ). That is, for example, when the current water temperature is WTe as shown in FIG. 4, the reference throttle opening change rate serving as a switching reference of the fuel supply control system at this time is ΔTAe ′.

Then, read the current throttle opening TA ₁ and the previous throttle opening TA ₀ and respectively (Step S _3, S _4), a throttle opening change rate .DELTA.TA during this period .DELTA.TA = TA ₁ -T
Determined from formula of A ₀ (Step S _5). Then, the obtained current throttle opening change rate ΔTA is compared with the reference throttle opening change rate ΔTA ′ (step S ₆ ), and ΔTA ≧
Since in the case of .DELTA.TA 'hits the region II shown in FIG. 4, with in this case is ON sets the flag F ₁ indicating the start of control by the second fuel supply control system (step S _7),
The flag F ₂ indicating the control start by the first fuel supply control system
To OFF setting (step S _8).

On the other hand, if ΔTA <ΔTA ', the region I in FIG.
In this case, in contrast to the above case, the flag
The F ₂ was set to ON, the OFF setting the flag F ₁ (step S _9, S
₁₀ ).

Next, the basic injection pulse width Tp in each fuel supply control system is calculated according to the basic injection pulse width calculation routine shown in FIG. That is, first flag F ₁ is see if ON setting or OFF setting in the step P ₁ (i.e., to confirm the current control region). Further the flag F ₂ when the flag F ₁ is set to ON
There whether ON setting, and when the flag F ₁ is OFF settings see whether the flag F ₂ is set to ON (step
P _2, P _6).

Then, the flag F ₁ may moreover flag F ₂ is OFF setting is also OFF setting, and a flag F ₁ is the ON setting yet flag F ₂
Is ON, an error is determined, and the following calculation flow of the basic injection pulse width is not executed.

Flag F ₁ is OFF, when the flag F ₂ is ON, since the current control area definitely an area I, first current to the air flow meter output value in step P _3, also the current in step P ₄ Read the engine speed and calculate the basic injection pulse width Tp from these values (step
P _5).

In contrast, the flag F ₁ is ON, if the flag F ₂ is OFF, since the current control region is definitely region II, in this case, the current air flow meter output value in step P ₇ (Throttle opening) and step P ₈
Then, the current engine speed is read, and then the basic injection pulse width Tp is calculated from these values (step P ₉ ).

Thus outputting the injector driving signal A ₅ each injector 5,5 ... in accordance with the basic injection pulse width Tp corresponding to each control region which is determined.

FIG. 6 is a time chart showing the switching state of the fuel supply control system during the acceleration operation. In the first embodiment, as is apparent from the above flowchart, the first fuel supply control is performed when the throttle opening change rate ΔTA exceeds the reference throttle opening change rate (time t ₁ ). The control system is switched from the second fuel supply control system to the second fuel supply control system, and when the throttle opening change rate ΔTA falls below the basic throttle opening change rate (for example, time t ₂ ), the second fuel supply control system is again switched from the second fuel supply control system. The control is switched to the first fuel supply control system. In this case, during normal acceleration operation, the output value of the air flow meter also changes substantially following the change in the throttle opening, and the control system is reset when the throttle opening change rate falls below the reference throttle opening change rate. Even when returning from the second fuel supply control system to the first fuel supply control system, high-precision fuel control can be secured with almost no trouble. However, during an extremely rapid acceleration operation, the output value of the air flow meter may not be able to follow the change of the throttle opening degree. It is possible that you are in the process of changing. In this case, as shown in FIG. 6 as the second embodiment, the switching from the first fuel supply control system to the second fuel supply control system is performed in the same manner as in the first embodiment. The return switching from the second fuel supply control system to the first fuel supply control system is performed regardless of the throttle opening change rate. If the output value of the air flow meter is used as a reference and the output value is stabilized (time t ₃ ), highly accurate fuel control can be performed immediately after returning to the first fuel supply control system.

[Brief description of the drawings]

1 is a system diagram of an engine provided with a fuel supply device according to an embodiment of the present invention, FIGS. 2 and 3 are control flowcharts of the engine shown in FIG. 1, and FIG. 4 is a diagram of FIG. FIG. 5 is a correlation diagram between the engine speed and the throttle opening, and FIG. 6 is a time chart showing the correlation between the throttle opening and the air flow meter output when the fuel supply control is switched. It is a chart figure. DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Intake passage 3 ... Exhaust passage 4 ... Independent intake distribution passage 5 ... Injector 6 ... Throttle opening degree sensor 7 ... Air flow meter 8 ... Distributor 9 ... Water temperature sensor 10 ... Control unit

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-258143 (JP, A) JP-A-62-291444 (JP, A) JP-A-62-107248 (JP, A) 24336 (JP, U) JP-B-59-7017 (JP, B2)

Claims (1)

(57) [Claims] A first fuel supply control system for performing fuel supply control based on an intake air amount; a second fuel supply control system for performing fuel supply control based on a throttle opening; A reference throttle opening change rate, which is used as a reference for switching the second fuel supply control system from the supply control system, is set to a predetermined throttle opening change rate in a direction in which the throttle opening increases. A reference throttle opening change rate setting means for setting the change rate to correspond to the engine temperature so as to be smaller as the engine temperature is lower; and a reference throttle opening change rate in a direction in which the throttle opening increases in the increasing direction. When the change rate is in a small low throttle opening change rate range, the fuel supply control system is the first fuel supply control system, and the fuel supply control system is in a large high throttle opening change rate range. The fuel supply system for an engine, wherein a fuel supply control system provided with a switching time period control means to said second fuel supply control system.