JP2531063Y2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly, to a technique for improving fuel increase control in an acceleration operation state after a deceleration operation.

<Prior Art> Conventionally, as an electronically controlled fuel injection device for an internal combustion engine, there is the following one.

That is, the basic fuel injection amount Tp (= K × Q / N; K is a constant) is obtained from the intake air flow rate Q detected by the air flow meter and the engine speed N detected by the crank angle sensor and the like.
And an air-fuel ratio that is set based on various correction coefficients COEF according to the engine operating state such as the engine temperature and a signal corresponding to the oxygen concentration in the exhaust from an oxygen sensor provided in the exhaust passage. After calculating the feedback correction coefficient α and the correction amount Ts based on the battery voltage, the basic fuel injection amount Tp is calculated.
Is corrected by these to calculate the final fuel injection amount Ti (=
Tp × COEF × α + Ts).

Then, by outputting an injection pulse signal having a pulse width corresponding to the set fuel injection amount Ti to the electromagnetic fuel injection valve, a predetermined amount of fuel is injected and supplied to the engine (Japanese Patent Laid-Open No. 59-5978). No. 203828).

By the way, at the time of engine acceleration, an amount smaller than the engine required amount is supplied to the engine due to a delay in increasing the wall flow rate that does not correspond to a change in the engine load, a delay in detecting the intake air flow rate by the air flow meter, and a delay in calculating the fuel injection amount. Since the air-fuel ratio may be over-lean due to the supply, the air-fuel ratio is prevented from being over-lean by injecting the fuel after increasing the fuel injection amount during the steady operation (Japanese Patent Application No. 61-199135).

Specifically, the detection delay correction coefficient K ₁ , the wall flow correction correction coefficient K _2, and the calculation delay correction coefficient K ₃ corresponding to the throttle valve opening change rate Δθ, the basic fuel injection amount Tp, and the engine speed N, respectively, are previously determined. Based on these settings, an increase correction coefficient Q _INC {= 1 + (K ₁ + K ₃ ) × K ₂ } of the intake air flow rate Q is calculated, and the intake air detected by the air flow meter by the increase correction coefficient Q _INC Increase the flow rate Q and correct (Q ←
Q × Q _INC ), so that the basic fuel injection amount Tp is increased and corrected.

Here, the throttle valve opening change rate Δθ indicates whether the engine is in a rapid acceleration state or a gentle acceleration state,
Because This can be estimated detection delay of the intake air flow rate Q by the air flow meter, during rapid acceleration detection delay increases, i.e., greater detection delay correction factor K ₁ is set when a large throttle valve opening change rate Δθ It is like that.

Further, the basic fuel injection amount Tp representing the engine load represents a state of fuel flowing along the wall surface of the intake passage, that is, a so-called wall flow state. as wall flow correction correction factor K ₂ is set, an increase in load during acceleration, i.e., it is also available corresponding to an increase of the wall flow.

Further, as the engine speed N increases, the calculation delay increases (the crack angle from the generation of the calculation trigger to the end of the calculation increases). Therefore, the calculation delay correction coefficient K ₃ increases as the engine speed N increases. Is set.

<Problems to be solved by the invention> However, in the above-described conventional acceleration increase control,
Similar increase correction was performed regardless of whether fuel cut control (injection stop control) was performed during deceleration operation before acceleration operation.

The fuel cut control is, for example, to stop the fuel injection supply when the engine speed N is equal to or higher than a predetermined value while the throttle valve is fully closed (idle position). The state of the wall flow in the initial stage of acceleration differs depending on whether or not there is a wall flow. That is, in the acceleration from the deceleration operation in which the fuel cut control is not performed, the amount of the wall flow in the initial stage of the acceleration is larger than in the case where the fuel cut control is performed, but in the conventional increase control, the wall flow is indirectly controlled. The wall flow correction amount is determined by the basic fuel injection amount Tp to be represented, and the increase correction corresponding to the presence or absence of the fuel cut control, in other words, the actual wall flow amount has not been performed.

For this reason, in the acceleration from the deceleration operation without the fuel cut control in which the wall flow increases, the increase correction of the intake air flow rate Q based on the basic fuel injection amount Tp (engine load) becomes excessive, and the air-fuel ratio exceeds There was a risk of misfiring due to enrichment.

The present invention has been made in view of the above-described problem, and regulates the amount of increase correction according to the presence or absence of fuel supply stop control during deceleration operation before acceleration, thereby increasing the air-fuel ratio over-rich by the increase correction. The purpose is to be able to avoid.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, during the acceleration of the engine, the fuel increasing means for increasing the amount of fuel supplied to the engine increases as the engine load decreases. A deceleration fuel cut means for cutting the fuel supply to the engine in a predetermined deceleration operation state, and when re-acceleration from deceleration in a non-cut state by the deceleration fuel cut means, and when the engine load is equal to or less than a predetermined value. At one time, there is provided an increasing correction amount decreasing means for decreasing the increasing correction amount by the acceleration fuel increasing means.

<Operation> According to such a configuration, when shifting from deceleration to acceleration, fuel cut is not performed in the deceleration operation state, and if the engine load at that time is equal to or less than a predetermined value, The increased increase correction amount is reduced. On the other hand, when the fuel cut is performed during the deceleration operation before acceleration, and when the engine load exceeds a predetermined value even when the vehicle is re-accelerated from the non-cut state, the fuel is normally increased according to the engine load. Correction is performed.

That is, in the case where the fuel injection is performed and the deceleration operation is shifted from the deceleration operation in the state where the wall flow is large to the acceleration. Therefore, the amount of increase correction is suppressed by the amount of the wall flow, so that the air-fuel ratio can be prevented from being over-rich.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows the configuration of the electronically controlled fuel injection device according to the present invention.

In the figure, air is sucked into an internal combustion engine 1 through an air cleaner 2, an intake duct 3, a throttle chamber 4, and an intake manifold 5.

The intake duct 3 is provided with a hot-wire flow meter 6 for detecting an intake air flow rate Q, and outputs a voltage signal U _S corresponding to the intake air flow rate Q. The throttle chamber 4 is provided with a throttle valve 7 interlocked with an accelerator pedal (not shown), and controls the intake air flow rate Q. The throttle valve 7 is provided with a throttle opening sensor 8 for detecting the opening θ. The intake manifold 5 is provided with an electromagnetic fuel injection valve 9 for each cylinder, and a control unit incorporating a microcomputer described later.
The valve is driven to open by an injection pulse signal from the engine 11 and fuel is fed from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator to inject and supply the fuel into the intake manifold 5. Further, a water temperature sensor 12 for detecting a cooling water temperature Tw in a cooling jacket 13 of the engine is provided.

The control unit 11 counts a signal for each crank unit angle output from the crank angle sensor 10 in synchronization with the engine rotation for a certain period of time, or measures a cycle of the signal for each crank reference angle to thereby determine the engine rotation speed N. Is detected.

The control unit 11 calculates the fuel injection amount Ti based on the intake air flow rate Q, the throttle valve opening θ, the engine rotation speed N, and the cooling water temperature Tw detected as described above. In, the detection value of the intake air flow rate Q is increased and corrected based on a correction coefficient set in advance according to the engine load (represented by the basic fuel injection amount Tp), the engine speed N and the throttle valve opening change rate Δθ. Accordingly, the fuel injection amount Ti is set after being increased and corrected. Then, by outputting an injection pulse signal having a pulse width corresponding to the set fuel injection amount Ti to the fuel injection valve 9, the engine 1
Is supplied with a predetermined amount of fuel. In the predetermined deceleration operation state of the engine 1, the fuel injection is stopped (fuel cut).
By doing so, the fuel efficiency and exhaust properties are improved. Further, the acceleration increase correction based on the engine load is restricted according to the presence or absence of the fuel injection stop control during the deceleration operation before the acceleration operation.

That is, in the present embodiment, the control unit 11
Is also used as a fuel increasing means at acceleration, a deceleration fuel cutting means, and an increasing correction amount decreasing means.

Next, the fuel injection control by the control unit 11 will be described based on the flowchart of FIG.

In step (referred to as “S” in the figure, the same applies hereinafter) 1, the engine speed N, the throttle valve opening θ, the intake air flow rate Q, and the cooling water temperature Tw detected by the sensors are input.

In step 2, the throttle valve opening change rate Δθ (throttle valve opening per execution cycle of this routine) is determined based on the throttle valve opening θ input this time in step 1 and the previous detection value stored in the previous step 12. Degree change).

In step 3, it is determined whether or not the engine 1 is accelerating based on the throttle valve opening change rate Δθ calculated in step 2. That is, when the throttle valve opening change rate Δθ calculated in step 2 is a predetermined value or more on the open side,
Assuming that the engine 1 is in the accelerating operation state, the process proceeds to the next step 4, and when the engine 1 is not in the accelerating operation state, the process proceeds to step 11 to set the increase correction coefficient Q _INC of the intake air flow rate Q to 1.

In step 4, it is determined whether or not the current acceleration operation state is before the deceleration operation state and the fuel injection stop control (fuel cut) is performed in the deceleration operation state.
In the fuel injection stop control, for example, when the throttle valve 7 is fully closed (idle position) and the engine speed N is equal to or higher than a predetermined value (for example, the rotation speed is 2200 rpm or higher), the fuel injection supply is stopped. If the fuel injection stop control according before decelerating operation state of the has not been performed, compares the basic fuel injection amount Tp and a predetermined injection quantity Tp ₁ calculated at the previous step 12 proceeds to step 5.

Then, when the basic fuel injection amount Tp representing the engine load is smaller than the predetermined injection amount Tp _1, i.e., greater wall flow in the fuel injection during deceleration at the initial stage of acceleration than the amount corresponding to the engine load at that time When inferred,
The wall flow correction factor K ₂ proceeds to step 6 for setting a predetermined limit correction factor K ₂ ma _X. That is, when the fuel injection stop control is not performed during the deceleration operation of the engine 1, there is a wall flow larger than the amount corresponding to the engine load, and therefore, the wall flow is set to follow the wall flow increase during acceleration. setting the wall flow correction coefficient K ₂ to a value corresponding to the engine load at that time (basic fuel injection amount Tp), the air-fuel ratio is a possibility that the over-enriching becomes excessive is increase correction by wall flow correction factor K ₂ Therefore, a predetermined limit correction coefficient K _2MAX is clamped so that the wall flow correction coefficient K ₂ that is not less than a predetermined value is not set.
Therefore, the limit correction factor K ₂ ma _X, the predetermined injection amount Tp ₁
By substantially equal to or less value as the wall flow correction factor K ₂ corresponding to the basic fuel injection amount Tp is a predetermined injection amount Tp
If it is less than ₁ , the acceleration increase correction amount will be reduced, and in the initial acceleration state where the actual wall flow is large with respect to the engine load, the increase correction for wall flow correction will not be excessive. I can do it.

On the other hand, when it is determined in step 4 that the fuel injection stop control has been performed during the deceleration operation before acceleration,
In the case where the basic fuel injection amount Tp of last time is determined to be the predetermined injection amount Tp ₁ or more, the wall flow correction factor K ₂ in the basic fuel injection amount Tp which is calculated in the previous step 12 proceeds to step 7 Based on the map based on it. This wall flow correction coefficient K2
Is set to a larger value as the previous basic fuel injection amount Tp is smaller, as shown in FIG. 5, whereby the wall flow increases during acceleration operation due to the engine load (basic fuel injection amount Tp).
The delay is compensated for the increase of.

Setting the wall flow correction factor K ₂ in step 6 or step 7 is obtained by referring to a map of detection delay correction factor K ₁ in step 8. The detection delay correction factor K ₁ is intended to avoid the lean air-fuel ratio due to the hot-wire flow meter 6 for detecting lags behind the intake air flow rate Q increases rapidly at the time of acceleration, Figure 4 As shown in the figure, the throttle valve opening change rate Δθ is set so as to increase as the acceleration increases.

In step 9, obtains the operation delay correction factor K ₃ maps referred to based on the engine speed N input at step 1. The operation delay correction factor K ₃ is the time required for calculating the fuel injection amount is substantially constant, since the crank angle from when the operation trigger is generated until the operation ends becomes larger as the higher the engine speed N, the This is for correcting a response delay due to a calculation delay. As shown in FIG. 6, the larger the engine speed N, the larger the calculation delay correction coefficient K _3.
Is set so as to cope with the response delay.

In step 10, the correction coefficient set in each of the above steps
K _1, K _2, K ₃ enrichment coefficient of the intake air flow rate Q by Q
It calculates the _{INC {= 1 + (K 1} + K 3) × K 2}.

In step 12, the basic fuel injection amount Tp (= K × Q × Q _INC / N) is calculated based on the increase correction coefficient Q _INC calculated in step 10 or 11 and the engine speed N and the intake air flow rate Q input in step 1. ) Is calculated.

Here, when the engine 1 is not in the acceleration operation state, since the increase correction coefficient Q _INC is set to 1 in step 11,
The basic fuel injection amount calculated in step 12 is an amount corresponding to the intake air flow rate Q detected by the hot wire flow meter 6.

In the accelerating operation state of the engine 1, by various correction coefficients K _1, K _2, K ₃ intake air flow rate Q detected by the hot-wire flow meter 6 by is increasing correction, the fuel injection during acceleration operation By correcting various response delays of the control, it is possible to avoid over leaning of the air-fuel ratio.

Further, when the stop control of the fuel injection has not been made at the time of deceleration before acceleration operation, since there is a large wall flow than the amount corresponding to the engine load, the wall flow correction factor K ₂ a predetermined limit correction by limiting the coefficient K ₂ ma _X, the air-fuel ratio by avoiding a bulking excessive is prevented from being over-enrichment.

In step 13, the basic fuel injection amount Tp calculated in step 12 and the throttle valve opening θ input in step 1 are stored, and the respective values are used in the next steps 2, 5, and 7.

In step 14, various correction coefficients COEF set based on the engine cooling water temperature Tw detected by the water temperature sensor 12, the idling operation state of the engine 1 detected by the throttle opening sensor 8, and the like, and the correction amount Ts by the battery voltage. The final fuel injection amount Ti is set by correcting the basic fuel injection amount Tp calculated in step 12 by the above method.

In step 15, an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti set in step 14 is output to the fuel injection valve 9 at a predetermined timing, and the fuel injection valve 9 is driven to open. A predetermined amount of fuel is injected and supplied.

<Effects of the Invention> As described above, according to the present invention, when shifting from deceleration without fuel cut to acceleration, if the engine load is equal to or less than a predetermined value, the acceleration increase correction amount according to the engine load is corrected. Since the reduction is corrected, it is possible to prevent the air-fuel ratio from becoming over-rich due to the increase in acceleration at the initial stage of re-acceleration from non-fuel cut deceleration with a large wall flow rate,
There is an effect that the engine operability can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a schematic view of a system showing one embodiment of the present invention, FIG. 3 is a flowchart showing fuel injection control in the embodiment, and FIGS. 5 is a graph showing various correction coefficients used for increasing the intake air flow rate Q in the embodiment. 1 ... engine, 6 ... hot wire flow meter, 7 ... throttle valve, 8 ... throttle opening sensor, 9 ... fuel injection valve,
10 ... Crank angle sensor, 11 ... Control unit

Claims (1)

(57) [Scope of request for utility model registration] An acceleration fuel increasing means for increasing the amount of fuel supplied to the engine when the engine load is smaller during acceleration of the engine, and a deceleration fuel for cutting off the fuel supply to the engine in a predetermined deceleration operation state. When the re-acceleration from the non-cut state deceleration by the deceleration fuel cut means and the engine load is equal to or less than a predetermined value, the increase correction amount by the acceleration fuel increase means is reduced and corrected. An electronically controlled fuel injection device for an internal combustion engine, comprising: an increasing correction amount decreasing means.