JPH0249940A - Internal combustion engine fuel supply control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fuel supply control device for an internal combustion engine that performs preliminary injection for forming a premixture.

<Prior art> While each cylinder is equipped with a main fuel injection valve, an auxiliary fuel injection valve is provided upstream of the intake passage to perform preliminary injection, form a premixture, and increase charging efficiency through the cooling effect of vaporization heat. There are also some that are designed to improve flammability.

In addition, in a device that performs this type of premixture formation, an ultrasonic atomization device is installed downstream of the auxiliary fuel injection valve, and the fuel injected from the auxiliary fuel injection valve is made to adhere to the vibrator of the ultrasonic device and become atomized. A device designed to promote the change in speed has become common (see Japanese Utility Model Application Publication No. 62-200157, etc.).

<Problems to be Solved by the Invention> By the way, in conventional devices of this type, the injection amount ratio (
The injection rate (hereinafter referred to as injection rate) is fixed to a preset value, but during transient operation, if the injection rate by the auxiliary fuel injection valve, that is, the premixing rate is high, the auxiliary fuel injection valve is installed on the upstream side. This increases the delay in the supply of pre-injected fuel to the combustion chamber due to adhesion to the intake passage wall, causing the air-fuel ratio to become lean during acceleration and rich during deceleration, impairing transient driving performance. Ta.

The present invention was developed in view of these conventional problems. During transient operation, the injection rate of the auxiliary fuel injector is reduced at a reduction rate according to the operating condition, thereby suppressing changes in the air-fuel ratio and reducing transient operation. The purpose is to improve driving performance.

In addition, after changing the injection rate during transient operation in this way, when transitioning to steady operation, if the injection rate of the front injector is changed at the same time, the air-fuel ratio will fluctuate due to the difference in fuel supply delay. .

Therefore, in this case, the second objective is to suppress fluctuations in the air-fuel ratio by delaying changes in the injection rate of the main fuel injector.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention includes a main fuel injection valve that injects fuel to each cylinder, and also injects fuel to all cylinders in the upstream portion of the intake passage. In a fuel supply control device for an internal combustion engine that includes an auxiliary fuel injection valve for forming a premixture, a throttle valve opening rate change detection means for detecting a rate of change in a throttle valve opening degree of the engine; and an injection rate, which is a ratio of the injection amount from the auxiliary fuel injection valve to the total injection amount from the main fuel injection valve and the auxiliary fuel injection valve, as a rate of change in the throttle valve opening during transient operation. The premixing ratio control means is configured to reduce the premixing ratio based on the detected value of the cooling water temperature.

In addition, in order to achieve the second objective, a first prediction is made to reduce the injection rate, which is the ratio of the injection amount from the auxiliary fuel injection valve to the total injection amount from the main fuel injection valve and the auxiliary fuel injection valve, during transient operation. a mixture ratio control means; when transitioning from transient operation to steady operation, the injection rate of the main fuel injector is adjusted to the steady state operation with respect to the rate of change in which the injection rate of the auxiliary fuel injector returns to the injection rate during steady operation; and second premixing ratio control means for controlling the rate of change to return to the original injection rate with a delay.

Effect> During transient operation, the injection rate of the auxiliary fuel injection valve is controlled by the premix ratio control means based on the rate of change of the throttle valve opening and the detected value of the cooling water temperature.

Here, it is possible to estimate the amount of pre-injected fuel adhering to the intake passage wall surface in accordance with the degree of transient based on the rate of change of the throttle valve opening degree and the cooling water temperature. Therefore, by reducing the injection rate of the auxiliary fuel injection valve in proportion to the supply delay with respect to the deposited amount, changes in the air-fuel ratio can be effectively suppressed.

Further, after the first premixing control means reduces the injection rate of the auxiliary fuel injection valve during transient operation by the method described above, the second premixing ratio control means decreases the injection rate of the auxiliary fuel injection valve when transitioning to steady operation. Since the rate of change in the injection rate of the main fuel injection valve is controlled with a delay with respect to the rate of change in the injection rate of the valve, fluctuations in the air-fuel ratio during this time are also suppressed.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 2 showing the configuration of one embodiment, an internal combustion engine 1 is equipped with a main fuel injection valve 3 that injects fuel at a predetermined timing for each intake port of each cylinder of an intake manifold 2, and a throttle valve 4. An auxiliary fuel injection valve 5 that injects fuel to all cylinders is installed at the upstream side of the intake passage near the upstream side (or downstream side) of the engine.

A vibrator 6A of an ultrasonic atomization device 6 is provided near the downstream side of the throttle valve 4, and the fuel injected from the auxiliary fuel injection valve is attached thereto and atomized by ultrasonic vibration.

A throttle sensor 7 that detects the opening degree of the throttle valve 4 is connected to the throttle valve 4, and an air flow meter 8 that detects the intake air flow rate Q is provided upstream of the throttle valve 4 of the intake manifold 2. In addition, there is a crank angle sensor 9 for detecting the engine rotation speed N, a water temperature sensor 10 as a cooling water temperature detecting means, a 0□ sensor 11 for detecting the oxygen concentration in exhaust gas to detect the air-fuel ratio for air-fuel ratio feedback control, etc. Each signal from is input to the control unit 12,
Based on these signals, the control unit 12
The fuel injection amount and injection timing from the main fuel injection valve 3 and the auxiliary fuel injection valve 5 are set according to the operating state.

Next, fuel injection control by the control unit 12 will be explained according to the flowchart shown in FIG.

In step 1 (denoted as S in the figure), signals from various sensors are read.

In step 2, the basic injection pulse width MT when the fuel injection amount for each cylinder per engine rotation is obtained only by the main fuel injection valve 3 is calculated using the following equation.

M T F ""K' Q/N In step 3, the engine rotation speed N and the MT.

Based on this, the premix ratio KRBINJ corresponding to the steady operating state is searched from the map stored in the ROM.

In step 4, the difference between the current value and the previous value of the throttle valve 4 opening degree θ detected from the throttle sensor 7, that is, the rate of change Δθ of the throttle valve opening degree is calculated. Therefore, the throttle sensor 7 and the function of step 4 constitute a throttle valve opening change rate detection means.

In step 5, it is determined whether the throttle valve opening degree change rate Δθ is 0 or not.

If it is determined that the transient operating state is not 0, step 6
, and calculates the basic premixing rate reduction rate TDAPR from the map stored in the ROM based on the throttle valve opening change rate Δθ.
[! Search for.

Here, TDAPRE is set to be large as the absolute value of Δθ is large, but during deceleration (Δθ 0), the effect of enrichment due to the inflow of the fuel wall flow before deceleration is large; It is set larger than during acceleration (Δθ>O) (see FIG. 5(A)).

Next, the process proceeds to step 7, where R is determined based on the cooling water temperature (hereinafter referred to as water temperature) TI- detected by the water temperature sensor 10.
The pre-mixing vehicle rate reduction rate water temperature correction factor TTPRE is searched from the map stored in the OM. Here, TTPRII! is set to be thicker (see FIG. 5(B)) because the lower the water temperature T and 4, the greater the amount of water that adheres as a wall flow without being vaporized (see FIG. 5(B)).

In step 8, the retrieved basic premix ratio KRB
The premixing rate RBINJ is calculated by the following formula based on INJ, the basic premixing unit rate reduction rate TDAPRE, and the premixing unit rate decrease rate water temperature correction factor TTPRH.

RBINJ-KRBINJ-TDAPREXTTPR
EThis premix ratio RBINJ is a value corresponding to the injection rate, which is the ratio of the injection amount of the auxiliary fuel injection valve 5 to the total injection amount from the main fuel injection valve 3 and the auxiliary fuel injection valve 5, and therefore, each of the above maps and steps The function of 6.7°8 corresponds to the premixing ratio control means (first premixing ratio control means).

On the other hand, in the judgment in step 5, the throttle valve opening degree change rate Δθ is 0.
．． That is, when it is determined that the operating state is steady, the process proceeds to step 9, where it is determined whether the difference between the previously set corrected premixing ratio RBINJ -+ and the basic premixing ratio RBINJ is 0.

When Δθ is not O, that is, when transition is made from transient operation to steady operation, the process proceeds to step lO, and the premixing change rate TBI
NJ is calculated using the following formula.

T81NJ=T. . .

Next, proceeding to step 1, a premixing change rate correction value KBINJ for delaying the change rate of the injection rate of the main fuel injection valve 3 with respect to the change rate of the injection rate of the auxiliary fuel injection valve 5 is calculated using the following equation.

KBINJ = INJN XKINJTWXKTNJ
TVOXKINJSB Here, INJN is the engine rotation speed N, KINJTW is the water temperature TWI, INJTVO is the throttle valve opening θ, and KINJSB is the injection pulse width STi of the auxiliary fuel injection valve 5, respectively, as shown in FIG. It is a coefficient.

Next, the process proceeds to step 12, where the previous corrected premixing ratio RB
The calculated premixing change rate TBINJ is added to INJ −+.
A new corrected premixing ratio RBINJ is set by adding .

In step 13, a coefficient MRBINJ for setting the injection rate of the main fuel injection valve 3 is calculated using the following equation.

MRBINJ =RBINj −++TBINJ XK
In the BINJ step 14, the premix ratio RBINJ and the basic premix ratio KRBINJ are compared, and IIBINJ≦KII
If BINJ, proceed to step 15 and convert the basic premixing ratio KRBINJ to the latest premixing ratio RBINJ and coefficient MR.
Update as BINJ, but RBINJ > RBIN
In the case of J, the premixing ratio has already reached the basic premixing ratio KRBINJ, which is the set value during steady state, so this routine ends.

Note that even when the determination in step 9 is 0, step 15
Proceed to.

Next, a routine for calculating the fuel injection amount MTi and STI from the main fuel injection valve 3 and the auxiliary fuel injection valve 5 using the premix ratio RBINJ and the coefficient MRBINJ will be explained with reference to FIG.

In step 21, the effective injection noggle width MT of the main fuel injection valve 3 is calculated using the following equation.

MT, -MT, ・α・K, ・C0EF・ (1-M
RBINJ) Here, α is 0. A feedback correction coefficient K for air-fuel ratio feedback control that is set by proportional-integral control or the like based on a signal from the sensor 11.

C0EF is a learning correction coefficient for improving responsiveness during transient operation by bringing the feedback correction coefficient α closer to the reference value.
indicates various correction coefficients set based on water temperature, etc.

In step 22, the final fuel injection pulse width MT of the main fuel injection valve 5 is determined every 1/2 revolution of the engine.

is calculated using the following formula.

MT, = 2XMT, +MTs where MT is the invalid injection pulse width of the main fuel injection valve 3 based on the battery voltage.

゛In step 23, the MT performs basic injection when one auxiliary fuel injection valve 5 obtains the total injection amount per engine revolution when a corresponding injection amount is injected by the main fuel injection valves 3 for the number of cylinders. The pulse width S TF is calculated using the following equation.

STP = MT, ・K.

However, K5 indicates the ratio of the injection pulse widths of the auxiliary fuel injection valve 5 and the main fuel injection valve 3 for the same flow rate, and this value is determined depending on the number of fuel injection valves and the difference in flow rate characteristics.

In step 24, the effective injection pulse width ST of the auxiliary fuel injection valve 5 is calculated using the following equation.

ST, =ST, .alpha..C0EF-RBINJ In step 25, the final fuel injection pulse width STi from the auxiliary fuel injection valve 5 is calculated using the following equation.

ST 5 = 1/2XST, +STs However, 1/2
The coefficient is 2 per revolution of the engine when the auxiliary fuel injector 5
This is to perform multiple injections, and S T s is based on the battery voltage (ineffective injection pulse width of the auxiliary fuel injection valve 5).

An injection pulse having the pulse width STt set as described above is output to the auxiliary fuel injection valve 5 for preliminary injection every time the reference crank angle signal is input from the crank angle sensor 8.

Note that fuel injection from the main fuel injection valve 3 for each cylinder is also performed at the same cycle.

If such control is performed, during transient operation, the auxiliary fuel injection valve 5 is corrected to reduce the premix ratio RBINJ based on the degree of acceleration/deceleration determined by the rate of change Δθ of the throttle valve opening and the water temperature T'w. It is possible to effectively suppress fluctuations in the air-fuel ratio due to fuel injected into a wall flow (see the solid line in FIG. 7(A); the dotted line indicates when the premix ratio RBINJ is not reduced).

In addition, when transitioning from transient operation to steady operation, the response of the air-fuel ratio change due to the fuel injected from the main fuel injection valve 3 to the change in air-fuel ratio due to the fuel injected from the auxiliary fuel injection valve 5 is quick, so the auxiliary If the rate of change in the injection rate of the fuel injector 5 to return to the steady state injection rate is the same as the rate of change to return the injection rate of the main fuel injector 3 to the steady state injection rate, the air-fuel ratio will increase. Although it changes (see the dotted line in Figure 7 (B)), the second
In this embodiment including the invention, since the former rate of change is delayed from the latter rate of change, changes in the air-fuel ratio can be suppressed (see the solid line in FIG. 7(B)).

<Effects of the Invention> As explained above, according to the present invention, the injection rate and the rate of change in the injection rate of the main fuel injector and the auxiliary fuel injector are controlled during transient operation and during transition from transient operation to steady operation. Through proper control, fluctuations in the air-fuel ratio can be suppressed as much as possible.
Drivability and exhaust emission characteristics can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of the present invention.
FIG. 3 is a diagram showing the configuration of an embodiment of the present invention, and FIG.
5(A) is a flowchart showing the fuel injection amount setting routine of the above embodiment; FIG. B) is a diagram showing the relationship between the correction coefficient of the premixing ratio and the water temperature, and FIG. Is it also water? Coefficient for IA'r. The same figure (C) is a diagram showing coefficients and similar state quantities for the throttle valve opening, and the same figure (B) is a diagram showing various state quantities when transitioning from transient operation to steady operation in the same example. be. 1... Engine 3... Main fuel injection valve 5... Auxiliary fuel injection valve 7... Throttle sensor 8...
・Air flow meter 9...Crank angle sensor
10...Water temperature sensor 12...Control unit No. 2111 Fig. 4 Fig. #f5 (A) (B)

Claims (2)

[Claims] (1) Fuel supply for an internal combustion engine that is equipped with a main fuel injection valve that injects fuel into each cylinder and an auxiliary fuel injection valve that injects fuel into all cylinders upstream of the intake passage for forming a premixture. In the control device, a throttle valve opening change rate detection means for detecting a change rate of a throttle valve opening of the engine, a cooling water temperature detection means for detecting a cooling water temperature of the engine, and the main fuel injection valve and the auxiliary fuel injection Premixing ratio control means that reduces the injection rate, which is the ratio of the amount of injection from the auxiliary fuel injection valve to the total amount of injection from the valve, based on the detected value of the rate of change in the opening of the throttle valve and the temperature of the cooling water during transient operation. A fuel supply control device for an internal combustion engine, comprising: (2) Fuel supply for an internal combustion engine that is equipped with a main fuel injection valve that injects fuel into each cylinder and an auxiliary fuel injection valve that injects fuel into all cylinders upstream of the intake passage for forming a premixed mixture. In the control device, a first premixing ratio control means for reducing an injection rate, which is a ratio of the injection amount from the auxiliary fuel injection valve to the total injection amount from the main fuel injection valve and the auxiliary fuel injection valve, during a transient operation; When transitioning from operation to steady operation, the injection rate of the main fuel injector is changed to return to the injection rate during steady operation relative to the rate of change in which the injection rate of the auxiliary fuel injector is returned to the injection rate during steady operation. 1. A fuel supply control device for an internal combustion engine, comprising: second premix ratio control means for controlling the speed with a delay.