JPH0447129B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel control device for an engine, and more particularly to an improved fuel control device that increases the basic fuel supply amount during acceleration.

(Prior art) Conventionally, in fuel injection engines for automobiles, the basic fuel injection amount is generally determined according to the engine operating condition determined by the intake air amount or throttle opening of the engine and the engine speed, and this basic fuel injection amount is It is designed to supply fuel to the engine based on the amount.

During acceleration, in order to ensure acceleration responsiveness, it is common to increase the basic fuel injection amount and inject the fuel asynchronously regardless of the injection timing.

For example, JP-A-54-22022 discloses that when the throttle valve is opened to a predetermined small opening or more and the idle switch provided on the throttle valve is turned off, or when the rate of change in the increasing direction of the intake air amount is A fuel control device is described that performs an increase correction when the amount exceeds a predetermined value.

(Problems to be Solved by the Invention) Conventional fuel control devices, including the fuel control device described in the above publication, determine that an acceleration state is occurring when the rate of increase in intake air amount or throttle opening reaches a predetermined value. Since the acceleration increase correction is performed uniformly, the increase correction is performed regardless of the amount of increase in the intake air amount or the amount of increase in the throttle opening.

Therefore, even when the increase in intake air amount or throttle opening is extremely small, such as when driving and stopping repeatedly during traffic stagnation, acceleration increase correction is uniformly performed and the air-fuel ratio is increased due to excessive control. There is a problem that the fuel consumption rate deteriorates due to over-richness, and the amount of unburned components in the exhaust gas increases.

(Means for Solving the Problems) The engine fuel control device according to the present invention has a first
As shown in the functional block diagram in the figure, the basic fuel supply amount is determined according to the engine operating condition determined by the engine intake air amount or throttle opening and engine speed, and the basic fuel supply amount is used to supply the engine to the engine. A fuel control device for an engine that supplies fuel is provided with a throttle opening sensor that detects the opening of the throttle valve, and detects a rate of change in the increasing direction of the throttle opening when the rate of change in the increasing direction of the throttle opening exceeds a predetermined value based on the output of the throttle opening sensor. the throttle opening sensor and the acceleration detecting means; change width detection means for detecting the change width of the throttle opening in the acceleration state in response to the output from the change width detection means; An acceleration increase limiting means is provided for limiting the above-mentioned increase correction when .

(Function) In the engine fuel control device according to the present invention, the basic fuel supply amount is determined according to the engine operating state determined by the intake air amount or throttle opening of the engine and the engine speed, and the throttle opening sensor When the rate of increase in the throttle opening detected by is equal to or higher than a predetermined value, the acceleration detection means determines that the throttle is in an acceleration state, and when the acceleration state is detected, the increase correction means performs an increase correction on the basic fuel supply amount. be done. The change width detection means detects the change width of the throttle opening in the acceleration state based on the outputs of the throttle opening sensor and the acceleration detection means, and the acceleration increase limiting means detects the change detected by the change width detection means. The above-mentioned increase correction is limited when the width is less than a predetermined value corresponding to a slight depression of the accelerator pedal.

(Effects of the Invention) According to the engine fuel control device according to the present invention, as explained above, since the basic fuel supply amount is corrected to increase during the acceleration state, acceleration responsiveness is ensured, and when the acceleration state is Since the increase correction is limited when the range of change in throttle opening is less than a predetermined value corresponding to a slight depression of the accelerator pedal, excessive control is performed by acceleration increase correction when the range of change in throttle opening is smaller than the predetermined value. Therefore, it is possible to eliminate the problem that the air-fuel ratio becomes overrich and the fuel consumption rate and exhaust gas deteriorate.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

This embodiment is an example in which the present invention is applied to a 4-stroke, 4-cylinder, vertical fuel-injection engine for an automobile.

As shown in FIG. 2, a combustion chamber 4 is formed by a cylinder block 1, a cylinder head 2, and a piston 3, and an intake valve 6 opens and closes the downstream end of an intake port 5.
and an exhaust valve 8 that opens and closes the upstream end of the exhaust port 7, an air cleaner 10 is provided at the upstream end of an intake passage 9 connected to the intake port 5, and a measuring plate is provided in the intake passage 9 in order from the upstream side. type intake air amount sensor 11 and turbo charger 1
A compressor 12b, an intercooler 13, a throttle valve 14, and a surge tank 15 are installed at the lower end of each branched intake pipe of the intake manifold portion of the intake pipe forming the intake passage 9. Injector 16 that injects fuel
is installed.

On the other hand, a turbine 12a of the turbocharger 12 is interposed in the middle of the exhaust passage 17.

Furthermore, various sensors other than the intake air amount sensor 11 include a water temperature sensor 18 that detects the temperature of cooling water in the water jacket of the cylinder block 1.
is attached to cylinder block 1, and crankshaft 1
For example, an electromagnetic pickup-type rotation speed detection sensor 20 that outputs a rotation speed signal (crank angle signal) every time the crankshaft 9 rotates 180 degrees is provided in conjunction with the crankshaft 19, and the intake passage 9 near the air cleaner 10
A first intake temperature sensor 21 is installed in the surge tank 15 to detect the intake air temperature, and a second intake air temperature sensor 21 is installed in the surge tank 15 to detect the intake air temperature after supercharging and after being cooled by the intercooler 13.
An intake temperature sensor 22 is interposed, and the throttle valve 14
For example, a potentiometer-type throttle opening sensor 23 for detecting the opening of the throttle valve 14 is provided in conjunction with the valve shaft of the throttle valve 14.

Further, the throttle valve 14 is provided with an idle switch (not shown) which is turned on until the throttle valve 14 opens by a set amount when the accelerator pedal is slightly depressed, and turned off when the throttle valve 14 is opened by more than the set amount.

And each of the above-mentioned sensors 11, 18, 20 to 23
Distributor 2 receives the detection signal from etc.
4, an injector 16, and a control unit 26 for controlling a warning lamp 25.
The control unit 26 also receives signals from an inhibitor switch 27, a gear switch 28 mounted on the transmission for detecting the gear connection state, and a voltage signal from the battery.

The control unit 26 includes an A/D converter 26 that receives detection signals from the sensors 11, 18, 20 to 23 and the battery, performs A/D conversion, and outputs the signals to the CPU 26c, as shown in FIG.
a, rotation speed detection sensor 20 and each switch 2
Receive signals from 7, 28, etc. and send the signals.
Input interface 2 that outputs to CPU26c
6b, CPU (central processing unit) 26c, and ROM
(read-only memory) 26d, RAM (random access memory) 26e, and CPU2
The output interface 26f outputs a drive signal to the injector 16, the distributor 24, etc. in accordance with the output signal from the A/D converter 26a and the input interface 2.
6b, ROM 26d, RAM 26e, and output interface 26f are connected to CPU 26c via a control bus, an address bus, and a data bus, respectively.

The ROM 26d stores in advance a control program for fuel injection amount control, a control program for ignition timing control, a memory map, and other control programs, which will be described later.

The RAM 26e is provided with a plurality of memories (temporary data storage memory, flag memory, counter memory, etc.) for storing various data as necessary.

Next, the fuel control routine carried out by the control unit 26 will be explained based on the flowchart of FIG.

In the figure, S1 to S17 indicate each step. First, when the engine starts and the control starts,
Initialization such as clearing the memory is executed in S1, then the intake air amount signal is read in S2, and then in S3 the intake air amount _Q a per cylinder is calculated using the intake air signal.

Next, in S4, the latest engine rotation speed N, which has been calculated using the rotation speed signal from the rotation speed detection sensor and stored in the memory, is determined by interrupt processing.
is read, and then in S5 the basic injection time T _P is
T _P =K・Q _a /N (K is a predetermined constant)
It is calculated using the formula and temporarily stored. This basic injection time T _P corresponds to the basic fuel injection amount for each cylinder, and represents the pulse width of the injection pulse output to the injector 16.

Next, in S6, the throttle opening signal θ from the throttle opening sensor 23 is read, and then in S7
At , it is determined whether the rate of change (increase rate) in the increasing direction of the throttle opening is dθ/dt≧A (where A is a predetermined value), and when dθ/dt≧A, the process moves to S8 and is in an acceleration state. If it is determined that this is not the case, the process moves to S14.

In S9 above, the acceleration correction C _A is calculated and temporarily stored. The acceleration correction C _A mentioned above is input and stored in advance in the ROM in the form of a memory map or arithmetic expression using the rate of increase in the throttle opening as a parameter. Qualitatively, the larger the rate of increase in the throttle opening, the larger the value. It's summery.

Next, in S10, it is determined whether the idle switch is ON (idle state) or not, and if it is ON,
The process moves to S11, and if it is determined that it is in the idle area (see FIG. 4) and is OFF, the process moves to S16.

When the engine is in an idle state, the process moves from S11 to S12, and in S12, the injection time T which is responsible for the fuel injection amount is calculated using the illustrated equation.

However, the above C _W is a water temperature correction that increases the amount to promote warming up when the cooling water temperature is below a predetermined value, and this water temperature correction C _W is stored in the ROM in a memory map using the cooling water temperature as a parameter. .
The above τ _B is a battery correction that is corrected when the battery voltage is less than a predetermined value, and this battery correction τ _B is stored in the ROM as a memory map using the battery voltage as a parameter.

Next, when the injection time comes in S13, S12, S15,
The injector is driven by the injection pulse having the pulse width of the injection time T determined in S17, and fuel is supplied to the engine, and the process returns from S13 to S2.

On the other hand, if the result of the determination in S7 is not dθ/dt≧A, the process moves from S7 to 14, and in S14 it is determined whether the idle switch is ON or not. If it is ON, the process moves from S14 to S12, and if it is OFF, the process moves to S12.
The process moves from S14 to S15, and in S15, the injection time T is calculated using the illustrated calculation formula.

However, _CE is an enrichment correction that enriches the air-fuel ratio, which was lean-controlled in the idling state when the engine is not idling, to a value below the stoichiometric air-fuel ratio (14.7) in order to increase output.

As mentioned above, even in the acceleration state, when the idle switch is ON, the range of change in the opening degree of the throttle valve 14 is very small, so the acceleration correction C _A is not executed.

The process moves from S15 to S13 and fuel injection is executed.

On the other hand, as a result of the determination in S10, when the idle switch is OFF, the engine operating state is not in the idle region, deceleration increase region, or fuel cut region (see Figure 4), so the process moves to S16 and acceleration correction is performed.
C _A is read, and then in S17, the injection time T is calculated using the illustrated formula, and the process moves from S17 to S13.

However, in the O ₂ feedback region shown in Figure 4, the enrichment correction C _E in the equation of S17 is
C _E =0 is set. Further, the above routines S2 to S17 are repeatedly executed at minute intervals of, for example, several tens of milliseconds.

By the way, the above S16 and S17 are
It may be configured like S20.

That is, if the result of the determination in S10 is that the idle switch is OFF, the process moves from S10 to S16, and S16
When the rate of increase dθ/dt of the throttle opening θ reaches a predetermined value A (when the acceleration state is entered), the range of change Θ (increase) in the throttle opening is dθ/dt.
It is calculated by integrating .

Next, in S17, the above change width Θ≧B (however, B
is a small predetermined value), and it is determined whether Θ≧B
When Θ≧B is not satisfied, the process moves from S17 to S18, and when Θ≧B does not hold, the process moves to S20.

When the width of change Θ of the throttle opening exceeds a predetermined value B, the acceleration correction C _A is read in S18,
Next, in S19, the injection time T is calculated using the illustrated formula, and then the process moves to S13, where fuel injection is executed.

In this way, when the rate of increase in the throttle opening is greater than or equal to a predetermined value and the throttle opening is not in an idling state and the throttle opening is in an accelerating state, the increase Θ in the throttle opening is a predetermined value B.
When the amount exceeds the amount, the injection time T taking into account the acceleration correction C _A is calculated, and the acceleration increase correction is executed. This acceleration increase correction improves the output and ensures acceleration response.

As a result of the determination in S17, if the increase width Θ of the throttle opening does not exceed the predetermined value B, the process moves from S17 to S20, where the injection time T is calculated using the formula shown, and the process moves from S20 to S13, where fuel injection is executed. be done.

In this way, when the increase Θ in the throttle opening after entering the acceleration state is less than the predetermined value B, the acceleration increase correction is limited and the fuel injection amount is determined without including the acceleration correction C _A.

As explained above, the acceleration increase correction is not made even in the acceleration state until the throttle opening increase width Θ reaches the predetermined value B. Therefore, when the vehicle is repeatedly running and stopping, such as when traffic is stagnant, it is necessary to accelerate slightly. In some cases, by limiting the acceleration increase correction, it is possible to prevent the air-fuel ratio from becoming overrich, save fuel, and prevent deterioration of exhaust gas.

Furthermore, although the above embodiments have been described with respect to synchronous increase in capacity, it goes without saying that the present invention can also be applied to asynchronous increase in capacity.

[Brief explanation of the drawing]

Among the drawings, FIG. 1 is a functional block diagram showing the configuration of the present invention, FIGS. 2 to 6 are related to embodiments of the present invention, and FIG. 2 is an overall diagram of an engine fuel control system according to the embodiment. Fig. 3 is a block diagram of the control system such as the control unit, Fig. 4 is a schematic flowchart of the fuel control routine carried out by the control unit of the fuel control system, and Fig. 5 shows each part of the engine operating range. Explanatory diagram showing the area, No. 6
The figure is a partial view corresponding to FIG. 4 according to a modified example. 11... Intake air amount sensor, 20... Rotation speed detection sensor, 23... Throttle opening sensor, 26
...control unit.

Claims (1)

[Claims] 1. A basic fuel supply amount is determined according to the engine operating condition determined by the intake air amount or throttle opening of the engine and the engine speed, and fuel is supplied to the engine based on this basic fuel supply amount. In the fuel control device of the supplied engine, a throttle opening sensor detects the opening of the throttle valve, and based on the output of the throttle opening sensor, acceleration is performed when the rate of change in the increasing direction of the throttle opening is equal to or higher than a predetermined value. acceleration detecting means for determining that the acceleration state is present; increasing correction means for increasing the basic fuel supply amount when the acceleration detecting means detects the acceleration state; and receiving outputs from the throttle opening sensor and the acceleration detecting means. and a change width detection means for detecting the change width of the throttle opening when the throttle opening is in an acceleration state, and when the change width detected by the change width detection means is less than a predetermined value corresponding to a slight depression of the accelerator pedal, the above-mentioned increase correction is performed. 1. A fuel control device for an engine, comprising: acceleration increase limiting means for limiting.