JPS6365150A - Fuel controller for engine - Google Patents

Abstract

PURPOSE:To prevent overrichness and unburnt components in a state of repeating running and stopping at the time of a traffic snarl or the like from occurring, by restricting the accelerating increment based on a variation in the increasing direction of throttle opening at a time when a variable range of the throttle opening is less than the specified value. CONSTITUTION:A control unit 26 operates a fundamental fuel injection quantity on the basis of each detected value of a suction air quantity sensor 11 and an engine speed detecting sensor 29, and also performs varieties of compensation on the basis of each detected value of a water temperature sensor 18, first and second suction temperature sensors 21 and 22, a throttle opening sensor 23, etc. When a variation in the increasing direction of throttle opening is more than the specified value, accelerating increment compensation is read out of a memory map according to this variation, and compensation for the fundamental fuel injection quantity is carried out. However, when the variable range found by integrating the throttle opening variation is less than the specified value, this accelerating increment compensation is skipped.

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 type engines for automobiles, the basic fuel injection amount is determined according to the engine operating condition determined by the intake air amount of the engine or the throttle opening and the engine rotational speed. Fuel is supplied to the engine based on the fuel injection 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, Japanese Patent Laid-Open No. 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.

(Problem 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 increase width of the intake air amount or the increase width of the throttle opening.

Therefore, even if the increase in intake air amount or throttle opening is very 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 in that the engine becomes overrich, resulting in poor fuel consumption and an increase in unburned components in the exhaust gas.

(Means for Solving the Problems) As shown in the functional block diagram of FIG. 1, the engine fuel control device according to the present invention provides an engine fuel control system that is determined by the intake air amount or throttle opening of the engine and the engine speed. In an engine fuel control device that determines a basic fuel supply amount according to the operating state and supplies fuel to the engine based on this basic fuel supply amount, a throttle opening sensor that detects the opening of a throttle valve is provided, and the above-mentioned Acceleration detection means is provided for determining that the acceleration state is present when the rate of change in the increasing direction of the throttle opening is greater than or equal to a predetermined value based on the output of the throttle opening sensor, and when the acceleration state is detected by the acceleration detection means; Providing an increase correction means for increasing the basic fuel supply amount, detecting the range of change in the throttle opening in an acceleration state in response to the outputs of the throttle opening sensor and the acceleration detection means,
Acceleration increase limiting means is provided for limiting the increase correction when the range of change is less than a predetermined value.

(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 degree detected in is equal to or greater than a predetermined value, the acceleration detection means determines that the vehicle is in an acceleration state, and when the acceleration state is present, the increase correction means increases the amount of fuel supplied to the basic fuel supply amount. The limiting means detects the range of change in the throttle opening in the acceleration state based on the outputs of the throttle opening sensor and the acceleration detecting means, and limits the increase correction until the range of change exceeds a predetermined value. It turns out.

(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 response is ensured, and the throttle opening is Since the increase correction is limited until the change width exceeds a predetermined value, when the change width of the throttle opening is smaller than the predetermined value, the acceleration increase correction results in excessive control and the air-fuel ratio becomes overrich, resulting in an increase in fuel consumption rate and It can eliminate the problem of exhaust gas deterioration.

(Example) Embodiments of the present invention will be described below with reference to 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 automobiles.

As shown in FIG. 2, a combustion chamber 4 is formed by a cylinder block 1, a cylinder head 2, and a piston 3, an intake valve 6 opens and closes the downstream end of an intake port 5, and an exhaust valve 6 opens and closes the downstream end of an 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 type intake air amount sensor 1) and a turbocharger are installed in the intake passage 9 in order from the upstream side. 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. An injector 16 that injects fuel is installed.

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

Furthermore, as various sensors other than the above-mentioned intake air amount sensor 1), a water temperature sensor 18 that detects the cooling water temperature in the water jacket of the cylinder block 1 is installed in the cylinder block 1.
For example, a rotation speed detection sensor 20 of an electromagnetic pickup type that outputs a rotation speed signal (crank angle signal) every time the crankshaft 19 rotates 180 degrees is installed in conjunction with the crankshaft 19, and is installed in the vicinity of the air cleaner 10. A first intake temperature sensor 21 is interposed in the intake passage 9 to detect the intake temperature, and a second intake temperature sensor 2 is installed in the surge tank 15 to detect the intake temperature after supercharging and after being cooled by the intercooler 13.
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.

Furthermore, the throttle valve 14 is provided with an idle switch (path shown) that 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 a set amount or more.

A control unit 26 is provided which receives detection signals from the sensors 1), 18, 20 to 23, etc., and controls the distributor 24, injector 16, and warning lamp 25.
6, signals from an inhibitor switch 27, a gear switch 28 attached to the transmission to detect the gear connection state, and a voltage signal from the battery are also output.

As shown in FIG. 3, the control unit 26 receives detection signals from the sensors 1), 18, 20 to 23 and the battery, performs A/D conversion, and sends the signals to the CPU 26c.
The A/D converter 26a outputs to the rotation speed detection sensor 2
0 and each switch 27, 28, etc., and outputs the signal to the CPU 26c, a CPU (central processing unit) 26C, and a ROM.
(read-only memory) 26d, RAM (random access memory) 26e, and CPU 26C
The output interface 26f outputs a drive signal to the injector 16, distributor 24, etc. according to the output signal from the A/D conversion 2H26a.
and input interface 26b, ROM 26d, and RAM
26e and the output interface 26f are connected to the CPU via a control bus, an address bus, and a data bus, respectively.
26c.

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 has a plurality of memories (temporary data storage memory,
memory for flags, memory for counters, etc.).

Next, the fuel control routine performed by the control unit 26 will be explained based on the flowchart of FIG. 4.

In the figure, 81 to 317 indicate each step. First, when the engine is started and control is started, initialization such as clearing the memory is executed in Sl, and then 8
At step 2, the intake air amount signal is read, and then at step 83, the intake air amount Q per cylinder is calculated using the intake air signal.

Next, at 84, the latest engine rotation speed N calculated using the rotation speed signal from the rotation speed detection sensor and stored in the memory is read by interrupt processing, and then at 85
, the basic injection time T.

is calculated using the formula T,=K·Q, /N (where K is a predetermined constant) and is temporarily stored. This basic injection time T 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 87, the rate of change in the increasing direction of the throttle opening (increase rate) dθ/dt≧
A (where A is a predetermined value) is determined, and dθ/dt
When ≧A, the process moves to S8, where it is determined that the acceleration state is present, and when this is not the case, the process moves to S14.

In the above S9, the acceleration correction CA is calculated and temporarily stored. The above acceleration correction CA is input and stored in the ROM in advance in the form of a memory map or arithmetic formula using the rate of increase in throttle opening as a parameter, and qualitatively, the larger the rate of increase in throttle opening, the larger the value becomes. ing.

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

31 from Sll when the above engine is in idle state
2, and in S12, the injection time T which is responsible for the fuel injection amount is calculated using the illustrated equation.

However, the above C1 is a water temperature correction that increases the amount to promote warm-up when the coolant temperature is below a predetermined value, and this water temperature correction C,1 is stored in the ROM as a memory map using the coolant temperature as a parameter. . The above τ8 is a battery correction that is corrected when the battery voltage is below a predetermined value, and in this battery correction, 3 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 82.

On the other hand, if the result of the determination in S7 is not dθ/dt≧A, the process moves from S7 to 314, and in S14 it is determined whether the idle switch is ON. If it is ON, the process moves from S14 to 312, and if it is OFF, the process moves to S14.
The process moves to step 315, and in step S15, the injection time T is calculated using the illustrated equation.

However, C4 is an enrich correction that enriches the air-fuel ratio, which was lean-controlled in the idle state when the engine is not in the idle state, to a value below the stoichiometric air-fuel ratio (14,7) for output adjustment.

As shown above, the idle switch is turned OFF even when accelerating.
When N, the variation range of the opening degree of the throttle valve 14 is very small, so the acceleration correction CA is not executed.

The process moves from S15 to S13, where fuel injection is performed.

On the other hand, as a result of the determination in the SIO, when the idle speed is OFF, the engine operating state is not in the idle region, deceleration increase region, or fuel exhaust region (see Fig. 4), so the process moves to S16 and the acceleration correction CA is performed. Then, in step 317, the injection time T is calculated using the illustrated equation, and the process moves from step S17 to step 813.

However, in the Ot feedback region shown in Fig. 4, S1
Enrich correction C1 in equation 7 is set to CE=O. Further, the routine from 82 to S17 is repeatedly executed, for example, every minute time of several IQmsec.

By the way, the above 316 and 317 are replaced by 316 to S in FIG.
It may be configured as shown in 20.

That is, when the result of the determination in SIO is that the idle switch is OFF, the process moves from SIO to 316, and in S16, the rate of increase dθ/dt of throttle opening θ reaches the predetermined value A.
The change width θ (increase width) in the throttle opening from the time when the acceleration state is reached (the time when the acceleration state is entered) is calculated by integrating dθ/dt.

Next, in 317, it is determined whether the above-mentioned change width O≧B (however, B is a predetermined small value), and if θ≧B, 31
If it moves from 7 to 318 and e≧B, S20
Move to.

When the variation width θ of the throttle opening becomes equal to or greater than the predetermined value B, the acceleration correction CA is read in 818, and then in S19
The injection time T is calculated using the equation shown in the figure, and then 3
13, where fuel injection is executed.

In this way, when the rate of increase in the throttle opening is greater than a predetermined value, the vehicle is not in an idling state, and the width of increase θ in the throttle opening after entering the acceleration state is greater than or equal to the predetermined value B, the acceleration correction CA is taken into account. The injection time T thus calculated is calculated, and acceleration increase correction is executed.

This acceleration increase correction improves the output and ensures acceleration response.

As a result of the determination in S17, the increase width θ of the throttle opening
When is not equal to or greater than the predetermined value B, the process moves from S17 to 320, where the injection time T is calculated using the formula shown in the figure, and the process proceeds to S20.
The process moves from to 313 and fuel injection is executed.

In this way, when the increase θ in the throttle opening after entering the acceleration state is less than the predetermined value 8, the acceleration increase correction is limited and the fuel injection amount is determined without including the acceleration correction OA.

In the above embodiment, it was determined whether or not to perform the acceleration increase correction based on the increase range θ of the throttle opening after entering the acceleration state, but the acceleration increase correction was determined based on the elapsed time after entering the acceleration state. It is also conceivable to configure the system to determine whether or not to do so.

As explained above, the acceleration increase is not corrected even in the acceleration state until the throttle opening increase amount θ reaches the predetermined value B, so 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 overlifted, 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 synchronous increase in capacity.

[Brief explanation of the drawing]

The functional block diagram shown in FIG. 1 showing the configuration of the present invention, and FIGS. 2 to 6 are related to embodiments of the present invention.
The figure is an overall configuration diagram of an engine fuel control device according to an embodiment, FIG. 3 is a configuration diagram of a control system such as a control unit, and FIG. 4 is a schematic flowchart of a fuel control routine performed by the control unit of the fuel control device. , 5th
The figure is an explanatory diagram showing each region within the engine operating region.
The figure is a partial view corresponding to FIG. 4 according to a modified example. 1)... Intake air amount sensor, 20... Rotation speed detection sensor, 23... Throttle opening sensor, 26... Control unit.

Claims (1)

[Claims] (1) 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 engine supplies fuel to the engine based on this basic fuel supply amount. The fuel control device includes a throttle opening sensor that detects the opening of the throttle valve, and an acceleration state when the rate of change in the increasing direction of the throttle opening is equal to or higher than a predetermined value based on the output of the throttle opening sensor. an acceleration detection means for determining the acceleration state; an increase correction means for increasing the basic fuel supply amount when the acceleration detection means detects the acceleration state; and an increase correction means for increasing the basic fuel supply amount when the acceleration state is detected by the acceleration detection means; 1. A fuel control device for an engine, comprising: an acceleration increase limiter for detecting a change width of a throttle opening at a time, and restricting the increase correction when the change width is less than a predetermined value.