JPH0465217B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an electronically controlled fuel injection device, and is particularly suitable for use in controlling an automobile engine. The present invention relates to an electronically controlled fuel injection device that increases the warm-up amount according to the warm-up state.

[Conventional technology]

2. Description of the Related Art One of the methods for supplying an air-fuel mixture at a predetermined air-fuel ratio to the combustion chamber of an internal combustion engine such as an automobile engine uses an electronically controlled fuel injection device. In this method, an injector for injecting fuel into the engine is installed in the intake manifold or throttle body of the engine, for example, in several or one engine cylinder, and the valve opening time of the injector is adjusted depending on the operating state of the engine. By controlling the air-fuel mixture, an air-fuel mixture with a predetermined air-fuel ratio is supplied to the engine combustion chamber. In this electronically controlled fuel injection system, the basic fuel injection amount (hereinafter referred to as the basic injection amount) is usually determined from the engine load detected from the intake air amount or intake pipe pressure of the engine and the engine rotation speed. When the cooling water temperature is low, the basic injection amount is increased by warm-up based on signals from sensors installed in various parts of the engine, such as signals from the engine's cooling water temperature sensor, and the actual fuel injection is performed. (hereinafter referred to as the effective injection amount). This warm-up increase is done to ensure drivability during warm-up. Considering that the air-fuel ratio tends to be lean during warm-up, it is thought that the engine cooling water reflects the warm-up condition. The basic injection amount is increased in accordance with the temperature of the engine. The increase value for this warm-up increase is as shown in Figure 1, for example. Normally, the temperature of the engine coolant is set at 70℃, and the increase ratio is set to increase as the temperature decreases from this point. be done. By the way, this warm-up increase value can be reduced during the so-called idling state, since the required air-fuel ratio is lower than when a load is applied. The amount of decrease in this warm-up increase value can be increased as warm-up progresses, but at extremely low temperatures, the amount of decrease cannot be increased very much.

[Problem to be solved by the invention]

However, in the case of conventional warm-up increase, after determining the basic warm-up increase value based on the temperature of the engine cooling water, depending on whether the engine is in an idling state or not, as shown by the broken line in Fig. 1, It was decided that this would be uniformly corrected, and the amount of reduction would be kept small in order to ensure idle rotation performance at extremely low temperatures. As a result, when the engine is already warmed up and the engine is idling, an unnecessary increase in warm-up volume is required, which not only deteriorates fuel efficiency but also causes a large amount of CO, HC, etc. to be emitted. Ta. The present invention has been made by focusing on these conventional problems, and eliminates problems such as a decline in idle rotation performance at extremely low temperatures, and eliminates unnecessary fuel injection when warm-up progresses. The purpose of this invention is to provide an electronically controlled fuel injection device that can reduce CO, HC, and other emissions while improving fuel performance.

[Means to achieve the task]

As summarized in FIG. 2, the present invention determines the basic injection amount according to the engine load and engine speed, and increases the basic injection amount according to the warm-up state of the engine. In the electronically controlled fuel injection device, the warm-up state detection means detects the warm-up state of the engine, the idle detection means detects that the engine is in the idle state, and the warm-up state detection means detects the warm-up state of the engine. a warm-up increase value calculation means for calculating an increase value; a correction amount calculation means for calculating a correction amount of the warm-up increase that tends to increase as warm-up progresses according to the warm-up state; and the idle detection unit. Warm-up increase means for subtracting the correction amount from the warm-up increase value when the idle state is detected by the means, and increasing the warm-up amount according to the warm-up state according to this result; The above object has been achieved by having the following.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. An embodiment of an automobile engine equipped with an electronically controlled fuel injection device that senses the amount of intake air, to which the present invention is adopted, has an air flow meter for detecting the flow rate of intake air, as shown in FIGS. 3 and 4. 12, an intake temperature sensor 14 built into the air flow meter 12 for detecting the temperature of intake air, and an accelerator pedal (not shown) disposed on the driver's seat for controlling the flow rate of intake air. a throttle valve 16 that opens and closes in conjunction with the throttle valve 16; a throttle sensor 18 for detecting the opening degree of the throttle valve 16 and its rate of change; and a surge tank 20 for preventing intake interference.
, an injector 24 disposed in the intake manifold 22 for injecting pressurized fuel toward the intake port of each cylinder, and a spark plug 26 for igniting the air-fuel mixture introduced into the engine combustion chamber 10A. , an exhaust manifold 28 , and an oxygen concentration sensor (hereinafter referred to as an O ₂ sensor) 29 disposed in the exhaust manifold 28 for sensing the rich/lean performance of the air-fuel ratio from the residual oxygen concentration in the exhaust gas. an igniter 30 that generates a primary ignition signal; an ignition coil 31 that converts the primary ignition signal generated by the igniter 30 into a high-voltage secondary ignition signal; and a secondary ignition signal generated by the ignition coil 31. A distributor 3 having a distributor shaft 32A that rotates in conjunction with the crankshaft of the engine 10 for distributing signals to the spark plugs 26 of each cylinder.
2, a cylinder discrimination sensor 34 and a rotation angle sensor 36 built into the distributor 32 and for outputting a cylinder discrimination signal and a rotation angle signal, respectively.
and a water temperature sensor 38 disposed on the cylinder block 10B of the engine 10 for detecting the engine cooling water temperature, which is considered to reflect the warm-up state.
, a neutral switch 33 for detecting whether the shift position of the automatic transmission 41 is in the neutral range or the parking range; and a neutral switch 33 for detecting the running speed of the vehicle from the rotational speed of the output shaft of the automatic transmission 41. The basic injection amount is determined from the vehicle speed sensor 35, the intake air amount detected from the output of the air flow meter 12, and the engine rotation speed detected from the output of the rotation angle sensor 36, and the state of the engine is determined from the information from the various sensors. An electronic control unit (hereinafter referred to as ECU) determines the basic injection amount, corrects the basic injection amount by, for example, increasing the amount for warming up, and outputs an injection signal to the injector 24.
) 40, and . As shown in detail in FIG. 4, this ECU 40 is a central processing unit (hereinafter referred to as a
(referred to as CPU) 40A, and a clock circuit 40 that generates various clock signals.
B and read-only memory (hereinafter referred to as ROM) for storing control programs and various data in advance.
) 40C, and a random access memory (hereinafter referred to as
(referred to as RAM) 40D, and buffers 12a, 14a, 38a for analog signals such as the output of the air flow meter 12, the output of the intake temperature sensor 14, and the output of the water temperature sensor 38, respectively.
multiplexer 40E for sequentially capturing via
, an analog-to-digital converter (hereinafter referred to as A/D converter) 40F for converting the output of the multiplexer 40E into a digital signal, and an output of the A/D converter 40F and a buffer 35a.
an input/output port 40G for taking in the vehicle speed sensor output 35 via the cylinder discrimination sensor 34 and the rotation angle sensor 36;
a shaping circuit 40H for shaping the waveform of the output; and a shaping circuit 40H for shaping the waveform of the output;
Input/output port 4 for receiving _O2 sensor 29 output
0I, an output port 40K for outputting an ignition command signal to the igniter 30 via a drive circuit 40J in accordance with the calculation result of the CPU 40A, and an output port 40K for outputting an ignition command signal to the igniter 30 via the drive circuit 40L in accordance with the calculation result of the CPU 40A. An output port 40M for outputting a valve opening time signal to the injector 24, and a Romon bus 40N for connecting each component.
It consists of and. The operation will be explained below. First, electronic control unit 4
0 is the intake air amount Q of the air flow meter 12 output
and the engine rotation speed N calculated from the cylinder discrimination sensor 34 and rotation angle sensor 36 outputs,
The basic injection time Tp is calculated using the following formula. Tp=K・(Q/N)...(1) Here, K is a coefficient. Furthermore, by correcting the basic injection time Tp using the following formula according to the signals from each sensor,
Calculate TAU from the execution injection time. TAU=Tp・f(A/F)・f(WL)・f(THA) {1+f
(AEW)}{1=f(RS)}...(2) Here, f(A/F) is the air-fuel ratio correction coefficient, f
(WL) is a warm-up increase correction coefficient, f (THA) is an intake air temperature correction coefficient, f (AEW) is a warm-up acceleration increase correction coefficient, and f (RS) is a reduction coefficient. A fuel injection signal corresponding to this effective injection time TAU is output from the output port 40M to the injector 24 via the drive circuit 40L, and in synchronization with the engine rotation, the injector 24 outputs the effective injection time TAU.
is opened to inject a predetermined amount of fuel into the intake manifold 22 of the engine. Here, the warm-up increase in the present invention is performed as follows. That is, as shown in FIG.
First, in step 110, a basic warm-up increase value WL is searched from the WL map previously stored in the ROM 40C in accordance with the temperature of the engine coolant, using a method similar to the conventional method. Next, in step 112, the throttle sensor 18 detects whether the throttle valve 16 is fully closed or not, thereby determining whether or not the engine is in an idling state. When it is detected that it is fully closed, the step
Proceed to step 114 to detect whether the temperature of the engine cooling water is 0°C or higher. And when the temperature is above 0℃, step
Proceed to step 116 and find the basic warm-up increase value as shown in equation (4).
The amount by which WL is reduced by 10% is the corrected warm-up increase value WL. WL←WL−10% ...(4) On the other hand, if the temperature is less than 0℃, proceed to step 118.
As shown in formula (5), the warm-up increase value is modified by reducing the basic warm-up increase value WL by 5%.
Let it be WL. WL←WL−5% (5) When the throttle valve 16 is not fully closed, this correction step is bypassed and the basic warm-up increase value WL is adopted as is. As a result, the warm-up increase value is as shown in Figure 6.
The amount of correction at idle becomes two different levels when the temperature reaches 0°C. Furthermore, this warm-up increase value WL
is calculated as f(WL) by the following formula,
This is reflected in the calculation of equation (2). f(WL)=1+f(N)×WL...(6) Here, f(N) is the rotational speed correction term. FIG. 7 shows another embodiment of the method of the present invention. In this embodiment, in step 120, a warm-up increase correction value ΔWL based on a function shown in FIG. 8 according to the engine coolant temperature is searched from a diagram stored in the ROM 40C. , step 122
Appropriate modifications will be made. In this way, instead of just two stages as in the previous embodiment, the ninth stage
As shown in the figure, the warm-up amount can be increased very precisely and appropriately. Other configurations/
The operation is the same as in the previous embodiment. The present invention can be applied not only to an electronically controlled fuel injection type engine that senses the amount of intake air as described above, but also to an engine that senses intake pipe pressure in the intake manifold 22, or other electronically controlled fuel injection type engines. Needless to say.

【Effect of the invention】

As explained above, according to the present invention, the correction of the warm-up increase value, which was conventionally performed uniformly, can be performed more precisely and appropriately, and as a result, the warm-up increase can be made in accordance with the actual situation. Unnecessary fuel injection when warm-up progresses can be suppressed without causing problems such as a decline in idle rotation performance at extremely low temperatures. Therefore, it is possible to improve fuel efficiency, and
This has the effect of reducing emissions of CO, HC, etc. and improving exhaust gas purification performance.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the warm-up increase value according to the conventional warm-up increase method, FIG. 2 is a block diagram showing the electronically controlled fuel injection device according to the present invention, and FIG. 3 is a diagram showing the warm-up increase value according to the conventional warm-up increase method. FIG. 4 is a sectional view, including a partial block diagram, showing the configuration of an embodiment of the intake air amount sensing type electronically controlled fuel injection device for an automobile engine.
FIG. 5 is a block diagram showing an example of the configuration of the electronic control unit used in the embodiment, FIG. 5 is a flow chart showing the warm-up fuel increase routine, and FIG. 6 is a flow chart showing the warm-up fuel increase value. 1 is a diagram corresponding to FIG. 1, FIG. 7 is a flowchart corresponding to FIG. 5 according to another embodiment of the present invention, FIG. The figure is a diagram corresponding to FIG. 1 showing the warm-up increase value. 16...Throttle valve, 18...Throttle sensor, 24...Injector, 38...Water temperature sensor, 40...Electronic control unit, WL...Warm-up increase value, f(WL)...Correction coefficient, Tp ...Basic injection time.

Claims (1)

[Scope of Claims] 1. In an electronically controlled fuel injection system that determines a basic injection amount according to engine load and engine speed, and increases the basic injection amount according to the warm-up state of the engine. , warm-up state detection means for detecting a warm-up state of the engine; idle detection means for detecting that the engine is in an idle state; and a warm-up increase value for determining a warm-up increase value according to at least the warm-up state. a calculation means; a correction amount calculation means for calculating a correction amount for a warm-up increase that tends to increase as warm-up progresses according to the warm-up state; and an idle state detected by the idle detection means. In some cases, the engine is characterized by comprising a warm-up amount increasing means for subtracting the correction amount from the warm-up amount increase value and performing a warm-up amount increase according to the warm-up state according to this result. Electronically controlled fuel injection device.