JPH0458032A - Fuel control device for engine - Google Patents

Abstract

PURPOSE:To improve startability by providing a first starting pulse supplying means for the first term of start, a second starting pulse supplying means, an engine-stop detecting means for the latter term of start, and a control means for prohibiting the supply of first starting pulse at the time of restart. CONSTITUTION:A CPU30 is provided with a first starting pulse supplying means for ensuring the injection quantity required for an engine 10 for the first term of start and the injection quantity for depositing fuel to an intake manifold, a second starting pulse supplying means for supplying second starting pulse set to the injection quantity required for the engine 10 for the latter term of start, an engine-stop detecting means for detecting the engine-stop, and a control means for prohibiting the supply of the above first starting pulse at the time of restart based on the detection of engine-stop by the engine-stop detecting means. Besides, a first starting pulse width P1 and a second starting pulse width P2 are respectively set so as to increase the starting pulse width P2 at the time of low water temperature with respect to the time of high water temperature. Further, the damping quantity K is set to increase the damping quantity K at the time of low water temperature relative to the time of high water temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel control device for an engine that controls an increase in the amount of fuel injected from an injector during startup.

(Prior art) In general, the fuel supplied to the intake port and combustion chamber of an engine consists of two types: fuel that adheres to the intake pipe and enters as vaporized fuel, and fuel that enters directly from the injector along with the air flow. However, at the time of starting, the intake pipe is dry and the amount of adhesion to the intake pipe is approximately zero. Therefore, in order to quickly meet the required amount of fuel, a device for controlling the amount of fuel at the start (Japanese Patent Application Laid-Open No. 1999-1992)
(Refer to Publication No. 219327).

However, in the conventional device described above, the amount of fuel is uniformly increased from the early start to the late start, so when the temperature rises due to combustion due to cranking, the fuel adhering to the intake pipe during the early start may vaporize. Since it is supplied to the intake port, there was a problem that the air-fuel ratio could become over-rich in the late stages of startup.

In addition, when restarting the engine after stopping,
Even though fuel has already been injected from the injector and adhered to the intake pipe, the amount of fuel equivalent to the above-mentioned starting increase is injected, so the air-fuel ratio becomes overrich in the early stages of startup, which impairs restartability. There were problems that were getting worse.

(Objective of the Invention) The invention according to claim 1 of the present invention brings the fuel adhesion equilibrium state in the intake pipe early at the time of startup, and thereafter reduces the injection amount to the amount originally required by the engine, resulting in an overrich air-fuel ratio. An object of the present invention is to provide a fuel control device for an engine, which can improve startability without causing problems and also ensure good startability even when restarting the engine after it has been stopped.

The invention set forth in claim 2 of the present invention, in addition to the object of the invention set forth in claim 1, is capable of variable control of the fuel injection amount at the time of starting in accordance with the water temperature, and provides good performance especially when cold. An object of the present invention is to provide a fuel control device for an engine that can ensure startability.

(Structure of the Invention) The invention according to claim 1 of the present invention is an engine fuel control device that increases and controls the amount of fuel injection from an injector at the time of starting, and which controls the injection amount required by the engine and the intake air at the initial stage of starting. The first one takes into consideration the injection amount to deposit fuel on the pipe.
a first starting pulse supplying means for supplying a starting pulse; a second starting pulse supplying means for supplying a second starting pulse set to an injection amount required by the engine in the late stage of startup; and an engine stop detection means for detecting an engine stop. and control means for prohibiting the supply of the first starting pulse at the time of restart based on engine stop detection by the engine stop detection means.

The invention set forth in claim 2 of the present invention provides, in addition to the structure of the invention set forth above, an engine water temperature detection means for detecting the engine water temperature, and when the water temperature is low, the above-mentioned first and second An engine fuel control device is characterized in that it is provided with pulse control means for increasing each starting pulse.

(Effects of the Invention) According to the invention set forth in claim 1 of the present invention, in the initial stage of startup, the above-mentioned first starting pulse supply means adjusts the injection amount required by the engine and the injection amount that causes fuel to adhere to the intake pipe. Since the anticipated first starting pulse is supplied, the interior of the intake pipe can be quickly brought into a fuel adhesion equilibrium state in the initial stage of starting.

In addition, in the later stages of starting, the second starting pulse supplying means supplies the second starting pulse set to the injection amount required by the engine. It is possible to improve startability without causing an overrich air-fuel ratio.

Furthermore, when restarting the engine after stopping, the above-mentioned control means prohibits the supply of the first starting pulse.
Only the injection amount required by the engine is injected from the injector, which has the effect of preventing over-rich air-fuel ratio and improving restartability.

According to the invention recited in claim 2 of this invention, the above claim 1
In addition to the effects of the described invention, since the pulse control means described above increases or decreases each of the first and second starting pulses in accordance with the water temperature, the fuel injection amount at the time of starting can be variably controlled in accordance with the water temperature. This has the effect of ensuring good startability, especially when cold.

(Example) An embodiment of the present invention will be described in detail below based on the drawings.

The drawing shows a fuel control system for an engine. In FIG. 1, a hot wire air flow sensor 2 is connected to the rear of an air cleaner 1 that purifies intake air.
The system is configured to detect the amount of intake air.

A throttle body 3 is connected to the rear of the air flow sensor 2 described above, and a throttle chamber 4 within the throttle body 3 is provided with a throttle valve 5 as a control valve for controlling the amount of intake air.

A surge tank 6 as an expansion chamber having a predetermined volume is connected to the intake passage downstream of the throttle valve 5.
An intake manifold 8 communicating with the intake boat 7 is connected downstream of this surge tank 6, and this intake manifold 8
An injector 9 is disposed at the injector 9.

On the other hand, the above-mentioned intake boat 7 and exhaust port 12, which communicate with the combustion chamber 11 of the engine 10 as appropriate, include an intake valve 13 and an exhaust valve 14, which are opened and closed by a valve mechanism (not shown).
Further, an ignition plug 16 is attached to the cylinder head 15 with a spark gap facing the combustion chamber 11 described above.

02 in the exhaust passage 1-7 that communicates with the above-mentioned exhaust port 12.
A catalytic converter 19, so-called a catalyst, is connected to the rear of the exhaust passage 17 to render harmful gases harmless.

Further, an engine water temperature sensor 22 is attached to a water jacket 21- formed on the outer periphery of the above-mentioned intake manifold 8.

Figure 2 shows the control circuit of the engine fuel control device,
The PU 30 uses the start signal from the ignition switch 23, the engine speed signal from the distributor 24, the water temperature signal from the water temperature sensor 22, the throttle opening signal from the throttle sensor 25, and the intake air amount signal from the air flow sensor 2. The injector 9 is driven and controlled according to the program stored in the ROM 26, and the RAM 27 stores a map (
(See Fig. 3), map of second starting nodules with respect to water temperature (see Fig. 4), map of attenuation amount with respect to water temperature (see Fig. 5), basic fuel injection amount data, invalid injection amount data, start judgment engine Stores necessary data such as rotation speed data.

Here, the above-mentioned CPU 30 controls the engine 10 at the initial stage of startup.
A first starting pulse that provides a first starting pulse that takes into account the injection amount required by the engine and the injection amount that deposits fuel on the intake manifold 8.
a starting pulse supply means, a second starting pulse supply means for supplying a second starting pulse set to an injection amount required by the engine 10 in the late stage of starting, an engine stop detection means for detecting engine stop; and control means for prohibiting the supply of the first starting pulse at the time of restart based on the engine stop detection by the detection means.

In addition, the map shown in Fig. 3 has the water temperature on the horizontal axis and the first starting pulse width P1 on the vertical axis, and is set so that the first starting pulse width P1 is increased when the water temperature is low compared to when the water temperature is high. It is a map.

Similarly, the map shown in Figure 4 shows water temperature on the horizontal axis and second starting pulse width P2 on the vertical axis, and is set so that when the water temperature is low, the second starting pulse width P2 is increased compared to when the water temperature is high. It is a map.

Further, the map shown in FIG. 5 is a map in which the horizontal axis represents the water temperature and the vertical axis represents the attenuation amount K, and the attenuation amount K is set to be larger when the water temperature is low than when the water temperature is high, as described above.

The operation of the engine fuel control system configured as described above will be explained with reference to flowchart 1 in FIG.

In a first step 31, the CPU 30 reads various signals.

Next, in a second step 32, the CPU 30 determines whether or not the engine is being started (starting zone). In other words, by determining whether the start signal shown in FIG. 8 is ON and the engine speed is below a preset speed, for example, 500 + pm, it is possible to determine whether or not the above-mentioned starting is in progress. The process moves to the next third step 33.

In this third step 33, the CPU 30 calculates the normal injection pulse width T based on the following equation.

T=TpX (1+C)+rv Tp=Q/NXα Here, Tp is the basic fuel injection amount C is the correction amount Tv is the invalid injection amount Q is the amount of intake air N is the engine speed α is a constant.

Next, in a fourth step 34, the CPU 30 determines whether or not it is the injection timing, and when injecting fuel, the CPU 30 moves to the next fifth step 35. After driving the injector 9 and executing fuel injection, the process returns to the first step 31.

By the way, if it is determined in the second step 32 that the engine is starting, the process moves to the next sixth step 36.

In this sixth step 36, the CPU 30 determines whether or not the first starting pulse continuation counter (hereinafter simply abbreviated as counter) has timed up.

This counter is constituted by a built-in counter in the CPU, and starts holding at the same time as the ignition switch 23 is turned on at time t1 in FIG. 8, and ends holding (times up) at time t2.

If it is determined in the sixth step 36 that the counter is continuing, the process moves to the next seventh step 37.

In this seventh step 37, the CPU 30 determines whether or not the engine is stopped based on the subroutine shown in FIG.
Move to 8.

In this eighth step 38, the CPU 30 sets the starting injection pulse width P to the first starting pulse width P1, that is, at the initial stage of engine starting, in anticipation of the injection amount requested by the engine 10 and the injection amount that causes fuel to adhere to the intake manifold 8. Set the pulse width to the original value and correct the water temperature using the map shown in Figure 3.

Next, in the fourth and fifth steps 34 and 35, the CPU
'30 is the injector 9 with the above-mentioned first starting pulse width P1.
to perform fuel injection.

At the sixth step 36 described above, at time t2 (see FIG. 8) when the CPU 30 determines that the counter has timed up, the process moves to the next ninth step 39.

In this ninth step 39, the CPU 30 compares the value obtained by subtracting the attenuation amount K (see FIG. 8) from the current starting injection pulse width P[i] and the second starting pulse width P2, and calculates
When [i]-K>P2, the process moves to the next tenth step 40, and when P[i]-=P2, the process moves to another eleventh step 41.

In the tenth step 40 described above, the CPU 30 sets the starting injection pulse width P by subtracting the attenuation amount K corrected for the water temperature using the map in FIG. 5 from the previous starting injection pulse width P [i-1]. .

By repeatedly executing the processes in the ninth step 39 and the tenth step 40 described above, the first starting pulse width P1 shown in FIG. 8 is changed to the second starting pulse width P2 where P [i] -=P2. A so-called tailing process is executed to attenuate the starting injection pulse width P in stages.

In the above-mentioned eleventh step 41, the CPU 30 corrects the starting injection pulse width P to a value set to the second starting pulse width P2, that is, the injection amount required by the engine 10 in the late stage of starting, using the map shown in FIG. Set the pulse width to the specified pulse width.

Next, in the fourth and fifth steps 34 and 35, the CPU 3
0 drives the injector 9 with the above-mentioned second starting pulse width P2 to execute fuel injection.

By the way, when the CPU 30 determines that the engine is stopped in the seventh step 37 described above, the first step 37 described above is executed.
By moving to step 1 41, supply of the first starting pulse is prohibited, and the starting injection pulse width P at the time of restarting the engine after stopping is set to the second starting pulse width P2,
Below, in the fourth and fifth steps 34 and 35, the CPU 30
The injector 9 is driven again with the above-mentioned second starting pulse width P2 to execute fuel injection.

The engine stop determination process will be described below based on the subroutine shown in FIG.

That is, in a first step 51, the CPU 30 reads various signals.

Next, in a second step 52, the CPU 30 determines whether the ignition switch 23 is ON or not, and if it is ON, the process proceeds to the next third step 53.

In this third step 53, the CPU 30 determines whether the current engine speed Ne is zero or not, and if Ne<0, the process proceeds to the next fourth step 54.

In this fourth step 54, the CPU 30 determines whether the state of Ne<0 has continued for a predetermined period of time, and if the predetermined period has elapsed, the CPU 30 moves to the next fifth step 55, and in this fifth step 55, The CPU 30 determines that the engine is stopped.

In short, in the initial stage of startup, the first starting pulse supply means (see the eighth step 38) generates a first starting pulse that takes into account the injection amount required by the engine 10 and the injection amount that deposits fuel on the intake manifold 8. Since the fuel is supplied, the interior of the intake manifold 8 can be quickly brought into a fuel adhesion equilibrium state in the initial stage of startup.

In addition, in the late stage of starting, the second starting pulse supply means (see step 11 41) described above supplies the second starting pulse set to the injection amount requested by the engine 10, so that the injection amount is By reducing the amount, the air-fuel ratio will not become overrich in this late stage of startup.
This has the effect of improving starting performance.

Furthermore, when restarting the engine after stopping, the CPU 30 described above prohibits the supply of the first starting pulse, so that only the injection amount requested by the engine 10 (the injection amount corresponding to the second starting pulse) is sent from the injector 9. is injected,
This has the effect of preventing over-rich air-fuel ratio and improving restartability.

Furthermore, since the above-mentioned first starting pulse and second starting pulse are corrected for the water temperature using the maps shown in FIGS. 3 and 4, the fuel injection amount at the time of starting can be variably controlled in accordance with the water temperature. This has the effect of ensuring good startability when cold.

In the correspondence between the structure of the present invention and the above-described embodiment, the intake pipe of the present invention corresponds to the intake manifold 8 of the embodiment, and similarly, the first starting pulse supply means is the eighth starting pulse supply means controlled by the CPU 30.
Corresponding to step 38, the second starting pulse supply means starts the first starting pulse under the control of the CPU 30.
1 step 41, the engine stop detection means corresponds to the seventh step 37 controlled by the CPU 30, the control means corresponds to the CPU 30, the engine water temperature detection means corresponds to the water temperature sensor 22, and the pulse control means corresponds to the seventh step 37 controlled by the CPU 30. , the maps stored in the RAM 27 (see FIGS. 3 and 4), however, the present invention is not limited to the configuration of the above-described embodiment.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, FIG. 1 is a system diagram showing an engine fuel control device, FIG. 2 is a control circuit block diagram, and FIG. 3 is an explanation showing a water temperature correction map of the first starting pulse width. Figure 4 is an explanatory diagram showing the water temperature correction map for the second starting pulse width, Figure 5 is an explanatory diagram showing the water temperature correction map for the attenuation amount, Figure 6 is a flowchart showing the fuel injection process, and Figure 7 is A flowchart showing the engine stop determination process, and FIG. 8 is a time chart. 8... Intake manifold 9... Injector 10... Engine 22... Water temperature sensor 30... CPU (control means) 37... Seventh step (engine stop detection means) 38... Eighth step (First starting pulse supply means) 4
1...11th step (second starting pulse supply means) 3O-CPU (control 'a') Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6u □ Water temperature (''C) 6th factor Fig. 7

Claims (2)

[Claims] (1) An engine fuel control device that controls an increase in the amount of fuel injected from an injector at the time of startup, and includes an engine fuel control device that takes into consideration the amount of injection required by the engine and the amount of injection that deposits fuel in the intake pipe at the beginning of startup. a first starting pulse supply means for supplying one starting pulse; a second starting pulse supply means for supplying a second starting pulse set to an injection amount required by the engine in a late stage of startup; and an engine stop for detecting engine stop. A fuel control device for an engine, comprising: a detection means; and a control means for prohibiting supply of the first starting pulse at the time of restart based on engine stop detection by the engine stop detection means. (2) The engine fuel according to claim 1, further comprising engine water temperature detection means for detecting engine water temperature, and pulse control means for increasing each of the first and second starting pulses when the water temperature is low compared to when the water temperature is high. Control device.