JPH0571380A - Device for feeding fuel during start of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve low temperature startability of an engine by providing special constitution for a feed means of mixture fuel during the start of an engine and for control of a fuel feed amount. CONSTITUTION:It is decided at S1 whether or not a starter switch is turned ON and it is decided at S2 whether or not a water temperature Tw read based on a detecting signal outputted from a water temperature sensor us below -20 deg.C. It is decided at S3 whether or not alcohol concentration ALC read based on a detecting signal outputted from an alcohol concentration sensor exceeds M60. It is decided at S5 whether or not the number N of cranking revolutions of an engine read based on a detecting signal outputted from a number of revolution sensor is below 100 r.p.m. An auxiliary fuel injection valve is turned ON and fuel is injected from the auxiliary injection valve at integral 6 and S7. Based on current alcohol concentration, a water temperature, and the number of cranking revolutions, an amount of fuel injected by a fuel injection valve during starting is decided at S4 and S8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for starting an internal combustion engine which uses a mixed fuel prepared by mixing a plurality of types of fuel, and more particularly to a technique for improving cold startability.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine which uses a mixed fuel in which a fuel such as alcohol (mainly methanol) and a fuel such as gasoline are mixed, for example, the concentration of methanol in the fuel and the engine The amount of fuel supply at the time of starting was controlled based on the cooling water temperature to keep the complete explosion time within the standard.

For example, in the state of -20 ° C. or lower, the fuel supply amount at the time of starting is increased along with the increase of the methanol concentration in the fuel. Also, with this,
The amount of fuel increase and the period of fuel increase were increased after the engine was started to maintain good connection of the fuel supply amount.

[0004]

However, for example, when a high-concentration alcohol fuel having an alcohol concentration of M85 (85% alcohol, 15% gasoline) (especially M60 or more) is used, at a low temperature, particularly -25 °. There was a problem that starting with C was difficult. The minimum starting temperature of the engine is guaranteed at -30 ° C.

In view of the conventional problems as described above, the present invention provides a low temperature startability of the engine by providing a unique structure to the mixed fuel supply means and the fuel supply amount control at the time of engine start. The purpose is to improve.

[0006]

Therefore, as shown in FIG. 1, the starting fuel supply system for an internal combustion engine according to the present invention is provided for each cylinder in the intake passage of the engine and mixes a plurality of types of fuel. The main fuel supply means for supplying the mixed fuel, the auxiliary fuel supply means for supplying the mixed fuel, which is provided in the upstream side of the intake passage, the water temperature detecting means for detecting the cooling water temperature of the engine, and the mixing means. Fuel composition detection means for detecting the composition of fuel, rotation speed detection means for detecting the cranking rotation speed of the engine, based on detection signals output from the water temperature detection means, the fuel composition detection means, and the rotation speed detection means, respectively. Fuel supply amount control means for controlling the fuel supply amount by the main fuel supply means at engine startup, and the water temperature detection means and the fuel composition detection means at fuel supply by the main fuel supply means at engine startup. And configured to include a operation means for operating the auxiliary fuel supply means when the predetermined temperature or less and a given fuel composition based on the detection signal output.

[0007]

In this structure, based on the composition of the mixed fuel, the cooling water temperature of the engine and the cranking speed of the engine,
The fuel supply amount of the main fuel supply means is controlled and the driving of the auxiliary fuel supply means is controlled. Therefore, for example, even when a high-concentration alcohol fuel or the like is used as the mixed fuel, it is possible to reliably start at low temperature,
Since the fuel supply amount control of the main fuel supply means is controlled on the basis of the cranking rotation speed of the engine, the fuel supply quantity is optimized even when the starting rotation speed of the engine drops to a predetermined low rotation speed. As a result, there is no possibility of inducing irregular combustion, and the engine can be started.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In FIG. 2 showing the system configuration of one embodiment of the present invention, in addition to a fuel injection valve 3 as a main fuel supply means being provided for each cylinder in an intake passage 2 of an engine 1, it is also used as an auxiliary fuel supply means. An auxiliary fuel injection valve 4 for cold start, which is referred to as a cold start valve (CSV), is provided at the upstream collecting portion of the intake passage 2. The auxiliary fuel injection valve 4 is ON / OFF controlled.

The control unit 5 includes a starter switch 6, a water temperature sensor 7 as cooling water temperature detecting means for the engine 1, an electrode or capacitance type alcohol concentration sensor 8 as fuel composition detecting means, and a cranking rotation of the engine. The detection signals output from the rotation speed sensor 9 for detecting the number are input, and the control unit 5 controls the fuel injection valve 3 and the auxiliary fuel injection valve 4 based on these detection signals.

That is, the control unit 5 controls the fuel supply amount by the fuel injection valve 3 when the engine is started based on the detection signals output from the water temperature sensor 7, the alcohol concentration sensor 8 and the rotation speed sensor 9, respectively. And a predetermined alcohol temperature based on the detection signals output from the water temperature sensor 7 and the alcohol concentration sensor 8 during fuel supply by the fuel injection valve 3 at the time of engine startup. Each function of the operating means for operating the auxiliary fuel injection valve 4 at the time of the concentration is provided by software.

The function as such means will be described with reference to the flow chart of FIG. 3 showing the fuel supply control routine at the time of starting the engine. First, in step 1 (abbreviated as S1 in the figure, the same applies hereinafter), the starter switch 6 is turned on.
Whether or not the engine has started is determined. If the starter switch 6 is ON, the process proceeds to step 2, and if the starter switch 6 is OFF, the process returns. In step 2, it is determined whether the water temperature Tw read based on the detection signal output from the water temperature sensor 7 is -20 ° C or lower. If the water temperature Tw is -20 ° C or lower, the process proceeds to step 3, and if it is higher than 20 ° C, the process proceeds to step 4. In step 3, it is determined whether the alcohol concentration ALC read based on the detection signal output from the alcohol concentration sensor 8 is M60 or more. M
If it is 60 or more, the process proceeds to step 5, and if it is lower than M60, the process proceeds to step 4. In step 5, it is determined based on the detection signal output from the rotation speed sensor whether the cranking rotation speed N of the engine read is 100 rpm or less. If it is less than 100 rpm, proceed to step 6 and proceed to step 8. If it is higher than 100 rpm, proceed to step 7 and proceed to step 4.

Here, in step 6 and step 7,
Each of the auxiliary fuel injection valves 4 is turned on to turn on the auxiliary fuel injection valve 4.
To inject fuel from. In steps 8 and 4,
The starting fuel injection amount by the fuel injection valve 3 is determined based on the alcohol concentration, the water temperature, and the cranking rotation speed at that time, respectively. In this case, as shown in FIGS. 4 and 5, a map in which an injection pulse width for determining the fuel injection amount at startup for the high engine speed is set and stored in advance based on the alcohol concentration and the water temperature, and the alcohol is previously stored. A map in which the injection pulse width of the fuel injection valve that determines the fuel injection amount at startup is set and stored for low engine speed rotation based on the concentration and the water temperature is stored in the control unit 5, and in step 4, ,
The injection pulse width (msec) is searched and set from the map for high engine speed of FIG. 4 based on the alcohol concentration and water temperature at that time, and in step 8, from the map for low engine speed of FIG. The injection pulse width (msec) of the fuel injection valve is searched and set based on the alcohol concentration and the water temperature.

The maps are M0 (gasoline) and M8.
The injection pulse width corresponding to 5 is set and stored, and the injection pulse width corresponding to the alcohol concentration between M0 (gasoline) and M85 is the water temperature of M0 (gasoline) and M85 searched by the above map. The injection pulse width corresponding to is used to obtain it by interpolation calculation. It is not necessary to inject fuel from the auxiliary fuel injection valve 4 when it is determined in step 2 that the water temperature is higher than 20 ° C. and when it is determined in step 3 that the alcohol concentration ALC is lower than M60. Therefore, the auxiliary fuel injection valve 4
As described above, instead of turning ON, the process directly proceeds to step 4, and the injection pulse width is obtained by searching or computing from the map for high engine speed of FIG.

In the flowchart, step 6
The step 7 and the step 7 correspond to the operating means of the present invention, and the steps 4 and 8 correspond to the fuel supply amount controlling means of the present invention. According to this configuration, for example,
The engine cooling water temperature is -20 ° with an alcohol concentration of M60 or higher.
When the temperature is equal to or lower than C, the auxiliary fuel injection valve 4 is turned on so that the fuel injection by the auxiliary fuel injection valve 4 is performed, and the fuel injection valve 3 performs the fuel injection based on the alcohol concentration, the water temperature and the cranking rotation speed at that time. Since the injection amount is controlled, the alcohol concentration is M85 (85% alcohol,
Even when a high-concentration alcohol fuel such as gasoline (15%) (especially M60 or more) is used, the engine can be reliably started at a low temperature, especially at -25 ° C.

In particular, such a configuration has the following advantages. That is, for example, in the method of controlling the fuel injection amount by the fuel injection valve based on the alcohol concentration and the water temperature, when the cranking rotation speed drops below a certain rotation speed (for example, 100 rpm or less), the auxiliary fuel injection valve It has been found that, in combination with fuel injection according to No. 4, irregular combustion occurs which rather hinders the starting of the engine.

This is because the addition of the fuel supply amount by the fuel injection from the auxiliary fuel injection valve 4 makes it possible to start the engine within a few seconds even at -30 ° C at an engine speed higher than 100 rpm. , 100 r.pm or less, the fuel supply amount is too large and irregular combustion is induced. In this respect, according to the configuration of the above embodiment,
The fuel injection amount by the fuel injection valve 3 is controlled based on the alcohol concentration, the water temperature, and the cranking rotation speed.
Since the fuel injection pulse width is decided based on the map provided for high and low cranking speeds,
Even if the engine speed becomes 100 rpm or less, the situation in which the fuel supply amount is optimized and too large does not occur, there is no possibility of inducing irregular combustion, and the engine can be started.

By the way, in the above configuration, the time until starting is somewhat longer. Further, conventionally, as the alcohol concentration increases, the fuel injection amount from the fuel injection valve increases.
In this case, 5 to 6 times as much fuel was supplied as when only gasoline was used as the fuel, but in the above configuration, the supplied fuel amount is reduced to approximately the same as when only gasoline is used as the fuel.

As described above, the present invention has been described with reference to the specific embodiments, but the present invention is not limited to this, and is attached to the present invention by those skilled in the art. Without departing from the scope of the appended claims
It should be noted that various changes and modifications are possible.

[0019]

As described above, according to the present invention,
In an internal combustion engine that supplies a mixed fuel in which a plurality of types of fuel are mixed, a plurality of types are provided for each cylinder in the intake passage of the engine based on the composition of the mixed fuel, the cooling water temperature of the engine, and the cranking rotation speed of the engine. Since the fuel supply amount of the main fuel supply means for supplying the mixed fuel obtained by mixing the above fuel is controlled and the driving of the auxiliary fuel supply means provided at the upstream side of the intake passage is controlled, the high concentration Even when alcohol fuel is used, the engine can be reliably started at low temperatures, and the fuel supply amount is optimized even when the engine speed drops to a specified low speed. Therefore, there is no possibility that irregular combustion will be induced, and the possibility of starting the engine will be great.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a fuel supply device for starting an internal combustion engine according to the present invention.

FIG. 2 is a system diagram of an embodiment of the above fuel supply device.

FIG. 3 is a flowchart for explaining the operation of the above embodiment.

FIG. 4 is a map of fuel injection pulses for high engine speed in the above embodiment.

FIG. 5 is a map of fuel injection pulses for low engine speed in the above embodiment.

[Explanation of symbols]

 1 engine 2 intake passage 3 fuel injection valve 4 auxiliary fuel injection valve 5 control unit 6 starter switch 7 water temperature sensor 8 alcohol concentration sensor 9 rotation speed sensor

Claims (1)

[Claims] 1. A main fuel supply means, which is provided in each cylinder of an intake passage of an engine, for supplying a mixed fuel in which a plurality of types of fuel are mixed, and an upstream collecting portion of the intake passage. Auxiliary fuel supply means for supplying, a water temperature detection means for detecting the cooling water temperature of the engine, a fuel composition detection means for detecting the composition of the mixed fuel, a rotation speed detection means for detecting the cranking rotation speed of the engine, Fuel supply amount control means for controlling the fuel supply amount by the main fuel supply means at engine startup based on the detection signals respectively output from the water temperature detection means, fuel composition detection means, and rotation speed detection means, and at engine startup When the fuel is supplied by the main fuel supply means, the auxiliary fuel is supplied when the water temperature is lower than a predetermined water temperature and the fuel composition is a predetermined fuel composition based on the detection signals output from the water temperature detection means and the fuel composition detection means, respectively. Starting fuel supply system for an internal combustion engine, characterized in that it is configured to include an actuating means for actuating the means.