JPH0443833A - Fuel supply device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve startability, especially high temperature re-startability and operability by correcting a fuel supply quantity based on fuel composition, fuel temperature, and fuel residence characteristic of a fuel supply means. CONSTITUTION:A fuel temperature detecting means E to detect temperature of mixed fuel, a vapor correcting quantity setting means F to set a vapor correcting quantity based on the detected mixed fuel temperature and fuel composition, a characteristic correcting quantity setting means G to set a characteristic correcting quantity of a fuel supply means C based on a fuel residence characteristic of the means, and a correcting means H to correct a fuel supply quantity based on a set vapor correcting quantity and characteristic correcting quantity, are provided. Thus, the fuel supply quantity is corrected based on the composition of mixed fuel and the fuel temperature, and set in optimum regardless of a vapor generating quantity. Further, the fuel supply quantity is corrected based on the fuel remaining characteristic of the fuel supply means, and optimum fuel supply quantity is insured regardless of the sort of the fuel supply means. Hereby, startability and operability are improved.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a fuel supply system for an internal combustion engine that uses a mixed fuel of a plurality of fuels such as methanol and other fuels such as gasoline, and particularly relates to Regarding technology for improving startability.

<Prior art> Conventional example of this type of fuel supply device for an internal combustion engine (4?
2-243937)) are as follows.

That is, after calculating the basic injection amount from, for example, the engine rotational speed and the intake air flow rate (engine load), the basic injection amount is corrected based on the cooling water temperature, alcohol concentration, etc. to calculate the fuel injection amount. Then, an injection pulse signal corresponding to the calculated fuel injection amount is output to the fuel injection valve to supply fuel to the engine.

Further, at the time of starting (during cranking), in order to improve startability, a starting injection amount is calculated separately from the fuel injection amount calculation, and fuel is supplied to the engine.

<Problems to be Solved by the Invention> By the way, in alcohol mixed fuel, the vapor pressure of the fuel changes depending on the mixed fuel concentration, so the amount of vapor generated also changes depending on the fuel concentration, so starting performance and drivability may vary depending on the fuel concentration. There is a problem in that it makes things worse. In particular, when the mixed fuel is at a high temperature, the amount of vapor generated increases, so restartability and drivability at high temperatures are adversely affected.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel supply device for an internal combustion engine that can improve startability and drivability.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention supplies a mixed fuel in which a plurality of types of fuel are mixed to an engine, and detects the composition of the mixed fuel. a fuel composition detecting means A for detecting the fuel composition; a fuel supply amount setting means B for setting the fuel supply amount based on the detected fuel composition; and a drive control means for driving and controlling the fuel supply means C based on the set fuel supply amount. Rito,
a fuel temperature detection means E for detecting the temperature of the mixed fuel or a temperature related thereto, and a steam correction amount setting means for setting a steam correction amount based on the detected mixed fuel temperature and fuel composition. F, characteristic correction amount setting means G for setting the characteristic correction amount of the fuel supply means A based on the fuel retention characteristics of the fuel supply means A, and A correction means H for correcting the fuel supply amount is provided.

<Operation> In this way, by correcting the fuel supply amount based on the composition of the mixed fuel and the fuel temperature, the fuel supply amount is optimally set regardless of the amount of vapor generated, improving startability and drivability. I did it like that. In addition, by correcting the fuel supply amount based on the fuel retention characteristics of the fuel supply means, an optimal fuel supply amount can be ensured regardless of the type of fuel supply means,
This also improves startability and drivability.

<Example> An example of the present invention will be described below based on FIGS. 2 to 14.

In FIG. 2, the microcomputer 1 receives an intake air flow rate signal from an air flow meter 2, a reference signal (corresponding to the engine rotation speed) and a position signal from a crank angle sensor 3, and an air flow signal based on the oxygen concentration in the exhaust gas. An oxygen concentration signal from an oxygen sensor 4 that detects the fuel ratio, an alcohol concentration signal from an alcohol concentration sensor 5 as a fuel composition detection means installed in a fuel supply passage (not shown), and a cooling signal from a water temperature sensor 6. A water temperature signal and a fuel temperature signal from a fuel temperature sensor 7 serving as fuel temperature detection means are input.

The microcomputer 1 has an l10IA and a CPUI.
A fuel injection valve 8 is configured to include a fuel injection valve B, a ROMIC, and a RAMI D, and calculates a fuel injection amount based on signals from the various sensors, and serves as a fuel supply means installed in the intake system of the engine. Outputs an injection pulse signal to.

Here, the microcomputer 1 constitutes a fuel supply amount setting means, a drive control means, a steam correction amount setting means, a characteristic correction amount setting means, and a correction means.

Next, the operation will be explained according to the flowchart shown in FIG.

Sl reads various signals from the air flow meter 2, crank angle sensor 3, etc.

In S2, a basic injection amount T, (=KQ/; K is a constant) is calculated from the detected intake air flow rate Q and engine rotational speed N.

In S3, the alcohol correction coefficient ALC is searched from the map based on the alcohol concentration detected by the alcohol concentration sensor 5. As shown in FIG. 4, this alcohol correction coefficient ALC is set to increase approximately linearly as the alcohol concentration increases.

In S4, the valve characteristic correction coefficient KINJ is searched from the map based on the cooling water temperature detected by the water temperature sensor 6. The valve characteristic correction coefficient KINJ is, as shown in Fig. 5,
In the top-feed type fuel injection valve described below, it is maintained at a substantially constant value regardless of the cooling water temperature in the cooling water temperature range below a predetermined value (approximately 80°C), and is cooled in the cooling water temperature range exceeding the predetermined value. It is set to increase as the water temperature rises.

Further, as shown in FIG. 5, the valve characteristic correction coefficient KINJ is maintained at a substantially constant value in a bottom feed type fuel injection valve, which will be described later, regardless of the cooling water temperature. Here, since the top-feed type and bottom-feed type are determined depending on the engine specifications, either one of the valve characteristic correction coefficients may be stored in the map. Note that the valve characteristic correction coefficient may be set in accordance with the fuel temperature.

In S5, the vapor pressure correction coefficient KRVP is searched from the map based on the detected alcohol concentration and fuel concentration. As shown in Figure 6, the vapor pressure correction coefficient KRVP is set to increase as the alcohol concentration increases in the low alcohol concentration range, and decrease as the alcohol concentration increases in the higher alcohol concentration range. .

Further, as shown in FIG. 6, the vapor pressure correction coefficient KRVP increases as the fuel temperature increases in the alcohol concentration range below a predetermined value (approximately M80), and increases as the fuel temperature increases in the alcohol concentration range exceeding the predetermined value. It is set to decrease as the value increases. Note that after determining the vapor pressure/correction coefficient based on the alcohol concentration, the coefficient may be corrected based on the fuel temperature, or vice versa.

In S6, it is determined whether or not it is starting (cranking, etc.),
When the answer is YES, the process advances to S7, and when the answer is No, the process advances to S14.

In S7, the starting basic injection amount TC3T is searched from the map based on the detected cooling water temperature.

As shown in FIG. 7, the starting basic injection amount TCST is set to decrease as the cooling water temperature increases.

In S8, based on the detected engine rotation speed, the rotation correction coefficient TC3N is set to 1 when the engine rotation speed during cranking is less than a predetermined value, and is set to 1 when the engine rotation speed during cranking is above a predetermined value, as shown in FIG. is set to decrease as the engine rotation speed increases.

In S9, the starting injection amount TTST is calculated using the following equation.

TTST=TC3TXTC3NXALCXTKC3xK
INJxKRVP TKC3 is a time correction coefficient during cranking (
It is maintained at a constant value until a predetermined period of time has elapsed since the start of cranking (while the starter motor is in operation) or after the start of cranking, and then it is set to gradually decrease to zero as time elapses.

In SIO, the starting injection amount TST is calculated using the following equation.

T S T = T p X COE F X A L
CX a X 1.3 +T.

C0EF is various correction coefficients, expressed as (10 water temperature increase correction coefficient + air-fuel ratio correction coefficient + starting and post-start increase correction coefficient + post-idling increase correction coefficient + acceleration reduction correction coefficient + high water temperature increase correction coefficient) be done.

α is an air-fuel ratio feedback correction coefficient based on the detection signal of the oxygen sensor 4, and T is a voltage correction amount based on the battery voltage.

Sll compares the starting injection amount TTST and TST, and when TTST≧TST, proceeds to -312 and sets TTST.
<TST, the process advances to S13.

In S12, the starting injection amount TTST is selected.

In S13, the starting injection amount TST is selected.

At step 314, a starting and post-starting basic increase correction coefficient KASB is searched from the map based on the detected cooling water temperature. As shown in FIG. 9, KASB is set to decrease as the cooling water temperature increases.

In S15, a starting and post-starting increase correction coefficient KAS is calculated using the following equation.

KAS=KASBXKANJXKRVPThe above KAS is
From the end of cranking, it is corrected to gradually decrease to zero at predetermined times or every predetermined rotation.

In S16, the fuel injection amount T1 is calculated using the following equation.

T,=T,×C0EFxALC×α+T.

KAS is included in various correction coefficients C0FF.

In this way, an injection pulse signal corresponding to the selected startup injection amount or fuel injection amount T is output to the fuel injection valve 8, and fuel is supplied to the engine.

As explained above, since the starting injection amount and the post-starting fuel injection amount are calculated based on the vapor pressure correction coefficient KRVP obtained from the alcohol concentration and fuel concentration, the injection amount depends on the alcohol concentration and fuel temperature. Even if the amount of vapor generated changes due to changes in the amount of vapor generated, the starting injection amount and fuel injection amount can be set optimally regardless of the amount of vapor generated, which improves startability and drivability, and significantly improves restartability especially at high temperatures. can.

In addition, since the starting injection amount and fuel injection amount are corrected based on the fuel feed type to the fuel injection valve, the optimum starting injection amount and fuel injection amount can be secured regardless of the feed type. This also improves startability and driveability, and in particular, greatly improves high-temperature restartability.

This will be explained in detail based on FIGS. 10 to 14. As shown in FIG. Fuel is supplied and injected from the nozzle hole 10C at the lower end. Further, as shown in FIG. 11, the bottom-feed solid fuel injection valve 11 supplies fuel from a fuel supply passage 11B to a fuel supply port 11A on the side of the injection valve body, injects fuel from a nozzle hole IC, and injects surplus fuel. is returned to the return passage 11D from the upper end.

In addition, as shown in FIG. 12, the new bottom-feed type fuel injection valve 12 has an injection valve main body interposed in a fuel supply passage 12A, and fuel is introduced from a fuel supply port 12B on the side and a nozzle hole at the lower end. It is injected from 12C.

Furthermore, as shown in FIG. 13, the new bottom-feed improved fuel injection valve 13 introduces fuel from the lower fuel supply port 13A in addition to the new bottom-feed type, and
It is injected from 3B.

Among these feed types, the top feed type has the longest time for fuel to stay in the injector body (the bottom feed type, the new cylinder feed type, and the new bottom feed improved type have the longest fuel retention time). The residence time of the fuel is shortened.Then, the residence time of the fuel is long (indeed, vapor is likely to be generated within the injector body), and the restart time corresponds to the residence time of the top-feed type as shown in Figure 14. The longer it is, the longer it is.

Therefore, since the starting injection amount and fuel injection amount are corrected according to the feed type, starting performance and drivability can be improved.

It should be noted that a fuel temperature sensor may be provided to determine the steam correction coefficient, or the steam correction coefficient may be determined from the cooling water temperature related to the fuel temperature.

<Effects of the Invention> As explained above, the present invention corrects the fuel supply amount based on the fuel composition, fuel temperature, and fuel retention characteristics of the fuel supply means, regardless of the type of fuel supply means. Since an optimum fuel supply amount can be secured, startability, especially high temperature restartability and drivability, can be improved.

[Brief explanation of the drawing]

Fig. 1 is a claim correspondence diagram of the present invention, Fig. 2 is a configuration diagram showing an embodiment of the present invention, Fig. 3 is a flowchart of the same as above,
Figures 4 to 9 are diagrams for explaining the same effect as above;
0 to 13 are diagrams for explaining the types of fuel injection valves, and FIG. 14 is a characteristic diagram of the same. 1...Microcomputer 2...Air flow meter 3...Crank angle sensor 5...Alcohol concentration sensor 6...Water temperature sensor 7...
Fuel temperature sensor 8... Fuel temperature sensor patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio Sasashima Figure 2 Q Figure 7; 10C Figure 11 +1c

Claims (1)

[Claims] A fuel composition detecting means for detecting the composition of the mixed fuel, and a fuel supply for setting a fuel supply amount based on the detected fuel composition, which supplies a mixed fuel made by mixing a plurality of types of fuel to the engine. In a fuel supply system for an internal combustion engine, the temperature of the mixed fuel or a temperature related thereto is detected in a fuel supply device for an internal combustion engine, comprising a quantity setting means and a drive control means for driving and controlling the fuel supply means based on the set fuel supply quantity. fuel temperature detection means, steam correction amount setting means for setting a steam correction amount based on the detected mixed fuel temperature and fuel composition, and characteristic correction of the fuel supply means based on the fuel retention characteristics of the fuel supply means. A fuel supply device for an internal combustion engine, comprising: a characteristic correction amount setting means for setting the amount; and a correction means for correcting the fuel supply amount based on the set steam correction amount and the characteristic correction amount. .