JPH03258943A - Fuel control method - Google Patents

Abstract

PURPOSE:To improve engine performance by computing a fuel supply quantity on the basis of an intake air quantity and a fuel pump flow quantity and each compensation factor of a storage means independently from a detected value of a blend ratio sensor when a blend ratio of the fuel is changed suddenly. CONSTITUTION:An ECU 14 of an engine 1, which uses the mixed fuel of gasoline and alcohol, computes a fuel supply quantity to be injected from an injector 21 with an intake air quantity detected by an air flow sensor 13 and a flow quantity of a fuel pump 25 on the basis of a compensation factor preset by a storage means 20 independently from a blend ratio detected by a blend ratio sensor 26 when a blend ratio of the fuel is changed suddenly. Consequently, even if a time lag exists in the blend ratio sensor 26, a blend ratio is compensated to a blend ratio close to the real blend ratio of the injection fuel to perform the fuel supply. Engine performance can be thereby improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel control method for an internal combustion engine that can use a fuel mixture of gasoline and alcohol.

(Conventional technology) In recent years, the development of alcohol engines that use methanol (methyl alcohol) as a low-pollution oil alternative fuel has been progressing. Switching is almost impossible, and it is expected that alcohol fuel and gasoline fuel will coexist at least temporarily at the time of switching.

In order to cope with this situation, it has been proposed to introduce a vehicle that can use either gasoline fuel or alcohol fuel, that is, a vehicle that has flexibility in the fuel used (hereinafter simply referred to as rFFV).

In such FFVs, in order to accurately control the engine, it is necessary to constantly detect the blend ratio, which is the mixture ratio of gasoline and alcohol, and to perform various controls such as adjusting the engine's ignition timing. become.

Therefore, there is also a fuel control device that measures the blend ratio of fuel supplied into the engine using a blend ratio sensor and performs control according to this blend ratio.

In this conventional fuel control device, a blend rate sensor is provided between a fuel pump and a delivery pipe in which a plurality of injectors corresponding to each cylinder are provided. In this device, when the fuel pump is driven by the electronic control unit (ECU), the fuel, which is a mixture of gasoline and alcohol, in the fuel tank is always kept at a constant flow rate per unit time.
It passes through the fuel pump and Tsuyue Strainer and is sent from the inline pipe into the delivery pipe.

Further, a portion of the fuel sent into the delivery pipe is supplied into each injector, and this fuel is injected from the injector into the corresponding combustion chamber under the control of the electronic control device. On the other hand, the remaining fuel that did not flow to each injector is returned to the fuel tank via a pipe on the return line side. The blend rate of the fuel sent into the delivery pipe is measured by a blend rate sensor, which is provided upstream and away from the delivery pipe where the injector is provided. In addition, all of the fuel taken into the injector within the delivery pipe is not injected all at once, but is injected sequentially, so it takes time until the fuel remaining in the injector is completely injected. That is, in Fig. 4, the blend ratio value detected by the blend ratio sensor is shown by a solid line (A), and the blend ratio value for the fuel actually injected by the injector is shown by a dotted line (0). , there is a difference between the blend rate detected by the blend rate sensor and the blend rate injected by the injector, that is, a lag time.In addition, this lag time is caused by Assuming that a constant flow rate of fuel is supplied per hour, as shown in Figure 5 (a) and (b), the fuel injection amount is determined as a function of the intake air amount, and if the flow rate by the fuel pump is small, the delay time It is not constant, as the delay time is large, and conversely, as it increases, the delay time decreases.The size of the flow rate by the fuel pump here refers to the size of the capacity of the built-in fuel pump itself, and the flow rate is not constant. Although the capacity cannot be adjusted exactly, the flow rate of the fuel pump changes depending on the battery voltage and manifold pressure, and its characteristics are shown in FIG. 5(C).

(Problems to be Solved by the Invention) As described above, in the conventional structure, fuel supply may not be performed properly due to the discrepancy between the blend ratio of the actual injected fuel and the blend ratio detected by the blend ratio sensor. It arises. As a result, there were problems such as the engine malfunctioning and engine performance deteriorating.

The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce the time difference that occurs between the blend ratio of fuel actually injected from the injector and the blend ratio of fuel in the portion measured by the blend ratio sensor. Adjusts the deviation in the blend ratio and supplies fuel based on the appropriate blend ratio.
An object of the present invention is to provide a fuel control method that can improve engine performance.

(Means for Solving the Problems) In order to achieve the above object, the fuel control method according to the present invention includes:
a fuel pump that supplies fuel containing a mixture of gasoline and alcohol into a fuel distribution path; an injector that is provided in the middle of the fuel distribution path and supplies the fuel into the cylinder; and an injector that is provided in the fuel distribution path and supplies the fuel into the cylinder a blend ratio sensor that detects the blend ratio of gasoline and alcohol in the fuel; an air flow sensor that detects the amount of air taken into the cylinder; and at least a correction coefficient map based on the fuel pump flow rate and the intake air amount. a storage means storing a correction coefficient map; and a control means for adjusting the fuel injection amount of the injector; The control means calculates the fuel supply amount of the injector from the intake air amount detected by the air flow sensor, the fuel pump flow rate, and each correction coefficient from the storage means, and calculates the amount of fuel supplied to the injector when the blend ratio changes. However, fuel supply control can be performed based on a value close to the blend ratio of fuel actually injected by the injector.

(Operation) According to this method, when the fuel blend ratio suddenly changes,
Regardless of the blend rate detected by the blend rate sensor,
The amount of fuel injected from the injector is calculated based on a correction coefficient determined in advance from the intake air amount detected by the air flow sensor and the fuel pump flow rate, so the blend rate sensor detects sudden changes in the blend rate. Even if there is a time lag between the blend ratio injected and the blend ratio of the fuel actually injected from the injector, the amount of fuel actually injected can be adjusted by adjusting the amount of fuel supplied by the injector. It is possible to correct and control the blend ratio to a state close to that of the blend ratio.

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings.

FIG. 1 is a schematic diagram of an engine control system to which a fuel control method according to the present invention is applied.

In the figure, in this device, a combustion chamber 2 of an engine 1 is communicated with an intake passage 3 and an exhaust passage 4 in a timely manner. Among these, the intake passage 3 is connected to the air cleaner 5. First intake pipe6. Expansion tube7.
The exhaust path 4 is formed by the second intake pipe 8, and the exhaust path 4 is formed by the first exhaust pipe 9. Catalyst 10° Second exhaust pipe 11. It is formed by a muffler 12.

More specifically, an air flow sensor 13 that outputs passing air amount information is disposed inside the air cleaner 5, and the output of this air flow sensor 13 is transmitted to an electronic control unit (ECU>1).
Connected to 4.

A throttle valve 15 is installed inside the expansion pipe 7, and a throttle position sensor 16 is provided opposite to the throttle valve 15. Moreover, the idle position of the throttle valve 15 is controlled by the electronic control device 14 via an idle speed control motor (ISC motor) 17.

A part of the second intake pipe 8 is provided with a water reservoir 18 opposite thereto, and a water temperature sensor 19 is attached thereto.

Furthermore, an injector 21 is attached to the end of the intake path 3. The injectors 21 are connected to a fuel pipe 23 via a delivery pipe 22, and are provided for each cylinder in the same number as the number of cylinders.

On the other hand, the fuel pipe 23 constituting the fuel system includes, in addition to the above-mentioned delivery pipe 22 provided in the middle of the fuel pipe 23, a fuel tank 24 in which fuel containing a mixture of gasoline and alcohol is stored. , a fuel pump 25 that sends the fuel in the fuel tank 24 to the delivery pipe 22 side, and a blend ratio sensor 26 that detects the mixing ratio of gasoline and alcohol in the fuel in the fuel pipe 23, that is, the blend ratio.
A fuel pressure regulator 27 for adjusting fuel pressure and the like are provided. Furthermore, in this fuel system, the value detected by the blend rate sensor 26 is input into the electronic control unit 14.

Then, when the engine is started, the fuel pump 25 is also driven by the electronic control device 14. Then, the fuel in the fuel tank 24 is delivered by the fuel pump 25 to the delivery pipe 22 side through the inline pipe 23a. Further, when passing through the blend rate sensor 26, the blend rate of this fuel is measured by the blend rate sensor 26. After that, the fuel flows into the delivery pipe 22, and part of the fuel is supplied into the combustion chamber 2 by the injector 21 controlled by the electronic control device 14, and the other part is supplied by the fuel pressure regulator 27. The fuel tank 24 passes through the return pipe 23b.
taken back inside.

Further, when fuel with a different blend ratio is supplied into the fuel pump 25 and the blend ratio suddenly changes by more than a certain value, this is detected by the blend ratio sensor 26. Then, the electronic control unit 14 learns the fuel injection amount determined by a function of the intake air amount and the fuel pump flow rate determined by the number between the battery voltage and the manifold pressure, and determines the fuel injection amount determined in advance as a function of the intake air amount and the fuel pump flow rate determined by the number between the battery voltage and the manifold pressure. The amount of fuel supplied from the injector 21 is calculated and adjusted based on the correction coefficient that has been set, and the amount of fuel supplied from the injector 21 is adjusted based on the amount of intake air that has been stored in the storage means 20 in advance based on the map shown in FIG. Correction coefficient K1
Correction coefficient KfP/pl due to AlR1 + fuel pump flow rate
, and the correction coefficient K (cyll) set for each cylinder is calculated and further multiplied by this value.

This adjustment control is executed by a program pre-installed in the electronic control unit ff1J, and an example of this program is shown in FIG.

That is, in the program shown in FIG. 2, the signal from the blend rate sensor 26 is used to monitor whether there has been a large change in the blend rate, that is, whether there has been a sudden change in the blend rate, using a signal from the blend rate sensor 26 while the engine is running (step 101). .

Then, if there is no sudden change in the blend ratio, step 10
Proceeding to step 7, the injector 21 and the like are controlled based on the previous blend ratio. On the other hand, if there is a large change in the blend rate, that is, if the blend rate suddenly changes, the value B of the blend rate is changed to step 102.
So the new blend ratio B. At the same time as being closed and taken in,
If the amount of fuel injected from the injector 21 is calculated and adjusted, in step 103, the current intake air amount is known from the signal from the air flow sensor 13, and the current amount is determined from the battery voltage, manifold pressure, etc. Next, the fuel injection base time is sequentially calculated and updated using the value obtained in step 103 and the value stored in the storage means 20 (steps 104, 105 and 106), where the fuel pump flow rate is determined. Injection time T
The calculation process is performed until the fuel injection base time fBINJl based on the blend rate determined by the blend rate sensor 26 becomes equal (step 107). When the injection base time TfBINJ+ becomes equal, the process returns to normal routine control according to the fuel injection time TflNJl until the next sudden change is detected. In addition, in the flow of Fig. 2, the symbol T
IA) is the fuel injection base time of the injector 21 when the blend ratio has been changed and is being adjusted, symbol T(4, F is the previous fuel injection base time updated during adjustment, symbol T+s+sJ, p+ is under adjustment) The fuel injection base time based on the blend rate of the previous blend rate sensor 26 updated in , the code TfBQINJl is the fuel injection base time when the blend rate suddenly changes, and the code K t F/P ) is the above correction based on the fuel pump flow rate In the coefficients and signs, ^IRI is the above correction coefficient based on the intake air amount, and the sign Kfcy11 is the above cylinder side correction coefficient.

Therefore, in this method, when the fuel blend ratio suddenly changes, the amount of fuel injected by the injector 21 is determined in advance in proportion to the intake air amount detected by the air flow sensor 13 and the fuel pump flow rate. By calculating and adjusting the correction coefficient based on +p/p++KtA+11+ and +eyz, the blend ratio detected by the blend ratio sensor 26 when changing the blend ratio and the blend ratio of the fuel actually injected from the injector 21 can be adjusted. Even if there is a time lag between them, this lag can be corrected by adjusting the amount of fuel supplied by the injector 21.

Although the present invention has been explained using the above embodiment, it is of course not limited to the structure of this embodiment, and various changes in design may be made without departing from the gist of the present invention. .

(Effects of the Invention) As explained above, according to the fuel control method according to the present invention, when the blend ratio of fuel suddenly changes, the fuel is injected from the injector regardless of the blend ratio detected by the blend ratio sensor. The supply amount is calculated based on a correction coefficient determined in advance from the intake air amount detected by the air flow sensor and the fuel pump flow rate, so when the blend rate suddenly changes, the blend rate detected by the blend rate sensor and the injector Even if there is a time lag between the time when the blend ratio of the fuel that is actually injected becomes equal, the blend ratio of the fuel that is actually injected will be close to the blend ratio of the fuel that is actually injected by adjusting the fuel supply I by the injector. Fuel supply can be performed with correction. As a result, engine performance etc. can be improved.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an engine control system to which the fuel control method according to the present invention is applied, and Fig. 2 shows an example of a control program used to adjust the fuel injection amount of an injector in the same engine control system. Flowchart, FIG. 3 is a diagram showing an example of a map for determining the adjustment amount of the fuel pump using the same fuel control method, FIG. 4 is a diagram for explaining problems with the conventional structure, and FIG. 5(a) r (b) - (c) are diagrams for explaining factors of time delay that occur in the conventional structure. 2... Combustion chamber, 13... Air flow sensor, 14
... Electronic control device (control means), 20 ... Storage means, 21 ... Injector, 22 Delivery vibe, 2
3...Fuel pipe, 24...Fuel tank, 25...Fuel pump, 26...Blend rate sensor. Figure 2 (a) (b) Shoot 1 on g￥4C4 (f-) 6f1; Li (large)

Claims (1)

[Claims] a fuel pump that supplies fuel containing a mixture of gasoline and alcohol into a fuel distribution path; an injector that is provided in the middle of the fuel distribution path and supplies the fuel into the cylinder; and an injector that is provided in the fuel distribution path and supplies the fuel into the cylinder a blend ratio sensor that detects the blend ratio of gasoline and alcohol in the fuel; an air flow sensor that detects the amount of air taken into the cylinder; and at least a correction coefficient map based on the fuel pump flow rate and the intake air amount. a storage means storing a correction coefficient map; and a control means for adjusting the fuel injection amount of the injector. A fuel control method characterized in that the amount of fuel supplied to the injector is calculated based on the intake air amount detected by the air flow sensor, the fuel pump flow rate, and each correction coefficient from the storage means without depending on the blend ratio. .