JPS61218741A - Controller for feed of alcohol-mixed fuel for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the generation of misfire and deterioration of emission by controlling the quantity of feed of fuel according to the concentration of alcohol in fuel during acceleration and deceleration, thus preventing the formation of excessively thick or lean mixed gas. CONSTITUTION:In an engine into which alcohol-mixed fuel is supplied, a concentration detecting means 30 for detecting the concentration of alcohol in fuel and an acceleration detecting means 31 are installed. When acceleration state is detected, a fuel increasing signal is sent into a fuel feeding apparatus from a fuel increasing means 32 in proportion to the concentration of alcohol. Therefore, the state where the hardly vaporized alcohol-mixed fuel adheres onto the inner wall of an intake passage in acceleration and the mixed gas is made lean, and misfire is generated can be prevented. Similarly, in deceleration, fuel is reduced in proportion to the concentration of alcohol, and the deterioration of emission can be prevented by making the mixed gas thick.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an alcohol mixed fuel supply control device for an internal combustion engine.

[Conventional technology]

The stoichiometric air-fuel ratio when only gasoline is used is about 14.6, but the stoichiometric air-fuel ratio when only alcohol is used is about half that when only gasoline is used. Therefore, the stoichiometric air-fuel ratio when using an alcohol-mixed fuel made by mixing alcohol with gasoline is smaller than the stoichiometric air-fuel ratio when using only gasoline, and this stoichiometric air-fuel ratio changes depending on the alcohol concentration in the gasoline. Therefore, if an attempt is made to supply a mixture at a stoichiometric air-fuel ratio into an engine cylinder using alcohol mixed fuel, the amount of fuel supplied must be controlled in accordance with the alcohol concentration. For this purpose, an internal combustion engine is known that detects the alcohol concentration and controls the fuel injection amount according to the alcohol concentration so that the air-fuel ratio of the mixed supply supplied into the engine cylinder becomes the stoichiometric air-fuel ratio. Publication No. 58-28557).

On the other hand, using alcohol mixed fuel, a 0□ sensor whose output voltage changes stepwise at the stoichiometric air-fuel ratio is installed in the engine exhaust passage, and the air-fuel mixture supplied into the engine cylinder is determined based on the output signal of the 0□ sensor. An internal combustion engine in which the fuel ratio is made to match the stoichiometric air-fuel ratio is known (Japanese Unexamined Patent Application Publication No. 56
-98540 or JP-A-56-104131).

[Problem that the invention seeks to solve]

However, when alcohol mixed fuel is used, it is not only the stoichiometric air-fuel ratio that changes, but also the amount of fuel that is required to be approximately twice that of when only gasoline is used.Moreover, the higher the mixing ratio of alcohol, the more vaporized the fuel becomes. becomes worse. Therefore, when using alcohol mixed fuel, it is not possible to ensure good vehicle drivability unless these considerations are taken into consideration. That is, when alcohol-mixed fuel is used, a large amount of fuel must be supplied as described above, and furthermore, since vaporization deteriorates, the amount of fuel that adheres to the inner wall surface of the intake passage increases during acceleration operation. The amount of adhering fuel increases as the alcohol mixing ratio increases. Therefore, even if the amount of fuel is increased by a certain amount, such as when only conventional gasoline is used during acceleration operation, if the alcohol mixture ratio is large, the air-fuel mixture taken into the engine cylinder will become too lean, resulting in a misfire. Conversely, if the alcohol mixing ratio is small, the air-fuel mixture supplied into the engine cylinder will become too rich, leading to deterioration in emissions and fuel consumption. On the other hand, when the vehicle decelerates, a large negative pressure is generated and the fuel adhering to the inner wall of the intake passage vaporizes in a short period of time. If the fuel supply is not slightly reduced, the air-fuel mixture supplied into the engine cylinders will become too lean or too rich, causing similar problems.

[Means for solving problems]

In order to solve the above problems, the present invention provides an internal combustion engine in which alcohol mixed fuel is supplied into the engine intake passage 5 as shown in the block diagram of the invention in FIG. A concentration detecting means 30 for detecting, an acceleration detecting means 31 for detecting an accelerated driving state, and a fuel increase for increasing the amount of fuel in proportion to the alcohol concentration during accelerated driving based on the detection results of the concentration detecting means 30 and the acceleration detecting means 31. means 32.

Furthermore, in order to solve the above-mentioned problems, according to the present invention, in an internal combustion engine in which alcohol-mixed fuel is supplied into the engine intake passage 5, as shown in the configuration diagram of the invention in FIG.
Concentration detection means 3 for detecting alcohol concentration in gasoline
0, a deceleration detecting means 33 for detecting a decelerating driving state, and a fuel reducing means 34 for reducing the amount of fuel in proportion to the alcohol concentration during decelerating driving based on the detection results of the concentration detecting means 30 and the decelerating detecting means 33. are doing.

〔Example〕

Referring to Figure 3, 1 is the engine body, 2 is the piston, and 3
is a combustion chamber, 4 is an intake valve, 5 is an intake passage, 6 is an intake passage 5
7 is a throttle valve, 8 is an exhaust valve, 9 is an exhaust passage, and IO is a fuel injection valve arranged in the intake passage 5. Fuel injection valve IO is fuel supply pipe 11
It is connected to a fuel tank 13 via a fuel supply pump 12, and gasoline containing alcohol, ie, alcohol mixed fuel, is stored in the fuel tank 13. An alcohol concentration detector 14 for detecting the alcohol concentration in the alcohol mixed fuel is disposed within the fuel supply pipe ll,
A negative pressure sensor 15 is disposed within the surge tank 6 and generates an output voltage proportional to the negative pressure generated within the surge tank 6. These alcohol concentration detector 14 and negative pressure sensor 15 are connected to an electronic control unit 20.

The electronic control unit 20 consists of a digital computer with ROMs interconnected by a bidirectional bus 21.
(read-only memory) 22, RAM (random access memory) 23, CPU (microphone processor) 2
4, an input port 25 and an output port 26.

Furthermore, the electronic unit 20 has a multiplexer function.
A D converter 27 is provided, and this AD converter 27 is connected to the input port 25. The alcohol concentration detector 14 and the negative pressure sensor 15 are connected to the input terminal of the AD converter 270, and the output signals of the alcohol concentration detector 14 and the negative pressure sensor 15 are sequentially input to the input port 25 via the AD converter 27. be done. Furthermore, a rotation speed sensor 16 is connected to the input port 25, which generates an output pulse every time the engine crankshaft rotates by a predetermined crank angle. Further, the output port 26 is connected to the fuel injection valve 10 via a drive circuit 28. The alcohol concentration detector 14 detects the alcohol concentration in the fuel injected from the fuel injection valve 10 and generates an output voltage proportional to the alcohol concentration.

Next, the fuel supply method according to the present invention will be explained with reference to the flowchart shown in FIG.

Referring to FIG. 7, first, in step 102, the output signal of the rotation speed sensor 16 representing the engine rotation speed NE is taken in to calculate the engine rotation speed NE, and then in step 10
At step 4, the output signal of the negative pressure sensor 15 representing the intake pipe negative pressure P is taken in.Then, at step 106, the ROM is
NE, P and basic injection amount TAυ are stored in advance in the form of a map in 22. The basic injection amount TA[Ia is determined from the relationship with . Next, in step 10B, the intake pipe negative pressure P0 detected in the previous interrupt cycle is read from a predetermined address in the RAM 23. Next, in step 110, the previous intake pipe negative pressure P0 is subtracted from the current intake pipe negative pressure P to find the amount of change in the negative pressure P. Next, in step 112, it is determined whether ΔP is larger than a constant value a.

In the case of Δpea, it is determined that the engine is not in an accelerating operation state, and after the acceleration increase α is set to O in step 124, the fuel injection amount TAU is determined in step 122. In this case, no accelerated increase is performed.

On the other hand, when it is determined in step 112 that ΔPea is present, that is, during acceleration operation, the process proceeds to step 114, where the acceleration increase amount α is calculated. Next, in step 116, the output signal of the alcohol concentration detector 14 representing the alcohol concentration F is taken in, and then in step 118, a correction coefficient K is determined from the relationship shown in FIG. 5, which is previously stored in the ROM 22. As can be seen from FIG. 5, this correction coefficient is 1.0 when the alcohol concentration F is 0%, and increases as the alcohol concentration F increases.

Next, in step 120, the acceleration increase α is multiplied by K.
The result is defined as acceleration increase α. Next, in step 122, the fuel injection amount TAU is determined by adding the acceleration increase α to the basic injection amount TAU6. Therefore, the injection amount TA
It can be seen that U increases as the alcohol concentration F increases. FIG. 4 shows the relationship between the fuel adhesion rate Q to the inner wall surface of the intake passage and the alcohol concentration F. It can be seen that the adhesion rate Q increases as the alcohol concentration F increases.

However, in the present invention, since the injection amount TAU is increased as the alcohol concentration F increases during acceleration operation, the air-fuel ratio of the air-fuel mixture supplied into the engine cylinders can be maintained constant, and in this way, the air-fuel mixture is prevented from becoming excessive. It can prevent it from becoming too dark or too light.

FIG. 6 shows the correction coefficient K when the present invention is applied during deceleration operation. In this case, the correction coefficient gradually decreases from 1.0 as the alcohol concentration F increases, and therefore, as the alcohol concentration F increases, the fuel injection amount T
It can be seen that AU decreases. In this case, it is necessary to set P and -P to ΔP in step 110.

If deceleration operation is started when the adhesion rate Q is large, the amount of vaporized fuel will increase. However, in the present invention, since the injection amount TAU is decreased as the alcohol concentration F increases, the air-fuel ratio of the air-fuel mixture supplied into the engine cylinder can be maintained constant, and in this way, the air-fuel mixture becomes overrich. This can prevent it from becoming too thin or too thin.

〔Effect of the invention〕

By controlling the amount of fuel supplied according to the alcohol concentration during acceleration and deceleration, it is possible to prevent the mixture supplied into the engine cylinder from becoming too rich or too lean, thus preventing misfires. This can prevent emissions and fuel consumption from worsening.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the present invention, Fig. 2 is a block diagram of the present invention,
Fig. 3 is an overall diagram of the internal combustion engine, Fig. 4 is a diagram showing the wall surface adhesion rate Q of fuel, Fig. 5 is a diagram showing the relationship between the correction coefficient during acceleration operation and the alcohol concentration F, and Fig. 6 is a diagram showing the relationship between the correction coefficient during acceleration operation and the alcohol concentration F. The figure is a diagram showing the relationship between the correction coefficient and the alcohol concentration F during deceleration operation, and FIG. 7 is a flowchart for executing fuel injection control. 5...Intake passage, 9...Exhaust passage, 10...
Fuel injection valve, 14... Alcohol concentration detector, 20.
...Electronic control unit. Fig. 1 Fig. 2 Fig. 3 Fig. 5...Intake passage 9...Exhaust passage 1o...Fuel injection valve 1481. Alcohol concentration detector Figure 7

Claims (1)

[Scope of Claims] 1. In an internal combustion engine configured to supply alcohol-mixed fuel into the engine intake passage, a concentration detection means for detecting the alcohol concentration in gasoline, an acceleration detection means for detecting an accelerated driving state, An alcohol mixed fuel supply control device for an internal combustion engine, comprising a fuel increasing means for increasing the amount of fuel in proportion to the alcohol concentration during acceleration operation based on the detection results of the concentration detecting means and the acceleration detecting means. 2. In an internal combustion engine configured to supply alcohol-mixed fuel into the engine intake passage, the concentration detection means detects the alcohol concentration in gasoline, the deceleration detection means detects a deceleration driving state, and the concentration detection means and deceleration An alcohol mixed fuel supply control device for an internal combustion engine, comprising a fuel reduction means for reducing the amount of fuel in proportion to the alcohol concentration during deceleration operation based on the detection result of the detection means.