JPH0697016B2 - Engine fuel supply system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an engine fuel supply apparatus for supplying an alcohol-mixed fuel in a fuel tank to a fuel injection valve of an engine.

[Conventional technology]

Recently, alcohol blended gasoline, which is a mixture of alcohol in gasoline, is used in other countries. Since the octane number of course changes between genuine gasoline and alcohol blended gasoline, the fuel injection amount, ignition timing, etc. of the engine also differ. Therefore, looking at the fuel injection amount Ti when using genuine gasoline, Ti = T _P × α × α'C _OEF + T _S (1) where T _P : basic injection amount α: air-fuel ratio feedback correction coefficient α ′: Basic air-fuel ratio learning correction coefficient C _OEF : Various correction coefficients T _S : Battery voltage correction coefficient. At this time, the air-fuel ratio feedback correction coefficient α is corrected based on the oxygen concentration signal from the oxygen sensor, and the basic air-fuel ratio learning correction coefficient α ′ is learned and corrected from the basic injection amount T _P and the engine speed N. , Air-fuel ratio (weight ratio of air and fuel) A / F is controlled to be 15: 1.

In this way, the air-fuel ratio A / F of genuine gasoline is 15: 1, but the air-fuel ratio of alcohol-blended gasoline has the characteristics shown in Fig. 5, and when the alcohol concentration is 100%, the air-fuel ratio is
It is known to be 6: 1.

Therefore, when using alcohol blended gasoline,
From the equation (1), the fuel injection amount Ti ′ is calculated as Ti ′ = C _K × T _P × α × α ′ × C _OEF + T _S (2) where C _K is a constant determined by the alcohol concentration. .

Here, as the alcohol sensor for detecting the alcohol concentration in the alcohol-blended gasoline, a resistance-type alcohol sensor for detecting the alcohol concentration from the specific resistance value of gasoline and alcohol has been studied. In this resistance type alcohol sensor, as shown in FIG. 6, a pair of electrodes b and c are arranged opposite to each other with a predetermined dimension in the middle of a pipe a which is a flow path, and are interposed between the electrodes b and c. The resistance value decreases as the alcohol concentration of the alcohol-blended gasoline d increases, so that the electrodes b and c and the voltage detection resistance e are connected in series to the DC power supply f, and the output voltage derived from the voltage detection resistance e The alcohol concentration is detected from the change in E.

[Problems to be Solved by the Invention]

Incidentally, the alcohol-mixed gasoline supplied into the fuel tank may have its electric conductivity changed over time due to various factors such as metal ions and water content precipitated from the fuel tank and fuel system parts. Further, alcohol blended gasoline may have different alcohol concentrations depending on the gas station.

Therefore, when new alcohol-blended gasoline is filled in the fuel tank, the alcohol concentrations of the old alcohol-blended gasoline and the new alcohol-blended gasoline differ,
As shown in FIG. 7, the output voltage is different before and after refueling.

Therefore, immediately after refueling of new alcohol mixed gasoline, old alcohol mixed gasoline remains from the fuel pipe to the fuel injection valve, and the fuel injection valve injects old alcohol mixed gasoline for a while. Since the resistance type alcohol sensor detects the alcohol concentration of the new alcohol-blended gasoline, the fuel injection amount cannot be controlled properly and the engine startability immediately after refueling is poor.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an engine fuel supply device capable of improving engine startability by injecting a new alcohol mixed fuel by a fuel injection valve even immediately after refueling. The purpose is to provide.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the structure of the engine fuel supply device adopted by the present invention is a fuel tank for storing an alcohol-mixed fuel, and a refueling determination means for determining the end of refueling work for the fuel tank. A fuel pipe provided between the fuel tank and a fuel injection valve provided in the engine; an alcohol sensor provided in the middle of the fuel pipe to detect an alcohol concentration in the alcohol-mixed fuel; A fuel pump that supplies the alcohol-mixed fuel in the fuel tank to the fuel injection valve via a fuel pipe,
When the refueling determination means determines the end of refueling operation, the fuel pump is driven for a certain period of time, and the alcohol mixed fuel filled in the fuel tank is filled in the fuel pipe from the alcohol sensor to the fuel injection valve. It is composed of a filling means.

[Action]

With this configuration, the new fuel filling means quickly supplies the new alcohol mixed fuel from the fuel pipe to the fuel injection valve after the alcohol mixed fuel is supplied. Therefore, the fuel injected by the fuel injection valve at the time of the first engine start after refueling and the alcohol mixed fuel detected by the alcohol sensor provided in the middle of the fuel pipe are the same fuel, so that the appropriate fuel for the engine is used. The injection amount can be controlled.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 4.

In FIG. 1, reference numeral 1 denotes an automobile using alcohol-blended gasoline as a fuel, and a refueling lid 2 is hinged on the rear portion of a vehicle body 1A of the automobile 1 so as to be openable and closable.

Reference numeral 3 denotes a fuel supply system provided in the automobile 1. Four
Is a fuel tank that constitutes the fuel supply system 3 and stores alcohol-mixed gasoline inside. A fuel filler cap 5 is detachably provided on a fuel filler pipe 4A of the fuel tank 4. Further, 6 is a cap switch provided on the fuel filler pipe 4A, and the cap switch 6 is operated in association with opening and closing of the fuel filler cap 5 to detect the end of refueling work for the fuel tank 4. ing.

Reference numeral 7 denotes a fuel pipe, one end of which is connected to a discharge port side of a fuel pump 14 which will be described later, and the other end of which is connected to a fuel injection valve 9 provided in the engine 8 and an inflow side of a pressure regulator 10. A fuel filter 11 and an alcohol sensor 12 are provided on the way. On the other hand, the outflow side of the pressure regulator 10 is connected to the fuel tank 4 via a return pipe 13.

Here, the alcohol sensor 12 is for detecting the alcohol concentration in the alcohol mixed gasoline flowing through the fuel pipe 7. As the alcohol sensor 12, for example, a resistance type alcohol sensor shown in FIG. 6 is used. .

Further, 14 is a fuel pump provided in the fuel tank 4,
The fuel pump 14 supplies the alcohol mixed fuel to the fuel injection valve 9 through the fuel pipe 7. 15
Is a remaining amount sensor for detecting the remaining amount of the alcohol mixed gasoline stored in the fuel tank 4, and the remaining amount sensor 15 is attached to the fuel pump 14, for example.

Reference numeral 16 in the drawing denotes an intake manifold provided in the engine 8. An intake filter 17 is provided at the tip of the intake manifold 16 and an air flow meter 18 is provided midway.

Next, in FIG. 3, reference numeral 19 denotes an arithmetic unit that constitutes a fuel supply device, and the arithmetic unit 19 includes, for example, a processing circuit such as a CPU, ROM and RAM as a storage circuit, and an input / output circuit (none of which are shown). ) Etc. are configured as a microcomputer. The input side of the arithmetic unit 19 is connected to the engine switch 20, the remaining amount sensor 15, the cap switch 6, etc., and the output side is an alarm for warning that the fuel pump 14, the fuel injection valve 9 and the filler cap 5 have not been closed. It is connected to the vessel 21 etc. The program shown in FIG. 4 is stored in the ROM of the arithmetic unit 19.

The present embodiment is constructed in this way, and its operation will be described next with reference to FIG.

First, when the process starts, the engine switch 20 is read in step 1 and the engine switch 20 is read in step 2.
Whether it is ON or not is determined, and if it is OFF, the process proceeds to step 3 and the cap switch 6 is read. When it is determined in step 4 that the fuel filler cap 5 is closed, the vehicle 1 is merely stopped, and the process returns to step 1.

On the other hand, when the engine switch 20 is ON in step 2 described above, the cap switch 6 is read in step 5,
In step 6, it is determined whether the filler cap 5 is open.
If NO is determined in step 6, it means that the vehicle is traveling normally, so the process returns to step 1. On the other hand, in step 6, YE
When it is determined to be S, it is dangerous to refuel while the engine switch 20 is ON, so the engine 8 and the fuel pump 14 are stopped in step 7.

In step 4 described above, it is determined that the filler cap 5 is open,
When the engine 8 and the fuel pump 14 are stopped in step 7, the fuel tank 4 is refueled. And
In step 8, the output value of the remaining amount sensor 15 is read, and in step 9, it is determined whether or not the fuel has increased. When it is determined to be NO, the refueling cap 5 is opened, but since refueling is in preparation and actual refueling is not performed, the process returns to step 1. On the other hand, if YES is determined in step 9, it means that the refueling work has started. Therefore, the process proceeds to step 10, and the output value of the remaining amount sensor 15 is read, and it is determined in step 11 whether or not the increase in fuel has stopped. judge. If NO is determined, it means that refueling is being performed, and the process returns to step 10.

If YES is determined in step 11 described above, it means that the fuel increase has stopped and the refueling work has been completed. Therefore, the process proceeds to step 12, and the cap switch 6 is read,
In step 13, it is determined whether the filler cap 5 is closed. If NO is determined in step 13, step
Moving to 14, it is determined whether or not a fixed time t seconds, for example, 10 seconds, required to close the fuel filler cap 5 has elapsed after the refueling work is completed. Then, in step 14, the process returns to step 12 to read the cap switch 6 until the fixed time t seconds has elapsed. On the other hand, when the fixed time t seconds has elapsed in step 14, the alarm device 21 is activated in step 15 and an alarm is issued to prevent the automobile 1 from running with the filler cap 5 open, Return to step 12.

If YES is determined in step 13 described above,
In step 16, the fuel pump 14 is driven to supply new alcohol-mixed gasoline stored in the fuel tank 4 from the fuel pipe 7 to the fuel injection valve 9 side, and the return pipe 13 is returned. Then, in step 17, a predetermined time T required for filling the new fuel mixture with the new alcohol blended fuel from the fuel tank 4 to the fuel injection valve 9 in place of the old fuel.
It is determined whether seconds, for example 5 to 10 seconds, have elapsed. If NO is determined, the process returns to step 16 to continue driving the fuel pump 14, and if YES is determined, the fuel pump 14 is stopped and the process ends.

As described above, in the embodiment, it is determined from step 11 and step 13 whether or not the refueling work is completed, and if new alcohol-blended gasoline is supplied, the fuel pump 14 is driven in step 16. Fresh alcohol mixed fuel is supplied from the fuel pipe 7 to the fuel injection valve 9. by this,
The old alcohol-blended gasoline remaining in the fuel injection valve 9 through the fuel pipe 7 is mixed with the new alcohol-blended gasoline. Therefore, the alcohol-blended gasoline whose alcohol concentration is detected by the alcohol sensor 12 is the same as the fuel injected by the fuel injection valve 9, and the appropriate fuel injection amount can be controlled.

Further, in the embodiment, the cap switch 6 which is operated by the opening / closing operation of the filler cap 5 is provided, and the alarm device 21 is activated to issue an alarm when the opened state of the cap switch 6 continues for a certain time t seconds. , Fuel tank 4
It is possible to prevent fuel from leaking.

In the embodiment, step 11 and step 13 are specific examples of the refueling detection means, and step 16 is a specific example of the fresh fuel filling means, but the present invention is not limited to these specific examples.

In the embodiment, the cap switch 6 is provided on the fuel filler pipe 4A of the fuel tank 4. However, for example, the vehicle body 1A
It may be provided on the back surface of the refueling lid 2.

Further, the alcohol sensor 12 is not limited to the resistance type alcohol sensor, and the capacitance type alcohol sensor using the change in the dielectric constant of alcohol mixed gasoline, the alcohol concentration from the potential difference between the pair of electrodes immersed in the alcohol mixed gasoline, A so-called indirect sampling alcohol sensor for detection, or an optical alcohol sensor that utilizes a change in the amount of transmitted light may be used.

〔The invention's effect〕

The engine fuel supply device according to the present invention is as described above in detail, and it is determined by the refueling determination means whether or not the alcohol mixed fuel is supplied to the fuel tank, and when refueling is performed, the new fuel filling means is used. Since the fuel pump is driven for a certain period of time to fill the new fuel from the fuel pipe provided with the alcohol sensor to the fuel injection valve, the alcohol mixed fuel injected from the fuel injection valve to the engine first after refueling. And the alcohol-mixed fuel detected by the alcohol sensor are the same fuel. Therefore, when a new alcohol mixed fuel is supplied, the old alcohol mixed fuel does not remain from the alcohol sensor to the fuel injection valve, and the new fuel can control the appropriate fuel injection amount. The startability can be improved.

[Brief description of drawings]

1 to 4 relate to an embodiment of the present invention, FIG. 1 is an external view of an automobile using alcohol-blended gasoline as fuel, FIG. 2 is an overall configuration diagram showing a fuel supply system to an engine, and FIG. FIG. 4 is a block diagram showing a circuit configuration of an embodiment, fourth.
FIG. 5 is a flow chart showing the filling processing operation of alcohol-blended gasoline, FIGS. 5 to 7 are related to the prior art, FIG. 5 is a diagram showing the relationship between alcohol concentration and air-fuel ratio, and FIG. 6 is resistance type alcohol. Configuration diagram showing a specific configuration of the sensor, No. 7
The figure is a diagram showing changes in output voltage before and after refueling when fuels with different alcohol concentrations are refueled. 4 ... Fuel tank, 5 ... Fuel cap, 7 ... Fuel piping, 9 ... Fuel injection valve, 14 ... Fuel pump, 15 ... Remaining amount sensor.

Claims (1)

[Claims] 1. A fuel tank for storing an alcohol-mixed fuel, a fueling judging means for judging the completion of a fueling operation for the fuel tank, and a fuel tank arranged between the fuel tank and a fuel injection valve provided in an engine. A fuel pipe provided, an alcohol sensor provided in the middle of the fuel pipe for detecting an alcohol concentration in the alcohol mixed fuel, and an alcohol mixed fuel in the fuel tank through the fuel pipe to feed the alcohol mixed fuel to the fuel injection valve. And a fuel pump that supplies fuel to the fuel tank and drives the fuel pump for a certain period of time when the refueling determination means determines the end of the refueling operation, and applies the alcohol mixed fuel filled in the fuel tank from the alcohol sensor to the fuel injection valve. An engine fuel supply device comprising a new fuel filling means for filling a pipe.