JPH04321736A - Fuel supply device for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a fuel supply device of which fuel infection quantity is smoothly controlled especially in case of changing concentration of different component due to oil supply and the like, in an internal combustion engine using fuel mixed with different component such as alcohol. CONSTITUTION:Fuel containing alcohol in a fuel tank 11 is supplied to fuel infection valves 141-144 with a fuel pump 12 through a fuel passage 13. A concentration sensor 17 to detect alcohol concentration in fuel is provided on the way of the fuel passage 13, the detected signal from the sensor 17 is supplied to a control circuit 15, and the fuel injection valves 141-144 are driven with the control circuit 15. In the control circuit 15, change of alcohol concentration in fuel is detected, and a delay time corresponding to a time which old fuel stored in the part of the fuel injection valves has been injected from generation of change of alcohol concentration in fuel is computed. After the lapse of the delay time from the time point of concentration change, the factor of correction corresponding to alcohol concentration of the new fuel is set, and fuel injection is controlled.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for an internal combustion engine using fuel mixed with a different component such as alcohol.

0002

2. Description of the Related Art It has been considered to mix other components such as alcohol into ordinary gasoline as a fuel for internal combustion engines. When using fuel mixed with such different components, it is necessary to perform fuel supply control corresponding to the mixing ratio of the different components.

[0003]Also, the amount of different components mixed into the fuel used is basically set constant, and the concentration of different components in the fuel used is kept constant. Substantially, for example, when new fuel is supplied to a fuel tank, the different component concentrations of the fuel supplied to the fuel injection valve section change depending on the supplied fuel. Therefore, when executing fuel injection amount control, it is desirable to calculate the fuel injection amount based on the different component concentrations of the fuel actually injected from the fuel injection valve.

In conventional internal combustion engines that use fuel mixed with different components such as alcohol, the fuel pumped from the fuel tank by the fuel pump is guided to the fuel filter section through the fuel passage. Further, the fuel that has passed through this filter section is injected from the injection valve.

In this case, an alcohol concentration sensor is installed in the fuel passage, and this concentration sensor section detects the concentration of alcohol mixed in the fuel, and also measures the temperature of this fuel, and uses this alcohol concentration information and the temperature of the fuel. Information is provided to the control circuit. In this control circuit, based on the input alcohol concentration and fuel temperature, the amount of fuel injected from the fuel injection valve is corrected so that the air-fuel ratio is optimized, and a drive signal is sent to the fuel injection valve. We are trying to supply it.

However, in the fuel supply device configured in this manner, the alcohol concentration sensor is installed in the middle of the fuel passage. Therefore, when the alcohol concentration in the fuel changes due to refueling into the fuel tank, the following problems occur.

[0007] When the alcohol concentration in the fuel tank changes due to refueling, and fuel with a different alcohol concentration reaches the alcohol concentration sensor section, alcohol concentration information of the new fuel is supplied to the control circuit, and based on this information, The fuel injection valve is driven by the corrected drive signal.

However, since there is an additional fuel passage between the alcohol concentration sensor and the fuel injection valve, and there is also old fuel that remains in the fuel injection valve, fuel with a different alcohol concentration may come from the fuel injection valve. Before being sprayed,
There is a predetermined time delay after the alcohol concentration sensor detects a change in alcohol concentration.

That is, if a change in alcohol concentration is detected by an alcohol concentration sensor and the drive signal of the fuel injection valve is corrected and controlled in accordance with the detected alcohol concentration, the An inconvenience occurs in that the old fuel injection control is executed based on the newly detected alcohol concentration. Therefore, an optimum air-fuel ratio cannot be ensured, leading to deterioration in fuel efficiency, stalling, emission characteristics, and drivability.

0010

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and it is an object of the present invention to provide a fuel that responds to the change in concentration of different components such as alcohol contained in the fuel. It is an object of the present invention to provide a fuel supply system for an internal combustion engine in which injection control is executed, responsiveness is good, and optimal air-fuel ratio control can be executed.

[0011]

[Means for Solving the Problems] In the fuel supply device for an internal combustion engine according to the present invention, a foreign component detection means is installed in a fuel passage that is fed under pressure from a fuel tank, and the fuel that has passed through this detection means is In the device configured to supply the fuel to the fuel injection means, the control means forms a drive signal for the fuel injection means based on the different component concentration information detected by the different component detection means. The control means includes a storage means for storing the amount of fuel retained between the different component concentration detection means and the fuel injection means, and means for detecting a change in the different component concentration detected by the different component detection means. In preparation, the delay time until the fuel is injected from the different component detection means is calculated in accordance with the stored amount of accumulated fuel and the operating state of the internal combustion engine, and the delay time is calculated from when the concentration change is detected to when the fuel is injected. The drive signal is corrected after a lapse of time.

0012

[Operation] In the fuel supply device configured in this way,
When the concentration of different components in the fuel changes due to refueling or the like, and this concentration change is detected by the different component concentration detection means, the drive signal for the fuel injection means is changed to the stored value after the change in the detected concentration is detected. After the delay time has elapsed, correction is made in accordance with the new detected concentration. In this case, the delay time is determined by the amount of fuel accumulated between the foreign component detection means and the fuel injection means and the operating condition of the internal combustion engine, so that fuel with a changed concentration of foreign components reaches the fuel injection means. At that point, the drive signal is corrected so that an appropriate air-fuel ratio is always set.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Figure 1 shows its configuration, with fuel tank 1
1 stores fuel mixed with alcohol as a foreign component, for example. The fuel in the fuel tank 11 is transferred to the fuel pump 1
2 to the fuel passage 13, and this pressurized fuel is supplied in parallel to fuel injection valves 141 to 144 respectively set in each cylinder of a four-cylinder engine, for example. The fuel injection valves 141 to 144 are controlled to open by a drive signal from a control circuit 15 configured by an electronic control unit (ECU), and are opened in a time range corresponding to the pulse width of a pulsed drive signal, for example. Ru.

Here, the fuel pumped by the fuel pump 12 is supplied to the fuel filter 16, and the fuel that has passed through the fuel filter 16 is sent to the alcohol concentration sensor 17.
supplied to the department. And this alcohol concentration sensor 1
7 is supplied to fuel injection valves 141 to 144. The alcohol concentration sensor 17 detects the concentration of alcohol contained in the passing fuel, generates concentration information, measures the fuel temperature, and supplies the alcohol concentration information and temperature information to the control circuit 15.

The control circuit 15 executes well-known air-fuel ratio control based on various detection signals indicating the operating status of the engine, although details are not shown. The alcohol concentration information obtained is referenced to calculate and form a drive signal that sets the appropriate fuel injection amount, specifically, the valve opening time of the fuel injection valve.

In the fuel supply system configured as described above, the alcohol concentration sensor 17 is connected to the fuel injection valves 141 to 1.
44, the time it takes for the fuel that has passed through the alcohol concentration sensor 17 to reach the injection valves 141 to 144 can be sufficiently shortened. For example, from the alcohol concentration sensor 17 to the fuel injection valves 141 to 144
Assuming that the distance between the fuel pipe and the fuel pipe that constitutes the fuel passage between them is 350 mm and the inner diameter of the fuel pipe that constitutes the fuel passage between them is 8 mm, and the discharge amount of the fuel pump 12 is "116 (liters)/hour", the alcohol concentration sensor 17 is The time it takes for the fuel to reach the fuel injection valves 141 to 144 is approximately 0.5 seconds. Therefore, the time delay is substantially negligible.

However, approximately 1 cc of fuel is accumulated in the fuel injection valves 141 to 144, and when fuel injection is performed with the fuel injection pulse width during idling, for example, this accumulated approximately 1 cc of fuel is accumulated in the fuel injection valves 141 to 144. It takes about 10 seconds to inject this amount of fuel.

For example, when new fuel is supplied to the fuel tank 11 by refueling and the alcohol concentration of this new fuel is different from the alcohol concentration of the old fuel, when this new fuel reaches the alcohol concentration sensor 17, Based on the alcohol concentration information detected by the sensor 17, the control circuit 15 detects a change in alcohol concentration. Therefore, the control circuit 15 corrects the drive signal of the fuel injection valve based on this newly detected alcohol concentration information so that an appropriate air-fuel ratio is set, but in reality, the alcohol concentration sensor 1
New fuel is injected from the fuel injection valves 141 to 144 approximately 10 seconds after the change in alcohol concentration is detected in step 7, while old fuel is being injected during that time.

In order to deal with such problems, the memory device set in the control circuit 15 is configured to
The amount of fuel Qo accumulated in the ~144th section is memorized and set,
Fuel supply control corresponding to this accumulated fuel amount Qo is performed.

FIG. 2 shows the control flow of the control circuit 15. First, in step 101, the alcohol concentration sensor 17 detects the alcohol concentration in the fuel passing through the sensor 17. Step 1
At step 02, a fuel injection correction coefficient is searched based on the detected alcohol concentration information.

[0021] Here, the relationship between the alcohol concentration in the fuel and the fuel injection correction coefficient is determined in advance, and this relationship is stored in a storage device set in the control circuit 15 in the form of a map, for example. There is.

In step 103, alcohol concentration information from the alcohol concentration sensor 17 is monitored to determine whether or not the alcohol concentration has changed. For example, when the fuel tank 11 is refueled and the alcohol concentration of this newly refueled fuel is different from the alcohol concentration of the old fuel, when this new fuel reaches the alcohol concentration sensor 17 section, the alcohol concentration sensor 17 detects the new fuel. The alcohol concentration information obtained changes, and this is recognized by the control circuit 15.

When it is determined in step 103 that the alcohol concentration has changed, the process proceeds to step 104, and based on the alcohol concentration information detected at this time, the fuel injection amount "Δ" from each fuel injection valve 141 to 144 is adjusted each time.
Q" is calculated based on the following formula: ΔQ=Ti x q where Ti is the fuel injection time (drive signal pulse width) based on the correction coefficient obtained in step 102,
q is the fuel injection amount per unit time.

[0024] Once the fuel injection amount is calculated in this way,
Proceed to step 105. In this step 105, the fuel injection valves 141 to 144 stored in the control circuit 15
The fuel injection amount ΔQ obtained in step 104 is subtracted from the accumulated fuel amount Qo in the previous step to obtain the old fuel amount Q.

Next step 106 Then step 105
It is determined whether the old fuel amount Q obtained in step 1 is less than "0", that is, whether all the accumulated fuel (old fuel) has been replaced with new fuel. If it is determined that it has not been replaced yet, step Return to step 104 and step 104 ~
106 is repeated. And step 106
If it is determined that all of the fuel has been replaced with new fuel, the process proceeds to step 107, where fuel injection control is performed based on the correction coefficient obtained in response to this new fuel.

When such fuel supply control is performed, even if the alcohol concentration sensor 17 is installed in the middle of the fuel supply passage 13, the fuel whose alcohol concentration is detected by the sensor 17 is the fuel injection valve 141 ~ 1
When the alcohol concentration reaches 44 parts, fuel injection control is executed based on the alcohol concentration detected by the sensor 17 part.

Therefore, even if the alcohol concentration in the fuel changes due to refilling of new fuel to the fuel tank 11, the change in alcohol concentration is constantly monitored, and the change in alcohol concentration is monitored. is detected. Then, in accordance with this change in alcohol concentration, a correction coefficient is set at the time when this new fuel reaches the fuel injection valves 141 to 144, and responsive fuel injection control is executed to ensure an optimal air-fuel ratio. Become so.

If no change in alcohol concentration is detected in step 103, this means that new fuel with a changed alcohol concentration has not been supplied, so step 107 is performed.
Then, a correction coefficient corresponding to the alcohol concentration of the old fuel is set, and fuel injection control is executed.

FIG. 3 shows another embodiment of the processing in the control circuit 15. In this embodiment, when the throttle valve is closed (idle state), the fuel injection amount is small, so the fuel This takes advantage of the fact that it takes a long time for the old fuel in the injection valve to completely disappear.

That is, steps 101 to 103 perform the same processing as shown in FIG.
03, when it is detected that the alcohol concentration detected by the alcohol concentration sensor 17 has changed, step 2
01, the open/closed state of the throttle valve is detected. If it is determined in step 202 that the throttle valve is open, the process proceeds to step 203 to calculate a first delay time. If it is determined in step 202 that the throttle valve is closed and the engine is in an idle state, the process proceeds to step 204 to calculate a second delay time.

In steps 203 and 204, for the storage device set in the control circuit 15,
Delay times corresponding to the open and closed states of the throttle valve are stored and set in advance, and these stored values are used by searching. For example, a map as shown in FIG. 5 is stored in the storage device.

[0032] Then, in step 107, step 2
After the delay time obtained in step 03 or 204 has elapsed, fuel injection control is performed based on the correction coefficient corresponding to the new alcohol concentration obtained by the alcohol concentration sensor 17.

FIG. 4 shows yet another embodiment, in which the same processing as in the embodiment shown in FIG. 3 is performed from step 101 to step 202. And step 202
When it is determined that the throttle valve is open,
Proceeding to step 301, the alcohol concentration sensor 17 and the fuel injection valve 141 are checked in relation to the opening degree of the throttle valve.
The injection amount (injection pulse width) of the old fuel amount accumulated between 144 and 144 is calculated. In this case, a correction coefficient corresponding to the alcohol concentration of the old fuel is referred to.

[0034] In step 302, step 301
Based on the amount of injected fuel calculated in the fuel injection valve 141
The delay time is calculated by calculating the time until all of the old fuel within 144 is used up and replaced with new fuel. FIG. 6 shows the relationship between the opening degree of the throttle valve and the delay time, and this map is stored in the storage device of the control circuit 15.

Then, in step 107, fuel is injected based on the alcohol concentration in the fuel and the signal from the open/closed state of the throttle valve, taking into account the delay time calculated in step 302.

When it is determined in step 202 that the throttle valve is closed, in step 303 the injection amount of old fuel in the idling state is calculated in accordance with the alcohol concentration of the old fuel. And step 302
The delay time is calculated in relation to the opening degree of the throttle valve.

[0037]

According to the fuel supply system for an internal combustion engine configured as described above, after the alcohol concentration detection means detects the alcohol concentration, the fuel whose concentration has been detected is injected from the fuel injection valve. Fuel injection amount control is executed with the time lag corrected. Therefore, the optimum air-fuel ratio can always be obtained. In other words, when the concentration of different components such as alcohol in the fuel supplied to the fuel injection valve changes due to refueling etc., and this change is detected, the fuel that accumulates in the fuel injection means portion changes after the concentration of the different components changes. After all the fuel is injected, fuel injection control corresponding to the newly detected concentration of different components of the fuel is executed. Therefore, occurrence of engine stall etc. is reliably prevented.

[Brief explanation of drawings]

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

FIG. 2 is a flowchart illustrating the flow of processing executed in the control circuit of the embodiment.

FIG. 3 is a flowchart illustrating another embodiment of the control circuit.

FIG. 4 is a flowchart illustrating still another embodiment of the control circuit.

FIG. 5 is a diagram showing the relationship between the opening/closing state of the throttle valve and the delay time.

FIG. 6 is a diagram showing the relationship between throttle valve opening and delay time.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11... Fuel tank, 12... Fuel pump, 13... Fuel passage, 141-144... Fuel injection valve, 15... Control circuit, 1
6...Fuel filter, 17...Alcohol (different component) concentration sensor.

Claims (1)

[Claims] 1. Different component concentration detection means, which is set in a fuel passage through which fuel containing different components is pumped and supplied, and detects the concentration of the different components in the fuel; the fuel that has passed through the different component concentration detection means; The control means includes a fuel injection means supplied through the fuel passage, and a control means for forming a drive signal for the fuel injection means in accordance with an appropriate air-fuel ratio of the internal combustion engine, and the control means includes the different component detection means. a storage means for storing an amount of fuel accumulated between the fuel injection means; a means for detecting a concentration change based on the concentration of a different component detected by the different component concentration detection means; Based on the fuel injection amount from the corresponding fuel injection means and the accumulated fuel amount stored in the storage means, the fuel that has passed through the different component concentration detection means after the different component concentration has changed is detected by the fuel injection means and a delay time calculation means for calculating the delay time necessary for reaching the point, and a correction coefficient corresponding to the different component concentration information detected by the different component concentration detection means after the different component concentration has changed. Based on
A fuel supply device for an internal combustion engine, wherein the drive signal is corrected after the delay time has elapsed after detecting the concentration change.