JPH0674120A - Controller for vehicle fuel pump - Google Patents

Abstract

PURPOSE:To prevent the disorder of air-fuel ratio by dissolving the shortage of burning pressure at the time of fuel return after electric power consumption is saved by stopping a fuel pump and at the same time the increase of manufacturing cost due to the complexity of structure is prevented. CONSTITUTION:An ECU to stop a fuel pump when it is decided that an engine revolution number Ne has become less than a fuel cut revolution number alphafollowing the deceleration of a vehicle and to start the fuel pump when it is decided that the engine revolution number Ne has become less than a pump start revolution number gamma set on a higher revolution side than a fuel return revolution number beta, is equipped, so the fuel pump is stopped during fuel cut, and electric power consumption is saved. As the fuel pump is started ahead of fuel return, the shortage of burning pressure at the time of fuel return is dissolved, and there is no fear of structure becoming complex, as the start of the fuel pump is only made to precede fuel return as above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular fuel pump control device, and more particularly, to stopping a fuel pump for supplying fuel to an internal combustion engine while the internal combustion engine is being cut off. The present invention relates to a control device for a vehicle fuel pump that reduces power consumption.

[0002]

2. Description of the Related Art As is well known, in recent years, internal combustion engines carry out a so-called fuel cut in which fuel injection is stopped when the vehicle is decelerating for the purpose of improving fuel efficiency and reducing emissions. This fuel cut is performed when the throttle valve is closed when the engine speed is equal to or higher than the preset fuel cut speed (for example, 1600 rpm), and the engine speed is lowered and set in advance. Also, when the fuel return rotational speed becomes lower than 1200 rpm, for example, or when the throttle valve is opened, so-called fuel return is performed. However, in the conventional internal combustion engine, the fuel pump that supplies the fuel to the fuel injection valve continues to operate even during the fuel cut, so that there is a problem that useless electric power is consumed.

Therefore, in order to reduce wasteful power consumption, for example, a vehicle fuel pump control device disclosed in Japanese Utility Model Publication No. 60-27822 is proposed.

This fuel pump control device stops the fuel pump in synchronism with the fuel cut and restarts the fuel pump in synchronism with the fuel recovery, thus saving the power consumption of the fuel pump during the fuel cut. is doing. Also, when the fuel pump is stopped in this way, the fuel pressure in the fuel path drops, and even if the fuel pump is restarted, the fuel pressure does not immediately reach the specified pressure, and the air-fuel ratio temporarily becomes lean. It gets disturbed. Therefore, in this fuel pump control device, an accumulator is provided in the fuel path to prevent the fuel pressure from decreasing due to the stop of the fuel pump.

[0005]

The control device for a vehicle fuel pump described in the prior art publication prevents an insufficient fuel pressure at the time of fuel recovery by providing an accumulator in the fuel path as described above. Therefore, the installation of the accumulator complicates the entire structure, resulting in a high manufacturing cost.

Therefore, according to the present invention, the power consumption can be reduced by stopping the fuel pump during the fuel cut, and the manufacturing cost can be prevented from soaring due to the complicated structure, and the fuel pressure shortage at the time of fuel recovery can be eliminated. Another object of the present invention is to provide a control device for a vehicle fuel pump capable of preventing the disturbance of the air-fuel ratio.

[0007]

As shown in FIG. 1, an internal combustion engine M is a control system for a vehicle fuel pump according to the present invention.
The pump driving means M3 for arbitrarily starting and stopping the fuel pump M2 for supplying fuel to the fuel cell 1, the pump stop timing according to the fuel cut of the internal combustion engine M1, and the pump start timing preceding the fuel return of the internal combustion engine M1. When the pump stop timing is determined by the stop / start timing determining means M4 and the start / stop timing determining means M4,
A pump stop command is output to the pump drive means M3, and a pump start command is output to the pump drive means M3 when the pump start timing is determined by the start / stop timing determination means M4. And is equipped with.

[0008]

In the present invention, when the fuel cut of the internal combustion engine M1 is performed, the pump stop timing corresponding to the fuel cut and the pump start timing preceding the fuel return stop.
The start timing determination means M4 makes a determination, and the stop / start instruction means M5 outputs a pump stop instruction at the pump stop timing and a pump start instruction at the pump start timing to the pump drive means M3. The fuel pump M2 is accordingly stopped and started by the pump drive means M3.

Therefore, during fuel cut, the fuel pump M2 is stopped to save power consumption and
Since the fuel pump M2 is started prior to the fuel return, the fuel pressure is already raised to the specified value at the time of the fuel return, and the disturbance of the air-fuel ratio due to the insufficient fuel pressure is prevented. Since the fuel pressure insufficiency at the time of fuel recovery is eliminated by advancing the pump start timing in this way, there is no possibility that the structure will be complicated.

[0010]

EXAMPLES Examples of the present invention will be described below.

FIG. 2 is a schematic configuration diagram showing an internal combustion engine and peripheral equipment to which a vehicle fuel pump control apparatus according to an embodiment of the present invention is applied.

As shown in the figure, a fuel injection valve 3 is installed in each cylinder in an intake pipe 2 of an internal combustion engine 1, and the fuel stored in a fuel tank 4 is used as a fuel in these fuel injection valves 3. It is supplied by a pump 5 via a filter 6. The surplus of the supplied fuel is returned to the fuel tank 4 via the pressure regulator 7, and the fuel supplied to each fuel injection valve 3 is regulated to 2.5 kg / cm ² by the pressure regulator 7, and the fuel injection valve is adjusted. It is injected into the intake pipe 2 as the valve 3 is opened and closed. A throttle valve 8 is provided upstream of the fuel injection valve 3 in the intake pipe 2, and the intake air passing through the intake pipe 2 through an air filter (not shown) is injected with fuel after the flow rate is adjusted by the throttle valve 8. It is mixed with the fuel injected from the valve 3 and introduced as a mixture into the combustion chamber 9 of each cylinder through an intake valve (not shown). A spark plug 10 is installed in the internal combustion engine 1 so as to face the combustion chamber 9 and
The air-fuel mixture introduced into the interior is ignited by the ignition plug 10 and burned, and then passes through an exhaust valve (not shown) and the exhaust pipe 1
1 is discharged to the outside.

Each of the spark plugs 10 is connected to a distributor 12, and the distributor 12 distributes the high voltage generated in the ignition coil 13 to the spark plugs 10 of the cylinders in association with the rotation of the crankshaft 14 of the internal combustion engine 1. Supply. The fuel pump 5 is connected to a vehicle battery 17 via a normally open contact 15a of a relay 15 and an ignition switch 16, and a coil 15b of the relay 15 is connected to an electronic control unit 21 (hereinafter simply referred to as "ECU"). The relay 15 is controlled to open / close by the ECU 21.

The ECU 21 includes an idle switch 22 for detecting a fully closed state of the fuel injection valve 3, the ignition coil 13, and the throttle valve 8 described above, and a rotation speed sensor 23 provided in the distributor 12 for detecting an engine rotation speed Ne.
And a water temperature sensor 24 for detecting the cooling water temperature Tw, respectively. The ECU 21 includes a CPU 21a and a ROM
21b and RAM 21c constitute a logical operation circuit,
It is connected to the input / output unit 21e via the common bus 21d to perform input / output with the outside.

As is well known, the ECU 21 controls the fuel injection valve based on various detected values such as the engine speed Ne detected by the speed sensor 23 and the intake air amount detected by an air flow meter (not shown). 3 to output a drive pulse to perform fuel injection, and when the vehicle is decelerating and a predetermined fuel cut condition is satisfied, the pulse output to the fuel injection valve 3 is interrupted to stop fuel injection. Make a cut. In addition, in the present embodiment, the ECU 21 stops the fuel pump 5 in synchronization with the start of the fuel cut, and starts the fuel pump 5 prior to the fuel recovery.

Next, an outline of the operation control of the fuel pump executed by the vehicle fuel pump control device configured as described above will be described.

FIG. 3 is a time chart showing the relationship between the fuel injection of the vehicle fuel pump control apparatus according to one embodiment of the present invention and the execution status of the fuel pump, and FIG. 4 is a vehicle according to one embodiment of the present invention. 5 is a time chart showing a delay in rising of fuel pressure with respect to application of voltage to the fuel pump of the control unit for the fuel pump for vehicle, FIG. 5 is a fuel recovery stored in the ROM of the control unit for the vehicle fuel pump according to one embodiment of the present invention FIG. 6 is an explanatory view showing a map for calculating the rotational speed, and FIG. 6 shows a map for calculating a basic pump starting rotational speed stored in the ROM of the vehicle fuel pump control device according to the embodiment of the present invention. FIG. 7 is an explanatory view showing a map for calculating a voltage correction coefficient stored in the ROM of the vehicle fuel pump control device according to one embodiment of the present invention, and FIG. 8 is one embodiment of the present invention. Vehicle fuel It is an explanatory diagram showing a map for calculating a rotation reduction ratio correction coefficient stored in the ROM of the control device of the pump.

The time chart shown in FIG. 3 is based on the premise that the throttle valve 8 is closed.
When the rotational speed Ne of the fuel injection valve 3 is equal to or higher than the preset fuel cut rotational speed α (for example, 1600 rpm), the throttle valve 8 is closed by the suspension of the accelerator operation and the vehicle starts decelerating, the fuel of the fuel injection valve 3 A fuel cut to stop injection is performed. In the figure, fuel cut is performed when the engine speed Ne is the fuel cut speed α.
Then, when the engine speed Ne gradually decreases and becomes lower than the preset fuel return speed β (for example, 1200 rpm) or when the throttle valve 8 is opened, the fuel injection of the fuel injection valve 3 is performed. Fuel restart is resumed. The above control is similar to the fuel injection control of a general internal combustion engine.

In addition, in this embodiment, in order to save the power consumption of the fuel pump 5 during the fuel cut, the fuel pump 5 is stopped during the fuel cut. Here, FIG.
As shown in, when the fuel pump 5 is stopped, the fuel pressure in the fuel path near the fuel injection valve 3 is reduced from, for example, 2.5 kg / cm ² to 2 kg / cm ² (due to the action of the pressure regulator 7). (It does not decrease to 0 kg / cm ² ), the fuel pump 5 starts in response to the voltage application, and a predetermined response time TD (for example, 100 msec) is required to actually raise the fuel pressure to a specified value, and the fuel is restored. If the fuel pressure at that time has not reached the specified value, the actual fuel injection amount may decrease and the air-fuel ratio may be disturbed to the lean side.

Therefore, in the present embodiment, the stop timing of the fuel pump 5 is synchronized with the fuel cut as in the fuel pump control device described in the prior art, but the start timing of the fuel pump 5 is , The fuel return is preceded by the response time TD. Therefore, when the fuel is restored, the fuel pressure has already risen to the specified value, and it is possible to prevent the air-fuel ratio from being disturbed due to insufficient fuel pressure. The start timing of the fuel pump 5 is determined by using the engine speed Ne as a guide as in the fuel cut and the fuel return, and the engine is started up to the pump start speed γ set higher than the fuel return speed β. The fuel pump 5 is started when the rotation speed Ne decreases. That is, the pump starting rotational speed γ is set so that the response time TD is required for the engine rotational speed Ne to decrease from the pump starting rotational speed γ to the fuel return rotational speed β.

Since the fuel pump 5 is started earlier than the fuel return in this way, the fuel pressure shortage at the time of the fuel return is eliminated, so that the fuel pump control device described in the prior art is used. It is not necessary to provide an accumulator or the like, and there is no possibility that the structure will be complicated.

By the way, the above-mentioned pump start-up speed γ
Is the fuel return rotational speed β, the applied voltage V (=
It is desirable to change it according to the battery voltage) and the rate of decrease ΔNe of the engine speed Ne. Since the higher the fuel return speed β, the earlier the fuel recovery, the pump start-up speed γ is set to the high speed side. Further, the lower the applied voltage V is, the worse the response of the fuel pump 5 is. Therefore, the pump starting rotation speed γ is set to the high rotation side, and further, the reduction rate ΔNe of the engine rotation speed Ne due to the difference in gear position or the like. Is larger (the speed of rotation is steeper), the fuel return speed β decreases faster, so the pump start-up speed γ is set to the high speed side.

The procedure for calculating the pump starting rotational speed γ will be described below. As shown in FIG. 5, the above-described fuel return rotational speed β is higher when the cooling water temperature Tw is still low because warm-up has not been completed. Is set to the side, and the fuel is returned early. As shown in FIG. 6, the basic pump start-up speed γBASE, which is the reference for calculating the pump start-up speed γ, is set as a value on the higher rotation side by adding a predetermined correction value Ta to this fuel return speed β. Is set. On the other hand, as shown in FIG. 7, the voltage correction coefficient f (FPB) is set to a larger value as the applied voltage V of the fuel pump 5 is lower, and is 1 when the applied voltage V is maximum.
, And as shown in FIG. 8, the rotation reduction rate correction coefficient f (
ΔNe) is the decrease rate Δ of the engine speed Ne per unit time
The larger Ne is, the larger the value becomes, and the rotation reduction rate ΔNe
Set to 1 when is minimum. Then, the pump starting rotation speed γ is calculated from each value thus obtained according to the following equation.

Γ = γBASE × f (FPB) × f (ΔNe) Therefore, the higher the fuel return rotational speed β, the lower the applied voltage V of the fuel pump 5, and the greater the decrease rate ΔNe of the engine rotational speed Ne, the more the pump starts. Since the rotation speed γ is set to the high rotation side, the fuel pressure surely reaches the specified value at the time of fuel recovery, regardless of the difference in the fuel recovery rotation speed β, the applied voltage V or the rotation reduction rate ΔNe. Therefore, in any case, it is possible to reliably prevent the disturbance of the air-fuel ratio due to insufficient fuel pressure.

As described above, even before the engine speed Ne drops to the fuel return speed β, the fuel is restored when the throttle valve 8 is opened, so that the fuel pump 5 is started. The need arises. However, since it is not possible to predict when the throttle will be opened, it is impossible to start the fuel pump 5 prior to the fuel return. Therefore, in such a case, the fuel pump 5 is started immediately after the opening of the throttle valve 8 to deal with the problem.

Next, the fuel cut / pump control process executed by the ECU 21 of the vehicle fuel pump control device configured as described above will be described.

FIG. 9 is a flowchart showing a fuel cut / pump control routine executed by the ECU of the vehicle fuel pump control apparatus according to the embodiment of the present invention.

The routine shown in FIG. 9 is performed at a predetermined timing, for example, at a crank angle of 36 when the internal combustion engine 1 starts operating by turning on the ignition switch 16.
It is executed every 0 degrees. Also, during this operation, EC
U21 excites the coil 15b of the relay 15 to close the normally open contact 15a, and operates the fuel pump 5 by the voltage application from the battery 17 to supply the fuel to the fuel injection valve 3.

First, the ECU 21 determines in step S1 whether or not the preset fuel cut condition is satisfied. In this embodiment, it is determined whether or not the throttle valve 8 is closed when the engine speed Ne is equal to or higher than the fuel cut speed α, and when the fuel cut condition is not satisfied, the fuel cut / pump control routine is executed. finish. When the fuel cut condition is satisfied in step S1, the output of the drive pulse to the fuel injection valve 3 is interrupted to perform the fuel cut in step S2, and the coil 15b of the relay 15 is demagnetized in step S3 to be normally deenergized. The open contact 15a is opened and the fuel pump 5 is stopped.
Next, in step S4, the driver opens the throttle valve 8
Is not operated, it is determined in step S5 whether or not the flag is set. Since the flag is cleared at this point, the process proceeds to step S6 and the cooling water temperature Tw detected by the water temperature sensor 24 is detected. , Battery voltage V, engine speed N detected by the speed sensor 23
Enter e. Then, in step S7, as described above, the basic pump start-up speed γBASE is multiplied by the voltage correction coefficient f (FPB) and the rotation reduction rate correction coefficient f (ΔNe) to calculate the pump start-up speed γ. It is determined whether or not the number Ne has decreased to less than the pump start-up speed γ, and if it has not decreased yet, the processes of steps S4 to S8 are repeated.

When the engine speed Ne drops below the pump starting speed γ in step S8, the coil 15b of the relay 15 is excited to close the normally open contact 15a and start the fuel pump 5 in step S9. , Step S
The flag is set at 10 and the process proceeds to step S11.
Therefore, as shown in FIG. 4, the fuel pressure gradually rises due to the activation of the fuel pump 5. Furthermore, step S
In 11, it is determined whether the engine speed Ne has decreased to less than the fuel return speed β, and if it has not decreased yet, the process returns to step S4, and the flag is set in step S5, and the process proceeds to step S11. This step S
4, the process of step S5 and step S11 is repeated.
When the engine speed Ne drops below the fuel return speed β in step S11, the output of the drive pulse to the fuel injection valve 3 is restarted to return the fuel in step S12, and the flag is cleared in step S13. Then, the fuel cut / pump control routine is ended. That is, since the fuel pump 5 is started prior to the fuel return, the fuel pressure has already risen to the specified value at the time of the fuel return, and the disturbance of the air-fuel ratio is prevented in advance.

On the other hand, as described above, after the fuel is cut in step S2 and the fuel pump 5 is stopped in step S3, in step S8 or step S11 the engine speed Ne is set to the pump starting speed γ or the fuel return speed. Before decreasing to less than several β, the throttle valve 8 is opened in step S4.
Is opened, the fuel pump 5 is started in step S14, and the fuel is restored in step S12. That is, when the fuel is restored by opening the throttle valve 8, the fuel pump 5 is immediately activated.

As described above, in this embodiment, the internal combustion engine M1
The internal combustion engine 1, the fuel pump 5 as the fuel pump M2, and the relay 15 as the pump driving means M3,
Further, as the stop / start timing determination means M4, step S
1. EC when executing the processing of step S6 to step S8, the ECU 21 when executing the processing of step S3 and step S9 as the stop / start instruction means M5
U21 works respectively.

As described above, the vehicle fuel pump control system according to the present embodiment includes the relay 15 for arbitrarily starting and stopping the fuel pump 5 for supplying fuel to the internal combustion engine 1, and the engine rotation as the vehicle decelerates. When it is determined that the number Ne becomes less than the fuel cut speed α, the normally open contact 1 of the relay 15
5a is opened to stop the fuel pump 5, and the engine speed Ne
Is determined to be less than the pump start-up speed γ set on the higher rotation side than the fuel return rotation speed β, the relay 15
The normally open contact 15b of the fuel cell is closed to start the fuel pump 5 E
CU21 and. This structure corresponds to the embodiment of the present invention.

Therefore, during fuel cut, the fuel pump 5
Power consumption can be reduced by stopping the fuel pump 5
Since the fuel pressure shortage at the time of fuel recovery is resolved by making the start time of the fuel advance before the fuel recovery, there is no possibility that the structure will be complicated, and after preventing a sharp rise in the manufacturing cost,
It is possible to prevent the air-fuel ratio from being disturbed due to insufficient fuel pressure.

Further, in the vehicle fuel pump control system of this embodiment, the ECU 21 causes the ECU 21 to determine the pump start-up speed γ for determining the start-up time of the fuel pump 5, the fuel return speed β to be high, and the fuel The lower the applied voltage V of the pump 5 and the larger the rotation reduction rate ΔNe of the internal combustion engine 1, the higher the rotation speed is set.

Therefore, the fuel pressure can surely reach the specified value at the time of fuel recovery regardless of the fuel recovery rotational speed β, the applied voltage V or the rotation reduction rate ΔNe, and the above-mentioned turbulence of the air-fuel ratio due to insufficient fuel pressure is further suppressed. It can be prevented more reliably.

By the way, in the above embodiment, the fuel pump 5 is stopped in synchronization with the fuel cut of the internal combustion engine 1, but the pump stop timing does not necessarily have to be synchronized with the fuel cut. Therefore, for example, when the fuel cut time is extremely short, such as during a gear shift, the fuel pump 5 is stopped for a short time and power consumption can hardly be saved.
The fuel pump 5 may be continuously operated without being stopped.

Further, in the above embodiment, when calculating the pump starting rotation speed γ, the fuel return rotation speed β, the applied voltage V of the fuel pump 5, and the reduction rate ΔNe of the engine rotation speed Ne are taken into consideration. It is not always necessary to consider the factor of. Therefore, for example, the basic pump starting rotational speed γBASE based on the fuel return rotational speed β is multiplied by only the voltage correction coefficient f (FPB) corresponding to the applied voltage V to calculate the pump starting rotational speed γ, or the basic pump starting rotational speed γ. The pump starting rotation speed γ may be calculated by multiplying the rotation speed γBASE by only the rotation decrease rate correction coefficient f (ΔNe) corresponding to the rotation decrease rate ΔNe.

[0039]

As described above, according to the vehicle fuel pump control device of the present invention, the fuel pump can be stopped during the fuel cut to save the power consumption, and the fuel pump can be started at the fuel recovery timing. By advancing further, the fuel pressure shortage at the time of fuel return is eliminated, so there is no possibility of complicating the structure, preventing the rise in manufacturing cost, and disturbing the air-fuel ratio due to insufficient fuel pressure. Can be prevented.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram conceptually showing the content of one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an internal combustion engine and peripheral equipment to which a vehicle fuel pump control device according to an embodiment of the present invention is applied.

FIG. 3 is a time chart showing the relationship between the fuel injection and the execution status of the fuel pump of the vehicle fuel pump control device according to the embodiment of the present invention.

FIG. 4 is a time chart showing a fuel pressure rise delay with respect to voltage application to the fuel pump of the vehicle fuel pump control device according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a map for calculating a fuel return rotational speed stored in a ROM of a vehicle fuel pump control device according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a map for calculating a basic pump starting rotational speed stored in a ROM of a vehicle fuel pump control device according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a map for calculating a voltage correction coefficient stored in the ROM of the control device for the vehicle fuel pump according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a map for calculating a rotation reduction rate correction coefficient stored in a ROM of a vehicle fuel pump control device according to an embodiment of the present invention.

FIG. 9 is a flowchart showing a fuel cut / pump control routine executed by the ECU of the vehicle fuel pump control apparatus according to the embodiment of the present invention.

[Explanation of reference numerals] M1 internal combustion engine M2 fuel pump M3 pump drive means M4 stop / start timing determination means M5 stop / start command means 1 internal combustion engine 5 fuel pump 15 relay 21 ECU

Claims (1)

[Claims] 1. A pump drive means for arbitrarily starting and stopping a fuel pump for supplying fuel to an internal combustion engine, a pump stop timing according to a fuel cut of the internal combustion engine, and a pump start prior to fuel recovery of the internal combustion engine. A stop / start timing determination means for determining the respective timings, and a pump stop command is output to the pump driving means when the start / stop timing determination means determines the pump stop timing, and the start / stop timing determination is performed. A control device for a fuel pump for a vehicle, comprising: stop / start command means for outputting a pump start command to the pump drive means when the pump start timing is determined by the means.