JPH10299599A - Fuel supply device for internal combustion engine - Google Patents

Abstract

(57) Abstract: In a fuel supply device that adjusts a fuel pressure supplied to an internal combustion engine by controlling a driving force of a fuel pump, the responsiveness of the fuel pump even when a characteristic change occurs in a fuel supply system. To ensure. A fuel supply device includes a pump for sucking and discharging fuel, a fuel line for flowing fuel from the pump to an engine, and a fuel filter for capturing foreign matter contained in the supplied fuel. And EC
The U (electronic control unit) 50 controls the pump 12 so that the fuel pressure supplied to the engine 22 becomes a target fuel pressure according to the operating state of the engine 22. When a characteristic deviation occurs between the pump voltage applied to the pump 12 and the amount of fuel discharged from the pump 12, the ECU 50 calculates a learning value, and further increases or decreases the pump voltage based on the learning value. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for supplying fuel to an internal combustion engine. More specifically, the present invention relates to a fuel supply device for an internal combustion engine in which fuel in a fuel tank is sucked and discharged by a pump to be pumped to the internal combustion engine, and the fuel pressure is adjusted according to the operating state of the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, there is a fuel supply apparatus in which a fuel pressure supplied to an internal combustion engine is adjusted in accordance with an operation state of the internal combustion engine. In this device, the amount of fuel discharged from the fuel pump is adjusted by controlling the driving force of the fuel pump, and the pressure of the fuel supplied to the internal combustion engine is controlled. The computer calculates a target value of the amount of fuel to be discharged by the pump in accordance with the operation state of the internal combustion engine, and controls the driving force of the pump based on the target value.

In such a device, when the internal combustion engine is accelerated or decelerated, the amount of fuel consumed by the internal combustion engine rapidly increases or decreases, so that the difference between the actual fuel pressure and the required fuel pressure increases. . Therefore, the time until the fuel pressure reaches the target value becomes longer, and a response delay occurs. Due to this response delay, the amount of fuel supplied to the internal combustion engine becomes excessive or deficient.

Therefore, conventionally, for example, Japanese Patent Application Laid-Open No. Sho 62-10
The device described in Japanese Patent No. 1875 is intended to solve such a problem. In such a device,
When a difference occurs between the actual fuel pressure and the target fuel pressure, a correction value for correcting the pressure difference is calculated.
Then, the driving force of the pump is increased or decreased by the correction value. For example, when the actual fuel pressure is lower than the target fuel pressure, the driving force of the pump is increased, and when the actual fuel pressure is higher than the target fuel pressure, the driving force of the pump is reduced. As a result, the amount of fuel discharged from the pump is increased or decreased as compared with the time of normal control, and a desired fuel pressure can be quickly obtained in the internal combustion engine.

[0005]

Generally, a fuel pump is provided with a filter for trapping foreign substances contained in fuel. If the filter is clogged, the pressure loss caused by the fuel pressure supplied from the pump increases. Further, pressure loss also occurs in a fuel pipe leading from the pump to the internal combustion engine. These pressure losses can change over time.

Here, in the case of the apparatus described in the above-mentioned publication, if a pressure loss occurs in the fuel supply system or the pressure loss changes over time, the correction value related to the driving force of the pump is reduced accordingly. Becomes larger. Therefore, the greater the correction value, the worse the convergence to the target fuel pressure and the lower the responsiveness.

[0007] In addition, there may be a slight individual difference between the individual pumps manufactured. In this case, even if the same driving force is supplied, the amount of fuel discharged from each pump differs.
Similarly, the pressure loss generated in the pipe through which the fuel flows may be different. As described above, when there is a difference between the performances of the individual devices, the difference is compensated by the correction value each time the pump driving force is calculated, and the convergence to the target fuel pressure deteriorates as described above. Resulting in.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to control a fuel pressure supplied to an internal combustion engine by controlling a driving force of a fuel pump. It is an object of the present invention to provide a fuel supply device for an internal combustion engine which can ensure the responsiveness of a fuel pump even when a characteristic change occurs in a fuel supply system.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a fuel in a fuel tank is sucked and discharged by a pump and a driving force of the pump is controlled. Operating state detecting means for detecting an operating state of the internal combustion engine, and an operation for detecting a fuel pressure supplied to the internal combustion engine. Feedback value calculating means for calculating a feedback value of the driving force of the pump so as to be a target fuel pressure according to the state; and learning means for calculating a learning value for compensating for a deviation in characteristics relating to the fuel discharge amount of the pump, A fuel supply device for an internal combustion engine, comprising: pump control means for controlling a driving force of a pump based on a calculated feedback value and a learned value learned.

In the above arrangement, the fuel in the fuel tank is supplied to the internal combustion engine by operating the pump, and the pressure is adjusted to a target fuel pressure according to the operating state of the internal combustion engine. You. The target fuel pressure is calculated according to the operating state of the internal combustion engine, and if the operating state changes rapidly, the target fuel pressure changes accordingly. The pump control means performs so-called feedback control for adjusting the driving force of the pump so that the actual fuel pressure converges to the target fuel pressure. More specifically, if the difference between the actual fuel pressure and the target fuel pressure is large, the pump control means sharply changes the pump driving force, and the smaller the difference, the smaller the change in the pump driving force.

However, in general, the fuel supply system including the pump may change over time, in which case the characteristics of the pump driving force and the amount of fuel discharged from the pump deviate from the initial characteristics. In this state, even if a predetermined driving force is supplied to the pump, a desired fuel discharge amount cannot be obtained from the pump, and it becomes difficult for the actual fuel pressure to converge to the target fuel pressure. Here, the learning means calculates a learning value to compensate for the deviation of the characteristic relating to the fuel discharge amount, and the pump driving force is always corrected by the learning value. As a result, the characteristics are corrected so as to be relatively initial characteristics.
As described above, since the deviation of the characteristic is always compensated by the learning value, the change width of the pump driving force due to the feedback is suppressed relatively small, and the convergence of the fuel pressure is secured.

Therefore, even if the characteristics related to the fuel discharge amount change over time, the controllability of the fuel pressure is ensured, and the desired fuel pressure can be obtained relatively quickly in the internal combustion engine.
According to a second aspect of the present invention, the learning means increases or decreases the learning value based on the transition tendency of the calculated feedback value so that the feedback value is reduced.

In the above configuration, the value of the learned value is increased or decreased based on the feedback value, that is, the difference between the actual fuel pressure and the target fuel pressure so as to reduce the value. For example, if the actual fuel pressure is lower than the target fuel pressure, the value of the learned value is increased, and if the actual fuel pressure is higher than the target fuel pressure, the value of the learned value is decreased. Therefore, even if the characteristic related to the fuel discharge amount of the pump changes over time, the characteristic is appropriately corrected by the learning value, and the convergence of the fuel pressure is ensured.

[0014] The invention according to claim 3 is characterized in that the fuel flow rate range of the pump is divided into a plurality of ranges, and the learning value is increased or decreased for each flow rate range. In the above configuration, a plurality of learning values are set for each fuel flow rate of the pump, and the driving force of the pump is corrected using the learning value corresponding to the fuel discharge amount of the pump.
Therefore, even if the characteristic related to the fuel discharge amount of the pump changes over time for each flow rate region, the characteristic is appropriately corrected by the learning value set for each flow rate region. As a result, the controllability of the fuel discharge amount of the pump is secured in the entire flow rate range, and the fuel pressure is secured.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying a fuel supply device for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a fuel supply device of this embodiment. As shown in FIG. 1, the apparatus includes a fuel tank 11 in which fuel is stored and a tank 1 for storing the fuel.
1 includes an electric fuel pump 12 housed in the fuel cell 1, and a fuel line 17 connected to a discharge port 12 b of the pump 12.

The pump 12 is mounted on the tank 11 via a bracket (not shown). The pump 12 has a built-in DC motor (not shown) and an impeller (impeller: not shown) driven by the motor. When the motor is driven by the energization and the impeller is rotated, the pump 12 operates and the fuel in the tank 11 is sucked up by the pump 12 through the strainer 16 and discharged from the discharge port 12b. The amount of fuel discharged from the pump 12 is determined based on the voltage value supplied to the motor, that is, the rotation speed of the impeller driven by the motor. The fuel pressure PF in the fuel line 17 is determined by the amount of fuel discharged from the pump 12.

A fuel line 17 extending from a discharge port 12b of the pump 12 extends out of the tank 11 through an upper cover 18 of the tank 11. A fuel filter 19 is provided in the middle of the fuel line 17, and the end of the fuel filter 19 is connected to a delivery pipe 20. A plurality of injectors 21 provided on the delivery pipe 20 are arranged corresponding to each cylinder of the internal combustion engine (gasoline engine) 22. Each injector 21 is a nozzle with an electromagnetic valve, and opens when energized and closes when energized. An intake passage 23 connected to the engine 22 guides air to each cylinder of the engine 22. Throttle valve 24 provided in intake passage 23
Opens and closes the passage 23 by operating in conjunction with the operation of an accelerator pedal (not shown). By adjusting the opening degree (throttle opening degree) TA of the valve 24, the amount of air (intake amount) QA taken into each cylinder of the engine 22 through the intake passage 23 is adjusted.

After the foreign matter is removed from the fuel discharged from the pump 12 by the filter 19, the fuel is pumped through the fuel line 17 to the delivery pipe 20, and further, is delivered to the delivery pipe 20.
Is distributed to each injector 21. At this time,
The fuel pressure PF in the delivery pipe 20 is adjusted according to the amount of fuel discharged from the pump 12. The distributed fuel is supplied to each of the corresponding cylinders by being injected from each of the injectors 21. By burning a mixture of fuel and air supplied to each cylinder,
The crankshaft (not shown) of the engine 22 is rotated, and power is obtained in the engine 22.

A drive circuit 40 for driving the pump 12
Supplies the voltage charged in the battery 41 to the motor of the pump 12. The drive circuit 40 adjusts a voltage value supplied to the pump 12.

A throttle sensor 45 provided in the vicinity of the throttle valve 24 detects the opening degree TA of the valve 24 and outputs a signal corresponding to the magnitude. The sensor 45 includes a well-known idle switch (not shown). This switch is turned on when the valve 24 is fully closed, and an idle signal ID indicating that the valve is fully closed.
L is output. The fuel pressure sensor 46 provided in the delivery pipe 20 detects the pressure of the fuel pressure-fed to each injector 21, that is, the fuel pressure PF in the delivery pipe 20, and outputs a signal corresponding to the magnitude. Engine 22
Is provided with a rotational speed sensor 47 provided at the engine speed NE, that is, a rotational speed of a crankshaft (not shown).
Is detected, and a signal corresponding to the magnitude of the value is output. The sensor 47 intermittently detects the rotation of the crankshaft at predetermined angles in synchronization with the rotation phase of the crankshaft, and outputs the detection result as a pulse signal. Water temperature sensor 4 provided in engine 22
8 detects the temperature (cooling water temperature) THW of the cooling water flowing inside the engine 22, and outputs a signal according to the magnitude. Intake pressure sensor 49 provided in intake passage 23
Detects the intake pressure PM in the passage 23 and outputs a signal corresponding to the detected pressure. These sensors 45-4
9, the operating state of the engine 22 is detected.

The ECU 50 includes an input signal processing circuit, a memory,
It has a backup RAM, an arithmetic circuit, an output signal processing circuit, and the like. Memory and backup RA in ECU 50
M stores various parameters used in the processing described below. The above-described various sensors 45 to 49, the injector 21, the drive circuit 40, and the battery 41 are connected to the ECU 50, respectively. The ECU 50 inputs signals output from the various sensors 45 to 49 described above. ECU50
Controls the injectors 21 and the drive circuit 40 based on these input signals in order to execute the fuel injection control and the fuel supply control described later.

The fuel injection control is to control the amount of fuel injected from each injector 21 to each cylinder by controlling the valve opening time of each injector 21 according to the operating state of the engine 22. The fuel supply control is to control the drive circuit 40 in accordance with the operation state of the engine 22 and to control the pump 12, thereby controlling the amount of fuel discharged from the pump 12. Thereby, the fuel pressure PF supplied to each injector 21 is adjusted.

FIG. 2 is a flowchart showing a "fuel injection control routine" relating to the processing contents of the fuel injection control. The ECU 50 periodically executes this routine at predetermined time intervals when the engine 22 is operating.

In step 100, the ECU 50 detects various sensors 45, 47 to 49,
Various parameters TA, IDL,
The values related to NE, THW, and PM are read as input values.

In step 110, the ECU 50 determines whether or not the engine 22 is in a deceleration operation state. E
The CU 50 makes this determination based on the idle signal IDL. Here, the throttle valve 24 is fully closed,
When the engine 22 is in the deceleration operation state, the ECU 50 shifts the processing to step 120. Throttle valve 2
4 is opened and the engine 22 is not in the deceleration operation state,
The ECU 50 shifts the processing to step 140.

At the time of deceleration operation of the engine 22, in step 120, the ECU 50 forcibly closes each injector 21 in order to forcibly stop fuel injection to each cylinder of the engine 22, that is, to perform fuel cut. I do.

In step 130, the ECU 50
The fuel cut flag XFC is set to "1" to indicate that the fuel cut is being executed, and the subsequent processing is temporarily ended.

When the engine 22 is not in the deceleration operation state,
In step 140, the ECU 50 sets the fuel cut flag X to indicate that the fuel cut has not been executed.
Set FC to "0".

In step 150, the ECU 50 calculates the value of the basic injection amount TAUb based on the values of the engine speed NE and the intake pressure PM. This basic injection amount TA
Ub is a value in units of time. The ECU 50 calculates the value of the basic injection amount TAUb by referring to predetermined function data using the engine speed NE and the intake pressure PM as parameters.

In step 160, the ECU 50 calculates the value of the temperature correction coefficient KTH based on the value of the cooling water temperature THW. The ECU 50 calculates the value of the temperature correction coefficient KTH by referring to predetermined function data using the coolant temperature THW as a parameter.

At step 170, the ECU 50 calculates the final value of the fuel injection amount TAU by multiplying the value of the basic injection amount TAUb by the temperature correction coefficient KTH. The fuel injection amount TAU is a value in units of time, and is a value that determines the valve opening time of the injector 21.

In step 180, the ECU 50
It is determined whether fuel injection timing has come for each cylinder. The ECU 50 determines the arrival of the injection timing based on a pulse signal related to the engine speed NE.

When the injection timing has arrived, in step 190, the ECU 50 determines the calculated fuel injection amount T
Fuel injection is executed by opening each injector 21 for a required time based on the value of AU. After ending this processing, the ECU 50 once ends the subsequent processing.

FIGS. 3 and 4 are flowcharts showing a "fuel supply control routine" relating to the processing contents of the fuel supply control. The ECU 50 periodically executes this routine at predetermined time intervals when the engine 22 is operating.

In step 200, the ECU 50 reads as input values various parameters IDL, PF, NE and PM detected by the various sensors 45 to 47 and 49. At the same time, the ECU 50 sets the fuel cut flag XF set in the aforementioned “fuel injection control routine”.
Read the value of C. The ECU 50 calculates parameters FB1 and KG for calculating the voltage to be supplied to the pump 12.
1 and FB2 are read. Parameters FB1 and FB2 are feedback values, and parameter KG1 is a learning value. As the feedback values FB1 and FB2, values calculated in the previous routine of the “fuel supply routine” are stored in the RAM in the ECU 50 in advance, and similarly, the learning value KG1 is also the same as that of the “fuel supply routine”. The value calculated in the previous routine is stored in the backup RAM in the ECU 50 in advance. Note that the initial values of the feedback values FB1, FB2 and the learning value KG1 are “0”.

In step 210, the ECU 50 determines whether or not the fuel cut flag XFC is "1". If the flag XFC is “1”, the fuel is cut in the fuel injection control and the engine 22 is in the deceleration operation state.
Move to 0. Then, in step 220, EC
U50 stops the pump 12 and
To stop the suction and discharge of the fuel, and then temporarily end the subsequent processing.

On the other hand, when the flag XFC is "0", the fuel cut is not performed in the fuel injection control, and the engine 22 is in the constant speed operation state or the acceleration operation state. Step 230
Move to.

In step 230, the ECU 50
The detected current fuel pressure PF is equal to the previous fuel pressure PFO.
It is determined whether it is equal to or not. Here, the fuel pressure PFO
Means the fuel pressure detected in the previous routine. That is, in this process, it is determined whether or not the fuel pressure PF has changed from the previous routine. Current fuel pressure PF
Is equal to the previous fuel pressure PFO, the ECU 50
The processing shifts to step 290, and if the current fuel pressure PF is not equal to the previous fuel pressure PFO, the ECU 50
Shifts the processing to step 240.

In step 240, the ECU 50
The target fuel pressure TPF required by the engine 22 is calculated based on the read parameters NE and PM.
The ECU 50 calculates the value of the target fuel pressure TPF by referring to predetermined function data using the engine speed NE and the intake pressure PM as parameters.

In step 250, the ECU 50
Based on the engine speed NE and the intake pressure PM, the intake air amount QA to be taken into each cylinder of the engine 22 is calculated.
The ECU 50 calculates the value of the intake air amount QA by referring to predetermined function data using the engine speed NE and the intake pressure PM as parameters. Generally, the calculated intake air amount QA is appropriately corrected according to the intake air temperature or the like.

Then, at step 260, the ECU
50 calculates a target fuel amount QF to be discharged by the pump 12, based on the engine speed NE and the intake air amount QA calculated in step 250. The ECU 50 compares the value of the target fuel amount QF with the engine speed NE and the intake air amount QA.
Is calculated with reference to function data determined in advance as a parameter.

In step 270, the ECU 50
Based on the fuel amount QF calculated in step 260, a flow rate range RQF to which the fuel amount QF belongs is calculated. This flow rate range RQF is obtained by dividing the total fuel quantity QF that can be discharged by the pump 12 into a plurality of ranges.

At step 280, the ECU 50
A learning value KG2 corresponding to the flow rate range RQF calculated in step 270 is calculated. The learning value KG2 is set for each of the divided flow rate ranges RQF.

Step 280 or the above step 23
0, and at step 290, the ECU 50
Calculates the pump voltage VFP supplied to the pump 12 to obtain the target fuel pressure TPF based on the following equation (1).

VFP = (K1 + FB1 + KG1) + QF * (K2 * FB2 + KG2) (1) The pump voltage VFP is determined by the offset voltage for discharging the minimum fuel amount by the pump 12 and the fuel amount. And a variable voltage for increasing and decreasing.

Here, the relationship between the fuel amount QF and the pump voltage VFP is shown in the graph of FIG. 7, and the relationship of the above equation (1) will be described in detail. As shown in the figure, the pump voltage VFP increases exponentially with respect to the fuel amount QF. If the fuel pressure is constant, ideally the pump voltage VFP
Is directly proportional to the fuel amount QF, but in fact, due to the pressure loss generated in the fuel line 17 and the filter 19, the pump voltage VFP has a relationship as shown in the graph of FIG. This pressure loss increases in proportion to the square of the fuel amount QF. The flow rate range RQF is set in the manner shown in FIG. 7 with respect to the fuel amount QF, and here is divided into six flow rate ranges A to F with an equal width.

The above-described offset voltage is equal to the target fuel amount QF
Regardless, as in the first term of the above equation (1), it is calculated as the sum of the base voltage K1, the feedback value FB1, and the learning value KG1. When the amount of fuel discharged by the pump 12 is minimum, as in the idle operation of the engine 22, the pump voltage VFP is set to the offset voltage. This offset voltage is corrected to increase or decrease based on the feedback value FB1 and the learning value KG1 with reference to the base voltage K1.

On the other hand, the variable voltage includes the fuel amount QF and the constant K
2. It is calculated based on the feedback value FB1 and the learning value KG2 as in the second term of the above equation (1). Further, the variable voltage takes a value proportional to the target fuel amount QF, and is increased or decreased by the feedback value FB2 and the learning value KG2.
Further, as described above, the learning value KG2 is provided for each of the flow ranges A to F, and the learning value KG2 is set to “0” in a state where the above-described aging does not occur in the fuel supply system. Is set.

After calculating the pump voltage VFP, step 30
At 0, the ECU 50 drives the pump 12 by applying the pump voltage VFP to the pump 12.
The amount of fuel discharged by the pump 12 is adjusted according to the magnitude of the pump voltage VFP.

Next, the ECU 50 shifts the processing to step 310 shown in FIG. 4, and determines whether or not the engine 22 is in an idling operation state. The ECU 50 makes this determination based on the idle signal IDL. When the engine 22 is in the idling operation state, the ECU 50 shifts the processing to step 320. If the engine 22 is not in the idling operation state, the ECU 50 proceeds to step 3
Go to 60.

When the engine 22 is in the idling operation state, in step 320, the ECU 50 determines whether the detected actual fuel pressure PF is equal to the target fuel pressure T.
It is determined whether it is the same as the PF. Both PF, TPF
Are the same, the ECU 50 once ends the subsequent processing. If the PF and TPF are different, the ECU 50 shifts the processing to step 330.

In step 330, the ECU 50
It is determined whether or not the actual value of the fuel pressure PF is higher than the target fuel pressure TPF. The fuel pressure PF is equal to the target fuel pressure T
If less than PF, at step 340, EC
U50 increases the feedback value FB1 and temporarily ends the subsequent processing. On the other hand, if the fuel pressure PF is larger than the target fuel pressure TPF, the routine proceeds to step 350.
In, the ECU 50 decreases the feedback value FB1 and temporarily ends the subsequent processing. That is, in steps 320 to 350, the ECU 50 increases or decreases the feedback value FB1 related to the offset voltage so that the actual value of the fuel pressure PF in the idle operation state matches the calculated target fuel pressure TPF.

On the other hand, if the engine 22 is not in the idling state, the process proceeds from step 310 to step 360
, The ECU 50 determines the actual fuel pressure P
It is determined whether or not the value of F is the same as the calculated target fuel pressure TPF. When both PF and TPF are the same, ECU
50 temporarily ends the subsequent processing. Both PF, TPF
Are different, the ECU 50 shifts the processing to step 370.

In step 370, the ECU 50 determines whether the actual value of the fuel pressure PF is higher than the target fuel pressure TPF. The fuel pressure PF is equal to the target fuel pressure TP
If it is smaller than F, the ECU proceeds to step 380 in which the ECU
50 increases the feedback value FB2 and temporarily ends the subsequent processing. On the other hand, if the fuel pressure PF is higher than the target fuel pressure TPF, in step 390, the ECU 50 decreases the feedback value FB2 and temporarily ends the subsequent processing. That is, step 36
From 0 to 390, the ECU 50 determines the actual fuel pressure PF
The feedback value FB2 related to the variable voltage is increased / decreased so that the value of the target fuel pressure TPF matches the calculated target fuel pressure TPF.

Next, a "learning routine" relating to the pump voltage VFP will be described with reference to FIGS. FIG.
9 is a flowchart showing a “learning routine” for calculating an offset voltage. The ECU 50 controls the engine 2
This routine is periodically executed at predetermined intervals during the operation of Step 2.

First, at step 400, the ECU 5
0 is the current feedback value FB1 and the learning value KG1
Read. In step 410, the ECU 50
It is determined whether the current feedback value FB1 is the same as the previous feedback value FB1O. Here, the feedback value FB1O means a value calculated in the previous fuel supply control routine. Current feedback value FB
If 1 is the same as the previous feedback value FB1O, EC
U50 temporarily ends the subsequent processing. On the other hand, when both FB1 and FB1O are different, the ECU 50
The process moves to step 420.

In step 420, the ECU 50
It is determined whether the current feedback value FB1 is larger than the previous feedback value FB1O. If the current feedback value FB1 is larger than the previous feedback FB1O, in step 430, the ECU 50
Increases the learning value KG1 and temporarily ends the subsequent processing. On the other hand, if the current feedback value FB1 is smaller than the previous feedback FB1O, in step 440, the ECU 50 decreases the learning value KG1 and temporarily ends the subsequent processing. That is, in steps 410 to 440, the ECU 50 increases or decreases the value of the learning value KG1 related to the offset voltage according to the increasing tendency or the decreasing tendency of the feedback value FB1.

FIG. 6 is a flowchart showing a "learning routine" for calculating a variable voltage. ECU
50 periodically executes this routine at predetermined intervals when the engine 22 is operating.

First, at step 500, the ECU 5
0 is the flow range RQF, the current feedback value FB
2 and the learning value KG2 are read. In step 510, the ECU 50 determines whether the current feedback value FB2 is the same as the previous feedback value FB2O. Here, the feedback value FB2O means a value calculated in the previous fuel supply control routine. The current feedback value FB2 is equal to the previous feedback value FB.
If it is the same as 2O, the ECU 50 once ends the subsequent processing. On the other hand, when both FB2 and FB2O are different, ECU 50 shifts the processing to step 520.

In step 520, the ECU 50
It is determined whether the current feedback value FB2 is larger than the previous feedback value FB2O. If the current feedback value FB2 is larger than the previous feedback FB2O, in step 530, the ECU 50
Increases the learning value KG2 corresponding to the flow rate range RQF, and temporarily ends the subsequent processing. On the contrary,
If the current feedback value FB2 is smaller than the previous feedback FB2O, in step 540,
The ECU 50 decreases the learning value KG1 corresponding to the flow rate range RQF, and temporarily ends the subsequent processing. That is, in steps 510 to 540, the ECU 50
The value of the learning value KG2 related to the variable voltage is increased or decreased according to the increasing tendency or the decreasing tendency of the feedback value FB2.

The operation of the apparatus having the above-described control structure according to this embodiment will be described below with reference to FIGS. 8 and 9. In the device of this embodiment, the fuel in the tank 11 is pumped to the respective injectors 21 by the pump 12, and the fuel is supplied from the injectors 21 to the respective cylinders of the engine 22. . Here, in the fuel injection control, the ECU 50 controls the engine 2
The fuel injection amount TAU is calculated based on the operation state 2 and the valve opening time of the injector 21 is adjusted based on the fuel injection amount TAU. Further, the ECU 50 calculates a target fuel pressure TPF according to the operating state of the engine 22, and performs feedback control of the driving force of the pump 12 such that the actual fuel pressure PF matches the target fuel pressure TPF. At this time, if the relationship between the fuel amount QF and the pump voltage VFP is the initial characteristic shown by the solid line in FIG. 8, that is, if the fuel supply system does not change over time, the learning value KG1 related to the calculation of the pump voltage VFP is obtained. , KG2 are set to “0”.

Here, if the fuel supply system changes over time, for example, the filter 19 becomes clogged or the pressure loss changes in the fuel line 17, the relationship between the fuel amount QF and the pump voltage VFP changes from the solid line in FIG. It may change as shown in In this case, since the characteristic of the fuel amount QF discharged from the pump 12 is deviated from the initial state, even if the calculated pump voltage VFP is applied to the pump 12, the desired fuel amount QF
F or the fuel pressure TPF becomes difficult to obtain.

If such aging does not occur, a predetermined fuel amount QF1 is obtained by applying a predetermined pump voltage VFP1 to the pump 12. However, when the pressure loss increases due to aging, in order to obtain a desired fuel amount QF1, a pump voltage VFP2 larger by the pressure loss must be applied to the pump 12. Similarly, the fuel pressure P
When increasing F, the fuel amount QF is required to be increased by the pressure loss. Accordingly, the calculated predetermined pump voltage V
FP1 is increased and corrected by the feedback value FB2. Therefore, the value of the feedback value FB2 naturally increases, and the period during which the feedback value FB2 tends to increase also becomes longer. As described above, when the feedback value FB2 is increasing, the value of the learning value KG2 corresponding to the fuel amount QF is increased, and the learning value KG2 is added to the pump voltage VFP. Similarly, when the feedback value FB2 is in a decreasing trend, the value of the learning value KG2 corresponding to the fuel amount QF is reduced, and the learning value KG2 is subtracted from the pump voltage VFP.

The learning value KG2 is learned for each of the flow ranges A to F, and as the learning is continued, finally, the characteristic deviation between the fuel amount QF and the pump voltage VFP becomes equal to the learning value GK2. Will be supplemented. For this reason, the value of each learning value KG2 has a step shape shown in FIG. 8 so as to compensate for the pressure loss corresponding to the flow rate QF.

Therefore, in calculating the pump voltage VFP based on the above equation (1), the value of the feedback value FB2 is set to be small by the amount of the learning value KG2, and the amount of fuel discharged from the pump 12 (fuel pressure PF ) Is the target value Q
It quickly converges to F (fuel pressure TPF).
This learning value KG2 is stored in the backup RAM in the ECU 50.
Therefore, the value is retained even after the engine 22 is stopped, and is used for the next calculation of the pump voltage VFP.

On the other hand, the learning regarding the offset voltage is performed during the idling operation of the engine 22. The feedback value FB1 is calculated based on the pressure difference between the fuel pressure TPF required during the idling operation and the actual fuel pressure PF, and the learning value KG1 is increased or decreased according to the increasing tendency or the decreasing tendency of the feedback value FB1. You. Since the learned value KG1 is used when calculating the pump voltage VFP, a difference in characteristics between the fuel amount QF and the pump voltage VFP due to the aging is compensated.

Therefore, since the offset voltage is also corrected by the learning value KG1, the desired fuel amount QF (fuel pressure TPF) can be quickly obtained in all the flow ranges RQF including the idling operation.

Next, with reference to FIGS. 9A to 9F, the operation relating to the fuel supply control of the apparatus of this embodiment will be described in further detail. FIGS. 9A to 9F show the fuel pressure TP when the engine 22 shifts from the idling operation state to the acceleration operation state.
6 is a timing chart showing changes in F, PF, feedback values FB1, FB2, and learning values KG1, KG2.

In the figure, the engine 22 is in an idle operation state before time t2, and shifts to an acceleration operation state from time t2. As shown in FIG. 9A, when the engine 22 is in the idling operation state, the target fuel pressure T
PF is set to a predetermined value PF1, and when the engine 22 is in the accelerating operation state, the target fuel pressure TPF becomes the predetermined value PF2.
Is set to In this case, the fuel amount QF is increased to increase the actual fuel pressure PF. Here, it is assumed that the fuel amount QF shifts from the flow rate range A to the flow rate range F. Hereinafter, for convenience, the learning value K corresponding to the range F will be described.
G2 is written as KG2F. It is assumed that the learning value KG2F in the timing chart is set to a predetermined value due to the above-described characteristic shift of the fuel supply system. Further, the learning value K in the idling operation state
It is assumed that G1 is set to “0”.

Before the time t1, the actual fuel pressure P
F is equal to the target fuel pressure TPF, and the feedback value FB1 during the idling operation is set to “0”.

Here, at time t1, the filter 19
When the pressure loss increases due to factors such as clogging, the fuel pressure PF decreases by the increase in the pressure loss. As a result, a pressure difference is generated between the actual fuel pressure PF and the target fuel pressure TPF, and the feedback value FB1 is determined according to the pressure difference.
Is calculated. If the feedback value FB1 tends to increase or decrease, the learning value KG1 increases or decreases accordingly.

With this feedback control, the fuel pressure PF becomes equal to the target fuel pressure TPF. At this time, as the feedback value FB1 increases or decreases, the value of the learning value KG1 increases from “0” to a predetermined value α having a positive value. Therefore, since the voltage obtained by adding the predetermined value α of the learning value KG1 to the base voltage K1 is set as the offset voltage, the increase in the pressure loss is supplemented by the learning value KG1. Thereafter, when calculating the pump voltage VFP regardless of the fuel amount QF, the predetermined value α is added.

On the other hand, when the engine 22 shifts to the acceleration operation state at the time t2, the ECU 50 calculates the target fuel pressure TPF and also calculates the fuel amount QF for obtaining the fuel pressure TPF. At this time, the target fuel pressure TPF immediately increases to a predetermined value PF2, and a pressure difference occurs between the actual fuel pressure PF and the target fuel pressure TPF.
In order that the actual fuel pressure PF matches the target value TPF,
A feedback value FB2 according to the differential pressure is calculated,
It is supplied to the pump 12. At this time, the target fuel amount QF
Is included in the flow rate range F, the learning value KG2F corresponding to the flow rate range F is used for calculating the pump voltage VFP. If the feedback value FB2 tends to increase, the learning value KG2 increases, and the feedback value FB2
Is decreasing, the learning value KG2 decreases. In this embodiment, since the learning value KG2F is set to a predetermined value in advance, the learning value KG2F is used for calculating the pump voltage VFP in addition to the feedback value FB2.
As described above, the feedback value FB2 and the learning value KG
2, the pump voltage VFP is corrected to increase or decrease, so that the feedback value FB2 quickly converges, and at time t3, the fuel pressure TPF matches the target value PF2.

That is, at this time, when the pump voltage VFP is calculated, both learning values KG1 and KG2 are added.
The magnitude of the feedback value FB2 is accordingly reduced. Therefore, the amount of overshoot of the fuel pressure PF with respect to the target value PF2 is reduced, and the fuel pressure PF is set to the target value PF2 as compared with the conventional device that does not perform learning (indicated by a dashed line in FIGS. 9D and 9F, respectively). Until it converges quickly.

As described above, even if the characteristics related to the fuel amount QF deviate due to aging, the deviation is corrected by the learning values KG1 and KG2, and the responsiveness and controllability of the pump 12 are ensured. be able to.

Further, in this embodiment, even if there is a slight individual difference in the fuel discharge performance of the pump applied to the fuel supply device, or even if there is a slight individual difference in the piping such as the fuel line. Since the individual difference is a deviation from the characteristic designed in advance, it is compensated by the learning values KG1 and KG2 in the same manner as compensating for the aging of the fuel supply system. Therefore, desired performance can be obtained even if individual pumps, fuel lines, and the like to be manufactured have individual differences.

As described in detail above, according to the fuel supply device of this embodiment, the following excellent effects can be obtained. The responsiveness and controllability of the pump 12 can be ensured even if the pump 12 changes over time.

The pump voltage VF is determined by the learning values KG1 and KG2.
The convergence of the feedback value FB2 and the fuel pressure PF can be improved by the amount by which P is corrected. -Desired performance can be obtained even if there is an individual difference in the pump 12 and the like constituting the fuel supply system.

Since the learning value KG2 is set for each of the flow ranges A to F, the pump voltage VFP can be appropriately increased or decreased according to the fuel amount QF. The values of the learned values KG1 and KG2 once learned are retained in the ECU 50 even after the engine 22 is stopped, so that it is possible to cope with aging related to the fuel supply system.

Since the driving force of the pump 12 is controlled in accordance with the operation state of the engine 22, the durability of the pump 12 can be improved as compared with a device that always drives the pump at full load.

Each of the above embodiments can be embodied in the following other embodiments. In the following another embodiment, the same operation and effect as the above embodiment can be obtained.

In the above embodiment, the fuel flow rate range R
Although the QFs are equally divided, the width of each of the flow ranges A to F may be changed according to the flow rate QF as illustrated in FIG. As described above, in consideration of the relationship that the voltage VFP increases exponentially with respect to the flow rate QF, the width of each of the flow ranges A to F may be reduced as the flow rate QF increases. By setting the flow ranges A to F in this manner, the learning value KG2 is set finely in the flow ranges A to F where the change in the voltage VFP is large.

During the actual operation of the engine, the width of the frequent flow range may be set small, and the width of the frequent flow range may be set wide. Alternatively, the flow rate QF
May be divided more finely than a flow range with a large flow rate QF.

In the above embodiment, the flow rate range RQF is set to 6
Divided into two flow ranges A to F, the flow range RQF
May be divided into seven or more flow ranges or five or less flow ranges.

[0086]

According to the first aspect of the present invention, the responsiveness and controllability of the pump can be ensured and the desired fuel pressure for the internal combustion engine can be maintained even if the characteristics related to the fuel discharge amount change over time. Can be supplied relatively quickly.

According to the second aspect of the present invention, the value of the learning value is increased or decreased so that the feedback value is decreased, and even if the characteristic related to the fuel discharge amount of the pump changes over time, the characteristic is maintained. The convergence of the fuel pressure can be ensured by being appropriately corrected by the learning value.

According to the third aspect of the present invention, since the characteristic relating to the fuel discharge amount is appropriately corrected by the learning value set for each flow rate region, the responsiveness and controllability of the pump in the entire flow rate range are improved. Can be secured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a fuel supply device according to one embodiment of the present invention.

FIG. 2 is a flowchart showing a fuel injection control procedure of the embodiment.

FIG. 3 is a flowchart showing a fuel supply control procedure of the embodiment.

FIG. 4 is a flowchart showing a fuel supply control procedure.

FIG. 5 is a flowchart showing a learning procedure of a learning value KG1.

FIG. 6 is a flowchart showing a learning procedure of a learning value KG2.

FIG. 7 is a graph showing a relationship between a fuel amount, a flow rate range, and a pump voltage.

FIG. 8 is a graph showing a relationship among a fuel amount, a flow rate range, a pump voltage, and a learned value.

FIG. 9 is a timing chart showing a fuel supply control mode of the embodiment.

FIG. 10 is a graph showing another example of dividing the flow rate range.

[Explanation of symbols]

11: fuel tank, 12: fuel pump, 17: fuel line, 19: filter, 22: gasoline engine as internal combustion engine, 46: fuel pressure sensor, 50: electronic control unit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 37/00 F02M 37/00 A

Claims (3)

[Claims] 1. A fuel supply device for an internal combustion engine, wherein a fuel in a fuel tank is suctioned and discharged by a pump and a driving force of the pump is controlled to adjust a fuel pressure supplied to the internal combustion engine. Operating state detecting means for detecting an operating state of the internal combustion engine; and a feedback value of a driving force of the pump so that a fuel pressure supplied to the internal combustion engine becomes a target fuel pressure according to the detected operating state. Feedback value calculating means for calculating a learning value for compensating for a deviation in the characteristic relating to the fuel discharge amount of the pump; and A fuel supply device for an internal combustion engine, comprising: pump control means for controlling a driving force of a pump. 2. The fuel supply device for an internal combustion engine according to claim 1, wherein the learning unit increases or decreases the learning value based on a transition tendency of the calculated feedback value so that the feedback value is reduced. A fuel supply device for an internal combustion engine, comprising: 3. The fuel supply device for an internal combustion engine according to claim 1, wherein the fuel flow rate range of the pump is divided into a plurality of ranges, and the learning value is increased or decreased for each flow rate range. Engine fuel supply.