JP5577310B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel supply control device for an internal combustion engine, and more particularly to a technique for determining an abnormality of a means for detecting an actual fuel pressure in a fuel pipe.

  In Patent Document 1, a feedback control amount for controlling the fuel pump is set based on a deviation between the actual fuel pressure in the fuel pipe and the target fuel pressure, and a change obtained by subtracting the minimum value from the maximum value of the actual fuel pressure. A fuel supply device for an internal combustion engine is disclosed in which an abnormality of a sensor that detects an actual fuel pressure is determined based on an amount or an integrated value of a change amount of a feedback control amount.

Japanese Patent No. 4193331

  However, when determining an abnormality of the fuel pressure sensor based on the change amount obtained by subtracting the minimum value from the maximum value of the actual fuel pressure or the integrated value of the change amount of the feedback control amount, a stack abnormality such as a short circuit can be determined, but the fuel Temporary abnormalities such as noise superimposed on the pressure sensor output cannot be detected. For this reason, when a temporary abnormality occurs, the fuel pump may be controlled based on a sensor output different from the actual fuel pressure.

  Accordingly, an object of the present invention is to provide a fuel supply control device for an internal combustion engine that can detect a temporary abnormality of a means for detecting a fuel pressure in a fuel pipe.

Therefore, in the present invention, when the change speed of the fuel pressure detected by the fuel pressure detection means exceeds the first threshold value, the abnormality of the fuel pressure detection means is determined, and the fuel pressure before the change speed exceeds the first threshold value. The amount of operation of the fuel pump is determined based on the detected value, and when the deviation between the fuel pressure detected by the fuel pressure detecting means and the target value falls below the second threshold, the abnormality determination based on the change speed is canceled, When the abnormality determination based on the change speed continues beyond the limit time, the operation amount of the fuel pump is fixed to a predetermined value .

  According to the above invention, a temporary abnormality of the means for detecting the fuel pressure in the fuel pipe can be detected, and it is possible to suppress the fuel pressure from being erroneously controlled based on the temporary abnormality.

1 is a system diagram of an internal combustion engine including a fuel supply control device according to an embodiment of the present invention. It is a flowchart which shows the abnormality determination process of the fuel pressure sensor in embodiment of this invention. It is a time chart which shows the calculation characteristic of the state which noise superimposed on the output of the fuel pressure sensor in embodiment of this invention, and an output variation | change_quantity.

Embodiments of the present invention will be described below.
FIG. 1 is a system configuration diagram of a fuel supply control apparatus for an internal combustion engine according to the present invention.
In FIG. 1, an internal combustion engine (engine) 1 for a vehicle includes a fuel injection valve 3 in an intake passage (intake port) 2, and the fuel injection valve 3 injects fuel into the intake passage (intake port) 2. .

The fuel injected by the fuel injection valve 3 is sucked into the combustion chamber 5 together with air when the intake valve 4 is opened in the intake stroke, and is ignited and combusted by spark ignition by the spark plug 6. The combustion gas in the combustion chamber 5 is discharged into the exhaust passage 8 when the exhaust valve 7 is opened in the exhaust stroke.
An electronic control throttle 10 that is opened and closed by a throttle motor 9 is provided upstream of the portion of the intake passage 2 where the fuel injection valve 3 is disposed. The amount of intake air is adjusted.

In addition, a fuel supply device 13 is provided for pumping the fuel in the fuel tank 11 to the fuel injection valve 3 (internal combustion engine 1) by the fuel pump 12.
The fuel supply device 13 includes a fuel tank 11, a fuel pump 12, a fuel gallery pipe 14, and a fuel supply pipe 15.

The fuel pump 12 is an electric pump that rotationally drives a pump impeller with a motor, and is disposed in the fuel tank 11.
One end of the fuel supply pipe 15 is connected to the discharge port of the fuel pump 12, the other end of the fuel supply pipe 15 is connected to the fuel gallery pipe 14, and the fuel supply port of the fuel injection valve 3 is connected to the fuel gallery pipe 14. Connected.

  A pressure regulator that opens when the fuel pressure in the fuel supply pipe 15 exceeds a predetermined minimum pressure and returns the fuel in the fuel supply pipe 15 into the fuel tank 11 through the orifice, or the pressure regulator. There may be provided a jet pump for transferring the fuel using the flow of fuel returned from the fuel.

An ECM (engine control module) 31 having a microcomputer is provided as a control unit for controlling fuel injection by the fuel injection valve 3, ignition operation by the ignition plug 6, opening of the electronic control throttle 10, and the like.
Further, an FPCM (fuel pump control module) 30 having a microcomputer is provided as a control unit for outputting a drive output signal of the fuel pump 12.

The ECM 31 and the FPCM 30 are configured to be able to communicate with each other, and an instruction signal for driving duty (applied voltage) of the fuel pump 12 is transmitted from the ECM 31 to the FPCM 30.
The driving duty (%) in the present application is an on-time ratio in one cycle, and the larger the driving duty, the higher the applied voltage of the fuel pump 12 and the higher the rotational speed of the fuel pump 12. Is changed to change the discharge amount of the fuel pump 12 and control the fuel pressure (fuel pressure in the fuel pipe) supplied to the fuel injection valve 3.
In addition, one control unit having both the function as the ECM 31 and the function as the FPCM 30 can be provided.

The ECM 31 includes a fuel pressure sensor (fuel pressure detecting means) 33 for detecting an actual fuel pressure FUPR in the fuel gallery pipe 16 (fuel pipe), and an accelerator opening for detecting an accelerator pedal depression amount (accelerator opening) ACC (not shown). A sensor 34, an air flow sensor 35 for detecting the intake air flow rate QA of the internal combustion engine 1, a rotation sensor 36 for detecting the rotational speed NE of the internal combustion engine 1, and a water temperature sensor 37 for detecting the cooling water temperature TW (engine temperature) of the internal combustion engine 1. A detection signal is input from an oxygen sensor 38 that detects a rich / lean RL with respect to the stoichiometric air-fuel ratio (target air-fuel ratio) of the air-fuel ratio of the internal combustion engine 1 in accordance with the oxygen concentration in the exhaust gas.
Instead of the oxygen sensor 38, an air-fuel ratio sensor that generates an output corresponding to the air-fuel ratio may be provided.

The ECM 31 calculates the basic injection pulse width TP based on the intake air flow rate QA and the engine rotational speed NE, and corrects the basic injection pulse width TP according to the actual fuel pressure FUPR at that time, while the output of the oxygen sensor 38 is corrected. Based on this, the air-fuel ratio feedback correction coefficient LAMBDA for approximating the actual air-fuel ratio to the target air-fuel ratio is calculated, and the basic injection pulse width TP corrected according to the actual fuel pressure FUPR is further corrected with the air-fuel ratio feedback correction coefficient LAMBDA. Thus, the final injection pulse width TI is calculated.
At the injection timing of each cylinder, an injection pulse signal having an injection pulse width TI is output to the fuel injection valve 3 to control the fuel injection amount and the injection timing by the fuel injection valve 3.

Further, the ECM 31 calculates an ignition timing (ignition advance value) based on the basic injection pulse width TP indicating the load of the internal combustion engine 1 and the engine speed NE, and spark discharge by the spark plug 6 is performed at the ignition timing. In this manner, the energization to the ignition coil (not shown) is controlled.
Further, the ECM 31 calculates the target opening of the electronically controlled throttle 10 from the accelerator opening ACC or the like, and drives and controls the throttle motor 9 so that the actual opening approaches the target opening.

Further, the ECM 31 calculates a target fuel pressure TGFUPR in the fuel gallery pipe 16 (fuel pipe) based on engine operating conditions (for example, engine load, engine speed, engine temperature, etc.), and the actual pressure detected by the fuel pressure sensor 33 is calculated. For example, the drive duty (operation amount) of the fuel pump 12 is calculated by proportional-integral-derivative control (PID control) based on a deviation between the actual fuel pressure FUPR and the target fuel pressure TGFUPR so that the fuel pressure FUPR approaches the target fuel pressure TGFUPR.
Then, the ECM 31 outputs a signal instructing the calculated drive duty to the FPCM 30, and the FPCM 30 controls on / off of energization to the fuel pump 12 with the instructed drive duty.

As described above, in this embodiment, the ECM 31 has a function as a means for setting the target fuel pressure in the fuel pipe and a means for calculating the operation amount based on the actual fuel pressure and the target fuel pressure. Since the fuel pressure in the fuel pipe is adjusted by changing the discharge amount of 12, the fuel pump 12 corresponds to a means for adjusting the fuel pressure in the fuel pipe in accordance with the operation amount.
Note that the actual fuel pressure FUPR may be brought closer to the target fuel pressure TGFUPR by electronically controlling the amount of fuel relief from the fuel pipe while the applied voltage of the fuel pump 12 is constant. A controllable pressure regulator corresponds to a means for adjusting the fuel pressure in the fuel pipe.

Further, the ECM 31 has functions as means for performing abnormality determination of the fuel pressure sensor 33 (fuel pressure detection means) and means for canceling abnormality determination. Hereinafter, the abnormality determination processing will be described with reference to the flowchart of FIG. It explains in detail according to.
The routine shown in the flowchart of FIG. 2 is executed by the ECM 31 at regular intervals.

In step S101, the output voltage VFP of the fuel pressure sensor 33 is sampled.
The fuel pressure sensor 33 outputs a voltage signal proportional to the actual fuel pressure FUPR in the fuel gallery pipe 16 (fuel pipe). In step S101, the output signal of the fuel pressure sensor 33 is A / D converted. The latest value of the obtained voltage data is sampled, and the latest sampled voltage data is set to the current value VFP.
In step S101, the current value VFP at the previous execution of this routine is set to the previous value VFPOLD.
The drive duty (operation amount) of the fuel pump 12 is calculated based on the current value VFP (or the actual fuel pressure FUPR obtained by converting the current value VFP).

In step S102 (abnormality determination means), the absolute value (change amount) of the deviation between the current value VFP and the previous value VFPOLD is calculated (change amount calculation means), and the absolute value of the deviation is compared with the first threshold value A. .
When the normal state of the fuel pressure sensor 33 continues, the previous value VFPOLD is the sensor voltage sampled in step S101 at the previous execution of this routine, and is the sensor voltage that has recently been determined to be normal.
Therefore, in step S102, the latest sensor voltage change amount (deviation) from the reference voltage (normal sensor voltage) is compared with the first threshold A based on the sensor voltage that has recently been determined to be normal. become.

  Note that the output voltage VFP of the fuel pressure sensor 33 may be converted into the actual fuel pressure FUPR, and the amount of change in the actual fuel pressure FUPR may be calculated as the deviation between the current value and the previous value of the actual fuel pressure FUPR. If the normal state of the fuel pressure sensor 33 continues, the previous value VFPOLD is the sensor voltage sampled in step S101 during the previous execution of this routine. The value is the change amount of the sensor voltage per execution cycle of this routine, and indicates the change speed of the sensor voltage.

The first threshold value A is a value that does not reach when the fuel pressure sensor 33 is in a normal state when the drive duty (operation amount) of the fuel pump 12 is controlled so that the actual fuel pressure FUPR approaches the target fuel pressure TGFUPR. It is set to a value exceeding the first time when an abnormality such as noise is superimposed on the output of the fuel pressure sensor 33.
That is, even if the maximum change rate of the discharge amount of the fuel pump 12, the maximum or minimum fuel consumption amount in the internal combustion engine 1, the pulsation of the fuel pressure accompanying fuel injection, and the like are taken into account, the change amount of the fuel pressure in the fuel pipe is The first threshold value A is set to a value that does not exceed.

Therefore, when the absolute value of the deviation between the current value VFP and the previous value VFPOLD exceeds the first threshold A, that is, when the output of the fuel pressure sensor 33 suddenly changes from the normal level, the output of the fuel pressure sensor 33 is For example, it can be determined that this is a temporary abnormal state in which noise is superimposed or the like, and a change at the rising or falling part of the noise is detected.
That is, in FIG. 3, when noise occurs at time T1, the output voltage of the fuel pressure sensor 33 changes suddenly, so the absolute value of the deviation between the current value VFP and the previous value VFPOLD is compared with the first threshold A. Thus, a temporary abnormality of the fuel pressure sensor 33 can be accurately detected.
On the other hand, when the absolute value of the deviation between the current value VFP and the previous value VFPOLD is equal to or less than the first threshold value A, that is, when the output of the fuel pressure sensor 33 is stable near the normal level, the fuel pressure sensor 33. It can be determined that the fuel pressure sensor 33 is in a normal state in which no temporary abnormality such as noise is superimposed on the output of the fuel.

Therefore, if it is determined that the absolute value of the deviation between the current value VFP and the previous value VFPOLD exceeds the first threshold value A, the process proceeds to step S104, and the flag FLGFP indicating whether or not the fuel pressure sensor 33 is determined to be abnormal is determined. “1” indicating the state is set.
It should be noted that the initial value of the flag FLGFP is zero, and in the abnormality determination state where the flag FLGFP = 1, the warning of the fuel pressure sensor 33 (fuel supply system) is given to the vehicle driver by turning on the warning lamp 39 or the like. Can be warned.

In step S104, an update process for setting the previous value VFPOLD, that is, the output voltage of the fuel pressure sensor 33 at the previous execution of this routine, to the current value VFP set in step S101 is performed.
Since the sensor voltage was normal until the previous time and the voltage sampled this time was an abnormal value (noise component), if the absolute value (change amount) of the deviation between the current value VFP and the previous value VFPOLD exceeds the first threshold A, When the drive duty (operation amount) of the fuel pump 12 is calculated based on the sensor voltage (noise component) sampled this time, the drive duty (operation amount) is calculated based on a pressure different from the actual fuel pressure. Thus, the actual fuel pressure deviates from the target, and the air-fuel ratio controllability in the internal combustion engine 1 is reduced.

Therefore, in order to calculate the driving duty (operation amount) of the fuel pump 12 based on the previous value VFPOLD which is the last output in the normal state of the fuel pressure sensor 33, the output voltage (sampled this time) with respect to the current value VFP ( Instead of the noise component), the output voltage of the fuel pressure sensor 33 at the previous execution of this routine, in other words, the output voltage in the normal state is set.
Thus, if it is determined that the output voltage sampled this time is a noise component, the output voltage at the previous execution of this routine, which is the output in the normal state, is set to the current value VFP. Although the previous value is actually a noise component, the normal value is set as the previous value VFPOLD. Therefore, at the next execution of this routine, in step S102, the latest change amount of the output voltage with respect to the output voltage in the normal state is calculated.

Then, when it is determined that the absolute value of the deviation between the current value VFP and the previous value VFPOLD exceeds the first threshold value A next time, the process proceeds to step S104. Since the normal value is set to the current value VFP instead of the output voltage that is a noise component, the drive duty of the fuel pump 12 (continuously based on the output voltage in the normal state) is set. Operation amount) is calculated.
For example, as shown in FIG. 3, when it is determined that the absolute value of the deviation between the current value VFP and the previous value VFPOLD exceeds the first threshold A at the time T1, the current value VFP at the time T1 is Instead of the sampling value at the time point T1, the sampling value at the previous time point T0 is set.

At the next time T2, the current value VFP is set to the previous value VFPOLD at the time T1, but since the sampling value at the time T0 is set as the current value VFP at the time T1, the time V2 is set at the time T2. Is also set to the sampling value at time T0, that is, the output voltage immediately before the occurrence of the abnormality.
Even at time T2, if it is determined that the absolute value of the deviation between the current value VFP and the previous value VFPOLD exceeds the first threshold A, the current value VFP at time T2 is changed to the sampling value at time T2. Instead, the sampling value at the time of T0 immediately before is set.

  Therefore, while the output voltage is abnormal, the drive duty (operation amount) of the fuel pump 12 is calculated based on the output voltage immediately before the occurrence of the abnormality (at time T0 in FIG. 3), and noise components and the like are calculated. It is possible to prevent the drive duty (operation amount) from being calculated based on the abnormal output. Thereby, the actual fuel pressure can be stabilized near the target, and the control accuracy of the air-fuel ratio in the internal combustion engine 1 can be maintained.

On the other hand, if it is determined in step S102 that the absolute value of the deviation between the current value VFP and the previous value VFPOLD is less than or equal to the first threshold value A, the process proceeds to step S103.
In step S103, it is determined whether or not the flag FLGFP = 1. If the flag FLGFP = 0 and the fuel pressure sensor 33 is in the normal determination state, the state of the flag FLGFP = 0 is continued and the latest sampling is performed. Since the drive duty (operation amount) of the fuel pump 12 may be calculated based on the sensor voltage VFP, the process proceeds to step S108.
On the other hand, if the flag FLGFP = 1 and the abnormality of the fuel pressure sensor 33 is determined, the step S104 is the same as the case where it is determined in step S102 that | VFP−VFPOLD |> A. Proceed to

In the abnormality determination state that has proceeded to step S104, the process proceeds to step S105 to determine whether or not the abnormality determination can be canceled.
In step S105, the absolute value of the deviation between the actual fuel pressure FUPR (actual fuel pressure FUPR obtained by converting the latest output of the fuel pressure sensor 33) and the target fuel pressure TGFUPR is calculated (deviation calculating means), and the absolute value of this deviation is calculated. It is determined whether or not the state below the second threshold B continues beyond the set time tSL.

The second threshold B is a value that is smaller than the absolute value of the deviation when the actual fuel pressure FUPR is stably converged to the target fuel pressure TGFUPR. Depending on the pulsation of the fuel pressure that accompanies fuel injection in the converged state, The absolute value of the deviation is set so as not to exceed.
The set time tSL is the minimum duration of the convergence state in which it can be determined that the convergence state to the target fuel pressure TGFUPR is stable. The set time tSL exceeds the set time tSL (the actual fuel pressure FUPR is equal to the target fuel pressure TGFUPR ± second threshold value). In the case where the state in the range of B continues), it can be determined that the convergence state is stable.
It should be noted that the stability to the convergence state indicates that the convergence state is expected to continue after that time.

Therefore, if the state where the absolute value of the deviation between the actual fuel pressure FUPR and the target fuel pressure TGFUPR is lower than the second threshold B continues for the set time tSL, the actual fuel pressure FUPR stably converges near the target fuel pressure TGUPPR. It can be determined that the user is in a state of being.
If the state where the absolute value of the deviation between the actual fuel pressure FUPR and the target fuel pressure TGFUPR is lower than the second threshold value B continues for the set time tSL, noise may be temporarily superimposed on the output of the fuel pressure sensor 33 or the like. Even if it becomes abnormal, it can be presumed that a continuous convergence state is obtained because the superimposition of noise is stopped and then it is stably returned to the normal level.

On the other hand, if the state where the absolute value of the deviation between the actual fuel pressure FUPR and the target fuel pressure TGFUPR is less than the second threshold B does not continue beyond the set time tSL, the output at that time is assumed to be close to the normal level. However, it cannot be said that the state has been removed from the noise superimposition state. For example, there is a possibility that the sensor output is oscillating with a normal level interposed therebetween.
For this reason, although the absolute value of the deviation between the actual fuel pressure FUPR and the target fuel pressure TGFUPR is greater than or equal to the second threshold value B, or the absolute value of the deviation is less than the second threshold value B, If it is equal to or shorter than the set time tSL, the process proceeds to step S106, where the flag FLGFP = 1, that is, the abnormality determination state of the fuel pressure sensor 33 is continued.

On the other hand, if the state where the absolute value of the deviation between the actual fuel pressure FUPR and the target fuel pressure TGFUPR is lower than the second threshold B continues beyond the set time tSL, it has escaped from a temporary abnormal state such as noise superposition. The process proceeds to step S107 (abnormality determination canceling means), resets the flag FLGFP to zero, and cancels the abnormal determination.
When the abnormality determination is released in this way, the state returns to the state of calculating the drive duty of the fuel pump 12 based on the latest output of the fuel pressure sensor 33, and the fuel pressure can be controlled with high accuracy.

  In addition, after the abnormality determination of the fuel pressure sensor 33 is performed, if the abnormality determination (flag FLGFP = 1) is not canceled even when the cancellation limit time is reached, the abnormality of the fuel pressure sensor 33 is caused by superimposition of noise. Since there is a possibility that it is not a temporary abnormality such as a stack failure (a failure in which the sensor output sticks to the high output side or the small output side), the stack failure is separately determined and the output of the fuel pressure sensor 33 is output. It is preferable to perform a fail process such as stopping the calculation of the driving duty of the fuel pump 12 based on this and fixing the driving duty to a duty set in advance as a value suitable for a stack failure.

In step S108, the drive duty (operation amount) of the fuel pump 12 is calculated based on the current value VFP. Specifically, the actual fuel pressure is detected based on the current value VFP that is the output voltage of the fuel pressure sensor 33, and the drive duty (operation amount) of the fuel pump 12 is calculated so that the actual fuel pressure approaches the target fuel pressure TGFUPR. .
Here, when the process proceeds to step S106 and the flag FLGFP is set to 1, as described above, the most recently determined output voltage is set for the current value VFP, and therefore based on this normal value. The drive duty (operation amount) of the fuel pump 12 can be calculated.

In this case, the current value VFP is not the latest value but the past sensor output value. When the target fuel pressure is stable, the fuel pressure is calculated by calculating the drive duty (operation amount) based on the current value VFP. Sufficient control accuracy can be maintained.
On the other hand, when the target fuel pressure changes, if the past sensor output value is continuously used, the control accuracy of the fuel pressure is lowered. That is, when the target fuel pressure changes, if the past sensor output value is continuously used, the manipulated variable is changed to eliminate the fuel pressure deviation caused by the change in the target fuel pressure, and even if the actual fuel pressure changes, Since the detected value of the fuel pressure used to calculate the manipulated variable does not change, the actual fuel pressure cannot be controlled near the target fuel pressure, and the fuel injection pulse width is corrected based on a pressure different from the actual fuel pressure. May cause misfires and engine stalls.

Therefore, when the target fuel pressure changes, the fuel pressure change is predicted based on the current value VFP based on the reference model of the fuel supply system in consideration of the operation characteristics and phase delay of the fuel pipe and the fuel pump 12, etc. Based on the predicted fuel pressure, the drive duty (operation amount) of the fuel pump 12 can be calculated, or the fuel injection pulse width can be corrected. In this way, even if the target fuel pressure changes, the actual fuel pressure can be controlled close to the target fuel pressure, and the fuel injection pulse width can be corrected substantially according to the actual fuel pressure, thereby suppressing misfires and engine stalls. it can.
On the other hand, when the flag FLGFP = 0 and the fuel pressure sensor 33 is in a normal state, the current value VFP is the latest output value of the fuel pressure sensor 33 and is not the noise component but the actual fuel pressure. Therefore, even if the target fuel pressure changes, the actual fuel pressure is calculated by calculating the drive duty (operation amount) of the fuel pump 12 based on the current value VFP and correcting the fuel injection pulse width. Can be controlled to the target fuel pressure, and the fuel injection pulse width can be corrected according to the actual fuel pressure.

According to the above embodiment, a temporary abnormality of the fuel pressure sensor 33 (fuel pressure detection means) for detecting the fuel pressure in the fuel pipe can be detected, and the fuel pump is based on a detection result different from the actual due to the temporary abnormality. 12 can be prevented from being erroneously calculated, and the control accuracy of the fuel pressure, that is, the deterioration of the air-fuel ratio control accuracy in the internal combustion engine 1 can be suppressed.
Further, since a temporary abnormality of the fuel pressure sensor 33 is detected on the basis of the sensor output at the normal time and based on the change amount of the sensor output from the reference value, the change in the sensor output after the abnormality has occurred is relatively small It is possible to detect the continuation of the abnormality even in the state and to detect the temporary abnormality with high accuracy.

In addition, since the temporary abnormality determination is canceled on the condition that the actual fuel pressure FUPR is stably converged near the target fuel pressure TGFUPR, the abnormality determination can be canceled at an appropriate timing, and the temporary abnormality is removed. Then, it is possible to return to the normal control of the fuel pressure sensor 33 as soon as possible, that is, the calculation of the drive duty of the fuel pump 12 based on the latest output of the fuel pressure sensor 33.
Further, in the abnormality determination period of the fuel pressure sensor 33 (period in which the flag FLGFP = 1), the drive duty (operation amount) of the fuel pump 12 is calculated based on the immediately previous normal output, so that a temporary abnormality occurs. Among these, it is possible to prevent the actual fuel pressure FUPR from deviating from the target fuel pressure TGFUPR due to erroneous control of the fuel pump 12.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 11 ... Fuel tank, 12 ... Fuel pump, 15 ... Fuel gallery piping, 16 ... Fuel supply piping, 30 ... FCM (fuel control module), 31 ... ECM (engine control module), 33 ... Fuel pressure sensor (Fuel pressure detection means)

Claims (3)

Fuel supply for an internal combustion engine comprising fuel pressure detection means for detecting the pressure of fuel pumped from the fuel pump to the internal combustion engine, and controlling the fuel pump based on the fuel pressure detected by the fuel pressure detection means and a target value In the control device,
When the change speed of the fuel pressure detected by the fuel pressure detection means exceeds a first threshold value, an abnormality of the fuel pressure detection means is determined, and the detected value of the fuel pressure before the change speed exceeds the first threshold value is determined. Based on the operating amount of the fuel pump,
Canceling the abnormality determination based on the change speed when the deviation between the fuel pressure detected by the fuel pressure detecting means and the target value falls below a second threshold;
A fuel supply control device for an internal combustion engine , which fixes an operation amount of the fuel pump to a predetermined value when abnormality determination based on the change speed continues beyond a limit time . 2. The fuel supply control device for an internal combustion engine according to claim 1 , wherein the abnormality determination based on the change speed is canceled when the state where the deviation is less than the second threshold continues for a predetermined time . The fuel pressure is predicted based on a reference model of a fuel supply system based on the fuel pressure before the change speed exceeds the first threshold, and the operation amount of the fuel pump is determined based on the predicted fuel pressure. Item 3. A fuel supply control device for an internal combustion engine according to Item 1 or 2.