JP5733161B2 - Fuel injection control system for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection control system for an internal combustion engine.

  An electric fuel pump is known as a pump mechanism that pumps fuel from a fuel tank. As a method for controlling an electric fuel pump, the fuel pump includes an electric fuel pump that pumps up fuel stored in a fuel tank, and a fuel pump driving device that adjusts a voltage supplied from the battery to the fuel pump. A method has been proposed in which the drive device adjusts the amount of fuel discharged from the fuel pump by changing the ratio of the application time of the battery voltage to the fuel pump and the stop time (see, for example, Patent Document 1). .

JP 2008-014183 A JP 09-184460 A JP 2010-077957 A

  An object of the present invention is to provide a technique capable of detecting an abnormality of the system in a fuel injection control system for an internal combustion engine including an electric fuel pump disposed in a fuel path from a fuel tank to a fuel injection valve. And

In order to solve the above-described problem, the present invention provides a fuel injection control system for an internal combustion engine including an electric fuel pump disposed in a fuel path from a fuel tank to a fuel injection valve.
Detecting means for detecting current consumption of the electric fuel pump;
Calculation means for calculating the pressure of fuel discharged from the electric fuel pump, using the current consumption detected by the detection means as a parameter;
Obtaining means for obtaining fuel pressure in a fuel path downstream from the electric fuel pump;
A determination unit that determines that an abnormality has occurred in the system when the difference between the fuel pressure calculated by the calculation unit and the fuel pressure acquired by the acquisition unit exceeds a threshold;
I was prepared to.

  The “abnormality” here includes not only an abnormality caused by a failure of the fuel injection control system but also an abnormality caused by the property of the fuel used being different from the assumed property.

  When clogging or the like occurs in the fuel path downstream from the fuel pump, the fuel pressure acquired by the acquisition unit is lower than the pressure of fuel discharged from the electric fuel pump (discharge pressure). Here, the current (consumption current) flowing through the electric fuel pump is proportional to the torque of the electric fuel pump, in other words, the pressure of the fuel discharged from the electric fuel pump. Therefore, when clogging or the like occurs in the fuel path downstream from the electric fuel pump, the fuel pressure calculated by the calculation unit becomes higher than the fuel pressure acquired by the acquisition unit. In other words, the consumption current of the electric fuel pump is larger than the consumption current corresponding to the fuel pressure acquired by the acquisition means.

Therefore, by comparing the fuel pressure calculated by the calculation means with the fuel pressure acquired by the acquisition means, it is possible to detect an abnormality caused by clogging of the fuel path. In this case, the threshold value may be set, for example, to a value obtained by adding a margin to a minimum value considered that the degree of clogging of the fuel path may deteriorate the combustion stability and exhaust emission of the internal combustion engine.

  Further, when the fuel used in the internal combustion engine is lighter than the fuel assumed in advance (hereinafter referred to as “reference fuel”), the fuel pressure acquired by the acquisition means is compared with the case where the reference fuel is used. Becomes lower. Therefore, the fuel pressure calculated by the calculating means is higher than the fuel pressure acquired by the acquiring means. In other words, the consumption current of the electric fuel pump is larger than the consumption current corresponding to the fuel pressure acquired by the acquisition means.

  On the other hand, when the fuel used for the internal combustion engine is heavier than the reference fuel, the fuel pressure acquired by the acquisition means is higher than when the reference fuel is used. For this reason, the fuel pressure calculated by the calculating means is lower than the fuel pressure acquired by the acquiring means. In other words, the current consumption of the electric fuel pump is less than the current consumption corresponding to the fuel pressure acquired by the acquisition means.

  Therefore, by comparing the fuel pressure calculated by the calculation means with the fuel pressure acquired by the acquisition means, it is possible to detect an abnormality caused by the property of the fuel used being different from the reference fuel. In this case, the threshold value is set to a value obtained by adding a margin to a minimum value considered that the difference between the property of the fuel used and the property of the reference fuel can deteriorate the combustion stability and exhaust emission of the internal combustion engine, for example. May be.

  The threshold value is the minimum value at which the degree of clogging of the fuel path can deteriorate the inflammatory stability and exhaust emission of the internal combustion engine, and the difference between the properties of the fuel used and the properties of the reference fuel is the combustion stability of the internal combustion engine. It may be set to a value obtained by adding a margin to the smallest value among the minimum values that can be considered to deteriorate the exhaust emission.

  Next, the fuel injection control system for an internal combustion engine according to the present invention may further include driving means for driving the electric fuel pump so that the consumption current of the electric fuel pump matches a target value.

  When the flow rate of the fuel changes when the applied voltage of the electric fuel pump is constant, the pressure discharged from the electric fuel pump changes. Therefore, if it is attempted to control the fuel pressure using the applied voltage of the electric fuel pump as a parameter, it is necessary to adjust the applied voltage in accordance with the fuel flow rate.

  On the other hand, even when the flow rate of the fuel changes when the applied current of the electric fuel pump is constant, the pressure discharged from the electric fuel pump becomes substantially constant. Therefore, when the electric fuel pump is driven so that the consumption current of the electric fuel pump converges to the target value, the fuel pressure easily converges to the target value.

A fuel injection control system for an internal combustion engine of the present invention is disposed in a fuel path downstream from an electric fuel pump, and a booster pump that boosts the fuel discharged from the electric fuel pump;
A pressure sensor for detecting a discharge pressure of the booster pump;
A calculation unit for calculating a drive signal of the boost pump using a proportional term and an integral term calculated using a deviation between a target discharge pressure of the boost pump and a detection value of the pressure sensor as a parameter;
Reduction processing means for reducing the target discharge pressure of the electric fuel pump in accordance with the change tendency of the integral term;
You may make it provide.

  A case where a boost pump drive signal is calculated using proportional integral control using a deviation between a target discharge pressure of the boost pump and a detected value of the pressure sensor (hereinafter referred to as “actual discharge pressure”) as a parameter; In addition, when the discharge pressure of the low-pressure fuel pump is continuously or stepwise reduced, if the fuel vapor sucked into the boost pump is generated, the integral term shows an increasing tendency (unit time of the integral term). The amount of change per unit is greater than zero). Therefore, when the integral term shows a constant or decreasing tendency (when the amount of change of the integral term per unit time is less than or equal to zero), the reduction process is executed, and the integral term shows an increasing tendency ( When the increase process is executed when the amount of change in the integral term per unit time is greater than zero, the discharge pressure of the low-pressure fuel pump can be reduced while avoiding the generation of vapor.

  In the fuel injection control system for an internal combustion engine of the present invention, the acquisition means may be a means for measuring the fuel pressure (for example, a pressure sensor), or a means for calculating the fuel pressure using the fuel temperature or the like as a parameter. Also good.

  In the fuel injection control system for an internal combustion engine of the present invention, the current consumption of the fuel pump is converted into fuel pressure, and the presence or absence of abnormality is determined by comparing the fuel pressure with the fuel pressure in the fuel path. However, the presence or absence of abnormality may be determined by converting the fuel pressure acquired by the acquisition means into the consumption current of the fuel pump and comparing the consumption current with the actual consumption current of the fuel pump.

Specifically, the present invention relates to a fuel injection control system for an internal combustion engine including an electric fuel pump disposed in a fuel path from a fuel tank to a fuel injection valve.
Detecting means for detecting current consumption of the fuel pump;
Obtaining means for obtaining fuel pressure in a fuel path downstream from the fuel pump;
Calculation means for calculating the consumption current of the fuel pump, using the fuel pressure acquired by the acquisition means as a parameter;
Determination means for determining that an abnormality has occurred in the system when the difference between the consumption current detected by the detection means and the consumption current calculated by the calculation means exceeds a threshold;
You may make it provide.

  ADVANTAGE OF THE INVENTION According to this invention, in the fuel injection control system of the internal combustion engine which adjusts the discharge pressure of a fuel pump by controlling the drive current of a fuel pump, the abnormality of the said system can be detected.

It is a figure which shows schematic structure of the fuel-injection system of the internal combustion engine to which this invention is applied. It is a figure which shows the behavior of the integral term when the discharge pressure of a low pressure fuel pump is reduced, and the behavior of the fuel pressure in a high pressure fuel passage. It is a figure which shows schematic structure of a drive circuit. It is a figure which shows the relationship between the discharge pressure and fuel flow in case the voltage applied to a low pressure fuel pump is constant. It is a figure which shows the relationship between the discharge pressure and fuel flow in case the electric current applied to a low pressure fuel pump is constant. It is a flowchart which shows the process routine performed when detecting abnormality of a fuel injection control system.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

  FIG. 1 is a diagram showing a schematic configuration of a fuel injection control system for an internal combustion engine according to the present invention. The fuel injection control system shown in FIG. 1 is a fuel injection control system applied to an in-line four-cylinder internal combustion engine, and includes a low-pressure fuel pump 1 and a high-pressure fuel pump 2. Note that the number of cylinders of the internal combustion engine is not limited to four, and may be five or more, or may be three or less.

  The low-pressure fuel pump 1 is an embodiment of an electric fuel pump according to the present invention, and is a pump for pumping up fuel stored in the fuel tank 3. The low-pressure fuel pump 1 is a turbine pump (Wesco pump) driven by electric power. The fuel discharged from the low pressure fuel pump 1 is guided to the suction port of the high pressure fuel pump 2 by the low pressure fuel passage 4.

  The high-pressure fuel pump 2 is an embodiment of a booster pump according to the present invention, and is a pump for boosting the fuel discharged from the low-pressure fuel pump 1. The high-pressure fuel pump 2 is a reciprocating pump (plunger pump) driven by the power of the internal combustion engine (for example, the rotational force of the camshaft). A suction valve 2 a for switching between conduction and blockage of the suction port is provided at the suction port of the high-pressure fuel pump 2. The suction valve 2a is an electromagnetically driven valve mechanism, and changes the discharge amount of the high-pressure fuel pump 2 by changing the opening / closing timing with respect to the position of the plunger. The base end of the high-pressure fuel passage 5 is connected to the discharge port of the high-pressure fuel pump 2. The end of the high pressure fuel passage 5 is connected to a delivery pipe 6.

  Four fuel injection valves 7 are connected to the delivery pipe 6, and high-pressure fuel pumped from the high-pressure fuel pump 2 to the delivery pipe 6 is distributed to each fuel injection valve 7. The fuel injection valve 7 is a valve mechanism that injects fuel directly into the cylinder of the internal combustion engine.

  In addition to the in-cylinder fuel injection valve such as the fuel injection valve 7 described above, a port injection fuel injection valve for injecting fuel into the intake passage (intake port) is attached to the internal combustion engine. If so, the low pressure fuel passage 4 may be branched from the middle to supply the low pressure fuel to the port injection delivery pipe.

  A pulsation damper 11 is disposed in the middle of the low-pressure fuel passage 4 described above. The pulsation damper 11 attenuates fuel pulsation caused by the operation (suction operation and discharge operation) of the high-pressure fuel pump 2. A base end of the branch passage 8 is connected to the low pressure fuel passage 4 in the middle. The end of the branch passage 8 is connected to the fuel tank 3. A pressure regulator 9 is provided in the middle of the branch passage 8. The pressure regulator 9 opens when the pressure (fuel pressure) in the low-pressure fuel passage 4 exceeds a predetermined value, so that excess fuel in the low-pressure fuel passage 4 passes to the fuel tank 3 via the branch passage 8. Configured to return.

  A check valve 10 is disposed in the middle of the high-pressure fuel passage 5 described above. The check valve 10 is a one-way valve that allows a flow from the discharge port of the high-pressure fuel pump 2 to the delivery pipe 6 and restricts a flow from the delivery pipe 6 to the discharge port of the high-pressure fuel pump 2.

Connected to the delivery pipe 6 is a return passage 12 for returning surplus fuel in the delivery pipe 6 to the fuel tank 3. In the middle of the return passage 12, a relief valve 13 that switches between return and passage of the return passage 12 is disposed. The relief valve 13 is an electric or electromagnetically driven valve mechanism, and is opened when the fuel pressure in the delivery pipe 6 exceeds a target value.

  In the middle of the return passage 12, the end of the communication passage 14 is connected. A base end of the communication path 14 is connected to the high-pressure fuel pump 2. The communication passage 14 is a passage for guiding excess fuel discharged from the high-pressure fuel pump 2 to the return passage 12.

  Here, the fuel supply system in the present embodiment includes an ECU 15 for electrically controlling the above-described devices. The ECU 15 is an electronic control unit that includes a CPU, ROM, RAM, backup RAM, and the like. The ECU 15 is electrically connected to various sensors such as a fuel pressure sensor 16, an intake air temperature sensor 17, an accelerator position sensor 18, and a crank position sensor 19.

  The fuel pressure sensor 16 is a sensor that outputs an electrical signal correlated with the fuel pressure (discharge pressure of the high-pressure fuel pump) Ph in the delivery pipe 6. The intake air temperature sensor 17 outputs an electrical signal correlated with the temperature of air taken into the internal combustion engine. The accelerator position sensor 18 outputs an electrical signal correlated with the operation amount (accelerator opening) of the accelerator pedal. The crank position sensor 19 is a sensor that outputs an electrical signal correlated with the rotational position of the output shaft (crankshaft) of the internal combustion engine.

  The ECU 15 controls the low-pressure fuel pump 1 and the intake valve 2a based on the output signals of the various sensors described above. For example, the ECU 15 adjusts the opening / closing timing of the intake valve 2a so that the output signal (actual discharge pressure) Ph of the fuel pressure sensor 16 converges to the target discharge pressure Phtrg. At that time, the ECU 15 determines the drive duty (the solenoid energization time and the non-energization time) which is the control amount of the suction valve 2a based on the difference ΔPh (= Phtrg−Ph) between the actual discharge pressure Ph and the target discharge pressure Phtrg. Ratio) Dh is feedback-controlled. Specifically, the ECU 15 performs proportional-integral control (PI control) based on the difference ΔPh with respect to the drive duty Dh of the intake valve 2a. The target discharge pressure Phtrg is a value determined according to the target fuel injection amount of the fuel injection valve 7.

  In the proportional integral control described above, the ECU 15 determines the control amount determined according to the control amount (feed forward term) Tff determined according to the target fuel injection amount and the difference ΔPh between the actual discharge pressure Ph and the target discharge pressure Phtrg. The drive duty Dh is calculated by adding (proportional term) Tp and a control amount (integral term) Ti obtained by integrating a part of the difference ΔPh (for example, residual deviation of proportional control).

  It should be noted that the relationship between the target fuel injection amount and the feedforward term Tff and the relationship between the difference ΔPh and the proportional term Tp are determined in advance by adaptation work using experiments or the like. In the difference ΔPh, the proportion of the amount added to the integral term Ti is also determined in advance by an adaptation operation using an experiment or the like.

Further, the ECU 15 executes a process for reducing the discharge pressure (feed pressure) Pe of the low-pressure fuel pump 1 in order to reduce the power consumption of the low-pressure fuel pump 1 as much as possible. Specifically, the ECU 15 calculates the drive signal Dl of the low-pressure fuel pump 1 according to the following equation (1). The drive signal Dl here is a current value proportional to the discharge pressure Pe of the low-pressure fuel pump 1.
Dl = D1old + ΔTi * F−Cdwn (1)
D1old in equation (1) is the previous calculated value of the drive signal Dl. ΔTi in the equation (1) is the change amount ΔTi of the integral term Ti used for the proportional integral control (for example, the integral term Tiold used for the previous calculation of the drive duty Dh and the integral term used for the current calculation). Ti
(Ti-Tiold)). F in the equation (1) is a correction coefficient. As the correction coefficient F, an increase coefficient Fi of 1 or more is used when the change amount ΔTi of the integral term Ti is a positive value, and a decrease of less than 1 when the change amount ΔTi of the integral term Ti is a negative value. A factor Fd is used. Moreover, Cdwn in Formula (1) is a decreasing constant.

  When the drive signal Dl of the low-pressure fuel pump 1 is determined according to the above equation (1), the drive signal Dl of the low-pressure fuel pump 1 increases (discharges) when the integral term Ti shows an increasing tendency (ΔTi> 0). When the pressure Pe rises) and the integral term Ti shows a decreasing tendency or a constant value (ΔTi ≦ 0), the drive signal Dl of the low-pressure fuel pump 1 decreases (the discharge pressure Pe decreases).

  Here, the integral term Ti shows an increasing tendency when vapor is generated in the low-pressure fuel passage 4, in other words, when the fuel pressure in the low-pressure fuel passage 4 is lower than the saturated vapor pressure of the fuel. Here, the behavior of the integral term Ti and the fuel pressure in the high-pressure fuel passage 5 (actual discharge pressure of the high-pressure fuel pump 2) Ph when the discharge pressure (feed pressure) Pe of the low-pressure fuel pump 1 is continuously reduced is shown. As shown in FIG.

  In FIG. 2, when the feed pressure Pe falls below the saturated vapor pressure (t1 in FIG. 2), the integral term Ti shows a gentle increasing tendency. Thereafter, when the feed pressure Pe is further reduced, a suction failure or discharge failure of the high-pressure fuel pump 2 occurs (t2 in FIG. 2). When the suction failure or the discharge amount of the high-pressure fuel pump 2 occurs, the rate of increase of the integral term Ti increases and the fuel pressure Ph in the high-pressure fuel passage 5 decreases.

  Therefore, when the driving signal Dl of the low-pressure fuel pump 1 is determined by the above equation (1), the discharge pressure Pe of the low-pressure fuel pump 1 increases when the integral term Ti shows an increasing tendency (ΔTi> 0). When the integral term Ti shows a constant or decreasing tendency (ΔTi ≦ 0), the discharge pressure Pe of the low-pressure fuel pump 1 decreases, so that the suction failure and discharge failure of the high-pressure fuel pump 2 due to the occurrence of vapor are suppressed. However, the discharge pressure Pe of the low-pressure fuel pump can be reduced.

  Here, the low-pressure fuel pump 1 of the present embodiment includes a drive circuit 100 for driving the low-pressure fuel pump 1 in accordance with a drive signal Dl (current value) output from the ECU 14. As shown in FIG. 3, the drive circuit 100 includes two operational amplifiers 101 and 102, a transistor 103, and two resistors 104 and 105.

  The operational amplifier 101 amplifies and outputs the difference between the drive signal Dl (current value) output from the ECU 15 and the current value flowing through the low-pressure fuel pump 1. The operational amplifier 102 amplifies and outputs the difference between the drive signal Dl output from the ECU 15 and the difference output from the operational amplifier 101. The transistor 103 switches between application and non-application of the battery voltage B to the low-pressure fuel pump 1 in accordance with the output of the operational amplifier 102. The resistor 104 is a resistor for applying the battery voltage B to the low-pressure fuel pump 1. The resistor 105 is a resistor for detecting the value of the current flowing through the low-pressure fuel pump 1, and corresponds to the detecting means according to the present invention.

  According to the drive circuit 100 configured as described above, the battery voltage B applied to the low-pressure fuel pump 1 is such that the current value (consumption current value) that actually flows through the low-pressure fuel pump 1 matches the drive signal Dl. The duty is controlled. The drive circuit 100 corresponds to drive means according to the present invention.

Here, when the flow rate of the fuel changes when the applied voltage of the low-pressure fuel pump 1 is constant, the pressure (discharge pressure) of the fuel discharged from the low-pressure fuel pump 1 changes as shown in FIG.
On the other hand, when the current flowing through the low-pressure fuel pump 1 (consumption current) is constant, as shown in FIG. 5, the discharge pressure of the low-pressure fuel pump 1 hardly changes even if the fuel flow rate changes. This is because the current consumption value of the low-pressure fuel pump 1 is proportional to the torque of the low-pressure fuel pump 1, in other words, the discharge pressure of the low-pressure fuel pump 1.

  Therefore, when the applied voltage of the low-pressure fuel pump 1 is controlled by the drive circuit 100 as shown in FIG. 3, the discharge pressure of the low-pressure fuel pump 1 can be converged to a desired discharge pressure regardless of the fuel flow rate. It becomes possible.

  Incidentally, clogging may occur in the low-pressure fuel passage 4. In particular, when a filter is disposed in the low-pressure fuel passage 4, the filter may be clogged. In such a case, the fuel pressure in the low-pressure fuel passage 4 immediately upstream of the high-pressure fuel pump 2 may be lower than the pressure commensurate with the consumption current value of the low-pressure fuel pump 1. As a result, there is a possibility that fuel vapor may be generated or a suction failure of the high-pressure fuel pump 2 may occur.

  Further, when fuel having a property that is assumed in advance (reference fuel) is separated from the fuel tank 3, the fuel pressure in the low-pressure fuel passage 4 and the low-pressure fuel pump immediately upstream of the high-pressure fuel pump 2 are supplied. There is a possibility that the discharge pressure corresponding to the current consumption value of 1 will deviate.

  For example, when the fuel (used fuel) supplied into the fuel tank 3 has lighter properties than the reference fuel, the fuel pressure immediately upstream of the high-pressure fuel pump 2 is lower than when the reference fuel is used. . In that case, the fuel pressure immediately upstream of the high-pressure fuel pump 2 is lower than the discharge pressure corresponding to the current consumption value of the low-pressure fuel pump 1. As a result, there is a possibility that fuel vapor may be generated or a suction failure of the high-pressure fuel pump 2 may occur.

  On the other hand, when the fuel (used fuel) supplied into the fuel tank 3 has heavier properties than the reference fuel, the fuel pressure immediately upstream of the high-pressure fuel pump 2 is higher than when the reference fuel is used. Become. In that case, the fuel pressure immediately upstream of the high-pressure fuel pump 2 becomes higher than the discharge pressure corresponding to the current consumption value of the low-pressure fuel pump 1. As a result, the power consumption of the low-pressure fuel pump 1 may increase unnecessarily.

  Therefore, the fuel injection control system of the internal combustion engine of the present embodiment uses the current value (consumption current value of the low-pressure fuel pump 1) detected by the resistor 105 of the drive circuit 100 to correct the abnormality of the fuel injection control system. It was made to detect. The abnormality mentioned here includes an abnormality caused by the fuel property in addition to an abnormality caused by clogging of the low-pressure fuel passage 4 or deterioration of the low-pressure fuel pump.

  Hereinafter, the abnormality detection method in the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing a processing routine executed by the ECU 15 when detecting an abnormality in the fuel injection control system. This processing routine is stored in advance in the ROM or the like of the ECU 15, and is periodically executed by the ECU 15.

  In the processing routine of FIG. 6, the ECU 15 first reads the current consumption value of the low-pressure fuel pump in S101. Specifically, the ECU 15 reads a current value (current consumption value) I flowing through the resistor 105 of the drive circuit 100.

In S102, the ECU 15 converts the consumption current value I read in S101 into the discharge pressure Pe of the low-pressure fuel pump 1. At this time, the relationship between the current consumption value I and the discharge pressure Pe is obtained in advance by an adaptation process using an experiment or the like, and is stored in the ROM of the ECU 15 as a map or a function expression. The ECU 15 executes the processing of S102, thereby realizing the calculation means according to the present invention.

  In S103, the ECU 15 acquires the fuel pressure Pf in the low pressure fuel passage 4 immediately upstream of the high pressure fuel pump 2. At that time, a pressure sensor may be arranged in the low-pressure fuel passage 4 immediately upstream of the high-pressure fuel pump 2, and the ECU 15 may read the measured value of the pressure sensor. Further, the ECU 15 may calculate the fuel pressure Pf using the fuel temperature in the low pressure fuel passage 4 immediately upstream of the high pressure fuel pump 2 as a parameter. The relationship between the fuel temperature and the fuel pressure Pf in the low-pressure fuel passage 4 immediately upstream of the high-pressure fuel pump 2 is obtained in advance by an adaptation process using experiments or the like, and is stored in the ROM of the ECU 15 as a map or a function expression. Shall. Further, the fuel temperature in the low pressure fuel passage 4 immediately upstream of the high pressure fuel pump 2 may be directly measured by a temperature sensor, or the measured value of the intake air temperature sensor 17 may be substituted. In addition, the acquisition means concerning this invention is implement | achieved when ECU15 performs the process of S103.

  In S104, the ECU 15 calculates a difference ΔP between the discharge pressure Pe calculated in S102 and the fuel pressure Pf calculated in S103. Subsequently, the ECU 15 proceeds to S105, and determines whether or not the absolute value of the difference ΔP calculated in S104 is larger than a threshold value Pthre. The threshold value Pthre here is the minimum difference ΔP1 at which clogging of the low-pressure fuel passage 4 can affect the operating state of the internal combustion engine, and the minimum difference ΔP2 at which the current consumption value of the low-pressure fuel pump 1 is considered to exceed the allowable range. And the difference between the property of the fuel used and the property of the reference fuel is set to a value obtained by adding a margin to the smallest value among the minimum difference ΔP3 that is considered to deteriorate the combustion stability and exhaust emission of the internal combustion engine. Is done.

  If an affirmative determination is made in S105, the ECU 15 proceeds to S106 and determines that an abnormality has occurred. In that case, the ECU 15 may prompt the driver to repair the vehicle by turning on a warning light or the like provided in the vehicle interior. On the other hand, if a negative determination is made in S105, the ECU 15 proceeds to S107 and determines that no abnormality has occurred (normal).

  According to the processing routine described above, it is possible to detect an abnormality caused by clogging of the low-pressure fuel passage 4 or a change in fuel properties.

  In this embodiment, an abnormality caused by clogging of the low-pressure fuel passage 4 is not distinguished from an abnormality caused by fuel properties. However, when a filter is disposed in the low-pressure fuel passage 4, the difference ΔP is a threshold value. If Pthre is exceeded, it may be determined that the filter is clogged. On the other hand, when the filter is not disposed in the low-pressure fuel passage 4, if the difference ΔP exceeds the threshold value Pthr, it is determined that the property of the fuel used is lighter or heavier than the reference fuel, and the fuel injection amount is You may make it correct | amend.

DESCRIPTION OF SYMBOLS 1 Low pressure fuel pump 2 High pressure fuel pump 2a Suction valve 3 Fuel tank 4 Low pressure fuel passage 5 High pressure fuel passage 6 Delivery pipe 7 Fuel injection valve 8 Branch passage 9 Pressure regulator 10 Check valve 11 Pulsation damper 12 Return passage 13 Relief valve 14 Passage 15 ECU
16 Fuel Pressure Sensor 100 Drive Circuit 101 Op Amp 102 Op Amp 103 Transistor 104 Resistor 105 Resistor

Claims (4)

An electric fuel pump disposed in a fuel path from the fuel tank to the fuel injection valve ;
A booster pump that is disposed in a fuel path downstream from the electric fuel pump and pressurizes the fuel discharged from the electric fuel pump;
A pressure sensor for detecting a discharge pressure of the booster pump;
A calculation unit for calculating a drive signal of the boost pump using a proportional term and an integral term calculated using a deviation between a target discharge pressure of the boost pump and a detection value of the pressure sensor as a parameter;
Reduction processing means for reducing the target discharge pressure of the electric fuel pump in accordance with the change tendency of the integral term;
Detecting means for detecting current consumption of the electric fuel pump;
Calculation means for calculating the pressure of fuel discharged from the electric fuel pump, using the current consumption detected by the detection means as a parameter;
Obtaining means for obtaining fuel pressure in a fuel path downstream from the electric fuel pump;
A determination unit that determines that an abnormality has occurred in the system when the difference between the fuel pressure calculated by the calculation unit and the fuel pressure acquired by the acquisition unit exceeds a threshold;
A fuel injection control system for an internal combustion engine.   2. The fuel injection control system for an internal combustion engine according to claim 1, further comprising drive means for driving the electric fuel pump so that a current consumption of the electric fuel pump matches a target value.   3. The fuel injection control system for an internal combustion engine according to claim 1, wherein the acquisition means calculates a fuel pressure using a fuel temperature as a parameter. An electric fuel pump disposed in a fuel path from the fuel tank to the fuel injection valve ;
A booster pump that is disposed in a fuel path downstream from the electric fuel pump and pressurizes the fuel discharged from the electric fuel pump;
A pressure sensor for detecting a discharge pressure of the booster pump;
A calculation unit for calculating a drive signal of the boost pump using a proportional term and an integral term calculated using a deviation between a target discharge pressure of the boost pump and a detection value of the pressure sensor as a parameter;
Reduction processing means for reducing the target discharge pressure of the electric fuel pump in accordance with the change tendency of the integral term;
Detecting means for detecting current consumption of the fuel pump;
Obtaining means for obtaining fuel pressure in a fuel path downstream from the fuel pump;
Calculation means for calculating the consumption current of the fuel pump, using the fuel pressure acquired by the acquisition means as a parameter;
Determination means for determining that an abnormality has occurred in the system when the difference between the consumption current detected by the detection means and the consumption current calculated by the calculation means exceeds a threshold;
A fuel injection control system for an internal combustion engine.

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