DE102004029454A1 - Abnormality diagnostic unit of fuel supply system - Google Patents

Abstract

A low-pressure side fuel pressure sensor (33) senses a fuel pressure (a low-pressure side fuel pressure) within a low-pressure side fuel pipe (13) connecting a low-pressure pump (12) to a high-pressure pump (14). An electronic control unit (ECU) (36) counts the number of determinations that the low-pressure side fuel pressure is lower than a normal range in a first predetermined period, and determines that a first abnormal operation is established if the counted value is equal to or becomes larger than a predetermined value. The ECU (36) counts the number of determinations that the low-pressure side fuel pressure is higher than the normal range in a second predetermined time period, and determines that a second abnormal operation is introduced if the counted value is equal to or greater than that predetermined value.

Description

The The present invention relates to a diagnostic unit of a High pressure fuel supply system of an internal combustion engine to the Presence of an abnormality in the high pressure fuel delivery system. The high pressure fuel delivery system sets fuel drawn from a fuel tank by a low-pressure pump is under a high pressure and leads the fuel under pressure to fuel injectors too.

In a direct-injection engine, the fuel directly injected into the cylinder, the injected fuel must pass through increasing one Injection pressure can be atomised to a high pressure to increase flammability sure. That is why the machine of the direct injection type sets the Fuel passing through a low pressure pump from a fuel tank being pulled under a high pressure, being a high pressure pump is used, which is driven by a camshaft of the machine is, and leads pressurize the fuel to fuel injectors. In In the above high-pressure fuel supply system, the pressure of the under pressure from the high-pressure pump to the fuel injection valves supplied fuel (hereinafter high pressure side fuel pressure) with a fuel pressure sensor felt and a fuel discharge amount of the high-pressure pump from a deviation between the sensed fuel pressure and a Target fuel pressure regulated. In this way, the high-pressure side Fuel pressure controlled to the target pressure. At this time will be the fuel discharge amount of the high-pressure pump by controlling a Valve closing period (an actual Stroke of a piston) of a flow control valve Regulates that the fuel delivery rate by stroke of the piston High pressure pump controls.

Some The above high-pressure fuel supply systems have an abnormality diagnosis function. For example, in one in the unaudited publication of the Japanese Patent Application Number 2000-274322 disclosed high pressure fuel delivery system determines that the low pressure pump is abnormal if the high pressure side Fuel pressure sensed by the fuel pressure sensor is equal to or lower than a predetermined pressure when the Engine is started, and, if the high-pressure side fuel pressure remains equal to or lower than the predetermined pressure, if after the engine starts a predetermined period of time elapses, or just before a function to increase the pressure of the high pressure pump is performed sufficiently.

The Abnormalitätsdiagnoseverfahren determines the presence of the abnormality in the low-pressure pump during the Period from the start of the engine to the pressure increase function the high-pressure pump is sufficiently carried out. That is why the abnormality in an early phase are not detected and the detection of the abnormality becomes disadvantageous until the next one Start of the machine postponed, even if the low-pressure pump while operation of the machine becomes abnormal after this period. Furthermore can the abnormality at all not be detected, even if any other sections than the Low pressure pump will be abnormal.

It It is therefore an object of the present invention to provide an abnormality diagnosis unit to provide a high-pressure fuel supply system of an internal combustion engine, that is capable of an abnormality in the high-pressure fuel supply system in his early days State and specify the location of the abnormality.

According to one The aspect of the present invention has a high pressure fuel delivery system an internal combustion engine, a fuel sensing device for sensing a Fuel pressure (hereinafter low-pressure side fuel pressure) in a fuel passage, which is a low-pressure pump with a High pressure pump connects. If by the fuel pressure sensing device Feels low-pressure side fuel pressure is lower than a normal range, it is determined that a first abnormal operation has been introduced. If the low pressure side fuel pressure is higher than the normal range, determines that a second abnormal operation has been introduced. Since the high-pressure fuel supply system, the fuel pressure sensing device to feel the Low-pressure side fuel pressure can, starting from the perceived Value of the fuel pressure sensing device determine whether the low-pressure side fuel pressure within the normal range, not only when the machine is started, but also while the machine is operated. If an abnormality in a section for regulating the low-pressure side fuel pressure is generated, the abnormality can in her early days Condition to be recorded. Furthermore becomes the abnormality captured while between the first abnormal operation, in which the low-pressure side Fuel pressure is lower than the normal range, and the second abnormal operation in which the low-pressure side fuel pressure is higher than the normal range, is distinguished. That's why the place can the abnormality be specified.

characteristics and advantages of an embodiment as well as operating procedures and the function of the parts, become from a study of the following detailed description, the appended claims and the drawings, all of which form part of this application form. In the figures:

1 FIG. 12 is a schematic diagram showing a high-pressure fuel supply system according to an embodiment of the present invention; FIG.

2 FIG. 12 is a schematic diagram showing a structure of a high-pressure pump according to the embodiment; FIG.

3 FIG. 11 is a time chart showing the behavior of a flow control valve and the high-pressure pump according to the embodiment; FIG.

4 FIG. 10 is a first flowchart showing the processing of an abnormality diagnosis routine according to the embodiment; FIG.

5 FIG. 14 is a second flowchart showing the processing of the abnormality diagnosis routine according to the embodiment; FIG.

6 FIG. 12 is a flowchart showing the processing of an abnormality continuation-period targeting routine of the embodiment; FIG.

7 FIG. 11 is a time chart showing the behavior of a low-pressure side fuel pressure in a first abnormal operation and a second abnormal operation according to the embodiment; FIG. and

8th FIG. 13 is a timing chart showing an example of abnormality diagnosis according to the embodiment. FIG.

Regarding 1 1, a high pressure fuel supply system of a direct injection type engine (internal combustion engine) according to an embodiment of the present invention is illustrated. How out 1 As can be seen, a low pressure pump 12 is for drawing fuel in a fuel tank 11 provided, which stores the fuel. The low pressure pump 12 is powered by an electric motor that uses a battery as a power source. The from the low pressure pump 12 discharged fuel is through a low-pressure side fuel pipe (a fuel passage) 13 to a high pressure pump 14 fed. A pressure regulator 15 is in the low pressure side fuel pipe 13 intended. The pressure regulator 15 regulates a discharge pressure of the low-pressure pump 12 (a pressure for supplying the fuel to the high-pressure pump 14 ) to a predetermined pressure (for example, about 400 kPa). Excess fuel, which may reach a pressure higher than the predetermined pressure, is passed through a fuel return pipe 16 in the fuel tank 11 recycled. How out 2 it can be seen, is the high-pressure pump 14 a piston pump, by reciprocating a piston 19 in a cylindrical pump chamber 18 Fuel pulls or releases. The piston 19 is by a rotary motion of a cam 21 powered by a camshaft 20 the machine is adapted. In this way, a stroke rate of the piston 19 changed in cycle according to a crank angle as indicated by a solid line "HUB" in FIG 3 is shown.

How out 2 can be seen is a flow control valve (FCV) 22 on one side of an inlet 23 the pump chamber 18 intended. The flow control valve 22 is an electromagnetic valve of a normally open type. The flow control valve 22 has a valve member 26 for opening or closing the inlet 23 , a feather 27 for biasing the valve member 26 in a valve opening direction and a solenoid 28 , for driving the valve part 26 in a valve closing direction using electromagnetic force. If the drive current is not on the solenoid 28 is applied, the valve part 26 by the biasing force of the spring 27 opened, and the inlet 23 it is open. If the drive current to the solenoid 28 is applied, the valve part 26 by the electromagnetic driving force of the solenoid 28 against the biasing force of the spring 27 closed, and the inlet 23 is blocked.

In a drawing tank of the high-pressure pump 14 (a tact in which the piston 19 moving from a top dead center to a bottom dead center) becomes the flow control valve 22 opened and the fuel is in the pump chamber 18 drawn. In 3 a solid line "a" indicates a state of the flow control valve (FCV) 22 , A section "TRAIN" in 3 sets the stroke rate of the high pressure pump 14 In a discharge cycle (a cycle in which the piston 19 moves from the bottom dead center to the top dead center) becomes the start time of the valve closing operation of the flow control valve 22 controlled. In this way, the fuel discharge amount is regulated and the fuel discharge pressure of the high pressure pump 14 (hereinafter, a high-pressure side fuel pressure) is controlled. A section "DISCHARGE" in 3 represents the discharge cycle of the high-pressure pump 14 represents.

For example, when the high-pressure side fuel pressure is to be increased, the start time of the closing operation of the flow control valve becomes 22 from the solid line "a" in 3 ready time set to one by a dashed line "b" in 3 preferred. In this way, the valve closing period (an effective stroke "ST-E") is extended to the end of the discharge stroke, and the fuel discharge amount of one through a region "A" in FIG 3 In contrast, the start time of the closing operation of the flow control valve is increased to an amount shown by another range "B" 22 from the dashed line "b" in 3 provided time to that by the solid line "a" in 3 delayed time. In this way, the valve closing period (the effective stroke ST-E) is contracted to the end of the discharge cycle and the fuel discharge amount is reduced. At this time, the fuel flows back to a low-pressure side, and a large fluctuation is generated by a pump function while the flow control valve 22 is open during the discharge cycle. Therefore, the fluctuation will be explained later by a fluctuation damper 34 added.

A check valve 25 for preventing the return of the discharged fuel is on one side of an outlet 24 the high pressure pump 14 intended. How out 1 it can be seen, that of the high pressure pump 14 discharged fuel through a high-pressure side fuel pipe 29 to a delivery tube 30 fed under pressure. The high pressure fuel is from the feed tube 30 to the fuel injection valves 31 the corresponding cylinder distributed. A high pressure side fuel pressure sensor 32 for sensing the high-pressure side fuel pressure is in the supply pipe 30 intended.

A low-pressure side fuel pressure sensor 33 (Fuel pressure sensing device) for sensing the fuel pressure on the intake 23 Side of the high pressure pump 14 (hereinafter, a low-pressure side fuel pressure) is in a low-pressure side fuel pipe 13 provided that the low-pressure pump 12 with the high pressure pump 14 combines. The fluctuation damper 34 (A device for reducing a fuel pressure fluctuation) for reducing the fluctuation of the low-pressure side fuel pressure is with a connection between the inlet 23 the high pressure pump 14 and the low pressure side fuel pipe 13 connected. The fluctuation damper 34 has a diaphragm that absorbs the fluctuation of the low-pressure side fuel pressure and the fuel pressure in the low-pressure side fuel pipe 13 stabilized.

Output signals (sensed fuel pressures) of the high-pressure side fuel pressure sensor 32 and the low-pressure side fuel pressure sensor 33 be in an electronic control unit (an ECU) 36 entered. The ECU 36 is designed aligned in the center of a microcomputer. The ECU 36 has a ROM (memory device) and performs a fuel pressure control routine stored in the ROM. In this way, the ECU regulates 36 the valve closing start time (the actual stroke) of the flow control valve 22 the high pressure pump 14 so that the high pressure side fuel pressure passing through the high pressure side fuel sensor 32 is felt, matches the target fuel pressure.

The ECU 36 executes an abnormality diagnosis routine stored in the ROM (see 4 and 5 ) to perform the abnormality diagnosis of the high-pressure fuel supply system. At abnormality diagnosis existence of an abnormality in parts (the low-pressure pump 12 , the vibration damper 34 and the pressure regulator 15 ) that regulate the low-pressure side fuel pressure in the high-pressure fuel supply system. If, for example, the output of the low-pressure pump 12 Abnormally decreases and the amount of the low pressure pump 12 discharged fuel of the low-pressure side fuel pipe 13 output fuel decreases abnormally, the fuel pressure (the low-pressure side fuel pressure) HP in the low-pressure side fuel pipe decreases 13 under a normal range RN as indicated by a solid line "a" in FIG 7 is apparent. If that of the fluctuation damper 34 outflowing fuel increases abnormally (in the case where a large hole is formed in the diaphragm), or if the amount of fuel passing through the pressure regulator 15 recirculated fuel increases abnormally, the low-pressure side fuel pressure HP also decreases below the normal range RN. If the reduction effect of the fuel pressure fluctuation of the fluctuation damper 34 is abnormally reduced (in the case where a small hole is formed in the diaphragm), the low-pressure side fuel pressure HP exceeds the normal range RN as indicated by a solid line "b" in FIG 7 is shown. The low-pressure side fuel pressure HP also exceeds the normal range RN if the fuel return function of the pressure regulator 15 fails, and the return operation of the fuel in the fuel tank 11 is stopped.

How out 7 is apparent, the low-pressure side fuel pressure HP increases at a discharge stroke of the high-pressure pump 14 and decreases in the pull stroke of the high pressure pump 14 , Therefore, in an early state of the generation of the abnormality, the low-pressure side fuel pressure HP periodically deviates from the normal range RN. That is why at the in 4 and 5 The abnormality diagnosis routine shown in FIG. 16 counts how often it is determined that the low-pressure side fuel pressure HP is lower than the normal range RN during a first predetermined period. If the counted value becomes equal to or greater than a first predetermined number, it is determined that a first abnormal operation is introduced. The first abnormal operation in which the low-pressure-side fuel pressure HP abnormally decreases is achieved by reducing the output power of the low-pressure pump 12 (The abnormal decrease of the fuel discharge amount of the low-pressure pump 12 ), the abnormality in the fluctuation absorber 34 (Outflow of the fuel to a large extent) or the abnormality in the pressure regulator 15 (abnormally increasing the amount of the recirculated fuel) caused. Therefore, it can be determined that the reduction of the output of the low-pressure pump 12 , the abnormality in the fluctuation absorber 34 or the abnormality in the pressure regulator 15 is caused, if it is determined that the first abnormal operation is introduced.

In addition, in the in 4 and 5 The number of times the low-pressure-side fuel pressure HP is determined to be higher than the normal range RN in a second predetermined time period is counted as shown in the abnormality diagnosis routine. If the counted value becomes equal to or greater than a second predetermined number, it is determined that a second abnormal operation has been introduced. The second abnormal operation in which the low-pressure-side fuel pressure HP abnormally increases is determined by the abnormality in the fluctuation damper 34 (the abnormal decrease in the effect of the fuel pressure fluctuation reduction) or the abnormality in the pressure regulator 15 (causing the defect in the fuel return function). Therefore, it can be determined that the abnormality in the fluctuation damper 34 or the abnormality in the pressure regulator 15 is caused, if it is determined that the second abnormal operation is introduced.

Next, the contents of the processing of the abnormality routine from 4 and 5 explained. In the 4 and 5 The abnormality diagnosis routine shown in FIG. 1 is every 180 ° every crank angle (for example, at each end time of the exhaust stroke and at each end time of the high pressure pump pull clock 14 ) to detect the substantially maximum value and substantially minimum value of the low-pressure side fuel pressure HP. If the routine is started, first, in step S101, the low-pressure-side fuel pressure HP inputted through the low-pressure-side fuel pressure sensor is input 33 is felt. Then, in step S102, it is determined whether the low-pressure side fuel pressure HP is within the normal range RN. The normal range RN of the low-pressure side fuel pressure HP extends between a pressure lower by an allowable fuel pressure variation α (kPa) than the target pressure (for example, 400 kPa) of the pressure regulator 15 and another pressure higher than the target pressure by an allowable fuel pressure variation α.

If it is determined in step S102 that the low-pressure side fuel pressure HP is within the normal range (FIG. 400 - α <HP <400 + α), the processing proceeds to step S103. In step S103, a normality counter CNORM is incremented to count how many times it is determined that the low-pressure side fuel pressure HP is within the normal range. Then, in step S104, it is determined whether or not the value of the normality counter CNORM is equal to or greater than a predetermined number N. If the value of the normality counter CNORM is less than the predetermined number N, the routine is terminated immediately.

If in turn, the value of the normality counter CNORM is equal to or greater as the predetermined number N, it is determined that the low-pressure side Fuel pressure HP is normal and the normality counter (a normality determination number) is CFAIL to count, how often the low-pressure side fuel pressure HP is abnormal or outside the normal range RN is reset to 0. Then in step S106, an abnormality continuation period counter TFAIL to count one Period of continuation of the abnormal state is reset to 0. Then, in step S107, an abnormality determination flag XFAIL is set to 0 reset.

If it is determined that the low-pressure side fuel pressure HP is up outside of the normal range RN (HP ≤ 400 - α or HP ≥ 400 + α), the flag XFAIL becomes for determination the abnormality set to 1 in step S108. Then, in step S109, the abnormality counter CFAIL elevated. Then, in step S110, the normality counter CNORM is reset to 0. Then, in step S111, it is determined whether the value of the abnormality counter CFAIL is equal to or greater as a predetermined number N2. If it is determined that the value of Abnormality counter CFRIL is less than the predetermined number N2, the routine is terminated without the determination of abnormality to fix.

In turn, if it is determined that the value of the abnormality counter CFAIL is equal to or greater than the predetermined number N2, it is determined in step S112 whether the low-pressure side fuel pressure HP is lower than the normal range RN (HP <400-α). If it is determined that the low-pressure side fuel pressure HP is less than the normal range (HP <400 - α), it is determined in step S113 whether the abnormality continuation period counter TFAIL is shorter than a first predetermined period β. If it is determined that the abnormality continuation period counter TFAIL is short zer is the first predetermined period β, a first abnormality flag X1 is set to 1 in step S114. In the case where the first abnormality flag X1 is set to 1, it is determined that the first abnormal operation in which the low-pressure side fuel pressure HP abnormally drops is established. In the meantime, it is determined that the abnormality is in the reduction of the output of the low-pressure pump 12 (the abnormal decrease in the fuel delivery amount of the low-pressure pump 12 ), the abnormality in the fluctuation absorber 34 (The outflow of fuel in a large amount) or the abnormality in the pressure regulator 15 (the abnormal increase in the amount of the returned fuel) is caused.

Then, in step S119, a warning lamp on a dashboard is turned on or it starts to blink, or an alarm display is displayed on a display of the instrument panel to inform a driver of the vehicle of the abnormality. Subsequently, in step S120, a fail-safe operation is performed. In the failover process, at least the exposure of the low pressure pump 12 , the suspension of fuel injection by the fuel injectors 31 and continuing to open the flow control valve 22 carried out. The flow control valve 22 controls the fuel delivery amount of the high pressure pump 14 per stroke of the piston 19 , Any of the above methods stops fuel delivery to the engine. Therefore, the operation of the machine can be automatically stopped when the abnormality is caused. In the fail-safe operation, at least one of the above methods may be performed after a control is performed for a certain period of time, which makes it possible to drive the vehicle to a safe place.

If the result of the determination in step S113 is "NO", or if the abnormality continuation period counter TFAIL same or longer is than the predetermined period β, it is determined that the low-pressure side Fuel pressure HP is normal, and the abnormality counter TFAIL is reset to 0 in step S115.

In the case where the result of the determination in step S112 is "NO" or in the case where the low-pressure side fuel pressure HP is higher than the normal range RN, it is determined in step S116 whether the abnormality continuation period counter TFAIL is shorter than If it is determined that the abnormality continuation period counter TFAIL is shorter than the second predetermined time period γ, a second abnormality flag X2 is set to 1 in step S117. In this way, it is determined that the second abnormal operation in which the low-pressure-side fuel pressure HP abnormally rises is introduced, and it is determined that the abnormality in the fluctuation damper 34 (the abnormal reduction in the effect of reducing the fuel pressure fluctuation), or the abnormality in the pressure regulator 15 (the defect of the fuel return function) is caused. The second predetermined period γ may be the same as the first predetermined period β, or may be different from the first predetermined period β.

Then at step S121, the warning lamp on the dashboard is turned on, or it starts flashing, or the warning display is on the display of the dashboard displayed to the driver of the vehicle of the abnormality to inform. Subsequently, in step S122, the fail-safe operation as performed in step S120.

at in the case where the result of the determination in step S116 is "NO", or in the case where at the abnormality continuation period counter TFAIL same or longer is the second predetermined period γ, it is determined that the low-pressure side Fuel pressure HP is normal and the abnormality counter CFAIL is in step S118 reset to 0.

One out 6 The abnormality continuation period counter routine routine is started every predetermined period (for example, 4 ms) and counts the period of continuation of the abnormal condition as follows. If the routine is started, it is first determined in step S201 whether the abnormality determination flag XFAIL is 1 (or whether the low-pressure side fuel pressure HP is out of the normal range RN). If the abnormality determination flag XFAIL is 1, the abnormal state continuation period is counted by increasing the abnormality continuation period counter TFAIL in step S202. If it is determined in step S201 that the abnormality determination flag XFAIL is 0 (or the low-pressure side fuel pressure HP is within the normal range RN), the routine is terminated immediately.

Next, an example of the abnormality diagnosis of the present embodiment will be based on one of 8th Explained time chart explained. This in 8th The timing chart shown is an example of the control in the case where the second abnormal operation (for example, the abnormality in the fluctuation damper 34 ) is caused, in which the low-pressure side fuel pressure HP rises abnormally. If the low-pressure-side fuel pressure HP abnormally rises above the normal range RN, the abnormality counter CFAIL is incremented each time the abnormality is taken.

If once the flag XFAIL for determining the abnormality is set to 1 once, when the low-pressure side fuel pressure HP is the normal range RN exceeds, the flag XFAIL for determining the abnormality at 1 maintained until at least a predetermined number of N times consecutively a condition is detected in which the low-pressure side fuel pressure HP is within normal range RN. While that Flag XFAIL is set to 1 to determine the abnormality Continuation period of the abnormal state by increasing the Abnormality continuation period counter TFAIL counted at a predetermined cycle.

Then, if the value of the abnormality counter CFAIL at a time tF in 8th reaches the predetermined number N2 before the abnormality continuation period counter TFAIL reaches the second predetermined time period γ, the second flag of the abnormal operation X2 is set to 1 at this time. In this way, it is determined at the time tF that the second abnormal operation in which the low-pressure side fuel pressure HP abnormally rises is established, and it is determined that the abnormality in the fluctuation damper 34 (the abnormal reduction in the effect of reducing the fuel pressure fluctuation) or the abnormality in the pressure regulator 15 (the defect in the fuel return function) is caused.

If the second flag of the abnormal operation X2 is set to 1, the fail-safe operation is performed to the low-pressure pump 12 to stop (like out 8th it can be seen) to the fuel injection by the fuel injection valves 31 stop, or the flow control valve 22 the high pressure pump 14 to open continuously. In this way, the operation of the machine is automatically stopped when the abnormality is caused. In the meantime, the warning lamp on the dashboard is turned on or it starts flashing or the alarm display is displayed on the dashboard display to inform the driver of the abnormality.

In the present embodiment, the low-pressure side fuel pressure sensor is 33 set to the fuel pressure (low-pressure side fuel pressure HP) in the low-pressure side fuel pipe 13 to feel that the low pressure pump 12 with the high pressure pump 14 combines. If the low-pressure side fuel pressure HP, by the low-pressure side fuel pressure sensor 33 is less than the normal range RN, it is determined that the first abnormal operation is introduced. If the low-pressure side fuel pressure HP is higher than the normal range RN, it is determined that the second abnormal operation is established. Therefore, the first abnormal operation in which the low-pressure-side fuel pressure HP abnormally decreases and the second abnormal operation in which the low-pressure-side fuel pressure HP abnormally increases can be based on the sensed value of the low-pressure side fuel pressure sensor 33 not only selected when the machine is started, but also when the machine is operated. In addition, the location of the abnormality can be specified.

It is determined that the first abnormal operation is established if the number of determinations that the low-pressure side fuel pressure HP is lower than the normal range RN becomes equal to or greater than the predetermined number N2 within the first predetermined period β. Therefore, it is not determined that the first abnormal operation is established, even if an immediate drop in the low-pressure side fuel pressure HP of the high-pressure pump 14 causing a small effect on the fuel discharge amount (or the high-pressure side fuel pressure). As a result, the reliability of the abnormality detection can be improved.

Similarly, it is determined that the second abnormal operation is established if the number of determinations that the low-pressure side fuel pressure HP is higher than the normal range RN within the second predetermined period γ becomes equal to or greater than the predetermined number N2. Therefore, it is determined that the second abnormal operation is introduced even if an immediate rise in the low-pressure side fuel pressure HP is caused, which has little effect on the fuel discharge amount (or the high-pressure side fuel pressure) of the high-pressure pump 14 Has. In the present embodiment, the identical predetermined number N2 is used in the determination of the first abnormal operation and the second abnormal operation. Alternatively, the first abnormal operation and the second abnormal operation may be determined based on different determination numbers.

In the present embodiment, the pressure regulator is 15 on the side of the outlet of the low-pressure pump 12 provided to the discharge pressure of the low-pressure pump 12 to control the target pressure (for example 400 kPa) (or the fuel supply pressure to the high pressure pump 14 ). Alternatively, the pressure regulator 15 be omitted and the speed (Abgabefließrate) of the drive motor of the low-pressure pump 12 can be controlled so that the low-pressure side fuel pressure HP, by the low-pressure side fuel pressure sensor 33 is felt, coincides with the target fuel pressure (for example, 400 kPa).

The The present invention should not be limited to the disclosed embodiments limited but can be introduced in many other ways, without departing from the scope of the invention as defined in the appended claims is.

A low-pressure side fuel pressure sensor 33 senses a fuel pressure (a low pressure side fuel pressure) within a low pressure side fuel pipe 13 that is a low pressure pump 12 with a high pressure pump 14 combines. An electronic control unit (ECU) 36 counts the number of times that it is determined that the low-pressure side fuel pressure is lower than a normal range in a first predetermined period, and determines that a first abnormal operation is established if the counted value is equal to or greater than a predetermined value , The ECU 36 The number of times the low-pressure side fuel pressure is determined to be higher than the normal range in a second predetermined time period counts, and determines that a second abnormal operation is established if the counted value is equal to or greater than the predetermined value.

Claims (7)

Device for diagnosing an abnormality of a high-pressure fuel supply system of an internal combustion engine with a low-pressure pump ( 12 ) for drawing fuel from a fuel tank ( 11 ) and a high-pressure pump ( 14 ) to pressurize the from the low pressure pump ( 12 ) delivered fuel to a high pressure, and for supplying the fuel under high pressure to fuel injection valves ( 31 ), characterized by: a pressure sensing device ( 33 ) for sensing a low-pressure side fuel pressure of the fuel within a fuel passage ( 13 ), the low pressure pump ( 12 ) with the high-pressure pump ( 14 ) connects; a first determination means (S102, S108-S115) for determining that a first abnormal operation is introduced if the low-pressure side fuel pressure supplied by the pressure sensing means (S102) 33 ) is less than a normal range; second determination means (S102, S108-S112, S116-S118) for determining that a second abnormal operation is introduced if the low-pressure side fuel pressure detected by the pressure sensing means (S102) 33 ) is higher than the normal range. Apparatus for diagnosing abnormality of the high-pressure fuel supply system The internal combustion engine according to claim 1, further characterized that the first determining means (S102, S108-S115) determines that the first abnormal operation is introduced, if a number of determinations that the low-pressure side fuel pressure in lower than normal for a first predetermined period of time Range, is equal to or greater than a first predetermined number. Apparatus for diagnosing abnormality of the high-pressure fuel supply system The internal combustion engine according to claim 1 or 2, further characterized marked that the second determining means (S102, S108-S112, S116-S118) determines that the second abnormal operation is introduced, if a number of Provisions that the low-pressure side fuel pressure in one second predetermined period higher is considered the normal range, equals how or gets bigger as a second predetermined number. An apparatus for diagnosing abnormality of the high-pressure fuel supply system of the internal combustion engine according to any one of claims 1 to 3, characterized by further comprising a reducing means (14). 34 ) for reducing a fluctuation of the low-pressure side fuel pressure; and specifying means for determining that the decrease in the output of the low pressure pump ( 12 ) or an abnormality in the reducer ( 34 ) is caused when the first determining means (S102, S108-S115) determines that the first abnormal operation is introduced, and to determine that the abnormality in the reducing means (S102) 34 ) is caused when the second determining means (S102, S108-S112, S116-S118) determines that the second abnormal operation has been introduced. Apparatus for diagnosing abnormality of the high-pressure fuel supply system the internal combustion engine according to any one of claims 1 to 4, further characterized by: warning means (S119, S121) for providing a warning if it is determined that the first abnormal operation or the second abnormal operation introduced is. Apparatus for diagnosing abnormality of the high-pressure fuel supply system The internal combustion engine according to any one of claims 1 to 5, further characterized by an execution device (S120, S122) for execution a failover operation when it is determined that the first abnormal operation or the second abnormal operation is introduced. An apparatus for diagnosing abnormality of the high-pressure fuel supply system of the internal combustion engine according to claim 6, further characterized characterized in that the execution means (S120, S122) in the fail-safe operation, the operation of the low-pressure pump ( 12 ) or the fuel injection by the fuel injection valves ( 31 ) or a flow control valve ( 22 ) continuously opens that a lot of the high pressure pump ( 14 ) per stroke of a piston ( 19 ) of the high-pressure pump ( 14 ) discharged fuel controls.