DE102016110270B4 - fuel filter device - Google Patents

Abstract

A fuel filter device connected to a fuel supply system having a supply pump (12) for discharging a high-pressure fuel for use in combustion in an internal combustion engine, a feed pump (11) for discharging a low-pressure fuel having a lower pressure than the high-pressure fuel toward the feed pump, and a feed valve ( 15) adapted for introducing a part of the low-pressure fuel as a reducing agent into an air outlet path (16a) in the internal combustion engine, the fuel filter device comprising:a main filter (31) arranged in a main path (21a) as a fuel path from the feed pump to of the supply pump and adapted to receive a foreign matter contained in the low-pressure fuel;a sub-filter (32) disposed in a sub-path (22a) branching from the main path at an upstream portion of the main filter for supply of the low-pressure fuel is arranged toward the supply valve and adapted to receive a foreign substance contained in the low-pressure fuel;a main fuel pressure sensor (41) for detecting a main fuel pressure corresponding to a fuel pressure downstream of the main filter in the main path; a sub fuel pressure sensor (42) for detecting a sub fuel pressure corresponding to a fuel pressure downstream of the sub filter in the sub path; anda main pressure loss determining unit (S36) adapted to determine whether the main filter is in an abnormal state based on a difference between the main fuel pressure and the sub fuel pressure detected during a valve closing timing phase of the supply valve State is in which the main filter has a pressure drop that is greater than or equal to a threshold.

Description

The present disclosure relates to a fuel filter device for capturing foreign matter contained in fuel.

The JP 2013-68195 A describes a fuel supply system including a supply pump for discharging high-pressure fuel toward a common rail for use in combustion in an internal combustion engine, and a supply pump for discharging fuel in a fuel tank as low-pressure fuel toward the supply pump. Systems of this type are generally adapted to receive foreign matter contained in the low-pressure fuel through a filter disposed in a fuel path from the feed pump to the feed pump. When the filter has caught a large amount of foreign matter, the filter has a large pressure loss. Therefore, there is a need to replace the filter and perform maintenance on it at regular intervals.

As a purification system for reducing and purifying NOx contained in the exhaust air or exhaust gas, there is a purification system having a catalyst device with a reduction catalyst provided in an air outlet path and an addition valve for introduction and supplying a reducing agent into the air outlet path at its upstream portion of the catalyst device, respectively. Further, in a case where the fuel for use in combustion discharged from the feed pump is used as the reducing agent, the low-pressure fuel is caused to flow from the main path leading to the fuel path from the feed pump toward corresponds to the supply pump, and this is further routed towards the supply valve.

However, in some cases, the air discharge path may be caused to have higher pressures, such as in a case where the internal combustion engine operates under higher loads. In such a case, it is necessary to cause the reducing agent supplied to the supply valve to have a sufficiently higher pressure to introduce the reducing agent into the air discharge path.

On the other hand, in a case where the low-pressure fuel is caused to branch from the main path toward the supply valve, it is necessary to cause the low-pressure fuel to branch from a portion downstream of the filter. When the filter has captured a larger amount of foreign matter and therefore has a larger pressure loss due to clogging of the film, the low-pressure fuel fed to the supply valve is caused to have a lower pressure. Therefore, in the case where the low-pressure fuel is caused to branch off from the main path toward the supply valve as explained above, the low-pressure fuel guided toward the supply valve can be made to have a lower pressure due to the FilteRail pressure loss, which can prevent that the reducing agent is introduced or introduced into the air outlet path.

Furthermore, the DE 10 2014 106 512 A1 a fuel injector having a pressure reducing valve and a fuel return valve. The pressure reducing valve discharges fuel in a common rail as return fuel to a fuel return line. The fuel return valve supplies the returned fuel to a fuel filter when the returned fuel is at a low temperature and to a fuel tank when the returned fuel is at a high temperature. When the recirculated fuel has a temperature lower than a target temperature, an ECU calculates a target flow rate of recirculated fuel discharged from the pressure reducing valve based on a difference between a current temperature and the target temperature of the recirculated fuel. The pressure reducing valve is driven such that the flow rate of the returned fuel becomes equal to the target flow rate. When the current temperature reaches the target temperature, the pressure reducing valve will be closed.

The DE 10 2009 002 945 A1 discloses that a fuel delivery control device for a fuel delivery apparatus for an internal combustion engine includes a pressure sensor. The pressure sensor is provided between a feed pump and a fuel filter, and the pressure sensor outputs a detection signal based on the feed pressure of the feed pump. A value of the delivery pressure of the delivery pump is detected based on the detection signal output by the pressure sensor. A value of the delivery pressure is estimated based on the operational state of the delivery pump. Abnormality of the pressure relief valve is determined based on the detected value of the supply pressure and the estimated value of the supply pressure.

The DE 10 2009 002 737 A1 discloses an ECU which controls a flow rate of fuel delivered from an electric pump to a filter is discharged decreases as the fuel temperature and the fuel pressure in the filter, which are detected by a sensor section, drop. Since a mechanical pump continues to drive without considering the amount of fuel discharged from the electric pump, when the flow rate of the fuel discharged from the electric pump decreases, a suction pressure is generated at the inlet of the filter. The fuel in a recirculation passage is introduced into the filter through a branch passage. As a result, relatively high-temperature fuel is introduced into the filter to melt solidified fuel that has caused clogging of the filter.

In addition, the DE 699 05 945 T2 A method for detecting the fouling of a fuel filter arranged in a fuel supply circuit of an internal combustion engine, between a fuel pressure regulator of the bypass type downstream of the filter which supplies fuel at an applied pressure upstream and towards the engine, and a pump for pumping fuel coming from the tank, which is placed upstream of the filter and which feeds the regulator through the filter, the method comprising at least the steps consisting in: - determining the fuel pressure at the outlet of the pump and equating it with the fuel pressure at inlet of the filter, - determination of the fuel pressure at the outlet of the filter as if it were the pressure applied by the pressure regulator, - determination of the pressure drop of the filter by means of the difference between the pressures at the inlet and outlet of the filter, - comparison of at least one function value of the pressure drop with at least one reference value in order to extract therefrom relative information on the fouling state of the filter, preferably by determining that the filter is fouled if the function value of the pressure drop is greater than at least the reference value.

Further relevant prior art is in the publications JP 2015 - 86 795 A , JP 2014 - 169 662 A , JP 2013 - 227 886 A , JP 2013 - 96 366 A , JP 2012 - 21 480 A , JP 2010 - 106 682 A , JP 2005 - 16 384 A and JP 2004 - 337 668 A disclosed.

It is an object of the present disclosure to provide a fuel filter device capable of reducing the likelihood of a shortage in the pressure of a supplied fuel when the fuel for supplying the fuel as a reducing agent is supplied into an air discharge path toward a supply valve.

In order to achieve the above object, the present disclosure employs the following technical means.

In a first aspect of the present disclosure, there is provided a fuel filter device which is connected to a fuel supply system having a supply pump for discharging a high-pressure fuel for use in combustion in an internal combustion engine, a feed pump for discharging a low-pressure fuel having a lower pressure than the high-pressure fuel to the feed pump, and a supply valve adapted for introducing a part of the low-pressure fuel as a reducing agent into an air discharge path in the internal combustion engine. The fuel filter device includes: a main filter arranged in a main path as a fuel path from the feed pump to the supply pump and adapted to capture a foreign substance contained in the low-pressure fuel; a sub-filter that is arranged in a sub-path branching from the main path at an upstream portion of the main filter for supplying the low-pressure fuel toward the supply valve and adapted to receive foreign matter contained in the low-pressure fuel; a main fuel pressure sensor for detecting a main fuel pressure corresponding to a fuel pressure downstream of the main filter in the main path; a sub fuel pressure sensor for detecting a sub fuel pressure corresponding to a fuel pressure downstream of the sub filter in the sub path; and a main pressure loss determination unit adapted to determine whether the main filter is in an abnormal state based on a difference between the main fuel pressure and the sub fuel pressure detected during a valve closing timing phase of the supply valve , in which the main filter has a pressure drop that is greater than or equal to a threshold value.

In addition to the main filter arranged in the main path to the feed pump, the sub-filter is provided, which is arranged in the sub-path to the feed valve. Further, the sub-path branches from the portion thereof upstream of the main filter. This can prevent the pressure of the fuel supplied to the supply valve from being reduced due to clogging of the main filter.

Further, in the present disclosure, in addition to the main fuel pressure sensor, there is provided the sub fuel pressure sensor which performs the determination of abnormality of the pressure loss (des sub-pressure loss) at the sub-filter based on the detected sub-fuel pressure. This makes it possible to prompt a user to replace the sub-filter before the occurrence of a deficiency in the pressure of the fuel supplied due to clogging of the sub-filter.

Further, in the present disclosure, it is determined whether the main filter is in an abnormal state in which the pressure loss in the main filter ( the main pressure drop) is greater than or equal to the threshold. In this case, the sub fuel pressure detected during a valve closing timing phase of the supply valve is closely related to the pressure upstream of the main filter. In particular, the sub-filter is less likely to be caused to become clogged because the flow rate of fuel flowing through it is smaller than that of the main filter. Therefore, the sub pressure loss is smaller, and thus it can be determined that the sub fuel pressure is strongly related to the pressure upstream of the main filter as described above. Therefore, the difference between the main fuel pressure and the sub fuel pressure is closely related to the main pressure loss. Therefore, according to the present disclosure, in which an abnormality of the main pressure loss is determined based on the aforementioned difference, it is possible to improve the determination accuracy compared to cases of determining abnormalities based on the main fuel pressure without using the sub fuel pressure .

In a second aspect of the present disclosure, there is provided a fuel filter device which is connected to a fuel supply system having a supply pump for discharging a high-pressure fuel for use in combustion in an internal combustion engine, a feed pump for discharging a low-pressure fuel having a lower pressure than the high-pressure fuel to the feed pump, and a supply valve adapted for supplying part of the low-pressure fuel as a reducing agent into an air discharge path in the internal combustion engine. The fuel filter device includes: a main filter arranged in a main path as a fuel path from the feed pump to the supply pump and adapted to capture a foreign substance contained in the low-pressure fuel; a sub-filter that is arranged in a sub-path branching from the main path at an upstream portion of the main filter for supplying the low-pressure fuel toward the supply valve and adapted to receive foreign matter contained in the low-pressure fuel; a main fuel pressure sensor for detecting a main fuel pressure corresponding to a fuel pressure downstream of the main filter in the main path; a sub fuel pressure sensor for detecting a sub fuel pressure corresponding to a fuel pressure downstream of the sub filter in the sub path; and a sub-pressure loss determination unit adapted to determine whether the sub-filter is in an abnormal state based on the main fuel pressure and the sub-fuel pressure detected during a valve-opening timing phase of the supply valve, in which the sub-filter has a pressure drop greater than or equal to a threshold.

According to the present disclosure, besides the main filter arranged in the main path toward the supply pump, the sub-filter arranged in the sub-path toward the supply valve is provided. Further, the sub-path branches from the portion thereof upstream of the main filter. This can prevent the pressure of the fuel sent to the supply valve from being reduced due to clogging of the main filter, and further reduce the likelihood of the pressure of the fuel sent to the supply valve decreasing due to clogging of the sub-filter.

Further, based on the main fuel pressure and the sub fuel pressure detected during a valve opening timing of the supply valve, it is determined whether the sub filter is in an abnormal state in which the sub pressure loss is greater than or equal to the threshold. In this case, the main fuel pressure detected during the valve opening timing of the supply valve is closely related to the pressure upstream of the sub-filter. Further, the difference between the pressure upstream of the sub-filter and the pressure downstream of the sub-filter (the sub-fuel pressure) is strongly related to the sub-pressure loss. Accordingly, it is possible to calculate a physical value that is strongly related to the sub pressure loss based on the main fuel pressure and the sub fuel pressure. Further, it is possible to determine the presence or absence of abnormality of the sub pressure loss based on this physical value with higher accuracy. This can improve the determination accuracy compared to cases of determining abnormalities of the sub pressure loss based on the sub fuel pressure without using the main fuel pressure improve. This makes it possible to accurately prompt the user to replace the sub-filter before the occurrence of a deficiency in the pressure of supply fuel due to clogging of the sub-filter.

In a third aspect of the present disclosure, there is provided a fuel filter device which is connected to a fuel supply system having a supply pump for discharging a high-pressure fuel for use in combustion in an internal combustion engine, a feed pump for discharging a low-pressure fuel having a lower pressure than the high-pressure fuel to the feed pump, and a supply valve adapted for supplying part of the low-pressure fuel as a reducing agent into an air discharge path in the internal combustion engine. The fuel filter device includes: a main filter arranged in a main path as a fuel path from the feed pump to the supply pump and adapted to capture a foreign substance contained in the low-pressure fuel; a sub-filter that is arranged in a sub-path branching from the main path at an upstream portion of the main filter for supplying the low-pressure fuel toward the supply valve and adapted to receive foreign matter contained in the low-pressure fuel; a sub fuel pressure sensor for detecting a sub fuel pressure corresponding to a fuel pressure downstream of the sub filter in the sub path; and a sub pressure loss determination unit adapted to determine whether the sub filter is in an abnormal state based on a change in the sub fuel pressure caused by an opening and closing operation of the supply valve, in which the sub-filter has a pressure drop that is greater than or equal to a predetermined value.

According to the present disclosure, besides the main filter arranged in the main path toward the supply pump, the sub-filter arranged in the sub-path toward the supply valve is provided. Further, the sub-path branches from the portion thereof upstream of the main filter. This can prevent the pressure of the fuel sent to the supply valve from being reduced due to clogging of the main filter, and further reduce the risk of the pressure of fuel sent to the supply valve decreasing due to clogging of the sub-filter.

If valve opening and closing operations of the supply valve are performed, pulsation occurs in the sub fuel pressure. In other words, if a valve-opening operation or a valve-closing operation of the supply valve is performed, pulsation of fuel pressure occurs in the path from the injection hole at the supply valve toward the sub-filter. For example, immediately after the start of a valve-opening operation of the supply valve, the low-pressure fuel is not immediately supplied to the sub-path in an amount corresponding to the amount of fuel supplied from the supply valve (the supply amount or the supply amount), resulting in a temporary decrease in the Sub fuel pressure immediately after the start of the valve opening operation. Further, the low-pressure fuel is not immediately decreased in amount immediately after the start of a valve-closing operation of the supply valve, and the low-pressure fuel is continuously supplied due to inertia. This leads to a temporary increase in the sub fuel pressure immediately after the start of the valve closing operation. Further, the aforesaid temporary decrease and increase are varied depending on the magnitude of the sub-pressure loss in terms of speed, time phase, and the like. Therefore, the sub-pressure loss is strongly related to the above waveform.

• 1 ist eine schematische Ansicht, welche eine Kraftstofffiltervorrichtung und ein Kraftstoffsystem, welches die Vorrichtung einsetzt, gemäß einer ersten Ausführungsform der vorliegenden Offenbarung darstellt.
• 2 ist ein Flussdiagramm, welches den Verarbeitungsablauf zum Steuern von Betätigungen einer Zuführpumpe und einer Förderpumpe gemäß der ersten Ausführungsform darstellt.
• 3 ist ein Flussdiagramm, welches den Verarbeitungsablauf zum Steuern von Betätigungen eines Zuführventils gemäß der ersten Ausführungsform darstellt.
• 4 ist eine Ansicht, welche die Differenz zwischen einem Haupt-Kraftstoffdruck und einem Sub-Kraftstoffdruck in einem Zustand darstellt, bei welchem diese im Zeitverlauf verändert werden, gemäß der ersten Ausführungsform.
• 5 ist ein Flussdiagramm, welches den Verarbeitungsablauf zum Diagnostizieren des Vorliegens oder Nichtvorliegens einer Anomalie bei einem Haupt-Druckverlust gemäß der ersten Ausführungsform darstellt.
• 6 ist ein Flussdiagramm, welches den Verarbeitungsablauf zum Diagnostizieren des Vorliegens oder Nichtvorliegens einer Anomalie bei dem Haupt-Druckverlust gemäß einer zweiten Ausführungsform der vorliegenden Offenbarung darstellt.
• 7 ist ein Flussdiagramm, welches den Verarbeitungsablauf zum Diagnostizieren des Vorliegens oder Nichtvorliegens einer Anomalie bei einem Sub-Druckverlust gemäß einer dritten Ausführungsform der vorliegenden Offenbarung darstellt.
• 8 ist eine Ansicht, welche die Veränderung des Sub-Kraftstoffdrucks, welche durch Öffnungs- und Schließbetätigungen des Zuführventils hervorgerufen wird, gemäß einer vierten Ausführungsform der vorliegenden Offenbarung darstellt.
• 9 ist ein Flussdiagramm, welches den Verarbeitungsablauf zum Diagnostizieren des Vorliegens oder Nichtvorliegens einer Anomalie bei dem Sub-Druckverlust gemäß der vierten Ausführungsform darstellt.
• 10 ist ein Flussdiagramm, welches den Verarbeitungsablauf zum Diagnostizieren des Vorliegens oder Nichtvorliegens einer Anomalie bei dem Sub-Druckverlust gemäß einer fünften Ausführungsform der vorliegenden Offenbarung darstellt.

In the third aspect of the present disclosure, it is determined whether the sub-filter is in an abnormal state in which the sub-pressure loss is larger than or not based on the change in the sub-fuel pressure caused by opening and closing operations of the supply valve is equal to a predetermined value. This enables the user to be prompted to replace the sub-filter exactly before there is a deficiency in the pressure of the fuel passed through it due to clogging of the sub-filter.

• 1 12 is a schematic view illustrating a fuel filter device and a fuel system employing the device according to a first embodiment of the present disclosure.
• 2 14 is a flowchart showing the flow of processing for controlling operations of a supply pump and a discharge pump according to the first embodiment.
• 3 14 is a flowchart showing the flow of processing for controlling operations of a supply valve according to the first embodiment.
• 4 12 is a view showing the difference between a main fuel pressure and a sub fuel pressure in a state in which these are changed with the passage of time according to the first embodiment.
• 5 14 is a flowchart showing the flow of processing for diagnosing the presence or absence of an abnormality in a main pressure loss according to the first embodiment.
• 6 14 is a flowchart showing the flow of processing for diagnosing the presence or absence of an abnormality in the main pressure loss according to a second embodiment of the present disclosure.
• 7 14 is a flowchart showing the flow of processing for diagnosing the presence or absence of an abnormality in sub pressure loss according to a third embodiment of the present disclosure.
• 8th 14 is a view illustrating the change in sub fuel pressure caused by opening and closing operations of the supply valve according to a fourth embodiment of the present disclosure.
• 9 14 is a flowchart showing the flow of processing for diagnosing the presence or absence of an abnormality in the sub pressure loss according to the fourth embodiment.
• 10 14 is a flowchart showing the flow of processing for diagnosing the presence or absence of an abnormality in the sub pressure loss according to a fifth embodiment of the present disclosure.

A plurality of embodiments are described below with reference to the figures. In each of the embodiments, parts corresponding to items described in the previous embodiments are denoted by the same reference numerals, and these may not be described repeatedly in some cases. In each of the embodiments, when structures are described only in terms of portions thereof, the other embodiments described above may be applied to the other portions of the structures by reference thereto.

(First embodiment)

1 shows a fuel supply system for supplying a fuel for use in combustion in an internal combustion engine carried on a vehicle, and a purification system for reducing and purifying NOx emitted from the internal combustion engine.

A compression self-ignition diesel engine is used as the internal combustion engine, and a fuel having compression self-ignition ability such as light oil is used as the fuel for use in combustion.

The fuel supply system includes a fuel tank 10, a feed pump 11, a feed pump 12, a common rail 13, and fuel injection valves 14 and the like. A liquid fuel in the fuel tank 10 is fed by the feed pump 10 arranged in the fuel tank 10 and fed towards the feed pump 12 . The supplied fuel is compressed by the supply pump 12 and then transferred to the common rail 13 . For example, a gear pump is used as the feed pump 11 . Specifically, a trochoid type or vane type internal gear pump is used as the feed pump 11 . A plunger type pump is used as the feed pump 12 .

The feed pump 11 operates by an unillustrated electric motor as a driving power source. The feed pump 12 operates by the rotational force corresponding to a driving power source, an output shaft of the internal combustion engine. The fuel discharged from the feed pump 12 (the high-pressure fuel) has a higher pressure than the fuel discharged from the feed pump 11 (the low-pressure fuel). The feed pump 12 includes an unillustrated control valve. This control valve adjusts the amount of low-pressure fuel drawn into and through the piston (the suction amount). Therefore, the amount of high-pressure fuel discharged from the piston is adjusted. Further, the remainder of the fuel, which is supplied from the feed pump 11 and differs from the suction amount, is returned to the fuel tank 10 via a return pipe 24 .

The high-pressure fuel discharged from the supply pump 12 is received by the common rail 13 and then supplied to the plurality of fuel injection valves 14 and distributed. The distributed high-pressure fuel is injected into the combustion chamber in the internal combustion engine via injection holes in the fuel injection valves 14 by the valve opening operation of the fuel injection valves 14 . The injected fuel is mixed with an intake air to form an air-fuel mixture and this Air-fuel mixture is compressed to burn through auto-ignition in the combustion chamber. The exhaust air or exhaust gas caused by the combustion is cleaned by the aforementioned cleaning system.

The cleaning system includes an addition valve 15, a cleaning device 17 and the like. The cleaning device 17, which is mounted at an air outlet duct 16, comprises a reduction catalyst. The supply valve 15 is mounted on the air discharge duct 16 at its portion on the upstream side of the discharge air flow with respect to the cleaning device 17 . The supply valve 15 supplies a reducing agent into an air discharge path 16a. The supply valve 15 comprises an electric actuator 15a and a valve body 15b. If the energization to the electric actuator 15a is turned on, the valve body 15b performs a valve opening operation, whereby the reducing agent is injected (added) via an injection hole at the supply valve 15 into the air discharge path 16a. If the energization to the electric actuator 15a is cut off, the valve body 15b performs a valve closing operation, thereby stopping injection through the injection hole. The added reducing agent flows into the purification device 17 together with the exhaust air and reduces NOx contained in the exhaust air at the reduction catalyst. As the reducing agent supplied from the supply valve 15 into the air outlet path 16a, the fuel for use in combustion in the internal combustion engine, that is, the fuel in the fuel tank 10 is used.

In the following description, the fuel path from the feed pump 11 to the supply pump 12 is referred to as a main path 21 a , and the pipe forming the main path 21 a inside is referred to as a main pipe 21 . A main filter 31 for capturing foreign matter contained in the low-pressure fuel is mounted on the main pipe 21 .

A branch line 22 forming a sub-path 22a inside is connected to the portion of the main line 21 upstream of the main filter 31. As shown in FIG. Therefore, part of the low-pressure fuel discharged from the feed pump 11 branches off from the main path 21a and flows through the sub-path 22a. A sub-filter 32 for capturing foreign matter contained in the low-pressure fuel is mounted on the branch pipe 22 . The aforesaid supply valve 15 is connected to the portion of the branch line 22 downstream of the sub-filter 32 .

In other words, part of the fuel delivered by the feed pump 11 is routed through the main path 21a to the fuel injection valves 14 and then used as the fuel for combustion, while the other part of the fuel is routed through the sub-path 22a to the supply valve 15 is passed and then used as the reducing agent. The amount of fuel supplied from the supply valve 15 is smaller than the amount of fuel injected from the fuel injection valves 14 . Therefore, the branch line 22 is constructed by a narrower line than the main line 21, and the sub-filter 32 is constructed by a smaller filter than the main filter 31. FIG. Specifically, the filtering area of the sub-filter 32 is smaller than the filtering area of the main filter 31. Further, the sub-filter 32 can capture a smaller amount of foreign matter than the main filter 31 captures. The main filter 31 has a function of removing moisture contained in the fuel, while the sub-filter 32 has no moisture removing function.

A main fuel pressure sensor 41 is mounted at the portion of the main line 21 downstream of the main filter 31 and a sub fuel pressure sensor 42 is mounted at the portion of the branch line 22 downstream of the sub filter 32 . The fuel pressure downstream of the main filter in the main path 21 a is referred to as a main fuel pressure P1 , and this main fuel pressure P1 is detected by the main fuel pressure sensor 41 . Further, the fuel pressure downstream of the sub-filter 32 in the sub-path 22a is referred to as a sub-fuel pressure P2, and this sub-fuel pressure P2 is detected by the sub-fuel pressure sensor 42. FIG.

An ECU 50, which corresponds to an electronic control device, includes a microcomputer including a memory and a CPU. The CPU performs operation processing according to programs stored in the memory, which causes the ECU 50 to control the operation of the feed pump 11, the feed pump 12, the fuel injection valves 14 and the feed valve 15. Further, signals of values detected by the main fuel pressure sensor 41, the sub fuel pressure sensor 42, a rail pressure sensor 13a and a discharge air temperature sensor 16b are input to the ECU 50. The rail pressure sensor 13a detects the pressure of the fuel which was taken in under pressure through the common rail 13 . The outlet air temperature sensor 16b detects the outlet air temperature, which corresponds to the temperature of the inside of the air outlet path 16a.

2 represents the flow of processing by the microcomputer used to control the Operation of the feed pump 12 and the feed pump 11 is used. The processing in 2 is repeatedly executed at a predetermined cycle time during operation of the internal combustion engine.

At step S10 in 2 a physical value is first obtained which indicates the operating state of the internal combustion engine. This physical value may correspond to the engine speed NE, which indicates the speed of the output shaft of the internal combustion engine, the engine load such as the depression amount of an accelerator pedal, and the like. At step S11, a target rail pressure PCtrg is calculated based on the engine speed NE obtained at step S10. For example, the target rail pressure PCtrg is set to a larger value as NE and the load are larger.

At step S12, the actual rail pressure PCact, which corresponds to the value detected by the rail pressure sensor 13a, is obtained and the supply pump 12 is controlled by feedback so that the actual rail pressure PCact is equal to the target rail pressure PCtrg. Specifically, a target intake amount by the aforementioned shift valve is calculated based on the deviation of the actual rail pressure PCact from the target rail pressure PCtrg. Further, the ECU 50 controls the operation of the shift valve to achieve the target suction amount, which controls the amount of high-pressure fuel discharged from the supply pump 12, thereby controlling the actual rail pressure PCact to be equal to the target rail pressure PCtrg.

At step S<b>13 , the operation of the feed pump 11 is controlled according to the content of the control of the feed pump 12 . Specifically, the amount of electric power supplied to the feed pump 11 is controlled based on the target suction amount with respect to the variable valve. For example, the ECU 50 calculates the target delivery amount of the delivery pump 11 based on the target suction amount, and outputs a duty signal to a driver 53 in response to the target delivery amount. The driver 53 controls the energization of the feed pump 11 based on the duty signal or switch-on signal, as a result of which the amount of electrical power that is fed to the feed pump 11 is controlled.

3 Fig. 12 shows the flow of processing by the microcomputer used to control the operation of the supply valve. The processing in 3 is repeatedly executed at a predetermined time cycle during the operation of the internal combustion engine under the condition that the temperature of the reduction catalyst is equal to or higher than the activation temperature. Further, the temperature of the reduction catalyst can be estimated based on the exhaust air temperature detected by the exhaust air temperature sensor 16b.

First, at step S20 in 3 obtains a physical value indicative of the operational state of the internal combustion engine, such as the engine speed NE or the engine load. At step S21, the amount of NOx in the exhaust air discharged per a predetermined period of time is estimated based on the physical value obtained at step S20. At step S22, a target supply amount Qtrg of the reducing agent is calculated based on the amount of NOx estimated at step S21. At step S23, the operation of the delivery valve 15 is controlled based on the target delivery amount Qtrg calculated at step S22. Specifically, the ECU 50 controls the timing during which energization to the aforesaid electric actuator 15a is On according to the target supply amount Qtrg, thereby controlling the amount of the reducing agent supplied per a predetermined timing.

The ECU 50 estimates the pressure loss (the main pressure loss ΔP1) in the main filter 31 and the pressure loss (the sub pressure loss ΔP2) in the sub filter 32 based on the main fuel pressure P1 and the sub fuel pressure P2, which are the main fuel pressure sensor 41 and the sub fuel pressure sensor 42 have been detected. Further, the microcomputer serves as a main pressure loss estimating unit 51 when estimating the main pressure loss ΔP1 (see FIG 1 ). The microcomputer serves as a sub pressure loss estimating unit 52 when estimating the sub pressure loss ΔP2.

The sub-pressure loss estimating unit 52 obtains the flow rate of fuel fed from the feed pump 11 to the sub-filter 32 (the branch flow rate) during a valve opening timing of the supply valve 15. The branch flow rate is calculated based on the operating states of the feed pump 12 and the feed pump 11 is estimated. Specifically, the discharge amount from the feed pump 11 is calculated based on the duty signal (the command signal) output from the ECU 50 to the driver 53 . On the other hand, the suction amount into the supply pump 12 is calculated based on the command signal output from the ECU 50 to the variable valve. Further, the flow rate of the fuel fed to the sub-filter 32 is obtained by subtracting the above th intake amount is calculated from the aforementioned delivery amount.

Further, the sub pressure loss estimating unit 52 acquires the sub fuel pressure P2 detected by the sub fuel pressure sensor 42 during the valve opening timing phase of the supply valve 15. Further, the sub pressure loss estimating unit 52 estimates the sub pressure loss ΔP2 based on the branch flow rate and the sub-fuel pressure P2 which have been obtained. For example, the values of the sub pressure losses ΔP2 with respect to branch flow rates and sub fuel pressures P2 are mapped in advance through experiments. Further, the sub pressure loss ΔP2 is calculated with respect to the branch flow rate and the sub fuel pressure P2 obtained with reference to the map. Alternatively, a calculation formula for calculating the sub pressure loss ΔP2 from the branch flow rate and the sub fuel pressure P2 is stored in advance. Thereafter, the branch flow rate and the sub fuel pressure P2 obtained are substituted into the calculation formula to calculate the sub pressure loss ΔP2.

If the sub pressure loss ΔP2 estimated by the sub pressure loss estimating unit 52 is greater than or equal to a predetermined threshold value set in advance, the ECU 50 determines that the sub filter 32 is in an abnormal state in which the Degree of clogging of the sub-filter 32 due to foreign matter received in the sub-filter 32 has reached a limit. If such an abnormality is determined, a warning lamp is lit or a warning sound is emitted to prompt a user to replace the sub-filter 32.

The main pressure loss estimating unit 51 estimates the main pressure loss ΔP1 based on the difference ΔP1 between the main fuel pressure P1 and the sub fuel pressure P2 detected during the valve closing timing phase of the supply valve 15 . During the valve closing phase of the supply valve 15, the sub fuel pressure P2 can be considered to be substantially equal to the upstream side pressure Pu of the main filter 31. Therefore, it is possible to estimate that the aforesaid difference ΔP1 corresponds to the main pressure loss ΔP1.

In 4(a) a solid line indicates the sub fuel pressure P2, a broken line indicates the main fuel pressure P1, and the difference between them corresponds to the main pressure loss ΔP1. 4(b) 14 illustrates a valve opening start time ts and a valve closing time te with respect to the supply valve 15, the time phase from the valve opening start time ts to the valve closing time te corresponding to the valve opening time phase.

5 Fig. 12 shows the flow of processing by the microcomputer for generating a warning to the user in an abnormal condition where the main pressure loss ΔP1 is greater than or equal to a threshold. This processing in 5 is repeatedly executed at a predetermined time cycle during the operation of the internal combustion engine.

At step S30 in 5 it is first determined whether there is a request to open the supply valve 15. For example, when the supply valve 15 at step S23 in 3 is controlled to be opened, it is determined that there is an add-on request. If it is determined that there is no request for addition, that is, if the supply valve 15 is in a valve-closed state, it is determined at step S31 whether the present time falls in a transient period of time immediately after the valve is closed.

In this case, if valve opening and closing operations of the supply valve 15 are performed as shown in FIG 4(a) indicated by a reference character Ta, a pulsation of the sub-fuel pressure P2 occurs. In other words, if valve opening and closing operations of the supply valve 15 are performed, pulsation occurs in the path from the injection hole at the supply valve 15 toward the sub-filter 32 . For example, immediately after the start of a valve-opening operation of the supply valve 15, the low-pressure fuel is not immediately supplied to the sub-path 22a in an amount responsive to the fuel amount (the supply amount) supplied from the supply valve 15, causing a temporary decrease in the sub-fuel pressure immediately after the valve opening start time ts. Further, the low-pressure fuel supplied to the path is not immediately reduced in amount immediately after the valve closing time te, and the low-pressure fuel is continuously supplied due to inertia. This leads to a temporary increase in the sub fuel pressure immediately after the valve closing time te. Therefore, pulsation occurs at the sub-fuel pressure P2 in the time period indicated by reference character Ta (the transient time period). This transient time Ta corresponds to a time including the supply time from the valve opening start time ts to the valve closing time te, and a time from the valve closing time te to an elapse of a predetermined time, and the pre- called pulsation occurs noticeably in this time phase.

In view of this fact, it is determined at step S31 whether the present time falls within the transition period Ta. If it is determined that the present time does not fall within the transient period of time Ta, the discharge flow rate Qf from the feed pump 11, the main fuel pressure P1, and the sub fuel pressure P2 are obtained at step S32. As the main fuel pressure P1 and the sub fuel pressure P2, the values detected by the main fuel pressure sensor 41 and the sub fuel pressure sensor 42 are used. The discharge flow rate Qf is calculated based on the control content of the feed pump 11 at step S13 in FIG 2 estimated.

4(c) 12 illustrates the change in the discharge flow rate Qf, indicating that a change in the discharge flow rate Qf causes a change in the value of the main pressure loss ΔP 1 even with the same degree of clogging of the main filter 31. In other words, as in 4(a) and 4(c) 1, the difference between the main fuel pressure P1 and the sub fuel pressure P2 has a smaller value as the discharge flow rate Qf is smaller. Accordingly, the accuracy of estimating the main pressure loss ΔP1 is deteriorated as the discharge flow rate Qf is smaller.

In view of this fact, it is determined at step S33 whether the discharge flow rate Qf estimated at step S32 is greater than or equal to a threshold value Qth. If it is determined that the discharge flow rate Qf is greater than or equal to the threshold value Qth, a threshold value TH1 is set based on the discharge flow rate Qf at step S34. At step S35, the difference ΔP1 (the main pressure loss) between the sub fuel pressure P2 and the main fuel pressure P1 obtained at step S32 is calculated. At step S36, it is determined whether the difference calculated at step S35 is greater than or equal to the threshold value TH1 set at step S34. If it is determined that the relationship ΔP1 ≥ TH1 is satisfied, it is judged at step S37 that the main filter 31 is in an abnormal state in which the degree of clogging of the main filter 31 due to foreign matter received therein has reached a limit, and will a main pressure loss anomaly flag is set to On. At step S38, a warning lamp is lit or a warning sound is emitted to prompt the user to replace the main filter 31.

When the main filter 31 has been replaced with a new one, it is determined at step S36 that the relationship P1<TH1 is satisfied. In this case, the main decompression anomaly flag is set to off at step S39, which prevents the warning from being generated for the user. Furthermore, the processing in 5 ends without performing the processings at steps S34 to S39 in the cases described below, which include a case where it is determined at step S30 that there is a request for addition, a case where it is determined at step S31 that the present time falls within the transition period Ta, and a case where it is determined at step S33 that the discharge flow rate Qf is smaller than the threshold value Qth.

As described above, the fuel filter device according to the present embodiment includes the main filter 31, the sub-filter 32, the main fuel pressure sensor 41, the sub fuel pressure sensor 42, and a main pressure loss determination unit. In other words, besides the main filter 31 arranged in the main path 21a toward the supply pump 12, the sub-filter 32 arranged in the sub-path 22a toward the supply valve 15 is provided. Further, the sub-path 22a branches from the portion upstream of the main filter 31. FIG. This can prevent the pressure of the fuel supplied to the supply valve 15 from being reduced due to clogging of the main filter 31 .

Further, the consumption of the fuel fed to the feed pump 12 in a conventional internal combustion engine, that is, the consumption of the fuel for use in combustion, is much larger in amount than the consumption of the fuel used as the reducing agent. Further, according to the present embodiment, the fuel supplied to the supply pump 12 does not pass through the sub-filter 32 . This reduces the risk of clogging of the sub-filter 32 compared to that of the main filter 31 the replacement frequency of the main filter can be reduced. Further, the sub-filter 32 is expected to be checked in the event of the main filter 31 replacement. This can reduce the likelihood of shortfall in the supply fuel pressure due to non-performance of sub-filter 32 checks.

Further, in the present embodiment, in addition to the main fuel pressure sensor 41, the sub fuel pressure sensor 42 is provided, which makes it possible to detect an abnormality in pressure loss (the sub pressure loss) at the sub filter 32 based on the detected sub fuel pressure. This makes it possible to prompt the user to replace the sub-filter 32 before occurrence of shortage of the pressure of the supplied fuel due to clogging of the sub-filter 32 .

Further, in the present embodiment, the main pressure loss determination unit is provided, which is adapted to be based on the difference ΔP 1 between the main fuel pressure P1 and the sub fuel pressure P1 detected during the valve closing timing phase of the supply valve 15. determines whether the main pressure loss is in an abnormal state in which the main pressure loss ΔP1 is greater than or equal to the threshold TH1. This main pressure loss determining unit is provided by the microcomputer which executes the processing at step S36 in FIG 5 executes The sub fuel pressure P2 detected during the valve closing timing phase of the supply valve 15 is closely related to the upstream side pressure Pu of the main filter 31 . Therefore, the difference between the main fuel pressure P1 and the sub fuel pressure P2 is strongly related to the main pressure loss ΔP1. Therefore, according to the present embodiment in which an abnormality of the main pressure loss is determined based on the aforesaid difference ΔP1, it is possible to improve the accuracy of the abnormality determination compared to the case of determining abnormalities based on the main fuel pressure P1 without using the to improve sub-fuel pressure P2.

In the present embodiment, due to the provision of the sub fuel pressure sensor 42, it is possible to determine the presence or absence of an abnormality in the sub pressure loss ΔP2 based on the detected sub fuel pressure P2. In other words, it can be said that the accuracy of determining an abnormality of the main pressure loss using the detected value of the sub fuel pressure P2 for use in the sub pressure loss abnormality determination is improved.

Further, in the present embodiment, there is provided a transient time preventing unit adapted to prohibit the aforesaid abnormality determination also in the valve closing timing in the transient timing Ta from the start of closing of the supply valve 15 to the elapse of the predetermined timing. The transition time prohibition unit is provided by the microcomputer which executes the processing at step S31 in 5 executes This prevents an abnormality determination from being performed by obtaining the aforesaid difference ΔP1 in states where there is a large influence of the pulsation of the sub fuel pressure P2 in the transient time phase Ta, which can further improve the accuracy of the abnormality determination.

Further, in the present embodiment, there is provided a low flow rate time preventing unit which is adapted to prohibit the aforesaid abnormality determination also in a valve closing time phase if the flow rate of the low pressure fuel is lower than a predetermined value. The low flow rate time preventing unit is provided by the microcomputer executing the processing at step S34 in FIG 5 executes This prevents the abnormality determination from being performed by obtaining the aforementioned difference ΔP1 in low flow rate states where the discharge flow rate Qf from the feed pump 11 is smaller, which can further improve the accuracy of the abnormality determination.

(Second embodiment)

In the present embodiment, the flowchart is in FIG 5 according to the first embodiment to an in 6 shown flowchart remodeled. Further, in the present embodiment, the same control as the control in FIG 2 and 3 performed according to the first embodiment.

At step S310 in 6 first, it is determined whether a request has been made to diagnose whether the main pressure loss ΔP 1 is in an abnormal state. For example, the cumulative distance that the vehicle has traveled since a previous diagnosis was run is stored and updated. If the cumulative mileage reaches a predetermined value, a request to perform diagnosis is made. When the diagnostic is run, the cumulative mileage is reset to zero. Alternatively, the cumulative amount of reductant added since a previous diagnosis was performed may be stored and updated. If the cumulative amount of added reductant reaches a predetermined value, a request to perform a diagnosis may be made.

If it is determined that a request for diagnosis has been made, the same processing as steps S30 and S31 in FIG 5 performed, and if there is no request to add and also the present time does not fall within the transition time phase, the operation proceeds to the processing at step S320. At step S320, the target delivery amount of the feed pump 11 is forcibly changed to a value greater than or equal to a predetermined value set in advance (a determination control value) regardless of the step S13 in FIG 2 set value of the target funding amount. In other words, the feed pump 11 is controlled to achieve a discharge amount greater than or equal to the determination control value regardless of the target suction amount by the variable valve in the supply pump 12 . It is necessary to set the determination control value to be a sufficiently larger value, and the determination control value is set to a maximum value that falls within the specifications of the feed pump 11, for example.

After the processing at step S320, in a manner similar to steps S35 to S39 in 5 the main pressure drop ΔP1 is calculated. If ΔP1 is greater than or equal to the threshold TH1, an anomaly is determined and a warning is generated for the user. When processing in 5 the threshold value TH1 for the determination is changed depending on the discharge flow rate Qf. In contrast, the threshold value TH1 for the determination in the present embodiment is set to be a value according to the determination control value, and therefore is not changed depending on the discharge flow rate Qf.

As described above, in the present embodiment, there is provided a feed pump control unit which is adapted to calculate the target flow rate of the low-pressure fuel from the feed pump 11 based on the amount of high-pressure fuel to be supplied to the internal combustion engine, and further calculates such is adapted to control the operation of the feed pump 11 according to the target flow rate. Further, there is provided a determination pump control unit adapted to forcibly set the flow rate of the low-pressure fuel to a predetermined value or greater regardless of the target flow rate of the feed pump control unit. The feed pump control unit is provided by the microcomputer which executes the processing at step S13 in 2 executes The determination pump control unit is provided by the microcomputer executing the processing at step S320 in FIG 2 executes

In this case, the estimation accuracy of the main pressure loss ΔP1 is deteriorated as the discharge flow rate Qf from the feed pump 11 becomes lower, as with reference to FIG 4 is described. In view of this fact, according to the present embodiment, even if a small amount of the high-pressure fuel is to be supplied to the feed pump 12 and the target delivery amount of the delivery pump 11 is smaller, the discharge amount from the delivery pump 11 at the time becomes an abnormality diagnosis mandatory controlled to be greater than or equal to the predetermined value. This can further improve the accuracy of the anomaly determination.

(Third embodiment)

The sub pressure loss estimating unit 52 according to the first embodiment is adapted to determine the presence or absence of an abnormality in the sub filter 32 by estimating the sub pressure loss ΔP2 based on the branch flow rate and the sub fuel pressure P2 during a Valve opening time phase of the supply valve 15 diagnosed. In the present embodiment, on the other hand, the presence or absence of an abnormality in the sub-filter 32 is diagnosed by estimating the sub-pressure loss ΔP2 based on the main fuel pressure P1 and the sub-fuel pressure P2 detected during a valve opening timing phase of the supply valve 15 . In particular, processing in 7 , which will be described later, is executed by the microcomputer. This processing in 7 is repeatedly executed at a predetermined time cycle during the operation of the internal combustion engine. Further, in the present embodiment, the same control as the control in FIG 2 and 3 carried out according to the aforesaid first embodiment.

At step S40 in 7 it is first determined whether there is a request to open the supply valve 15. The determination is made, for example, in a similar manner to step S30 in FIG 5 carried out. If it is determined that there is a request for introduction, that is, if the supply valve 15 is in an open valve state, the flow rate of fuel flowing through the main filter 31 (the main flow rate Q1), the Main fuel pressure P1 and the main pressure loss ΔP 1 are obtained. As the main fuel pressure P1, the value detected by the main fuel pressure sensor 41 is used. The main flow rate Q1 is calculated based on the content of the control of the feed pump 12 at step S12 in FIG 2 estimated. For example, the target suction amount by the aforementioned variable valve is regarded as the main flow rate Q1. Alternatively, the main flow rate Q1 based on the content of the control of the delivery pump 11 in at step S13 2 estimated. For example, the value resulting from subtracting the feed amount from the target feed amount is regarded as the main flow rate Q1. The main pressure loss ΔP1 can be estimated based on the difference ΔP 1 between the main fuel pressure P1 and the sub fuel pressure P2 detected during a valve closing timing phase of the supply valve 15 in a similar manner to the above-mentioned first embodiment.

At step S42, the upstream pressure Pu of the main filter 31 is calculated based on the main fuel pressure P1, the main pressure loss ΔP1 and the main flow rate Q1 obtained at step S41. For example, a calculation formula for calculating the upstream side pressure Pu from the main fuel pressure P1, the main pressure loss ΔP 1 and the main flow rate Q1 is stored in advance. Further, the main fuel pressure P1, the main pressure loss ΔP1, and the main flow rate Q1, which have been obtained, are substituted into the calculation formula to calculate the upstream-side pressure Pu.

At step S43, the sub fuel pressure P2 and the branch flow rate Q2 are obtained. As the sub fuel pressure P2, the value detected by the sub fuel pressure sensor 42 is used. The branch flow rate Q2 is calculated based on the sub fuel pressure P2 and the opening area of the injection hole at the supply valve 15.

At step S44, the sub pressure loss ΔP2 is calculated based on the sub fuel pressure P2 and the branch flow rate Q2 obtained at step S43 and based on the upstream side pressure Pu calculated at step S42. For example, a calculation formula for calculating the sub pressure loss ΔP2 from the sub fuel pressure P2, the branch flow rate Q2, and the upstream side pressure Pu is stored in advance. Further, the sub fuel pressure P2, the branch flow rate Q2, and the upstream side pressure Pu, which have been obtained, are substituted into the calculation formula to calculate the sub pressure loss ΔP2.

At step S45, it is determined whether the sub pressure loss ΔP2 calculated at step S44 is greater than or equal to a predetermined threshold TH2. If it is determined that the relationship ΔP2 ≥ TH2 is satisfied, it is judged at step S46 that the sub-filter 32 is in an abnormal state in which the degree of clogging of the sub-filter 32 due to foreign matters received therein has reached a limit has reached, and a sub pressure loss abnormality flag is set to On. At step S47, a warning lamp is lit or a warning sound is emitted to prompt the user to replace the sub-filter 32.

When the sub-filter 32 has been replaced with a new one, it is determined at step S45 that the relationship ΔP2 < TH2 is satisfied. In this case, the sub pressure loss anomaly flag is set to off at step S48, preventing the warning from being generated for the user. Furthermore, the processing 7 ends without performing the processing at steps S41 to S48 when it is determined at step S40 that there is a request for injection.

As described above, the fuel filter device according to the present embodiment includes the main filter 31, the sub filter 32, the main fuel pressure sensor 41, the sub fuel pressure sensor 42, and a sub pressure loss determination unit. This sub pressure loss determining unit is provided by the microcomputer which executes the processing at step S45 in 7 executes The sub pressure loss determining unit is adapted to determine whether the sub pressure loss is in an abnormal state based on the main fuel pressure P1 and the sub fuel pressure P2 detected during the valve opening timing phase of the supply valve 15. at which the sub-pressure loss ΔP2 is greater than or equal to the threshold TH2.

The main fuel pressure P 1 detected during the valve opening timing of the supply valve 15 is closely related to the upstream pressure Pu of the main filter 31, that is, the upstream pressure Pu of the sub-filter 32. Furthermore, the difference between the upstream pressure Pu and the Sub fuel pressure P2 is strongly related to the sub pressure loss ΔP2. Accordingly, it is possible to estimate the sub pressure loss ΔP2 with higher accuracy based on the main fuel pressure P1 and the sub fuel pressure P2, and therefore it is possible to determine the presence or absence of an abnormality in the sub pressure loss with higher accuracy . Accordingly, in the present embodiment, it is possible to improve the accuracy of the determination compared to the case of determining abnormalities in the sub pressure loss ΔP2 based on the sub fuel pressure P2 without using the main fuel pressure P1.

Further, in the present embodiment, due to the provision of the main fuel pressure sensor 41, it is possible to determine the presence or absence of an abnormality in the main pressure loss ΔP1 based on the detected main fuel pressure P1. In other words, it can be said that the accuracy of determining abnormalities in the sub pressure loss using the detected value of the main fuel pressure P1 for use in the main pressure loss abnormality determination is improved.

(Fourth embodiment)

As indicated by reference Ta in 4(a) is indicated, pulsation occurs at the sub-fuel pressure P2 if opening and closing operations of the supply valve 15 are performed as described above. In the present embodiment, based on a fuel pressure waveform indicative of this pulsation, it is determined whether the sub pressure loss is in an abnormal state in which the sub pressure loss ΔP2 is greater than or equal to a predetermined value. Further, the estimation of the sub pressure loss ΔP2 is not performed in the present embodiment. Furthermore, in the present embodiment, the same control as the control in FIG 2 and 3 carried out according to the aforesaid first embodiment.

8(a) represents the change in engine speed NE, 8(b) represents the aforementioned pulsation, that is, the fuel pressure waveform of the sub fuel pressure P2, and 8(c) represents the valve opening start time ts and the valve closing time te of the supply valve 15. In the example of FIG 8th the engine speed NE increases in a period of time denoted by a reference character Tc accompanying the start of the operation of the internal combustion engine. Then, after the lapse of a period of time denoted by a reference character Td, at a point of time (the valve opening start time ts) when the reduction catalyst temperature has reached the activation temperature, the addition of the reducing agent is started.

At a change point A1 in the fuel pressure waveform, the fuel pressure starts to decrease accompanying the start of the valve opening (lifting) operation of the valve body 15b in the supply valve 15. Thereafter, the fuel pressure returns at a change point A2 after the lift amount of the valve body 15b has been maximized. from the decreasing trend to an increasing trend. Thereafter, the fuel pressure stops increasing at a change point A3, and the fuel pressure is maintained at a constant value up to a change point A4. After that, the fuel pressure starts to increase along with the start of a valve-closing (descending) operation of the valve body 15b. Thereafter, the fuel pressure reverses from the increasing tendency to the decreasing tendency at a changing point A5 after the lift amount of the valve body 15 becomes zero to complete the closing of the valve. Thereafter, the fuel pressure is maintained at the same value as that at the changing point A1.

During the period of time from the changing point A1 to the changing point A2, the phenomenon of a temporary decrease in fuel pressure due to fuel injection through the injection hole at the supply valve 15 occurs. This corresponds to a phenomenon caused by the fact that the fuel discharged from the feed pump 11 is not immediately supplied to the vicinity of the injection hole. During the period of time from the changing point A2 to the changing point A3, since the amount of fuel injected through the injection hole has been compensated by the fuel from the feed pump 11, the phenomenon of an increase in fuel pressure occurs. During the period of time from the changing point A3 to the changing point A4, there occurs the phenomenon that the fuel pressure is maintained at a constant value (a holding fuel pressure Pb) because the amount of fuel injected through the injection hole and the amount of fuel supplied from the feed pump 11 were compensated.

However, the amount of fuel injected through the injection hole, when the sub-pressure loss ΔP2 is larger, is compensated by the fuel from the feed pump 11 at a lower speed, causing the fuel pressure to increase moderately from the changing point A2 as indicated by a broken line in 8th is specified. Accordingly, it is possible to estimate the magnitude of the sub-pressure loss ΔP2 by comparing the hold fuel pressure Pb, which corresponds to the sub-fuel pressure P2 detected during the time period from the changing point A3 to the changing point A4, with a reference value Pa. According to the present embodiment, focusing on this fact, the aforesaid hold fuel pressure Pb is detected. If the difference between the hold fuel pressure Pb and the reference value Pa is greater than or equal to a threshold value TH3, it is determined that the sub pressure loss ΔP2 is in an abnormal state in which the sub pressure loss ΔP2 is greater than or equal to a predetermined value and a warning is generated for the user.

The processing described later in 9 is carried out specifically by the microcomputer. This processing in 9 is repeatedly executed at a predetermined time cycle during the operation of the internal combustion engine.

At step S50 in 9 it is first determined whether there is a request to open the supply valve 15. The determination is made, for example, in a similar manner to step S30 in FIG 5 carried out. If it is determined that there is a request for introduction, that is, if the supply valve 15 is in an open valve state, the aforesaid hold fuel pressure Pb is obtained at step S51. For example, the sub fuel pressure P2 at the time when a predetermined time period has elapsed from the issuance of the command to start energizing the supply valve 15 during a time period corresponding to the time period from the changing point A3 to the changing point A4 as the Hold fuel pressure Pb is considered, and the sub fuel pressure P2 at that time is acquired.

If the timing during which energization-on is instructed, that is, the timing during which the valve opening is instructed, is shorter than the aforesaid predetermined timing, it is not possible to obtain the holding fuel pressure Pb. In this case, the processing at and after step S51 cannot be executed and the processing in 9 will be temporarily terminated.

In step S52, it is determined whether the difference between the reference value Pa of the hold fuel pressure and the hold fuel pressure Pb obtained in step S51 is greater than or equal to the threshold value TH3. The reference value Pa may be set based on the sub fuel pressure P2 just before the valve opens. The sub fuel pressure P2 can be acquired at the time of outputting the energization-on command to the supply valve 15, for example. Further, the reference value Pa can be calculated by multiplying this sub fuel pressure P2 by a predetermined factor or by reducing this sub fuel pressure P2 by a predetermined constant.

If it is determined that the aforesaid difference is greater than or equal to the threshold value TH3, it is judged at step S53 that the sub-filter 32 is in an abnormal state in which the degree of clogging of the sub-filter 32 due to the captured therein Foreign matter has reached a limit, and a sub pressure loss anomaly flag is set to On. At step S54, a warning lamp is lit or a warning sound is emitted to prompt the user to replace the sub-filter 32.

If the sub-filter 32 has been replaced with a new one, it is determined at step S52 that the aforesaid difference is smaller than the threshold value TH3. In this case, the sub pressure loss anomaly flag is set to off at step S55, which prevents the warning from being generated for the user. Furthermore, the processing in 9 ends without performing the processing at steps S51 to S55 when it is determined at step S50 that there is a request for adding.

As described above, according to the present embodiment, focusing on the fact that the pulsation at the sub fuel pressure P2 caused by opening and closing operations of the supply valve 15 has a strong correlation with the sub pressure loss ΔP2, a sub a pressure loss determination unit adapted to determine whether the sub pressure loss is in an abnormal state in which the sub pressure loss ΔP2 is greater than or equal to a predetermined value based on the fuel pressure waveform. This sub pressure loss determination unit is provided by the microcomputer which executes the processing at step S52 in FIG 9 executes This enables determination of the presence or absence of abnormalities in the sub pressure loss with higher accuracy. This makes it possible to prompt the user to replace the sub-filter 52 with higher accuracy before the occurrence of a shortage in the pressure of the reducing agent supplied to the sub-filter 32 due to clogging of the sub-filter 32 .

As described above, the fuel pressure during the predetermined period of time from the issuance of an energization-on command to the supply valve 15 to the issuance of an energization-off command to the supply valve 15 from the changing point A3 to the Changing point A4 is kept at a constant value (the hold fuel pressure Pb) as in FIG 8th is shown. Further, the sub fuel pressure P2, which has decreased since the valve was opened, reverses to increase from the changing point A2. At this time, the increase in the sub fuel pressure P2 is moderate while the sub pressure loss ΔP2 becomes larger. Therefore the Sub fuel pressure P2 is more restricted from immediately increasing to the normal hold fuel pressure value (reference value Pa) while the sub pressure loss ΔP2 is larger. In view of this fact, according to the present embodiment, the sub pressure loss determination unit makes the determination based on the sub fuel pressure P2 during the valve opening timing of the supply valve 15 and at the time when a predetermined timing has elapsed since the start of opening of the supply valve 15 , out of. Therefore, the presence or absence of an abnormality in the sub pressure loss is determined based on whether the hold fuel pressure Pb immediately increased to the normal value. This can easily realize the determination of an abnormality in the sub-pressure loss based on the pulsation.

(Fifth embodiment)

In the present embodiment, the flowchart is in FIG 9 according to the aforementioned fourth embodiment to an in 10 shown flowchart remodeled. Furthermore, in the present embodiment, the same control as the control in FIG 2 and 3 carried out according to the aforesaid first embodiment.

At step S510 in 10 first, it is determined whether a request for diagnosing whether the sub pressure loss ΔP2 is in a normal state has been made. For example, in a manner similar to step S310 in 6 a request for performing a diagnosis is made based on the cumulative vehicle running distance or the cumulative feed amount.

If it is determined that a request for diagnosis has been made, it is determined at step S50 whether there is a request to open the supply valve 15. The determination is made, for example, in a similar manner to step S30 in FIG 5 carried out. If it is determined that there is a request for bringing in, that is, if the supply valve 15 is in an open valve state, the process proceeds to step S520. At step S520, the target delivery amount Qtrg of the delivery valve 15 is forcibly set to a value greater than or equal to a predetermined value set in advance (a delivery amount for the determination), regardless of the step S22 in FIG 3 set target feed amount, changed. In other words, the valve opening timing of the supply valve 15, that is, the energization-on timing, is controlled to achieve a supply amount which is greater than or equal to the supply amount for the determination, regardless of the value of the target supply amount Qtrg at the supply valve 15.

After the processing at step S520, it proceeds similarly to steps S51 to S55 in FIG 10 the sub-pressure loss ΔP2 at the time when a predetermined period of time has elapsed from the issuance of the command to start energization to the supply valve 15 when the hold fuel pressure Pb is acquired. Further, if the difference between the obtained hold fuel pressure Pb and the reference value Pa is greater than or equal to the threshold value TH3, an abnormality is determined and a warning is generated for the user.

In this case, there is a longer time phase from the change point A3 to the change point A4, as in FIG 8th 1, before while the valve opening timing phase is longer, which can reduce the concern of obtaining the sub fuel pressure P2 at a time different from that timing. In the present embodiment, in view of this fact, a cleaning delivery control unit and a destination delivery control unit are provided. The purification supply control unit is adapted to calculate the target supply amount Qtrg of the reducing agent supplied through the supply valve 15 based on the amount of NOx discharged. The determination delivery control unit is adapted to forcibly set the valve opening timing to a predetermined timing or longer regardless of the target delivery amount Qtrg. Therefore, according to the present embodiment, when a request for diagnosis is made, the timing is forcibly lengthened from the changing point A3 to the changing point A4. This can reduce the aforementioned risk.

Further, the cleaning supply control unit is provided by the microcomputer which executes the processing at step S23 in FIG 3 executes The determination feed control unit is provided by the microcomputer which executes the processing at step S520 in FIG 10 executes

(Further embodiments)

Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the aforementioned embodiments and can be implemented by making various changes to the embodiments as explained later. It is possible sections in the embodiments which are specifically specified to be able to be combined with each other, and it is also possible to partially combine the embodiments with each other, particularly provided that such combinations do not create any obstacle even if such combinations are not specified.

In the aforementioned fourth embodiment, the diagnosis is performed based on the value of the hold fuel pressure Pb occurring at the pulsation to detect an abnormality in the sub fuel pressure based on the pulsation at the sub fuel pressure P2 caused by opening and Closing operations of the supply valve 15 is caused to diagnose. On the other hand, focusing on the fact that the rate (increase slope B1) of increase in fuel pressure during the time phase from the changing point A2 to the changing point A3 as shown in FIG 8th 1 is slowed down while the sub-pressure loss ΔP2 is larger, it is also possible to make a diagnosis based on the increasing tendency B 1 . Further, focusing on the fact that the speed (decrease slope B2) of the decrease in fuel pressure in the time phase from the changing point A1 to the changing point A2 as shown in FIG 8th shown is increased while the sub-pressure loss ΔP2 is larger, it is also possible to perform a diagnosis based on the decreasing tendency B2.

When performing the pressure loss diagnostics in the 5 , 7 and 10 it is also possible to perform the pressure loss diagnosis by being initiated by a request for performing the diagnosis made based on the cumulative vehicle running distance or the cumulative feed amount, in a similar manner to step S310 in FIG 6 .

In the 1 illustrated feed pump 11 is arranged in the fuel tank 10; however, the feed pump 11 can also be arranged outside of the fuel tank 10 .

The target delivery amount via the delivery pump 11 is calculated based on the target suction amount at step S13 2 calculated. However, when a request for adding the reducing agent has been made, it is also possible to calculate the target delivery amount by adding the amount of the reducing agent to the target intake amount.

Although the sub-pressure loss abnormality determination is performed in addition to the main pressure-loss abnormality determination in the aforementioned first and second embodiments, it is also possible to omit the sub-pressure loss abnormality determination. Although the main pressure loss abnormality determination is performed in addition to the sub pressure loss abnormality determination in the aforementioned third to fifth embodiments, it is also possible to omit the main pressure loss abnormality determination. Further, it is possible to perform the main pressure loss abnormality determination according to the first and second embodiments and the sub pressure loss abnormality determination according to the third to fifth embodiments by combining them.

The functions provided by the ECU 50 (the control device) may be provided by software recorded in a substantive storage medium and a computer for executing the same, or only by software, hardware, or combinations of these. For example, when the control device is provided by a circuit constituting hardware, the control device may be provided by a digital circuit including a plurality of logic circuits, or by an analog circuit.

Claims (8)

A fuel filter device connected to a fuel supply system having a supply pump (12) for discharging a high-pressure fuel for use in combustion in an internal combustion engine, a feed pump (11) for discharging a low-pressure fuel having a lower pressure than the high-pressure fuel toward the feed pump, and a feed valve ( 15) adapted for introducing a part of the low-pressure fuel as a reducing agent into an air outlet path (16a) in the internal combustion engine, the fuel filter device comprising: a main filter (31) arranged in a main path (21a) as a fuel path from the feed pump to the supply pump is arranged and adapted to receive a foreign matter contained in the low-pressure fuel; a sub-filter (32) which is arranged in a sub-path (22a) branching from the main path at an upstream portion of the main filter for supplying the low-pressure fuel toward the supply valve and adapted to take in a foreign substance which is in the low-pressure fuel is included; a main fuel pressure sensor (41) for detecting a main fuel pressure corresponding to a fuel pressure downstream of the main filter in the main path; a sub fuel pressure sensor (42) for detecting a sub fuel pressure corresponding to a fuel pressure downstream of the sub filter in the sub path; and a main pressure loss determination unit (S36) adapted to determine whether the main filter is in a abnormal condition in which the main filter has a pressure drop greater than or equal to a threshold. Fuel filter device after claim 1 , further comprising a transient time preventing unit (S31) adapted to prevent the determination of whether the main filter is in an abnormal state in a transient time from when the supply valve starts to close until a predetermined time elapses within the valve closing timing . Fuel filter device after claim 1 or 2 , further comprising a low flow rate time prohibiting unit (S34) adapted to prohibit determination of whether the main filter is in an abnormal state within the valve closing timing phase when a flow rate of the low pressure fuel is smaller than a predetermined value. Fuel filter device after claim 1 or 2 , further comprising: a feed pump control unit (S 13) adapted to calculate a target flow rate of the low pressure fuel from the feed pump based on an amount of the high-pressure fuel to be supplied to the internal combustion engine, and so adjusted is that controls an operation of the feed pump based on the target flow rate; and a determination pump control unit (S320) adapted to forcibly set the flow rate of the low-pressure fuel to a predetermined value or greater regardless of the target flow rate. A fuel filter device connected to a fuel supply system having a supply pump (12) for discharging a high-pressure fuel for use in combustion in an internal combustion engine, a feed pump (11) for discharging a low-pressure fuel having a lower pressure than the high-pressure fuel toward the feed pump, and a feed valve ( 15) adapted for introducing a part of the low-pressure fuel as a reducing agent into an air outlet path (16a) in the internal combustion engine, the fuel filter device comprising: a main filter (31) which is arranged in a main path (21a) as a fuel path from the feed pump to the supply pump and adapted to capture a foreign substance contained in the low-pressure fuel; a sub-filter (32) which is arranged in a sub-path (22a) branching from the main path at an upstream portion of the main filter for supplying the low-pressure fuel toward the supply valve and adapted to take in a foreign substance which is in the low-pressure fuel is included; a main fuel pressure sensor (41) for detecting a main fuel pressure corresponding to a fuel pressure downstream of the main filter in the main path; a sub fuel pressure sensor (42) for detecting a sub fuel pressure corresponding to a fuel pressure downstream of the sub filter in the sub path; and a sub pressure loss determining unit (S45) adapted to determine whether the sub filter is in an abnormal state based on the main fuel pressure and the sub fuel pressure detected during a valve opening timing of the supply valve located at which the sub-filter has a pressure drop that is greater than or equal to a threshold. A fuel filter device connected to a fuel supply system having a supply pump (12) for discharging a high-pressure fuel for use in combustion in an internal combustion engine, a feed pump (11) for discharging a low-pressure fuel having a lower pressure than the high-pressure fuel toward the feed pump, and a feed valve ( 15) adapted for introducing a part of the low-pressure fuel as a reducing agent into an air outlet path (16a) in the internal combustion engine, the fuel filter device comprising: a main filter (31) arranged in a main path (21a) as a fuel path from the feed pump to the supply pump is arranged and adapted to receive a foreign matter contained in the low-pressure fuel; a sub-filter (32) which is arranged in a sub-path (22a) branching from the main path at an upstream portion of the main filter for supplying the low-pressure fuel toward the supply valve and adapted to take in a foreign substance which is in the low-pressure fuel is included; a sub fuel pressure sensor (42) for sensing a sub fuel pressure corresponding to a fuel pressure downstream of the sub filter in the sub path; and a sub pressure loss determining unit (S52) adapted to determine whether the sub filter is in an abnormal state based on a change in the sub fuel pressure caused by an opening and closing operation of the supply valve State is in which the sub-filter has a pressure loss that is greater than or equal to a predetermined value. Fuel filter device after claim 6 wherein the sub-pressure loss determination unit is adapted to determine whether the sub-filter is in an abnormal state based on the sub-fuel pressure during a valve-opening timing of the supply valve and at a point in time when a predetermined timing starts has elapsed from a start of opening of the supply valve. Fuel filter device after claim 6 or 7 , further comprising: a purification supply control unit (S23) adapted to calculate a target amount of the reducing agent to be supplied through the supply valve based on an amount of NOx discharged from the internal combustion engine, and adapted to that it controls a valve opening timing phase of the supply valve based on the target amount of the reducing agent to be supplied; and a determination supply control unit (S520) adapted to forcibly set the valve opening timing to a preset timing or longer regardless of the target amount of reducing agent to be supplied.

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