JP3339326B2 - Fuel supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device, and more particularly, to a fuel supply system in which fuel is pressure-fed to a common rail (accumulation chamber) and stored in a high pressure state, and the fuel is supplied from the common rail via an injector (fuel injection valve). The present invention relates to a fuel supply device that injects high-pressure fuel into each cylinder of an internal combustion engine.

[0002]

2. Description of the Related Art In diesel engines, it is necessary to achieve precise control of high-pressure fuel. Conventionally, as a fuel supply device for a diesel engine, a device including a fuel injection pump and a nozzle has been generally used.
Common rail fuel injection systems have been developed. This common-rail fuel injection system stores high-pressure fuel generated by a high-pressure pump in a common rail, and injects high-pressure fuel from the common rail to each cylinder of the engine by opening and closing a solenoid valve. The pressure is always controlled to an optimum value by the pressure sensor and the discharge amount control mechanism of the pump.

[0003] As an example of such a fuel supply device, Japanese Patent Laid-Open Publication No. 4-109052 discloses a fuel supply device for controlling a fuel pressure in a pressure accumulator to a predetermined pressure when a fuel supply command amount is larger than a predetermined reference value. A fuel supply device for determining leakage is disclosed.

[0004]

However, in the above prior art, the fuel supply command amount is calculated for each fuel injection, and in fact, the injection amount of the fuel injection valve provided for each cylinder is abnormal. The amount of change in the fuel supply command amount due to
A fuel leak is determined based on a value that includes a change in the fuel supply command amount due to a decrease in the pumping capacity of the high-pressure pump and a change in the fuel supply command amount due to leakage from the fuel piping system. Therefore, it is impossible to identify the cause of the change in the fuel supply command amount, whether it is actually due to fuel leakage in the piping system, due to abnormal fuel injection amount, or due to reduced pumping capacity of the pump. There's a problem.

In view of such circumstances, it is an object of the present invention to provide a fuel system in which fuel is pumped to a pressure accumulator and stored in a high pressure state, and high pressure fuel is injected from the pressure accumulator to each cylinder of the internal combustion engine via a fuel injection valve. An object of the present invention is to perform an abnormality determination that allows identification of an abnormal part in a supply device.

[0006]

To achieve the above object, according to a first aspect of the present invention, fuel is pumped to a pressure accumulating chamber by a high-pressure pump, and the fuel is supplied from the pressure accumulating chamber through a fuel injection valve. What is claimed is: 1. A fuel supply device for injecting fuel into a cylinder of an internal combustion engine, comprising: a pressure detecting means for detecting a pressure of fuel in the accumulator; and controlling a pressure of fuel in the accumulator to a desired pressure according to an engine operating state. For this purpose, a fuel pumping command amount calculating means for calculating a fuel pumping command amount for pumping fuel to the pressure accumulating chamber based on a detection value of the pressure detecting means, and two timings not including a fuel injection period are provided. A pressure deviation calculation that detects the pressure of the fuel in the accumulator by the pressure detection means at two set pressure detection timings and calculates a deviation between the pressures at the two pressure detection timings based on the detected pressures. And an abnormality determining means for determining an abnormal part of the fuel supply device based on the pressure deviation calculated by the pressure deviation calculating means and the fuel pumping command amount calculated by the fuel pumping command amount calculating means. A fuel supply device is provided.

According to a second aspect of the present invention, in the fuel supply device according to the first aspect of the present invention, the two pressure detection timings do not further include a fuel pumping period. The abnormality determining means determines that fuel is leaking from the fuel pipe when the pressure deviation calculated by the pressure deviation calculating means is larger than a pressure deviation reference value serving as a reference for determining abnormality.

According to a third aspect of the present invention, in the fuel supply device according to the first aspect of the present invention, the two pressure detection timings do not further include a fuel pumping period. The abnormality determining means is configured such that the pressure deviation calculated by the pressure deviation calculating means does not exceed a pressure deviation reference value serving as a criterion for determining abnormality, and the fuel pumping command amount calculated by the fuel pumping command amount calculating means is It is determined that the high-pressure pump is abnormal when it is larger than the command amount reference value serving as a criterion for determining abnormality.

According to a fourth aspect of the present invention, in the fuel supply device according to the first aspect of the present invention, the two pressure detection timings include a fuel pumping period in between, and the abnormality determination is performed. The means, when the pressure deviation calculated by the pressure deviation calculating means is smaller than a pressure deviation reference value determined according to the fuel pumping command amount calculated by the fuel pumping command amount calculating means, the fuel from the fuel pipe also It is determined that it is.

[0010] According to a fifth aspect of the present invention, in the fuel supply device according to the first aspect of the present invention, at the start timing and the stop timing of the fuel injection, the pressure detecting means detects the pressure in the accumulator chamber. Detecting a fuel pressure, calculating a pressure decrease amount in a fuel injection period based on the detected pressure, and determining a fuel injection valve abnormality of a specific cylinder based on the pressure decrease amount. Have.

According to a sixth aspect of the present invention, in the fuel supply device according to the second or third aspect of the present invention, the two pressure detection timings are set during fuel cut.

According to a seventh aspect of the present invention, in the fuel supply device according to the second or third aspect of the present invention, the two pressure detection timings are set immediately after fuel pressure feeding and immediately before fuel injection. Each is set.

In the fuel supply device according to the first aspect of the present invention, which is configured as described above, the abnormal portion can be reliably determined based on the fuel pumping command amount and the pressure deviation. Therefore, since the abnormal part can be accurately specified, it is possible to perform an optimal countermeasure against the abnormal part.

In the fuel supply device according to the second aspect of the present invention, when the pressure deviation is abnormal at two timings that are not included in the fuel injection period and the fuel pumping period, the fuel from the fuel pipe is also supplied. It is determined that this is the case.

In the fuel supply device according to the third aspect of the present invention, since the pressure deviation is normal at two timings not included in the fuel injection period and the fuel pumping period, the fuel leaks from the fuel pipe. When it is determined that the fuel supply command amount is abnormal, it is determined that the high-pressure pump is abnormal, such as a decrease in pumping capacity, even though it is recognized that the fuel supply command amount is abnormal.

In the fuel supply device according to the fourth aspect of the present invention, when the pressure is not increased according to the fuel pumping command amount even though the fuel is pumped, the fuel from the fuel pipe is It is determined that there is a leak.

In the fuel supply device according to the fifth aspect of the present invention, when a normal decrease in the pressure of the fuel in the accumulator is not recognized even though the fuel has been injected, the cylinder related to the injection is provided. Is determined to be abnormal.

In the fuel supply device according to the sixth aspect of the present invention, two timings that are not included in the fuel injection period and the fuel pumping period are set during the fuel cut. This is easily performed, and the detection accuracy is improved.

In the fuel supply apparatus according to the seventh aspect of the present invention, two timings not included in the fuel injection period and the fuel pumping period are set immediately after the fuel pumping and immediately before the fuel injection, respectively. The accuracy is improved.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing a configuration of a fuel supply device for a diesel engine according to one embodiment of the present invention, and FIG. 2 is a time chart for explaining a control operation of the fuel supply device. As shown in FIG. 1, the fuel supply device includes a two-cylinder high-pressure pump 1.
The high-pressure pump 1 is provided with a drive shaft 2.
When the crankshaft 4 makes two rotations, the drive shaft 2 makes one rotation. Further, triangular cams 5 and 6 are fixed to the drive shaft 2. Further, cylinders 7 and 8 are provided in the high-pressure pump 1, and pistons 9 and 10 that slide on the cam surfaces of the cams 5 and 6 are arranged in the cylinders 7 and 8. Solenoid valves 15 and 16 for controlling the amount of feed are arranged above the cylinders 7 and 8.
Reference numerals 5 and 16 are used to open and close a fuel supply passage from the low-pressure pump 13. The pressurizing chamber 1 in the cylinders 7 and 8
The fuel supply pipes 1 and 12 are connected to a pressure accumulation chamber common to the cylinders, that is, a so-called common rail 19 via fuel supply pipes 17 and 18.

When the cams 5 and 6 rotate, the pistons 9 and 10 are opened with the pressure feed amount controlling solenoid valves 15 and 16 open.
Is moved, the pressurizing chambers 11 in the cylinders 7 and 8
The fuel in the tank 14 is sucked into the tank 12 through the low-pressure pump 13. When the pistons 9 and 10 move upward in a state where the electromagnetic valves 15 and 16 for controlling the pressure feed amount are opened, the pressurizing chamber 1 is moved.
The fuel in the pressurizing chambers 11 and 12 is returned to the low-pressure pump 13 when the solenoid valves 15 and 16 for controlling the pumping amount are closed during the upward movement of the pistons 9 and 10. Fuel is supplied to the common rail 19 via fuel supply pipes 17 and 18.
To be pumped. That is, by controlling the valve closing timing (TF in FIG. 2) of the solenoid valves 15 and 16 during the upward movement of the piston, the high-pressure pump 1
The fuel pumping amount to 9 (shaded area in FIG. 2) can be adjusted. The electromagnetic valves 15 and 16 for controlling the feed amount are opened at the top dead center of the cam lift (θ _{0 in} FIG. 2).

A check valve 20 is provided at the pump-side end of the fuel supply pipe 17, and a check valve 21 is provided at the common-rail-side end. Similarly, a check valve 22 is provided at the pump-side end of the fuel supply pipe 18, and a check valve 23 is provided at the common rail-side end. These check valves 20, 21, 22 and 23 are connected to the high-pressure pump 1
This allows the fuel to be pumped from the side to the common rail 19 and restricts the return of fuel from the common rail 19 to the high-pressure pump 1.

The common rail 19 is connected to each injector (fuel injection valve) 25 of each cylinder of the diesel engine 3 via each branch pipe 24. A flow limiter 26 is provided at an end of the branch pipe 24 on the common rail side. The flow limiter 26 permits the supply of fuel to the injector 25 in a certain amount or less, and regulates the fuel supply to the injector 25 in a certain amount or more. That is, the flow limiter 26 limits the fuel supply to the injector 25 when the injector 25 is damaged for some reason.

The injector 25 has a three-way solenoid valve 3
By controlling the three-way solenoid valve 31, high-pressure fuel stored in the common rail 19 can be injected from the injector 25 to each cylinder. In addition, a part of the fuel is not injected from the injector 25 and the fuel return pipe 33 is supplied from the three-way solenoid valve 31.
Through the fuel tank 14.

Electronic control unit (hereinafter referred to as ECU)
27 is determined according to the engine state determined from these signals by obtaining information on the engine speed, the crank angle position and the accelerator opening from the crank angle sensor 28, the cylinder discriminating sensor 29 and the accelerator opening sensor 30. A control signal is output to the three-way solenoid valve 31 so that the optimum fuel injection timing and fuel injection amount are obtained. As shown in FIG. 2, the crank angle sensor 28 outputs a one-pulse signal every predetermined crank angle, and the cylinder discrimination sensor 29 outputs a one-pulse signal every one rotation of the drive shaft 2.

Further, the common rail 19 has a common rail pressure sensor 32 for detecting the pressure of fuel in the common rail.
The ECU 27 controls the pumping amount of the high-pressure pump 1 so that the common rail pressure by the sensor 32 becomes an optimum value set according to the accelerator opening and the number of revolutions.

When the diesel engine 3 starts, the cams 5 and 6 of the high-pressure pump 1 rotate, and with this rotation, the pistons 9 and 10 reciprocate to supply fuel from the low-pressure pump 13 to the high-pressure pump 1. The high-pressure fuel is fed to the common rail 19 through the fuel supply pipes 17 and 18, and the fuel is stored in the common rail 19 in a high-pressure state.

That is, when the ECU 27 receives a pulse signal from the crank angle sensor 28, the ECU 27 starts processing.
First, the common rail pressure by the common rail pressure sensor 32, the accelerator opening by the accelerator opening sensor 30, and the engine speed by the crank angle sensor 28 are taken. Then, the ECU 27 sets the high-pressure pump 1 based on the predetermined crank angle θa so that the common rail pressure becomes an optimum value set according to the accelerator opening and the number of revolutions.
Is calculated (see FIG. 2). Next, the ECU 27 closes the pumping amount control solenoid valves 15 and 16 when the fuel pumping start timing TF shown in FIG. 2 is reached, so that a desired amount of high-pressure fuel is transferred from the high-pressure pump 1 to the common rail 19. Pump.

The ECU 27 controls the opening and closing of the three-way solenoid valve 31 of the injector 25 so as to inject a fuel amount corresponding to the operating state of the diesel engine 3 into the cylinder, and the fuel in the common rail 19 is supplied to each cylinder of the diesel engine 3. Spray.

Incidentally, if there is a pump abnormality such as fuel leakage from the fuel pipe, common rail, injector, etc., or a decrease in the pumping ability, the fuel pumping command amount becomes an abnormally large value that cannot be obtained under normal conditions. Therefore, it is possible to detect an abnormality of the fuel injection system by monitoring the fuel pumping command amount.

FIG. 3 is a flowchart showing a procedure of a processing routine for calculating a fuel pumping command amount, that is, a fuel pumping start timing TF (see FIG. 2) and judging an abnormality of the calculated TF. This routine is configured to be executed at every predetermined crank angle at 120 ° CA (crank angle) intervals. First, in step 102, the current accelerator opening θA and engine speed NE are detected based on the outputs of the accelerator opening sensor 30 and the crank angle sensor 28. Next, at step 104, the target common rail pressure PCt is calculated according to the detected accelerator opening θA and the engine speed NE. In addition,
For this calculation, a predetermined map is stored in the ECU in advance, and an interpolation calculation based on this map is executed. Next, at step 106, the fuel pumping start timing TF is determined according to the accelerator opening θA and the engine speed NE.
Failure determination reference value TF _MIN is calculated for. That is, T
F _{MI N,} the fuel pumping start time TF is a value such not be assumed that earlier than this in normal. In order to calculate TF _MIN, a predetermined map is set in advance in EC.
U, and an interpolation calculation based on this map is performed.

Next, at step 108, based on the output of the common rail pressure sensor 32, the actual common rail pressure PC
Is detected. Next, a difference ΔPC between the target common rail pressure PCt and the actual common rail pressure PC is calculated. Next, at step 112, the fuel pumping command amount according to the calculated ΔPC, that is, the fuel pumping start timing TF is calculated. For this calculation, a predetermined map is set in advance.
It is stored in the CU, and an interpolation calculation based on this map is executed. Next, at step 114, it is determined whether or not the calculated fuel pumping start time TF is smaller than the abnormality determination reference value TF _MIN . If TF <TF _MIN, it is recognized that there is some abnormality in the fuel supply system, so the routine proceeds to step 116, where the system abnormality flag FS is set to 1.

By the way, in a state where fuel injection is stopped, such as when the vehicle is in a decelerating state or an engine braking state,
There is no need to pump fuel to the common rail 19. In such a state where neither fuel injection nor fuel pumping is performed, the common rail pressure PC is normal and the curve C _{0 in} FIG.
At a pressure drop rate as shown in FIG.
However, the fuel supply pipe 17, a common rail 19, if there is a fuel leakage from such an injector 25, as indicated by curve C ₂ in FIG. 4, the pressure drop rate increases.
Therefore, setting the determination reference value of the rate of pressure drop as indicated by the curve C ₁ in FIG. 4, if the detection value of the pressure drop rate exceeds the determination reference value, it is determined that fuel leakage it can.

FIG. 5 is a flowchart showing a processing procedure of a fuel cut (F / C) abnormality determination routine executed based on the above knowledge. This routine is started as a service routine for a timer interrupt generated at a predetermined time period. First, in step 202, it is determined whether or not a fuel cut is being performed.
This abnormality determination is abandoned, and the routine ends. On the other hand, if the fuel is being cut, the process proceeds to step 204, in which the fuel supply from the high-pressure pump 1 to the common rail 19 is stopped.

Next, at step 206, a value TIM of a predetermined timer for counting a value corresponding to time is read, and
Stores it as T _1, detects the common rail pressure PC based on an output of the common rail pressure sensor 32, and stores it as P _1. Then, step 20
In step 8, it is determined whether or not a predetermined time has elapsed since the execution of step 206.
The process proceeds to step 212 if the time has elapsed. In step 210, it is determined whether or not the fuel cut is continued. If the fuel cut is continued, the process loops back to step 208, while if the fuel cut is not stopped, this routine ends.

[0037] In step 212 is executed after a lapse of a predetermined time from the time of the step 206 executed again reads the value TIM of the timers, stores it as T _2, the common rail pressure based on the output of the common rail pressure sensor 32 detecting a PC, and stores it as P _2. Then, in step _{214, Vd ← (P 1 -P} 2) / a (T ₂ -T ₁₎ becomes operational, determining the rate of pressure drop Vd. Then
In step 216, (the slope of the curve C ₁ in FIG. 4) calculated pressure drop determination speed Vd is predetermined reference value R ₀ determines smaller or not. If Vd <R ₀ , it is regarded as normal and this routine ends. On the other hand, Vd ≧ R ₀
In step 218, it is determined that there is a fuel leak.
Then, the fuel leakage flag FL is set to 1 and the routine ends.

FIG. 6 is a diagram showing an output signal waveform of the common rail pressure sensor 32. As shown in the drawing, the pressure PC of the fuel in the common rail increases during a period in which fuel is being pumped from the high-pressure pump 1 and decreases during a period in which fuel is injected from the injector 25. Here, the common rail pressure immediately after fuel pumping is P
C1, the common rail pressure immediately before fuel injection is PC2, and the common rail pressure immediately after fuel injection is PC3.

The amount of pressure drop from PC1 to PC2 is in a period during which neither fuel pumping nor fuel injection is performed, so that it takes a small value under normal conditions, but a large value if there is fuel leakage. Become. Therefore, it is possible to determine whether or not there is fuel leakage by monitoring the amount of pressure drop from PC1 to PC2. Also, the pressure increase amount from PC3 to PC1 should show a value corresponding to the fuel pumping command amount in a normal state. In other words, when the pressure increase according to the fuel pumping command amount is not recognized, it can be determined that there is fuel leakage. Further, when considering the pressure drop amount from PC2 to PC3, when a normal pressure drop is not recognized even though fuel is injected, that is, the pressure drop amount fluctuates at the time of injection of a specific cylinder. Sometimes, it can be determined that there is an abnormality in the injector 25 related to the injection. The abnormality determination processing created based on the above knowledge will be described below.

FIG. 7 is a flowchart showing the processing procedure of the abnormality determination routine immediately after fuel pressure feeding. This routine is
It is configured to be called from a main routine (not shown) when the fuel pumping is completed. First, in step 302, the current common rail pressure PC is detected based on the output of the common rail pressure sensor 32, and is detected by the PC.
Stored as 1. Next, in step 304, from the PC1, by reducing the common rail pressure PC3 after already sought fuel injection in the abnormality determining routine immediately after the fuel injection to be described later, to calculate the pressure increase amount DP _13.

[0041] Then, in step 306, it calculates a criterion value R ₁ according to the fuel pumping start time TF. In addition,
For this calculation, a predetermined map is stored in the ECU in advance, and an interpolation calculation based on this map is executed. Then, in step 308, the pressure increase amount DP ₁₃ calculated determines whether the determination reference value R ₁ is smaller than. If DP ₁₃ ≧ R ₁ , this routine is terminated, assuming that the pressure increase according to the fuel pumping command amount has been normal. On the other hand, when DP ₁₃ <R ₁ , it is determined that there is a fuel leak, and the routine proceeds to step 310, where the fuel leak flag FL is set to 1, and this routine ends.

FIG. 8 is a flowchart showing the processing procedure of the abnormality determination routine immediately before fuel injection. This routine is
It is configured to be called from a main routine (not shown) immediately before the fuel is injected. First, in step 402, the current common rail pressure PC is detected based on the output of the common rail pressure sensor 32, and is detected by the PC.
Stored as 2. Next, in step 404, by subtracting the PC1 from PC2 that has already been determined by the fuel pumping immediately after the abnormality determination routine described above, to calculate the pressure drop amount DP _12.

[0043] Then, in step 406, the pressure drop amount DP ₁₂ calculated determines whether a predetermined larger criterion value R _2. When DP ₁₂ ≦ R ₂ , this routine is terminated because no abnormal pressure drop is recognized. On the other hand, when DP ₁₂ > R ₂ , it is determined that there is a fuel leak, and the routine proceeds to step 408, where the fuel leak flag FL is set to 1, and this routine ends.

FIG. 9 is a flowchart showing the processing procedure of the abnormality determination routine immediately after fuel injection. This routine is
It is configured to be called from a main routine (not shown) immediately after the fuel is injected. First, in step 502, the current common rail pressure PC is detected based on the output of the common rail pressure sensor 32, and is detected by the PC.
3 is stored. Next, in step 504, by subtracting the PC2 from PC3 that has already been determined by the fuel injection immediately before the abnormality determination routine described above, to calculate the pressure drop amount DP _23.

[0045] Then, in step 506, the calculated pressure reduction amount DP ₂₃ is within a predetermined range (R ₃ <DP ₂₃ <
R ₄ ). If it is within this range, it is considered that the fuel injection amount was normal, and this routine ends. On the other hand, when the fuel injection amount is not within the range, it is considered that the fuel injection amount is abnormal, and the routine proceeds to step 508, and the cylinder number j (j = 1, 2,..., 6) related to the injection
Then, the routine proceeds to step 510, where the injector operation failure flag FI (j) of the j-th cylinder is set to 1, and this routine ends. The detection of the malfunction of the injector in the specific cylinder may be performed based on a change in the rotation speed, a change in the pumping start timing, or the like. Also,
In the separately executed fuel injection control, the injection amount can be corrected based on the injection amount variation for each cylinder detected as described above.

FIG. 10 is a flowchart showing the processing procedure of the abnormality countermeasure routine. This routine is configured to be executed at a predetermined time period. First, in step 602, it is determined whether or not the injector malfunction flag FI (j) of any one of the cylinders is 1. If FI (j) = 1 for any of the cylinders, the flow proceeds to step 612, and When FI (j) = 0 for the cylinder No., the process proceeds to step 604.

In step 604, it is determined whether or not FL = 1 holds, that is, whether or not fuel leakage is detected. If fuel leakage is detected, step 612 is executed.
On the other hand, if no fuel leak is detected, the process proceeds to step 606. In step 606, the TF of FIG.
In the calculation and TF abnormality determination routine, it is determined whether or not the system abnormality flag FS has been set to 1. When FS = 0, this routine ends. On the other hand, when FS = 1, that is, there is some abnormality in the fuel supply device. If it is recognized, the process proceeds to step 608. Step 608
Then, although it is recognized that there is no fuel leakage, since a system abnormality is detected, it is determined that there is an abnormality of the high-pressure pump such as a decrease in pumping ability, the pump abnormality flag FP is set to 1, and the step Proceed to 610.

In step 610 executed when it is determined that the pump is abnormal, since it is not a serious failure enough to stop the vehicle, only a measure for issuing a warning by some abnormality notification means is provided. On the other hand, in step 612, which is executed when a fuel leak or a malfunction of the injector is detected, a measure for stopping the vehicle is performed so that an unexpected situation does not occur.

Although the embodiments of the present invention have been described above, the present invention is of course not limited to these embodiments.

[0050]

As described above, according to the present invention,
In a fuel supply device that injects high-pressure fuel into each cylinder of an internal combustion engine through a fuel injection valve from a pressure accumulation chamber by sending fuel to a pressure accumulation chamber and storing the fuel under a high pressure state, an abnormality determination that can identify an abnormal portion is performed. It can be implemented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a fuel supply device for a diesel engine according to an embodiment of the present invention.

FIG. 2 is a time chart for explaining a control operation of the fuel supply device.

FIG. 3 is a flowchart illustrating a processing procedure of a TF (fuel pumping start time) calculation and TF abnormality determination routine.

FIG. 4 is a time chart showing a temporal change of a common rail pressure when fuel injection and pumping are stopped for a normal time (C ₀ ) and an abnormal time (C ₂ ).

FIG. 5 is a flowchart showing a processing procedure of a fuel cut (F / C) abnormality determination routine.

FIG. 6 is a diagram showing an output signal waveform of a common rail pressure sensor.

FIG. 7 is a flowchart illustrating a processing procedure of an abnormality determination routine immediately after fuel pressure feeding.

FIG. 8 is a flowchart illustrating a processing procedure of an abnormality determination routine immediately before fuel injection.

FIG. 9 is a flowchart illustrating a processing procedure of an abnormality determination routine immediately after fuel injection.

FIG. 10 is a flowchart illustrating a processing procedure of an abnormality countermeasure routine.

[Description of Signs] 1 ... High pressure pump (fuel supply pump) 2 ... Drive shaft 3 ... Diesel engine 4 ... Crank shaft 5,6 ... Triangular cam 7,8 ... Cylinder of high pressure pump 1 9,10 ... Piston 11,12 ... Pressurizing chamber 13 ... Low pressure pump 14 ... Fuel tank 15,16 ... Discharge (pressure feeding) amount control solenoid valve 17,18 ... Fuel supply pipe 19 ... Common rail (accumulation chamber) 20,21,22,23 ... Check valve Reference Signs List 24 branch pipe 25 injector (fuel injection valve) 26 flow limiter 27 electronic control unit (ECU) 28 crank angle sensor 29 cylinder identification sensor 30 accelerator opening sensor 31 three-way solenoid valve 32 common rail pressure sensor 33 ... fuel return pipe

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/00-45/00 395

Claims (7)

(57) [Claims] 1. A fuel supply device for pumping fuel to a pressure accumulator by a high-pressure pump and injecting fuel from the pressure accumulator into a cylinder of an internal combustion engine via a fuel injection valve. Pressure detecting means for detecting the pressure of the fuel in the accumulator, and controlling the pressure of the fuel in the accumulator to a desired pressure in accordance with the operating state of the engine. A fuel pumping command amount calculating means for calculating a fuel pumping command amount; and a fuel pressure in the accumulator chamber detected by the pressure detecting means at two pressure detection timings set as two timings not including a fuel injection period. A pressure deviation calculating means for calculating a pressure difference between the two pressure detection timings based on the detected pressure; a pressure deviation calculated by the pressure deviation calculating means; The fuel supply apparatus comprising an abnormality judging means for judging abnormalities in the fuel supply device based on the fuel delivery command value calculated by the command value calculating means. 2. The two pressure detection timings do not further include a fuel pumping period, and the abnormality determining means determines the pressure deviation calculated by the pressure deviation calculating means and the two pressures.
Predetermined pressure drop speed obtained from time interval of force detection time
The fuel supply device according to claim 1, wherein when it is larger than the determination reference value, it is determined that the fuel is leaking from the fuel pipe. 3. The two pressure detection timings do not further include a fuel pumping period, and the abnormality determining means determines that the pressure deviation calculated by the pressure deviation calculating means is a reference for determining abnormality. When the fuel pumping command amount calculated by the fuel pumping command amount calculating means does not exceed a reference value and is larger than a command amount reference value serving as a criterion for determining abnormality, it is determined that the high-pressure pump is abnormal. Claim 1
3. The fuel supply device according to item 1. 4. The two pressure detection timings include a fuel pumping period, and the abnormality determining unit calculates a pressure deviation calculated by the pressure deviation calculating unit by the fuel pumping command amount calculating unit. 2. The fuel supply device according to claim 1, wherein when the pressure difference is smaller than a pressure deviation reference value determined according to the fuel pumping command amount, it is determined that fuel is leaking from the fuel pipe. 5. The fuel pressure in the accumulator is detected by the pressure detecting means at a start time and a stop time of fuel injection, and a pressure drop amount during a fuel injection period is calculated based on the detected pressure. The fuel supply device according to claim 1, further comprising a fuel injection valve abnormality determination unit configured to determine abnormality of the fuel injection valve of the specific cylinder based on the pressure drop amount. 6. The fuel supply device according to claim 2, wherein the two pressure detection timings are set during a fuel cut. 7. The two pressure detection timings are set immediately after fuel pressure feeding and immediately before fuel injection, respectively.
Or the fuel supply device according to claim 3.