JP2009281184A - Fuel supply control device and fuel supply system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply control device determining abnormality of a relief valve, and a fuel supply system using the same. <P>SOLUTION: This fuel supply control device determines that the relief valve reducing feed pressure is closed and fixed (S404) when the rotational speed Np of a feed pump is higher than a predetermined rotational speed Np0 (S400:Yes) and a detected value Psout of feed pressure by a pressure sensor arranged between the feed pump and a fuel filter is higher than a value (Fp+Pt) with a tolerance Pt added to an estimate value Fp of feed pressure (S402:Yes). Also the fuel supply control device determines that the relief valve is opened and fixed (S408) when the rotational speed Np of the feed pump 32 is lower than the predetermined rotational speed Np0 (S400:No) and Psout<Fp-Pt (S406:Yes). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the present invention, fuel injected from a fuel injection valve to a cylinder of an internal combustion engine is supplied from a feed pump, a fuel filter is installed downstream of the feed pump, and the relief valve opens when the feed pressure of the feed pump exceeds a predetermined pressure. The present invention relates to a fuel supply control device used in a fuel supply system that reduces a feed pressure by valve.

  2. Description of the Related Art Conventionally, in a fuel supply system, foreign matter in fuel supplied from a feed pump is prevented from biting into, for example, a downstream high-pressure pump, a sliding portion of a fuel injection valve, or a valve portion of a fuel injection valve. In addition, it is known that foreign matters in the fuel are removed by a fuel filter installed on the downstream side of the feed pump (see, for example, Patent Document 1).

In such a fuel supply system, when the feed pressure of the feed pump exceeds a predetermined pressure, the relief valve opens to reduce the feed pressure of the feed pump, thereby adding an excessive fuel pressure to the fuel filter. Is prevented from being damaged.
JP 2006-207499 A

By the way, if a foreign object bites into the sliding part or the valve part of the relief valve, there is a possibility that the valve is stuck open so that the relief valve is always opened or the valve is stuck closed so that the relief valve is always closed.
If the relief valve is stuck open, the feed pressure of the feed pump does not rise sufficiently, so that the engine operating state may become unstable or the engine may start poorly when the engine speed is low.

  In addition, when the relief valve is fixedly closed, since the pressure cannot be reduced even if the feed pressure exceeds a predetermined pressure, an excessive fuel pressure is applied to the fuel filter and the fuel filter may be damaged. When the fuel filter is damaged, the foreign matter in the fuel flows out downstream without being removed. As a result, as a device installed on the downstream side of the fuel filter, for example, foreign matter may be caught in the sliding portion of the high-pressure pump or the fuel injection valve or the valve portion of the fuel injection valve.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a fuel supply control device that determines abnormality of a relief valve and a fuel supply system using the same.

  According to the first to sixth aspects of the present invention, the feed pressure detecting means adjusts the feed pressure of the feed pump based on the detection signal of the pressure sensor installed between the feed pump and the fuel filter downstream of the feed pump. The feed pressure estimation means estimates the feed pressure based on the operation state of the feed pump, and the abnormality judgment means detects the feed pressure detection value detected by the feed pressure detection means and the feed pressure estimated by the feed pressure estimation means. The abnormality of the relief valve of the feed pump is determined based on the estimated value.

  The relief valve opens when the feed pressure of the feed pump exceeds the specified pressure and reduces the feed pressure.If the relief valve does not open or close properly according to the feed pressure, it is detected based on the detection signal of the pressure sensor. Deviation occurs between the detected value of the feed pressure and the estimated value of the feed pressure estimated based on the operation state of the feed pump. Therefore, when there is a difference between the detected value and the estimated value of the feed pressure, it can be determined that the relief valve is abnormal based on the detected value and the estimated value of the feed pressure.

  According to the second aspect of the present invention, the feed pressure estimation means estimates the feed pressure based on the rotation speed of the feed pump, and the abnormality determination means determines the feed pressure detection value in a region where the rotation speed is higher than a predetermined value. Is higher than the estimated value over a predetermined range, it is determined that the relief valve is closed and stuck.

Since the feed pressure of the feed pump changes according to the rotation speed of the feed pump, the feed pressure of the feed pump can be estimated with high accuracy based on the rotation speed of the feed pump.
Further, in a region where the rotation speed of the feed pump is higher than a predetermined value, the feed pressure exceeds the opening pressure of the relief valve. Therefore, if the relief valve is normal, the relief valve is opened and the feed pressure is reduced. However, if the relief valve is not opened and is fixedly closed, the detected value of the feed pressure becomes higher than the estimated value beyond the predetermined range in the region where the rotation speed of the feed pump is higher than the predetermined value. In other words, in a region where the rotation speed of the feed pump is higher than a predetermined value, it can be determined that the relief valve is fixedly closed when the detected value of the feed pressure becomes higher than the estimated value beyond the predetermined range.

  According to the third aspect of the present invention, the feed pressure estimation means estimates the feed pressure based on the rotation speed of the feed pump, and the abnormality determination means determines that the detected value is an estimated value in a region where the rotation speed is lower than a predetermined value. If it is lower than the predetermined range, it is determined that the relief valve is stuck open.

  Since the feed pressure of the feed pump changes according to the rotation speed of the feed pump, the feed pressure of the feed pump can be estimated with high accuracy based on the rotation speed of the feed pump.

  Further, in a region where the rotation speed of the feed pump is lower than a predetermined value, the feed pressure is lower than the opening pressure of the relief valve. Therefore, if the relief valve is normal, the relief valve is closed. However, if the relief valve is not closed but is fixed open, the detected value of the feed pressure becomes lower than the estimated value beyond the predetermined range in the region where the rotational speed of the feed pump is lower than the predetermined value. In other words, in a region where the rotation speed of the feed pump is lower than the predetermined value, it can be determined that the relief valve is stuck open when the detected value of the feed pressure becomes lower than the estimated value by exceeding a predetermined range.

  According to a fourth aspect of the present invention, the abnormality determining means determines the abnormality of the relief valve based on the change in the detected value of the feed pressure and the change in the estimated value of the feed pressure when the operation of the internal combustion engine is stopped. To do.

When the operation of the internal combustion engine is stopped, the operation of the feed pump is also stopped. Therefore, the residual pressure detected by the pressure sensor between the feed pump and the fuel filter is lowered by gradually leaking fuel to the low pressure side. If the relief valve is normal, the detected value of the feed pressure decreases at substantially the same rate as the estimated value of the feed pressure when the engine is stopped. On the other hand, if the relief valve is abnormal, when the engine is stopped, the change in the detected value of the feed pressure should be different from the change in the estimated value of the feed pressure. The abnormality of the relief valve can be determined based on the change in the detected value and the change in the estimated value of the feed pressure.

  According to the fifth aspect of the present invention, when the operation of the internal combustion engine is stopped, the abnormality determination unit is configured to relieve when the detected value of the feed pressure decreases earlier than the predetermined time with respect to the estimated value of the feed pressure. It is determined that the valve is stuck open.

  When the relief valve is stuck open, when the operation of the internal combustion engine stops and the feed pump stops, the detected value of the feed pressure is higher than the estimated value of the feed pressure when the relief valve is normally closed. Declines quickly. Therefore, for example, when the detected value of the feed pressure drops to the atmospheric pressure earlier than the estimated value, it can be determined that the relief valve is stuck open.

  The functions of the plurality of means provided in the present invention are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A fuel supply system according to an embodiment of the present invention is shown in FIG.
(Fuel supply system 10)
The accumulator fuel supply system 10 of this embodiment supplies fuel pressurized by the fuel supply pump 30 to a fuel injection valve 80 that injects fuel into a cylinder of a four-cylinder diesel engine (not shown), for example.

  The fuel supply pump 30 includes a feed pump 32, a metering valve 40, a high-pressure pump 50, and the like, and the high-pressure pump 50 pressurizes fuel sucked up from the fuel tank 12 by the feed pump 32.

  The filters 14 and 34 are installed in the fuel passage 200 where the feed pump 32 sucks fuel from the fuel tank 12 and removes foreign matters in the fuel before the fuel is sucked into the feed pump 32. In FIG. 1, filters 14 and 34 and a filter 38 described later are relatively coarse filters such as a metal mesh.

  The priming pump 16 bypasses the feed pump 32 via the bypass passage 202 and supplies fuel to the downstream side of the feed pump 32 when the vehicle is assembled. The check valve 18 installed in the bypass passage 202 prevents the back flow of fuel from the fuel filter 20 to the bypass passage 202.

  The fuel filter 20 is installed on the downstream side of the feed pump 32. For this reason, the feed pressure of the feed pump 32 is applied to the fuel filter 20. Thus, the fuel filter 20 is less likely to be clogged than the filters 14 and 34 installed on the fuel suction side of the feed pump 32 and on the upstream side of the feed pump 32. As a result, a filter element that is finer than the filters 14 and 34 can be used for the fuel filter 20, so that the filtration performance of the fuel filter 20 is higher than that of the filters 14 and 34.

  A pressure sensor 22 is installed between the feed pump 32 and the fuel filter 20. The pressure sensor 22 outputs a detection signal corresponding to the fuel pressure between the feed pump 32 and the fuel filter 20, that is, the feed pressure of the feed pump 32.

The relief valve 24 opens when the fuel pressure applied to the fuel filter 20 exceeds a predetermined pressure, and discharges excess fuel from the escape passage 204 to the fuel tank 12.
The feed pump 32 is a known trochoid pump or vane pump. The feed pump 32 is rotationally driven by the camshaft 52 in the same manner as the high-pressure pump 50. The camshaft 52 is rotationally driven by the crankshaft of the engine. As shown by the solid lines 300 in FIGS. 2A and 2B, the feed pressure Fp of the feed pump 32 increases as the feed pump speed Np increases. However, when the feed pump speed Np exceeds Np0 and the feed pressure exceeds a predetermined pressure, which is the valve opening pressure of the relief valve 36, the relief valve 36 opens, so the feed pump speed Np is Np0. If it exceeds, the rate of increase of the feed pressure decreases.

  The relief valve 36 opens when the feed pressure of the feed pump 32 exceeds a predetermined pressure that is the opening pressure of the relief valve 36. As a result, the fuel on the downstream side of the feed pump 32 is returned from the relief valve 36 to the upstream side of the feed pump 32, so that the feed pressure of the feed pump 32 is reduced. The relief valve 36 corresponds to the relief valve described in the claims.

  The fuel from which foreign matter has been removed by the fuel filter 20 passes through the fuel passage 210 and is supplied to the metering valve 40. The filter 38 is installed on the upstream side of the metering valve 40 and removes foreign matters in the fuel supplied to the metering valve 40.

  The metering valve 40 is an electromagnetic valve whose opening degree is controlled based on the engine operating state. When the opening of the metering valve 40 is controlled, the fuel intake amount sucked into the high-pressure pump 50 is adjusted, and the fuel discharge amount discharged from the high-pressure pump 50 is adjusted.

  The fuel passage 212 returns the fuel leaking from the metering valve 40 to the upstream side of the feed pump 32 when the metering valve 40 is closed. The fuel passage 214 supplies part of the fuel supplied from the feed pump 32 to the cam chamber of the high-pressure pump 50 as lubricating oil.

  The plunger 56 of the high-pressure pump 50 reciprocates as the cam 54 rotates together with the cam shaft 52, and pressurizes the fuel sucked into the pressurizing chamber. Two plungers 56 are installed on the opposite side in the radial direction across the camshaft 52.

  The intake valve 60 opens when fuel is sucked into the pressurizing chamber from the metering valve 40 and closes when fuel is discharged from the pressurizing chamber. On the other hand, the discharge valve 62 is closed when fuel is sucked into the pressurizing chamber from the metering valve 40, and is opened when fuel is discharged from the pressurizing chamber.

  The fuel discharged from the high-pressure pump 50 is supplied to the common rail 70 through the fuel passage 216. The common rail 70 accumulates the fuel supplied from the high pressure pump 50. The pressure limiter 72 opens when the fuel pressure in the common rail 70 (hereinafter also referred to as common rail pressure) exceeds a predetermined pressure, and reduces the common rail pressure. When the pressure limiter 72 is opened, the fuel in the common rail 70 is discharged from the fuel passage 220 to the fuel tank 12. The fuel leaking from the high-pressure pump 50 and the fuel injection valve 80 is also discharged into the fuel passage 220.

The fuel accumulated in the common rail 70 is injected from the fuel injection valve 80 into the cylinder of the diesel engine.
An electronic control unit (ECU) 90 as a fuel supply control device is configured by a microcomputer centering on a CPU, ROM, RAM, flash memory, and the like. Then, the ECU 90 takes in detection signals from various sensors including the pressure sensor 22, the accelerator opening sensor, and the engine speed sensor, and controls the engine operating state.

  For example, the ECU 90 regulates the fuel discharge amount of the high-pressure pump 50 by controlling the amount of current supplied to the metering valve 40 and adjusting the fuel intake amount of the high-pressure pump 50. Further, the ECU 90 controls the fuel injection amount of the fuel injection valve 80, the fuel injection timing, and the multi-stage injection pattern in which pilot injection, post injection, etc. are performed before and after the main injection.

The ECU 90 functions as the following means by a control program stored in the ROM or flash memory.
(Feed pressure detection means)
The ECU 90 detects the feed pressure of the feed pump 32 based on the detection signal of the pressure sensor 22 installed between the feed pump 32 and the fuel filter 20.

(Feed pressure estimation means)
The feed pressure of the feed pump 32 is determined by the discharge amount of the feed pump 32, and the discharge amount of the feed pump 32 is determined by the rotation speed of the feed pump 32. As described above, since the feed pump 32 is rotationally driven by the camshaft 52, the rotational speed of the feed pump 32 is determined by the engine rotational speed (Ne). The ECU 90 stores the relationship between the rotation speed Np of the feed pump 32 and the feed pressure Fp as a characteristic indicated by a solid line 300 in FIG. Thereby, the ECU 90 can estimate the feed pressure with high accuracy based on the rotation speed of the feed pump 32.

(Abnormality judgment means)
The ECU 90 detects the feed pressure detection value of the feed pump 32 detected by the feed pressure detection means based on the detection signal of the pressure sensor 22, and the feed pressure estimated by the feed pressure estimation means based on the rotation speed Np of the feed pump 32. Based on the difference from the estimated value, it is determined whether or not the relief valve 36 is abnormal. Hereinafter, abnormality determination of the relief valve 36 will be described.

(1) Closed valve locking If the relief valve 36 is locked closed due to foreign matter biting, etc., the relief is performed even if the rotation speed of the feed pump 32 exceeds Np0 and the feed pressure exceeds the opening pressure of the relief valve 36. The valve 36 does not open and remains closed. As a result, in a region where the rotation speed of the feed pump 32 is higher than Np0, the feed pressure becomes higher than a predetermined range as indicated by a dotted line 302 with respect to the solid line 300 at normal time shown in FIG. . Therefore, the ECU 90 determines that the detected value of the feed pressure detected by the feed pressure detecting means is within a predetermined range than the estimated value of the feed pressure estimated by the feed pressure estimating means in the region where the rotation speed of the feed pump 32 is higher than Np0. When it is higher than this, it is determined that the relief valve 36 is stuck closed.

(2) Fixed valve opening If the relief valve 36 is fixed open due to foreign matter biting or the like, the relief valve 36 is opened even when the rotational speed Np that does not open normally is smaller than Np0. Yes. As a result, in a region where the rotation speed of the feed pump 32 is lower than Np0, the feed pressure decreases beyond a predetermined range as indicated by a dotted line 304 with respect to the normal solid line 300 shown in FIG. Accordingly, in the region where the rotation speed of the feed pump 32 is lower than Np0, the ECU 90 has a detected value of the feed pressure detected by the feed pressure detecting means within a predetermined range than the estimated value of the feed pressure estimated by the feed pressure estimating means. When it is lower than the above, it is determined that the relief valve 36 is stuck open.

  When the engine is stopped, the detected value of the residual pressure detected by the pressure sensor 22 between the feed pump 32 and the fuel filter 20 gradually decreases as indicated by the solid line 310 in FIG.

  However, if the relief valve 36 is fixed open, the residual pressure between the feed pump 32 and the fuel filter 20 decreases to atmospheric pressure when the relief valve 36 is normal, as indicated by a dotted line 312 in FIG. It drops to atmospheric pressure earlier than the predetermined time required. The ECU 90 detects the residual pressure between the feed pump 32 and the fuel filter 20 when the engine is stopped, that is, the detected value of the feed pressure detected based on the detection signal of the pressure sensor 22 is the estimated value of the feed pressure. On the other hand, if the pressure falls to atmospheric pressure earlier than the predetermined time, it is determined that the relief valve 36 is stuck open.

(Abnormality judgment)
Next, an abnormality determination routine for determining abnormality of the relief valve 36 will be described based on the flowcharts shown in FIGS. FIG. 3 is an abnormality determination routine during engine operation, and FIG. 4 is an abnormality determination routine during engine stop. The routines of FIGS. 3 and 4 are always executed. In FIG. 3 and FIG. 4, “S” represents a step.

(Abnormality judgment routine during engine operation)
In S400 of FIG. 3, the ECU 90 determines whether the rotational speed Np of the feed pump 32 is higher than a predetermined rotational speed Np0.

  When the rotation speed Np of the feed pump 32 is higher than the predetermined rotation speed Np0 (S400: Yes), in S402, the ECU 90 detects the feed pressure detected value Psout as a value obtained by adding the tolerance Pt to the estimated feed pressure value Fp (Fp + Pt). It is judged whether it is higher than. If Psout> Fp + Pt (S402: Yes), the ECU 90 determines that the relief valve 36 is fixedly closed (S404). When the relief valve 36 is fixedly closed, the ECU 90 preferably notifies the driver of the abnormality of the relief valve 36 by a warning light or the like. Thereby, appropriate measures, such as exchanging the relief valve 36, can be implemented quickly.

  If the relief valve 36 is fixedly closed, the feed pressure cannot be reduced even if the feed pressure exceeds a predetermined pressure, so that the feed pressure increases excessively and the fuel filter 20 may be damaged. When the fuel filter 20 is damaged, foreign matter may be caught in the sliding portion of the high-pressure pump 50 or the fuel injection valve 80 on the downstream side of the fuel filter 20 or the valve portion of the fuel injection valve 80.

  Thus, by notifying the abnormality that the relief valve 36 is stuck closed and replacing the relief valve 36, it is possible to prevent the fuel filter 20 from being damaged and prevent foreign matter from flowing into the downstream side of the fuel filter 20.

If Psout ≦ Fp + Pt (S402: No), the ECU 90 determines that the relief valve 36 is not locked open, and ends this routine.
When the rotation speed Np of the feed pump 32 is equal to or lower than the predetermined rotation speed Np0 (S400: No), the ECU 90 in S406, the detected value Psout of the feed pressure is a value obtained by subtracting the tolerance Pt from the estimated value Fp of the feed pressure (Fp−Pt). ). If Psout <Fp−Pt (S406: Yes), the ECU 90 determines that the relief valve 36 is stuck open (S408). When the relief valve 36 is stuck open, it is desirable that the ECU 90 informs the driver of the abnormality of the relief valve 36 by a warning light or the like. Thereby, appropriate measures, such as exchanging the relief valve 36, can be implemented quickly.

  When the relief valve 36 is firmly fixed, the relief valve 36 is opened even when the engine speed is low, and the feed pressure of the feed pump 32 is lowered. Therefore, the discharge amount of the high-pressure pump 50 is insufficient and the common rail pressure is reduced. Cannot accumulate to the target pressure. As a result, the engine operating state becomes unstable when the engine speed is low, and the engine may stop. Further, the engine may not be started because the feed pressure of the feed pump 32 is low.

  Accordingly, by notifying the abnormality that the relief valve 36 is stuck open and replacing the relief valve 36, the engine operating state is stabilized even when the engine speed is low, and engine start-up failure can be prevented.

If Psout ≧ Fp−Pt (S406: No), the ECU 90 determines that the relief valve 36 is not stuck open, and ends this routine.
(Abnormality judgment routine when the engine is stopped)
In S410 of FIG. 4, the ECU 90 determines whether the engine has stopped and the rotation speed Np of the feed pump 32 has become zero. If Np = 0 is not satisfied (S410: No), it is determined that the engine is not stopped, and the ECU 90 ends this routine.

  If Np = 0 (S410: Yes), the ECU 90 determines that the engine has stopped, and counts the elapsed time after the engine stops (S412). When the predetermined time has elapsed (S414: Yes), in S416, the ECU 90 determines that the detected elapsed time T when the detected value of the residual pressure between the feed pump 32 and the fuel filter 20 becomes 0 corresponding to the atmospheric pressure is the relief valve 36. It is shorter than the estimated elapsed time t estimated that the residual pressure between the feed pump 32 and the fuel filter 20 becomes 0 at normal time, that is, the detected value of the feed pressure is shorter than the predetermined time with respect to the estimated value of the feed pressure. Determine if it falls early.

  When the detected elapsed time T is shorter than the estimated elapsed time t (S416: Yes), the ECU 90 determines that the relief valve 36 is stuck open. When the relief valve 36 is stuck open, as described above, the ECU 90 desirably notifies the driver of the abnormality of the relief valve 36 by a warning light or the like. Thereby, appropriate measures, such as exchanging the relief valve 36, can be implemented quickly. As a result, even when the engine speed is low, the engine operating state is stabilized, and the next engine starting failure can be prevented.

When the detected elapsed time T is equal to or longer than the estimated elapsed time t (S416: No), the ECU 90 determines that the relief valve 36 is not stuck open and ends this routine.
In the above-described embodiment, in the fuel supply system in which the fuel filter is installed on the downstream side of the feed pump and the relief valve opens when the feed pressure of the feed pump exceeds a predetermined pressure, the pressure sensor reduces the feed pressure. Based on the detected value of the feed pressure detected by the motor 22 and the estimated value of the feed pressure estimated from the operating state such as the rotation speed of the feed pump 32, the relief valve 36 is fixedly open or fixedly closed. It was judged whether it was abnormal or not. As a result, when the relief valve 36 is fixedly open or closed, appropriate measures such as replacing the relief valve 36 can be promptly implemented.

[Other Embodiments]
In the above embodiment, the pressure sensor 22 is installed between the feed pump 32 and the fuel filter 20, that is, upstream of the fuel filter 20, and the feed pressure of the feed pump 32 is detected based on the detection signal of the pressure sensor 22. In contrast to this, even if a pressure sensor is installed on the downstream side of the fuel filter 20 in addition to the upstream side of the fuel filter 20, the differential pressure between the upstream and downstream sides of the fuel filter 20 can be detected from the detected pressures of both pressure sensors. Good. By detecting the differential pressure between the upstream and downstream of the fuel filter 20, the degree of clogging of the fuel filter 20 can be detected. If a differential pressure sensor is installed without installing a pressure sensor upstream and downstream of the fuel filter 20, the degree of clogging of the fuel filter 20 can be detected. However, since the differential pressure sensor cannot detect the feed pressure of the feed pump 32, it is not suitable for the present invention.

  In the above-described embodiment, the example in which the present invention is applied to the fuel supply system of a common rail type diesel engine in which the fuel supplied from the feed pump 32 is pressurized by the high-pressure pump 50 and accumulated in the common rail 70 has been described. On the other hand, if a fuel filter is installed on the downstream side of the feed pump and the relief valve opens and the feed pressure is reduced when the feed pressure of the feed pump exceeds a predetermined pressure, the common rail type or diesel engine However, the present invention may be applied to any fuel supply system for an internal combustion engine.

  In the above embodiment, the functions of the feed pressure detection means, the feed pressure estimation means, and the abnormality determination means are realized by the ECU 90 whose functions are specified by the control program. On the other hand, at least a part of the functions of the above means may be realized by hardware whose function is specified by the circuit configuration itself.

  As described above, the present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

The block diagram which shows the fuel supply system by this embodiment. (A), (B) is a characteristic diagram which shows the relationship between the rotation speed of a feed pump, and fuel pressure, (C) is a characteristic diagram which shows the relationship between the time passage after engine stop and a residual pressure. The flowchart which shows abnormality determination of the relief valve during engine operation. The flowchart which shows abnormality determination of the relief valve at the time of an engine stop.

Explanation of symbols

10: Fuel supply system, 20: Fuel filter, 22: Pressure sensor, 30: Fuel supply pump, 32: Feed pump, 36: Relief valve, 50 high pressure pump, 70: Common rail, 80: Fuel injection valve, 90: ECU ( (Fuel supply control device, feed pressure detection means, feed pressure estimation means, abnormality determination means)

Claims (6)

A feed pump for supplying fuel to be injected into a cylinder of the internal combustion engine by a fuel injection valve;
A fuel filter installed on the downstream side of the feed pump to remove foreign matters in the fuel supplied from the feed pump;
A relief valve that opens when the feed pressure of the feed pump exceeds a predetermined pressure to reduce the feed pressure;
In a fuel supply control device used for a fuel supply system comprising:
A pressure sensor installed between the feed pump and the fuel filter;
A feed pressure detecting means for detecting a feed pressure of the feed pump based on a detection signal of the pressure sensor;
A feed pressure estimating means for estimating the feed pressure based on an operating state of the feed pump;
An abnormality determining means for determining an abnormality of the relief valve based on a detected value of the feed pressure detected by the feed pressure detecting means and an estimated value of the feed pressure estimated by the feed pressure estimating means;
A fuel supply control device comprising: The feed pressure estimating means estimates the feed pressure based on the rotation speed of the feed pump,
The abnormality determining means determines that the relief valve is closed and fixed when the detected value is higher than the estimated value beyond a predetermined range in a region where the rotational speed is higher than a predetermined value.
The fuel supply control device according to claim 1. The feed pressure estimating means estimates the feed pressure based on the rotation speed of the feed pump,
The abnormality determining means determines that the relief valve is stuck open when the detected value is lower than a predetermined range below the estimated value in a region where the rotational speed is lower than a predetermined value.
The fuel supply control device according to claim 1, wherein the fuel supply control device is a fuel supply control device.   The abnormality determination unit determines abnormality of the relief valve based on a change in the detected value and a change in the estimated value when the operation of the internal combustion engine is stopped. The fuel supply control device according to any one of the above.   When the operation of the internal combustion engine is stopped, the abnormality determination unit determines that the relief valve is stuck open when the detected value decreases earlier than a predetermined time with respect to the estimated value. The fuel supply control device according to claim 4. A common rail that supplies fuel accumulated in a fuel injection valve that injects fuel into a cylinder of the internal combustion engine;
A high pressure pump for supplying pressurized fuel to the common rail;
A feed pump for supplying fuel sucked up from a fuel tank to the high-pressure pump;
A relief valve that opens when the feed pressure of the feed pump exceeds a predetermined pressure to reduce the feed pressure;
The fuel supply control device according to any one of claims 1 to 5,
A fuel supply system comprising:

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