JP2011064108A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly detect an increase in leakage amount caused in a high-pressure path of a common rail or the like, in a common rail type fuel injection device. <P>SOLUTION: When accelerator-on operation is turned to accelerator-off operation, a pressure drop amount ΔPc of the common rail 20 is detected. When the pressure drop amount ΔPc is greater than a predetermined drop amount ΔPco, it is determined that the leakage amount is increased to the extent of causing interference with fuel injection control. Meanwhile, when the detected pressure drop amount ΔPc is less than the predetermined drop amount ΔPco, it is determined that the leakage amount is not increased to the extent of causing interference with the fuel injection control. Thereby, in the common rail type fuel injection device 10, it is possible to certainly detect the increase in leakage amount caused in the high-pressure path L1 (especially, an injector 30) of the common rail 20 or the like. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a common rail (stock pressure) type fuel injection device, and is particularly effective when applied to an internal combustion engine for a vehicle.

  A common rail fuel injection device (hereinafter abbreviated as a fuel injection device) is a fuel supply device mainly used for a diesel internal combustion engine. Specifically, the fuel injection device includes a high-pressure pump that pressurizes and supplies fuel stored in a fuel tank, a common rail that compresses high-pressure fuel supplied from the high-pressure pump, and high-pressure fuel that is stored in the common rail. An injector (injection valve) for supplying an injection to an internal combustion engine (hereinafter referred to as an engine) is provided (see, for example, Patent Document 1).

  In the fuel injection device for vehicles, when the engine load or the accelerator pedal depression amount is large, the fuel pressure in the common rail is raised to, for example, 100 MPa or more, and the injector is opened to supply high pressure fuel to the engine. There is a case.

JP 2003-155948 A

  Incidentally, as is well known, an injector has a valve body that opens and closes an injection port. However, when a high pressure is applied, a small amount of fuel leaks (leaks) from the gap. The amount is called the leak amount. For example, when the amount of leakage increases due to wear or the like, the pressure in the common rail cannot be increased to the control target pressure (for example, 100 MPa) even if fuel is supplied from the high pressure pump to the common rail.

  If the pressure in the common rail falls below the control target pressure, the amount and timing of fuel supplied to the engine cannot be precisely controlled, causing problems such as a decrease in engine output and an increase in exhaust emissions. It tends to occur.

  An object of the present invention is to reliably detect an abnormal increase in the amount of leakage generated in an injector in a common rail fuel injection device in view of the above points.

  In order to achieve the above object, the present invention provides a fuel injection device for supplying fuel to an internal combustion engine (50), wherein fuel stored in a fuel tank (12) is added. A high-pressure pump (16) for supplying pressure, a common rail (20) for storing high-pressure fuel supplied from the high-pressure pump (16), and high-pressure fuel stored in the common rail (20) for injection into the internal combustion engine (50) The injector (30) to be supplied, the pressure sensor (22) for detecting the pressure in the high pressure path (L1) from the high pressure pump (16) through the common rail (20) to the injector (30), and the fuel by the injector (30) The high pressure circuit (100) based on the pressure detected by the pressure sensor (22) when the fuel injection by the injector (30) is changed to the stopped state from the state where the injection is performed. It is determined whether the pressure drop detected by the pressure drop detecting means (S10 to S80, 40) and the pressure drop detecting means (S10 to S80, 40) are larger than the predetermined drop amount. And determining means (S90, 40).

  In the first aspect of the invention, since it is determined whether or not the pressure drop detected by the pressure drop detection means (S10 to S80, 40) is larger than the predetermined drop, the detected pressure drop is If it is larger than the predetermined drop amount, it can be determined that an increase in the leak amount that hinders fuel injection control has occurred, while the detected pressure drop amount is equal to or less than the predetermined drop amount. In some cases, it can be determined that there has not been an increase in the amount of leakage that hinders fuel injection control.

  In addition, when fuel injection is performed, fuel is normally supplied from the high-pressure pump (16) to the common rail (20) accordingly, so that the pressure in the high-pressure path (L1) increases. On the other hand, when the fuel injection is stopped, the fuel supply from the high pressure pump (16) to the common rail (20) is stopped accordingly until a predetermined condition is satisfied. If not, the pressure drop amount while the fuel supply is stopped is a pressure drop only due to the influence of the leak amount generated in the injector. Therefore, if the pressure drop amount is detected at the timing when the fuel injection is stopped, it is possible to reliably detect an abnormal increase in the leak amount.

  Therefore, in the invention described in claim 1, by detecting the pressure drop when the fuel injection by the injector (30) is changed to the state where the fuel injection by the injector (30) is stopped, An abnormal increase in the leak amount in the high-pressure path (L1) can be reliably detected.

  Note that “until a predetermined condition is satisfied” means, for example, “the rotational speed of the internal combustion engine (50) decreases to a rotational speed that does not stop the internal combustion engine (50) (for example, idling rotational speed). It is a condition such as “to”.

  By the way, in order to quickly reduce the pressure in the common rail (20), the circuit (100) for connecting the high-pressure circuit (100) and the fuel tank (12) side is opened and closed as in the invention described in claim 2. There is a fuel injection device provided with a pressure reducing valve (24).

  The invention according to claim 2 is characterized by comprising valve closing means (S55, 40) for closing the pressure reducing valve (24) when the pressure drop amount is detected, so that the pressure reducing valve (24) is provided. The pressure drop amount can be detected in a state in which the influence of is eliminated. Therefore, it is possible to accurately detect an abnormal increase in the leak amount.

  In the invention according to claim 3, the flow adjustment is performed so that the amount of fuel supplied from the high-pressure pump (16) is adjusted within a predetermined adjustment range so that the pressure in the common rail (20) becomes the control target pressure. The control means (18) is provided, and the pressure drop detection means (S10 to S80, 40) increases the pressure in the common rail (20) to the control target pressure in the adjustment within the adjustment range by the flow control means (18). The feature is that the amount of pressure drop is detected when it is no longer possible.

  Thereby, in the invention according to claim 3, when the detected pressure drop amount is larger than the predetermined drop amount, it can be determined that the leak amount is increased by the injector (30), When the detected pressure drop amount is equal to or less than the predetermined drop amount, it can be determined that a sufficient amount of fuel is not supplied from the high-pressure pump (16) to the common rail (20). Therefore, it is possible to specify which of the injector (30) and the high-pressure pump (16) has a fault.

  By the way, even when the amount of leak does not increase to the extent that hinders fuel injection control (hereinafter referred to as normal), the pressure in the high pressure path (L1) decreases exponentially. Therefore, when the pressure at the time when the pressure drop detecting means (S10 to S80, 40) starts detecting the pressure drop amount is low, the detected pressure drop amount is small, so that the pressure drop is increased due to an increase in the leak amount. It is difficult to determine whether it has occurred or a normal pressure drop.

  On the other hand, in the invention according to claim 4, the pressure drop detecting means (S10 to S80, 40), when the detected pressure when the fuel injection by the injector (30) is stopped is equal to or higher than a predetermined pressure, It is characterized by detecting the amount of pressure drop.

  Thus, in the invention according to claim 4, since the pressure drop amount is detected in a region where the rate of change of pressure becomes large, whether the pressure drop has occurred due to an abnormal increase in the leak amount, or the pressure at normal time It is possible to easily determine whether it is a descent.

  The invention according to claim 5 further comprises warning means (S100, 40) for issuing a warning when the determination means (S90, 40) determines that the pressure drop amount is larger than the predetermined drop amount. It is what.

  Incidentally, the reference numerals in parentheses for each of the above means are examples showing the correspondence with the specific means described in the embodiments described later, and the present invention is indicated by the reference numerals in the parentheses of the above respective means. It is not limited to a specific hand or the like.

It is a mimetic diagram showing an outline of fuel injection device 10 concerning an embodiment concerning the present invention. It is a flowchart which shows the fuel leak detection control which concerns on 1st Embodiment which concerns on this invention. It is a graph which shows the relationship between fuel pressure and time. It is a flowchart which shows the fuel leak detection control which concerns on 2nd Embodiment which concerns on this invention. It is a flowchart which shows the starting determination control which concerns on 3rd Embodiment concerning this invention. It is a flowchart which shows the fuel leak detection control which concerns on 3rd Embodiment which concerns on this invention.

In the present embodiment, the fuel injection device according to the present invention is applied to a fuel injection device for a diesel engine for a vehicle. Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
1. Configuration of fuel injection device (see Fig. 1)
The fuel injection device 10 according to the present embodiment is a so-called pressure accumulation type (common rail type) fuel injection device. Specifically, as shown in FIG. 1, the feed pump 14, the high pressure pump 16, the flow rate adjusting valve 18, the common rail 20, the pressure sensor 22, the pressure reducing valve 24, the injector 30, and an electronic control unit (hereinafter referred to as ECU). 40 and an electronic drive unit (hereinafter referred to as EDU) 42 and the like, and injects fuel into each cylinder of a four-cylinder diesel internal combustion engine (hereinafter referred to as engine) 50.

  The feed pump 14 sucks fuel from the fuel tank 12 and supplies the fuel to the high-pressure pump 16. The high-pressure pump 16 sucks into the pressurizing chamber by reciprocating the plunger as the cam of the camshaft rotates. This is a known pump for pressurizing the fuel.

  The flow rate adjusting valve 18 is provided at the discharge portion (exit) of the high-pressure pump 16 and adjusts the amount of fuel supplied to the common rail 20 so that the pressure in the common rail 20 is controlled in cooperation with the high-pressure pump 16. In this embodiment, the flow rate adjusting valve 18 and the high-pressure pump 16 constitute a pressure supply means for supplying fuel under pressure.

  Incidentally, since the high-pressure pump 16 is operated by obtaining power from the engine 50, the high-pressure pump 16 itself cannot be directly controlled. However, the operation (opening degree) of the flow rate adjusting valve 18 is duty-controlled by the ECU 40. Therefore, the amount of fuel supplied to the common rail 20 can be adjusted by controlling the operation of the flow rate adjusting valve 18.

  The discharge portion of the high-pressure pump 16 is provided with a check valve 16A that prevents the fuel discharged from the high-pressure pump 16 toward the common rail 20 from flowing back to the high-pressure pump 16. Only when the pressure in the common rail 20 becomes larger than the pressure in the common rail 20, the check valve 16A is opened, and the fuel is discharged to the common rail 20 side.

  The common rail 20 is a stock pressure vessel that accumulates fuel pumped from the high-pressure pump 16 and holds the fuel pressure at a predetermined pressure corresponding to the engine operating state. The pressure sensor 22 is connected to the inlet side of the common rail 20. Pressure detecting means for detecting the pressure in the common rail 20. For this reason, the pressure sensor 22 detects the pressure in the high-pressure path L1 from the high-pressure pump 16 through the common rail 20 to the injector 30.

  The pressure reducing valve 24 is a pressure reducing means for reducing the fuel pressure in the common rail 20 by discharging the fuel in the common rail 20 to the low-pressure return passage 100 communicating with the fuel tank 12 by opening the valve.

  The pressure reducing valve 24 according to the present embodiment is a relief valve (JIS B 0125 No. 14-) that acts on the valve body so that the elastic force of elastic means such as a spring is opposed to the pressure in the high pressure path L1 (common rail 20). 1), the valve is opened when the pressure in the high pressure path L1 exceeds the set pressure by the spring, and the high pressure fuel in the high pressure path L1 is discharged to the fuel tank 12 side.

  The plurality of injectors 30 are fuel injection valves that are connected in parallel to the common rail 20 and inject fuel accumulated in the common rail 20 into each cylinder. The injector 30 is closed by a nozzle needle. This is a known electromagnetically driven or piezoelectrically driven valve that controls the fuel injection amount by controlling the pressure in a control chamber that applies fuel pressure in the direction.

  The ECU 40 is a control means constituted by a well-known microcomputer including a rewritable nonvolatile memory such as a CPU, ROM, RAM, and flash memory. The flow rate adjusting valve 18 and the injector 30 are controlled by the ECU 40. . The injector 30 is not directly controlled by the ECU 40 but is indirectly controlled by the ECU 40 via the EDU 42 that drives the injector 30.

  Further, the ECU 40 detects the rotation speed of the engine speed, the accelerator sensor S2 that detects the opening degree of the accelerator pedal (depression amount), the crank angle sensor S3 that detects the crank angle, and the rotation speed of the high-pressure pump 16. The operating states of the engine 50 and the fuel injection device 10 are acquired based on detection signals from various sensors such as the rotation speed sensor 28 and the pressure sensor 22.

  Then, in order to control the engine 50 to the optimum operating state, the ECU 40 energizes the flow rate adjustment valve 18 and the injector 30 according to the program stored in advance in the ROM or flash memory based on the acquired engine operating state. (Energization duty) is controlled.

  Specifically, a map indicating the discharge amount characteristic of the high-pressure pump 16 with respect to the energization amount to the flow rate adjusting valve 18 (hereinafter referred to as a discharge amount characteristic map) is stored in the flash memory, and the ECU 40 stores it in the flash memory. Based on the discharge amount characteristic map, the energization to the flow rate adjustment valve 18 is feedback controlled by PID control so that the fuel pressure of the common rail 20 acquired from the pressure sensor 22 becomes the control target pressure.

  As described above, the ECU 40 controls the flow rate adjustment valve 18 so that the fuel pressure of the common rail 20 becomes the control target pressure. However, the injection port cannot be completely closed due to, for example, a foreign object biting into the injector 30. When the state occurs, the fuel leaked from the injector 30 returns to the fuel tank 12 side. Therefore, even if fuel is supplied from the high-pressure pump 16 to the common rail 20, the pressure in the common rail 20 can be increased to the control target pressure. become unable.

  Therefore, the ECU 40 detects a pressure drop amount in the high pressure path L1 at a predetermined timing, thereby detecting whether or not an abnormality has occurred in the injector 30 or the like (hereinafter referred to as fuel leak detection control). Running. Details of the fuel leak detection control will be described below.

2. Fuel leak detection control (see Fig. 2)
The fuel leak detection control flow shown in FIG. 2 is started (executed) by the ECU 40 when a vehicle switch (for example, a starter switch) is turned on, and ends when the engine 50 is stopped. A program for executing fuel leak detection control is stored in the ROM or flash memory.

  When the fuel leak detection control is activated, first, a predetermined time (100 hours in the present embodiment) has elapsed since the previous time when the abnormality determination or normality determination (S100 or S110 described later) was executed. Is determined (S10). If it is determined that the elapsed time is less than the predetermined time (S10: NO), S10 is executed again.

  On the other hand, when it is determined that the elapsed time is equal to or longer than the predetermined time (S10: YES), the accelerator depression amount is 0 (hereinafter referred to as accelerator OFF) from the state where the accelerator is depressed (hereinafter referred to as the accelerator ON state). It is determined whether the fuel injection by the injector 30 is stopped from the state where the fuel injection is performed by the injector 30 (S20).

  When the accelerator is turned on, the ECU 40 determines the amount and timing of the fuel to be injected based on the amount of depression and the engine operating state and operates the injector 30. When the accelerator is turned on from the accelerator on, the ECU 40 After the fuel injection is stopped, the fuel injection is resumed when the engine speed decreases to about the idling speed. Therefore, when the accelerator is turned on from the accelerator ON, the fuel injection by the injector 30 is normally stopped from the state where the fuel is injected by the injector 30.

  If it is determined that the accelerator is not on from the accelerator ON (S20: NO), S10 is executed again. On the other hand, if it is determined that the accelerator is off from the accelerator ON (S20: YES), it is determined whether the supply of fuel from the high-pressure pump 16 to the common rail 20 is stopped and the fuel injection by the injector 30 is stopped (S30).

  At this time, when the fuel supply is resumed by the high-pressure pump 16 or when the fuel injection by the injector 30 is resumed (S30: NO), S10 is executed again, while the fuel supply by the high-pressure pump 16 is performed. When it is determined that the fuel injection by the injector 30 is stopped (S30: YES), the pressure in the high pressure path L1 at that time is acquired via the pressure sensor 22, and the acquired The pressure (hereinafter referred to as the first pressure pc1) is stored in the RAM (S40).

  Since the determination of S30 is completed instantaneously, the acquisition timing of the first pressure pc1 is determined when the fuel injection by the injector 30 is stopped, that is, when it is determined in S20 that the accelerator is OFF from the accelerator ON. You can consider it.

  Next, it is determined whether the first pressure pc1 is equal to or higher than the first predetermined pressure A (approximately 80 MPa in the present embodiment) and equal to or lower than the second predetermined pressure B (approximately 160 MPa in the present embodiment) (S50). When it is determined that the first pressure pc1 is not higher than the first predetermined pressure A and lower than the second predetermined pressure B (S50: NO), S10 is executed again.

  In S50, it is also determined whether or not the first pressure pc1 is equal to or lower than the second predetermined pressure B. In this embodiment, the ECU 40 controls the control target pressure in the range of 30 MPa to 160 MPa according to the engine load and the like. Is set to control the flow rate adjustment valve 18 and the pressure in the common rail 20 exceeds 160 MPa, the pressure reducing valve 24 is opened to protect the fuel injection device 10, so that at least the first in S50. It is necessary and sufficient if it is determined whether or not the pressure pc1 is equal to or higher than the first predetermined pressure A.

  When it is determined that the first pressure pc1 is not less than the first predetermined pressure A and not more than the second predetermined pressure B (S50: YES), when it is determined in S20 that the accelerator is turned on from the accelerator on. It is determined whether or not a predetermined time (approximately 5 seconds in this embodiment) has elapsed (S60). If it is determined that the predetermined time has not elapsed (S60: NO), the high pressure pump 16 It is determined whether the fuel supply is stopped and the fuel injection by the injector 30 is stopped (S70).

  At this time, when the fuel supply is resumed by the pressure pump 16 or when the fuel injection by the injector 30 is resumed (S70: NO), S10 is executed again, while the fuel supply by the high-pressure pump 16 is performed. If it is determined that the fuel injection by the injector 30 is stopped (S70: YES), S60 is executed again.

  If it is determined in S60 that the predetermined time has elapsed (S60: YES), the pressure in the high pressure path L1 at that time is acquired via the pressure sensor 22 (S80), and then acquired. It is determined whether or not the pressure difference (= pc1-pc2) between the first pressure pc1 and the first pressure pc1, that is, the pressure drop amount ΔPc of the high pressure path L1 is greater than the predetermined drop amount ΔPco. (S90).

  If it is determined that the pressure drop amount ΔPc is greater than the predetermined drop amount ΔPco (S90: YES), it is considered that the leak amount has increased (occurrence of abnormality) in the high-pressure path L1 (particularly, the injector 30). Then, a warning to that effect is given, and the date when the abnormality is detected is stored in the flash memory (S100), and then the elapsed time used for the determination in S10 is reset to 0 (S120). In the present embodiment, the above warning is executed by turning on a warning light (not shown) provided on the instrument panel of the vehicle.

  On the other hand, when it is determined that the pressure drop amount ΔPc is not larger than the predetermined drop amount ΔPco (S90: NO), the leak amount has not increased (normal) in the high-pressure path L1 (particularly, the injector 30). After it is assumed that there is a date and the normality detection date is stored in the flash memory (S110), S120 is executed. When S120 is executed, S10 is executed again.

3. Features of Fuel Injection Device According to this Embodiment In this embodiment, when the detected pressure drop amount ΔPc is larger than the predetermined drop amount ΔPco, the amount of leak increases to the extent that the fuel injection control is hindered. On the other hand, when the detected pressure drop amount ΔPc is equal to or less than the predetermined drop amount ΔPco, it is determined that the leak amount has not increased to the extent that hinders fuel injection control. In the injection device 10, it is possible to reliably detect an increase in the leak amount in the high-pressure path L <b> 1 such as the common rail 20.

  The predetermined drop amount ΔPco is a value that differs depending on the type of the fuel injection device 10, and it is difficult to theoretically determine the value. Therefore, the predetermined drop amount ΔPco is usually determined by a test using an actual machine when the fuel injection device 10 is developed. Is the value to be

  Further, when fuel injection is executed, fuel is normally supplied from the high-pressure pump 16 to the common rail 20 accordingly, so that the pressure in the high-pressure path L1 increases. On the other hand, when the fuel injection is stopped, the fuel supply from the high-pressure pump 16 to the common rail 20 is stopped accordingly until a predetermined condition is satisfied. Therefore, if there is no increase in the leak amount in the high-pressure path L1, the fuel supply The pressure drop amount ΔPc during the stop is ideally almost absent. Therefore, if the pressure drop amount ΔPc is detected at the timing when the fuel injection is stopped, it is possible to reliably detect an increase in the leak amount of the high-pressure path L1.

  As described above, “until the predetermined condition is satisfied” means, for example, “until the rotational speed of the engine 50 decreases to a rotational speed at which the engine 50 does not stop (for example, idling rotational speed). Is the condition.

  Therefore, in the present embodiment, when the accelerator is turned on from the accelerator ON, that is, when the fuel injection by the injector 30 is changed to the state where the fuel injection by the injector 30 is stopped, the pressure drop amount ΔPc is detected. By doing so, it is possible to reliably detect an increase in the leak amount in the high-pressure path L1.

  “When the accelerator is turned on from the accelerator ON (when the fuel injection by the injector 30 is changed to the state where the fuel injection by the injector 30 is stopped)”, for example, (a) The vehicle is running When the vehicle is decelerated due to the accelerator being turned off, (b) when the vehicle is idle (racing) while the vehicle is stopped is considered.

  By the way, even if the amount of leak does not increase to the extent that hinders fuel injection control (hereinafter referred to as normal), the pressure in the high-pressure path L1 is exponential as shown in FIG. Therefore, when the pressure (first pressure pc1) at the time when the detection of the pressure drop amount ΔPc is started is low (see P′c1 in FIG. 3), the detected pressure drop amount ΔPc is small. For this reason, it is difficult to determine whether a pressure drop has occurred due to an abnormal increase in the leak amount or whether the pressure drop is normal.

  On the other hand, in the present embodiment, when the detected pressure when the fuel injection by the injector 30 is stopped is equal to or higher than the first predetermined pressure A, the pressure drop amount ΔPc is detected, so the rate of change in pressure increases. The pressure drop amount ΔPc is detected in the region. Therefore, it is possible to easily determine whether a pressure drop has occurred due to an abnormal increase in the leak amount or a normal pressure drop.

  The first predetermined pressure A is a different value for each type of the fuel injection device 10, and it is difficult to theoretically determine the value. Therefore, the first predetermined pressure A is usually determined by a test using an actual machine at the time of development of the fuel injection device 10. The value to be determined.

4). Correspondence Relationship between Invention Specific Items and Embodiment In this embodiment, ECU 40 and its control steps S10 to S80 correspond to the pressure drop detection means in the claims, and ECU 40 and its control step S90 determine the claims. The ECU 40 and its control step S100 correspond to warning means in the claims.

(Second Embodiment)
The pressure reducing valve 24 according to the first embodiment is a mechanical relief valve that opens when the pressure in the pressure path L1 exceeds the set pressure by the spring, but this embodiment is an electromagnetic drive such as a coil. The pressure reducing valve 24 is configured by a known electromagnetic valve having a portion. The operation of the pressure reducing valve 24 according to this embodiment is controlled by the ECU 40 via the EDU 42.

  In the present embodiment, the ECU 40 reduces the fuel pressure of the common rail 20 during deceleration operation or the like, and when the pressure of the common rail 20 is not quickly reduced just by reducing the discharge amount from the high-pressure pump 16. Instructs the EDU 42 to open the pressure reducing valve 24, opens the pressure reducing valve 24, discharges the fuel inside the common rail 20 to the return passage 100, and lowers the fuel pressure in the common rail 20.

  In the present embodiment, as the pressure reducing valve 24 is an electromagnetic valve, at the time of fuel leak detection control, as shown in FIG. 4, the first pressure pc1 is equal to or higher than the first predetermined pressure A and the second predetermined pressure. When it is determined that it is equal to or less than B (S50: YES), after the pressure reducing valve 24 is closed (S55), a predetermined time has elapsed since it was determined in S20 that the accelerator was turned on from the accelerator on. It is determined whether or not it has been done (S60). In FIG. 4, the same control steps as those in the first embodiment (FIG. 2) are denoted by the same reference numerals as those in the first embodiment (FIG. 2).

  Thereby, in this embodiment, since the pressure drop amount ΔPc can be detected with the pressure reducing valve 24 being closed when the pressure drop amount ΔPc is detected, the pressure drop amount ΔPc can be detected with the influence of the pressure reducing valve 24 removed. It is possible to detect, and it is possible to accurately detect an increase in the leak amount in the high-pressure path L1.

In this embodiment, S55 and ECU 40 correspond to the valve closing means described in the claims.
(Third embodiment)
In the first and second embodiments, the fuel leak detection control is periodically executed, but in this embodiment, the pressure in the common rail 20 cannot be increased to the control target pressure by the adjustment by the flow rate adjusting valve 18. In this case, fuel leak detection control is executed.

1. Characteristic operation of the fuel injection device according to the present embodiment When the ECU 40 determines the control target pressure according to the engine operating state or the like as described above, the ECU 40 discharges the energization amount (energization duty) corresponding to the determined control target pressure. The flow rate adjustment valve 18 is operated based on the quantity characteristic map. When the fuel pressure acquired by the pressure sensor 22 is lower than the control target pressure, the amount of fuel discharged from the high-pressure pump 16 increases. Thus, the energization amount to the flow rate adjustment valve 18 is changed.

  However, in the present embodiment, the energization amount is not changed without limitation with respect to the energization amount corresponding to the control target pressure (hereinafter referred to as the corresponding energization amount), but within a predetermined adjustment range based on the corresponding energization amount. By changing (adjusting) the energization amount, PID control is performed so that the fuel pressure of the common rail 20 becomes the control target pressure. Incidentally, the adjustment range may be either when changing according to the control target pressure, or when the adjustment range is a constant range regardless of the control target pressure.

  And in this embodiment, it is set as the structure which performs fuel leak detection control, when it becomes impossible to raise the fuel pressure of the common rail 20 to a control target pressure by the change of the energization amount within an adjustment range.

  Hereinafter, characteristic operations in the present embodiment will be described with reference to FIG. In the following description, it is assumed that the amount of fuel supplied from the high-pressure pump 16 to the common rail 20 increases as the energization amount to the flow rate adjustment valve 18 increases.

  The control flow shown in FIG. 5 (hereinafter referred to as activation determination control) is activated by the ECU 40 when the vehicle switch is turned on and ends when the engine 50 is stopped. A program for executing the activation determination control is stored in the ROM or flash memory.

  When the activation determination control is activated, first, it is determined whether or not the corresponding energization amount and the difference between the energization amount after the change (hereinafter, this difference is referred to as the change amount Δi) are the upper limit value of the adjustment range. (S200) When it is determined that the change amount Δi is not the upper limit value (S200: NO), S200 is executed again.

  On the other hand, when it is determined that the change amount Δi is the upper limit value (S200: YES), it is determined whether or not the current pressure in the common rail 20 acquired by the pressure sensor 22 is less than the control target pressure. (S210) When it is determined that the current pressure in the common rail 20 is equal to or higher than the control target pressure (S210: NO), S200 is executed again.

  Further, when it is determined that the current pressure in the common rail 20 is less than the control target pressure (S210: YES), the discharge amount actually discharged with respect to the discharge amount necessary to obtain the control target pressure The fuel leak detection control is executed (S220).

  The fuel leak detection control according to the present embodiment may be either the fuel leak detection control according to the first embodiment or the fuel leak detection control according to the second embodiment. Taking this fuel leak detection control as an example, the fuel leak detection control according to this embodiment will be described.

  In the fuel leak detection control according to the present embodiment, as shown in FIG. 6, “from the previous time when the abnormality determination or normality determination was executed is compared with the fuel leak detection control according to the first embodiment (FIG. 2). The determination step (S10) for determining whether or not the elapsed time has passed has been deleted, and if it is determined in S90 that the pressure drop amount ΔPc is not greater than the predetermined drop amount ΔPco (S90). : NO), a warning that an abnormality (failure) has occurred in the high-pressure pump 16 is executed (S115). Incidentally, the warning in S115 is executed by turning on a warning light (not shown) provided on the instrument panel of the vehicle.

In FIG. 6, the same control steps as those in the first embodiment (FIG. 2) are denoted by the same reference numerals as those in the first embodiment (FIG. 2).
2. Features of Fuel Injection Device According to this Embodiment In S210, when it is determined that the current pressure in the common rail 20 is less than the control target pressure (S210: YES), it is necessary to obtain the control target pressure. The discharge amount actually discharged is insufficient with respect to the discharge amount. The cause of the shortage of discharge amount is as follows. (A) Since the increase in the leak amount from the injector 30 is large, the discharge amount is It is conceivable that there is a shortage and (b) the discharge amount of the high-pressure pump 16 is insufficient in the first place.

  Therefore, in the present embodiment, when the detected pressure drop amount ΔPc is larger than the predetermined drop amount ΔPco, it is determined that the leak amount is increased in the injector 30, while the detected pressure drop amount ΔPc is When it is equal to or less than the predetermined drop amount ΔPco, it is determined that a sufficient amount of fuel is not supplied from the high-pressure pump 16 to the common rail 20.

Therefore, in the fuel injection device 10 according to the present embodiment, it is possible to specify which of the injector 30 and the high-pressure pump 16 has a failure.
(Other embodiments)
In the above-described embodiment, the present invention is applied to a fuel injection device for a vehicle diesel engine, but the application of the present invention is not limited to this.

  Moreover, in the above-mentioned embodiment, although the pressure sensor 22 was arrange | positioned at the entrance side of the common rail 20, this invention is not limited to this, As long as it is the high voltage | pressure path | route L1, the pressure sensor 22 is provided in any site | part. It may be arranged.

  Further, in the above-described embodiment, when an abnormality is detected, a warning is performed by turning on a warning lamp provided on the instrument panel of the vehicle, but the present invention is not limited to this, for example, A warning may be performed by voice.

  Further, the present invention is not limited to the above-described embodiment as long as it matches the gist of the invention described in the claims.

10 ... Fuel injection device, 12 ... Fuel tank, 14 ... Feed pump,
16 ... High pressure pump, 16A ... Check valve, 18 ... Flow control valve, 20 ... Common rail,
22 ... pressure sensor, 24 ... pressure reducing valve, 28 ... rotational speed sensor,
30 ... Injector, 50 ... Engine.

Claims (5)

A fuel injection device for supplying fuel to an internal combustion engine,
A high-pressure pump that pressurizes and supplies fuel stored in a fuel tank;
A common rail for stocking the high-pressure fuel supplied from the high-pressure pump;
An injector for injecting the high-pressure fuel stored in the common rail into the internal combustion engine;
A pressure sensor for detecting a pressure in a high pressure path from the high pressure pump to the injector through the common rail;
Pressure drop detection for detecting a pressure drop amount in the high pressure circuit based on a pressure detected by the pressure sensor when the fuel injection by the injector is changed to a state where fuel injection by the injector is stopped. Means,
A fuel injection device comprising: a determination unit that determines whether or not a pressure drop amount detected by the pressure drop detection unit is larger than a predetermined drop amount. A pressure reducing valve for opening and closing a circuit for communicating the high-pressure circuit and the fuel tank side;
The fuel injection device according to claim 1, further comprising: a valve closing unit that closes the pressure reducing valve when the pressure drop amount is detected. Flow control means for adjusting the amount of fuel supplied from the high-pressure pump within a predetermined adjustment range so that the pressure in the common rail becomes a control target pressure,
The pressure drop detecting means detects the pressure drop amount when the pressure in the common rail cannot be raised to the control target pressure by the adjustment within the adjustment range by the flow control means. The fuel injection device according to claim 1, wherein the fuel injection device is a fuel injection device.   The pressure drop detecting means detects the amount of pressure drop when the detected pressure when the fuel injection by the injector is stopped is equal to or higher than a predetermined pressure. The fuel injection device according to item.   5. The fuel injection device according to claim 1, further comprising a warning unit that issues a warning when the determination unit determines that the pressure drop amount is larger than the predetermined drop amount. 6. .

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