JP2007327404A - Common rail type fuel injection device - Google Patents

Common rail type fuel injection device Download PDF

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Publication number
JP2007327404A
JP2007327404A JP2006158764A JP2006158764A JP2007327404A JP 2007327404 A JP2007327404 A JP 2007327404A JP 2006158764 A JP2006158764 A JP 2006158764A JP 2006158764 A JP2006158764 A JP 2006158764A JP 2007327404 A JP2007327404 A JP 2007327404A
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fuel
pressure
common rail
valve
injection device
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Japanese (ja)
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Mamoru Oki
守 沖
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Denso Corp
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Denso Corp
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Priority to JP2006158764A priority Critical patent/JP2007327404A/en
Priority to DE200710000311 priority patent/DE102007000311A1/en
Publication of JP2007327404A publication Critical patent/JP2007327404A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20—Varying fuel delivery in quantity or timing
    • F02M59/36—Varying fuel delivery in quantity or timing by variably-timed valves controlling fuel passages to pumping elements or overflow passages
    • F02M59/366—Valves being actuated electrically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/3082—Control of electrical fuel pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • F02D41/3836—Controlling the fuel pressure
    • F02D41/3845—Controlling the fuel pressure by controlling the flow into the common rail, e.g. the amount of fuel pumped
    • F02D41/3854—Controlling the fuel pressure by controlling the flow into the common rail, e.g. the amount of fuel pumped with elements in the low pressure part, e.g. low pressure pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
    • F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D2041/228—Warning displays
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/31—Control of the fuel pressure

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Fuel-Injection Apparatus (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a common rail type fuel injection device having a suitable measures against abnormally high pressure and capable of making the measures in abnormally high pressure common among systems. <P>SOLUTION: A fuel tank 10 and a fuel pump 14 are connected through a low pressure fuel pipe 12. The low pressure fuel pipe 12 is provided with a fuel filter 13 and a fuel restricting valve 32. Fuel in the fuel tank 10 is sucked up by the fuel pump 14 through the low pressure fuel pipe 12, is compressed in the fuel pump 14 and is pressure-fed to a common rail 16. The fuel pressure-fed from the fuel pump 14 is stored in a high pressure condition in the common rail 16 and the high pressure fuel is supplied to the fuel injection valve 20 through a high pressure pipe 18. The fuel restricting valve 32 is driven into a closed state when fuel pressure in the common rail 16 is abnormally high. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、コモンレール式燃料噴射装置に関するものである。   The present invention relates to a common rail fuel injection device.

この種の燃料噴射装置としては、ディーゼル機関の各気筒の燃料噴射弁に高圧の燃料を供給するコモンレールを備えるものが周知である。このコモンレール式のディーゼル機関によれば、燃料噴射弁を介して噴射される燃料の圧力、いわゆる噴射圧を所望の噴射圧に制御することができる。   As this type of fuel injection device, one having a common rail for supplying high-pressure fuel to a fuel injection valve of each cylinder of a diesel engine is well known. According to this common rail type diesel engine, the pressure of the fuel injected through the fuel injection valve, so-called injection pressure, can be controlled to a desired injection pressure.

一方、コモンレール内の燃圧を制御する燃圧制御装置は、燃料ポンプの備える吸入調量弁（流量調整弁）を操作することで、燃圧の検出値を目標値にフィードバック制御する。ただし、吸入調量弁においては、弁体摺動部に異物が挟まれる、いわゆる噛み込み故障や駆動電流入力用のワイヤハーネスの断線故障などにより作動異常が生じることが考えられる。これにより、燃料ポンプからコモンレールに高圧燃料が過剰圧送され、コモンレール内の燃圧が異常高圧状態になるおそれがあった。この異常高圧により、コモンレールシステムを構成する部品（特に、高圧側のインジェクタ、コモンレール、センサ、バルブ等）の破損、及びこの破損による燃料漏れが発生するおそれがあり、これを防止する必要があった。   On the other hand, a fuel pressure control device that controls the fuel pressure in the common rail performs feedback control of the detected value of the fuel pressure to the target value by operating an intake metering valve (flow rate adjusting valve) provided in the fuel pump. However, in the intake metering valve, it is conceivable that an abnormal operation may occur due to a so-called biting failure or a disconnection failure of the wire harness for driving current input, in which foreign matter is caught in the valve body sliding portion. As a result, high-pressure fuel is excessively pumped from the fuel pump to the common rail, and the fuel pressure in the common rail may become an abnormally high pressure state. Due to this abnormally high pressure, there is a risk of damage to components (particularly high-pressure injectors, common rails, sensors, valves, etc.) constituting the common rail system, and fuel leakage due to this damage, which must be prevented. .

異常高圧状態にあるコモンレール内の燃圧を低減する方法としては、例えば下記特許文献１に見られるように、コモンレール内の高圧燃料をプレッシャリミッタにより排出させる方法がある。この場合は、燃圧がコモンレールの耐圧に基づき設定した所定圧（限界圧）を超えるとプレッシャリミッタが機械的に開弁し、それに伴いコモンレール内の燃料が排出される。また、別の燃圧低減方法として、燃圧調整機能を有する減圧弁を用いる方法もある。この方法では、圧力センサにより異常高圧を検知した場合、減圧弁を連続的に駆動し続けてリターン経路を開放することによりコモンレール内の燃料が排出される。   As a method for reducing the fuel pressure in the common rail in an abnormally high pressure state, for example, as can be seen in Patent Document 1 below, there is a method in which the high pressure fuel in the common rail is discharged by a pressure limiter. In this case, when the fuel pressure exceeds a predetermined pressure (limit pressure) set based on the pressure resistance of the common rail, the pressure limiter is mechanically opened, and the fuel in the common rail is discharged accordingly. As another fuel pressure reduction method, there is a method using a pressure reducing valve having a fuel pressure adjusting function. In this method, when an abnormal high pressure is detected by the pressure sensor, the fuel in the common rail is discharged by continuously driving the pressure reducing valve to open the return path.

しかしながら、上記したプレッシャリミッタや減圧弁を用いた燃圧低減方法では、異常高圧時における減圧能力をコモンレールシステムごとに作り分ける必要があり、これらの設計と信頼性の確保が困難になるといった不都合があった。すなわち、プレッシャリミッタではその限界圧をシステムごとの耐圧に応じて作り分ける必要があった。また、減圧弁では燃料の排出能力を異常高圧状態に対応できる能力（高耐圧仕様）にする必要があり、この結果、燃圧の制御分解能が低下して燃圧調整機能が損なわれていた。
特開２００４−１５６５５８号公報 However, the fuel pressure reduction method using the pressure limiter and the pressure reducing valve described above requires that the pressure reducing capability at abnormally high pressures be created for each common rail system, which makes it difficult to ensure their design and reliability. It was. That is, in the pressure limiter, it is necessary to make the limit pressure according to the pressure resistance of each system. In addition, the pressure reducing valve needs to have a fuel discharge capability (high pressure resistance specification) that can cope with an abnormally high pressure state. As a result, the control resolution of the fuel pressure is lowered and the fuel pressure adjustment function is impaired.
JP 2004-156558 A

本発明の目的は、コモンレール式燃料噴射装置において適正な異常高圧対策を講じ、しかもシステム間で異常高圧時の対策を共通化できる装置を提供することにある。   An object of the present invention is to provide an apparatus that can take appropriate measures against abnormal high pressure in a common rail fuel injection device and can share measures for abnormal high pressure among systems.

本発明におけるコモンレール式燃料噴射装置は、燃料吐出量を調整するための流量調整弁を有し低圧燃料経路から供給される燃料を高圧化して吐出する燃料ポンプと、燃料ポンプから加圧供給される高圧燃料を蓄えるコモンレールと、コモンレールから供給される高圧燃料を内燃機関へ噴射供給する燃料噴射弁とを備えている。このコモンレール式燃料噴射装置では、流量調整弁の作動異常などにより燃料ポンプからコモンレールに高圧燃料が過剰圧送されると、コモンレール内の燃圧が異常高圧状態になる。その対策として、請求項１に記載の発明では、低圧燃料経路上に流量制限有りの状態と無しの状態とが切替えられる燃料制限部材を設けた。そして、燃圧が異常高圧となったか否かを判定し、同燃圧が異常高圧であると判定された場合に燃料制限部材を流量制限有りの状態に操作するよう制御を行う構成とした。   The common rail fuel injection device according to the present invention has a flow rate adjusting valve for adjusting the fuel discharge amount, a fuel pump for increasing the pressure of the fuel supplied from the low-pressure fuel path, and a pressure supply from the fuel pump. A common rail that stores high-pressure fuel and a fuel injection valve that injects high-pressure fuel supplied from the common rail to the internal combustion engine are provided. In this common rail type fuel injection device, when high pressure fuel is excessively pumped from the fuel pump to the common rail due to abnormal operation of the flow rate adjustment valve, the fuel pressure in the common rail becomes an abnormally high pressure state. As a countermeasure, in the first aspect of the present invention, a fuel limiting member is provided on the low-pressure fuel path to switch between a state with and without a flow rate restriction. Then, it is determined whether or not the fuel pressure has become an abnormally high pressure, and when it is determined that the fuel pressure is an abnormally high pressure, control is performed so that the fuel limiting member is operated in a state in which the flow rate is limited.

本構成によれば、燃料制限部材により燃料流量が制限されることにより、コモンレールへの燃料圧送量が減じられ、燃圧を低減できる。これにより、異常高圧状態が抑制され、コモンレールシステムを構成する部品を保護できる。また、コモンレール内の高圧燃料を排出するためのプレッシャリミッタや減圧弁を有する従来技術ではシステムごとの耐圧に応じた設計を要していたが、本構成では低圧燃料経路に燃料制限部材を設けたため、システムごとの耐圧設計が不要となる。従って、耐圧の異なるシステム間においても共通の対策部品を用いて異常高圧対策を実施することができる。以上により、適正な異常高圧対策を講じつつ、システム間で異常高圧時の対策を共通化できる。   According to this configuration, the fuel flow rate is restricted by the fuel restriction member, so that the amount of fuel pumped to the common rail is reduced, and the fuel pressure can be reduced. Thereby, an abnormally high pressure state is suppressed, and the components constituting the common rail system can be protected. In addition, in the prior art having a pressure limiter and a pressure reducing valve for discharging the high-pressure fuel in the common rail, a design corresponding to the pressure resistance for each system is required, but in this configuration, a fuel limiting member is provided in the low-pressure fuel path. Therefore, the withstand voltage design for each system becomes unnecessary. Therefore, it is possible to implement countermeasures against abnormally high pressure using common countermeasure parts even between systems with different breakdown voltages. As described above, measures for abnormally high pressure can be made common among systems while taking appropriate measures for abnormally high pressure.

請求項２に記載の発明では、燃料制限部材は、その弁開度が全開となる開状態と、同弁解度が微小開度となる閉状態とで切り替え操作される燃料制限弁である。この場合、異常高圧時において、同燃料制限弁が微小開度とされることにより、燃料ポンプに対する燃料供給が微小量に制限されつつ継続される。これにより、燃料噴射弁による噴射を継続できるので異常高圧対策を行いつつ退避走行が可能となる。   According to a second aspect of the present invention, the fuel limiting member is a fuel limiting valve that is switched between an open state in which the valve opening degree is fully open and a closed state in which the valve opening degree is a minute opening degree. In this case, at the time of abnormally high pressure, the fuel limit valve is set to a minute opening, so that fuel supply to the fuel pump is continued while being limited to a minute amount. As a result, the injection by the fuel injection valve can be continued, and retreat traveling is possible while taking measures against abnormal high pressure.

請求項３に記載の発明では、異常高圧時に燃料制限弁が微小開度とされた状態で、流量調整弁が所定開度となるよう制御信号が出力される。この場合、流量調整弁に対する制御信号の出力により、燃料制限弁により流量制限された燃料が必要以上に減少されることの抑制が可能となる。これにより、異常高圧が燃料制限弁の作動異常以外の要因である場合等において、燃料ポンプに対する燃料供給を継続できるので異常高圧対策を行いつつ退避走行が可能となる。   In a third aspect of the present invention, the control signal is output so that the flow rate regulating valve has a predetermined opening degree in a state where the fuel limit valve has a small opening degree at an abnormally high pressure. In this case, the output of the control signal to the flow rate regulating valve can suppress the fuel whose flow rate is limited by the fuel limiting valve from being reduced more than necessary. As a result, when the abnormally high pressure is a factor other than the abnormal operation of the fuel limit valve, the fuel supply to the fuel pump can be continued.

請求項４に記載の発明では、コモンレール内における実燃圧（実レール圧）を検出し、検出した実レール圧がコモンレールの耐圧に基づき設定した所定圧以上となる場合に異常高圧であると判定するため、異常高圧時の減圧制御を耐圧基準として実施できる。   In the invention according to claim 4, the actual fuel pressure (actual rail pressure) in the common rail is detected, and when the detected actual rail pressure is equal to or higher than a predetermined pressure set based on the withstand pressure of the common rail, it is determined that the pressure is abnormally high. Therefore, the pressure reduction control at the time of abnormally high pressure can be carried out with the pressure resistance reference.

請求項５に記載の発明では、燃圧フィードバック制御の実施に際し、コモンレール内の実レール圧と目標値（目標燃圧）との偏差が所定値以上となり且つその状態が所定期間以上継続する場合に異常高圧であると判定する。つまり、燃圧偏差が異常となる場合には、燃料圧送系統で何らかの異常が発生して燃圧がコモンレールの耐圧に達する蓋然性が高いと考えられる。この点、上記構成によれば、燃圧が耐圧に達する前の時点で同燃圧が減圧側に制御され、異常高圧にいち早く対処できる。   In the invention according to claim 5, when the fuel pressure feedback control is performed, an abnormally high pressure is detected when the deviation between the actual rail pressure in the common rail and the target value (target fuel pressure) exceeds a predetermined value and the state continues for a predetermined period or longer. It is determined that That is, when the fuel pressure deviation becomes abnormal, it is considered that there is a high probability that some abnormality occurs in the fuel pumping system and the fuel pressure reaches the common rail pressure resistance. In this regard, according to the above-described configuration, the fuel pressure is controlled to the pressure reducing side before the fuel pressure reaches the pressure resistance, and an abnormal high pressure can be dealt with quickly.

以下、本発明を具体化した一実施の形態を図面に従って説明する。本実施の形態は、コモンレール式ディーゼル機関の燃料噴射装置に具体化した事例を説明する。   DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the present embodiment, a case in which the fuel injection device is embodied in a common rail diesel engine will be described.

図１に、エンジンシステムの全体構成を示す。図示されるように、燃料タンク１０と燃料ポンプ１４とは低圧燃料配管１２により接続されており、その低圧燃料配管１２には燃料フィルタ１３が設けられている。燃料タンク１０内の燃料は、低圧燃料配管１２を介し燃料ポンプ１４により汲み上げられ、燃料ポンプ１４にて圧縮された後コモンレール１６に圧送される。コモンレール１６では、燃料ポンプ１４から圧送された燃料が高圧状態で蓄えられ、この高圧燃料が高圧燃料配管１８を介して燃料噴射弁２０に供給される。   FIG. 1 shows the overall configuration of the engine system. As illustrated, the fuel tank 10 and the fuel pump 14 are connected by a low-pressure fuel pipe 12, and a fuel filter 13 is provided in the low-pressure fuel pipe 12. The fuel in the fuel tank 10 is pumped up by the fuel pump 14 through the low-pressure fuel pipe 12, compressed by the fuel pump 14, and then pumped to the common rail 16. In the common rail 16, the fuel pumped from the fuel pump 14 is stored in a high pressure state, and this high pressure fuel is supplied to the fuel injection valve 20 via the high pressure fuel pipe 18.

コモンレール１６には、電磁駆動式の減圧弁３４が設けられている。減圧弁３４は開状態（開度１００％）又は閉状態（開度０％）の何れかの状態に操作され、その開弁に伴いコモンレール１６内の高圧燃料がリリーフ配管３６を経由して燃料タンク１０へと排出される。これにより、コモンレール１６内の圧力が減圧されるようになっている。   The common rail 16 is provided with an electromagnetically driven pressure reducing valve 34. The pressure reducing valve 34 is operated in either an open state (opening degree 100%) or a closed state (opening degree 0%), and the high-pressure fuel in the common rail 16 is supplied to the fuel via the relief pipe 36 as the valve is opened. It is discharged to the tank 10. As a result, the pressure in the common rail 16 is reduced.

上記エンジンシステムは、コモンレール１６内の燃圧を検出する燃圧センサ２２や、ディーゼル機関のクランク軸２４の回転角度を検出するクランク角センサ２６等、ディーゼル機関の運転状態を検出する各種センサを備えている。更に、エンジンシステムは、ユーザによる加速要求の指示に用いられるアクセルペダルについて、その操作量を検出するアクセルセンサ２８を備えている。   The engine system includes various sensors that detect the operating state of the diesel engine, such as a fuel pressure sensor 22 that detects the fuel pressure in the common rail 16 and a crank angle sensor 26 that detects the rotation angle of the crankshaft 24 of the diesel engine. . The engine system further includes an accelerator sensor 28 that detects an operation amount of an accelerator pedal that is used to instruct an acceleration request by a user.

制御装置３０は、ＥＣＵ（エンジン制御ユニット）とＥＤＵ（駆動ユニット）とから構成され、上記各種センサの検出結果を取り込みコモンレール１６内の燃圧をフィードバック制御する。つまり、エンジン回転速度やアクセル開度等に基づいて目標燃圧を算出し、燃圧センサ２２によって検出されるコモンレール１６内の燃圧（実レール圧）が同目標燃圧に一致するよう、燃料ポンプ１４の燃料吐出量を調整することで燃圧フィードバック制御を実施する。また、車両の減速時など燃圧低減時には、減圧弁３４を開弁駆動することによって燃圧の減圧制御を実施する。   The control device 30 includes an ECU (engine control unit) and an EDU (drive unit), takes in the detection results of the various sensors, and feedback-controls the fuel pressure in the common rail 16. That is, the target fuel pressure is calculated based on the engine speed, the accelerator opening, etc., and the fuel pressure of the fuel pump 14 is adjusted so that the fuel pressure in the common rail 16 (actual rail pressure) detected by the fuel pressure sensor 22 matches the target fuel pressure. Fuel pressure feedback control is performed by adjusting the discharge amount. Further, when the fuel pressure is reduced such as when the vehicle is decelerated, the pressure reducing valve 34 is driven to open, thereby reducing the fuel pressure.

図２に、燃料ポンプ１４の構成を示す。燃料ポンプ１４は、フィードポンプ４０によって燃料タンク１０から汲み上げた燃料を高圧ポンプ５０にて加圧して吐出するものであり、且つ高圧ポンプ５０の燃料吐出量を吸入調量弁６０により調節するものである。   FIG. 2 shows the configuration of the fuel pump 14. The fuel pump 14 pressurizes and discharges the fuel pumped from the fuel tank 10 by the feed pump 40 by the high-pressure pump 50, and adjusts the fuel discharge amount of the high-pressure pump 50 by the intake metering valve 60. is there.

フィードポンプ４０は、駆動軸４１の回転により駆動されるトロコイドポンプであり、燃料タンク１０の燃料を入口４２から吸引して高圧ポンプ５０へ送る低圧供給ポンプとして機能する。なお、駆動軸４１は、ディーゼル機関のクランク軸２４の回転に伴い回転駆動される。   The feed pump 40 is a trochoid pump that is driven by the rotation of the drive shaft 41, and functions as a low-pressure supply pump that sucks the fuel in the fuel tank 10 from the inlet 42 and sends the fuel to the high-pressure pump 50. The drive shaft 41 is driven to rotate as the crankshaft 24 of the diesel engine rotates.

高圧ポンプ５０は、吸入調量弁６０によって調量された燃料を加圧して外部へ吐出するプランジャポンプである。高圧ポンプ５０は、駆動軸４１の回転により往復駆動されるプランジャ５１と、このプランジャ５１の往復動によって容積が変化する加圧室５２と、加圧室５２とフィードポンプ４０側とを連通及び遮断する吸入弁５３と、加圧室５２と上記コモンレール１６側とを連通及び遮断する吐出弁５４とを備える。   The high-pressure pump 50 is a plunger pump that pressurizes the fuel metered by the suction metering valve 60 and discharges the fuel to the outside. The high-pressure pump 50 communicates and blocks the plunger 51 that is reciprocated by the rotation of the drive shaft 41, the pressurizing chamber 52 whose volume is changed by the reciprocating motion of the plunger 51, and the pressurizing chamber 52 and the feed pump 40 side. And a discharge valve 54 that communicates and blocks the pressurizing chamber 52 and the common rail 16 side.

プランジャ５１は、駆動軸４１のエキセンカム５５の周囲に装着されたカムリング５６にスプリング５７によって押し付けられており、駆動軸４１が回転するとカムリング５６の偏心動作に伴ってプランジャ５１が圧送上死点から圧送下死点までの間を往復動する。ここで、プランジャ５１の下降により加圧室５２内の圧力が低下すると、吐出弁５４が閉弁するとともに吸入弁５３が開弁する。これにより、吸入調量弁６０を介してフィードポンプ４０から加圧室５２内に燃料が供給される。逆に、プランジャ５１の上昇により加圧室５２内の圧力が上昇すると、吸入弁５３が閉弁する。そして、加圧室５２内の圧力が所定圧力に達すると吐出弁５４が開弁して加圧室５２内で加圧された高圧燃料が上記コモンレール１６へ向けて供給される。   The plunger 51 is pressed against a cam ring 56 mounted around the eccentric cam 55 of the drive shaft 41 by a spring 57. When the drive shaft 41 rotates, the plunger 51 is pumped from the top dead center of the pump pump with the eccentric operation of the cam ring 56. Reciprocates between bottom dead center. Here, when the pressure in the pressurizing chamber 52 decreases due to the lowering of the plunger 51, the discharge valve 54 is closed and the suction valve 53 is opened. As a result, fuel is supplied from the feed pump 40 into the pressurizing chamber 52 via the intake metering valve 60. Conversely, when the pressure in the pressurizing chamber 52 rises due to the rise of the plunger 51, the suction valve 53 is closed. When the pressure in the pressurizing chamber 52 reaches a predetermined pressure, the discharge valve 54 is opened, and the high-pressure fuel pressurized in the pressurizing chamber 52 is supplied toward the common rail 16.

吸入調量弁６０において電磁ソレノイド６８に対する通電量を変化させることにより、燃料通路４４を介してフィードポンプ４０から高圧ポンプ５０への燃料吸入量が調節される。電磁ソレノイド６８に対する通電は、制御装置３０からワイヤハーネス（図示略）及びコネクタ６９を介して電磁ソレノイド６８へと至る経路で行われる。なお、本実施の形態におけるソレノイド６８に対する通電は、所定の周波数（例えば「２５０Ｈｚ」）の駆動信号の投入として行われ、この駆動信号のデューティ比により指令電流値が調節される。   By changing the energization amount to the electromagnetic solenoid 68 in the intake metering valve 60, the fuel intake amount from the feed pump 40 to the high pressure pump 50 via the fuel passage 44 is adjusted. Energization of the electromagnetic solenoid 68 is performed through a path from the control device 30 to the electromagnetic solenoid 68 via the wire harness (not shown) and the connector 69. Note that energization of the solenoid 68 in the present embodiment is performed by inputting a drive signal having a predetermined frequency (for example, “250 Hz”), and the command current value is adjusted by the duty ratio of the drive signal.

吸入調量弁６０を構成するシリンダ６１内には、その軸方向に変位可能なスプール６２が収容されている。スプール６２はスプリング６６の付勢力により軸方向の一方に押されている。電磁ソレノイド６８が通電されると、ソレノイド６８に生じる磁界によりスプール６２がスプリング６６の付勢力に抗して変位し、フィードポンプ４０から高圧ポンプ５０へと燃料が流出する際の流路面積（吸入調量弁６０の開度）が変更される。   A spool 62 that is displaceable in the axial direction is accommodated in a cylinder 61 constituting the intake metering valve 60. The spool 62 is pushed in one axial direction by the urging force of the spring 66. When the electromagnetic solenoid 68 is energized, the spool 62 is displaced against the urging force of the spring 66 by the magnetic field generated in the solenoid 68, and the flow path area (suction) when fuel flows from the feed pump 40 to the high-pressure pump 50. The opening degree of the metering valve 60 is changed.

吸入調量弁６０をノーマリオープンタイプ（常開型）とする場合、吸入調量弁６０の開度はソレノイド６８に対する指令電流値が大きいほど減少する。ここで、吸入調量弁６０から高圧ポンプ５０への燃料吸入量の最大値は高圧ポンプ５０の最大吐出量よりも大きい。すなわち、指令電流値を徐々に下げていくと、その下降途中で高圧ポンプ５０の最大吐出量に達して以降の吐出量は一定となる。また、吸入調量弁６０をノーマリクローズタイプ（常閉型）とする場合、吸入調量弁６０の開度はソレノイド６８に対する指令電流値が大きいほど上昇する。従って、指令電流値を徐々に上げていくと、その上昇途中で高圧ポンプ５０の最大吐出量に達して、以降の吐出量は一定となる。   When the intake metering valve 60 is of a normally open type (normally open type), the opening degree of the intake metering valve 60 decreases as the command current value for the solenoid 68 increases. Here, the maximum value of the fuel intake amount from the intake metering valve 60 to the high pressure pump 50 is larger than the maximum discharge amount of the high pressure pump 50. That is, when the command current value is gradually decreased, the maximum discharge amount of the high-pressure pump 50 is reached in the middle of the decrease, and the discharge amount thereafter becomes constant. Further, when the intake metering valve 60 is of a normally closed type (normally closed type), the opening degree of the intake metering valve 60 increases as the command current value for the solenoid 68 increases. Therefore, when the command current value is gradually increased, the maximum discharge amount of the high-pressure pump 50 is reached in the middle of the increase, and the subsequent discharge amount becomes constant.

指令電流値は、制御装置３０により以下の手順で算出される。まず、コモンレール１６の実レール圧と目標燃圧との差圧に基づいて高圧ポンプ５０（燃料ポンプ１４）の目標吐出量が算出される。この目標吐出量に応じて、高圧ポンプ５０の加圧室５２に供給される燃料の流量が算出される。そして、この流量を実現する吸入調量弁６０の開度から指令電流値が算出される。   The command current value is calculated by the control device 30 according to the following procedure. First, the target discharge amount of the high-pressure pump 50 (fuel pump 14) is calculated based on the differential pressure between the actual rail pressure of the common rail 16 and the target fuel pressure. The flow rate of the fuel supplied to the pressurizing chamber 52 of the high-pressure pump 50 is calculated according to the target discharge amount. Then, a command current value is calculated from the opening of the intake metering valve 60 that realizes this flow rate.

ところで、吸入調量弁６０では、シリンダ６１の内周とスプール６２の外周との間に異物が挟み込まれるいわゆる噛み込みが生じることがある。この場合、吸入調量弁６０の開度制御ができなくなり、弁の開度が全開若しくは全開に近い状態で制御不能に陥る可能性がある。また、吸入調量弁６０のコネクタ６９に接続されたワイヤハーネスが、何らかの原因によりコネクタ類との接続不良や断線を起こすことがあり、この場合には吸入調量弁６０が制御不能となる。これら吸入調量弁６０の故障により、高圧ポンプ５０から過剰に燃料が吐出され、コモンレール１６内の燃圧が異常高圧状態になるおそれがある。   By the way, in the intake metering valve 60, so-called biting may occur in which foreign matter is sandwiched between the inner periphery of the cylinder 61 and the outer periphery of the spool 62. In this case, the opening degree of the intake metering valve 60 cannot be controlled, and there is a possibility that the control becomes impossible when the opening degree of the valve is fully open or close to full open. In addition, the wire harness connected to the connector 69 of the intake metering valve 60 may cause a connection failure or disconnection with the connectors for some reason. In this case, the suction metering valve 60 becomes uncontrollable. Due to the failure of the intake metering valve 60, excessive fuel is discharged from the high-pressure pump 50, and the fuel pressure in the common rail 16 may become an abnormally high pressure state.

本実施の形態では、異常高圧の対策として低圧燃料配管１２に燃料制限弁３２を設け、制御装置３０からの指令に基づいて燃料制限弁３２を開閉させるようにしている。燃料制限弁３２はノーマリオープンタイプであり、制御装置３０からオン信号が出力された場合にのみ閉状態に駆動される。燃料制限弁３２における閉状態とは燃料の流量が制限されている状態であり、その流路面積は微小である。コモンレール１６内の燃圧が正常である場合には、燃料制限弁３２は開状態（開度１００％）に維持される。また、燃圧が異常高圧状態である場合には燃料制限弁３２が閉状態に駆動され高圧ポンプ５０に汲み上げられる燃料の流量が制限される。それにより、燃料ポンプ１４からコモンレール１６への燃料吐出量が減じられ燃圧が低減される。   In the present embodiment, as a countermeasure against abnormally high pressure, a fuel limiting valve 32 is provided in the low pressure fuel pipe 12, and the fuel limiting valve 32 is opened and closed based on a command from the control device 30. The fuel limiting valve 32 is a normally open type, and is driven to a closed state only when an ON signal is output from the control device 30. The closed state of the fuel restriction valve 32 is a state where the flow rate of the fuel is restricted, and the flow passage area is very small. When the fuel pressure in the common rail 16 is normal, the fuel limit valve 32 is maintained in the open state (opening degree 100%). In addition, when the fuel pressure is in an abnormally high pressure state, the fuel restriction valve 32 is driven to the closed state, and the flow rate of the fuel pumped up to the high pressure pump 50 is restricted. Thereby, the amount of fuel discharged from the fuel pump 14 to the common rail 16 is reduced, and the fuel pressure is reduced.

ここで、異常高圧時には、燃料制限弁３２を閉状態としてコモンレール１６への燃料吐出量が減じられるが、燃料ポンプ１４の燃料吐出量は、車両を退避走行させる目的で継続走行させるのに必要な燃圧を確保できる流量とされるのが望ましい。この際、吸入調量弁６０を所定開度にさせるべく制御装置３０から制御信号が出力されることにより、異常高圧が吸入調量弁６０の故障以外の要因（燃料噴射弁２０や減圧弁３４の制御性の低下など）により生じる場合等に、燃料ポンプ１４に対する燃料供給が継続できる。   Here, at the time of abnormally high pressure, the fuel limit valve 32 is closed and the fuel discharge amount to the common rail 16 is reduced. However, the fuel discharge amount of the fuel pump 14 is necessary for continuous running for the purpose of retracting the vehicle. It is desirable that the flow rate be sufficient to ensure the fuel pressure. At this time, a control signal is output from the control device 30 to bring the intake metering valve 60 to a predetermined opening, so that the abnormal high pressure is caused by factors other than the failure of the intake metering valve 60 (the fuel injection valve 20 and the pressure reducing valve 34). The fuel supply to the fuel pump 14 can be continued, for example, when it occurs due to a decrease in controllability.

以下、コモンレール１６内の燃圧が異常高圧状態になる場合、燃料制限弁３２を閉状態に駆動して燃圧を低減しつつ退避走行へと移行するまでの処理を、図３に基づき説明する。図３に示す処理は、制御装置３０により例えば所定周期で繰り返し実行される。   Hereinafter, when the fuel pressure in the common rail 16 is in an abnormally high pressure state, a process until the fuel limit valve 32 is driven to the closed state and the fuel pressure is reduced to shift to the retreat travel will be described with reference to FIG. The process shown in FIG. 3 is repeatedly executed by the control device 30 at a predetermined cycle, for example.

この一連の処理は、運転者がイグニッションスイッチをオンした時点で起動される。まずステップＳ１０では故障履歴のフラグ（ＦＤＩＡＧ）を読み込む。故障無し（ＦＤＩＡＧ＝０）の場合は次のステップＳ１２の処理へと移る。故障有り（ＦＤＩＡＧ＝１）の場合には退避走行を行うべくステップＳ１８へ移る。   This series of processing is started when the driver turns on the ignition switch. First, in step S10, a failure history flag (FDIAG) is read. If there is no failure (FDIAG = 0), the process proceeds to the next step S12. If there is a failure (FDIAG = 1), the process proceeds to step S18 to perform evacuation travel.

ステップＳ１２では、各種センサの検出信号に基づいて算出されたディーゼル機関の運転状態を読み込むとともに、コモンレール１６の目標燃圧ＰＦＩＮを算出する。このとき、コモンレール１６内の実レール圧Ｐｃ、エンジン回転速度ＮＥ、アクセル開度ＡＣＣＰ等が読み込まれ、これらの値を基に目標燃圧ＰＦＩＮが算出される。   In step S12, the operation state of the diesel engine calculated based on the detection signals of various sensors is read, and the target fuel pressure PFIN of the common rail 16 is calculated. At this time, the actual rail pressure Pc in the common rail 16, the engine speed NE, the accelerator opening ACCP, and the like are read, and the target fuel pressure PFIN is calculated based on these values.

ステップＳ１４では、実レール圧Ｐｃが所定圧Ｐｍａｘ以上か否かを判定する。Ｐｍａｘは、コモンレール１６の耐圧に基づき算出される圧力限界値である。Ｐｃ≧Ｐｍａｘである場合には退避走行を行うべくステップＳ１８へ移る。Ｐｃ＜Ｐｍａｘである場合には、次のステップＳ１６へ移る。   In step S14, it is determined whether or not the actual rail pressure Pc is equal to or higher than a predetermined pressure Pmax. Pmax is a pressure limit value calculated based on the breakdown voltage of the common rail 16. If Pc ≧ Pmax, the process proceeds to step S18 to perform retreat travel. If Pc <Pmax, the process proceeds to the next step S16.

ステップＳ１６では、目標燃圧ＰＦＩＮに対する実レール圧Ｐｃの差圧ΔＰｃ（＝Ｐｃ−ＰＦＩＮ）が所定値Ｋ以上であり、且つその状態が期間Ｔ継続しているか否かを判定する。ここで、異常判定用の所定値Ｋ及び期間Ｔは、燃圧センサ２２から出力される電気信号のノイズ等による誤検出を防止できる値に設定される。上記異常ありと判定される場合にはステップＳ１８へと進み、異常無しと判定される場合には本処理を終了する。   In step S16, it is determined whether or not the differential pressure ΔPc (= Pc−PFIN) of the actual rail pressure Pc with respect to the target fuel pressure PFIN is equal to or greater than a predetermined value K and the state continues for the period T. Here, the predetermined value K and the period T for abnormality determination are set to values that can prevent erroneous detection due to noise or the like of the electrical signal output from the fuel pressure sensor 22. If it is determined that there is an abnormality, the process proceeds to step S18, and if it is determined that there is no abnormality, the process is terminated.

ステップＳ１８以降では、退避走行の処理を実行する。ステップＳ１８では、燃料制限弁３２を閉状態に駆動して、高圧ポンプ５０への燃料流量を制限する。   In step S18 and subsequent steps, a retreat travel process is executed. In step S18, the fuel restriction valve 32 is driven to the closed state to restrict the fuel flow rate to the high pressure pump 50.

ステップＳ２０では、吸入調量弁６０を所定開度にさせるべく制御装置３０から吸入調量弁６０への通電量が制御される。   In step S20, the energization amount from the control device 30 to the intake metering valve 60 is controlled so that the intake metering valve 60 has a predetermined opening.

ステップＳ２２では、上記の故障履歴のフラグ（ＦＤＩＡＧ）を１に設定するとともに、エンジン故障の警告灯を点灯させ、その後、本処理を終了する。   In step S22, the failure history flag (FDIAG) is set to 1, and an engine failure warning lamp is turned on. Thereafter, the present process is terminated.

ここで、上記の異常高圧に関する処理について図４のタイミングチャートに基づき更に説明する。図４では、上段よりコモンレール１６内の燃圧（実レール圧Ｐｃ及び目標燃圧ＰＦＩＮ）、燃料制限弁３２の開度、及び吸入調量弁６０の開度を示す。燃圧に関しては、目標燃圧ＰＦＩＮを一点鎖線で示し、実レール圧Ｐｃを実線で示す。   Here, the processing related to the abnormal high pressure will be further described based on the timing chart of FIG. 4, the fuel pressure (actual rail pressure Pc and target fuel pressure PFIN) in the common rail 16, the opening degree of the fuel limiting valve 32, and the opening degree of the intake metering valve 60 are shown from the upper stage. Regarding the fuel pressure, the target fuel pressure PFIN is indicated by a one-dot chain line, and the actual rail pressure Pc is indicated by a solid line.

図４において、タイミングｔ１以前は燃圧フィードバック制御により実レール圧Ｐｃが目標燃圧ＰＦＩＮ付近に収束した状態となっている。そして、吸入調量弁６０で異物噛み込み等が生じることにより実レール圧Ｐｃが上昇すると、タイミングｔ１で目標燃圧ＰＦＩＮに対する実レール圧Ｐｃの差圧ΔＰｃが所定値Ｋ以上となる。そして、タイミングｔ２で所定値Ｋ以上となる状態が期間Ｔ継続すると、燃料制限弁３２が閉状態に駆動されるとともに、吸入調量弁６０が全開状態に駆動されるよう制御装置３０から吸入調量弁６０への通電が停止される。   In FIG. 4, before the timing t1, the actual rail pressure Pc is converged to the vicinity of the target fuel pressure PFIN by the fuel pressure feedback control. Then, when the actual rail pressure Pc rises due to foreign matter biting or the like occurring at the intake metering valve 60, the differential pressure ΔPc of the actual rail pressure Pc with respect to the target fuel pressure PFIN becomes equal to or greater than the predetermined value K at timing t1. Then, when the state of being equal to or greater than the predetermined value K at the timing t2 continues for a period T, the fuel restriction valve 32 is driven to the closed state, and the intake metering valve 60 is driven to the fully open state so as to drive the intake control. The energization to the quantity valve 60 is stopped.

ここで、本図における吸入調量弁６０の開度は、制御装置３０による制御目標を示しているのみであり、実際の開度とは異なる可能性がある。つまり、吸入調量弁６０が故障していない場合は本図の通りとなるが、吸入調量弁６０が故障している場合は異なる挙動を示す可能性がある。   Here, the opening degree of the intake metering valve 60 in this drawing only indicates a control target by the control device 30 and may be different from the actual opening degree. That is, when the intake metering valve 60 is not broken, the flow is as shown in this figure. However, when the intake metering valve 60 is broken, there is a possibility of different behavior.

以上詳述した本実施の形態によれば、以下の優れた効果が得られる。   According to the embodiment described above in detail, the following excellent effects can be obtained.

低圧燃料配管１２に燃料制限弁３２を設け、コモンレール１６内の燃圧が異常高圧状態である場合に燃料制限弁３２を閉状態に駆動させることで燃料ポンプ１４への燃料供給量を制限した。これにより、燃料ポンプ１４からコモンレール１６への燃料圧送量が減じられ、燃圧を低減させられる。よって、異常高圧状態を抑制でき、システムを構成する部品（特に高圧燃料の圧送系統を構成するコモンレール１６、高圧燃料配管１８、燃料噴射弁２０、燃圧センサ２２、減圧弁３４等）を保護することができる。また、燃料制限弁３２を高圧側に設けた場合と比較して、システムごとの耐圧設計が不要となり、システム間で燃料制限弁３２の仕様を共通化できる。更に、減圧弁３４においては、異常高圧状態における排出能力を小さくできるので燃圧の制御分解能が向上し、その結果として燃圧調整機能を高めることができる。   A fuel limiting valve 32 is provided in the low-pressure fuel pipe 12, and the fuel supply amount to the fuel pump 14 is limited by driving the fuel limiting valve 32 in a closed state when the fuel pressure in the common rail 16 is in an abnormally high pressure state. Thereby, the fuel pumping amount from the fuel pump 14 to the common rail 16 is reduced, and the fuel pressure can be reduced. Therefore, the abnormal high pressure state can be suppressed, and the components constituting the system (particularly the common rail 16, the high pressure fuel pipe 18, the fuel injection valve 20, the fuel pressure sensor 22, the pressure reducing valve 34, etc. constituting the high pressure fuel pumping system) are protected. Can do. Further, as compared with the case where the fuel limit valve 32 is provided on the high pressure side, the pressure resistance design for each system becomes unnecessary, and the specifications of the fuel limit valve 32 can be made common between the systems. Further, since the discharge capacity in the abnormally high pressure state can be reduced in the pressure reducing valve 34, the control resolution of the fuel pressure is improved, and as a result, the fuel pressure adjusting function can be enhanced.

異常高圧の原因として主たるものは吸入調量弁６０の異常であると考えられ、その吸入調量弁６０の異常では低圧側の燃料制限が不可となる。この点、本実施の形態では、吸入調量弁６０の異常を原因とする異常高圧に好適に対処できる。   The main cause of the abnormal high pressure is considered to be an abnormality of the intake metering valve 60, and the abnormality of the intake metering valve 60 makes it impossible to restrict the fuel on the low pressure side. In this regard, in the present embodiment, it is possible to suitably cope with an abnormal high pressure caused by the abnormality of the intake metering valve 60.

異常高圧時においてもコモンレール１６への燃料圧送を継続できるよう、燃料制限弁３２の閉状態における開度を微小にした。これにより、燃料噴射弁２０による噴射を継続できるので異常高圧対策を行いつつ退避走行が可能となる。   The opening degree of the fuel limit valve 32 in the closed state is made minute so that the fuel pumping to the common rail 16 can be continued even at an abnormally high pressure. Thereby, since the injection by the fuel injection valve 20 can be continued, the retreat traveling can be performed while taking measures against abnormal high pressure.

異常高圧時に燃料制限弁３２が微小開度とされた状態で、吸入調量弁６０が所定開度となるよう、制御装置３０により制御信号が出力される構成にした。これにより、異常高圧が吸入調量弁６０の作動異常以外の要因により生じる場合等に燃料ポンプ１４に対する燃料供給が継続できる。   The control device 30 is configured to output a control signal so that the intake metering valve 60 has a predetermined opening degree while the fuel restriction valve 32 is at a very small opening degree during abnormally high pressure. Thereby, the fuel supply to the fuel pump 14 can be continued when an abnormal high pressure is caused by a factor other than the abnormal operation of the intake metering valve 60.

実レール圧が、コモンレール１６の耐圧に基づく圧力限界値（所定圧Ｐｍａｘ）を超えた時点で異常高圧であると判定した。本構成によれば、異常高圧時の減圧制御をコモンレール１６の耐圧を基準として実施できる。   When the actual rail pressure exceeded the pressure limit value (predetermined pressure Pmax) based on the pressure resistance of the common rail 16, it was determined that the pressure was abnormally high. According to this configuration, the pressure reduction control at the time of abnormally high pressure can be performed based on the breakdown voltage of the common rail 16.

目標燃圧に対する実レール圧の差圧ΔＰｃが所定値Ｋを超え、且つその状態が期間Ｔ継続している時点で異常高圧であると判定した。これにより、コモンレール１６内の燃圧が耐圧以上になることをいち早く回避できる。   When the differential pressure ΔPc of the actual rail pressure with respect to the target fuel pressure exceeds the predetermined value K and the state continues for the period T, it is determined that the pressure is abnormally high. Thereby, it can avoid quickly that the fuel pressure in the common rail 16 becomes more than a pressure | voltage resistance.

なお、本発明は上記実施の形態の記載内容に限定されず、例えば次のように実施しても良い。   In addition, this invention is not limited to the content of description of the said embodiment, For example, you may implement as follows.

上記実施の形態では、コモンレール１６には減圧弁３４を設けた構成としていたが、この減圧弁３４を設けない構成にしても良い。本構成においても、コモンレール１６内の燃圧を低減しつつ退避走行が可能である。   In the above embodiment, the common rail 16 is provided with the pressure reducing valve 34. However, the pressure reducing valve 34 may not be provided. Also in this configuration, the retreat traveling is possible while reducing the fuel pressure in the common rail 16.

上記実施の形態では、異常高圧状態になった場合にコモンレール１６内の燃圧を低減させるため燃料制限弁３２を閉状態に駆動していたが、同時に減圧弁３４を開状態に駆動しても良い。このように、コモンレールシステムの低圧側と高圧側の双方の減圧装置を作動させることにより、より迅速に燃圧を低減させることが可能である。   In the above embodiment, the fuel limiting valve 32 is driven to the closed state in order to reduce the fuel pressure in the common rail 16 when an abnormally high pressure state occurs, but at the same time, the pressure reducing valve 34 may be driven to the open state. . In this way, it is possible to reduce the fuel pressure more quickly by operating both the low pressure side and high pressure side pressure reducing devices of the common rail system.

上記実施の形態では、燃料制限部材として燃料ポンプ１４への燃料供給量を制限する燃料制限弁３２を設けたが、これを変更しても良い。例えば、低圧燃料配管１２を二系統に分岐させ、一方は比較的大きな流路面積（大流量）として他方は比較的小さな流路面積（微小流量）とする。また、燃料制限部材として、上記二つの流路を切り替える流路切り替え手段を設ける。そして、コモンレール１６内の燃圧が正常である場合には大流量側の配管をオープンにして微小流量側の配管を遮断するよう制御する。他方、燃圧が異常高圧である場合には、大流量側の配管を遮断して微小流量側の配管をオープンにするよう制御する。この構成によっても、上記実施の形態と同様の効果を得ることができる。   In the above embodiment, the fuel limiting valve 32 that limits the amount of fuel supplied to the fuel pump 14 is provided as the fuel limiting member, but this may be changed. For example, the low-pressure fuel pipe 12 is branched into two systems, one having a relatively large channel area (large flow rate) and the other having a relatively small channel area (micro flow rate). Further, a flow path switching means for switching the two flow paths is provided as a fuel limiting member. Then, when the fuel pressure in the common rail 16 is normal, control is performed so that the large flow rate side pipe is opened and the minute flow rate side pipe is shut off. On the other hand, when the fuel pressure is abnormally high, control is performed so that the pipe on the high flow rate side is shut off and the pipe on the minute flow rate side is opened. Also with this configuration, the same effect as in the above embodiment can be obtained.

発明の実施の形態におけるエンジンシステムの全体構成を示す図。The figure which shows the whole structure of the engine system in embodiment of invention. 同実施形態の燃料ポンプの断面構成を示す図。The figure which shows the cross-sectional structure of the fuel pump of the embodiment. 同実施形態にかかる異常高圧時の処理の手順を示すフローチャート。The flowchart which shows the procedure of the process at the time of the abnormal high pressure concerning the embodiment. 上記異常高圧時の処理の態様を示すタイムチャート。The time chart which shows the aspect of the process at the time of the said abnormal high pressure.

符号の説明Explanation of symbols

１０…燃料タンク、１２…低圧燃料配管（低圧燃料経路）、１３…燃料フィルタ、１４…燃料ポンプ、１６…コモンレール、１８…高圧燃料配管、２０…燃料噴射弁、２２…燃圧センサ、３０…制御装置、３２…燃料制限弁、３４…減圧弁、３６…リリーフ配管、６０…吸入調量弁（流量調整弁）。   DESCRIPTION OF SYMBOLS 10 ... Fuel tank, 12 ... Low pressure fuel piping (low pressure fuel path), 13 ... Fuel filter, 14 ... Fuel pump, 16 ... Common rail, 18 ... High pressure fuel piping, 20 ... Fuel injection valve, 22 ... Fuel pressure sensor, 30 ... Control Device: 32 ... Fuel limit valve, 34 ... Pressure reducing valve, 36 ... Relief piping, 60 ... Suction metering valve (flow rate regulating valve).

Claims (5)

燃料吐出量を調整するための流量調整弁を有し低圧燃料経路から供給される燃料を高圧化して吐出する燃料ポンプと、前記燃料ポンプから加圧供給される高圧燃料を蓄えるコモンレールと、前記コモンレールから供給される高圧燃料を内燃機関へ噴射供給する燃料噴射弁とを備えるコモンレール式燃料噴射装置において、
前記低圧燃料経路上に設けられ、流量制限有りの状態と無しの状態とが切替えられる燃料制限部材と、
前記コモンレール内の燃圧が異常高圧となったか否かを判定する異常判定手段と、
前記異常判定手段により異常高圧であると判定された場合に、前記燃料制限部材を流量制限有りの状態に操作する燃料制限制御手段とを備えたことを特徴とするコモンレール式燃料噴射装置。 A fuel pump having a flow rate adjusting valve for adjusting a fuel discharge amount and discharging a high-pressure fuel supplied from a low-pressure fuel path; a common rail for storing high-pressure fuel supplied under pressure from the fuel pump; and the common rail A common rail fuel injection device comprising a fuel injection valve that injects and supplies high-pressure fuel supplied from an internal combustion engine,
A fuel limiting member provided on the low-pressure fuel path and capable of switching between a state with and without a flow rate restriction;
An abnormality determining means for determining whether or not the fuel pressure in the common rail has become an abnormally high pressure;
A common rail fuel injection device comprising: a fuel restriction control means for operating the fuel restriction member to a state in which a flow restriction is present when the abnormality judgment means determines that the pressure is abnormally high. 前記燃料制限部材は、弁開度が全開となる開状態と、同弁開度が微小開度となる閉状態とで切り替え操作される燃料制限弁であり、
前記燃料制限制御手段は、前記異常判定手段により異常高圧であると判定された場合に、前記燃料制限弁を閉状態に操作することを特徴とする請求項１に記載のコモンレール式燃料噴射装置。 The fuel limiting member is a fuel limiting valve that is switched between an open state in which the valve opening is fully open and a closed state in which the valve opening is a minute opening;
2. The common rail fuel injection device according to claim 1, wherein the fuel restriction control means operates the fuel restriction valve in a closed state when the abnormality determination means determines that the pressure is abnormally high. 3. 前記異常判定手段により異常高圧であると判定された場合に、前記流量調整弁が所定開度となるよう制御信号を出力する手段を備えたことを特徴とする請求項２に記載のコモンレール式燃料噴射装置。   3. The common rail fuel according to claim 2, further comprising means for outputting a control signal so that the flow rate adjusting valve has a predetermined opening when the abnormality determining means determines that the pressure is abnormally high. Injection device. 前記コモンレール内における実燃圧を検出する燃圧検出手段を備え、前記異常判定手段は、前記検出した実燃圧が前記コモンレールの耐圧に基づき設定した所定圧以上となる場合に異常高圧であると判定することを特徴とする請求項１乃至３の何れかに記載のコモンレール式燃料噴射装置。   Fuel pressure detecting means for detecting an actual fuel pressure in the common rail is provided, and the abnormality determining means determines that the detected abnormal fuel pressure is abnormally high when the detected actual fuel pressure is equal to or higher than a predetermined pressure set based on the pressure resistance of the common rail. The common rail fuel injection device according to any one of claims 1 to 3. 前記内燃機関の運転状態等に基づいて前記コモンレール内の燃圧の目標値を設定し、その目標値と前記コモンレール内の実燃圧との偏差に基づいて燃圧フィードバック制御を実施するコモンレール式燃料噴射装置において、
前記異常判定手段は、前記コモンレール内における実燃圧と目標値との偏差が所定値以上となり、且つその状態が所定期間以上継続する場合に異常高圧であると判定することを特徴とする請求項１乃至４の何れかに記載のコモンレール式燃料噴射装置。 In a common rail fuel injection device that sets a target value of the fuel pressure in the common rail based on the operating state of the internal combustion engine, and performs fuel pressure feedback control based on a deviation between the target value and the actual fuel pressure in the common rail ,
2. The abnormality determination unit determines that the pressure is abnormally high when a deviation between an actual fuel pressure in the common rail and a target value is equal to or greater than a predetermined value and the state continues for a predetermined period or longer. The common rail type fuel injection device according to any one of claims 1 to 4.
JP2006158764A 2006-06-07 2006-06-07 Common rail type fuel injection device Pending JP2007327404A (en)

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