JP3416682B2 - Accumulator type fuel injection device - Google Patents
Accumulator type fuel injection deviceInfo
- Publication number
- JP3416682B2 JP3416682B2 JP33573598A JP33573598A JP3416682B2 JP 3416682 B2 JP3416682 B2 JP 3416682B2 JP 33573598 A JP33573598 A JP 33573598A JP 33573598 A JP33573598 A JP 33573598A JP 3416682 B2 JP3416682 B2 JP 3416682B2
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- fuel
- accumulator
- pressure accumulator
- control valve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Fuel-Injection Apparatus (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、蓄圧式燃料噴射装
置に関する。TECHNICAL FIELD The present invention relates to a pressure accumulation type fuel injection device.
【０００２】[0002]
【従来の技術】ディーゼルエンジンの燃料噴射装置とし
て、蓄圧器に蓄圧した高圧燃料をエンジンの各気筒に安
定に供給して低速域から高速域までの広い運転領域にお
いてエンジン性能を向上可能とする蓄圧式燃料噴射装置
（コモンレールシステム）がある。このような燃料噴射
装置を用いた場合でも、燃料噴射開始直後における燃料
噴射率が過大であると、燃焼の初期に急激な爆発燃焼が
行われ、エンジン騒音が増大するばかりでなく排気ガス
中の窒素酸化物（ＮＯｘ）が増大する。2. Description of the Related Art As a fuel injection device for a diesel engine, a pressure accumulator capable of stably supplying high pressure fuel accumulated in a pressure accumulator to each cylinder of the engine to improve engine performance in a wide operating range from a low speed range to a high speed range. There is a fuel injection system (common rail system). Even when such a fuel injection device is used, if the fuel injection rate immediately after the start of fuel injection is excessive, abrupt explosive combustion occurs at the early stage of combustion, which not only increases engine noise but also causes Nitrogen oxide (NOx) increases.
【０００３】このような不具合を解消するため、各回の
燃料噴射サイクルの初期段階において、低めの燃料噴射
率で燃料を噴射する蓄圧式燃料噴射装置が提案されてい
る。この提案に係わる燃料噴射装置は、例えば、低圧燃
料を貯溜する低圧蓄圧器と、高圧燃料を貯溜する高圧蓄
圧器と、低圧蓄圧器又は高圧蓄圧器をインジェクタ（燃
料噴射ノズル）に選択的に連通させて燃料噴射率を切り
換える切換弁と、インジェクタの圧力制御室と燃料タン
クとを連通・遮断して燃料噴射時期を制御する開閉弁と
を備えている。In order to solve such a problem, a pressure accumulating fuel injection system has been proposed which injects fuel at a low fuel injection rate in the initial stage of each fuel injection cycle. In the fuel injection device according to this proposal, for example, a low pressure accumulator that stores low pressure fuel, a high pressure accumulator that stores high pressure fuel, and a low pressure accumulator or a high pressure accumulator are selectively connected to an injector (fuel injection nozzle). A switching valve for switching the fuel injection rate is provided, and an on-off valve for controlling the fuel injection timing by connecting and blocking the pressure control chamber of the injector and the fuel tank.
【０００４】蓄圧器での燃圧形成に関して、例えば、エ
ンジンにより夫々駆動される低圧燃料ポンプ及び高圧燃
料ポンプを用いて低圧及び高圧の燃料を得るもの、或い
は、高圧燃料ポンプにより高圧燃料を得ると共に低圧蓄
圧器へ導入した高圧燃料を調圧して低圧燃料を得るもの
がある（例えば、特開平６−９３９３６）。また、高圧
蓄圧器の高圧燃料から低圧蓄圧器の低圧燃料を得るタイ
プの蓄圧式燃料噴射装置（例えば、ＷＯ９８／０９０６
８）では、例えば、各気筒のインジェクタに対応して設
置してある燃料噴射時期制御用の開閉弁を閉弁すると共
に燃料噴射率切換用の切換弁を低圧側へ切り換えること
により、インジェクタの燃料室（燃料溜まり）に低圧燃
料を満たすと共にインジェクタを閉弁状態に保持し、燃
料噴射開始時期が到来した時に開閉弁を開弁させてイン
ジェクタを開弁させて低圧燃料をノズルから噴射させて
低圧初期噴射（以下「低圧噴射」という）を行い、低圧
噴射期間が経過した時に切換弁を高圧側へ切り換え、高
圧蓄圧器からの高圧燃料をノズルから噴射させて高圧主
噴射（以下「高圧噴射」という）を行い、噴射終了時期
が到来すると切換弁を低圧側へ切り換えると共に開閉弁
を閉弁する。即ち、切換弁により低圧蓄圧器と高圧蓄圧
器を燃料噴射中に切り換えて燃料の噴射波形の制御を行
う。Regarding the fuel pressure formation in the pressure accumulator, for example, a low pressure fuel pump and a high pressure fuel pump are used to obtain low pressure and high pressure fuel, or a high pressure fuel pump is used to obtain high pressure fuel and low pressure fuel. There is one that obtains a low-pressure fuel by adjusting the pressure of the high-pressure fuel introduced into the pressure accumulator (for example, JP-A-6-93936). In addition, a pressure-accumulation fuel injection device of a type that obtains low-pressure fuel of a low-pressure accumulator from high-pressure fuel of a high-pressure accumulator (for example, WO98 / 0906).
In 8), for example, by closing the on-off valve for fuel injection timing control installed corresponding to the injector of each cylinder and switching the switching valve for switching the fuel injection rate to the low pressure side, The chamber (fuel pool) is filled with low-pressure fuel and the injector is kept closed. When the fuel injection start timing arrives, the on-off valve is opened and the injector is opened to inject low pressure fuel from the nozzle to inject low pressure fuel. Initial injection (hereinafter referred to as "low-pressure injection") is performed, and when the low-pressure injection period has elapsed, the switching valve is switched to the high-pressure side, and high-pressure fuel from the high-pressure accumulator is injected from the nozzle to generate high-pressure main injection (hereinafter "high-pressure injection"). When the injection end timing comes, the switching valve is switched to the low pressure side and the on-off valve is closed. That is, the switching valve switches the low pressure accumulator and the high pressure accumulator during fuel injection to control the fuel injection waveform.
【０００５】低圧蓄圧器では、前記切換弁が閉弁した後
当該切換弁とインジェクタの燃料室との間に溜まった高
圧燃料を調圧して低圧燃料を得る。即ち、低圧蓄圧器と
燃料タンクとの燃料通路に接続されている低圧蓄圧器の
圧力制御弁をデューティ制御して、低圧蓄圧器内の燃料
圧力が所定圧となるように当該低圧蓄圧器内の燃料を燃
料タンク（大気開放側）に排出する。In the low pressure accumulator, after the switching valve is closed, the high pressure fuel accumulated between the switching valve and the fuel chamber of the injector is regulated to obtain low pressure fuel. That is, the pressure control valve of the low-pressure accumulator connected to the fuel passage between the low-pressure accumulator and the fuel tank is duty-controlled so that the fuel pressure in the low-pressure accumulator becomes a predetermined pressure. Discharge the fuel to the fuel tank (open to the atmosphere).
【０００６】[0006]
【発明が解決しようとする課題】低圧蓄圧器と高圧蓄圧
器を燃料噴射中に切り換えて噴射波形の制御を行う上記
構成の蓄圧式燃料噴射装置において、高圧蓄圧器の燃料
圧を検知する圧力センサが故障した場合、信号出力が低
出力（低圧力）状態で故障したとき（例えば、断線等）
には、高圧蓄圧器の燃圧を上げようと制御するため高圧
蓄圧器の燃圧が上昇するが、最終的には高圧蓄圧器に設
置してあるリリーフ弁が作動し、高圧蓄圧器及び燃料通
路の損傷を防止することができる。In the pressure-accumulation type fuel injection device having the above-mentioned structure for controlling the injection waveform by switching the low pressure accumulator and the high pressure accumulator during fuel injection, a pressure sensor for detecting the fuel pressure of the high pressure accumulator. When the signal fails, the signal output fails when the output is low (low pressure) (for example, disconnection).
In order to raise the fuel pressure of the high pressure accumulator, the fuel pressure of the high pressure accumulator rises, but finally the relief valve installed in the high pressure accumulator operates and the high pressure accumulator and the fuel passage Damage can be prevented.
【０００７】しかしながら、常に、通常モードにおける
最高噴射圧以上の噴射圧で燃料を噴射することになり、
噴射量の増大、筒内最高圧力の増大、騒音振動の増大等
の不具合を招く。また、高圧蓄圧器の燃料圧を上げよう
とするため、高圧燃料ポンプが過剰な燃料圧送を繰り返
し、故障を招く虞がある。前記高圧蓄圧器の圧力センサ
が、信号出力が高出力（高圧力）状態で故障したときに
は、高圧蓄圧器の燃圧を下げようと制御するため、高圧
燃料ポンプからの燃料圧送が無くなり、燃料噴射に必要
な高圧蓄圧器の燃料圧を得られなくなる。そのため、エ
ンジン運転ができなくなる。However, the fuel is always injected at an injection pressure higher than the maximum injection pressure in the normal mode,
This causes problems such as an increase in the injection amount, an increase in the maximum cylinder pressure, and an increase in noise and vibration. Further, since the fuel pressure of the high-pressure accumulator is to be increased, the high-pressure fuel pump may repeatedly feed the excessive amount of fuel to cause a failure. When the pressure sensor of the high pressure accumulator fails in the state where the signal output is high output (high pressure), the pressure sensor controls to reduce the fuel pressure of the high pressure accumulator, so that the fuel pressure feeding from the high pressure fuel pump is eliminated and the fuel injection is performed. The required fuel pressure for the high pressure accumulator cannot be obtained. Therefore, the engine cannot be operated.
【０００８】また、低圧蓄圧器の燃料圧を検知する圧力
センサが故障した場合、信号出力が低出力（低圧力）状
態で故障したとき（例えば、断線等）には、低圧蓄圧器
の燃料圧を上げようと制御するため低圧蓄圧器の燃料圧
が上昇し、最終的には高圧蓄圧器の燃料圧と等しくな
る。それにより、噴射初期から高圧噴射となり、噴射量
が増大して過負荷運転となるため、そのままの異常な状
態でエンジンの運転を続けるとエンジンひいては車両に
損傷を与える場合が生ずる。また、低圧蓄圧器は、高圧
蓄圧器に対して、許容耐圧（許容圧力）が低く設定され
ているため、低圧蓄圧器内の燃料圧の過度な圧力上昇
は、低圧蓄圧器の損傷、燃料漏れ等を来す虞がある。Further, when the pressure sensor for detecting the fuel pressure of the low pressure accumulator fails, and when the signal output fails in a low output (low pressure) state (for example, disconnection), the fuel pressure of the low pressure accumulator is reduced. The fuel pressure in the low pressure accumulator rises because of the control to raise the pressure, and finally becomes equal to the fuel pressure in the high pressure accumulator. As a result, high-pressure injection occurs from the initial stage of injection, and the injection amount increases, resulting in overload operation. Therefore, if the engine continues to operate in the abnormal state, the engine and eventually the vehicle may be damaged. Also, since the low pressure accumulator is set to have a lower allowable pressure resistance (permissible pressure) than the high pressure accumulator, an excessive increase in fuel pressure in the low pressure accumulator causes damage to the low pressure accumulator and fuel leakage. And so on.
【０００９】前記低圧蓄圧器の圧力センサが、信号出力
が高出力（高圧力）状態で故障したときには、低圧蓄圧
器の燃料圧を下げようと制御するため、低圧噴射が不可
能な低圧蓄圧器圧力となり、高圧噴射のみとなる。その
ため、着火時期が遅れ、排気温度の上昇、トルク不足を
招き、エンジンに悪影響を及ぼす。このため、本発明で
は、蓄圧器の燃料圧を検出する燃圧検出手段が故障した
と判定したときには、エンジン運転領域を限定したリン
プホームモード制御を行い、エンジン故障等を未然に防
止するようにした蓄圧式燃料噴射装置を提供することを
目的としている。When the pressure sensor of the low pressure accumulator fails in the state where the signal output is high output (high pressure), it controls to reduce the fuel pressure of the low pressure accumulator, so that the low pressure accumulator is incapable of low pressure injection. It becomes pressure and only high-pressure injection becomes. Therefore, the ignition timing is delayed, the exhaust temperature rises, the torque becomes insufficient, and the engine is adversely affected. Therefore, in the present invention, when it is determined that the fuel pressure detection means for detecting the fuel pressure of the pressure accumulator has failed, the limp home mode control in which the engine operating range is limited is performed to prevent engine failure and the like. An object of the present invention is to provide a pressure accumulation type fuel injection device.
【００１０】[0010]
【課題を解決するための手段】上記目的を達成するた
め、本発明の請求項１では、燃料ポンプで加圧された高
圧燃料は、第１蓄圧器に貯溜され、第１制御弁、燃料通
路を介してエンジンの燃焼室内に噴射する燃料噴射ノズ
ルに供給されると共に、前記燃料通路に分岐通路を介し
て接続され、前記第１蓄圧器内の燃料圧よりも低圧の第
２蓄圧器に供給されて貯溜される。この第２蓄圧器の燃
料圧は、当該第２蓄圧器内の燃料を大気開放側へ排出す
る第２制御弁により制御される。制御手段は、前記第１
蓄圧器内の高圧燃料を前記第２蓄圧器に向かって排出す
べく前記第１制御弁を開弁制御し、且つ前記第２蓄圧器
の燃料圧を設定圧にすべく前記第２蓄圧器の燃料圧を検
出する圧力検出手段の出力に応じて前記第２制御弁を開
弁制御する。In order to achieve the above object, according to claim 1 of the present invention, high-pressure fuel pressurized by a fuel pump is stored in a first pressure accumulator, a first control valve, and a fuel passage. Is supplied to a fuel injection nozzle for injecting into the combustion chamber of the engine via the fuel cell, is connected to the fuel passage via a branch passage, and is supplied to a second pressure accumulator having a lower pressure than the fuel pressure in the first pressure accumulator. It is saved and stored. The fuel pressure of the second pressure accumulator is controlled by a second control valve that discharges the fuel in the second pressure accumulator to the atmosphere open side. The control means is the first
In order to discharge the high pressure fuel in the pressure accumulator toward the second pressure accumulator, the first control valve is controlled to open, and the fuel pressure of the second pressure accumulator is set to the set pressure. The second control valve is controlled to open according to the output of the pressure detection means for detecting the fuel pressure.
【００１１】制御手段は、第１蓄圧器の燃料圧を検出す
る第１燃圧検出手段が故障したとき、高圧燃料噴射が行
えないので、高圧・低圧の切換噴射を中止し、第２制御
弁を閉弁して燃料系即ち、第１蓄圧器と第２蓄圧器の燃
料圧を同一圧力として、第２蓄圧器の許容圧力にて燃料
噴射を行う。これによりリンプホームモードで適正制御
することが可能となり、エンジンの過負荷運転、等内圧
の上昇、振動騒音の増大、排気温度上昇等を抑制し、エ
ンジン本体、車両の故障等を回避する。When the first fuel pressure detecting means for detecting the fuel pressure of the first pressure accumulator fails, the control means cannot perform high pressure fuel injection, so the high pressure / low pressure switching injection is stopped and the second control valve is turned on. The valve is closed and the fuel pressure of the fuel system, that is, the first pressure accumulator and the second pressure accumulator is set to the same pressure, and fuel injection is performed at the allowable pressure of the second pressure accumulator. This makes it possible to perform appropriate control in the limp home mode, suppress overload operation of the engine, increase in constant internal pressure, increase in vibration noise, increase in exhaust temperature, etc., and avoid failure of the engine body and vehicle.
【００１２】請求項２の発明では、制御手段は、第２蓄
圧器の燃料圧を検出する第２燃圧検出手段が故障したと
き、第２蓄圧器内の圧力が不明になり、低圧蓄圧器の圧
力制御を正確に行うことができなくなり、許容圧力の小
さい第２蓄圧器の耐久性に問題が生じるが、高圧低圧の
切換噴射を中止し、第２制御弁を閉弁して燃料系の圧力
を均一にして第２蓄圧室の許容圧力で燃料噴射を行う。
これにより、リンプホームモードが可能となる。According to the second aspect of the present invention, when the second fuel pressure detecting means for detecting the fuel pressure of the second pressure accumulator fails in the control means, the pressure in the second pressure accumulator becomes unknown, and the low pressure accumulator is controlled. Pressure control cannot be performed accurately, and the durability of the second accumulator with a small allowable pressure becomes problematic. However, switching injection of high pressure and low pressure is stopped, the second control valve is closed, and the pressure of the fuel system is closed. Is made uniform and fuel is injected at the allowable pressure of the second pressure accumulating chamber.
This enables the limp home mode.
【００１３】[0013]
【発明の実施の形態】以下、図面を参照して本発明の好
適な実施例を例示的に詳しく説明する。図１は、本発明
の実施形態としての蓄圧式燃料噴射装置の概略構成図、
図２は、図１に示す燃料噴射装置の主要要素とエンジン
の各気筒のインジェクタとの接続を示す概略図である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a pressure accumulation type fuel injection device as an embodiment of the present invention,
FIG. 2 is a schematic diagram showing the connection between the main elements of the fuel injection device shown in FIG. 1 and the injectors of each cylinder of the engine.
【００１４】図１及び図２において、蓄圧式燃料噴射装
置は、例えば、直列６気筒のディーゼルエンジン（図示
せず）に搭載されるもので、高圧燃料ポンプ１は、例え
ば、図３に示すようなプランジャポンプ２０を２つ備
え、各プランジャポンプ２０は、前記直列６気筒エンジ
ンの前３気筒と後３気筒に夫々対応しており、前３気筒
のプランジャ２１、後３気筒のプランジャ２１を駆動す
る各カム２２は、夫々３つの山を備えており、高圧燃料
ポンプ軸が１回転する間に各プランジャ２１が３回の圧
送ストロークを実施して燃料を圧送するようになってい
る。圧送ストロークの調整は、プンランジャポンプ２０
の吐出側に設けられている電磁弁２３の閉弁時期を調整
することにより行われ、この電磁弁２３が開弁している
間は、プランジャポンプ２０の圧送動作が無効になるよ
うになっている。電磁弁２３は、後述する電子制御装置
８により制御される。1 and 2, the pressure-accumulation type fuel injection device is mounted on, for example, an in-line 6-cylinder diesel engine (not shown), and the high-pressure fuel pump 1 is, for example, as shown in FIG. Two plunger pumps 20 are provided, and each plunger pump 20 corresponds to the front 3 cylinders and the rear 3 cylinders of the inline 6-cylinder engine, and drives the front 3 cylinder plunger 21 and the rear 3 cylinder plunger 21. Each cam 22 has three ridges, and each plunger 21 carries out three pressure feeding strokes to feed the fuel while the high-pressure fuel pump shaft makes one revolution. The adjustment of the pumping stroke is performed by the Punlangja pump 20.
Is performed by adjusting the closing timing of the solenoid valve 23 provided on the discharge side of the plunger pump 20. While the solenoid valve 23 is open, the pumping operation of the plunger pump 20 is disabled. There is. The solenoid valve 23 is controlled by the electronic control unit 8 described later.
【００１５】図１に戻り、蓄圧式燃料噴射装置の制御手
段としての電子制御装置（ＥＣＵ）８は、エンジン回転
センサ８ａにより検出されたエンジン回転数Ｎｅと、ア
クセル開度センサ（図示せず）により検出されたアクセ
ルペダル踏込量（アクセル開度）Ａccとに応じて高圧燃
料ポンプ１の電磁弁２３を制御して圧送ストロークを可
変調整し、更に、高圧蓄圧器（第１蓄圧器）３に設けら
れている圧力センサ（第１燃圧検出手段）３ａにより検
出された燃料圧ＰHPに応じて圧送ストローク（吐出圧）
をフィードバック制御することにより、エンジン運転状
態に適合する高圧燃料を得るようになっている。Returning to FIG. 1, an electronic control unit (ECU) 8 as a control means of the pressure accumulating fuel injection system has an engine speed Ne detected by an engine speed sensor 8a and an accelerator opening sensor (not shown). The solenoid valve 23 of the high-pressure fuel pump 1 is controlled in accordance with the accelerator pedal depression amount (accelerator opening) Acc detected by to adjust the pressure-feeding stroke variably, and further to the high-pressure accumulator (first accumulator) 3. The pressure feeding stroke (discharge pressure) according to the fuel pressure P HP detected by the pressure sensor (first fuel pressure detecting means) 3a provided
The feedback control is performed to obtain high-pressure fuel suitable for the engine operating condition.
【００１６】高圧燃料ポンプ１により加圧された燃料
は、高圧蓄圧器３に貯溜される。この高圧蓄圧器３は、
各気筒に共通するものであり、燃料通路１０ａに連通し
ている。燃料通路１０ａの途中には、例えば、二方電磁
弁から成る燃料噴射率切換用の切換弁（第１制御弁）５
が各気筒毎に設けられ（図２）、当該切換弁５の直ぐ下
流に上流側から下流側にのみ燃料の流れを許容する逆止
弁３２が設けられている。The fuel pressurized by the high pressure fuel pump 1 is stored in the high pressure accumulator 3. This high pressure accumulator 3
It is common to each cylinder and communicates with the fuel passage 10a. A switching valve (first control valve) 5 for switching the fuel injection rate, which is, for example, a two-way solenoid valve, is provided in the middle of the fuel passage 10a.
Is provided for each cylinder (FIG. 2), and a check valve 32 that allows fuel flow only from the upstream side to the downstream side is provided immediately downstream of the switching valve 5.
【００１７】燃料通路１０ａには、逆止弁３２の下流に
おいて当該燃料通路１０ａから分岐した燃料通路１０ｂ
を介して各気筒に共通の低圧蓄圧器（第２蓄圧器）４が
接続されている。燃料通路１０ｂの途中には逆止弁６
と、当該逆止弁６をバイパスするバイパス通路が設けら
れており、このバイパス通路にオリフィス６ａが設けら
れている。逆止弁６は、低圧蓄圧器４から燃料通路１０
ａ方向にのみ燃料の流れを許容する。燃料通路１０ａ内
の燃料圧が燃料通路１０ｂ内の燃料圧よりも高い場合、
燃料通路１０ａ内の燃料がオリフィス６ａを通して燃料
通路１０ｂに流入し、更に低圧蓄圧器４に流入する。燃
料通路１０ｂの低圧蓄圧器４と燃料タンク１７との間に
は電子制御装置８の制御下で動作して低圧蓄圧器４の燃
料圧を制御する圧力制御弁（第２制御弁）３４が設けら
れている。また、図２に示すように低圧蓄圧器４には当
該低圧蓄圧器４内の燃料圧ＰLPを検出する圧力センサ４
ａ（第２燃圧検出手段）が設けられている。The fuel passage 10a has a fuel passage 10b branched from the fuel passage 10a downstream of the check valve 32.
A low pressure accumulator (second accumulator) 4 common to each cylinder is connected via the. Check valve 6 is provided in the middle of fuel passage 10b.
And a bypass passage that bypasses the check valve 6 is provided, and an orifice 6a is provided in the bypass passage. The check valve 6 extends from the low pressure accumulator 4 to the fuel passage 10
Allow fuel flow only in direction a. When the fuel pressure in the fuel passage 10a is higher than the fuel pressure in the fuel passage 10b,
The fuel in the fuel passage 10a flows into the fuel passage 10b through the orifice 6a and further into the low pressure accumulator 4. A pressure control valve (second control valve) 34, which operates under the control of the electronic control unit 8 and controls the fuel pressure of the low pressure accumulator 4, is provided between the low pressure accumulator 4 and the fuel tank 17 in the fuel passage 10b. Has been. Further, as shown in FIG. 2, the low pressure accumulator 4 has a pressure sensor 4 for detecting the fuel pressure P LP in the low pressure accumulator 4.
a (second fuel pressure detection means) is provided.
【００１８】電子制御装置８は、低圧蓄圧器４内の燃圧
が、エンジン回転数Ｎｅとアクセルペダル踏込量Ａccと
によって表されるエンジン運転状態に適合した圧力にな
るように、圧力センサ４ａにより検出した実圧力ＰLPに
基づいて圧力制御弁３４を制御する。エンジンの各気筒
に設けられている燃料噴射ノズルとしてのインジェクタ
９は、燃料通路１０ａにオリフィス１５を介して接続さ
れた圧力制御室１１及び燃料室（燃料溜まり）１２を有
し、圧力制御室１１は、オリフィス１６、燃料戻り通路
１０ｃを介して燃料タンク１７に接続されている。そし
て、燃料戻り通路１０ｃの途中に例えば、二方電磁弁か
らなる燃料噴射時期制御用の開閉弁７が接続されてい
る。尚、開閉弁７は、インジェクタ内に設置されていて
もよい。The electronic control unit 8 detects the fuel pressure in the low pressure accumulator 4 by the pressure sensor 4a so that the fuel pressure in the low pressure accumulator 4 becomes a pressure suitable for the engine operating condition represented by the engine speed Ne and the accelerator pedal depression amount Acc. The pressure control valve 34 is controlled based on the actual pressure P LP . The injector 9 as a fuel injection nozzle provided in each cylinder of the engine has a pressure control chamber 11 and a fuel chamber (fuel sump) 12 which are connected to a fuel passage 10 a through an orifice 15, and the pressure control chamber 11 Are connected to the fuel tank 17 via the orifice 16 and the fuel return passage 10c. An on-off valve 7 for controlling fuel injection timing, which is, for example, a two-way solenoid valve, is connected in the middle of the fuel return passage 10c. The on-off valve 7 may be installed in the injector.
【００１９】インジェクタ９は、ノズル（噴孔）９ａを
開閉するニードル弁１３と、圧力制御室１１内に摺動可
能に収納された油圧ピストン１４とを有し、ニードル弁
１３は、スプリング（図示せず）によりノズル９ａ側に
付勢されて閉弁されている。燃料通路１０ａから圧力制
御室１１と燃料室１２とに燃料が供給されると共に噴射
時期制御用の開閉弁７を閉弁されている場合前記スプリ
ングのばね力と燃料圧との合力がニードル弁１３に加わ
り、当該ニードル弁１３は、燃料室１２内の燃料圧に抗
してノズル９ａを閉塞する。開閉弁７が開弁して圧力制
御室１１内の燃料が燃料タンク１７側（大気開放側）へ
排出されると、燃料室１２内の燃料圧によりニードル弁
１３が前記スプリングのばね力に抗して油圧ピストン１
４側へ移動してノズル９ａが開口し、燃料室１２内の燃
料がノズル９ａからエンジンの燃焼室へ噴射される。The injector 9 has a needle valve 13 for opening and closing a nozzle (injection hole) 9a, and a hydraulic piston 14 slidably accommodated in the pressure control chamber 11, and the needle valve 13 has a spring (see FIG. The nozzle 9a is urged by a not shown) to close the valve. When fuel is supplied from the fuel passage 10a to the pressure control chamber 11 and the fuel chamber 12 and the opening / closing valve 7 for controlling the injection timing is closed, the resultant force of the spring force of the spring and the fuel pressure is the needle valve 13. In addition, the needle valve 13 closes the nozzle 9a against the fuel pressure in the fuel chamber 12. When the on-off valve 7 opens and the fuel in the pressure control chamber 11 is discharged to the fuel tank 17 side (atmosphere opening side), the needle valve 13 resists the spring force of the spring due to the fuel pressure in the fuel chamber 12. Then hydraulic piston 1
The nozzle 9a is opened by moving to the fourth side, and the fuel in the fuel chamber 12 is injected from the nozzle 9a into the combustion chamber of the engine.
【００２０】以下、上記構成の燃料噴射装置の通常モー
ドでの動作を説明する。電子制御装置８の制御下で、高
圧蓄圧器３内の燃料圧及び低圧蓄圧器４内の燃料圧がエ
ンジン運転状態に適合するように制御され、エンジン運
転状態（エンジン回転数、アクセルペダル踏込量等）に
応じて燃料噴射期間（燃料噴射開始・終了時期）及び低
圧噴射期間が設定される。The operation of the fuel injection device having the above structure in the normal mode will be described below. Under the control of the electronic control unit 8, the fuel pressure in the high pressure accumulator 3 and the fuel pressure in the low pressure accumulator 4 are controlled so as to match the engine operating state, and the engine operating state (engine speed, accelerator pedal depression amount) is controlled. Etc.), the fuel injection period (fuel injection start / end timing) and the low-pressure injection period are set.
【００２１】図４に示すように、燃料噴射開始時期が到
来するまでの間、切換弁５及び開閉弁７は、共に閉弁さ
れており、切換弁５の下流側の燃料通路１０ａには低圧
蓄圧器４から低圧燃料が供給され、この低圧燃料がイン
ジェクタ９の圧力制御室１１及び燃料室１２に供給され
る。開閉弁７が閉弁されていることで圧力制御室１１内
に供給された燃料圧が油圧ピストン１４を介してニード
ル弁１３に加わり、当該ニードル弁１３によりノズル９
ａが閉塞されて閉弁されている。As shown in FIG. 4, both the switching valve 5 and the on-off valve 7 are closed until the fuel injection start timing arrives, and the low pressure is provided in the fuel passage 10a on the downstream side of the switching valve 5. Low-pressure fuel is supplied from the pressure accumulator 4, and this low-pressure fuel is supplied to the pressure control chamber 11 and the fuel chamber 12 of the injector 9. Since the on-off valve 7 is closed, the fuel pressure supplied into the pressure control chamber 11 is applied to the needle valve 13 via the hydraulic piston 14, and the needle valve 13 causes the nozzle 9
a is closed and closed.
【００２２】燃料噴射開始時期になると、開閉弁７のみ
が開弁され、インジェクタ９の圧力制御室１１内の低圧
燃料がオリフィス１６及び燃料戻り通路１０ｃを通して
燃料タンク１７に排出される。これにより油圧ピストン
１４を介してニードル弁１３に加わる燃圧とスプリング
のばね力との合力が、当該ニードル弁１３を押し上げる
ように作用する燃料室１２内の燃圧よりも小さくなった
時点でニードル弁１３が上昇してノズル９ａが開口さ
れ、ノズル９ａから低圧燃料が噴射される。即ち、噴射
初期において比較的小さい燃料噴射率（単位時間当たり
の燃料噴射量）での低圧噴射が実行される。この低圧噴
射により、燃料噴射期間の初期段階での燃焼は、比較的
緩慢に行われ、排気ガス中のＮＯｘ量の低減が図られ
る。At the fuel injection start timing, only the on-off valve 7 is opened and the low pressure fuel in the pressure control chamber 11 of the injector 9 is discharged to the fuel tank 17 through the orifice 16 and the fuel return passage 10c. As a result, when the resultant force of the fuel pressure applied to the needle valve 13 via the hydraulic piston 14 and the spring force of the spring becomes smaller than the fuel pressure in the fuel chamber 12 that acts to push up the needle valve 13, the needle valve 13 Rise to open the nozzle 9a, and low-pressure fuel is injected from the nozzle 9a. That is, low-pressure injection is performed at a relatively low fuel injection rate (fuel injection amount per unit time) at the initial stage of injection. With this low-pressure injection, combustion in the initial stage of the fuel injection period is performed relatively slowly, and the NOx amount in the exhaust gas is reduced.
【００２３】低圧噴射を開始してから所定時間が経過す
ると、噴射時期制御用の開閉弁７が開弁された状態のま
ま、噴射率切換用の切換弁５が開弁され、燃料室１２に
高圧燃料が供給され、インジェクタ９から高圧燃料が噴
射される。即ち、低圧噴射での燃料噴射率よりも大きい
噴射率での高圧噴射が実行される。そして、燃料噴射終
了時期になると、噴射時期制御用の開閉弁７が閉弁さ
れ、燃料通路１０ａからオリフィス１５を通して圧力制
御室１１に供給された高圧燃料が油圧ピストン１４を介
してニードル弁１３に作用し、当該ニードル弁１３がノ
ズル９ａを閉塞し、ノズル９ａからの燃料噴射が終了す
る。燃料噴射終了時点で燃料噴射率が急速に立ち下がっ
てエンジンからの黒煙（スモーク）やパティキュレート
（粒状物質ＰＭ）の排出量が低減される。噴射率切換用
の切換弁５は、燃料噴射終了時期における開閉弁７の閉
弁と同時に閉弁され、或いは、燃料噴射時期終了時期か
ら所定時間が経過した時点で閉弁される。After a lapse of a predetermined time from the start of the low pressure injection, the switching valve 5 for switching the injection rate is opened and the fuel chamber 12 is opened while the open / close valve 7 for controlling the injection timing is kept open. The high-pressure fuel is supplied, and the high-pressure fuel is injected from the injector 9. That is, high-pressure injection is executed at an injection rate higher than the fuel injection rate at low-pressure injection. Then, at the fuel injection end timing, the on-off valve 7 for controlling the injection timing is closed, and the high-pressure fuel supplied from the fuel passage 10a to the pressure control chamber 11 through the orifice 15 is supplied to the needle valve 13 via the hydraulic piston 14. The needle valve 13 acts to close the nozzle 9a, and the fuel injection from the nozzle 9a ends. At the end of fuel injection, the fuel injection rate rapidly falls, and the emission of black smoke (smoke) and particulates (particulate matter PM) from the engine is reduced. The switching valve 5 for switching the injection rate is closed at the same time as the opening / closing valve 7 is closed at the fuel injection end timing, or is closed when a predetermined time has elapsed from the fuel injection timing end timing.
【００２４】図５に示すようにインジェクタ９の燃料室
１２と噴射率切換用の切換弁５との間において、燃料通
路１０ａ内の高圧燃料は、燃料通路１０ｂのオリフィス
６ａを通して低圧蓄圧器４に流入し、これにより、燃料
通路１０ａ内の燃料圧は、各回の燃料噴射サイクルでの
燃料噴射が終了した時点から漸減して、次回の燃料噴射
サイクルでの燃料噴射が開始されるまでに圧力制御弁３
４により設定される低圧噴射に適合する燃料圧に低下
し、次回の低圧噴射での噴射率は、所要のものとなる。As shown in FIG. 5, between the fuel chamber 12 of the injector 9 and the switching valve 5 for switching the injection rate, the high-pressure fuel in the fuel passage 10a passes through the orifice 6a of the fuel passage 10b to the low-pressure accumulator 4. As a result, the fuel pressure in the fuel passage 10a gradually decreases from the time when the fuel injection in each fuel injection cycle ends, and the pressure control is performed before the fuel injection in the next fuel injection cycle starts. Valve 3
The fuel pressure is set to a value suitable for the low pressure injection set by 4, and the injection rate in the next low pressure injection becomes the required one.
【００２５】既に説明したように、高圧蓄圧器３の燃料
圧を検知する圧力センサ３ａが、信号出力が低出力（低
圧力）状態で故障したときには、図６に実線で示すよう
に常に、点線で示す通常モードにおける最高噴射圧以上
の噴射圧で燃料を噴射することになり、噴射量の増大、
筒内最高圧力の増大、騒音振動の増大等の不具合を招
く。また、低圧蓄圧器４の燃料圧を検知する圧力センサ
４ａが、信号出力が低出力（低圧力）状態で故障したと
きには、図６に１点鎖線で示すように噴射初期から高圧
噴射即ち、通常モードにおける最高噴射圧（点線で示
す）となり、噴射量が増大して過負荷運転となる。この
ように高圧蓄圧器３の燃料圧を検出する圧力センサ３
ａ、または、低圧蓄圧器４の燃料圧を検出する圧力セン
サ４ａが故障した場合には、低圧噴射と高圧噴射の組合
せができなくなり、噴射量が異常となる。図６は、高圧
蓄圧器３の燃圧を検出する圧力センサ３ａ、及び低圧蓄
圧器４の燃料圧を検出する圧力センサ４ａが、夫々信号
出力が低出力状態で故障した場合の燃料噴射波形、イン
ジェクタ９及び切換弁５の駆動を示すタイミングチャー
トを示す。As described above, when the pressure sensor 3a for detecting the fuel pressure of the high pressure accumulator 3 fails in the state where the signal output is low output (low pressure), the dotted line is always present as shown by the solid line in FIG. Injecting fuel at an injection pressure higher than the maximum injection pressure in the normal mode indicated by, increases the injection amount,
This causes problems such as an increase in maximum cylinder pressure and noise and vibration. Further, when the pressure sensor 4a for detecting the fuel pressure of the low pressure accumulator 4 fails in the state where the signal output is low output (low pressure), as shown by the one-dot chain line in FIG. The maximum injection pressure in the mode (shown by the dotted line) is reached, the injection amount increases, and overload operation occurs. In this way, the pressure sensor 3 for detecting the fuel pressure of the high pressure accumulator 3
If a or the pressure sensor 4a that detects the fuel pressure of the low-pressure accumulator 4 fails, it becomes impossible to combine low-pressure injection and high-pressure injection, and the injection amount becomes abnormal. FIG. 6 shows a fuel injection waveform and an injector when the pressure sensor 3a for detecting the fuel pressure of the high-pressure accumulator 3 and the pressure sensor 4a for detecting the fuel pressure of the low-pressure accumulator 4 have failed in the low output state of the signal output, respectively. 9 is a timing chart showing driving of the switching valve 9 and the switching valve 5.
【００２６】そこで、本発明の蓄圧式燃料噴射装置で
は、電子制御装置８は、図８に示す蓄圧器圧力センサの
故障判定ルーチンを所定周期で実行する。図８に示す判
定ルーチンにおいて、高圧蓄圧器３の燃料圧を検出する
圧力センサ３ａが正常か否かを判定し（ステップＳ
１）、正常であるときには低圧蓄圧器４の燃料圧を検出
する圧力センサ４ａが正常か否かを判定し（ステップＳ
２）、圧力センサ４ａが正常であるときには通常制御モ
ードに移行し（ステップＳ４）、ステップＳ１で圧力セ
ンサ３ａが故障していると判定したときには故障時制御
モード（リンプホームモード）に移行する（ステップＳ
３）。Therefore, in the pressure-accumulation type fuel injection device of the present invention, the electronic control unit 8 executes the failure judgment routine of the pressure accumulator pressure sensor shown in FIG. 8 at a predetermined cycle. In the determination routine shown in FIG. 8, it is determined whether or not the pressure sensor 3a that detects the fuel pressure of the high pressure accumulator 3 is normal (step S
1) If it is normal, it is judged whether or not the pressure sensor 4a for detecting the fuel pressure of the low pressure accumulator 4 is normal (step S
2) If the pressure sensor 4a is normal, the normal control mode is entered (step S4), and if it is determined in step S1 that the pressure sensor 3a is out of order, the failure control mode (limp home mode) is entered (step S4). Step S
3).
【００２７】ステップＳ１における圧力センサ３ａの故
障判定は、電子制御装置８により、圧力センサ３ａから
の高圧蓄圧器３の実圧力と指示圧力（設定圧）の、或る
一定値以上の差が継続する期間と、或る一定期間におけ
る圧力センサ３ａの時間変化率の絶対値の平均値と圧力
センサ３ａの平均値の比をモニタして判定する。即ち、
（１）高圧蓄圧器３の指示圧力と実圧力との差が或る一
定時間以上続く場合、（２）或る一定期間における圧力
センサ３ａの出力の時間に対する変化率の平均値と出力
の平均値の比が或る一定値以下の場合、の２つの故障条
件を同時に満足する場合に、圧力センサ３ａが故障と判
定する。In the failure determination of the pressure sensor 3a in step S1, the electronic control unit 8 continues the difference between the actual pressure of the high pressure accumulator 3 from the pressure sensor 3a and the instruction pressure (set pressure) which is a certain value or more. And the ratio of the average value of the absolute values of the time rate of change of the pressure sensor 3a to the average value of the pressure sensor 3a during a certain period. That is,
(1) When the difference between the indicated pressure of the high-pressure accumulator 3 and the actual pressure continues for a certain fixed time or longer, (2) the average value of the rate of change of the output of the pressure sensor 3a with respect to time and the average of the output during a certain fixed period. When the ratio of the values is equal to or less than a certain fixed value and the two failure conditions of are simultaneously satisfied, it is determined that the pressure sensor 3a is in failure.
【００２８】図９は、高圧蓄圧器３の指示圧力と圧力セ
ンサ３ａの出力（実圧力）との関係を示す。図９におい
て実線は、圧力センサ３ａが正常な状態（実圧力＝指示
圧力）を示し、その両側に許容値（ヒステリシス）が設
定されて基準領域Ｉとされている。基準領域Ｉの下側の
領域IIは、実圧力が指示圧力よりも小さい領域、上側の
領域IIIは、実圧力が指示圧力よりも大きい領域であ
り、何れの領域においても圧力センサ３ａの第１の故障
条件が成立する。電子制御装置８は、領域II、IIの何れ
かの領域に或る一定時間以上継続した場合には、圧力セ
ンサ３が前記（１）の故障条件（第１の故障条件）に該
当するものと判定する。FIG. 9 shows the relationship between the indicated pressure of the high pressure accumulator 3 and the output (actual pressure) of the pressure sensor 3a. In FIG. 9, a solid line indicates a normal state (actual pressure = instruction pressure) of the pressure sensor 3a, and an allowable value (hysteresis) is set on both sides of the pressure sensor 3a to form a reference region I. An area II below the reference area I is an area where the actual pressure is smaller than the instructed pressure, and an area III above the reference area I is an area where the actual pressure is larger than the instructed pressure. The failure condition of is satisfied. The electronic control unit 8 determines that the pressure sensor 3 corresponds to the failure condition (first failure condition) of the above (1) when it continues in any one of the areas II and II for a certain time or more. judge.
【００２９】更に、電子制御装置８は、図１０に示すよ
うに或る一定時間Ｔsにおける、圧力センサ３ａの出力
の時間に対する変化率の絶対値の平均値をＡdp、圧力セ
ンサ３ａの出力の平均値をＡpとし、これらの比Ｒ（＝
Ａp／Ａdp）が或る一定値α以下（Ｒ＜α）のとき、圧
力センサ３ａが前記（２）の故障条件（第２の故障条
件）が成立するものと判定する。圧力センサ３ａが正常
の時にはその出力値は時間と共に変化し、出力の時間に
対する変化率の絶対値の平均値Ａdp、出力の平均値Ａp
は、夫々点線で示すように変化するが、異常のときには
出力値は一定となり変化せず、実線で示すようになる。
尚、出力の平均値Ａpを、出力の時間に対する変化率の
絶対値の平均値Ａdpで割ることで、無次元化している。
図１０は、或る一定時間Ｔsにおける、圧力センサ３ａ
の出力の時間に対する変化率の絶対値の平均値Ａdp、圧
力センサ３ａの出力の平均値Ａpの一例を示す。Further, as shown in FIG. 10, the electronic control unit 8 sets the average value of the absolute value of the change rate of the output of the pressure sensor 3a with respect to time at a certain time Ts to Adp, and the average output of the pressure sensor 3a. The value is Ap, and these ratios R (=
When Ap / Adp) is a certain value α or less (R <α), the pressure sensor 3a determines that the failure condition (2) (second failure condition) is satisfied. When the pressure sensor 3a is normal, its output value changes with time, and the average value Adp of the absolute value of the rate of change of the output with respect to time, the average value Ap of the output.
Respectively change as shown by the dotted line, but when they are abnormal, the output value becomes constant and does not change, and becomes as shown by the solid line.
It should be noted that the output average value Ap is made dimensionless by dividing it by the average value Adp of the absolute value of the change rate with respect to the output time.
FIG. 10 shows the pressure sensor 3a at a certain time Ts.
An example of the average value Adp of the absolute value of the change rate of the output of the above and the average value Ap of the output of the pressure sensor 3a is shown.
【００３０】また、ステップＳ２で行う低圧蓄圧器４の
燃料圧を検出する圧力センサ４ａの故障判定についても
高圧蓄圧器３の圧力センサ３ａの故障判定と全く同様で
あり、説明を省略する。尚、図９、図１０については、
括弧内の符号４ａを参照する。電子制御装置８は、図８
のステップＳ３の圧力センサ３ａの故障時制御モード
（リンプホームモード）において、燃料噴射量、噴射圧
力、低圧蓄圧器４の圧力制御弁３４を制御する各制御マ
ップを故障モード用に切り換えて制御する。即ち、図１
１に実線で示すように燃料噴射量制御は、点線で示す通
常モード（最大値）に対して実線で示すように最大噴射
量・エンジンの最高回転数（最大値）を制限する。図１
１は、エンジン回転数と燃料噴射量との関係を示す特性
図である。The failure determination of the pressure sensor 4a for detecting the fuel pressure of the low pressure accumulator 4 performed in step S2 is completely the same as the failure determination of the pressure sensor 3a of the high pressure accumulator 3, and the description thereof will be omitted. In addition, regarding FIG. 9 and FIG.
Reference numeral 4a in parentheses is referred to. The electronic control unit 8 is shown in FIG.
In the failure control mode (limp home mode) of the pressure sensor 3a in step S3, the control maps for controlling the fuel injection amount, the injection pressure, and the pressure control valve 34 of the low pressure accumulator 4 are switched for the failure mode and controlled. . That is, FIG.
1, the fuel injection amount control limits the maximum injection amount and the maximum engine speed (maximum value) of the engine as shown by the solid line for the normal mode (maximum value) shown by the dotted line. Figure 1
FIG. 1 is a characteristic diagram showing the relationship between the engine speed and the fuel injection amount.
【００３１】更に、電子制御装置８は、図１２に実線で
示すように高圧蓄圧器３の最高圧力（燃料圧）を所定圧
（以下「設定圧」という）に制御する。この設定圧は、
圧力制御弁３４を全閉状態で保持制御すると共に、最高
圧力は、低圧蓄圧器４の圧力センサ４ａの検出値を用い
て高圧燃料ポンプ１のプランジャ２１（図１）の圧送ス
トロークの有効区間を調整して吐出圧の最大圧力が点線
で示す通常制御時における高圧蓄圧器３の圧力（最大圧
力）よりも低く、通常制御時における低圧蓄圧器４の圧
力（最大圧力）よりも高く、且つ低圧蓄圧器４の許容耐
圧以下に制御する。これにより、高圧蓄圧器３の圧力＝
低圧蓄圧器４の圧力となる。このように高圧蓄圧器３の
最大圧力（燃圧）を低圧蓄圧器４の許容圧力以下とする
ことで、低圧蓄圧器４の損傷や、燃料漏れ等が防止され
る。図１２は、エンジン回転数と高圧蓄圧器３及び低圧
蓄圧器４の各圧力（燃圧）との関係を示す特性図であ
る。Further, the electronic control unit 8 controls the maximum pressure (fuel pressure) of the high pressure accumulator 3 to a predetermined pressure (hereinafter referred to as "set pressure") as shown by the solid line in FIG. This set pressure is
The pressure control valve 34 is controlled to be held in the fully closed state, and the maximum pressure is determined by using the detection value of the pressure sensor 4a of the low pressure accumulator 4 to determine the effective section of the pressure feeding stroke of the plunger 21 (FIG. 1) of the high pressure fuel pump 1. The maximum pressure of the adjusted discharge pressure is lower than the pressure (maximum pressure) of the high pressure accumulator 3 during normal control shown by the dotted line, higher than the pressure (maximum pressure) of the low pressure accumulator 4 during normal control, and low pressure. The pressure is controlled to be equal to or lower than the allowable withstand voltage of the accumulator 4. As a result, the pressure of the high pressure accumulator 3 =
It becomes the pressure of the low-pressure accumulator 4. By setting the maximum pressure (fuel pressure) of the high-pressure accumulator 3 to be equal to or lower than the allowable pressure of the low-pressure accumulator 4 in this way, damage to the low-pressure accumulator 4 and fuel leakage are prevented. FIG. 12 is a characteristic diagram showing a relationship between the engine speed and each pressure (fuel pressure) of the high pressure accumulator 3 and the low pressure accumulator 4.
【００３２】また、インジェクタ９・切換弁５の制御
は、通常制御時と同一マップを使用して制御の簡略化を
図る。高圧蓄圧器３の圧力＝低圧蓄圧器４の圧力となっ
ていることで、インジェクタ９の開弁時に噴射し、通常
モードに対する噴射時期の遅れは生じない。また、筒内
圧の上昇が防止される。図７は、圧力センサ３ａの故障
モード時における燃料噴射波形、インジェクタ９及び切
換弁５の駆動を示すタイミングチャートを示す。Further, the injector 9 and the switching valve 5 are controlled by using the same map as in the normal control to simplify the control. Since the pressure of the high-pressure accumulator 3 = the pressure of the low-pressure accumulator 4, the injection is performed when the injector 9 is opened, and the injection timing is not delayed with respect to the normal mode. In addition, the rise of the cylinder pressure is prevented. FIG. 7 is a timing chart showing a fuel injection waveform and driving of the injector 9 and the switching valve 5 in the failure mode of the pressure sensor 3a.
【００３３】図８のステップＳ２に示す圧力センサ４ａ
の故障判定で故障と判断されステップＳ３の故障時制御
モード（リンプホームモード）になった場合も、高圧蓄
圧器３の最高圧力（燃料圧）を圧力制御弁３４を全閉状
態で保持制御すると共に、低圧蓄圧器４の許容圧力以下
に制御する。これにより、高圧蓄圧器３の圧力＝低圧蓄
圧器４の圧力となる。他の制御についても先に説明した
圧力センサ３ａの故障時の場合と全く同様である。The pressure sensor 4a shown in step S2 of FIG.
Even when the failure determination is made and the failure control mode (limp home mode) of step S3 is entered, the maximum pressure (fuel pressure) of the high-pressure accumulator 3 is controlled to be maintained with the pressure control valve 34 fully closed. At the same time, the pressure is controlled to be equal to or lower than the allowable pressure of the low pressure accumulator 4. As a result, the pressure of the high pressure accumulator 3 = the pressure of the low pressure accumulator 4. The other control is exactly the same as in the case of the failure of the pressure sensor 3a described above.
【００３４】このように、電子制御装置８により高圧蓄
圧器３の燃料圧を検出する圧力センサ３ａ、又は低圧蓄
圧器４の燃料圧を検出する圧力センサ４ａの故障を判定
し、故障時にはリンプホームモードで適正制御をするこ
とで、エンジン過負荷運転、筒内圧の上昇、振動騒音の
増大、排気温度の上昇等を抑制することができ、修理工
場まで自走することが可能となる。In this way, the electronic control unit 8 determines the failure of the pressure sensor 3a for detecting the fuel pressure of the high-pressure accumulator 3 or the pressure sensor 4a for detecting the fuel pressure of the low-pressure accumulator 4, and when there is a failure, the limp home By performing appropriate control in the mode, it is possible to suppress engine overload operation, increase in cylinder pressure, increase in vibration noise, increase in exhaust temperature, etc., and it becomes possible to drive to a repair shop.
【００３５】[0035]
【発明の効果】本発明によれば、請求項１の発明では、
第１蓄圧器の燃料圧を検出する第１燃圧検出手段が故障
したとき、高圧燃料噴射が行えないので、高圧低圧の切
換噴射を中止し、第２制御弁を閉弁して燃料系を同一圧
力として、第２蓄圧器の許容圧力にて燃料噴射を行うこ
とにより、リンプホームモードで適正制御することが可
能となり、エンジンの過負荷運転、等内圧の上昇、振動
騒音の増大、排気温度上昇等を抑制し、エンジン本体、
車両の故障等を回避することができる。According to the present invention, in the invention of claim 1,
When the first fuel pressure detection means for detecting the fuel pressure of the first pressure accumulator fails, high-pressure fuel injection cannot be performed, so high-pressure low-pressure switching injection is stopped, the second control valve is closed, and the fuel system is the same. By performing fuel injection at the allowable pressure of the second pressure accumulator as the pressure, it is possible to perform appropriate control in the limp home mode, and to perform engine overload operation, increase in internal pressure, increase in vibration noise, and increase in exhaust temperature. The engine body,
It is possible to avoid a breakdown of the vehicle.
【００３６】請求項２では、第２蓄圧器の燃料圧を検出
する第２燃圧検出手段が故障したとき、第２蓄圧器内の
圧力が不明になり、低圧蓄圧器の圧力制御を正確に行う
ことができなくなり、許容圧力の小さい第２蓄圧器の耐
久性に問題が生じるが、高圧低圧の切換噴射を中止し、
第２制御弁を閉弁して燃料系の圧力を均一にして第２蓄
圧室の許容圧力で燃料噴射を行うことで、リンプホーム
モードが可能となる。In the second aspect, when the second fuel pressure detecting means for detecting the fuel pressure of the second pressure accumulator fails, the pressure in the second pressure accumulator becomes unknown, and the pressure control of the low pressure accumulator is accurately performed. However, the durability of the second pressure accumulator with a small allowable pressure becomes a problem, but the high pressure / low pressure switching injection is stopped,
By closing the second control valve to make the pressure of the fuel system uniform and performing fuel injection at the allowable pressure of the second pressure accumulating chamber, the limp home mode becomes possible.
【図１】本発明の実施の形態に係る蓄圧式燃料噴射装置
を示す概略図である。FIG. 1 is a schematic view showing a pressure accumulation type fuel injection device according to an embodiment of the present invention.
【図２】図１に示す燃料噴射装置の主要要素とエンジン
の各気筒のインジェクタとの接続を示す概略図である。FIG. 2 is a schematic diagram showing the connection between the main elements of the fuel injection device shown in FIG. 1 and the injectors of each cylinder of the engine.
【図３】図１に示す高圧燃料ポンプの概略図である。FIG. 3 is a schematic diagram of the high-pressure fuel pump shown in FIG.
【図４】通常モードで実施される一燃料噴射サイクルに
おける、時間経過に伴う噴射率の変化並びに噴射率切換
用の切換弁及び噴射時期制御用の開閉弁の各開閉状態の
変化を示す図である。FIG. 4 is a diagram showing changes in the injection rate with the passage of time, and changes in each open / closed state of a switching valve for switching the injection rate and an on-off valve for controlling injection timing in one fuel injection cycle executed in the normal mode. is there.
【図５】通常モードで実施される一燃料噴射サイクルに
おける、時間経過に伴うインジェクタと切換弁との間の
燃料通路内の燃料圧力の変化を示す図である。FIG. 5 is a diagram showing a change in fuel pressure in a fuel passage between an injector and a switching valve over time in one fuel injection cycle performed in a normal mode.
【図６】高圧蓄圧器の圧力センサ、又は低圧蓄圧器の圧
力センサが故障した場合の燃料噴射波形、インジェクタ
及び切換弁の駆動を示すタイミングチャートである。FIG. 6 is a timing chart showing driving of a fuel injection waveform, an injector and a switching valve when a pressure sensor of a high pressure accumulator or a pressure sensor of a low pressure accumulator fails.
【図７】高圧蓄圧器の圧力センサ、低圧蓄圧器の圧力セ
ンサの故障モード時における燃料噴射波形、インジェク
タ及び切換弁の駆動を示すタイミングチャートである。FIG. 7 is a timing chart showing driving of a fuel injection waveform, an injector and a switching valve in a failure mode of a pressure sensor of a high pressure accumulator and a pressure sensor of a low pressure accumulator.
【図８】図１に示す蓄圧式燃料噴射装置の高圧蓄圧器及
び低圧蓄圧器の圧力センサ故障判定ルーチンのフローチ
ャートである。8 is a flowchart of a pressure sensor failure determination routine of a high pressure accumulator and a low pressure accumulator of the accumulator fuel injection device shown in FIG.
【図９】高圧蓄圧器の圧力センサの故障判定条件の１つ
を示し、高圧蓄圧器の指示圧力と圧力センサ出力（実圧
力）との関係を示す特性図である。FIG. 9 is a characteristic diagram showing one of the failure determination conditions of the pressure sensor of the high pressure accumulator and showing the relationship between the instruction pressure of the high pressure accumulator and the pressure sensor output (actual pressure).
【図１０】蓄圧器の圧力センサの故障判定条件の１つを
示し、圧力センサ出力の変化を示すグラフである。FIG. 10 is a graph showing one of failure determination conditions of the pressure sensor of the pressure accumulator and showing a change in pressure sensor output.
【図１１】エンジン回転数と燃料噴射量との関係を示す
特性図である。FIG. 11 is a characteristic diagram showing a relationship between an engine speed and a fuel injection amount.
【図１２】エンジン回転数と高圧及び低圧蓄圧器の圧力
（燃料圧）との関係を示す特性図である。FIG. 12 is a characteristic diagram showing the relationship between the engine speed and the pressure (fuel pressure) of the high pressure and low pressure accumulators.
１ 高圧燃料ポンプ
３ 高圧蓄圧器（第１蓄圧器）
４ 低圧蓄圧器（第２蓄圧器）
３ａ 圧力センサ（第１燃圧検出手段）
４ａ 圧力センサ（第２燃圧検出手段）
５ 高圧・低圧蓄圧器（燃料噴射率）切換用の切換弁
（第１制御弁）
７ 噴射時期制御用の開閉弁
８ 電子制御装置（制御手段）
９ インジェクタ（燃料噴射ノズル）
１０ａ、１０ｂ 燃料通路
２０ プランジャポンプ
２１ プランジャ
２２ カム
３４ 低圧蓄圧器の圧力制御弁（第２制御弁）1 High-pressure fuel pump 3 High-pressure accumulator (first accumulator) 4 Low-pressure accumulator (second accumulator) 3a Pressure sensor (first fuel pressure detection means) 4a Pressure sensor (second fuel pressure detection means) 5 High-pressure / low-pressure accumulator Switching valve (first control valve) for switching (fuel injection rate) 7 Open / close valve for controlling injection timing 8 Electronic control device (control means) 9 Injector (fuel injection nozzle) 10a, 10b Fuel passage 20 Plunger pump 21 Plunger 22 Cam 34 Pressure control valve for low pressure accumulator (second control valve)
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ Ｆ０２Ｍ 55/02 ３５０ Ｆ０２Ｍ 55/02 ３５０Ｅ 63/00 63/00 Ｕ (56)参考文献 特開 平10−227268（ＪＰ，Ａ) 特開 平８−284722（ＪＰ，Ａ) 特開 平６−93936（ＪＰ，Ａ) 特開 平８−296520（ＪＰ，Ａ) 特開 平11−2148（ＪＰ，Ａ) 特開 平10−77892（ＪＰ，Ａ) 国際公開98／009068（ＷＯ，Ａ１) (58)調査した分野(Int.Cl.7，ＤＢ名) F02D 41/00 F02D 45/00 F02M 47/00 F02M 55/02 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 7 Identification symbol FI F02M 55/02 350 F02M 55/02 350E 63/00 63/00 U (56) Reference JP-A-10-227268 (JP, A ) JP-A-8-284722 (JP, A) JP-A-6-93936 (JP, A) JP-A-8-296520 (JP, A) JP-A-11-2148 (JP, A) JP-A-10- 77892 (JP, A) International Publication 98/009068 (WO, A1) (58) Fields investigated (Int.Cl. 7 , DB name) F02D 41/00 F02D 45/00 F02M 47/00 F02M 55/02
Claims (2)
を貯溜する第１蓄圧器と、 前記第１蓄圧器と夫々燃料通路を介して接続され燃料を
各気筒の燃焼室内に噴射する燃料噴射ノズルと、 前記各燃料通路に配置され前記第１蓄圧器内の高圧燃料
を前記燃料通路下流側へ排出制御する第１制御弁と、 前記第１蓄圧器内の高圧燃料よりも低圧の燃料を貯溜し
前記第１制御弁より下流側の前記燃料通路に分岐通路を
介して接続される第２蓄圧器と、 前記第２蓄圧器内の燃料を大気開放側へ排出制御する第
２制御弁と、 前記第１蓄圧器内の燃料圧を検出する第１燃圧検出手段
と、 前記第２蓄圧器内の燃料圧を検出する第２燃圧検出手段
と、 前記燃料噴射ノズルの開弁期間の途中で前記第１制御弁
を開弁させ、且つ前記燃料噴射ノズルの閉弁に合わせて
前記第１制御弁を閉弁させるとともに、前記第１燃圧検
出手段が故障したと判定したときには、前記第２制御弁
を閉弁し、且つ前記燃料通路内が前記第２蓄圧器の許容
圧力以下となるように前記第２燃圧検出手段の出力に応
じて前記燃料ポンプの吐出圧力を制御する制御手段とを
有したことを特徴とする蓄圧式燃料噴射装置。1. A first pressure accumulator for storing high-pressure fuel pressurized by a fuel pump, and fuel injection for injecting fuel into the combustion chamber of each cylinder, which is connected to the first pressure accumulator via a fuel passage, respectively. A nozzle; a first control valve disposed in each of the fuel passages for controlling discharge of high-pressure fuel in the first pressure accumulator to a downstream side of the fuel passage; and a fuel having a lower pressure than the high-pressure fuel in the first accumulator. A second pressure accumulator that stores and is connected to the fuel passage downstream of the first control valve via a branch passage; and a second control valve that controls the discharge of the fuel in the second pressure accumulator to the atmosphere open side. A first fuel pressure detecting means for detecting a fuel pressure in the first pressure accumulator, a second fuel pressure detecting means for detecting a fuel pressure in the second pressure accumulator, and during a valve opening period of the fuel injection nozzle. The first control valve is opened and the fuel injection nozzle is closed. To close the first control valve, and when it is determined that the first fuel pressure detecting means has failed, the second control valve is closed and the inside of the fuel passage is the allowable pressure of the second pressure accumulator. A pressure accumulation type fuel injection device, comprising: a control unit that controls the discharge pressure of the fuel pump according to the output of the second fuel pressure detection unit as described below.
を貯溜する第１蓄圧器と、 前記第１蓄圧器と夫々燃料通路を介して接続され燃料を
各気筒の燃焼室内に噴射する燃料噴射ノズルと、 前記各燃料通路に配置され前記第１蓄圧器内の高圧燃料
を前記燃料通路下流側へ排出制御する第１制御弁と、 前記第１蓄圧器内の高圧燃料よりも低圧の燃料を貯溜し
前記第１制御弁より下流側の前記燃料通路に分岐通路を
介して接続される第２蓄圧器と、 前記第２蓄圧器内の燃料を大気開放側へ排出制御する第
２制御弁と、 前記第１蓄圧器内の燃料圧を検出する第１燃圧検出手段
と、 前記第２蓄圧器内の燃料圧を検出する第２燃圧検出手段
と、 前記燃料噴射ノズルの開弁期間の途中で前記第１制御弁
を開弁させ、且つ前記燃料噴射ノズルの閉弁に合わせて
前記第１制御弁を閉弁させるとともに、前記第２燃圧検
出手段が故障したと判定したときには、前記第２制御弁
を閉弁し、且つ前記燃料通路内が前記第２蓄圧器の許容
圧力以下となるように前記第１燃圧検出手段の出力に応
じて前記燃料ポンプの吐出圧力を制御する制御手段とを
有したことを特徴とする蓄圧式燃料噴射装置。2. A first pressure accumulator that stores high-pressure fuel pressurized by a fuel pump, and a fuel injection that is connected to the first pressure accumulator via a fuel passage and injects fuel into a combustion chamber of each cylinder. A nozzle; a first control valve disposed in each of the fuel passages for controlling discharge of high-pressure fuel in the first pressure accumulator to a downstream side of the fuel passage; and a fuel having a lower pressure than the high-pressure fuel in the first accumulator. A second pressure accumulator that stores and is connected to the fuel passage downstream of the first control valve via a branch passage; and a second control valve that controls the discharge of the fuel in the second pressure accumulator to the atmosphere open side. A first fuel pressure detecting means for detecting a fuel pressure in the first pressure accumulator, a second fuel pressure detecting means for detecting a fuel pressure in the second pressure accumulator, and during a valve opening period of the fuel injection nozzle. The first control valve is opened and the fuel injection nozzle is closed. To close the first control valve, and when it is determined that the second fuel pressure detecting means has failed, the second control valve is closed and the inside of the fuel passage is the allowable pressure of the second pressure accumulator. A pressure accumulation type fuel injection device, comprising: a control unit that controls the discharge pressure of the fuel pump according to the output of the first fuel pressure detection unit as described below.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33573598A JP3416682B2 (en) | 1998-11-26 | 1998-11-26 | Accumulator type fuel injection device |
| EP99122967A EP1008741B1 (en) | 1998-11-20 | 1999-11-18 | Accumulator type fuel injection system |
| DE69906459T DE69906459T2 (en) | 1998-11-20 | 1999-11-18 | Fuel injection device of the Accumulatorgattung |
| US09/758,944 US6378498B2 (en) | 1998-11-20 | 2001-01-11 | Accumulator type fuel injection system |
| US10/074,496 US6792919B2 (en) | 1998-11-20 | 2002-02-11 | Accumulator type fuel injection system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33573598A JP3416682B2 (en) | 1998-11-26 | 1998-11-26 | Accumulator type fuel injection device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000161114A JP2000161114A (en) | 2000-06-13 |
| JP3416682B2 true JP3416682B2 (en) | 2003-06-16 |
Family
ID=18291898
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33573598A Expired - Fee Related JP3416682B2 (en) | 1998-11-20 | 1998-11-26 | Accumulator type fuel injection device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3416682B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011046074A1 (en) * | 2009-10-13 | 2011-04-21 | ボッシュ株式会社 | Pressure sensor diagnostic method and common rail fuel injection control device |
| WO2011077951A1 (en) * | 2009-12-22 | 2011-06-30 | 日産自動車株式会社 | Fuel supply device for an internal combustion engine, and fuel supply control method |
| CN111022231A (en) * | 2019-11-26 | 2020-04-17 | 潍柴重机股份有限公司 | V-type engine master-slave train rail pressure synchronous control method and control system |
-
1998
- 1998-11-26 JP JP33573598A patent/JP3416682B2/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011046074A1 (en) * | 2009-10-13 | 2011-04-21 | ボッシュ株式会社 | Pressure sensor diagnostic method and common rail fuel injection control device |
| JP5336602B2 (en) * | 2009-10-13 | 2013-11-06 | ボッシュ株式会社 | Pressure sensor diagnosis method and common rail fuel injection control device |
| WO2011077951A1 (en) * | 2009-12-22 | 2011-06-30 | 日産自動車株式会社 | Fuel supply device for an internal combustion engine, and fuel supply control method |
| US9279404B2 (en) | 2009-12-22 | 2016-03-08 | Nissan Motor Co., Ltd. | Fuel supply device and fuel supply control method for internal combustion engine |
| CN111022231A (en) * | 2019-11-26 | 2020-04-17 | 潍柴重机股份有限公司 | V-type engine master-slave train rail pressure synchronous control method and control system |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000161114A (en) | 2000-06-13 |
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