JP3377034B2 - Accumulator type fuel injection device - Google Patents
Accumulator type fuel injection deviceInfo
- Publication number
- JP3377034B2 JP3377034B2 JP33573498A JP33573498A JP3377034B2 JP 3377034 B2 JP3377034 B2 JP 3377034B2 JP 33573498 A JP33573498 A JP 33573498A JP 33573498 A JP33573498 A JP 33573498A JP 3377034 B2 JP3377034 B2 JP 3377034B2
- Authority
- JP
- Japan
- Prior art keywords
- fuel
- pressure
- valve
- pressure accumulator
- accumulator
- 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
- Fuel-Injection Apparatus (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (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 duty control is performed on the pressure control valve of the low pressure accumulator connected to the fuel passage between the low pressure accumulator and the fuel tank 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】しかしながら、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、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率
を切り換える切換弁が故障した場合、例えば、６気筒中
又は４気筒中の１気筒の切換弁が故障した場合、当該気
筒の燃料噴射圧力、燃料噴射量が残りの他の気筒と比べ
て異常となるため、エンジン出力の低下、トルク変動の
増大等を招き、正常にはエンジンを運転することができ
なくなる。また、このような異常な状態でエンジンの運
転を続けた場合、過負荷、排気温度の上昇等により、エ
ンジンひいては車両に損傷を与える場合が生ずる等の問
題がある。However, 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, the accumulator type fuel injector is installed corresponding to the injector of each cylinder. When a switching valve for switching a certain fuel injection rate has failed, for example, when a switching valve for one cylinder out of 6 cylinders or 4 cylinders has failed, the fuel injection pressure and fuel injection amount of the cylinder concerned are different. Since the engine is abnormal compared to the cylinder, the engine output is reduced, the torque fluctuation is increased, and the engine cannot be operated normally. Further, when the engine continues to operate in such an abnormal state, there is a problem that the engine and eventually the vehicle may be damaged due to an overload, a rise in exhaust temperature, and the like.
【０００７】また、低圧蓄圧器に設置してある圧力制御
弁が故障した場合、閉弁故障時には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、燃料噴
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、燃料漏れ等を招く虞がある。When the pressure control valve installed in the low pressure accumulator fails, the fuel pressure in the low pressure accumulator rises when the valve closes, and eventually becomes equal to the fuel pressure in the high pressure accumulator. As a result, high-pressure injection is performed from the initial stage of injection, the fuel injection amount increases, and overload operation occurs, so if the engine operation continues in the abnormal state as it is, the engine and eventually the vehicle may be damaged. In addition, the low pressure accumulator
Since the allowable pressure resistance (allowable pressure) is set low for the high pressure accumulator, an excessive increase in fuel pressure in the low pressure accumulator may cause damage to the low pressure accumulator, fuel leakage, and the like.
【０００８】また、前記圧力制御弁が開弁故障時には、
低圧噴射が不可能となり、高圧噴射（主噴射）のみとな
るため、着火時期が遅れ、排気音度の上昇、トルク不足
を招き、エンジンに悪影響を及ぼす。また、低圧蓄圧器
の圧力を上げようとするため、高圧燃料供給ポンプが過
剰な燃料圧送を繰り返し、当該高圧燃料供給ポンプの故
障を招く虞がある。When the pressure control valve fails to open,
Since low-pressure injection becomes impossible and only high-pressure injection (main injection) is performed, ignition timing is delayed, exhaust sound level rises, torque is insufficient, and the engine is adversely affected. Further, since the pressure of the low-pressure accumulator is going to be increased, the high-pressure fuel supply pump may repeatedly carry out excessive pressure-feeding of the fuel, resulting in failure of the high-pressure fuel supply pump.
【０００９】このため、本発明では、各気筒の燃料噴射
ノズルに対応して設置されている燃料噴射率を切り換え
る切換弁の故障判定、低圧蓄圧器の圧力を制御する圧力
制御弁の故障判定を行い、故障時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。Therefore, according to the present invention, it is possible to determine the failure of the switching valve installed to correspond to the fuel injection nozzle of each cylinder for switching the fuel injection rate and the failure of the pressure control valve for controlling the pressure of the low pressure accumulator. It is an object of the present invention to provide a pressure-accumulation type fuel injection device that performs limp home mode control that limits the engine operating range when a failure occurs and prevents an engine failure or the like.
【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 a second passage, is connected to the fuel passage through a branch passage, and has a second pressure lower than the fuel pressure in the first pressure accumulator.
It is supplied to the pressure accumulator 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 controls the opening of the first control valve to discharge the high-pressure fuel in the first pressure accumulator toward the second pressure accumulator, and sets the fuel pressure of the second pressure accumulator to a set pressure. Therefore, the second control valve is controlled to open.
【００１１】制御手段は、複数の第１制御弁の少なくと
も１つが故障したと判定したとき、又は第２制御弁が閉
弁状態で故障したと判定したときには、燃料ポンプの吐
出圧力を第２蓄圧器の許容圧以下に設定する。この結
果、燃料ポンプにより第２蓄圧器の許容圧以下の燃料噴
射を行うことができる。請求項２の発明では、制御手段
は、第２制御弁が開弁状態で故障したと判定したときに
は、燃料ポンプの吐出圧を第２蓄圧器の許容圧以下に設
定し、且つ第１制御弁の開弁時間を燃料噴射ノズルの開
弁時期より前に設定する。これにより、燃料噴射ノズル
の開弁時期に燃料噴射を開始することができ、低圧噴射
ができなくなったために生じた噴射時期の遅れを防止す
る。請求項３の発明では、制御手段は、複数の第１制御
弁の少なくとも１つが開弁状態で故障したと判定したと
きには、燃料ポンプの吐出圧を第２蓄圧器の許容圧以下
に設定すると共に、故障した第１制御弁以外の正常な第
１制御弁の開弁時間を燃料噴射ノズルの開弁時期より前
に設定する。これにより、第１制御弁が故障した気筒
と、第１制御弁が正常な他の気筒の燃料噴射圧が同一と
なる。即ち、第１制御弁が正常な気筒は、全噴射期間中
に亘って前記第１制御弁が故障している気筒と同じ条件
となり、全気筒の噴射波形を揃えることができ、気筒間
のトルク差がなくなり、トルク変動が抑制されて、エン
ジン振動が抑制される。 When it is determined that at least one of the plurality of first control valves has failed, or when the second control valve has failed in the closed state, the control means sets the discharge pressure of the fuel pump to the second accumulated pressure. Set below the allowable pressure of the vessel. As a result, the fuel pump can inject fuel at a pressure equal to or lower than the allowable pressure of the second pressure accumulator. According to the second aspect of the invention, the control means sets the discharge pressure of the fuel pump to be equal to or lower than the allowable pressure of the second pressure accumulator when it is determined that the second control valve has failed in the open state, and the first control valve. The valve opening time of is set before the valve opening timing of the fuel injection nozzle. As a result, fuel injection can be started at the valve opening timing of the fuel injection nozzle, and the delay of the injection timing caused by the inability to perform low pressure injection can be prevented. In the invention of claim 3, the control means sets the discharge pressure of the fuel pump to be equal to or lower than the allowable pressure of the second pressure accumulator when it is determined that at least one of the plurality of first control valves has failed in the open state. The normal valve opening time of the first control valve other than the failed first control valve is set before the valve opening timing of the fuel injection nozzle. As a result, the fuel injection pressure of the cylinder in which the first control valve has failed becomes the same as that of the other cylinder in which the first control valve is normal. That is, the cylinder in which the first control valve is normal has the same condition as the cylinder in which the first control valve has failed over the entire injection period, and the injection waveforms of all the cylinders can be made uniform, and the torque between the cylinders can be reduced. There is no difference, torque fluctuations are suppressed, and engine vibration is suppressed .
【００１２】[0012]
【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.
【００１３】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 inline 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.
【００１４】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 accumulation type fuel injection device 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.
【００１５】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.
【００１６】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内の燃圧ＰLPを検出する圧力センサ４ａ
（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. As shown in FIG. 2, the low pressure accumulator 4 has a pressure sensor 4a for detecting the fuel pressure P LP in the low pressure accumulator 4.
(Second fuel pressure detection means) is provided.
【００１７】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 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.
【００１８】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.
【００１９】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.
【００２０】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９ａ
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 opening / closing 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 9a to
Is closed and closed.
【００２１】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.
【００２２】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 opening / closing 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.
【００２３】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 reach 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.
【００２４】既に説明したように、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率を切り換える切換
弁が故障した場合例えば、図２に示す６気筒中の第１気
筒の切換弁５-1が故障した場合には、当該第１気筒への
燃料噴射圧力及び燃料噴射量が、残りの他の気筒と比べ
て異常となるため、エンジン出力の低下、トルク変動の
増大等を来たし、正常にはエンジンを運転することがで
きなくなる。As described above, when the switching valve for switching the fuel injection rate installed corresponding to the injector of each cylinder fails, for example, the switching valve 5-of the first cylinder among the six cylinders shown in FIG. If 1 fails, the fuel injection pressure and fuel injection amount into the first cylinder become abnormal compared to the other cylinders, resulting in a decrease in engine output, an increase in torque fluctuation, etc. Will not be able to drive the engine.
【００２５】即ち、インジェクタ・切換弁の制御におい
て、第１気筒の切換弁５-1が閉弁状態で故障した場合の
噴射波形は、図６に示すように切換弁が正常な他の気筒
の噴射波形（点線で示す）に対して高圧噴射が行われな
い低圧噴射のみの異常な噴射となる。従って、切換弁５
-1の第１気筒だけ高圧噴射ができなくなり、他の気筒に
比べて燃料噴射量が少なくなる。このように６気筒中１
気筒だけ燃料量が少なくなるためにトルク変動が大きく
なり、エンジンの振動が大きくなる。図６は、図２の切
換弁５-1が閉弁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５-1の駆動を示すタイミングチ
ャートを示す。That is, in the injector / switching valve control, the injection waveform when the switching valve 5-1 of the first cylinder fails in the closed state is as shown in FIG. With respect to the injection waveform (shown by the dotted line), only the low-pressure injection that does not perform the high-pressure injection becomes abnormal injection. Therefore, the switching valve 5
High-pressure injection cannot be performed only for the -1st cylinder, and the fuel injection amount becomes smaller than other cylinders. 1 out of 6 cylinders
Since the amount of fuel in only the cylinder is small, the torque fluctuation is large and the engine vibration is large. FIG. 6 is a timing chart showing the fuel injection waveform and the drive of the injector 9 and the switching valve 5-1 when the switching valve 5-1 of FIG. 2 fails in the closed state.
【００２６】また、切換弁５-1が開弁状態で故障した場
合の噴射波形は、図７に示すように切換弁が正常な気筒
の噴射波形（点線で示す）に対して低圧噴射が行われな
い高圧噴射のみの波形となる。従って、当該切換弁５-1
の第１気筒だけ他の気筒よりも燃料量が多くなる。この
ように６気筒中１気筒だけ燃料量が多くなくためにトル
ク変動が大きくなり、エンジンの振動が大きくなる。し
かも、切換弁５-1が故障した第１気筒だけ設定燃料量を
超えて燃料を噴射することとなり、当該第１気筒だけが
過負荷となり、エンジンが焼き付く虞がある。図７は、
図２の切換弁５-1が開弁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５-1の駆動を示すタイ
ミングチャートを示す。As shown in FIG. 7, the injection waveform when the switching valve 5-1 fails when the switching valve 5-1 is open is low-pressure injection with respect to the injection waveform of the cylinder in which the switching valve is normal (shown by the dotted line). The waveform is only for high-pressure injection. Therefore, the switching valve 5-1
The fuel amount of only the first cylinder is larger than that of the other cylinders. As described above, since the fuel amount is small in only one cylinder among the six cylinders, the torque fluctuation becomes large and the engine vibration becomes large. Moreover, only the first cylinder in which the switching valve 5-1 has failed will inject fuel in excess of the set fuel amount, and only the first cylinder will be overloaded, and the engine may burn. Figure 7
3 is a timing chart showing a fuel injection waveform, driving of the injector 9 and the switching valve 5-1 when the switching valve 5-1 of FIG. 2 fails in the open state.
【００２７】このようにどの切換弁５が閉弁状態又は開
弁状態の何れの状態で故障した場合でも、低圧噴射と高
圧噴射の組合せができなくなり、切換弁が正常な他の気
筒に対して噴射量が異常となる。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９に示す切
換弁故障判定ルーチンを所定周期で実行する。この判定
ルーチンにおいて、高圧燃料と低圧燃料の噴射を切り換
える噴射率切換用の切換弁５が正常か否かを判定し（ス
テップＳ１）、正常であるときには通常制御モードに移
行し（ステップＳ２）、故障しているときには故障時制
御モード（リンプホームモード）に移行する（ステップ
Ｓ３）。In this way, no matter which switching valve 5 fails in the closed state or the open state, the combination of the low pressure injection and the high pressure injection cannot be performed, and the other switching cylinders have normal switching valves. The injection amount becomes abnormal. Therefore, in the pressure-accumulation fuel injection device of the present invention, the electronic control device 8 executes the switching valve failure determination routine shown in FIG. 9 at a predetermined cycle. In this judgment routine, it is judged whether or not the switching valve 5 for switching the injection rate for switching the injection of the high-pressure fuel and the low-pressure fuel is normal (step S1), and when it is normal, the normal control mode is entered (step S2), If there is a failure, the control mode is shifted to the failure control mode (limp home mode) (step S3).
【００２８】ステップＳ１における切換弁５の故障判定
は、電子制御装置８により低圧蓄圧器４の燃料圧を制御
する圧力制御弁３４の負荷状態をモニタして判定する。
この切換弁５の故障判定は、閉弁状態で故障している場
合と、開弁状態で故障している場合との２通りを判定す
る。切換弁５-1が閉弁状態で故障した場合には、燃料通
路１０ａから低圧蓄圧器４への高圧燃料の供給が、当該
切換弁５-1を通して供給される分だけ少なくなる。この
ため、低圧蓄圧器４の燃料圧を制御する圧力制御弁３４
（図１、図２）のデューティ比（開弁率）を通常状態よ
りも小さくして（閉弁時間を長くして）燃料タンク１７
に排出される燃料量を少なくしないと、低圧蓄圧器４の
燃料圧が設定圧力にならない。このため圧力制御弁３４
のデューティ比（負荷）が小さくなる。The failure judgment of the switching valve 5 in step S1 is judged by monitoring the load state of the pressure control valve 34 for controlling the fuel pressure of the low pressure accumulator 4 by the electronic control unit 8.
There are two types of failure determination for the switching valve 5, that is, a failure in the closed state and a failure in the open state. When the switching valve 5-1 fails in the closed state, the supply of high pressure fuel from the fuel passage 10a to the low pressure accumulator 4 is reduced by the amount supplied through the switching valve 5-1. Therefore, the pressure control valve 34 that controls the fuel pressure of the low pressure accumulator 4 is used.
The fuel tank 17 is configured so that the duty ratio (valve opening rate) of (FIGS. 1 and 2) is smaller than that in the normal state (valve closing time is lengthened).
The fuel pressure in the low-pressure accumulator 4 does not reach the set pressure unless the amount of fuel discharged to is reduced. Therefore, the pressure control valve 34
The duty ratio (load) becomes smaller.
【００２９】また、切換弁５-1が開弁状態で故障した場
合には、燃料通路１０ａから低圧蓄圧器４への高圧燃料
の供給量が、当該切換弁５-1を通して供給される分だけ
増大するために当該低圧蓄圧器４の燃料圧を制御する圧
力制御弁３４のデューティ比を通常状態よりも大きくし
て（開弁時間を長くして）多量の燃料を燃料タンク１７
に排出しないと、低圧蓄圧器４の燃料圧が設定圧力にな
らない。このため圧力制御弁３４のデューティ比（負
荷）が大きくなる。When the switching valve 5-1 fails in the open state, the amount of high-pressure fuel supplied from the fuel passage 10a to the low-pressure accumulator 4 is equal to the amount supplied through the switching valve 5-1. In order to increase the pressure, the duty ratio of the pressure control valve 34 that controls the fuel pressure of the low pressure accumulator 4 is made larger than that in the normal state (the valve opening time is made longer), and a large amount of fuel is supplied to the fuel tank 17.
The fuel pressure in the low-pressure accumulator 4 does not reach the set pressure unless it is discharged to. Therefore, the duty ratio (load) of the pressure control valve 34 increases.
【００３０】図１０は、低圧蓄圧器４の指示圧力と圧力
制御弁３４のデューティ比（負荷）の関係を示す。図１
０において、実線は、切換弁５が正常な状態における圧
力制御弁３４のデューティ比の基準値（理論開弁率）を
示し、その両側にデューティ比許容値（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、圧力制御弁３４のデューティ比が小さい
即ち、負荷が小さい領域、上側の領域IIIは、圧力制御
弁３４のデューティ比が大きい即ち、負荷が大きい領域
である。FIG. 10 shows the relationship between the indicated pressure of the low pressure accumulator 4 and the duty ratio (load) of the pressure control valve 34. Figure 1
At 0, the solid line indicates the reference value (theoretical valve opening rate) of the duty ratio of the pressure control valve 34 when the switching valve 5 is in a normal state, and the duty ratio allowable value (hysteresis) is on both sides thereof.
Is set as the reference area I. The lower region II of the reference region I is a region where the duty ratio of the pressure control valve 34 is small, that is, the load is small, and the upper region III is a region where the duty ratio of the pressure control valve 34 is large, that is, the load is large. .
【００３１】電子制御装置８は、圧力制御弁３４のデュ
ーティ比（負荷）をモニタして、図１０の基準領域Ｉを
逸脱した領域IIにある場合には切換弁５が閉弁状態で故
障しているものと判定し、領域IIIにある場合には切換
弁５が開弁状態で故障しているものと判定する。切換弁
５の故障としては、高圧燃料に晒されることに起因する
スプールのスティック等の機械的な故障と、ソレノイド
の断線による電気的な故障がある。また、他にオリフィ
ス６ａの詰まり等に起因する故障もある。切換弁５のソ
レノイドが断線している場合には、電子制御装置８は、
断線判定により切換弁５の故障を判定する。The electronic control unit 8 monitors the duty ratio (load) of the pressure control valve 34, and when it is in the region II deviating from the reference region I in FIG. 10, the switching valve 5 fails in the closed state. If it is in the region III, it is determined that the switching valve 5 is open and is out of order. Failures of the switching valve 5 include mechanical failures such as spool sticks due to exposure to high-pressure fuel, and electrical failures due to disconnection of solenoids. In addition, there is a failure due to clogging of the orifice 6a. When the solenoid of the switching valve 5 is disconnected, the electronic control unit 8
A failure of the switching valve 5 is determined by the disconnection determination.
【００３２】電子制御装置８は、図９のステップＳ３の
切換弁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、インジェクタ９及び燃料
噴射率を切り換え制御する切換弁５の各制御マップを故
障モード用に切り換えて制御する。即ち、図１１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）に対して最大噴射量・エンジンの最高回転数
（最大値）を制限する。図１１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 electronic control unit 8 of the switching valve 5 for switching and controlling the fuel injection amount, the injection pressure, the injector 9 and the fuel injection rate in the failure control mode (limp home mode) of the switching valve in step S3 of FIG. Each control map is switched for the failure mode and controlled. That is, as shown by the solid line in FIG. 11, the fuel injection amount control limits the maximum injection amount and the maximum engine speed (maximum value) with respect to the normal mode (maximum value) shown by the dotted line. FIG. 11 is a characteristic diagram showing the relationship between the engine speed and the fuel injection amount.
【００３３】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と低圧蓄圧器４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、最大圧力が点線で示す通常制御時におけ
る高圧蓄圧器４の燃料圧よりも低く、通常制御時におけ
る低圧蓄圧器４の燃料圧よりも高く、且つ低圧蓄圧器４
の許容耐圧（許容圧力）以下とされている。この設定圧
は、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高圧蓄圧器３の燃料圧
を制御すると共に、圧力制御弁３４のデューティ比を制
御して低圧蓄圧器４の燃料圧を制御し、これら高圧蓄圧
器３と低圧蓄圧器４の燃料圧が同一となるように制御す
る。このように高圧蓄圧器３の最大圧力（燃料圧）を低
圧蓄圧器４の許容耐圧以下とすることで、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の各燃料圧と
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 and the low pressure accumulator 4 to a predetermined pressure (hereinafter referred to as "set pressure") as shown by the solid line in FIG.
This set pressure is lower than the fuel pressure of the high pressure accumulator 4 at the time of normal control whose maximum pressure is indicated by the dotted line, higher than the fuel pressure of the low pressure accumulator 4 at the time of normal control, and low pressure accumulator 4
Is less than the allowable withstand pressure (allowable pressure) of. This set pressure controls the fuel pressure of the high pressure accumulator 3 by adjusting the effective section of the pressure feeding stroke of the plunger 21 (FIG. 1) of the high pressure fuel pump 1, and controls the duty ratio of the pressure control valve 34 to reduce the low pressure. The fuel pressure of the pressure accumulator 4 is controlled so that the high pressure accumulator 3 and the low pressure accumulator 4 have the same fuel pressure. In this way, by setting the maximum pressure (fuel pressure) of the high pressure accumulator 3 to be equal to or lower than the allowable withstand pressure of the low pressure accumulator 4, the low pressure accumulator 4
The damage of fuel and fuel leakage are prevented. FIG. 12 is a characteristic diagram showing the relationship between the engine speed and the fuel pressures of the high pressure accumulator 3 and the low pressure accumulator 4.
【００３４】このように高圧蓄圧器３の最大圧力（燃料
圧）を低圧蓄圧器４の許容耐圧以下とすることで、切換
弁５が故障した気筒と、切換弁５が正常な他の気筒の燃
料噴射圧が同一となり、気筒間のトルク差が無くなり、
トルク変動が抑制され、エンジン振動が抑制される。図
８は、切換弁５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。図８に示すように、インジェクタ９の開
弁時期即ち、噴射時期を制御する開閉弁７の制御は、通
常制御と同一のマップを使用して制御の簡略化を図る。
また、正常な切換弁５の開弁時期は、インジェクタ９の
開弁時期（開閉弁７の開弁時期）よりも進め（進角）に
設定する。これにより、切換弁５の閉弁故障時には高圧
蓄圧器３の燃料圧（ＰHP）＝低圧蓄圧器４の燃料圧（Ｐ
LP）に制御している状態であるから、切換弁５が閉弁故
障している気筒は、他の切換弁５が正常な気筒と同一圧
力の燃料を低圧蓄圧器４から供給されて、全気筒の噴射
波形を揃えることができる。また、或る切換弁５が開弁
故障時には、他の切換弁５が正常な気筒は、全噴射期間
中に亘って切換弁５が開弁していることになり、前記切
換弁５が開弁故障している気筒と同じ条件となるため、
全気筒の噴射波形を揃えることができる。By setting the maximum pressure (fuel pressure) of the high-pressure accumulator 3 to be equal to or lower than the allowable withstand pressure of the low-pressure accumulator 4 in this way, a cylinder in which the switching valve 5 has failed and another cylinder in which the switching valve 5 is normal Fuel injection pressure becomes the same, torque difference between cylinders disappears,
Torque fluctuation is suppressed and engine vibration is suppressed. FIG. 8 shows a fuel injection waveform in the failure mode of the switching valve 5,
The timing chart which shows the drive of the injector 9 and the switching valve 5 is shown. As shown in FIG. 8, the valve opening timing of the injector 9, that is, the control of the opening / closing valve 7 that controls the injection timing uses the same map as the normal control to simplify the control.
Further, the normal valve opening timing of the switching valve 5 is set (advanced) ahead of the valve opening timing of the injector 9 (valve opening timing of the opening / closing valve 7). As a result, when the switching valve 5 fails to close, the fuel pressure in the high pressure accumulator 3 (P HP ) = the fuel pressure in the low pressure accumulator 4 (P HP ).
Since the control valve is in the state of being controlled to LP ), the cylinder whose switching valve 5 has a valve closing failure is supplied with fuel of the same pressure as that of the normal cylinder of the other switching valve 5 from the low pressure accumulator 4, and The injection waveforms of the cylinders can be made uniform. Further, when a certain switching valve 5 fails to open, the switching valve 5 is opened in the cylinder in which the other switching valve 5 is normal, and the switching valve 5 is opened during the entire injection period. Because the same condition as the cylinder with valve failure,
The injection waveforms of all cylinders can be made uniform.
【００３５】このように、電子制御装置８により燃料噴
射率を切り換える切換弁５の故障を判定し、故障時には
リンプホームモードに設定することで、エンジン本体の
損傷、ひいてはエンジン本体の過負荷、排気温度の上昇
等に伴う車両の損傷を回避することができる。また、切
換弁故障時には、リンプホームモードで適正な制御を行
うことで、エンジンの過負荷運転、回転変動等を抑制し
て、修理工場まで自走することが可能となる。As described above, the electronic control unit 8 determines the failure of the switching valve 5 for switching the fuel injection rate, and when the failure occurs, the limp home mode is set, thereby damaging the engine body and eventually overloading the engine body or exhausting the engine. It is possible to avoid damage to the vehicle due to a rise in temperature. Further, when the switching valve fails, proper control is performed in the limp home mode, so that it is possible to suppress engine overload operation, rotation fluctuation, etc., and to self-propell to the repair shop.
【００３６】また、低圧蓄圧器４の圧力を制御する圧力
制御弁３４が故障した場合、閉弁故障時には低圧蓄圧器
４の燃料圧が上昇し、最終的には高圧蓄圧器３の燃料圧
と等しくなる。圧力制御弁３４が閉弁状態で故障した場
合の噴射波形は、図１３に示すように圧力制御弁３４が
正常な場合（点線で示す）に対して噴射初期から高圧噴
射のみの異常な噴射となる。従って、燃料噴射量が増大
して過負荷運転となるため、このままの異常な状態でエ
ンジン運転を続けると、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４は、高圧蓄圧
器３に対して、許容耐圧が低く設定されているため、低
圧蓄圧器４内の燃料圧の過度な圧力上昇は、低圧蓄圧器
４の損傷、燃料漏れ等を来す虞がある。図１３は、圧力
制御弁３４が閉弁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。When the pressure control valve 34 for controlling the pressure of the low pressure accumulator 4 fails, the fuel pressure of the low pressure accumulator 4 rises at the time of valve closing failure, and finally the fuel pressure of the high pressure accumulator 3 becomes the same. Will be equal. When the pressure control valve 34 fails in the closed state, the injection waveform is an abnormal injection from the initial injection to high pressure injection as compared to when the pressure control valve 34 is normal (shown by the dotted line). Become. Therefore, the fuel injection amount increases and the engine is overloaded. Therefore, if the engine operation is continued under such an abnormal condition, the engine and eventually the vehicle may be damaged. Further, the low-pressure accumulator 4 is set to have a lower allowable withstand voltage than the high-pressure accumulator 3, so that an excessive increase in fuel pressure in the low-pressure accumulator 4 causes damage to the low-pressure accumulator 4 and fuel leakage. And so on. FIG. 13 is a fuel injection waveform when the pressure control valve 34 fails in the closed state,
The timing chart which shows the drive of the injector 9 and the switching valve 5 is shown.
【００３７】圧力制御弁３４が開弁故障時には、低圧噴
射が不可能となり、噴射波形は、図１４に示すように切
換弁が正常な気筒の噴射波形（点線で示す）に対して低
圧噴射（初期噴射）が行われない高圧噴射（主噴射）の
みの波形となる。このため、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。また、低圧蓄圧器４の圧力を上げようとするため、
高圧燃料ポンプ１が過剰な燃料圧送を繰り返し、当該高
圧燃料ポンプ１の故障を招く虞がある。図１４は、圧力
制御弁３４が開弁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。When the pressure control valve 34 fails to open, low-pressure injection becomes impossible, and the injection waveform is low-pressure injection (indicated by the dotted line) with respect to the injection waveform of the cylinder in which the switching valve is normal as shown in FIG. The waveform is only for the high-pressure injection (main injection) where the initial injection is not performed. Therefore, the ignition timing is delayed, the exhaust temperature rises, the torque becomes insufficient, and the engine is adversely affected. Also, in order to increase the pressure of the low pressure accumulator 4,
There is a possibility that the high-pressure fuel pump 1 may repeatedly feed the excessive amount of fuel, resulting in failure of the high-pressure fuel pump 1. FIG. 14 is a fuel injection waveform when the pressure control valve 34 fails in the open state,
The timing chart which shows the drive of the injector 9 and the switching valve 5 is shown.
【００３８】このように圧力制御弁３４が閉弁状態又は
開弁状態の何れの状態で故障した場合でも、低圧噴射と
高圧噴射の組合せができなくなり、圧力制御弁３４が正
常な場合に対して噴射量が異常となる。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１５
に示す低圧蓄圧器の圧力制御弁故障判定ルーチンを所定
周期で実行する。この判定ルーチンにおいて、低圧蓄圧
器４の燃圧を制御する圧力制御弁３４が正常か否かを判
定し（ステップＳ１１）、正常であるときには通常制御
モードに移行し（ステップＳ１２）、故障しているとき
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Ｓ１３）。In this way, even if the pressure control valve 34 fails in either the closed state or the open state, the combination of the low pressure injection and the high pressure injection cannot be performed, and the pressure control valve 34 is normal. The injection amount becomes abnormal. Therefore, in the pressure-accumulation type fuel injection device of the present invention, the electronic control unit 8 is configured as shown in FIG.
The pressure control valve failure determination routine of the low pressure accumulator shown in is executed at a predetermined cycle. In this determination routine, it is determined whether or not the pressure control valve 34 that controls the fuel pressure of the low-pressure accumulator 4 is normal (step S11), and if normal, the normal control mode is entered (step S12) and there is a failure. At times, the control mode shifts to the failure control mode (limp home mode) (step S13).
【００３９】ステップＳ１１における圧力制御弁３４の
故障判定は、電子制御装置８により、低圧蓄圧器４の燃
料圧を検出する圧力センサ４ａが検出した実圧力と電子
制御装置８による指示圧力との、或る一定値以上の差圧
が継続する時間をモニタして判定する。この圧力制御弁
３４の故障判定は、閉弁状態で故障している場合と、開
弁状態で故障している場合との２通りを判定する。The failure determination of the pressure control valve 34 in step S11 is performed by the electronic control unit 8 based on the actual pressure detected by the pressure sensor 4a for detecting the fuel pressure of the low pressure accumulator 4 and the instruction pressure by the electronic control unit 8. It is determined by monitoring the time during which the differential pressure over a certain value continues. The failure determination of the pressure control valve 34 is made in two ways, that is, the failure in the closed state and the failure in the open state.
【００４０】圧力制御弁３４が閉弁状態で故障した場合
には、燃料通路１０ａから低圧蓄圧器４に供給された高
圧燃料が、燃料タンク７側（大気開放側）に排出されな
いために、当該低圧蓄圧器４内の燃料圧が高くなる。電
子制御装置８は、圧力センサ４ａが検出した低圧蓄圧器
４の（実圧力）が（指示圧力＋α）よりも高い状態（実
圧力＞指示圧力＋α）が一定時間以上継続した場合に
は、圧力制御弁３４が閉弁状態で故障したと判定する。
一定時間は、圧力差を正確にモニタするための追従時間
である。When the pressure control valve 34 fails in the closed state, the high-pressure fuel supplied from the fuel passage 10a to the low-pressure accumulator 4 is not discharged to the fuel tank 7 side (atmosphere opening side). The fuel pressure in the low pressure accumulator 4 becomes high. If the state (actual pressure> indicated pressure + α) of the low pressure accumulator 4 detected by the pressure sensor 4a is higher than (indicated pressure + α) for a certain time or longer, the electronic control unit 8 determines the pressure. It is determined that the control valve 34 has failed in the closed state.
The fixed time is a follow-up time for accurately monitoring the pressure difference.
【００４１】また、圧力制御弁３４が開弁状態で故障し
た場合には、燃料通路１０ａから低圧蓄圧器４に供給さ
れた高圧燃料が、燃料タンク７側（大気開放側）に全て
排出されてしまうために、当該低圧蓄圧器４内の燃料圧
が低くなる。電子制御装置８は、圧力センサ４ａが検出
した低圧蓄圧器４の（実圧力）が（指示圧力−α）より
も低い状態（実圧力＜指示圧力−α）が一定時間以上継
続した場合には、圧力制御弁３４が開弁状態で故障した
と判定する。When the pressure control valve 34 fails in the open state, the high pressure fuel supplied from the fuel passage 10a to the low pressure accumulator 4 is completely discharged to the fuel tank 7 side (atmosphere open side). Therefore, the fuel pressure in the low pressure accumulator 4 becomes low. When the (actual pressure) of the low pressure accumulator 4 detected by the pressure sensor 4a is lower than the (indicated pressure-α) (actual pressure <indicated pressure-α) continues for a certain time or longer, the electronic control unit 8 , It is determined that the pressure control valve 34 is open and has failed.
【００４２】図１６は、低圧蓄圧器４の指示圧力と圧力
センサ４ａの出力（実圧力）との関係を示す。図１６に
おいて、実線は、圧力制御弁３４が正常な状態基準値を
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Ｖの下側の領域VI
は、実圧力が指示圧力よりも小さい領域、上側の領域VI
Iは、実圧力が指示圧力よりも大きい領域である。FIG. 16 shows the relationship between the indicated pressure of the low pressure accumulator 4 and the output (actual pressure) of the pressure sensor 4a. In FIG. 16, the solid line indicates the reference value of the normal state of the pressure control valve 34, and the allowable value (hysteresis) is set on both sides of the reference value to define the reference region I. Area VI below the reference area V
Is the area where the actual pressure is smaller than the indicated pressure, the upper area VI
I is a region where the actual pressure is larger than the indicated pressure.
【００４３】電子制御装置８は、実圧力と指示圧力（設
定圧）とをモニタして図１６の基準領域Ｖを逸脱した領
域VIにある場合には圧力制御弁３４が開弁状態で故障し
ているものと判定し、領域VIIにある場合には圧力制御
弁３４が閉弁状態で故障しているものと判定する。圧力
制御弁３４の故障としては、スプールのスティック等の
機械的な故障と、ソレノイドの断線による電気的な故障
がある。圧力制御弁３４のソレノイドが断線している場
合には、電子制御装置８は、断線判定により圧力制御弁
３４の故障を判定する。The electronic control unit 8 monitors the actual pressure and the indicated pressure (set pressure), and when it is in the region VI deviating from the reference region V in FIG. 16, the pressure control valve 34 fails in the open state. If the pressure control valve 34 is in the region VII, it is determined that the pressure control valve 34 is closed and malfunctions. Failures of the pressure control valve 34 include mechanical failures such as spool sticks and electrical failures due to disconnection of solenoids. When the solenoid of the pressure control valve 34 is disconnected, the electronic control unit 8 determines the failure of the pressure control valve 34 by the disconnection determination.
【００４４】電子制御装置８は、図１５のステップＳ１
３の圧力制御弁３４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、インジェク
タ９及び燃料噴射率を切り換え制御する切換弁５の各制
御マップを故障モード用に切り換えて制御する。即ち、
図１１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）に対して最大噴射量・エンジン
の最高回転数（最大値）を制限する。The electronic control unit 8 operates in step S1 of FIG.
In the failure control mode (limp home mode) of the pressure control valve 34 of No. 3, each control map of the switching valve 5 for switching and controlling the fuel injection amount, the injection pressure, the injector 9 and the fuel injection rate is switched for the failure mode and controlled. To do. That is,
As shown by the solid line in FIG. 11, the fuel injection amount control limits the maximum injection amount and the maximum engine speed (maximum value) with respect to the normal mode (maximum value) shown by the dotted line.
【００４５】更に、電子制御装置８は、前述した切換弁
５の故障時と同様に、図１２に実線で示すように高圧蓄
圧器３と低圧蓄圧器４の燃料圧を所定の設定圧に制御す
る。この設定圧は、最大圧力が点線で示す通常制御時に
おける高圧蓄圧器４の燃料圧よりも低く、通常制御時に
おける低圧蓄圧器４の燃料圧よりも高く、且つ低圧蓄圧
器４の許容耐圧（許容圧力）以下とすることで、圧力制
御弁３４が故障した場合に低圧蓄圧器の損傷や、燃料漏
れ等が防止される。この設定圧は、高圧燃料ポンプ１
（図１）のプランジャ２１の圧送ストロークの有効区間
を調整して高圧蓄圧器３の圧力（燃圧）を制御する。こ
れにより圧力制御弁３４が閉弁故障した場合には高圧蓄
圧器３と低圧蓄圧器４の圧力が同一となる。また、圧力
制御弁３４が開弁故障した場合は、高圧蓄圧器３のみが
所定圧となり、低圧蓄圧器４は、設定圧よりも低い値、
例えば、殆ど大気圧に近い圧力となる。Further, the electronic control unit 8 controls the fuel pressure of the high pressure accumulator 3 and the low pressure accumulator 4 to a predetermined set pressure as shown by the solid line in FIG. 12, as in the case of the failure of the switching valve 5 described above. To do. This set pressure is lower than the fuel pressure of the high pressure accumulator 4 at the time of normal control, in which the maximum pressure is indicated by the dotted line, higher than the fuel pressure of the low pressure accumulator 4 at the time of normal control, and the allowable pressure resistance of the low pressure accumulator 4 ( When the pressure control valve 34 fails, damage to the low pressure accumulator, fuel leakage, etc. can be prevented by setting the pressure to be equal to or lower than the allowable pressure). This set pressure is the high pressure fuel pump 1
The pressure (fuel pressure) of the high-pressure accumulator 3 is controlled by adjusting the effective section of the pressure feed stroke of the plunger 21 (FIG. 1). Thus, when the pressure control valve 34 fails to close, the pressures of the high pressure accumulator 3 and the low pressure accumulator 4 become the same. When the pressure control valve 34 fails to open, only the high pressure accumulator 3 has a predetermined pressure, and the low pressure accumulator 4 has a value lower than the set pressure.
For example, the pressure is close to atmospheric pressure.
【００４６】圧力制御弁３４の故障モード時におけるイ
ンジェクタ９及び切換弁５の駆動は、前述した切換弁５
の１つ（切換弁５-1）が故障した場合と同様に行う。即
ち、図８に示すように、インジェクタ９の開弁時期即
ち、噴射時期を制御する開閉弁７の制御は、通常制御と
同一のマップを使用して制御の簡略化を図る。また、切
換弁５の開弁時期は、インジェクタ９の開弁時期（開閉
弁７の開弁時期）よりも進める方向（進角）に設定す
る。これにより圧力制御弁３４の閉弁故障時、開弁故障
時の何れの場合も、インジェクタ９の開弁時期に燃料噴
射を開始することができる。従って、高圧蓄圧器３の圧
力の抑制（且つ、圧力制御弁３４の閉弁故障時には高圧
蓄圧器３の燃料圧（ＰHP）＝低圧蓄圧器４の燃料圧（Ｐ
LP）に制御）との組合せにより、圧力制御弁３４の閉弁
故障時には、過剰噴射量を防止し、開弁故障時には、噴
射時期の遅れを防止する。When the pressure control valve 34 is in the failure mode, the injector 9 and the switching valve 5 are driven by the switching valve 5 described above.
No. 1 (switching valve 5-1) fails in the same manner. That is, as shown in FIG. 8, the control of the opening / closing valve 7 for controlling the valve opening timing of the injector 9, that is, the injection timing, uses the same map as the normal control to simplify the control. In addition, the valve opening timing of the switching valve 5 is set in a direction (advance angle) that is ahead of the valve opening timing of the injector 9 (valve opening timing of the opening / closing valve 7). As a result, fuel injection can be started at the valve opening timing of the injector 9 regardless of whether the pressure control valve 34 has a valve closing failure or a valve opening failure. Therefore, the pressure of the high-pressure accumulator 3 is suppressed (and the fuel pressure (P HP ) of the high-pressure accumulator 3 is equal to the fuel pressure (P HP of the low-pressure accumulator 4 when the pressure control valve 34 is closed).
LP ) controls the excessive injection amount when the pressure control valve 34 fails to close, and prevents the injection timing from delaying when the valve fails to open.
【００４７】このように、電子制御装置８により低圧蓄
圧器４の圧力を制御する圧力制御弁３４の故障を判定
し、故障時にはリンプホームモードに設定することで、
エンジン本体の損傷、ひいてはエンジン本体の過負荷運
転、排気温度の上昇等に伴う車両の損傷を回避すること
ができる。また、圧力制御弁３４の故障時には、リンプ
ホームモードで適正な制御を行うことで、エンジンの過
負荷運転、回転変動等を抑制して、修理工場まで自走す
ることが可能となる。As described above, the electronic control unit 8 determines the failure of the pressure control valve 34 for controlling the pressure of the low pressure accumulator 4 and sets the limp home mode when the failure occurs.
It is possible to avoid damage to the engine body, and eventually damage to the vehicle due to overload operation of the engine body, rise in exhaust temperature, and the like. Further, when the pressure control valve 34 is out of order, proper control is performed in the limp home mode, thereby suppressing engine overload operation, rotation fluctuation, etc., and enabling self-propelled operation to a repair shop.
【００４８】[0048]
【発明の効果】本発明によれば、請求項１の発明では、
第１制御弁が閉弁状態で故障した場合には、故障した第
１制御弁に対応した気筒の高圧噴射が行われないが、正
常な第１制御弁から吐出される燃料圧（高圧燃料ポンプ
により圧力制御）を第２蓄圧器許容圧力以下のある燃料
圧とすることで、燃料通路内は、常に第２蓄圧器許容圧
力以下のある燃料圧に維持され、故障した第１制御弁に
対応した気筒においても噴射ノズルの開弁時から許容圧
噴射が可能となる。According to the present invention, in the invention of claim 1,
When the first control valve fails in the closed state, the high pressure injection of the cylinder corresponding to the failed first control valve is not performed, but the fuel pressure discharged from the normal first control valve (high pressure fuel pump Pressure control) to a fuel pressure that is less than or equal to the second accumulator allowable pressure, so that the fuel pressure in the fuel passage is always maintained at a fuel pressure that is less than or equal to the second accumulator allowable pressure and corresponds to the failed first control valve. Even in the above cylinder, the allowable pressure injection becomes possible after the injection nozzle is opened.
【００４９】また、第１制御弁が開弁状態で故障した場
合には、全気筒で高圧噴射のみが行われてしまい、第２
蓄圧器に許容圧以上の圧力がかかってしまうが、それを
防ぐため高圧燃料ポンプにより第２蓄圧器の許容圧以下
の燃料噴射が供給される。また、第２制御弁が閉弁状態
で故障した場合には、第２蓄圧器の燃料を制御できず、
高圧となってしまうが、それを防ぐため高圧燃料ポンプ
により第２蓄圧器の許容圧以下の燃料噴射が供給され
る。これにより、エンジンの故障や車両の損傷等を未然
に防止することができる。When the first control valve fails in the open state, only high pressure injection is performed in all cylinders, and the second control valve is used.
The pressure higher than the allowable pressure is applied to the pressure accumulator, but in order to prevent this, the high-pressure fuel pump supplies the fuel injection below the allowable pressure of the second pressure accumulator. Further, when the second control valve fails in the closed state, the fuel in the second pressure accumulator cannot be controlled,
Although the pressure becomes high, in order to prevent this, the high-pressure fuel pump supplies fuel injection at a pressure equal to or lower than the allowable pressure of the second pressure accumulator. As a result, engine failure, vehicle damage, etc. can be prevented in advance.
【００５０】請求項２の発明では、第２制御弁が開弁状
態で故障した場合には、全気筒で高圧噴射のみが行われ
てしまい、第２蓄圧器に許容圧以上の圧力がかかってし
まうが、それを防ぐため高圧燃料ポンプにより第２蓄圧
器の許容圧以下の燃料噴射が供給される。また、第２制
御弁が閉弁状態で故障した場合には、第２蓄圧器の燃料
を制御することができず高圧となってしまうが、それを
防ぐため高圧燃料ポンプにより第２蓄圧器の許容圧以下
の燃料噴射が供給される。これにより、エンジンの故障
や車両の損傷等を未然に防止することができる。請求項
３の発明では、制御手段は、複数の第１制御弁の少なく
とも１つが開弁状態で故障したときには、燃料ポンプの
吐出圧を第２蓄圧器の許容圧以下に設定すると共に、故
障した第１制御弁以外の正常な第１制御弁の開弁時間を
燃料噴射ノズルの開弁時期より前に設定する。これによ
り、第１制御弁が故障した気筒と、第１制御弁が正常な
他の気筒の燃料噴射圧が同一となる。即ち、第１制御弁
が正常な気筒は、全噴射期間中に亘って前記第１制御弁
が故障している気筒と同じ条件となり、全気筒の噴射波
形を揃えることができ、気筒間のトルク差がなくなり、
トルク変動が抑制されて、エンジン振動が抑制される。 According to the second aspect of the invention, when the second control valve fails in the open state, only high pressure injection is performed in all cylinders, and the second accumulator receives a pressure higher than the allowable pressure. However, in order to prevent this, the high-pressure fuel pump supplies fuel injection below the allowable pressure of the second pressure accumulator. Further, when the second control valve fails in the closed state, the fuel in the second pressure accumulator cannot be controlled and becomes high in pressure. To prevent this, the high pressure fuel pump is used to prevent the second pressure accumulator from operating. Fuel injection below the allowable pressure is supplied. As a result, engine failure, vehicle damage, etc. can be prevented in advance. In the invention of claim 3, the control means sets the discharge pressure of the fuel pump to be equal to or less than the allowable pressure of the second pressure accumulator and fails when at least one of the plurality of first control valves fails in the open state. The normal valve opening time of the first control valves other than the first control valve is set before the valve opening timing of the fuel injection nozzle. As a result, the fuel injection pressure of the cylinder in which the first control valve has failed becomes the same as that of the other cylinder in which the first control valve is normal. That is, the cylinder in which the first control valve is normal has the same condition as the cylinder in which the first control valve has failed over the entire injection period, and the injection waveforms of all the cylinders can be made uniform, and the torque between the cylinders can be reduced. There is no difference,
Torque fluctuation is suppressed and engine vibration is suppressed .
【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】切換弁が閉弁状態で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 the switching valve fails in a closed state.
【図７】切換弁が開弁状態で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. 7 is a timing chart showing driving of a fuel injection waveform, an injector, and a switching valve when the switching valve fails in an open state.
【図８】切換弁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. 8 is a fuel injection waveform in the failure mode of the switching valve,
It is a timing chart which shows the drive of an injector and a switching valve.
【図９】図１に示す蓄圧式燃料噴射装置の切換弁故障判
定ルーチンのフローチャートである。9 is a flowchart of a switching valve failure determination routine of the pressure accumulation type fuel injection device shown in FIG.
【図１０】低圧蓄圧器の指示圧力と圧力制御弁のデュー
ティ比（負荷）の関係を示す特性図である。FIG. 10 is a characteristic diagram showing the relationship between the instruction pressure of the low pressure accumulator and the duty ratio (load) of the pressure control valve.
【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.
【図１３】圧力制御弁が閉弁状態で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. 13 is a timing chart showing driving of a fuel injection waveform, an injector, and a switching valve when the pressure control valve fails in a closed state.
【図１４】圧力制御弁が開弁状態で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. 14 is a timing chart showing driving of a fuel injection waveform, injectors, and a switching valve when a pressure control valve fails in an open state.
【図１５】図１に示す蓄圧式燃料噴射装置の切換弁故障
判定ルーチンのフローチャートである。FIG. 15 is a flowchart of a switching valve failure determination routine of the pressure accumulation type fuel injection device shown in FIG.
【図１６】低圧蓄圧器の指示圧力と実圧力との関係を示
す特性図である。FIG. 16 is a characteristic diagram showing the relationship between the indicated pressure and the actual pressure of the low pressure accumulator.
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 63/00 Ｆ０２Ｍ 63/00 Ｃ (56)参考文献 特開 昭63−90658（ＪＰ，Ａ) 特開 平６−93936（ＪＰ，Ａ) 特開 平６−323220（ＪＰ，Ａ) 特開 平７−49067（ＪＰ，Ａ) 特開 平８−68368（ＪＰ，Ａ) 特開 平８−291777（ＪＰ，Ａ) 特開 平10−77892（ＪＰ，Ａ) 特開 平10−238431（ＪＰ，Ａ) 国際公開98／9068（ＷＯ，Ａ１) (58)調査した分野(Int.Cl.7，ＤＢ名) F02M 47/00 F02M 47/02 F02M 45/00 F02M 45/04 F02M 55/02 310 F02M 55/02 350 F02M 61/20 F02M 63/00 F02D 41/22 375 ─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 7 Identification code FI F02M 63/00 F02M 63/00 C (56) References JP-A-63-90658 (JP, A) JP-A-6-93936 ( JP, A) JP 6-323220 (JP, A) JP 7-49067 (JP, A) JP 8-68368 (JP, A) JP 8-291777 (JP, A) JP 10-77892 (JP, A) JP 10-238431 (JP, A) International Publication 98/9068 (WO, A1) (58) Fields investigated (Int.Cl. 7 , DB name) F02M 47/00 F02M 47/02 F02M 45/00 F02M 45/04 F02M 55/02 310 F02M 55/02 350 F02M 61/20 F02M 63/00 F02D 41/22 375
Claims (3)
を貯溜する第１蓄圧器と、 前記第１蓄圧器から各気筒に向かって延設される複数の
燃料通路と、 前記燃料通路端部に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複数の第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し、前記第
２蓄圧器内の燃料圧力を制御する第２制御弁と、 通常運転時に、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制御を行う
とともに、前記複数の第１制御弁の少なくとも１つが故
障したと判定したとき、又は前記第２制御弁が閉弁状態
で故障したと判定したときに、前記燃料ポンプの吐出圧
力を前記第２蓄圧器の許容圧力以下に設定する燃料制御
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, a plurality of fuel passages extending from the first pressure accumulator toward each cylinder, and the fuel passage end portion. And a plurality of first control valves connected to the fuel injection nozzle for injecting fuel into the combustion chamber of each cylinder, and for controlling the discharge of the high-pressure fuel in the first pressure accumulator located in each of the fuel passages to the downstream side of the fuel passage. A second pressure accumulator that stores a fuel at a pressure lower than that of the high pressure fuel in the first pressure accumulator and is connected to the fuel passage downstream of the first control valve via a branch passage; The fuel inside the container is discharged to the atmosphere open side,
2 a second control valve for controlling the fuel pressure in the pressure accumulator , and a valve for closing the fuel injection nozzle, which is opened during the valve opening period of the fuel injection nozzle during normal operation. In addition to performing control to close the first control valve, it is determined that at least one of the plurality of first control valves has failed, or that the second control valve has failed in a closed state. And a fuel control means for setting a discharge pressure of the fuel pump to be equal to or lower than an allowable pressure of the second pressure accumulator.
を貯溜する第１蓄圧器と、 前記第１蓄圧器から各気筒に向かって延設される複数の
燃料通路と、 前記燃料通路端部に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複数の第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し、前記第
２蓄圧器内の燃料圧力を制御する第２制御弁と、前記分岐通路の前記第２蓄圧器の上流側に 配設された絞
りと、 通常運転時に、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制御を行う
とともに、前記第２制御弁が開弁状態で故障したと判定
したときに、前記燃料ポンプの吐出圧力を前記第２蓄圧
器の許容圧力以下に設定し、且つ前記第１制御弁の開弁
時期を燃料噴射ノズルの開弁時期より前に設定する燃料
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 for storing high-pressure fuel pressurized by a fuel pump, a plurality of fuel passages extending from the first pressure accumulator toward each cylinder, and the fuel passage end portion. And a plurality of first control valves connected to the fuel injection nozzle for injecting fuel into the combustion chamber of each cylinder, and for controlling the discharge of the high-pressure fuel in the first pressure accumulator located in each of the fuel passages to the downstream side of the fuel passage. A second pressure accumulator that stores a fuel at a pressure lower than that of the high pressure fuel in the first pressure accumulator and is connected to the fuel passage downstream of the first control valve via a branch passage; The fuel inside the container is discharged to the atmosphere open side,
2 A second control valve for controlling the fuel pressure in the pressure accumulator, a throttle disposed in the branch passage on the upstream side of the second pressure accumulator, and in the middle of the valve opening period of the fuel injection nozzle during normal operation. The first control valve is opened and the first control valve is closed according to the closing of the fuel injection nozzle, and it is determined that the second control valve has failed in the open state. when the discharge pressure of the fuel pump is set to less than the allowable pressure of the second pressure accumulator, and fuel control means for the opening timing of the first control valve is set before the opening timing of the fuel injection nozzle An accumulator-type fuel injection device characterized by having.
を貯溜する第１蓄圧器と、 前記第１蓄圧器から各気筒に向かって延設される複数の
燃料通路と、 前記燃料通路端部に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複数の第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し、前記第
２蓄圧器内の燃料圧力を制御する第２制御弁と、 通常運転時に、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制御を行う
とともに、前記複数の第１制御弁の少なくとも１つが開
弁故障したと判定したとき、前記燃料ポンプの吐出圧力
を前記第２蓄圧器の許容圧力以下に設定すると共に故障
した第１制御弁以外の正常な第１制御弁の開弁時期を燃
料噴射ノズルの開弁時期より前に設定する燃料制御手段
と を有したことを特徴とする蓄圧式燃料噴射装置。 3. High pressure fuel pressurized by a fuel pump
A first pressure accumulator for storing a plurality of cylinders and a plurality of cylinders extending from the first pressure accumulator toward each cylinder.
A fuel passage and a fuel connected to the end of the fuel passage for introducing fuel into the combustion chamber of each cylinder.
Fuel injection nozzle for injecting, and high-pressure fuel in the first pressure accumulator arranged in each of the fuel passages
First control valves for controlling the discharge of fuel to the downstream side of the fuel passage
And stores fuel at a pressure lower than that of the high pressure fuel in the first pressure accumulator.
A branch passage is provided in the fuel passage downstream of the first control valve.
A second pressure accumulator connected through the second pressure accumulator, and the fuel in the second pressure accumulator is discharged to the atmosphere open side;
2 A second control valve for controlling the fuel pressure in the pressure accumulator, and during normal operation, during the valve opening period of the fuel injection nozzle.
The first control valve is opened, and the fuel injection nozzle
The control for closing the first control valve is performed according to the closing of the valve.
And at least one of the plurality of first control valves is opened.
When it is judged that the valve has failed, the discharge pressure of the fuel pump
Is set below the permissible pressure of the second pressure accumulator and
The normal opening timing of the 1st control valve other than the 1st control valve
Fuel control means set before the valve opening timing of the fuel injection nozzle
Accumulator fuel injection apparatus characterized by having and.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33573498A JP3377034B2 (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 |
|---|---|---|---|
| JP33573498A JP3377034B2 (en) | 1998-11-26 | 1998-11-26 | Accumulator type fuel injection device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000161171A JP2000161171A (en) | 2000-06-13 |
| JP3377034B2 true JP3377034B2 (en) | 2003-02-17 |
Family
ID=18291887
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33573498A Expired - Fee Related JP3377034B2 (en) | 1998-11-20 | 1998-11-26 | Accumulator type fuel injection device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3377034B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007182792A (en) * | 2006-01-05 | 2007-07-19 | Usui Kokusai Sangyo Kaisha Ltd | Common rail fuel injection system |
| JP4573218B2 (en) * | 2006-06-09 | 2010-11-04 | 株式会社デンソー | Fuel injection device |
| JP4868173B2 (en) * | 2008-02-07 | 2012-02-01 | 株式会社デンソー | Abnormality diagnosis device for internal combustion engine |
| JP2013079594A (en) | 2011-10-03 | 2013-05-02 | Usui Kokusai Sangyo Kaisha Ltd | Common rail type fuel injection system |
| JP5835117B2 (en) * | 2012-06-19 | 2015-12-24 | トヨタ自動車株式会社 | Fuel supply control device for internal combustion engine |
-
1998
- 1998-11-26 JP JP33573498A patent/JP3377034B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000161171A (en) | 2000-06-13 |
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