EP0910739B1 - Fuel injection system - Google Patents

Fuel injection system Download PDF

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Publication number
EP0910739B1
EP0910739B1 EP98912246A EP98912246A EP0910739B1 EP 0910739 B1 EP0910739 B1 EP 0910739B1 EP 98912246 A EP98912246 A EP 98912246A EP 98912246 A EP98912246 A EP 98912246A EP 0910739 B1 EP0910739 B1 EP 0910739B1
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EP
European Patent Office
Prior art keywords
injection
pump
cam
sub area
valve
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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 - Lifetime
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EP98912246A
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German (de)
French (fr)
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EP0910739A1 (en
Inventor
Stuart-William Nicol
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Robert Bosch GmbH
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Robert Bosch GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20—Varying fuel delivery in quantity or timing
    • F02M59/36—Varying fuel delivery in quantity or timing by variably-timed valves controlling fuel passages to pumping elements or overflow passages
    • F02M59/366—Valves being actuated electrically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M41/00—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor
    • F02M41/08—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor and pumping elements being combined
    • F02M41/10—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor and pumping elements being combined pump pistons acting as the distributor
    • F02M41/12—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor and pumping elements being combined pump pistons acting as the distributor the pistons rotating to act as the distributor
    • F02M41/123—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor and pumping elements being combined pump pistons acting as the distributor the pistons rotating to act as the distributor characterised by means for varying fuel delivery or injection timing
    • F02M41/125—Variably-timed valves controlling fuel passages
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
    • F02M45/02—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
    • F02M45/04—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
    • F02M45/06—Pumps peculiar thereto
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
    • F02M45/02—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
    • F02M45/04—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
    • F02M45/06—Pumps peculiar thereto
    • F02M45/063—Delivery stroke of piston being divided into two or more parts, e.g. by using specially shaped cams

Definitions

  • the invention is based on a fuel injection system the genus of claim 1.
  • a fuel injection pump a distributor injection pump is provided, with a back and forth driven and at the same time rotating pump piston which rotates during its and its pump stroke one of several injection lines, that each lead to a fuel injector Injection brought fuel supplied.
  • the electrically controlled Valve which is a solenoid valve, opened briefly, and so on relieve the pump workspace and the fuel pressure achieved dismantle briefly. This means that a very fast switching solenoid valve is required, the one considerable effort on the electrical control and on the Construction of the valve requires.
  • the solution according to the invention ensures a safe one Interruption of injection between pre-injection and main injection with low demands on speed of a time-controlled valve. Doing so during the interruption the injection between pre and Main injection no or only a very small part of the available cam stroke. Through the constructive Support the interruption of the Injection is achieved even at higher speeds a safe interruption of injection between pre and main injection is observable without it becoming a Loss of those available for high-pressure production Cam stroke is coming. The speed-independent influence of the switching time is through the second portion of the cam compensated, so that no overly large requirements the speed of the electrically controlled valve must be asked.
  • FIG. 1 shows a basic illustration of a Fuel injection pump controlled by a solenoid valve 2 shows a course of the invention Cam track in the form of a cam elevation curve over the angle of rotation with a first control sequence of the valve low speed of the internal combustion engine and Figure 3 a Course of the cam track according to the invention over the angle of rotation with a second control sequence of the valve at high Speed of the internal combustion engine.
  • Embodiment based on a distributor injection pump realized as shown schematically in Figure 1 is. It is a distributor injection pump the axial piston type, even if the object the invention also in other fuel injection pumps is usable such.
  • the invention is in a distributor injection pump feasible because here the available cam stroke because of the limited length of the cam track is smaller than e.g. an in-line injection pump.
  • a pump piston 1 is provided, which is displaceable and rotatable in a cylinder bore 2 is arranged and there on the front a pump work space 10 includes.
  • the pump piston is included a cam 6, the axially downward facing cam 5 of the embodiment according to the invention, for. B. about a spring, not shown, coupled.
  • the cam disc becomes rotating, especially synchronous to the speed the internal combustion engine supplied by the injection pump a drive shaft not shown in known Way driven, the cam disc under the influence of Spring on a known axially fixed roller ring expires and subsequently the rotating pump and Distributor piston in a reciprocating promotional and sucking movement offset.
  • the time or angle of rotation dependent The course of the rollers on the cam flank is determined thus the stroke position of the pump piston.
  • the pump piston When it rotates in association with a pump delivery stroke in which from the pump work space 10 fuel is displaced under high pressure, the pump piston comes with one of several injection lines 7 via a distributor groove 8 in the lateral surface of the Pump and distributor pistons in connection.
  • the distributor groove is constantly connected to the pump workspace via a longitudinal channel 9 connected.
  • the injection line introduces via Pressure valve 12 to a fuel injection valve 13, the assigned to the respective cylinder of an internal combustion engine is.
  • the pump work space 10 is supplied with fuel via a suction line 15, which is separated from a suction space 17, which is essentially only shown in dashed lines and enclosed within the housing of the fuel injection pump is supplied.
  • the suction chamber receives fuel from a fuel feed pump 18, which is synchronous with the fuel injection pump, e.g. B. driven by the drive shaft and therefore fuel in speed-dependent quantities promotes in the suction chamber.
  • a fuel feed pump 18 is usually the pressure in the suction chamber controlled speed-dependent, if with the help of this Pressure additional functions of the fuel injection pump controlled should be.
  • An overflow throttle 22 flows continuously Fuel back to the reservoir 23, so that for cooling the injection pump or degassing the Suction chamber is taken care of.
  • the suction line 15 leads through Check valve 16 in the pump work space, which Check valve opens towards the pump work area.
  • an electrically controlled one Valve 24 is provided which has a bypass line 21 controls to the pressure valve 16 and with its help when opening the valve a connection between the pump work space 10 and suction chamber 17 is made and when the valve is closed the pump work space 10 is closed. That as a solenoid valve symbolized electrically controlled valve 24 is controlled by a control device 25 according to operating parameters controlled in a manner known per se. With enough large flow cross section of the valve 24 can, however Check valve 16 is also omitted. In this case the Pump work space during the suction stroke only via the electrically controlled Valve filled.
  • the valve can also be used to control the start of spraying become.
  • the start of spraying through a separate injection start adjustment device be adjusted, which is known to be relative to the Cam-sensing pump piston rotatable cam drive part having.
  • the cam 5 designed so that it as in the Figure 2 or 3 shown a stroke over time of the pump piston, which is divided into one first area V which begins with the delivery stroke of the piston ends after a small delivery stroke, in a second area P in which the piston then not at all or only so slightly is moved in the conveying direction that he is in this area for high-pressure delivery is not effective and an injection break arises and finally into a third Area H in which the cam flank rises again and the Pump piston for further delivery of the main injection quantity moves further.
  • area P the cam can be horizontal, slightly rising or falling.
  • the pilot injection is continued by the electric controlled valve controlled so that it is closed is when the roles in the second area P come.
  • the diagram is in FIG. 2 shows that the electrically controlled valve, e.g. a solenoid valve or one from a piezo actuated valve, for controlling the start of the pre-injection quantity delivery in U.T., i.e. before the rise of Cam curve is closed from a base circle and in which Cam area V again before reaching cam area P. is opened.
  • the electrically controlled valve e.g. a solenoid valve or one from a piezo actuated valve
  • the electrically controlled valve e.g. a solenoid valve or one from a piezo actuated valve, for controlling the start of the pre-injection quantity delivery in U.T., i.e. before the rise of Cam curve is closed from a base circle and in which Cam area V again before reaching cam area P. is opened.
  • a spray break in area P follows then a reclosing of the valve 24 with the start of the high pressure delivery for the main injection in the following Cam flank part H, where thereafter by opening valve 24 the high-pressure
  • valve 24 becomes like this controlled that it is only in the region of the cam flank part P is closed so that it is securely closed when the Fuel delivery for the now main injection in the area of the cam flank part adjoining area P. H is done.
  • the end of the injection will turn controlled by opening the valve, which then usually even before the top dead center of the cam of the injection pumps he follows.
  • This control has the advantage that at high speeds the pump workspace of the injection pump is sufficient Fuel can be filled because the filling phase is now against is extended above the control at low speed and the piston movement in the filling direction, i.e. during the suction stroke only must reach the stroke range on which the second Area P is located. Because of the only starting from area P. High-pressure delivery is the required filling quantity of the pump working room reduced.
  • the electric The controlled valve therefore closes only in the region P Cam flank so that the suction stroke for sucking fuel fully exploited via the trailing cam flank V. can be.
  • the inflow filling effect still affects the beginning part of the cam flank in front of area P as long the valve is not yet closed.

Description

Stand der TechnikState of the art

Die Erfindung geht von einem Kraftstoffeinspritzsystem gemäß der Gattung des Patentanspruchs 1 aus. Bei einem solchen, durch die DE-A-36 44 257 bekannten System ist als Kraftstoffeinspritzpumpe eine Verteilereinspritzpumpe vorgesehen, mit einem hin- und hergehend angetriebenen und zugleich rotierenden Pumpenkolben, der bei seiner Drehbewegung und seinem Pumphub jeweils eine von mehreren Einspritzleitungen, die zu je einem Kraftstoffeinspritzventil führen, mit auf Einspritzdruck gebrachtem Kraftstoff versorgt. Zur Unterteilung der Einspritzung in eine Voreinspritzung und eine Haupteinspritzung wird das elektrisch gesteuerte Ventil, das ein Magnetventil ist, kurzzeitig geöffnet, um so den Pumpenarbeitsraum zu entlasten und den erzielten Kraftstoffdruck kurzzeitig abzubauen. Dies bedeutet, daß ein sehr schnell schaltendes Magnetventil erforderlich ist, das einen erheblichen Aufwand an die elektrische Steuerung und an die Konstruktion des Ventils erfordert. Besonders nachteilig ist dabei die Tatsache, daß die Unterbrechung der Einspritzung durch ein Magnetventil zeitgesteuert erfolgen muß. Dadurch wird mit zunehmender Drehzahl ein immer größer werdender Teil des verfügbaren Nockenhubes für die Unterbrechung der Einspritzung in Anspruch genommen. Bei einer Verteilereinspritzpumpe steht ein gegenüber den Möglichkeiten einer Reiheneinspritzpumpe, bei der ein Nocken allein jeweils einen Pumpenkolben antreibt ein wesentlich geringerer Hub pro Einispritzvorgang zur Verfügung, weil der hier verfügbare Nockenhub wegen der begrenzten Länge der Nockenbahn beschränkt ist. Eine zeitgesteuerte Unterbrechung der Einspritzung durch Zwischenentlastung des Pumpenarbeitsraumes mittels eines Magnetventils bedeutet daher eine wesentliche Einschränkung der durch die Kraftstoffeinspritzpumpe bereitgestellte Leistung. Weiterhin ist auch ein spezielles Druckventil in der Verbindung zwischen Pumpenarbeitsraum und Einspritzventil vorgesehen, das bei Kraftstoffhochdruckförderung zur Kraftstoffeinspritzdüse in Förderrichtung öffnet und bei Beendigung der Einspritzung schließt und das geeignet ist, Druckwellen zwischen dem Druckventil und dem Kraftstoffeinspritzventil abzubauen und in diesem Bereich einen angestrebten konstanten Standdruck während der Einspritzpausen zu halten. Vorteilhaft ist es bei einer unterteilten Kraftstoffeinspritzung mit einer Voreinspritzung und einer Haupteinspritzung pro Arbeitstakt des jeweiligen zu versorgenden Zylinders der Brennkraftmaschine für einen konstanten Standdruck in den Einspritzpausen zu sorgen.The invention is based on a fuel injection system the genus of claim 1. With such a known from DE-A-36 44 257 system is as a fuel injection pump a distributor injection pump is provided, with a back and forth driven and at the same time rotating pump piston which rotates during its and its pump stroke one of several injection lines, that each lead to a fuel injector Injection brought fuel supplied. For Subdivision of the injection into a pre-injection and a main injection is the electrically controlled Valve, which is a solenoid valve, opened briefly, and so on relieve the pump workspace and the fuel pressure achieved dismantle briefly. This means that a very fast switching solenoid valve is required, the one considerable effort on the electrical control and on the Construction of the valve requires. Is particularly disadvantageous thereby the fact that the interruption of injection must be time-controlled by a solenoid valve. Thereby becomes more and more with increasing speed Part of the available cam stroke for the interruption of the Injection used. With a distributor injection pump stands against the possibilities of an in-line injection pump, where one cam alone has one Pump piston drives a much smaller stroke per Injection process available because of the here available Cam stroke due to the limited length of the cam track is limited. A timed interruption of injection by temporarily relieving the pump workspace by means of a solenoid valve therefore means an essential one Restriction of the one provided by the fuel injection pump Power. There is also a special pressure valve in the connection between the pump workspace and the injection valve provided that at High pressure fuel delivery to the fuel injector in Delivery direction opens and at the end of the injection closes and that is suitable for pressure waves between the Remove the pressure valve and the fuel injection valve and in this area a desired constant pressure to hold during the injection breaks. It is advantageous with a divided fuel injection with a pre-injection and one main injection per work cycle of the respective cylinder of the internal combustion engine to be supplied for a constant stand pressure in the injection breaks to care.

Vorteile der ErfindungAdvantages of the invention

Durch die erfindungsgemäße Lösung erfolgt eine sichere Unterbrechung der Einspritzung zwischen Vor- und Haupteinspritzung bei geringen Anforderungen an die Schnelligkeit eines zeitgesteuerten Ventils. Dabei wird während der Unterbrechung der Einspritzung zwischen Vor- und Haupteinspritzung kein oder nur ein sehr geringe Teil des verfügbaren Nockenhubes in Anspruch genommen. Durch die konstruktiv über die Nockenform unterstütze Unterbrechung der Einspritzung wird erreicht, daß selbst bei höherer Drehzahl eine sichere Unterbrechung der Einspritzung zwischen Vor- und Haupteinspritzung einhaltbar ist, ohne, daß es zu einer Einbuße an für die Hochdruckförderung bereitstellbaren Nockenhub kommt. Der drehzahlunabhängige Einfluß der Schaltzeit wird durch den zweiten Teilbereich des Nocken kompensiert, so daß auch keine allzugroße Anforderungen an die Schnelligkeit des elektrisch gesteuerten Ventils gestellt werden müssen.The solution according to the invention ensures a safe one Interruption of injection between pre-injection and main injection with low demands on speed of a time-controlled valve. Doing so during the interruption the injection between pre and Main injection no or only a very small part of the available cam stroke. Through the constructive Support the interruption of the Injection is achieved even at higher speeds a safe interruption of injection between pre and main injection is observable without it becoming a Loss of those available for high-pressure production Cam stroke is coming. The speed-independent influence of the switching time is through the second portion of the cam compensated, so that no overly large requirements the speed of the electrically controlled valve must be asked.

Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dargestellt und wird in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 eine Prinzipdarstellung einer Kraftstoffeinspritzpumpe, die von einem Magnetventil gesteuert wird, Figur 2 einen Verlauf der erfindungsgemäßen Nockenbahn in Form einer Nockenerhebungskurve über den Drehwinkel mit einer ersten Steuerungssequenz des Ventils bei niedriger Drehzahl der Brennkraftmaschine und Figur 3 einen Verlauf der erfindungsgemäßen Nockenbahn über den Drehwinkel mit einer zweiten Steuerungssequenz des Ventils bei hoher Drehzahl der Brennkraftmaschine.An embodiment of the invention is in the drawing shown and is described in more detail in the following description explained. FIG. 1 shows a basic illustration of a Fuel injection pump controlled by a solenoid valve 2 shows a course of the invention Cam track in the form of a cam elevation curve over the angle of rotation with a first control sequence of the valve low speed of the internal combustion engine and Figure 3 a Course of the cam track according to the invention over the angle of rotation with a second control sequence of the valve at high Speed of the internal combustion engine.

Beschreibungdescription

Die erfindungsgemäße Lösung ist beim nachfolgend beschriebenen Ausführungsbeispiel anhand einer Verteilereinspritzpumpe realisiert, wie sie schematisch in der Figur 1 dargestellt ist. Es handelt sich dort um eine Verteilereinspritzpumpe der Axialkolbenbauart, wenn auch der Gegenstand der Erfindung auch bei anderen Kraftstoffeinspritzpumpen verwendbar ist, wie z. B. Verteilereinspritzpumpen der Radialkolbenpumpenbauart oder Einzelpumpen mit nur einem Pumpenkolben zur Versorgung eines einzelnen Zylinders einer Brennkraftmaschine oder Reihenpumpen. Besonders vorteilhaft ist die Erfindung aber bei einer Verteilereinspritzpumpe verwirklichbar, weil hier der verfügbare Nockenhub wegen der begrenzten Länge der Nockenbahn kleiner ist als bei z.B. einer Reiheneinpritzpumpe. Bei der Verteilereinspritzpumpe der in der Figur 1 gezeigten Art ist ein Pumpenkolben 1 vorgesehen, der in einer Zylinderbohrung 2 verschieb- und verdrehbar angeordnet ist und dort stirnseitig einen Pumpenarbeitsraum 10 einschließt. Der Pumpenkolben ist dabei mit einer Nockenscheibe 6, die axial nach unten weisende Nocken 5 der erfindungsgemäßen Ausgestaltung aufweist, z. B. über eine nicht weiter gezeigte Feder, gekoppelt. Die Nockenscheibe wird rotierend, insbesondere synchron zur Drehzahl der von der Einspritzpumpe versorgten Brennkraftmaschine von einer nicht weiter gezeigten Antriebswelle in bekannter Weise angetrieben, wobei die Nockenscheibe unter Einfluß der Feder auf einem bekannten axial feststehenden Rollenring abläuft und in der Folge den rotierenden Pumpen- und Verteilerkolben in eine hin- und hergehende fördernden und ansaugende Bewegung versetzt. Der zeitliche bzw. drehwinkelabhängige Ablauf der Rollen auf der Nockenflanke bestimmt also die Hublage des Pumpenkolbens. Bei seiner Drehbewegung in Zuordnung zu einem Pumpenförderhub, bei dem aus dem Pumpenarbeitsraum 10 Kraftstoff unter Hochdruck verdrängt wird, kommt der Pumpenkolben mit einer von mehreren Einspritzleitungen 7 über eine Verteilernut 8 in der Mantelfläche des Pump- und Verteilerkolbens in Verbindung. Die Verteilernut ist dabei über einen Längskanal 9 ständig mit dem Pumpenarbeitsraum verbunden. Die Einspritzleitung führt über ein Druckventil 12 zu einem Kraftstoffeinspritzventil 13, das dem jeweiligen Zylinder einer Brennkraftmaschine zugeordnet ist.The solution according to the invention is described below Embodiment based on a distributor injection pump realized as shown schematically in Figure 1 is. It is a distributor injection pump the axial piston type, even if the object the invention also in other fuel injection pumps is usable such. B. radial piston pump type injection pumps or single pumps with only one pump piston to supply a single cylinder Internal combustion engine or in-line pumps. Particularly advantageous However, the invention is in a distributor injection pump feasible because here the available cam stroke because of the limited length of the cam track is smaller than e.g. an in-line injection pump. With the distributor injection pump of the type shown in FIG. 1, a pump piston 1 is provided, which is displaceable and rotatable in a cylinder bore 2 is arranged and there on the front a pump work space 10 includes. The pump piston is included a cam 6, the axially downward facing cam 5 of the embodiment according to the invention, for. B. about a spring, not shown, coupled. The cam disc becomes rotating, especially synchronous to the speed the internal combustion engine supplied by the injection pump a drive shaft not shown in known Way driven, the cam disc under the influence of Spring on a known axially fixed roller ring expires and subsequently the rotating pump and Distributor piston in a reciprocating promotional and sucking movement offset. The time or angle of rotation dependent The course of the rollers on the cam flank is determined thus the stroke position of the pump piston. When it rotates in association with a pump delivery stroke in which from the pump work space 10 fuel is displaced under high pressure, the pump piston comes with one of several injection lines 7 via a distributor groove 8 in the lateral surface of the Pump and distributor pistons in connection. The distributor groove is constantly connected to the pump workspace via a longitudinal channel 9 connected. The injection line introduces via Pressure valve 12 to a fuel injection valve 13, the assigned to the respective cylinder of an internal combustion engine is.

Die Versorgung des Pumpenarbeitsraumes 10 mit Kraftstoff erfolgt über eine Saugleitung 15, die von einem Saugraum 17, der im wesentlichen nur noch gestrichelt dargestellt ist und innerhalb des Gehäuses der Kraftstoffeinspritzpumpe eingeschlossen ist, versorgt. Der Saugraum erhält Kraftstoff von einer Kraftstofförderpumpe 18, die synchron zur Kraftstoffeinspritzpumpe, z. B. von der Antriebswelle her, angetrieben wird und somit Kraftstoff in drehzahlabhängigen Mengen in den Saugraum fördert. Mit Hilfe eines zusätzlichen Drucksteuerventils 19 wird der Druck im Saugraum üblicherweise drehzahlabhängig gesteuert, wenn mit Hilfe dieses Drucks Zusatzfunktionen der Kraftstoffeinspritzpumpe gesteuert werden sollen. Über eine Überlaufdrossel 22 fließt beständig Kraftstoff zum Vorratsbehälter 23 zurück, so daß dadurch für Kühlung der Einspritzpumpe bzw. Entgasung des Saugraumes gesorgt ist. Die Saugleitung 15 führt über ein Rückschlagventil 16 in den Pumpenarbeitsraum, wobei das Rückschlagventil in Richtung Pumpenarbeitsraum öffnet. Parallel zu diesem Rückschlagventil ist ein elektrisch gesteuertes Ventil 24 vorgesehen, das eine Bypassleitung 21 zum Druckventil 16 steuert und mit dessen Hilfe beim Öffnen des Ventils eine Verbindung zwischen Pumpenarbeitsraum 10 und Saugraum 17 hergestellt ist und beim Schließen des Ventils der Pumpenarbeitsraum 10 verschlossen ist. Das als Magnetventil symbolisierte elektrisch gesteuerte Ventil 24 wird von einer Steuereinrichtung 25 entsprechend Betriebsparametern in an sich bekannter Weise gesteuert. Bei genügend großem Durchflußquerschnitt des Ventils 24 kann jedoch das Rückschlagventil 16 auch entfallen. In diesem Falle wird der Pumpenarbeitsraum beim Saughub ausschließlich über das elektrischgesteuerte Ventil gefüllt.The pump work space 10 is supplied with fuel via a suction line 15, which is separated from a suction space 17, which is essentially only shown in dashed lines and enclosed within the housing of the fuel injection pump is supplied. The suction chamber receives fuel from a fuel feed pump 18, which is synchronous with the fuel injection pump, e.g. B. driven by the drive shaft and therefore fuel in speed-dependent quantities promotes in the suction chamber. With the help of an additional Pressure control valve 19 is usually the pressure in the suction chamber controlled speed-dependent, if with the help of this Pressure additional functions of the fuel injection pump controlled should be. An overflow throttle 22 flows continuously Fuel back to the reservoir 23, so that for cooling the injection pump or degassing the Suction chamber is taken care of. The suction line 15 leads through Check valve 16 in the pump work space, which Check valve opens towards the pump work area. In parallel to this check valve is an electrically controlled one Valve 24 is provided which has a bypass line 21 controls to the pressure valve 16 and with its help when opening the valve a connection between the pump work space 10 and suction chamber 17 is made and when the valve is closed the pump work space 10 is closed. That as a solenoid valve symbolized electrically controlled valve 24 is controlled by a control device 25 according to operating parameters controlled in a manner known per se. With enough large flow cross section of the valve 24 can, however Check valve 16 is also omitted. In this case the Pump work space during the suction stroke only via the electrically controlled Valve filled.

Mit Hilfe dieses elektrisch gesteuerten Ventils, wird der Beginn der Hochdruckförderung des Pumpenkolbens gesteuert. Mit dem Ventil kann letztendlich auch der Spritzbeginn gesteuert werden. Neben dieser Möglichkeit kann der Spritzbegin durch eine separate Spritzbeginnverstelleinrichtung verstellt werden, die bekannterweise einen relativ zum den Nocken abtastenden Pumpenkolben verdrehbarer Nockenantriebsteil aufweist. Beim Verschließen des Ventils baut sich im Pumpenarbeitsraum 10 aufgrund der Förderbewegung des Pumpenkolbens ein für einen Einspritzvorgang erforderlicher Druck auf. Der so auf Einspritzdruck gebrachte Kraftstoff wird über den Längskanal 9 und die Verteilernut 8 einer der Einspritzleitungen 7 zugeführt. Mit dem Wiederöffnen des elektrisch gesteuerten Ventils wird die Hochdruckförderung unterbrochen. Die Schließdauer des Ventils bestimmt die Einspritzmenge, ggf. kann, wie oben gesagt, mit diesem auch der Spritzzeitpunkt gesteuert werden.With the help of this electrically controlled valve, the Controlled start of high-pressure delivery of the pump piston. Ultimately, the valve can also be used to control the start of spraying become. In addition to this possibility, the start of spraying through a separate injection start adjustment device be adjusted, which is known to be relative to the Cam-sensing pump piston rotatable cam drive part having. When closing the valve builds up in Pump work space 10 due to the conveying movement of the pump piston one necessary for an injection process Pressure on. The fuel brought up to injection pressure is one of the longitudinal channel 9 and the distributor groove 8 Injection lines 7 supplied. With the reopening of the the high pressure pumping is electrically controlled valve interrupted. The closing time of the valve determines the injection quantity, if necessary, as mentioned above, this can also be used with this Spray timing can be controlled.

Erfindungsgemäß sind die Hochdruckförderseiten der Nockenflanken der Nocken 5, so ausgebildet, daß sie wie in der Figur 2 oder 3 dargestellt über die Zeit einen Hubverlauf des Pumpenkolbens erzeugen, der unterteilt ist in einen ersten Bereich V der beginnend mit den Förderhub des Kolbens nach einem kleinen Förderhub endet, in einen zweiten Bereich P in dem der Kolben dann gar nicht oder nur so geringfügig in Förderrichtung bewegt wird, daß er in diesem Bereich für eine Hochdruckförderung nicht wirksam ist und eine Einspritzpause entsteht und schließlich in einen dritten Bereich H, in dem die Nockenflanke wieder ansteigt und den Pumpenkolben zwecks weiterer Förderung der Haupteinspritzmenge weiter verschiebt. Im Bereich P kann der Nocken waagerecht, leicht steigend oder auch leicht fallend verlaufen. Die Voreinspritzung wird dabei weiterhin durch das elektrisch gesteuerte Ventil gesteuert und zwar so, daß es geschlossen ist, wenn die Rollen in den zweiten Bereich P kommen.According to the high pressure delivery sides of the cam flanks the cam 5, designed so that it as in the Figure 2 or 3 shown a stroke over time of the pump piston, which is divided into one first area V which begins with the delivery stroke of the piston ends after a small delivery stroke, in a second area P in which the piston then not at all or only so slightly is moved in the conveying direction that he is in this area for high-pressure delivery is not effective and an injection break arises and finally into a third Area H in which the cam flank rises again and the Pump piston for further delivery of the main injection quantity moves further. In area P the cam can be horizontal, slightly rising or falling. The pilot injection is continued by the electric controlled valve controlled so that it is closed is when the roles in the second area P come.

Für einen Betrieb bei niedriger Drehzahl ist dem Diagramm in Figur 2 entnehmbar, daß das elektrisch gesteuerte Ventil, z.B. ein Magnetventil oder auch ein von einem Piezo betätigtes Ventil, zur Steuerung des Beginns der Voreinspritzmengenförderung in U.T., d.h. vor dem Anstieg der Nockenkurve aus einem Grundkreis geschlossen wird und in dem Nockenbereich V vor Erreichen des Nockenbereichs P wieder geöffnet wird. Nach einer Spritzpause im Bereich P folgt dann ein Wiederschließen des Ventils 24 mit Beginn der Hochdruckförderung für die Haupteinspritzung im anschließenden Nockenflankenteil H, wo danach durch Öffnen des Ventils 24 die Hochdruckförderung wiederum unterbrochen und die Haupteinspritzung beendet wird. Im Punkt des Wiedeerschließens sind die Anforderungen an die Exaktheit des Steuerpunktes niedriger als bei einer sonstigen Steuerung eines Spritzbeginns.For operation at low speed, the diagram is in FIG. 2 shows that the electrically controlled valve, e.g. a solenoid valve or one from a piezo actuated valve, for controlling the start of the pre-injection quantity delivery in U.T., i.e. before the rise of Cam curve is closed from a base circle and in which Cam area V again before reaching cam area P. is opened. After a spray break in area P follows then a reclosing of the valve 24 with the start of the high pressure delivery for the main injection in the following Cam flank part H, where thereafter by opening valve 24 the high-pressure delivery is interrupted and the main injection is ended. On the point of reclosing are the requirements for the exactness of the control point lower than with any other control of a Start of spraying.

Für den Betrieb bei hoher Drehzahl ist eine Unterteilung in Vor- und Haupteinsprizung nicht so dringend erforderlich, da hier auf Grund der im wesentlichen zeitkonstant ablaufenden Verbrennungsvorgängen eine Verschiebung der Verbrennung in Drehrichtung nach dem oberen Totpunkt des Brennkraftmaschinenkolbens erfolgt und sich hier Zündverzüge bei eingespritzten Kraaftstoffmengen nicht mehr so nachteilig auf die Geräuschbildung bemerkbar machen. Für diesen Fall, der in Figur 3 gezeigt ist, wird das Ventil 24 so angesteuert, daß es erst im Bereich des Nockenflankenteils P geschlossen wird, so daß es sicher geschlossen ist, wenn die Kraftstoffförderung für die nun alleinige Haupteinspritzung im Bereich des sich dem Bereich P anschließenden Nockenflankenteils H erfolgt. Das Ende der Einspritzung wird wiederum durch Öffnen des Ventils gesteuert, was dann in der Regel noch vor dem oberen Totpunkt des Nocken der Einspritzpumpen erfolgt.There is a subdivision for operation at high speed not so urgently required in pre and main injection, because here due to the essentially constant time ongoing combustion processes a shift in combustion in the direction of rotation after the top dead center of the internal combustion engine piston occurs and ignition delays occur here injected amounts of fuel no longer so disadvantageous to make it noticeable. In this case, 3, the valve 24 becomes like this controlled that it is only in the region of the cam flank part P is closed so that it is securely closed when the Fuel delivery for the now main injection in the area of the cam flank part adjoining area P. H is done. The end of the injection will turn controlled by opening the valve, which then usually even before the top dead center of the cam of the injection pumps he follows.

Diese Ansteuerung hat den Vorteil, daß bei hohen Drehzahlen der Pumpenarbeitsraum der Einspritzpumpe ausreichend mit Kraftstoff gefüllt werden kann, da die Füllphase nun gegen über der Steuerung bei niedriger Drehzahl verlängert ist und die Kolbenbewegung in Füllrichtung, d.h. beim Saughub nur bis in den Hubbereich gelangen muß auf dem sich der zweite Berreich P befindet. Wegen der erst ab dem Bereich P erfolgenden Hochdruckförderung ist die erforderliche Füllmenge des Pumpemnarbeitsraumes reduziert. Das elektrisch gesteuerte Ventil schließt also erst im Bereich P der Nockenflanke, so daß der Saughub zum Angesaugen von Kraftstoff über die ablaufende Nockenflanke V voll ausgenutzt werden kann. Der Einströmfüllungseffekt wirkt sich noch im beginnenden Teil der Nockenflanke vor dem Bereich P aus solange das Ventil noch nicht geschlossen ist.This control has the advantage that at high speeds the pump workspace of the injection pump is sufficient Fuel can be filled because the filling phase is now against is extended above the control at low speed and the piston movement in the filling direction, i.e. during the suction stroke only must reach the stroke range on which the second Area P is located. Because of the only starting from area P. High-pressure delivery is the required filling quantity of the pump working room reduced. The electric The controlled valve therefore closes only in the region P Cam flank so that the suction stroke for sucking fuel fully exploited via the trailing cam flank V. can be. The inflow filling effect still affects the beginning part of the cam flank in front of area P as long the valve is not yet closed.

In Einzelfällen ist es möglich, die Nockenform zu modifizieren, im Sinne einer gewollten unterteilten Einspritzung und in Unterstützung der Steuerarbeit des Ventils. Statt eine rückläufigen Hubbewegung des Kolben zu erzeugen, kann dieser auch lediglich in seiner Stellung verharren oder nur so geringfügig weiterbewegt werden, daß seine Bewegung nicht ausreicht, eine Einspritzung nennenswerter Art zu ermöglichen, derart, daß auch schon ohne dem Einfluß des Ventils eine wirksame Spritzpause konstruktiv vorgegebener Länge auftreten kann, die die Kraftstoffzufuhr in den Brennraum der Brennkraftmaschine reduziert, so daß der Druckanstieg im Brennraum kleiner wird und eine geräuscharme Verbrennung erzielt werden kann.In individual cases it is possible to close the cam shape modify, in the sense of a deliberate divided injection and in support of the control work of the valve. Instead of creating a retrograde stroke of the piston, it can only remain in its position or only be moved so slightly that its movement an injection of any kind is not sufficient enable such that even without the influence of Valve an effective spray break structurally predetermined Length can occur, the fuel supply to the combustion chamber the internal combustion engine is reduced, so that the pressure increase becomes smaller in the combustion chamber and low-noise combustion can be achieved.

Claims (1)

  1. Fuel injection system having a fuel injection pump with a pump piston (1), which is driven by a cam drive provided with at least one cam (5) and bounds a pump working chamber (10), which is used to supply at least one fuel injection valve (13) with fuel injection quantities brought to injection pressure, and also having an electrically controlled valve (24), via which the pump working chamber (10) of the fuel injection pump is connected to a relief chamber (17) or closed in order to control the injection, and having interruption to the injection between a pilot and a main injection per injection operation, the at least one cam (5) being designed such that on that side of its cam flank which moves the pump piston (1) to its delivery stroke, it has a first sub area (V) , in which the pump piston (1) executes a delivery stroke to carry out a pilot injection, has a second sub area (P), in which the pump piston (1), after completing the pilot injection, is moved in the delivery direction and then, in order to carry out the delivery stroke for the main injection, has a third sub area (H), the electrically controlled valve (24) being driven such that, at low rotational speed, it is closed before the start of the first sub area (V) and is opened in the first sub area (V) to terminate the pilot injection and then, in order to carry out the main injection, is closed again at the start of the third sub area and opened again in this third sub area of the cam (5), before reaching the top dead centre of the cam (5), characterized in that in the second sub area (P), the pump piston (1), after terminating the pilot injection, substantially remains in the position it has reached there or is moved only slightly in the delivery direction or the direction opposite to the delivery direction, and in that, at high rotational speed, in order to initiate a main injection without a preceding pilot injection, the electrically controlled valve (24) is closed within the second sub area (P) and opened again within the third sub area (H) to terminate the main injection, before reaching the top dead centre.
EP98912246A 1997-04-25 1998-02-17 Fuel injection system Expired - Lifetime EP0910739B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19717493 1997-04-25
DE19717493A DE19717493A1 (en) 1997-04-25 1997-04-25 Fuel injection system
PCT/DE1998/000452 WO1998049442A1 (en) 1997-04-25 1998-02-17 Fuel injection system

Publications (2)

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EP0910739A1 EP0910739A1 (en) 1999-04-28
EP0910739B1 true EP0910739B1 (en) 2001-10-04

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US (1) US6079388A (en)
EP (1) EP0910739B1 (en)
JP (1) JP2000513783A (en)
CN (1) CN1089854C (en)
CZ (1) CZ291627B6 (en)
DE (2) DE19717493A1 (en)
RU (1) RU2196246C2 (en)
WO (1) WO1998049442A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10101107A1 (en) * 2001-01-12 2002-07-25 Bosch Gmbh Robert Fuel injection system
JP2003343396A (en) * 2002-05-22 2003-12-03 Mitsubishi Electric Corp High pressure fuel supply equipment
FI119120B (en) * 2004-01-23 2008-07-31 Waertsilae Finland Oy Apparatus and Method for Modifying Fuel Injection Pressure
DE102010027745A1 (en) * 2010-04-14 2011-10-20 Robert Bosch Gmbh high pressure pump

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3690768A (en) * 1969-02-28 1972-09-12 Mitsubishi Motors Corp Diesel fuel injection system with improved starting performance
US4838232A (en) * 1984-08-14 1989-06-13 Ail Corporation Fuel delivery control system
JPS62110566U (en) * 1985-12-27 1987-07-14
JPS635140A (en) * 1986-06-24 1988-01-11 Diesel Kiki Co Ltd Injection control method for fuel injection pump
DE3629751C2 (en) * 1986-09-01 1998-07-02 Bosch Gmbh Robert Pre-injection device for internal combustion engines
DE3929747A1 (en) * 1989-09-07 1991-03-14 Bosch Gmbh Robert METHOD AND DEVICE FOR CONTROLLING FUEL INJECTION
US5325837A (en) * 1992-11-19 1994-07-05 Robert Bosch Gmbh Fuel injection apparatus for internal combustion engines
DE69414745T2 (en) * 1993-04-09 1999-07-29 Zexel Corp Fuel injector
GB9509610D0 (en) * 1995-05-12 1995-07-05 Lucas Ind Plc Fuel system

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CN1224484A (en) 1999-07-28
US6079388A (en) 2000-06-27
WO1998049442A1 (en) 1998-11-05
JP2000513783A (en) 2000-10-17
CZ291627B6 (en) 2003-04-16
CN1089854C (en) 2002-08-28
DE19717493A1 (en) 1998-10-29
DE59801622D1 (en) 2001-11-08
RU2196246C2 (en) 2003-01-10
EP0910739A1 (en) 1999-04-28
CZ419598A3 (en) 1999-06-16

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