EP0372238B1 - Fuel injection pump for internal-combustion engines - Google Patents

Fuel injection pump for internal-combustion engines Download PDF

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Publication number
EP0372238B1
EP0372238B1 EP89120542A EP89120542A EP0372238B1 EP 0372238 B1 EP0372238 B1 EP 0372238B1 EP 89120542 A EP89120542 A EP 89120542A EP 89120542 A EP89120542 A EP 89120542A EP 0372238 B1 EP0372238 B1 EP 0372238B1
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EP
European Patent Office
Prior art keywords
pump
fuel
piston
space
duct
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Expired - Lifetime
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EP89120542A
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German (de)
French (fr)
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EP0372238A1 (en
Inventor
Jean Leblanc
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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
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/04—Means for damping vibrations or pressure fluctuations in injection pump inlets or outlets
    • 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
    • F02M39/00—Arrangements of fuel-injection apparatus with respect to engines; Pump drives adapted to such arrangements
    • F02M39/005—Arrangements of fuel feed-pumps with respect to fuel injection apparatus
    • 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
    • F02M41/02—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor being spaced from pumping elements
    • F02M41/06—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor being spaced from pumping elements the distributor rotating
    • 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

Definitions

  • the invention relates to a fuel injection pump according to the preamble of the main claim.
  • a fuel injection pump known from DE-OS 33 18 236, the fuel delivered and compressed by a pump cylinder is fed to a store in the amount exceeding the required injection quantity and is intended to push it back into the pump workspace until the start of the suction stroke.
  • the accumulator is under high pressure due to the immediate absorption of the control surge until it is emptied; this requires a massive dimensioning of the memory and causes sealing problems.
  • there are different charge states of the accumulator and inaccuracies in the compressibility of the accumulator volume this does not guarantee that, even at high engine speeds, all of the fuel that has been cut off is returned to the pump work chamber.
  • the connection between the accumulator and the pump work space is controlled via control edges, which are realized by annular and longitudinal grooves embodied in the pump piston. The ring and longitudinal grooves take over part of the fuel flow between the accumulator and the pump work space.
  • FR-A 2 536 464 discloses a fuel injection pump in which the injection quantity is controlled by an electrically controlled valve.
  • the device according to the invention with the characterizing features of the main claim has the advantage that the control of the fuel supply of the pump work space can be represented by a simple device for which the use of a pump piston in its function as a control and distribution element for the fuel flow from and to the Pump work space is no longer required.
  • the device according to the invention is essentially formed by a simple feed pump which works on the displacement principle and an electrically controlled valve which works as a control means.
  • the feed pump is a small pre-feed pump that is able to absorb the exhaust surge up to a limited pressure level, which means that the dimensioning of the parts that are in effect with the pump and the Sealing problem resigns.
  • the economic advantages are further emphasized by the possibility of dispensing with the built-in valve in the device, since the basic device is adaptable to various types of systems which have a directly controlled electric valve.
  • the fuel quantity control An electrically controlled valve enables an exact allocation of the injection quantity, since the degree of backfilling of the pump work space is independent of the dependence of a variable storage return flow.
  • the measures listed in the subclaims permit advantageous developments and improvements of the fuel injection pump specified in the main claim.
  • the displacement element of the feed pump is designed as a stepped piston so that it is possible to supply more fuel to the pump work space during the filling process than was displaced by the pump piston during the previous movement section between the end of the pump and the reversal point in the uppermost position of movement and was driven off to the device , which leads to faster filling of the pump work space and faster operating speeds of the internal combustion engine.
  • FIG. 1 shows a partial longitudinal section through a radial piston pump
  • FIG. 2 shows an exemplary embodiment in a schematic illustration
  • FIG. 3 shows the movement plan of the pump piston.
  • a rotating distributor 2 which is guided in stationary bearings by a plurality of pumps which are radial to the distributor 2
  • Pump piston is supplied under pressure fuel.
  • a pump piston 3 is described in more detail here by way of example.
  • annular groove 4 is provided on the distributor 2. It is connected to a pump work chamber 5, the volume of which is periodically changed by the axially moving pump piston 3.
  • the pump piston 3 is sealingly and displaceably mounted in a bore 6 of a stationary piston carrier 7 that extends radially to the distributor 2.
  • a cranked spring plate 9 engages in an annular groove 8.
  • a piston return spring 10 acts on the bottom of the spring plate 9, the other end of which is supported in an annular groove 11 of the piston carrier 7.
  • a pot-shaped roller tappet 12 Concentrically surrounding the piston return spring 10 and also engaging with its cylindrical jacket in the annular groove 11, a pot-shaped roller tappet 12 with its inner bottom surface forms the contact surface for the side of the base of the spring plate 9 facing away from the piston return spring 10.
  • roller plunger 12 The outer bottom surface of the roller plunger 12 is due to the tension of the piston return spring 10 in frictional engagement with a roller 13, which is supported in a cam ring 14 driven synchronously with the distributor 2, through the inwardly directed cam of which the pump piston 3 is directed against the deflection of the piston return spring , the pump workspace 5 performs a reducing stroke movement.
  • the fuel supply and the derivation of the excess fuel quantity of the pump work chamber 5 which has not been injected takes place via a fuel channel 15 which opens into a memory 16.
  • This has a movable wall 17 which is adjustable against the force of a spring 18 and one in shape from a provided stroke an annular groove designed relief opening 19, which is connected to a suction chamber 20 contained in the fuel injection pump, which is kept at a low pressure by means of a feed pump (not shown).
  • An electrically controlled valve 21 is inserted into the fuel channel 15.
  • the movable wall 17 of the accumulator 16 displaces a part of a stepped piston 22 which is smaller in diameter and which is displaceably mounted in a part of a stepped bore 51 in a sealing manner relative to the accumulator 16.
  • the larger diameter portion of the stepped piston 22 forms in a feed pump 23 a displacement element 24 with a displacement surface 25 formed from the annular surface between the large diameter and the small diameter of the stepped piston 22, which together with the other part of the stepped bore 51 forms a displacement space 26, which acts as a fuel storage space trained, limited.
  • the displacement space 26 has a suction line 27 ending in the suction space 20.
  • a first check valve 28 is inserted into this in such a way that a backflow from the displacement space 26 to the suction space 20 is prevented.
  • a fuel supply channel 29 leads away from the displacement space 26.
  • the delivery lines 32 are distributed according to the number of cylinders to be supplied to the associated internal combustion engine on the circumference of the bore 34 leading the distributor 2 and each contain a relief valve (not shown here) and an injection valve 33 each.
  • Figure 3 shows the elevation curve of the pump piston 3 over the angle of rotation.
  • the valve 21 in the point FB which indicates the start of delivery
  • this begins its high-pressure delivery, which is described in the point FE, which describes the end of delivery
  • the movable wall 17 reaches the relief opening 19, which opens the connection from the pump work chamber 5 to a suction chamber 20 contained in the fuel injection pump, the pressure level of which is comparatively low. This limits the pressure increase in the accumulator 16.
  • the stepped piston 22 is deflected. Whose Displacement surface 25 increases the volume in the displacement space 26, the pressure level of which drops below that in the suction space 20. This pressure difference is compensated for by opening the first check valve 28 and fuel flow from the reservoir 20, which is pressurized by a pre-feed pump at low pressure, through the first check valve 28 into the displacement space 26.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fuel-Injection Apparatus (AREA)

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einer Kraftstoffeinspritzpumpe nach der Gattung des Hauptanspruchs. Bei einer solchen durch die DE-OS 33 18 236 bekannten Kraftstoffeinspritzpumpe wird der von einem Pumpenzylinder geförderte und verdichtete Kraftstoff in dem die benötigte Einspritzmenge übersteigenden Maß einem Speicher zugeführt, der ihn bis zum Beginn des Saughubs wieder in den Pumpenarbeitsraum zurückschieben soll. Der Speicher steht durch die unmittelbare Aufnahme des Absteuerstoßes bis zu seiner Entleerung unter hohem Druck; dies bedingt eine massive Dimensionierung des Speichers und ruft Abdichtprobleme hervor. Je nach der Drehzahl der Brennkraftmaschine ergeben sich unterschiedliche Ladungszustände des Speichers und Ungenauigkeiten in der Kompressibilität des Speichervolumens; damit ist nicht gewährleistet, daß auch bei hohen Drehzahlen der Brennkraftmaschine aller abgesteuerter Kraftstoff wieder in den Pumpenarbeitsraum zurückgesteuert wird. Die Steuerung der Verbindung zwischen Speicher und Pumpenarbeitsraum erfolgt über Steuerkanten, die durch im Pumpenkolben verkörperte Ring- und Längsnuten verwirklicht sind. Die Ring- und Längsnuten übernehmen einen Teil der Kraftstofführung zwischen Speicher und Pumpenarbeitsraum.The invention relates to a fuel injection pump according to the preamble of the main claim. In such a fuel injection pump known from DE-OS 33 18 236, the fuel delivered and compressed by a pump cylinder is fed to a store in the amount exceeding the required injection quantity and is intended to push it back into the pump workspace until the start of the suction stroke. The accumulator is under high pressure due to the immediate absorption of the control surge until it is emptied; this requires a massive dimensioning of the memory and causes sealing problems. Depending on the speed of the internal combustion engine, there are different charge states of the accumulator and inaccuracies in the compressibility of the accumulator volume; this does not guarantee that, even at high engine speeds, all of the fuel that has been cut off is returned to the pump work chamber. The connection between the accumulator and the pump work space is controlled via control edges, which are realized by annular and longitudinal grooves embodied in the pump piston. The ring and longitudinal grooves take over part of the fuel flow between the accumulator and the pump work space.

Sie haben systembedingt den Nachteil, daß das in ihnen enthaltene, nicht steuerbare Kraftstoffvolumen als Totvolumen auftritt.System-related, they have the disadvantage that the uncontrollable fuel volume contained in them occurs as dead volume.

Alle diese Umstände beeinträchtigen, insbesondere bei schnellen Ladungswechseln, die exakte Zumessung der einzuspritzenden Kraftstoffmenge und somit die Leistungssteigerung der Brennkraftmaschine durch Anhebung des Drehzahlniveaus. Des weiteren erfordert die Herstellung der Nuten im Pumpenkolben aufwendige Arbeits- und Kontrollschritte, wobei eine Dejustierung durch Verschleiß mittelbar die Funktionserfüllung der Kraftstoffeinspritzpumpe mindert.All of these circumstances, particularly in the case of rapid charge changes, impair the exact metering of the amount of fuel to be injected and thus the increase in performance of the internal combustion engine by increasing the speed level. Furthermore, the production of the grooves in the pump piston requires complex work and control steps, with a misalignment indirectly reducing the function of the fuel injection pump due to wear.

Des weiteren ist durch die FR-A 2 536 464 eine Kraftstoffeinspritzpumpe bekannt, bei der die Steuerung der Einspritzmenge durch ein elektrisch gesteuertes Ventil erfolgt.Furthermore, FR-A 2 536 464 discloses a fuel injection pump in which the injection quantity is controlled by an electrically controlled valve.

Vorteileadvantages

Die erfindungsgemäße Einrichtung mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, daß die Steuerung der Kraftstoffversorgung des Pumpenarbeitsraums durch eine einfache Vorrichtung dargestellt werden kann, für die die Anwendung eines Pumpenkolbens in seiner Funktion als Steuerungs- und Verteilelement für den Kraftstoffluß von und zu dem Pumpenarbeitsraum nicht mehr erforderlich ist. Die erfindungsgemäße Vorrichtung wird im wesentlichen gebildet durch eine einfache Förderpumpe, die nach dem Verdrängerprinzip arbeitet und einem als Steuermittel arbeitenden elektrisch gesteuerten Ventil. Bei der Förderpumpe handelt es sich um eine kleine Vorförderpumpe, die in der Lage ist, den Absteuerstoß bis zu einer begrenzten Druckhöhe aufzunehmen, wodurch der Dimensionierungsaufwand der mit der Pumpe in Wirkung stehenden Teile sowie die Abdichtproblematik zurücktritt. Diese einfachen Komponenten sind kostengünstig herzustellen. Die wirtschaftlichen Vorteile werden noch unterstrichen durch die Möglichkeit, bei der Vorrichtung auf das eingebaute Ventil zu verzichten, da die Grundvorrichtung adaptabel ist an verschiedenartige Systeme, die über ein direkt gesteuertes elektrisches Ventil verfügen. Die Kraftstoffmengensteuerung durch ein elektrisch gesteuertes Ventil ermöglicht eine exakte Einspritzmengenzuordnung, da der Rückfüllgrad des Pumpenarbeitsraums von der Abhängigkeit eines variablen Speicherrückstroms entbunden ist.The device according to the invention with the characterizing features of the main claim has the advantage that the control of the fuel supply of the pump work space can be represented by a simple device for which the use of a pump piston in its function as a control and distribution element for the fuel flow from and to the Pump work space is no longer required. The device according to the invention is essentially formed by a simple feed pump which works on the displacement principle and an electrically controlled valve which works as a control means. The feed pump is a small pre-feed pump that is able to absorb the exhaust surge up to a limited pressure level, which means that the dimensioning of the parts that are in effect with the pump and the Sealing problem resigns. These simple components are inexpensive to manufacture. The economic advantages are further emphasized by the possibility of dispensing with the built-in valve in the device, since the basic device is adaptable to various types of systems which have a directly controlled electric valve. The fuel quantity control An electrically controlled valve enables an exact allocation of the injection quantity, since the degree of backfilling of the pump work space is independent of the dependence of a variable storage return flow.

Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen und Verbesserungen der im Hauptanspruch angegebenen Kraftstoffeinspritzpumpe möglich. Dabei ist das Verdrängerelement der Förderpumpe als Stufenkolben so ausgebildet, daß es möglich ist, dem Pumpenarbeitsraum während des Füllvorgangs mehr Kraftstoff zuzuführen, als während des vorangegangenen Bewegungsabschnitts zwischen Förderende und dem Umkehrpunkt in der obersten Bewegungslage des Pumpenkolbens von diesem verdrängt und zur Vorrichtung hin abgesteuert wurde, was zu einer rascheren Füllung des Pumpenarbeitsraums führt und schnellere Betriebsdrehzahlen der Brennkraftmaschine ermöglicht.The measures listed in the subclaims permit advantageous developments and improvements of the fuel injection pump specified in the main claim. The displacement element of the feed pump is designed as a stepped piston so that it is possible to supply more fuel to the pump work space during the filling process than was displaced by the pump piston during the previous movement section between the end of the pump and the reversal point in the uppermost position of movement and was driven off to the device , which leads to faster filling of the pump work space and faster operating speeds of the internal combustion engine.

Zeichnungdrawing

Die Erfindung ist in der Zeichnung anhand mehrerer Figuren dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 einen partiellen Längsschnitt durch eine Radialkolbenpume, Figur 2 ein Ausführungsbeispiel in schematischer Darstellung und Figur 3 den Bewegungsplan des Pumpenkolbens.The invention is illustrated in the drawing using several figures and explained in more detail in the following description. FIG. 1 shows a partial longitudinal section through a radial piston pump, FIG. 2 shows an exemplary embodiment in a schematic illustration, and FIG. 3 shows the movement plan of the pump piston.

Beschreibung der AusführungsbeispieleDescription of the embodiments

In einem Gehäuse einer Radialkolbeneinspritzpumpe der Verteilerbauart befindet sich ein rotierender Verteiler 2, dem durch mehrere radial zu dem Verteiler 2 stehenden, in ortsfesten Lagern geführten Pumpenkolben unter Druck gesetzter Kraftstoff zugeliefert wird. Beispielhaft wird hier ein Pumpenkolben 3 näher beschrieben. In der Bewegungsebene des Pumpenkolbens 3 ist auf dem Verteiler 2 eine Ringnut 4 vorgesehen. Sie steht in Verbindung mit einem Pumpenarbeitsraum 5, dessen Volumen durch den axial bewegten Pumpenkolben 3 periodisch verändert wird. Der Pumpenkolben 3 ist dichtend und verschiebbar gelagert in einer radial zum Verteiler 2 verlaufenden Bohrung 6 eines ortsfesten Kolbenträgers 7. In dem dem Pumpenarbeitsraum 5 abgewandten Bereich des Pumpenkolbens 3 greift in eine Ringnut 8 ein gekröpfter Federteller 9 ein. Auf den Boden des Federtellers 9 wirkt eine Kolbenrückholfeder 10, deren anderes Ende sich in einer Ringnut 11 des Kolbenträgers 7 abstützt. Konzentrisch die Kolbenrückfeder 10 umgebend und mit seinem zylindrischen Mantel ebenfalls in die Ringnut 11 eingreifend bildet ein topfförmig ausgebildeter Rollenstößel 12 mit seiner inneren Bodenfläche die Auflagefläche für die der Kolbenrückholfeder 10 abgewandten Seite des Bodens des Federtellers 9.In a housing of a radial piston injection pump of the distributor type, there is a rotating distributor 2, which is guided in stationary bearings by a plurality of pumps which are radial to the distributor 2 Pump piston is supplied under pressure fuel. A pump piston 3 is described in more detail here by way of example. In the plane of movement of the pump piston 3, an annular groove 4 is provided on the distributor 2. It is connected to a pump work chamber 5, the volume of which is periodically changed by the axially moving pump piston 3. The pump piston 3 is sealingly and displaceably mounted in a bore 6 of a stationary piston carrier 7 that extends radially to the distributor 2. In the area of the pump piston 3 facing away from the pump working space 5, a cranked spring plate 9 engages in an annular groove 8. A piston return spring 10 acts on the bottom of the spring plate 9, the other end of which is supported in an annular groove 11 of the piston carrier 7. Concentrically surrounding the piston return spring 10 and also engaging with its cylindrical jacket in the annular groove 11, a pot-shaped roller tappet 12 with its inner bottom surface forms the contact surface for the side of the base of the spring plate 9 facing away from the piston return spring 10.

Die äußere Bodenfläche des Rollenstößels 12 steht durch die Spannung der Kolbenrückholfeder 10 im Kraftschluß mit einer Rolle 13, die sich in einem synchron mit dem Verteiler 2 angetriebenen Nockenring 14 abstützt, durch dessen einwärts gerichtete Nocken der Pumpenkolben 3 eine, entgegen der Auslenkung der Kolbenrückholfeder gerichtete, den Pumpenarbeitsraum 5 verkleinernde Hubbewegung ausführt.The outer bottom surface of the roller plunger 12 is due to the tension of the piston return spring 10 in frictional engagement with a roller 13, which is supported in a cam ring 14 driven synchronously with the distributor 2, through the inwardly directed cam of which the pump piston 3 is directed against the deflection of the piston return spring , the pump workspace 5 performs a reducing stroke movement.

Bei dem in Figur 2 dargestellten Ausführungsbeispiel erfolgt die Kraftstoffversorgung und die Ableitung der nicht zur Einspritzung gelangten überschüssigen Kraftstoffmenge des Pumpenarbeitsraums 5 über einen Kraftstoffkanal 15, der in einen Speicher 16 mündet. Dieser weist eine bewegliche Wand 17 auf, die gegen die Kraft einer Feder 18 verstellbar ist und ab einem vorgesehenen Hub eine in Form einer Ringnut ausgebildete Entlastungsöffnung 19 aufsteuert, die mit einem, in der Kraftstoffeinspritzpumpe enthaltenen Saugraum 20 in Verbindung steht, welcher über eine nicht mehr dargestellte Vorförderpumpe auf niedrigem Druck gehalten wird. In den Kraftstoffkanal 15 ist ein elektrisch gesteuertes Ventil 21 eingesetzt. Die bewegliche Wand 17 des Speichers 16 verlagert bei ihrem Hub einen im Durchmesser kleineren Teil eines Stufenkolbens 22, der gegenüber dem Speicher 16 dichtend in einem Teil einer Stufenbohrung 51 verschiebbar gelagert ist. Der im Durchmesser größere Teil des Stufenkolbens 22 bildet in einer Förderpumpe 23 ein Verdrängungselement 24 mit einer aus der Ringfläche zwischen großem Durchmesser und kleinem Durchmesser des Stufenkolbens 22 gebildeten Verdrängerfläche 25, die zusammen mit dem anderen Teil der Stufenbohrung 51 einen Verdrängungsraum 26, der als Kraftstoffvorratsraum ausgebildet ist, begrenzt. Der Verdrängungsraum 26 weist eine in den Saugraum 20 endende Saugleitung 27 auf. In diese ist ein erstes Rückschlagventil 28 derart eingesetzt, daß ein Rückfluß aus dem Verdrängungsraum 26 zum Saugraum 20 unterbunden wird. Vom Verdrängungsraum 26 führt ein Kraftstoffversorgungskanal 29 ab. Dieser weist ein zweites Rückschlagventil 30 auf, das den Kraftstofffluß vom Verdrängungsraum 26 zur Einmündungsstelle des Kraftstoffversorgungskanals 29 in den Kraftstoffkanal 15 zwischen Speicher 16 und dem Ventil 21 freigibt. Vom Pumpenarbeitsraum 5 führt des weiteren eine an der Mantelfläche des Verteilers 2 verlaufende Verteilernut 31 ab, durch die bei der Drehung des Verteilers 2 nacheinander Förderleitungen 32 mit dem Pumpenarbeitsraum 5 beim Förderhub des Pumpenkolbens 3 verbunden werden. Die Förderleitungen 32, von denen hier nur eine gezeigt ist, sind entsprechend der Zahl der zu versorgenden Zylinder der zugehörigen Brennkraftmaschine am Umfang der den Verteiler 2 führenden Bohrung 34 verteilt angeordnet und enthalten je ein hier nicht dargestelltes Entlastungsventil und je ein Einspritzventil 33.In the exemplary embodiment shown in FIG. 2, the fuel supply and the derivation of the excess fuel quantity of the pump work chamber 5 which has not been injected takes place via a fuel channel 15 which opens into a memory 16. This has a movable wall 17 which is adjustable against the force of a spring 18 and one in shape from a provided stroke an annular groove designed relief opening 19, which is connected to a suction chamber 20 contained in the fuel injection pump, which is kept at a low pressure by means of a feed pump (not shown). An electrically controlled valve 21 is inserted into the fuel channel 15. During its stroke, the movable wall 17 of the accumulator 16 displaces a part of a stepped piston 22 which is smaller in diameter and which is displaceably mounted in a part of a stepped bore 51 in a sealing manner relative to the accumulator 16. The larger diameter portion of the stepped piston 22 forms in a feed pump 23 a displacement element 24 with a displacement surface 25 formed from the annular surface between the large diameter and the small diameter of the stepped piston 22, which together with the other part of the stepped bore 51 forms a displacement space 26, which acts as a fuel storage space trained, limited. The displacement space 26 has a suction line 27 ending in the suction space 20. A first check valve 28 is inserted into this in such a way that a backflow from the displacement space 26 to the suction space 20 is prevented. A fuel supply channel 29 leads away from the displacement space 26. This has a second check valve 30, which releases the fuel flow from the displacement space 26 to the junction of the fuel supply channel 29 into the fuel channel 15 between the accumulator 16 and the valve 21. From the pump work space 5 there is also a distributor groove 31 running on the lateral surface of the distributor 2, through which, when the distributor 2 rotates, delivery lines 32 are connected in succession to the pump work space 5 during the delivery stroke of the pump piston 3. The delivery lines 32, only one of which is shown here, are distributed according to the number of cylinders to be supplied to the associated internal combustion engine on the circumference of the bore 34 leading the distributor 2 and each contain a relief valve (not shown here) and an injection valve 33 each.

Anhand der Figuren 2 und 3 soll nun die Arbeitsweise der in Figur 1 gezeigten Kraftstoffeinspritzpumpe erläutert werden. Figur 3 zeigt dabei die Erhebungskurve des Pumpenkolbens 3 über dem Drehwinkel  . Ausgehend von der untersten Bewegungslage des Pumpenkolbens 3 im Punkt UT beginnt dieser nach einem Vorhub hV und dem Schließen des Kraftstoffkanals 15 durch das Ventil 21 im Punkt FB, der den Förderbeginn kennzeichnet, seine Hochdruckförderung, die im Punkt FE, wodurch das Förderende beschrieben ist, nach einem Hub hN dadurch beendet wird, daß das Ventil 21, das sich nur während der Einspritzzeit vom Punkt FB bis Punkt FE in Schließstellung befindet und damit den Kraftstoffkanal 15 sperrt, öffnet, woduch der unter Hochdruck stehende Pumpenarbeitsraum 5 über den Kraftstoffkanal 15 hin zu niedrigem Druckniveau entlastet wird und daduch der Druck im Pumpenarbeitsraum 5 unter den für die Einspritzung notwendigen Offenhaltungsdruck des Einspritzventils 33 fällt. Vom Punkt FE an wird die vom Pumpenkolben 3 bis zu seiner Bewegungsumkehr im oberen Totpunkt OT geförderte, nicht zur Einspritzung gelangte, unter hohem Druck stehende Kraftstoffmenge durch den Kraftstoffkanal 15 in den Speicher 16 übergeschoben, dessen Füllung schon mit dem Vorhub hV begonnen hat und während der Schließstellung des Ventils 21 unterbrochen wurde. Die Auslenkung der den Speicher 16 begrenzenden beweglichen Wand 17 erfolgt bis zum Kräftegleichgewicht zwischen der auf die bewegliche Wand 17 wirkende Druckkraft und der durch den Hub der beweglichen Wand 17 hervorgerufene Rückstellkraft der Feder 18. Überschreitet die dem Speicher 16 zugeführte Kraftstoffmenge ein gewisses Maß, so erreicht die bewegliche Wand 17 die Entlastungsöffnung 19, die die Verbindung aufsteuert von dem Pumpenarbeitsraum 5 zu einem in der Kraftstoffeinspritzpumpe enthaltenen Saugraum 20, dessen Druckniveau vergleichsweise gering ist. Dadurch wird der Druckanstieg im Speicher 16 begrenzt. Zugleich mit der Hubbewegung der beweglichen Wand 17 wird der Stufenkolben 22 ausgelenkt. Dessen Verdrängerfläche 25 vergrößert dabei das Volumen in dem Verdrängungsraum 26, dessen Druckniveau unter jenes im Saugraum 20 absinkt. Diese Druckdifferenz gleicht sich aus durch Öffnen des ersten Rückschlagventils 28 und Kraftstofffluß vom von einer Vorförderungpumpe unter geringen Druck gesetzten Speicher 20 durch das erste Rückschlagventil 28 in den Verdrängungsraum 26. Mit dem Saughub des Pumpenkolbens 3 zwischen OT und UT und geöffnetem Ventil 21 setzt, unterstützt durch die Rückstellkraft der Feder 18, die Umkehrbewegung der beweglichen Wand 17 ein, wodurch sie das im Speicher 16 enthaltene Kraftstoffvolumen wiederum über den Kraftstoffkanal 15 zum Pumpenarbeitsraum 5 zu dessen Füllung für die nach OT beginnende Verdichtungsphase verschiebt. Zugleich mit der Entleerung des Speichers 16 wird die Kraftstoffüllung des Pumpenarbeitsraums 5 ergänzend durch die Umkehrbewegung des Stufenkolbens 22 bewirkt, wobei dessen Verdrängungsfläche 25 zusätzlichen Kraftstoff gegen das nun geschlossene erste Rückschlagventil 28 über das im Kraftstoffversorgungskanal 29 nun in Flußrichtung liegende geöffnete zweite Rückschlagventil 30 in den Kraftstoffkanal 15 zum Pumpenarbeitsraum 5 überführt, bis dieser komplett gefüllt ist.The mode of operation of the fuel injection pump shown in FIG. 1 will now be explained with reference to FIGS. 2 and 3. Figure 3 shows the elevation curve of the pump piston 3 over the angle of rotation. Starting from the lowest position of movement of the pump piston 3 at the point UT, after a preliminary stroke h V and the closing of the fuel channel 15 by the valve 21 in the point FB, which indicates the start of delivery, this begins its high-pressure delivery, which is described in the point FE, which describes the end of delivery , after a stroke h N is ended in that the valve 21, which is only in the closed position during the injection time from point FB to point FE and thus blocks the fuel channel 15, opens, whereby the high-pressure pump working chamber 5 via the fuel channel 15 is relieved to a low pressure level and the pressure in the pump work chamber 5 therefore falls below the open pressure of the injection valve 33 which is necessary for the injection. From point FE onwards, the high-pressure fuel quantity delivered by pump piston 3 until its reversal of movement at top dead center OT, which has not been injected, is pushed through fuel channel 15 into memory 16, the filling of which has already started with the preliminary stroke h V and was interrupted during the closed position of the valve 21. The deflection of the movable wall 17 delimiting the accumulator 16 takes place up to the equilibrium of forces between the compressive force acting on the movable wall 17 and the restoring force of the spring 18 caused by the stroke of the movable wall 17. If the amount of fuel supplied to the accumulator 16 exceeds a certain amount, so the movable wall 17 reaches the relief opening 19, which opens the connection from the pump work chamber 5 to a suction chamber 20 contained in the fuel injection pump, the pressure level of which is comparatively low. This limits the pressure increase in the accumulator 16. At the same time as the lifting movement of the movable wall 17, the stepped piston 22 is deflected. Whose Displacement surface 25 increases the volume in the displacement space 26, the pressure level of which drops below that in the suction space 20. This pressure difference is compensated for by opening the first check valve 28 and fuel flow from the reservoir 20, which is pressurized by a pre-feed pump at low pressure, through the first check valve 28 into the displacement space 26. With the suction stroke of the pump piston 3 between TDC and TDC and open valve 21, assisted by the restoring force of the spring 18, the reverse movement of the movable wall 17, whereby it in turn shifts the fuel volume contained in the accumulator 16 via the fuel channel 15 to the pump work chamber 5 for filling it for the compression phase beginning after TDC. Simultaneously with the emptying of the accumulator 16, the fuel filling of the pump work chamber 5 is additionally effected by the reversing movement of the stepped piston 22, the displacement surface 25 of which pushes additional fuel against the now closed first check valve 28 via the open second check valve 30 in the fuel supply channel 29, which is now located in the flow direction Fuel channel 15 transferred to the pump work space 5 until it is completely filled.

Mit dieser Ausgestaltung erhält man eine rasche Kraftstoffüllung des Pumpenarbeitsraums 5 mit relativ hohem konstanten Fülldruck, wobei auch bei hohen Betriebsdrehzahlen der Brennkraftmaschine für die Kompressionsphasen des Pumpenkolbens 3 ausreichende Kraftstoffeinspritzmengen verfügbar sind und die Steuerung der Kraftstoffversorgung des Pumpenarbeitsraums 5 über ein adaptables Ventil 21 erfolgt.With this configuration, a rapid fuel filling of the pump work chamber 5 is obtained with a relatively high constant filling pressure, sufficient fuel injection quantities being available for the compression phases of the pump piston 3 even at high operating speeds of the internal combustion engine, and the fuel supply to the pump work chamber 5 being controlled via an adaptable valve 21.

Claims (3)

  1. Fuel injection pump having at least one pump working space (5) enclosed by a pump piston (3) in a part of the casing of the fuel injection pump, which pump working space is connected via a fuel duct (15) to a reservoir (16), the reservoir (16) has a wall (17) movable against the force of a spring (18), having a means of control associated with the fuel duct (15), which means of control is controllable in such a way that, during a delivery stroke of the pump piston (3), the pump working space (5) is connected to the reservoir (16) at the end of high pressure injection, and is shut off from the latter before the delivery stroke of the pump piston (3) which serves the injection process has begun and having a fuel supply duct (29) which, during the filling stroke of the pump piston (3), connects the pump working space (5) to a fuel storage space, characterised in that the means of control is an electrically controlled valve (21) which is located in the fuel duct (15), that the fuel supply duct (29) emerges into the fuel duct (15) between valve (21) and reservoir (16), that the movable wall (17) of the reservoir (16), from a specified stroke, activates a relief opening (19) and at the same time actuates the displacement element (24) of a feed pump (23) in the direction of a suction stroke, the displacement space (26) of the feed pump (23) being the fuel storage space, from which branches off the fuel supply duct (29).
  2. Fuel injection pump according to Claim 1, characterised in that the movable wall (17) is the front face of a smaller diameter section of a stepped piston (22) which can be displaced within a stepped bore (51) and that the displacement element (24) is the larger diameter section of the stepped piston (22), with a displacement surface (25), formed by the annular area between the large and small diameters of the stepped piston (22), which bounds the displacement space (26).
  3. Fuel injection pump according to Claim 2, characterised in that the suction duct (27) of the feed pump (23) is supplied with fuel from a priming pump, via a first non-return valve (28) with a suction space (20) positioned in the fuel injection pump and the displacement space (26) of the feed pump (23) is connected to the fuel supply duct (29) via a second non-return valve (30).
EP89120542A 1988-12-02 1989-11-07 Fuel injection pump for internal-combustion engines Expired - Lifetime EP0372238B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3840652 1988-12-02
DE3840652A DE3840652A1 (en) 1988-12-02 1988-12-02 FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES

Publications (2)

Publication Number Publication Date
EP0372238A1 EP0372238A1 (en) 1990-06-13
EP0372238B1 true EP0372238B1 (en) 1992-09-02

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP89120542A Expired - Lifetime EP0372238B1 (en) 1988-12-02 1989-11-07 Fuel injection pump for internal-combustion engines

Country Status (3)

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EP (1) EP0372238B1 (en)
JP (1) JPH02188665A (en)
DE (2) DE3840652A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATA116889A (en) † 1989-05-17 1997-11-15 Kanzler Walter METHOD FOR THERMAL EXHAUST GAS COMBUSTION
DE4135595A1 (en) * 1991-10-29 1993-05-06 Robert Bosch Gmbh, 7000 Stuttgart, De FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES
DE10115168C1 (en) * 2001-03-27 2002-08-22 Orange Gmbh High-pressure fuel pump, in particular for injection systems of internal combustion engines
DE102005042598B4 (en) * 2005-09-07 2008-10-16 Ab Skf tappet

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB468958A (en) * 1936-01-15 1937-07-15 John Forster Alcock Improvements in fuel injection pumps for internal combustion engines
DE3151889C2 (en) * 1981-12-30 1983-12-22 M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8900 Augsburg Fuel injection system on an internal combustion engine
DE3243348A1 (en) * 1982-11-24 1984-05-24 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION PUMP
US4643155A (en) * 1984-10-05 1987-02-17 Olin Corporation Variable stroke, electronically controlled fuel injection control system
DE3521428A1 (en) * 1985-06-14 1986-12-18 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINES

Also Published As

Publication number Publication date
DE58902204D1 (en) 1992-10-08
EP0372238A1 (en) 1990-06-13
DE3840652A1 (en) 1990-06-07
JPH02188665A (en) 1990-07-24

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