EP0505522B1 - Fuel injection pump for internal combustion engines - Google Patents

Fuel injection pump for internal combustion engines Download PDF

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Publication number
EP0505522B1
EP0505522B1 EP91915790A EP91915790A EP0505522B1 EP 0505522 B1 EP0505522 B1 EP 0505522B1 EP 91915790 A EP91915790 A EP 91915790A EP 91915790 A EP91915790 A EP 91915790A EP 0505522 B1 EP0505522 B1 EP 0505522B1
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EP
European Patent Office
Prior art keywords
fuel
pump
valve
chamber
space
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Expired - Lifetime
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EP91915790A
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German (de)
French (fr)
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EP0505522A1 (en
Inventor
Wolfgang Braun
Dieter Junger
Helmut Laufer
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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
    • F02M53/00—Fuel-injection apparatus characterised by having heating, cooling or thermally-insulating means
    • 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
    • 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 for internal combustion engines according to the preamble of claim 1.
  • Such a fuel injection pump is known from DE-A-3 500 618.
  • This fuel injection pump has a pump piston which delimits a pump working chamber which can be connected to a suction chamber which is formed by the collecting chamber during a respective suction stroke and during a controlled part of the delivery stroke of the pump piston via a fuel channel consisting of a first and second prechamber and a collecting chamber is.
  • Fuel is conveyed from a fuel reservoir into the collecting chamber.
  • the fuel channel is controlled by an electrically operated valve.
  • the pump work space can be connected via a distributor opening arranged in a distributor during a respective delivery stroke of the pump piston to one of a plurality of pressure channels which are connected to the injection points of the internal combustion engine via injection lines.
  • the fuel delivery under high pressure in the injection lines is determined by the closing phase of the valve.
  • a return line connected to the suction side of the fuel injection pump branches off from the singing chamber and leads away from the collection chamber. Fuel therefore flows continuously through the collecting chamber.
  • the valve for ending the high-pressure delivery is opened, fuel flows from the pump work space back into the collecting chamber via the fuel channel and can return from the collecting chamber via the fuel return to the suction side of the fuel injection pump.
  • the fuel flowing out of the pump work space is heated as a result of the high pressure formation in the pump work space, so that the temperature of the fuel in the collection chamber is increased.
  • the fuel injection pump with the features according to claim 1 has the advantage that when the high-pressure delivery ends with the valve open, fuel flowing out of the pump work chamber can reach the fuel return directly via the bypass line and thus does not lead to a sharp increase in the temperature of the fuel in the suction chamber.
  • the amount of fuel flowing out via the bypass line can be specifically determined by dimensioning the throttle accordingly.
  • FIG. 1 shows a longitudinal section of a fuel injection pump in a schematic representation
  • FIG. 2 shows the detail of the fuel injection pump designated II in FIG. 1 in an enlarged representation.
  • a fuel injection pump of the distributor type shown in FIGS. 1 and 2 has a pump piston 12 which works in a cylinder bore 10 of a cylinder liner 11 and which is driven via a drive shaft 13 by a cam drive consisting of a roller ring 14 and a front cam disk 15 into a reciprocating as well as is also set into a rotating movement at the same time.
  • the fuel injection pump has a housing 17 which delimits an interior space 18 which serves as a suction space and to which fuel is supplied by a feed pump 19 from a storage container.
  • a distributor body 22 is inserted into the housing.
  • the pump piston 12 is provided with a distributor groove 23 in its end region arranged in the cylinder bore 10.
  • the cylinder liner 11 and the distributor body 22 have delivery channels 24 corresponding to the number of cylinders of the internal combustion engine operated by the fuel injection pump, through which fuel can reach the injection valves on the cylinders of the internal combustion engine via a pressure valve 25 and injection lines 26.
  • the distributor body 22 has a stepped bore 28 which extends coaxially to the longitudinal axis 27 of the pump piston 12.
  • the cylinder liner 11 is inserted into the bore 28 in its area with a smaller diameter facing the interior 18.
  • the cylinder liner 11 projects into the interior 18 of the fuel injection pump and is supported with a flange 29 on an annular shoulder 30 formed at the transition of the bore 28 to the smaller diameter from the interior 18.
  • the flange 29 of the cylinder liner 11 is conical in its end region arranged in the region of the bore 28 with the larger diameter, with a cross section tapering towards its end.
  • the cylinder bore 10 has an enlarged diameter in the end region of the cylinder liner 11 arranged in the bore 28.
  • an electrically controlled valve 32 is used from the outside, which closes the bore 28.
  • the valve 32 is designed, for example, as a solenoid valve.
  • the bore 28 is sealed to the outside by two sealing rings 35 inserted at a distance from each other in an annular groove 33 on the outer circumference of the valve housing 34.
  • a valve body 37 is inserted, which projects with its end region out of the valve housing towards the cylinder liner 11 and there clamps a sealing ring 38 between it and the cylinder liner 11.
  • the sealing ring 38 is fitted radially with a small clearance in a shoulder, which is preferably arranged in the cylinder liner 11, and can thereby absorb radial forces which occur as a result of the pressurization, and thus seals a pump work chamber 40 enclosed by the pump piston 12 in the cylinder bore 10 Hole 28 down.
  • This configuration defines an annular space 41 between the end of the cylinder liner 11, the valve body and the valve housing 34.
  • the annular space 41 is connected to the interior 18 of the fuel injection pump via a fuel channel 42 in the distributor body 22.
  • a bypass line 43 leads through the valve housing 34 diametrically opposite the channel 42 and extends approximately parallel to the longitudinal axis 27 of the pump piston, in which a throttle 44 is arranged.
  • the bypass line 43 opens via a short transverse bore 46 into an annular space 48 formed by an annular groove arranged between the sealing rings 35 in the outer circumference of the valve housing 34 and the wall of the bore 28, which in turn is connected to a transverse bore 49 in the distributor body 22.
  • the transverse bore 49 in the distributor body 22 is connected via a return line 51 to the fuel reservoir 20 or the suction line of the feed pump 19.
  • the interior 18 of the fuel injection pump is also connected in a known manner to the fuel return line 51 via a throttle 52.
  • the valve 32 has, as the closing member, a needle 57 which is tightly guided in a blind bore 56 in the valve body 37, the blind bore 56 having an enlarged cross-sectional area which forms a pressure chamber 58.
  • the pressure chamber 58 of the valve 32 is connected to the pump working chamber 40 via a transverse bore 61 and a longitudinal bore 59 in the valve body 37.
  • the needle 57 has a conical sealing surface 62 towards the working chamber 40, which cooperates with a sealing seat 63 of the blind bore 56, which is likewise conical, at the transition from the pressure chamber 58 to the blind bore.
  • the needle 57 has an area 64 with a reduced cross section.
  • the pressure prevailing in the pump work chamber 40 acts in the pressure chamber 58 on both end faces of the area 64 of the needle 57, so that no resulting compressive force acts on it.
  • the pump working chamber 40 is connected via the bore 59, the transverse bore 61, the pressure chamber 58, a further transverse bore 66 in the valve body 37 and an opening 67 in the valve housing 34 to the annular space 41 and via this and the fuel channel 42 to the interior 18 .
  • the opening and closing times and the opening and closing times of the valve 34 are controlled as a function of various operating parameters, such as speed, load, etc.
  • a rotary encoder 68 is provided for detecting the speed and the rotational position of the drive shaft 13.
  • the distributor groove 23 is connected to one of the delivery channels 24 and as soon as the injection valve opens, fuel flows under high pressure to the relevant injection point.
  • the valve 32 is opened and the fuel flows from the pump working space 40 through the valve 32 into the annular space 41. From there, part of the fuel flows back through the fuel channel 42 into the interior 18. Another part of the fuel flows through the throttle 44 into the further annular space 48, flows through this and the transverse bore 49 in the distributor body 22 and returns via the return line 51 to the fuel reservoir 20.
  • fuel flows continuously from the interior 18 via the annular space 41, the throttle 44 and the annular space 48, since there is a higher fuel pressure in the interior 18 than in the return line 51.
  • the fuel flow through the two annular spaces 41 and 48 causes the valve 32 and the cylinder sleeve in the area of the pump work space 40 is washed by the cooler fuel from the interior and thus cooled, and the heated fuel flowing out of the pump work space following the fuel injection phase is returned to the pump work space to a much lesser extent during the suction stroke.
  • the fuel flow flowing through the annular spaces 41 and 48 can be adjusted by appropriate dimensioning and tuning of the throttles 44 and 52 to achieve a desired cooling.

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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)

Abstract

The fuel injection pump has a piston (12) acting in a cylindrical boring (10) of a cylindrical bush (11). In the cylindrical boring (10), a pump working chamber (40) is limited by the piston (12) on one side and an electrically controlled valve (32) on the other. The pump working chamber (40) can be connected on the intake stroke of the piston (12) with an intake chamber (18) via the valve (32) to control the injection piston stroke. The cylindrical bush (11) is partly surrounded by an annular space (41) through which the fuel flows between the pump working chamber (40) and the inner chamber (18). From the annular space (41) branches a by-pass (43) through which the fuel flows into a further annular chamber (48) partly surrounding the valve (32). The annular chamber (48) is relieved towards the fuel tank via a return line. The two annular chambers (41, 48) have fuel flowing continuously through them owing to the pressure prevailing in the inner chamber (18), thus providing cooling for the pump working chamber (40) and the valve (32).

Description

Die Erfindung betrifft eine Kraftstoffeinspritzpumpe für Brennkraftmaschinen nach der Gattung des Anspruchs 1.The invention relates to a fuel injection pump for internal combustion engines according to the preamble of claim 1.

Eine solche Kraftstoffeinspritzpumpe ist durch die DE-A- 3 500 618 bekannt. Diese Kraftstoffeinspritzpumpe weist einen Pumpenkolben auf, der einen Pumpenarbeitsraum begrenzt, der während eines jeweiligen Saughubs und während eines gesteuerten Teils des Förderhubs des Pumpenkolbens über einen aus einer ersten und zweiten Vorkammer sowie einer Sammelkammer bestehenden Kraftstoffkanal mit einem Saugraum verbindbar ist, welcher durch die Sammelkammer gebildet ist. In die Sammelkammer wird Kraftstoff aus einem Kraftstoffvorratsbehälter gefördert. Der Kraftstoffkanal wird von einem elektrisch betätigten Ventil gesteuert. Der Pumpenarbeitsraum ist über eine in einem Verteiler angeordnete Verteileröffnung während eines jeweiligen Förderhubs des Pumpenkolbens mit einem von mehreren Druckkanälen verbindbar, die über Einspritzleitungen mit den Einspritzstellen der Brennkraftmaschine verbunden sind. Die Kraftstofförderung unter Hochdruck in die Einspritzleitungen ist durch die Schließphase des Ventils bestimmt. Vom Sangraum zweigt dabei ein mit der Saugseite der Kraftstoffeinspritzpumpe verbundener Rücklauf ab, der von der Sammelkammer abführt. Die Sammelkammer wird somit ständig von Kraftstoff durchströmt. Beim Öffnen des Ventils zur Beendigung der Hochdruckförderung strömt aus dem Pumpenarbeitsraum über den Kraftstoffkanal Kraftstoff in die Sammelkammer zurück und kann aus der Sammelkammer über den Kraftstoffrücklauf zur Saugseite der Kraftstoffeinspritzpumpe zurückgelangen. Der aus dem Pumpenarbeitsraum abströmende Kraftstoff ist dabei infolge der Hochdruckbildung im Pumpenarbeitsraum erhitzt, so daß die Temperatur des in der Sammelkammer befindlichen Kraftstoffs erhöht wird. Dieser erwärmte Kraftstoff wird beim nachfolgenden Saughub des Pumpenkolbens wieder angesaugt, was wiederum zu erhöhten Temperaturen im Pumpenarbeitsraum führt, wodurch sich höhere Leckverluste und ein niedrigerer Kompressionsenddruck wegen der reduzierten Fülldichte ergeben, was sich negativ auf die konstruktiv vorgegebene Leistung auswirkt. Zwar wird durch die Durchströmung der Sammelkammer eine Abkühlung des Kraftstoffs erreicht, jedoch ist, um die Kraftstofftemperatur niedrig zu halten, unter Umständen eine große Kraftstoffördermenge erforderlich, die ständig in die Sammelkammer gefördert werden muß.Such a fuel injection pump is known from DE-A-3 500 618. This fuel injection pump has a pump piston which delimits a pump working chamber which can be connected to a suction chamber which is formed by the collecting chamber during a respective suction stroke and during a controlled part of the delivery stroke of the pump piston via a fuel channel consisting of a first and second prechamber and a collecting chamber is. Fuel is conveyed from a fuel reservoir into the collecting chamber. The fuel channel is controlled by an electrically operated valve. The pump work space can be connected via a distributor opening arranged in a distributor during a respective delivery stroke of the pump piston to one of a plurality of pressure channels which are connected to the injection points of the internal combustion engine via injection lines. The fuel delivery under high pressure in the injection lines is determined by the closing phase of the valve. A return line connected to the suction side of the fuel injection pump branches off from the singing chamber and leads away from the collection chamber. Fuel therefore flows continuously through the collecting chamber. When the valve for ending the high-pressure delivery is opened, fuel flows from the pump work space back into the collecting chamber via the fuel channel and can return from the collecting chamber via the fuel return to the suction side of the fuel injection pump. The fuel flowing out of the pump work space is heated as a result of the high pressure formation in the pump work space, so that the temperature of the fuel in the collection chamber is increased. This heated fuel is drawn in again during the subsequent suction stroke of the pump piston, which in turn leads to increased temperatures in the pump work space, which results in higher leakage losses and a lower compression end pressure due to the reduced filling density, which has a negative effect on the design performance. A through the flow through the collection chamber Cooling of the fuel is achieved, however, in order to keep the fuel temperature low, a large amount of fuel delivery may be required, which must be continuously fed into the collection chamber.

Die Kraftstoffeinspritzpumpe mit den Merkmalen gemäß dem Anspruch 1 hat demgegenüber den Vorteil, daß bei Beendigung der Hochdruckförderung bei geöffnetem Ventil aus dem Pumpenarbeitsraum abströmender Kraftstoff direkt über die Bypassleitung zum Kraftstoffrücklauf gelangen kann und somit nicht zu einer starken Temperaturerhöhung des Kraftstoffs im Saugraum führt. Die über die Bypassleitung abströmende Kraftstoffmenge ist dabei durch entsprechende Dimensionierung der Drossel gezielt festlegbar.The fuel injection pump with the features according to claim 1 has the advantage that when the high-pressure delivery ends with the valve open, fuel flowing out of the pump work chamber can reach the fuel return directly via the bypass line and thus does not lead to a sharp increase in the temperature of the fuel in the suction chamber. The amount of fuel flowing out via the bypass line can be specifically determined by dimensioning the throttle accordingly.

Im Unteranspruch sind vorteilhafte Ausgestaltungen und Weiterbildungen der Erfindung gekennzeichnet. Durch die Weiterbildung gemäß Anspruch 2 ist eine Kühlung des Pumpenarbeitsraums erreicht, so daß bei der Verdichtung des Kraftstoffs höhere Drücke erzielt werden können und die Temperatur des über das Ventil abströmenden Kraftstoffs reduziert ist.Advantageous refinements and developments of the invention are characterized in the subclaim. Through the development according to claim 2, cooling of the pump work space is achieved, so that higher pressures can be achieved when compressing the fuel and the temperature of the fuel flowing out via the valve is reduced.

Zeichnungdrawing

Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 eine Kraftstoffeinspritzpumpe im Längsschnitt in schematischer Darstellung und Figur 2 den in Figur 1 mit II bezeichneten Ausschnitt der Kraftstoffeinspritzpumpe in vergrößerter Darstellung.An embodiment of the invention is shown in the drawing and explained in more detail in the following description. 1 shows a longitudinal section of a fuel injection pump in a schematic representation and FIG. 2 shows the detail of the fuel injection pump designated II in FIG. 1 in an enlarged representation.

Beschreibung des AusführungsbeispielsDescription of the embodiment

Eine in den Figuren 1 und 2 dargestellte Kraftstoffeinspritzpumpe der Verteilerbauart weist einen in einer Zylinderbohrung 10 einer Zylinderbüchse 11 arbeitenden Pumpenkolben 12 auf, der über eine Antriebswelle 13 von einem aus einem Rollenring 14 und einer Stirnnockenscheibe 15 bestehenden Nockentrieb sowohl in eine hin- und hergehende als auch gleichzeitig in eine rotierende Bewegung versetzt wird. Die Kraftstoffeinspritzpumpe weist ein Gehäuse 17 auf, das einen Innenraum 18 begrenzt, der als Saugraum dient und dem von einer Förderpumpe 19 Kraftstoff aus einem Vorratsbehälter zugeführt wird. An einer Stirnseite des Gehäuses 18 ist ein Verteilerkörper 22 in das Gehäuse eingesetzt. Der Pumpenkolben 12 ist in seinem in der Zylinderbohrung 10 angeordneten Endbereich mit einer Verteilernut 23 versehen. Die Zylinderbüchse 11, sowie der Verteilerkörper 22 weisen entsprechend der Anzahl der Zylinder der mit der Kraftstoffeinspritzpumpe betriebenen Brennkraftmaschine Förderkanäle 24 auf, durch die Kraftstoff über ein Druckventil 25 und Einspritzleitungen 26 zu den Einspritzventilen an den Zylindern der Brennkraftmaschine gelangen kann.A fuel injection pump of the distributor type shown in FIGS. 1 and 2 has a pump piston 12 which works in a cylinder bore 10 of a cylinder liner 11 and which is driven via a drive shaft 13 by a cam drive consisting of a roller ring 14 and a front cam disk 15 into a reciprocating as well as is also set into a rotating movement at the same time. The fuel injection pump has a housing 17 which delimits an interior space 18 which serves as a suction space and to which fuel is supplied by a feed pump 19 from a storage container. At one end of the housing 18, a distributor body 22 is inserted into the housing. The pump piston 12 is provided with a distributor groove 23 in its end region arranged in the cylinder bore 10. The cylinder liner 11 and the distributor body 22 have delivery channels 24 corresponding to the number of cylinders of the internal combustion engine operated by the fuel injection pump, through which fuel can reach the injection valves on the cylinders of the internal combustion engine via a pressure valve 25 and injection lines 26.

Der Verteilerkörper 22 weist eine koaxial zur längsachse 27 des Pumpenkolbens 12 sich erstreckende, gestufte Bohrung 28 auf. In die Bohrung 28 ist in deren zum Innenraum 18 weisenden Bereich mit kleinerem Durchmesser die Zylinderbüchse 11 eingesetzt. Die Zylinderbuchse 11 ragt in den Innenraum 18 der Kraftstoffeinspritzpumpe und stützt sich mit einem Flansch 29 an einer am Übergang der Bohrung 28 zum kleineren Durchmesser gebildeten Ringschulter 30 zum Innenraum 18 hin ab. Der Flansch 29 der Zylinderbüchse 11 ist in seinem im Bereich der Bohrung 28 mit dem größeren Durchmesser angeordneten Endbereich konisch ausgebildet mit sich zu seinem Ende verjüngendem Querschnitt. Die Zylinderbohrung 10 weist im in der Bohrung 28 angeordneten Endbereich der Zylinderbüchse 11 einen vergrößerten Durchmesser auf.The distributor body 22 has a stepped bore 28 which extends coaxially to the longitudinal axis 27 of the pump piston 12. The cylinder liner 11 is inserted into the bore 28 in its area with a smaller diameter facing the interior 18. The cylinder liner 11 projects into the interior 18 of the fuel injection pump and is supported with a flange 29 on an annular shoulder 30 formed at the transition of the bore 28 to the smaller diameter from the interior 18. The flange 29 of the cylinder liner 11 is conical in its end region arranged in the region of the bore 28 with the larger diameter, with a cross section tapering towards its end. The cylinder bore 10 has an enlarged diameter in the end region of the cylinder liner 11 arranged in the bore 28.

Im Bereich des größeren Durchmessers der Bohrung 28 ist von der Außenseite her ein elektrisch gesteuertes Ventil 32 eingesetzt, das die Bohrung 28 verschließt. Das Ventil 32 ist beispielsweise als ein Magnetventil ausgeführt. Die Bohrung 28 ist nach außen hin durch zwei mit Abstand zueinander in je einer Ringnut 33 am Außenumfang des Ventilgehäuses 34 eingelegte Dichtringe 35 abgedichtet. In das Ventilgehäuse 34 ist ein Ventilkörper 37 eingesetzt, der mit seinem Endbereich aus dem Ventilgehäuse heraus zur Zylinderbüchse 11 hin heraus ragt und dort zwischen sich und der Zylinderbüchse 11 einen Dichtring 38 einspannt. Der Dichtring 38 ist radial mit kleinem Spiel in einem Absatz, welcher bevorzugt in der Zylinderbüchse 11 angeordnet ist, eingepaßt und kann dadurch Radialkräfte, welche infolge der Druckbeaufschlagung auftreten, aufnehmen und dichtet somit einen andererseits vom Pumpenkolben 12 in der Zylinderbohrung 10 eingeschlossenen pumpenarbeitsraum 40 zur Bohrung 28 hin ab. Durch diese Gestaltung wird zwischen dem Ende der Zylinderbüchse 11, dem Ventilkörper und dem Ventilgehäuse 34 ein Ringraum 41 begrenzt. Der Ringraum 41 ist über einen Kraftstoffkanal 42 im Verteilerkörper 22 mit dem Innenraum 18 der Kraftstoffeinspritzpumpe verbunden. Vom Ringraum 41 führt durch das Ventilgehäuse 34 eine dem Kanal 42 diametral gegenüberliegende sich etwa parallel zur Längsachse 27 des Pumpenkolbens erstreckende Bypassleitung 43 ab, in der eine Drossel 44 angeordnet ist. Die Bypassleitung 43 mündet über eine kurze Querbohrung 46 in einen durch eine zwischen den Dichtringen 35 angeordnete Ringnut im Außenumfang des Ventilgehäuses 34 und der Wand der Bohrung 28 gebildeten Ringraum 48, der wiederum mit einer Querbohrung 49 im Verteilerkörper 22 in Verbindung steht. Die Querbohrung 49 im Verteilerkörper 22 ist über eine Rücklaufleitung 51 mit dem Kraftstoffvorratsbehälter 20 oder der Saugleitung der Förderpumpe 19 verbunden. Der Innenraum 18 der Kraftstoffeinspritzpumpe ist in bekannter Weise ebenfalls über eine Drossel 52 mit der Kraftstoffrucklaufleitung 51 verbunden.In the area of the larger diameter of the bore 28, an electrically controlled valve 32 is used from the outside, which closes the bore 28. The valve 32 is designed, for example, as a solenoid valve. The bore 28 is sealed to the outside by two sealing rings 35 inserted at a distance from each other in an annular groove 33 on the outer circumference of the valve housing 34. In the valve housing 34, a valve body 37 is inserted, which projects with its end region out of the valve housing towards the cylinder liner 11 and there clamps a sealing ring 38 between it and the cylinder liner 11. The sealing ring 38 is fitted radially with a small clearance in a shoulder, which is preferably arranged in the cylinder liner 11, and can thereby absorb radial forces which occur as a result of the pressurization, and thus seals a pump work chamber 40 enclosed by the pump piston 12 in the cylinder bore 10 Hole 28 down. This configuration defines an annular space 41 between the end of the cylinder liner 11, the valve body and the valve housing 34. The annular space 41 is connected to the interior 18 of the fuel injection pump via a fuel channel 42 in the distributor body 22. From the annular space 41, a bypass line 43 leads through the valve housing 34 diametrically opposite the channel 42 and extends approximately parallel to the longitudinal axis 27 of the pump piston, in which a throttle 44 is arranged. The bypass line 43 opens via a short transverse bore 46 into an annular space 48 formed by an annular groove arranged between the sealing rings 35 in the outer circumference of the valve housing 34 and the wall of the bore 28, which in turn is connected to a transverse bore 49 in the distributor body 22. The transverse bore 49 in the distributor body 22 is connected via a return line 51 to the fuel reservoir 20 or the suction line of the feed pump 19. The interior 18 of the fuel injection pump is also connected in a known manner to the fuel return line 51 via a throttle 52.

Das Ventil 32 weist als Schließglied eine in einer Sackbohrung 56 im Ventilkörper 37 dicht geführte Nadel 57 auf, wobei die Sackbohrung 56 einen im Querschnitt vergrößerten Bereich aufweist, der einen Druckraum 58 bildet. Der Druckraum 58 des Ventils 32 ist über eine Querbohrung 61 sowie eine Längsbohrung 59 im Ventilkörper 37 mit dem Pumpenarbeitsraum 40 verbunden. Die Nadel 57 weist zum Arbeitsraum 40 hin eine konische Dichtfläche 62 auf, die mit einem ebenfalls konisch ausgebildeten Dichtsitz 63 der Sackbohrung 56 am Übergang vom Druckraum 58 zur Sackbohrung zusammenwirkt. Im Druckraum 58 weist die Nadel 57 einen Bereich 64 mit vermindertem Querschnitt auf. Der im Pumpenarbeitsraum 40 herrschende Druck wirkt im Druckraum 58 auf beide Stirnseiten des Bereichs 64 der Nadel 57, so daß auf diese keine resultierende Druckkraft wirkt. Bei abgehobener Nadel 57 ist der Pumpenarbeitsraum 40 über die Bohrung 59, die Querbohrung 61, den Druckraum 58 eine weitere Querbohrung 66 im Ventilkörper 37 sowie eine Öffnung 67 im Ventilgehäuse 34 mit dem Ringraum 41 und über diesen und den Kraftstoffkanal 42 mit dem Innenraum 18 verbunden.The valve 32 has, as the closing member, a needle 57 which is tightly guided in a blind bore 56 in the valve body 37, the blind bore 56 having an enlarged cross-sectional area which forms a pressure chamber 58. The pressure chamber 58 of the valve 32 is connected to the pump working chamber 40 via a transverse bore 61 and a longitudinal bore 59 in the valve body 37. The needle 57 has a conical sealing surface 62 towards the working chamber 40, which cooperates with a sealing seat 63 of the blind bore 56, which is likewise conical, at the transition from the pressure chamber 58 to the blind bore. In the pressure chamber 58, the needle 57 has an area 64 with a reduced cross section. The pressure prevailing in the pump work chamber 40 acts in the pressure chamber 58 on both end faces of the area 64 of the needle 57, so that no resulting compressive force acts on it. When the needle 57 is lifted, the pump working chamber 40 is connected via the bore 59, the transverse bore 61, the pressure chamber 58, a further transverse bore 66 in the valve body 37 and an opening 67 in the valve housing 34 to the annular space 41 and via this and the fuel channel 42 to the interior 18 .

Die Öffnungs- und Schließdauer sowie der Öffnungs- und Schließzeitpunkt des Ventils 34 wird in Abhängigkeit von verschiedenen Betriebsparametern, wie beispielsweise Drehzahl, Last, usw. gesteuert. Zur Erfassung der Drehzahl sowie der Drehlage der Antriebswelle 13 ist ein Drehgeber 68 vorgesehen. Beim Saughub des Pumpenkolbens 12 ist das Ventil 32 geöffnet und der unter Förderdruck der Förderpumpe stehende Kraftstoff strömt aus dem Innenraum 18 durch den Kanal 42, den Ringraum 41, das Ventil 32 und die Längsbohrung 59 in den Pumpenarbeitsraum 40. Zu einem bestimmten Zeitpunkt beim Förderhub des Pumpenkolbens 12 wird das Ventil 32 geschlossen und im Pumpenarbeitsraum 40 wird Hochdruck aufgebaut. In einer bestimmten Drehstellung des Pumpenkolbens 12 ist die Verteilernut 23 mit einem der Förderkanäle 24 verbunden und sobald das Einspritzventil öffnet, strömt Kraftstoff unter Hochdruck zu der betreffenden Einspritzstelle. Zur Beendigung der Hochdruckförderung wird das Ventil 32 geöffnet und der Kraftstoff strömt aus dem Pumpenarbeitsraum 40 durch das Ventil 32 in den Ringraum 41. Von dort strömt ein Teil des Kraftstoffs durch den Kraftstoffkanal 42 in den Innenraum 18 zurück. Ein weiterer Teil des Kraftstoffs strömt durch die Drossel 44 in den weiteren Ringraum 48, durchströmt diesen und die Querbohrung 49 im Verteilerkörper 22 und gelangt über die Rücklaufleitung 51 in den Kraftstoffvorratsbehälter 20 zurück. Außerdem strömt aus dem Innenraum 18 über den Ringraum 41, die Drossel 44 und den Ringraum 48 ständig Kraftstoff, da im Innenraum 18 ein höherer Kraftstoffdruck herrscht als in der Rücklaufleitung 51. Durch den Kraftstoffstrom durch die beiden Ringräume 41 und 48 wird das Ventil 32 und die Zylinderbüchse im Bereich des Pumpenarbeitsraum 40 vom kühleren Kraftstoff aus dem Innenraum umspült und damit gekühlt und der erhitzte aus dem Pumpenarbeitsraum im Anschluß an die Kraftstoffeinspritzphase abströmende Kraftstoff in weit geringerem Maß beim Saughub dem Pumpenarbeitsraum wieder zugeführt. Durch eine entsprechende Dimensionierung und Abstimmung der Drosseln 44 und 52 kann der durch die Ringräume 41 und 48 strömende Kraftstoffstrom zur Erzielung einer gewünschten Kühlung eingestellt werden.The opening and closing times and the opening and closing times of the valve 34 are controlled as a function of various operating parameters, such as speed, load, etc. A rotary encoder 68 is provided for detecting the speed and the rotational position of the drive shaft 13. During the suction stroke of the pump piston 12, the valve 32 is opened and the fuel under the delivery pressure of the delivery pump flows from the interior 18 through the channel 42, the annular space 41, the valve 32 and the longitudinal bore 59 into the pump work space 40. At a certain point in the delivery stroke of the pump piston 12, the valve 32 is closed and high pressure is built up in the pump work chamber 40. In a certain rotational position of the pump piston 12, the distributor groove 23 is connected to one of the delivery channels 24 and as soon as the injection valve opens, fuel flows under high pressure to the relevant injection point. To end the high-pressure delivery, the valve 32 is opened and the fuel flows from the pump working space 40 through the valve 32 into the annular space 41. From there, part of the fuel flows back through the fuel channel 42 into the interior 18. Another part of the fuel flows through the throttle 44 into the further annular space 48, flows through this and the transverse bore 49 in the distributor body 22 and returns via the return line 51 to the fuel reservoir 20. In addition, fuel flows continuously from the interior 18 via the annular space 41, the throttle 44 and the annular space 48, since there is a higher fuel pressure in the interior 18 than in the return line 51. The fuel flow through the two annular spaces 41 and 48 causes the valve 32 and the cylinder sleeve in the area of the pump work space 40 is washed by the cooler fuel from the interior and thus cooled, and the heated fuel flowing out of the pump work space following the fuel injection phase is returned to the pump work space to a much lesser extent during the suction stroke. The fuel flow flowing through the annular spaces 41 and 48 can be adjusted by appropriate dimensioning and tuning of the throttles 44 and 52 to achieve a desired cooling.

Claims (2)

  1. Fuel-injection pump for internal-combustion engines, with a pump piston (12) limiting a pump working space (40) which, during a respective suction stroke and during a controlled part of the feed stroke of the pump piston (12), can be connected, via a fuel duct (42, 41, 67, 66, 61, 59) controlled by an electrically actuated valve (32), to a suction space (18), into which fuel is fed from a storage tank (20), the pump working space (40) being capable, during a respective feed stroke of the pump piston (12), of being connected to one of a plurality of delivery ducts (24) which are connected via injection conduits to the injection points of the internal-combustion engine, the fuel feed under high pressure into the injection conduits being determined by the closing phase of the valve (32), and a fuel return (51) connected to the suction side of the fuel-injection pump branching off from the suction space (18), characterized in that a bypass (43,46,48,49) connected to the fuel return (51) branches off from the fuel duct (41) between the suction space (18) and the valve (32), in that a throttle (44) is provided in the bypass (43,46, 48,49), and in that the part of the fuel duct (42,41) between the suction space (18) and the branch-off of the bypass (43,46,48,49) has a flow constantly passing through it.
  2. Fuel-injection pump according to Claim 1, characterized in that the pump working space (40) is limited on its circumference by a cylinder liner (11) which is arranged in a bore (28) in the housing part (22), in that an annular space (41) connected to the suction space (18) on the one hand and to the valve (32) on the other hand is formed between the bore (28) and the cylinder liner (11), and in that the bypass conduit (43) branches off from the annular space (41) surrounding the cylinder liner (11).
EP91915790A 1990-10-11 1991-09-11 Fuel injection pump for internal combustion engines Expired - Lifetime EP0505522B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4032279A DE4032279A1 (en) 1990-10-11 1990-10-11 Fuel injection pump for IC engine - has suction and delivery stroke controlled by electrically operated valve across fuel duct
DE4032279 1990-10-11
PCT/DE1991/000723 WO1992007182A1 (en) 1990-10-11 1991-09-11 Fuel injection pump for internal combustion engines

Publications (2)

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EP0505522A1 EP0505522A1 (en) 1992-09-30
EP0505522B1 true EP0505522B1 (en) 1996-12-27

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EP91915790A Expired - Lifetime EP0505522B1 (en) 1990-10-11 1991-09-11 Fuel injection pump for internal combustion engines

Country Status (6)

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US (1) US5273017A (en)
EP (1) EP0505522B1 (en)
JP (1) JP3167324B2 (en)
DE (2) DE4032279A1 (en)
ES (1) ES2095952T3 (en)
WO (1) WO1992007182A1 (en)

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Also Published As

Publication number Publication date
DE4032279A1 (en) 1992-04-16
EP0505522A1 (en) 1992-09-30
US5273017A (en) 1993-12-28
JP3167324B2 (en) 2001-05-21
DE59108434D1 (en) 1997-02-06
JPH05502494A (en) 1993-04-28
WO1992007182A1 (en) 1992-04-30
ES2095952T3 (en) 1997-03-01

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