EP0633398B1 - Fuel injection pump for internal combustion engines - Google Patents

Fuel injection pump for internal combustion engines Download PDF

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Publication number
EP0633398B1
EP0633398B1 EP94105647A EP94105647A EP0633398B1 EP 0633398 B1 EP0633398 B1 EP 0633398B1 EP 94105647 A EP94105647 A EP 94105647A EP 94105647 A EP94105647 A EP 94105647A EP 0633398 B1 EP0633398 B1 EP 0633398B1
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EP
European Patent Office
Prior art keywords
space
pump
fuel injection
injection pump
fuel
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EP94105647A
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German (de)
French (fr)
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EP0633398A1 (en
Inventor
Wolfgang Ing. Fehlmann
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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
    • 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
    • F02M41/14—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 rotary distributor supporting pump pistons
    • F02M41/1405—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 rotary distributor supporting pump pistons pistons being disposed radially with respect to rotation axis

Definitions

  • the invention relates to a fuel injection pump according to the preamble of claim 1.
  • Such a fuel injection pump has become known, for example, from DE-OS 39 28 612.
  • the fuel accumulator is designed as a diaphragm accumulator and represents a component flanged to the side of the injection pump housing. This component increases the installation dimensions of the injection pump and has a disruptive effect if the fuel accumulator is large.
  • a small fuel reservoir has the disadvantage that the pressure in the intake space drops too much during the intake stroke, which in turn interferes with the function. Apart from this, flanging the fuel reservoir results in additional sealing surfaces to the outside, which in turn increases the risk of fuel leakage on the surface of the injection pump.
  • the known pump has a pump piston which also serves as a distributor and which is driven back and forth by the cam drive and at the same time rotates.
  • the Pump and distributor piston with its end protruding into the suction chamber held by a spring together with a cam disc in contact with a roller ring, whereby the volume of the cam chamber changes periodically due to the movement of the pump piston, combined with periodic brief pressure changes that are used during the suction stroke are to improve the filling process of the pump work space by deflecting the movable wall designed as a membrane under the pressure pulses on the cam space side.
  • the pressures in the suction chamber and in the cam chamber should be approximately the same.
  • the fuel injection pump according to the invention with the features of the characterizing part of claim 1 has the advantage that a return of the pump piston or pistons by means of springs can be dispensed with, in addition the suction space can be kept relatively small, since the shock-like loading of the suction space by the provided by the movable wall at the end of the injection-effective delivery stroke into the suction chamber, the fuel previously brought to the injection pressure is reduced insofar as the movable wall yields to the pressure surge against the lower-pressure engine compartment and absorbs the outflow quantity.
  • the filling process is positively supported by the simultaneous volume change in the suction and engine room.
  • the invention thus enables the fuel accumulator to be larger than known externally arranged accumulators without having to accept unfavorable external dimensions of the fuel injection pump.
  • existing components are used as a fuel accumulator and since the fuel accumulator according to the invention does not have to be flanged to the outside of the fuel injection pump, additional sealing points, which can become leaky, are eliminated.
  • the cavity used as a fuel reservoir is limited by a housing that at least partially surrounds the pump cylinder or cylinders.
  • the plungers that actuate the pump piston or the pump pistons are usually held against the cam by springs.
  • spring elements can be dispensed with, the system of the tappets being secured hydraulically to the cam.
  • the pressure in the suction chamber must therefore also be kept high during the intake stroke and this is made possible by the large-scale fuel accumulator created by the invention.
  • the wall separating the engine compartment from the component comprising the pump cylinder or pumps, or a part thereof is preferably formed by a deformable membrane.
  • the connection of the engine room to the component or the pump cylinder has anyway a seal and this seal can also be used to fix the membrane.
  • the arrangement can, however, also be made according to the invention in such a way that the wall separating the engine compartment from the component having the pump cylinder (s) or part thereof is formed by a displaceable piston which is tightly guided in the component (s) and / or in the engine compartment is. Since such a piston lies within the pump housing, there is no fear of fuel leakage from the housing of the injection pump in this case either.
  • FIG. 1 shows an arrangement in which the pressure-sensitive element separating the engine compartment from the component comprising the pump cylinder (s) is formed by a membrane, in axial cross section.
  • Figures 2 and 3 show two modified embodiments, in axial section, only one half being shown.
  • a fuel injection pump is shown schematically with a housing 1 and an engine room 2.
  • a cylinder liner 3 is used, in which a distributor 4, which is driven in rotation by a drive shaft 5, is guided.
  • Pump pistons 6 are guided in pump cylinders 4 radially introduced into the distributor, between which a pump working space 9 is enclosed. This is connected via an axial channel 10 in the distributor 4 and via a branch bore 42 branching therefrom, the outlet of which from the distributor serves as a distributor opening, during the rotation of the distributor one after the other during pumping movements of the pump pistons 6 with one of a plurality of injection lines 14, which in the Housing 1 of the fuel injection pump run and lead to the individual injection points of the associated internal combustion engine.
  • the pump pistons 6 are driven to their pumping movement via roller tappets 15 with rollers 16, which run on a radially inwardly directed cam track 17 of a cam ring during the rotation of the distributor.
  • the cam ring is essentially stationary and can be adjusted for the start of injection adjustment by means of a pin 19 which is engaged by an injection adjustment piston.
  • the axial channel 10 opens at the end of the distributor into a fuel chamber, which is connected via a line 11 to a suction chamber 12 in the housing of the fuel injection pump.
  • the opening of the axial channel 10 in this space is controlled by a solenoid valve 13, such that when the solenoid valve is open, the pump piston 6 of the pump working chamber 12 can be supplied with fuel during the suction stroke.
  • the solenoid valve is closed and thus determines the start of injection and also the duration over which fuel is delivered under high pressure during the delivery stroke of the pump piston.
  • the start of injection and the injection quantity are varied using a single solenoid valve.
  • a pre-pump 20 sucks fuel from a fuel reservoir 22 via a line 21 and conveys it via lines 23 and 24 into the suction chamber 12.
  • a branch line 25 branches off from the line 23, via which fuel into an engine room 2 the fuel injection pump is promoted. This engine room 2 is relieved to the fuel tank via a pressure control valve 29, which controls the pressure in the engine room.
  • a decoupling throttle 26 is inserted in line 25 in order to ensure that a pressure in engine room 2 can be set with pressure-maintaining valve 29 that is lower than that in suction chamber 12.
  • the suction chamber 12 is separated from the engine room 2 by a movable wall, which is formed here by a membrane 27.
  • the suction chamber is annular and is delimited on the circumferential side by the cylinder liner 3 and the cylindrical housing wall 28 and axially by the membrane 27 on the one hand and the pump housing on the other.
  • the membrane 27 is annular and lies close to the cylindrical housing wall 28 on one side and on the cylindrical peripheral wall of the cylinder liner 3 projecting into the suction space 12 on the other side.
  • the cylindrical housing wall 28 and the circumferential wall of the cylinder liner 3 form an annular space which is coaxial with the axis of the distributor piston 4, at least in the area of the membrane 27.
  • This configuration makes it possible to dispense with the fact that the pistons are supported by springs via the roller tappets 15 with rollers 16 during their suction stroke are held on the cam track 17.
  • the solenoid valve 13 is opened and the fuel, which is kept at a higher pressure, passes from the suction chamber 12 into the pump work chamber 9.
  • the lower engine chamber pressure acts, so that the pistons are moved outwards by the pressure difference until they come into contact with the roller tappets on the cam track.
  • the membrane 27 can be elastic to the engine room 2 evade and thus facilitate the rapid pressure reduction in the pump work space 9.
  • the engine room 2 can also be filled with lubricant, for example engine oil.
  • lubricant for example engine oil.
  • the line 25 and the throttle 26 are omitted and a separate device for the supply of engine oil, for example from the internal combustion engine, must be provided in the engine compartment 2 under appropriate pressure.
  • a support body 29 is provided which is connected to the cylinder liner 3 and the cylindrical one Housing wall 28 is tightly connected.
  • the support body 29 has circumferential grooves 30, in which a sealing ring 31 is inserted.
  • the support body On its end facing the suction chamber 12, the support body has an outer annular groove 32 and an inner annular groove 33, in which sealing rings 34 and 35 are inserted.
  • the support body is supported under the action of the differential pressure acting on the membrane 36 against a stop 44 on the cylindrical outer wall of the cylinder liner 3.
  • the movable wall which separates the suction chamber 12 from the engine room 2 is formed by a piston 37.
  • This has on its outer and inner circumference annular grooves 38 and 39, in which sealing rings 40 and 41 are arranged.
  • the piston 37 which is axially displaceable, is guided close to the cylindrical wall 28 and to the cylinder liner 3.
  • the piston is initially held by the greater pressure in the suction chamber 12 against a stop 45 which limits its path to the engine room.
  • the stop can be provided on the cylindrical housing wall, for example as a snap ring, or on the cylindrical outer wall of the cylinder liner 3.
  • the piston can move back and forth axially slightly when pressure changes occur in the adjacent rooms 2 and 12 due to the actuation and filling processes of the pump work space.

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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 bezieht sich auf eine Kraftstoffeinspritzpumpe gemäß der Gattung des Patentanspruches 1.The invention relates to a fuel injection pump according to the preamble of claim 1.

Eine solche Kraftstoffeinspritzpumpe ist beispielsweise aus der DE-OS 39 28 612 bekanntgeworden. Bei dieser bekannten Ausbildung ist der Kraftstoffspeicher als Membranspeicher ausgebildet und stellt einen seitlich an das Einspritzpumpengehäuse angeflanschten Bauteil dar. Dieser Bauteil vergrößert die Einbaumaße der Einspritzpumpe und wirkt störend, sofern der Kraftstoffspeicher groß ausgebildet wird. Ein kleiner Kraftstoffspeicher bringt aber wieder den Nachteil mit sich, daß beim Ansaugtakt der Druck im Ansaugraum zu stark absinkt, wodurch wieder die Funktion gestört wird. Abgesehen davon ergeben sich durch das Anflanschen des Kraftstoffspeichers zusätzliche Dichtflächen nach außen, was wieder die Gefahr eines Kraftstoffaustrittes an der Oberfläche der Einspritzpumpe vergrößert.Such a fuel injection pump has become known, for example, from DE-OS 39 28 612. In this known design, the fuel accumulator is designed as a diaphragm accumulator and represents a component flanged to the side of the injection pump housing. This component increases the installation dimensions of the injection pump and has a disruptive effect if the fuel accumulator is large. However, a small fuel reservoir has the disadvantage that the pressure in the intake space drops too much during the intake stroke, which in turn interferes with the function. Apart from this, flanging the fuel reservoir results in additional sealing surfaces to the outside, which in turn increases the risk of fuel leakage on the surface of the injection pump.

Weiterhin weist die bekannte Pumpe einen zugleich als Verteiler dienenden Pumpenkolben auf, der durch den Nockenantrieb hin- und hergehend und zugleich rotierend angetrieben wird. Dabei wird der Pumpen- und Verteilerkolben mit seinem in den Saugraum ragenden Ende durch eine Feder zusammen mit einer Nockenscheibe in Anlage an einen Rollenring gehalten, wobei durch die Bewegung des Pumpenkolbens periodisch sich das Volumen des Nockenraumes ändert, verbunden mit periodischen kurzzeitigen Druckänderungen, die beim Saughub dazu benutzt werden, den Füllvorgang des Pumpenarbeitsraumes zu verbessern, indem die als Membran ausgebildete bewegliche Wand unter den nockenraumseitigen Druckpulsen ausgelenkt wird. Die Drücke im Saugraum und im Nockenraum sollen zu diesem Zweck etwa gleich groß sein.Furthermore, the known pump has a pump piston which also serves as a distributor and which is driven back and forth by the cam drive and at the same time rotates. The Pump and distributor piston with its end protruding into the suction chamber held by a spring together with a cam disc in contact with a roller ring, whereby the volume of the cam chamber changes periodically due to the movement of the pump piston, combined with periodic brief pressure changes that are used during the suction stroke are to improve the filling process of the pump work space by deflecting the movable wall designed as a membrane under the pressure pulses on the cam space side. For this purpose, the pressures in the suction chamber and in the cam chamber should be approximately the same.

Die erfindungsgemäße Kraftstoffeinspritzpumpe mit den Merkmalen des Kennzeichens des Anspruchs 1 hat den Vorteil, daß eine Rückführung des oder der Pumpenkolben mittels Federn entfallen kann, wobei zusätzlich der Saugraum verhältnismäßig klein gehalten werden kann, da durch Vorsehung der beweglichen Wand die stoßartige Belastung des Saugraumes durch den zum Ende des einspritzwirksamen Förderhubes in den Saugraum abgegebenen zuvor auf Einspritzdruck gebrachten Kraftstoff insofern verringert wird als die bewegliche Wand dem Druckstoß gegen den unter niedrigerem Druck stehenden Triebwerksraum nachgibt und die Abströmmenge auffängt. Beim Füllhub des Pumpenkolbens wird durch die gleichzeitige Volumenänderung im Saug- und Triebwerksraum der Füllvorgang positiv unterstützt.The fuel injection pump according to the invention with the features of the characterizing part of claim 1 has the advantage that a return of the pump piston or pistons by means of springs can be dispensed with, in addition the suction space can be kept relatively small, since the shock-like loading of the suction space by the provided by the movable wall at the end of the injection-effective delivery stroke into the suction chamber, the fuel previously brought to the injection pressure is reduced insofar as the movable wall yields to the pressure surge against the lower-pressure engine compartment and absorbs the outflow quantity. During the filling stroke of the pump piston, the filling process is positively supported by the simultaneous volume change in the suction and engine room.

Die Erfindung ermöglicht somit den Kraftstoffspeicher größer als bekannte außen angeordnete Speicher auszubilden, ohne ungünstige Außenabmessungen der Kraftstoffeinspritzpumpe in Kauf nehmen zu müssen. Es werden ohnedies bestehende Bauteile als Kraftstoffspeicher ausgenützt und da der erfindungsgemäße Kraftstoffspeicher nicht außen an die Kraftstoffeinspritzpumpe angeflanscht werden muß, entfallen zusätzliche Dichtstellen, welche undicht werden können. Gemäß einer vorteilhaften Ausführungsform der Erfindung ist der als Kraftstoffspeicher ausgenützte Hohlraum von einem den oder die Pumpenzylinder zumindest teilweise umgebenden Gehäuse begrenzt.The invention thus enables the fuel accumulator to be larger than known externally arranged accumulators without having to accept unfavorable external dimensions of the fuel injection pump. In any case, existing components are used as a fuel accumulator and since the fuel accumulator according to the invention does not have to be flanged to the outside of the fuel injection pump, additional sealing points, which can become leaky, are eliminated. According to an advantageous embodiment of the According to the invention, the cavity used as a fuel reservoir is limited by a housing that at least partially surrounds the pump cylinder or cylinders.

Im Triebwerksraum der Kraftstoffeinspritzpumpe werden üblicherweise die den Pumpenkolben oder die Pumpenkolben betätigenden Stößel durch Federn in Anlage am Nocken gehalten. Bei Radialkolbenpumpen kann man auf solche Federelemente verzichten, wobei die Anlage der Stößel am Nocken hydraulisch gesichert wird. Hierfür ist es aber notwendig, den Druck im Triebwerksraum deutlich unter den Druck im Saugraum des Pumpenkolbens abzusenken. Es muß daher der Druck im Saugraum auch beim Ansaugtakt hoch gehalten werden und dies ist durch den durch die Erfindung geschaffenen großräumigen Kraftstoffspeicher ermöglicht.In the engine compartment of the fuel injection pump, the plungers that actuate the pump piston or the pump pistons are usually held against the cam by springs. In the case of radial piston pumps, such spring elements can be dispensed with, the system of the tappets being secured hydraulically to the cam. For this, however, it is necessary to lower the pressure in the engine room significantly below the pressure in the suction chamber of the pump piston. The pressure in the suction chamber must therefore also be kept high during the intake stroke and this is made possible by the large-scale fuel accumulator created by the invention.

Gemäß der Erfindung ist vorzugsweise die den Triebwerksraum von dem den oder die Pumpenzylinder aufweisenden Bauteil trennende Wandung oder ein Teil derselben von einer verformbaren Membrane gebildet. Die Verbindung des Triebwerkraumes mit dem den oder die Pumpenzylinder aufweisenden Bauteil erfordert ohnedies eine Dichtung und diese Dichtung kann gleichzeitig auch zur Festlegung der Membrane ausgenützt werden.According to the invention, the wall separating the engine compartment from the component comprising the pump cylinder or pumps, or a part thereof, is preferably formed by a deformable membrane. The connection of the engine room to the component or the pump cylinder has anyway a seal and this seal can also be used to fix the membrane.

Die Anordnung kann aber gemäß der Erfindung auch so getroffen werden, daß die den Triebwerksraum von dem den oder die Pumpenzylinder aufweisenden Bauteil trennende Wandung oder ein Teil derselben von einem in dem den oder die Pumpenzylinder aufweisenden Bauteil und/oder im Triebwerksraum dicht geführten verschiebbaren Kolben gebildet ist. Da ein solcher Kolben innerhalb des Pumpengehäuses liegt, ist auch in diesem Fall ein Austritt von Kraftstoff aus dem Gehäuse der Einspritzpumpe nicht zu befürchten.The arrangement can, however, also be made according to the invention in such a way that the wall separating the engine compartment from the component having the pump cylinder (s) or part thereof is formed by a displaceable piston which is tightly guided in the component (s) and / or in the engine compartment is. Since such a piston lies within the pump housing, there is no fear of fuel leakage from the housing of the injection pump in this case either.

In der Zeichnung ist die Erfindung anhand von schematischen Ausführungsbeispielen erläutert.In the drawing, the invention is explained using schematic exemplary embodiments.

Figur 1 zeigt eine Anordnung, bei welcher das den Triebwerksraum von dem den oder die Pumpenzylinder aufweisenden Bauteil trennende druckempfindliche Organ von einer Membrane gebildet ist, im Axialquerschnitt. Figuren 2 und 3 zeigen zwei abgewandelte Ausführungsformen, im Axialschnitt, wobei nur eine Hälfte dargestellt ist.FIG. 1 shows an arrangement in which the pressure-sensitive element separating the engine compartment from the component comprising the pump cylinder (s) is formed by a membrane, in axial cross section. Figures 2 and 3 show two modified embodiments, in axial section, only one half being shown.

In Figur 1 ist schematisch eine Kraftstoffeinspritzpumpe dargestellt mit einem Gehäuse 1 und einem Triebwerksraum 2. Im Gehäuse 1 ist eine Zylinderbüchse 3 eingesetzt, in welcher ein Verteiler 4, der durch eine Antriebswelle 5 rotierend angetrieben wird, geführt ist. In radial in den Verteiler eingebrachte Pumpenzylinder 4 sind Pumpenkolben 6 geführt, zwischen denen ein Pumpenarbeitsraum 9 eingeschlossen wird. Dieser ist über einen axialen Kanal 10 im Verteiler 4 und über eine von dieser abzweigenden Querbohrung 42, deren Austritt aus dem Verteiler als Verteileröffnung dient, im Laufe der Drehung des Verteilers nacheinander während Pumpbewegungen der Pumpenkolben 6 mit einer von mehreren Einspritzleitungen 14 verbindbar, die im Gehäuse 1 der Kraftstoffeinspritzpumpe verlaufen und zu den einzelnen Einspritzstellen der zugehörigen Brennkraftmaschine führen. Die Pumpenkolben 6 werden über Rollenstößel 15 mit Rollen 16, die auf einer radial einwärts gerichteten Nockenbahn 17 eines Nockenringes während der Drehung des Verteilers ablaufen, zu ihrer Pumpbewegung angetrieben. Der Nockenring ist im wesentlichen feststehend und kann zur Spritzbeginnverstellung über einen Zapfen 19, an dem ein Spritzverstellkolben angreift, verstellt werden.In Figure 1, a fuel injection pump is shown schematically with a housing 1 and an engine room 2. In the housing 1, a cylinder liner 3 is used, in which a distributor 4, which is driven in rotation by a drive shaft 5, is guided. Pump pistons 6 are guided in pump cylinders 4 radially introduced into the distributor, between which a pump working space 9 is enclosed. This is connected via an axial channel 10 in the distributor 4 and via a branch bore 42 branching therefrom, the outlet of which from the distributor serves as a distributor opening, during the rotation of the distributor one after the other during pumping movements of the pump pistons 6 with one of a plurality of injection lines 14, which in the Housing 1 of the fuel injection pump run and lead to the individual injection points of the associated internal combustion engine. The pump pistons 6 are driven to their pumping movement via roller tappets 15 with rollers 16, which run on a radially inwardly directed cam track 17 of a cam ring during the rotation of the distributor. The cam ring is essentially stationary and can be adjusted for the start of injection adjustment by means of a pin 19 which is engaged by an injection adjustment piston.

Der axiale Kanal 10 mündet stirnseitig des Verteilers in einen Kraftstoffraum, der über eine Leitung 11 mit einem Saugraum 12 im Gehäuse der Kraftstoffeinspritzpumpe verbunden ist. Die Einmündung des axialen Kanals 10 in diesen Raum wird durch ein Magnetventil 13 gesteuert, derart, daß bei geöffnetem Magnetventil während des Saughubs der Pumpenkolben 6 der Pumpenarbeitsraum 12 mit Kraftstoff versorgt werden kann. Zu Beginn der wirksamen Förderung von Kraftstoff unter Hochdruck in eine der Einspritzleitungen 14 wird das Magnetventil geschlossen und bestimmt somit den Einspritzbeginn und auch die Dauer, über die während des Förderhubs des Pumpenkolbens Kraftstoff unter Hochdruck gefördert wird. Somit werden Einspritzbeginn und Einspritzmenge mit Hilfe eines einzigen Magnetventils variiert.The axial channel 10 opens at the end of the distributor into a fuel chamber, which is connected via a line 11 to a suction chamber 12 in the housing of the fuel injection pump. The opening of the axial channel 10 in this space is controlled by a solenoid valve 13, such that when the solenoid valve is open, the pump piston 6 of the pump working chamber 12 can be supplied with fuel during the suction stroke. At the beginning of the effective delivery of fuel under high pressure into one of the injection lines 14, the solenoid valve is closed and thus determines the start of injection and also the duration over which fuel is delivered under high pressure during the delivery stroke of the pump piston. Thus, the start of injection and the injection quantity are varied using a single solenoid valve.

Zur Versorgung des Saugraumes mit Kraftstoff saugt eine Vorpume 20 über eine Leitung 21 Kraftstoff aus einem Kraftstoffvorratsbehälter 22 an und fördert diesen über Leitungen 23 und 24 in den Saugraum 12. Von der Leitung 23 zweigt eine Zweigleitung 25 ab, über die Kraftstoff in einen Triebwerksraum 2 der Kraftstoffeinspritzpumpe gefördert wird. Dieser Triebwerksraum 2 wird über ein Druckhalteventil 29, das den Druck im Triebwerksraum steuert, zum Kraftstoffvorratsbehälter hin entlastet. In der Leitung 25 ist eine Abkoppeldrossel 26 eingesetzt, um zu gewährleisten, daß ein Druck im Triebwerksraum 2 mit dem Druckhalteventil 29 eingestellt werden kann, der kleiner ist, als der im Saugraum 12.In order to supply the suction chamber with fuel, a pre-pump 20 sucks fuel from a fuel reservoir 22 via a line 21 and conveys it via lines 23 and 24 into the suction chamber 12. A branch line 25 branches off from the line 23, via which fuel into an engine room 2 the fuel injection pump is promoted. This engine room 2 is relieved to the fuel tank via a pressure control valve 29, which controls the pressure in the engine room. A decoupling throttle 26 is inserted in line 25 in order to ensure that a pressure in engine room 2 can be set with pressure-maintaining valve 29 that is lower than that in suction chamber 12.

Der Saugraum 12 wird vom Triebwerksraum 2 durch eine bewegliche Wand getrennt, die hier von einer Membran 27 gebildet wird. Der Saugraum ist ringförmig und wird umfangsseitig von der Zylinderbüchse 3 und die zylindrische Gehäusewand 28 sowie axial von der Membran 27 einerseits und dem Pumpengehäuse andererseits begrenzt. Die Membran 27 ist ringförmig und liegt dicht an der zylindrischen Gehäusewand 28 auf ihrer einen Seite und an der zylindrischen Umfangswand der in den Saugraum 12 ragenden Zylinderbüchse 3 auf der anderen Seite an. Die zylindrische Gehäusewand 28 und die Umfangswand der Zylinderbüchse 3 bilden einen zur Achse des Verteilerkolbens 4 koaxialen Ringraum, zumindest im Bereich der Membran 27. Durch diese Ausgestaltung kann darauf verzichtet werden, daß die Kolben während ihres Saughubes durch Federn über die Rollenstößel 15 mit Rollen 16 an der Nockenbahn 17 gehalten werden. Beim Füllhub der Pumpenkolben 6 ist das Magnetventil 13 geöffnet und es gelangt der auf höheren Druck gehaltene Kraftstoff aus dem Saugraum 12 in den Pumpenarbeitsraum 9. Auf der anderen, in den Triebwerksraum 2 ragenden Stirnseite der Pumpenkolben mit gleicher Fläche wirkt der geringere Triebwerksraumdruck, so daß die Kolben durch den Druckunterschied nach außen verschoben werden, bis zur Anlage über die Rollenstößel an der Nockenbahn.The suction chamber 12 is separated from the engine room 2 by a movable wall, which is formed here by a membrane 27. The suction chamber is annular and is delimited on the circumferential side by the cylinder liner 3 and the cylindrical housing wall 28 and axially by the membrane 27 on the one hand and the pump housing on the other. The membrane 27 is annular and lies close to the cylindrical housing wall 28 on one side and on the cylindrical peripheral wall of the cylinder liner 3 projecting into the suction space 12 on the other side. The cylindrical housing wall 28 and the circumferential wall of the cylinder liner 3 form an annular space which is coaxial with the axis of the distributor piston 4, at least in the area of the membrane 27. This configuration makes it possible to dispense with the fact that the pistons are supported by springs via the roller tappets 15 with rollers 16 during their suction stroke are held on the cam track 17. During the filling stroke of the pump pistons 6, the solenoid valve 13 is opened and the fuel, which is kept at a higher pressure, passes from the suction chamber 12 into the pump work chamber 9. On the other end of the pump pistons, which projects into the engine chamber 2 and has the same area, the lower engine chamber pressure acts, so that the pistons are moved outwards by the pressure difference until they come into contact with the roller tappets on the cam track.

Wenn beim an den Saughub des Pumpenkolbens anschließend erfolgenden Förderhub durch Öffnen des Magnetventils 13 ein Teil des vom Pumpenkolben geförderten Kraftstoffs statt unter Hochdruck in die Einspritzdüsen nun in den Saugraum 12 über die Kanäle 10 und 11 zurückgefördert wird, kann die Membran 27 elastisch zum Triebwerksraum 2 hin ausweichen und damit den schnellen Druckabbau im Pumpenarbeitsraum 9 erleichtern.If, during the delivery stroke subsequent to the suction stroke of the pump piston, part of the fuel delivered by the pump piston is now conveyed back into the suction nozzles 12 via the channels 10 and 11 instead of under high pressure into the suction chamber 12, the membrane 27 can be elastic to the engine room 2 evade and thus facilitate the rapid pressure reduction in the pump work space 9.

Der Triebwerksraum 2 kann auch mit Schmiermittel, beispielsweise Motoröl gefüllt werden. In diesem Falle entfallen die Leitung 25 und die Drossel 26 und es muß eine gesonderte Einrichtung für die Zufuhr von Motoröl, zum Beispiel von der Brennkraftmaschine, unter entsprechendem Druck in den Triebwerksraum 2 vorgesehen werden.The engine room 2 can also be filled with lubricant, for example engine oil. In this case, the line 25 and the throttle 26 are omitted and a separate device for the supply of engine oil, for example from the internal combustion engine, must be provided in the engine compartment 2 under appropriate pressure.

Bei der Ausführungsform nach Figur 2 ist ein Stützkörper 29 vorgesehen, der mit der Zylinderbüchse 3 und der zylindrischen Gehäusewand 28 dicht verbunden ist. An seinen Umfängen weist der Stützkörper 29 Umfangsnuten 30 auf, in welche ein Dichtring 31 jeweils eingesetzt ist. An seiner zum Saugraum 12 weisenden Stirnseite weist der Stützkörper eine äußere Ringnut 32 und eine innere Ringnut 33 auf, in welche Dichtringe 34 und 35 eingelegt sind. Auf diesen Dichtringen 34 und 35 liegt eine flexible Platte bzw. eine Membran 36 auf, welche durch die Differenz des Drucks im Saugraum 12 und im Triebwerksraum 2 in ihrer Stellung gehalten wird. Der Stützkörper stützt sich unter Einwirkung des auf die Membran 36 wirkenden Differenzdrucks an einem Anschlag 44 an der zylindrischen Außenwand der Zylinderbüchse 3 ab.In the embodiment according to FIG. 2, a support body 29 is provided which is connected to the cylinder liner 3 and the cylindrical one Housing wall 28 is tightly connected. At its peripheries, the support body 29 has circumferential grooves 30, in which a sealing ring 31 is inserted. On its end facing the suction chamber 12, the support body has an outer annular groove 32 and an inner annular groove 33, in which sealing rings 34 and 35 are inserted. On these sealing rings 34 and 35 there is a flexible plate or membrane 36, which is held in its position by the difference in pressure in the suction chamber 12 and in the engine room 2. The support body is supported under the action of the differential pressure acting on the membrane 36 against a stop 44 on the cylindrical outer wall of the cylinder liner 3.

Bei der Ausführungsform nach Figur 3 ist die bewegliche Wand, welche den Saugraum 12 vom Triebwerksraum 2 trennt, von einem Kolben 37 gebildet. Dieser weist an seinem äußeren und inneren Umfang Ringnuten 38 und 39 auf, in welchen Dichtringe 40 und 41 angeordnet sind. Mittels dieser Dichtringe ist der Kolben 37, welcher axial verschiebbar ist, dicht an der zylindrischen Wand 28 und an der Zylinderbüchse 3 geführt. Der Kolben wird dabei zunächst von dem größeren Druck im Saugraum 12 an einen Anschlag 45 gehalten, der seinen Weg zum Triebwerksraum hin begrenzt. Der Anschlag kann dabei an der zylindrischen Gehäusewand, zum Beispiel als Sprengring, oder an der zylindrischen Außenwand der Zylinderbüchse 3 vorgesehen werden. Der Kolben kann sich dabei beim Auftreten von Druckwechseln in den angrenzenden Räumen 2 und 12 aus Anlaß der Ansteuer- und Füllvorgänge des Pumpenarbeitsraumes axial leicht hin- und herbewegen.In the embodiment according to FIG. 3, the movable wall, which separates the suction chamber 12 from the engine room 2, is formed by a piston 37. This has on its outer and inner circumference annular grooves 38 and 39, in which sealing rings 40 and 41 are arranged. By means of these sealing rings, the piston 37, which is axially displaceable, is guided close to the cylindrical wall 28 and to the cylinder liner 3. The piston is initially held by the greater pressure in the suction chamber 12 against a stop 45 which limits its path to the engine room. The stop can be provided on the cylindrical housing wall, for example as a snap ring, or on the cylindrical outer wall of the cylinder liner 3. The piston can move back and forth axially slightly when pressure changes occur in the adjacent rooms 2 and 12 due to the actuation and filling processes of the pump work space.

Claims (11)

  1. Fuel injection pump, especially fuel distributor injection pump, for internal combustion engines, having at least one pump piston (6) which is guided in a pump cylinder (7) and which, on one side, delimits a pump working space (9) and, on its other side, is connected operatively to a cam drive arranged in a driving-gear space (2) supplied with lubricating fluid, for the execution of pumping and suction strokes, having a movable wall (27) which encloses, within the fuel injection pump, a fuel-filled suction space (12) supplied from a fuel source and which separates said suction space from the driving-gear space (2), out of which suction space (12) fuel is delivered to the pump working space (9) during the suction stroke of the pump piston (6) and into which space, under the control of a solenoid valve (13) which is arranged in a relief duct (16) of the pump working space (9), residual fuel fed by the pump piston (6) is relieved, starting from the end of an injection-active controlled feed stroke of the pump piston, characterized in that the pump cylinder (7) is arranged with its axis in a radial plane (8) of a rotary-driven distributor (4) which is guided in a cylinder liner (3) inserted in the housing of the fuel injection pump, and there is arranged in the radial plane (8), in which the pump cylinder (7) lies with its axis, a cam ring (18) which surrounds the distributor (4) and has a cam track (17) which faces the pump piston (6), projecting out of the pump cylinder (7), and between which and the pump piston is arranged a pump tappet (15), and in that, when the fuel injection pump is in operation, the fuel pressure in the suction space (12) is always higher than the fluid pressure in the driving-gear space (2), so that the pump piston follows the cam track (17) as a result of the pressure difference between the suction-space pressure and the driving-gear-space pressure.
  2. Fuel injection pump according to Claim 1, characterized in that the movable wall (27, 36, 37) consists of an annular part arranged in a cylindrical annular space which is coaxial to the axis of the distributor (4) and which is at least part of the suction space (12) and of the driving-gear space (2).
  3. Fuel injection pump according to Claim 2, characterized in that the annular space is formed by the outer wall of the cylinder liner (3) and the circular-cylindrical inner wall of the housing (1) of the fuel injection pump, the said housing receiving the driving gear.
  4. Fuel injection pump according to Claims 1 to 3, characterized in that the movable wall is an elastically deformable wall (27, 36).
  5. Fuel injection pump according to Claims 1 to 3, characterized in that the movable wall is a piston part (37) displaceable along the cylindrical walls of the annular space.
  6. Fuel injection pump according to Claims 1 to 3, characterized in that the movable wall bears, so as to support itself, on a supporting body (29) which is guided between the cylindrical walls of the annular space.
  7. Fuel injection pump according to Claim 6, characterized in that the supporting body (29) has two annular end-face grooves (32, 38) which face the suction space and in which are arranged sealing rings, on which the elastically deformable wall (36) comes to bear as a result of the difference between the pressure in the suction space (12) and the pressure in the driving-gear space (2).
  8. Fuel injection pump according to Claim 5, characterized in that the movable wall (37) has annular grooves (38, 39) which face the walls of the annular space and in each of which a sealing ring (40, 41) is inserted.
  9. Fuel injection pump according to one of the preceding claims, characterized in that, on the same side as the cam space, the movable wall is held at least indirectly in bearing contact on at least one of the cylindrical walls of the annular space as a result of the difference between the pressure in the suction space (12) and the pressure in the cam space (2).
  10. Fuel injection pump according to one of the preceding claims, characterized in that the driving-gear space (2) is filled with fuel.
  11. Fuel injection pump according to one of the preceding Claims 1 to 10, characterized in that the driving-gear space (2) is filled with lubricating oil.
EP94105647A 1993-05-11 1994-04-13 Fuel injection pump for internal combustion engines Expired - Lifetime EP0633398B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4315646 1993-05-11
DE4315646A DE4315646A1 (en) 1993-05-11 1993-05-11 Fuel injection pump for internal combustion engines

Publications (2)

Publication Number Publication Date
EP0633398A1 EP0633398A1 (en) 1995-01-11
EP0633398B1 true EP0633398B1 (en) 1997-07-09

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EP94105647A Expired - Lifetime EP0633398B1 (en) 1993-05-11 1994-04-13 Fuel injection pump for internal combustion engines

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US (1) US5383436A (en)
EP (1) EP0633398B1 (en)
JP (1) JPH06330831A (en)
DE (2) DE4315646A1 (en)

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JPH07269439A (en) * 1994-03-31 1995-10-17 Zexel Corp Distribution type fuel injection pump
DE19531811A1 (en) * 1995-08-30 1997-03-06 Bosch Gmbh Robert Fuel injection pump
US5887569A (en) * 1997-07-17 1999-03-30 Pacer Industries, Inc. Centrifugal fuel distributor
DE19953576C2 (en) * 1999-11-08 2003-06-26 Bosch Gmbh Robert bearing bush
DE10060813A1 (en) * 2000-12-07 2002-06-20 Bosch Gmbh Robert Bearing surface on component which moves relative to another with gas or liquid between has surface with protrusions which produce pressure gradient in gas or liquid, preventing components from approaching each other too closely
US9897056B1 (en) 2016-11-22 2018-02-20 GM Global Technology Operations LLC Protective cover assembly for a fuel pump

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Publication number Priority date Publication date Assignee Title
FR2165220A5 (en) * 1971-12-22 1973-08-03 Roto Diesel Sa
GB2053372B (en) * 1979-07-06 1983-03-02 Lucas Industries Ltd Liquid fuel pumping apparatus
DE3011831A1 (en) * 1980-03-27 1981-10-01 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES
US4453896A (en) * 1980-12-17 1984-06-12 The Bendix Corporation Distributor pump with floating piston single control valve
US4357925A (en) * 1980-12-17 1982-11-09 The Bendix Corporation Distributor injection pump for diesel engines
GB8410280D0 (en) * 1984-04-19 1984-05-31 Lumber P M P Rotary distributor pump
DE3419828A1 (en) * 1984-05-26 1985-11-28 Robert Bosch Gmbh, 7000 Stuttgart Fuel injection pump
GB8417860D0 (en) * 1984-07-13 1984-08-15 Lucas Ind Plc Fuel injection pumping apparatus
GB8417861D0 (en) * 1984-07-13 1984-08-15 Lucas Ind Plc Fuel pumping apparatus
DE3719831A1 (en) * 1987-06-13 1988-12-22 Bosch Gmbh Robert FUEL INJECTION PUMP
US4915592A (en) * 1987-08-10 1990-04-10 Nippondenso Co., Ltd. Inner-cam type distribution fuel injection pump
GB8724795D0 (en) * 1987-10-22 1987-11-25 Lucas Ind Plc Fuel injection pump
DE3928613A1 (en) * 1989-08-30 1991-03-07 Bosch Gmbh Robert ELECTROMAGNETIC CONTROL VALVE
DE3928612A1 (en) * 1989-08-30 1991-03-07 Bosch Gmbh Robert FUEL DISTRIBUTOR INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES
US5215060A (en) * 1991-07-16 1993-06-01 Stanadyne Automotive Corp. Fuel system for rotary distributor fuel injection pump
US5265576A (en) * 1993-01-08 1993-11-30 Stanadyne Automotive Corp. Calibration system for electrically controlled fuel injection pump

Also Published As

Publication number Publication date
EP0633398A1 (en) 1995-01-11
US5383436A (en) 1995-01-24
DE59403283D1 (en) 1997-08-14
JPH06330831A (en) 1994-11-29
DE4315646A1 (en) 1994-11-17

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