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EP0370263B1 - Pumping element of a fuel injection pump for internal-combustion engines - Google Patents

Pumping element of a fuel injection pump for internal-combustion engines Download PDF

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Publication number
EP0370263B1
EP0370263B1 EP89119886A EP89119886A EP0370263B1 EP 0370263 B1 EP0370263 B1 EP 0370263B1 EP 89119886 A EP89119886 A EP 89119886A EP 89119886 A EP89119886 A EP 89119886A EP 0370263 B1 EP0370263 B1 EP 0370263B1
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EP
European Patent Office
Prior art keywords
piston
pump
suction
delivery
pump piston
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP89119886A
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German (de)
French (fr)
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EP0370263A1 (en
Inventor
Stanislaw Dr. Dipl.-Ing. Bodzak
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP0370263A1 publication Critical patent/EP0370263A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20—Varying fuel delivery in quantity or timing
    • F02M59/24—Varying fuel delivery in quantity or timing with constant-length-stroke pistons having variable effective portion of stroke
    • F02M59/26—Varying fuel delivery in quantity or timing with constant-length-stroke pistons having variable effective portion of stroke caused by movements of pistons relative to their cylinders
    • F02M59/265—Varying fuel delivery in quantity or timing with constant-length-stroke pistons having variable effective portion of stroke caused by movements of pistons relative to their cylinders characterised by the arrangement or form of spill port of spill contour on the piston
    • 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
    • F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
    • F02M59/442—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston means preventing fuel leakage around pump plunger, e.g. fluid barriers

Definitions

  • the invention relates to a pump element of a fuel injection pump for injection internal combustion engines, in which the pump piston liner has at least one suction and overflow bore, which is ground over by control edges of the pump piston and the end of delivery is determined by opening the suction and overflow bore, one in the area of the piston face
  • the control edge arranged determines the start of delivery and a control edge arranged, in particular, at an angle, determines the end of the delivery, with leakage fuel being introduced into the suction and overflow bore before and / or during the opening of the suction and overflow bore by the control edge determining the delivery end, and in the jacket of the pump piston, a leakage fuel collecting groove surrounding the pump piston is arranged below the control edge which determines the delivery end.
  • a pump element of the generic type is known from FR-A-843 031.
  • the hole in the pump piston serves, which opens via the transverse hole in the pump piston jacket to drain leakage fuel to the suction side of the fuel injection pump.
  • the invention is based on the problem, starting from the problem described at the outset, to make the expulsion effect exerted on the gas or vapor bubbles more intense and thereby counteract such cavitations and erosions better.
  • this fuel jet emerging through the transverse bore is directed in the direction of the axis of the suction and overflow bore, it exerts an intensive conveying effect on the gas or vapor bubbles.
  • this fuel entering through the transverse bore is leak fuel, the pressure is substantially lower than the pressure of the fuel entering the suction and overflow bore at the end of delivery and the gas bubbles are therefore not imploded.
  • the gas or vapor bubbles are only transported away from the critical point before they can be imploded by the high overflow pressure at the end of the delivery.
  • the leak oil fuel must be removed from the leak fuel catch groove. In known designs, this requires a drain hole in the pump piston liner, which weakens the pump piston liner and represents a risk of breakage.
  • the leakage fuel collecting groove extends as an annular groove over the entire circumference of the piston, the leakage fuel is collected in the same way over the entire piston circumference and made usable as flushing fuel.
  • the fuel is also under high pressure and because the leakage fuel collecting groove is arranged below a groove or recess in the piston, which is delimited at the top by the control edge that determines the end of delivery, the entire leaked fuel arrives into the leakage fuel collecting groove and is used for purging.
  • the arrangement of two opposite suction and overflow bores in the pump piston liner allows the transverse bore to be continuous so that both suction and overflow bores are flushed.
  • the arrangement is expediently such that the central region of the continuous transverse bore is connected to the leakage fuel collecting groove via an oblique bore. This ensures that both suction and overflow bores are flushed evenly.
  • the transverse bore expediently opens into a recess, for example a groove or a bevel, of the piston jacket which extends approximately parallel to the control edge which determines the end of the delivery.
  • a recess for example a groove or a bevel
  • the recess can also only extend over an arc region which corresponds to part of the maximum angle of rotation of the piston. It can be advantageous to make the flushing intensive only for certain injection quantities. The injection quantities are determined by the angle of rotation of the piston and if the recess extends only over an arc area, the flushing can be limited to certain filling and power ranges.
  • the transverse bore is expediently just above the control edge which determines the end of the delivery, that it is still in connection with the suction and overflow bore, preferably in its entirety, when the control edge which determines the end of the delivery opens the suction and overflow bore. In this way, the flushing is maintained at the beginning of the overflow at the end of the delivery.
  • the gap between the pump piston and pump piston liner is made in such a way that the gap in the area above the leakage fuel collecting groove is approximately five ten thousandths to approximately one thousandth of the piston diameter larger than in the area below it.
  • FIG. 1 shows an axial section through the pump piston and pump piston liner in an embodiment with two suction and overflow bores lying opposite one another in the pump piston liner.
  • Fig. 2 schematically indicates the expansion of the pump piston liner under the delivery pressure and the flow directions.
  • the pump piston 1 is guided in the pump piston sleeve 2 to move up and down.
  • the upper end face 3 of the pump piston 1 is acted upon by the high pressure in its working space 4.
  • the pump piston liner has mutually opposite suction and overflow bores 5 and 6, which open into the suction chamber.
  • the pump piston 1 moves upwards during its delivery stroke.
  • the edge 7 of the upper end face 3 determines the start of delivery by grinding the suction and overflow bores 5, 6.
  • the oblique control edges 8 of the pump piston 1 determine the end of the delivery by grinding the suction and overflow bores 5, 6.
  • the working space 4 of the pump piston 1 is connected to a recess 10 in the pump piston, which is delimited at the top by the control edge 8 determining the delivery end and at the bottom by an edge 11 below which the piston 1 has its full diameter in the region 12 .
  • a leakage fuel collecting groove 13 is arranged below the recess 10 on the piston skirt 14 and runs as an annular groove around the piston skirt.
  • a transverse bore 15 is provided in the piston 1, which is connected to the leakage fuel collecting groove 13 via an oblique bore 16 in the piston 1.
  • This oblique bore 16 opens into the transverse bore 15 in one Middle region 17 of the same.
  • the orifices 18 of the transverse bore 15 lie in those areas of the piston skirt 14 which overlap the suction and overflow bores 5, 6 of the pump piston liner 2. The fuel that accumulates in the leakage fuel collecting groove thus enters the suction and overflow bores 5, 6 via this transverse bore 15.
  • the transverse bore 15 opens into recesses 19 in the piston skirt 14, which are formed by grooves or bevels which run parallel to the control edge 8 which determines the end of the delivery.
  • these recesses 19 extend over the entire arc area, which corresponds to the maximum angle of rotation of the piston. However, they can also be limited to only a part of this arc area, as a result of which the entry of the leakage fuel into the suction and overflow bores is restricted to certain areas of rotation of the piston or delivery areas.
  • a plurality of diametrically arranged transverse bores 15 can also be advantageously arranged.
  • the mouths 18 of the transverse bore 15 grind over the suction and overflow bores 5, 6 before the control edges 8 determining the conveying end grind over these suction and overflow bores 5, 6 and the leakage fuel jet emerging through the cross bore 15 therefore promotes the gas and vapor bubbles in the direction of Suction chamber 20 before they can implode due to the high-tension fuel emerging via the control edges 8.
  • the transverse bore 15 is arranged just above the control edges 8 that determine the end of the delivery, that its mouths 18 or recesses 19 are still connected to the suction and overflow bores 5, 6 when the main outflow via the control edges 8 already begins.
  • the gap 21 between the pump piston 1 and the pump piston sleeve 2 is larger than in area b below the leak fuel collecting groove 13, where the gap has the size customary for pump elements.
  • the fuel is relieved below the leakage fuel collection groove 13, so that no more leakage fuel occurs below the leakage fuel collection groove 13.
  • the broken line 22 schematically indicates the widening of the bore or the piston running surface of the pump piston liner 2. This widening is lower in the upper region 22 ', since in this upper region the pump piston liner 2 is supported against the pressure valve body, not shown, and is thereby hindered in its radial expansion. In the lower area 22 ⁇ , this widening also becomes smaller again, since this area is relieved of pressure by the leakage fuel collecting groove 13. In the middle area, this widening can amount to 10 ⁇ m, for example.
  • the outer circumference of the pump piston liner 2 can also widen slightly, and this is indicated by the dashed line 25.
  • the gap length c is decisive for the amount of leakage fuel flowing through. This gap length c can be selected depending on the peak pressure and the delivery rate of the pump so that the leaked fuel quantity flowing through reaches the desired value.
  • the element play for elements with a diameter of 20 to 30 mm in the unloaded state is approximately 4 to 6 ⁇ m and increases under a pump chamber pressure of 1000 bar to approximately 14 to 16 ⁇ m, based on the diameter.
  • a favorable increase in the leakage quantity and thus the flushing quantity with an element diameter of 20 mm can be achieved.
  • the diameter difference can be about one thousandth to two thousandths of the piston diameter.
  • the arrow 23 indicates the start of the overflow when the control edge 8 the suction and overflow bores 5 and 6 smooth over.
  • the arrow 24 indicates the direction of the leakage fuel jet emerging through the transverse bore.

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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

Die Erfindung bezieht sich auf ein Pumpenelement einer Brennstoffeinspritzpumpe für Einspritzbrennkraftmaschinen, bei welchem die Pumpenkolbenbüchse wenigstens eine Saug- und Überströmbohrung aufweist, die durch Steuerkanten des Pumpenkolbens überschliffen wird und das Förderende durch Aufsteuern der Saug- und Überströmbohrung bestimmt wird, wobei eine im Bereich der Kolbenstirnfläche angeordnete Steuerkante den Förderbeginn und eine am Kolbenmantel angeordnete, insbesondere schräge, Steuerkante das Förderende bestimmt, wobei vor und/oder während beginnender Aufsteuerung der Saug- und Überströmbohrung durch die das Förderende bestimmende Steuerkante Leckkraftstoff in die Saug- und Überströmbohrung eingeführt wird und wobei im Mantel des Pumpenkolbens unterhalb der das Förderende bestimmenden Steuerkante eine den Pumpenkolben rundum umgebende Leckkraftstoffauffangnut angeordnet ist. Durch den plötzlichen Abschluß der Saug- und Überströmbohrung bei Förderbeginn bilden sich Gas- oder Dampfblasen in der Saug- und Überströmbohrung. Durch den Pumpenkolben wird der Kraftstoff im Arbeitsraum der Pumpe auf sehr hohe Drücke von beispielsweise 1000 bar und auch mehr gebracht und bei Förderende strömt dieser hochkomprimierte Kraftstoff in die Saug- und Überströmbohrung. Durch die Drucksteigerung in Saug- und Überströmbohrung implodieren diese Gas- oder Dampfblasen und es werden dadurch Kavitationen und Erosionen an der Wandung der Saug- und Überströmbohrung und auch am Kolbenmantel und an der Steuerkante verursacht.The invention relates to a pump element of a fuel injection pump for injection internal combustion engines, in which the pump piston liner has at least one suction and overflow bore, which is ground over by control edges of the pump piston and the end of delivery is determined by opening the suction and overflow bore, one in the area of the piston face The control edge arranged determines the start of delivery and a control edge arranged, in particular, at an angle, determines the end of the delivery, with leakage fuel being introduced into the suction and overflow bore before and / or during the opening of the suction and overflow bore by the control edge determining the delivery end, and in the jacket of the pump piston, a leakage fuel collecting groove surrounding the pump piston is arranged below the control edge which determines the delivery end. Due to the sudden completion of the suction and overflow bores at the start of delivery, gas or vapor bubbles form in the suction and overflow bores. The pump piston brings the fuel in the working area of the pump to very high pressures of, for example, 1000 bar and more, and at the end of delivery this highly compressed fuel flows into the suction and overflow bore. Due to the pressure increase in the suction and overflow bore, these gas or vapor bubbles implode and cavitation and erosion are caused on the wall of the suction and overflow bore and also on the piston skirt and on the control edge.

Aus der DE-OS 28 07 808 ist es bekannt geworden, Leckkraftstoff in die Saug- und Überströmbohrung einzuführen, um die Gas- oder Dampfblasen wegzufördern. Dieser Leckkraftstoff wird dadurch der Saug- und Überströmbohrung zugeführt, daß das Spiel zwischen dem Pumpenkolbenmantel und der Lauf fläche der Pumpenkolbenbüchse von der Stirnfläche des Pumpenkolbens bis zu der das Förderende bestimmenden Förderkante vergrößert wird. Dieser Leckkraftstoff kriecht entlang des gesamten Umfanges des Pumpenkolbens und tritt aus dem Spalt zwischen Pumpenkolben und Pumpenkolbenbüchse in die Saug- und Überströmbohrung ein. Er gelangt daher wohl in die Saug- und Überströmbohrung, jedoch nicht in gerichtetem Strahl, so daß seine auf die Gasblasen ausgeübte Förderwirkung nur einen sehr mangelhaften Effekt hat.From DE-OS 28 07 808 it has become known to introduce leakage fuel into the suction and overflow bore in order to convey away the gas or vapor bubbles. This leakage fuel is fed to the suction and overflow bore in that the play between the pump piston jacket and the barrel area of the pump piston bushing is increased from the end face of the pump piston to the conveyor edge which determines the end of the delivery. This leakage fuel creeps along the entire circumference of the pump piston and enters the suction and overflow bore from the gap between the pump piston and the pump piston sleeve. It therefore gets into the suction and overflow bore, but not in a directed jet, so that its conveying effect on the gas bubbles has only a very poor effect.

Aus der DE-OS 28 02 510 ist es bekannt geworden, den Leckkraftstoff in einer im Mantel des Pumpenkolbens oder in der Bohrung der Pumpenkolbenbüchse vorgesehenen, den Pumpenkolben rundum umgebenden Leckkraftstoffauffangnut zu sammeln und diese Leckkraftstoffauffangnut über eine Verbindungsbohrung in der Pumpenkolbenbüchse mit der Saug- und Überströmöffnung zu verbinden. Die Mündung dieser Verbindungsbohrung in die Saug- und Überströmbohrung ist in Richtung zur Kolbenwandung gerichtet, und der aus dieser Mündung austretende Leckkraftstoffstrahl unterstützt daher die Wegförderung der Gas- oder Dampfblasen aus der Saug- und Überströmbohrung nicht, sondern wirkt eher dieser Wegförderung entgegen.From DE-OS 28 02 510 it is known to collect the leak fuel in a provided in the jacket of the pump piston or in the bore of the pump piston sleeve, surrounding the pump piston leak fuel collecting groove and this leak fuel collecting groove via a connecting hole in the pump piston sleeve with the suction and To connect overflow opening. The mouth of this connecting hole in the suction and overflow hole is directed towards the piston wall, and the leakage fuel jet emerging from this mouth therefore does not support the removal of gas or vapor bubbles from the suction and overflow hole, but rather counteracts this removal.

Durch die FR-A-843 031 ist ein Pumpenelement der gattungsgemäßen Art bekannt. Dort dient die Bohrung im Pumpenkolben, die über die Querbohrung im Pumpenkolbenmantel mündet der Ableitung von Leckkraftstoff zur Saugseite der Kraftstoffeinspritzpumpe .A pump element of the generic type is known from FR-A-843 031. There, the hole in the pump piston serves, which opens via the transverse hole in the pump piston jacket to drain leakage fuel to the suction side of the fuel injection pump.

Der Erfindung liegt dagegen die Aufgabe zugrunde, ausgehend von der eingangs geschilderten Problematik, die auf die Gas- oder Dampfblasen ausgeübte Wegförderwirkung intensiver zu gestalten und dadurch solchen Kavitationen und Erosionen besser entgegen zu wirken.On the other hand, the invention is based on the problem, starting from the problem described at the outset, to make the expulsion effect exerted on the gas or vapor bubbles more intense and thereby counteract such cavitations and erosions better.

Diese Aufgabe wird gemäß der Erfindung durch die kennzeichnenden Merkmale des Patentanspruchs 1 gelöst. Die Begriffe "unterhalb" und "oberhalb" sind auf die obere vom Hochdruck beaufschlagte Stirnfläche des Pumpenkolbens unabhängig von der Einbaulage des Pumpenelementes bezogen. Durch diese Querbohrung gelangt nun Leckkraftstoff in gerichtetem Strom in die Saug- und Überströmbohrung, bevor der unter hohem Druck abgesteuerte Kraftstoff in die Saug- und Überströmbohrung eintritt. Der Druck dieses Leckkraftstoffstrahles ist größer als der Druck im Saugraum und es werden daher die Gas- oder Dampfblasen von der kritischen Stelle in der Saug- und Überströmbohrung weg zum Saugraum gefördert. Da dieser durch die Querbohrung austretende Brennstoffstrahl in Richtung der Achse der Saug- und Überströmbohrung gerichtet ist, übt er eine intensive Förderwirkung auf die Gas- oder Dampfblasen aus. Da es sich aber bei diesem durch die Querbohrung eintretenden Kraftstoff um Leckkraftstoff handelt, ist der Druck wesentlich geringer als der Druck des bei Förderende in die Saug- und Überströmbohrung eintretenden Kraftstoffes und es werden daher die Gasblasen nicht zum Implodieren gebracht. Die Gas- oder Dampfblasen werden nur von der kritischen Stelle weggefördert, bevor sie durch den hohen Überströmdruck bei Förderende zum Implodieren gebracht werden können. Der Leckölkraftstoff muß aus der Leckkraftstoffauffangnut abgefördert werden. Dies erfordert bei bekannten Ausführungen eine Abflußbohrung in der Pumpenkolbenbüchse, welche die Pumpenkolbenbüchse schwächt und eine Bruchgefahr darstellt. Dadurch, daß der Leckkraftstoff als Spülkraftstoff ausgenützt wird, entfällt eine solche Leckölabführbohrung in der Pumpenkolbenbüchse. Dadurch, daß sich die Leckkraftstoffauffangnut als Ringnut über den gesamten Umfang des Kolbens erstreckt, wird der Leckkraftstoff über den gesamten Kolbenumfang in gleicher Weise aufgefangen und als Spülkraftstoff nutzbar gemacht. Unterhalb der das Förderende bestimmenden Steuerkante im Bereich der Saug- und Überströmbohrung steht der Kraftstoff auch unter Hochdruck und dadurch, daß die Leckkraftstoffauffangnut unterhalb einer Nut oder Ausnehmung im Kolben angeordnet ist, welche oben durch die das Förderende bestimmende Steuerkante begrenzt ist, gelangt der gesamte Leckkraftstoff in die Leckkraftstoffauffangnut und wird für die Spülung nutzbar gemacht.This object is achieved according to the invention by the characterizing features of patent claim 1. The terms "below" and "above" are related to the upper face of the pump piston, which is acted upon by high pressure, regardless of the installation position of the pump element. Through this transverse bore, leaked fuel now flows in a directed flow into the suction and overflow bore before the fuel, which is controlled under high pressure, enters the suction and overflow bore. The pressure of this leakage fuel jet is greater than the pressure in the suction chamber and therefore the gas or vapor bubbles are conveyed away from the critical point in the suction and overflow bore to the suction chamber. Since this fuel jet emerging through the transverse bore is directed in the direction of the axis of the suction and overflow bore, it exerts an intensive conveying effect on the gas or vapor bubbles. However, since this fuel entering through the transverse bore is leak fuel, the pressure is substantially lower than the pressure of the fuel entering the suction and overflow bore at the end of delivery and the gas bubbles are therefore not imploded. The gas or vapor bubbles are only transported away from the critical point before they can be imploded by the high overflow pressure at the end of the delivery. The leak oil fuel must be removed from the leak fuel catch groove. In known designs, this requires a drain hole in the pump piston liner, which weakens the pump piston liner and represents a risk of breakage. Because the leak fuel is used as flushing fuel, there is no need for such a leak oil drain hole in the pump piston liner. Characterized in that the leakage fuel collecting groove extends as an annular groove over the entire circumference of the piston, the leakage fuel is collected in the same way over the entire piston circumference and made usable as flushing fuel. Below the control edge that determines the end of the delivery in the area of the suction and overflow bore, the fuel is also under high pressure and because the leakage fuel collecting groove is arranged below a groove or recess in the piston, which is delimited at the top by the control edge that determines the end of delivery, the entire leaked fuel arrives into the leakage fuel collecting groove and is used for purging.

Gemäß der Erfindung kann bei Anordnung von zwei gegenüberliegenden Saug- und Überströmbohrungen in der Pumpenkolbenbüchse die Querbohrung durchgehend sein, so daß beide Saug- und Überströmbohrungen gespült werden. Hiebei ist die Anordnung zweckmäßig so getroffen, daß der Mittelbereich der durchgehenden Querbohrung über eine schräge Bohrung mit der Leckkraftstoffauffangnut in Verbindung steht. Hiedurch wird eine gleichmäßige Spülung beider Saug- und Überströmbohrungen gewährleistet.According to the invention, the arrangement of two opposite suction and overflow bores in the pump piston liner allows the transverse bore to be continuous so that both suction and overflow bores are flushed. The arrangement is expediently such that the central region of the continuous transverse bore is connected to the leakage fuel collecting groove via an oblique bore. This ensures that both suction and overflow bores are flushed evenly.

Gemäß der Erfindung mündet zweckmäßig die Querbohrung in eine Ausnehmung, beispielsweise eine Nut oder einen Anschliff, des Kolbenmantels, welche sich ungefähr parallel zu der das Förderende bestimmenden Steuerkante erstreckt. Auf diese Weise wird die Spülung auch bei einer Verdrehung des Kolbens aufrecht erhalten. Gemäß der Erfindung kann sich aber auch die Ausnehmung nur über einen Bogenbereich erstrecken, welcher einem Teil des maximalen Verdrehwinkels des Kolbens entspricht. Es kann vorteilhaft sein, die Spülung nur bei bestimmten Einspritzmengen intensiv zu gestalten. Die Einspritzmengen werden durch den Verdrehwinkel des Kolbens bestimmt und wenn sich die Ausnehmung nur über einen Bogenbereich erstreckt, kann die Spülung auf gewisse Füllungs- und Leistungsbereiche beschränkt werden.According to the invention, the transverse bore expediently opens into a recess, for example a groove or a bevel, of the piston jacket which extends approximately parallel to the control edge which determines the end of the delivery. In this way, the flushing is maintained even when the piston is turned. According to the invention, however, the recess can also only extend over an arc region which corresponds to part of the maximum angle of rotation of the piston. It can be advantageous to make the flushing intensive only for certain injection quantities. The injection quantities are determined by the angle of rotation of the piston and if the recess extends only over an arc area, the flushing can be limited to certain filling and power ranges.

Gemäß der Erfindung liegt zweckmäßig die Querbohrung so knapp über der das Förderende bestimmenden Steuerkante, daß sie noch mit der Saug- und Überströmbohrung, vorzugsweise zur Gänze, in Verbindung steht, wenn die das Förderendebestimmende Steuerkante die Saug- und Überströmbohrung aufsteuert. Auf diese Weise wird die Spülung noch zu Beginn der Überströmung bei Förderende aufrecht erhalten.According to the invention, the transverse bore is expediently just above the control edge which determines the end of the delivery, that it is still in connection with the suction and overflow bore, preferably in its entirety, when the control edge which determines the end of the delivery opens the suction and overflow bore. In this way, the flushing is maintained at the beginning of the overflow at the end of the delivery.

Für eine gezielle Spülung wird gemäß der Erfindung der Spalt zwischen Pumpenkolben und Pumpenkolbenbüchse so getroffen, daß der Spalt im Bereich oberhalb der Leckkraftstoffauffangnut um ungefähr fünf Zehntausendstel bis etwa ein Tausendstel des Kolbendurchmessers größer ist als im Bereich unterhalb derselben.For a targeted flushing, the gap between the pump piston and pump piston liner is made in such a way that the gap in the area above the leakage fuel collecting groove is approximately five ten thousandths to approximately one thousandth of the piston diameter larger than in the area below it.

Figurenbeschreibung:Figure description:

In der Zeichnung ist die Erfindung anhand eines Ausführungsbeispieles erläutert.In the drawing, the invention is explained using an exemplary embodiment.

Fig. 1 zeigt einen Axialschnitt durch Pumpenkolben und Pumpenkolbenbüchse bei einer Ausführungsform mit zwei einander gegenüberliegenden Saug- und Überströmbohrungen in der Pumpenkolbenbüchse. Fig. 2 deutet schematisch die Erweiterung der Pumpenkolbenbüchse unter dem Förderdruck und die Strömungsrichtungen an.1 shows an axial section through the pump piston and pump piston liner in an embodiment with two suction and overflow bores lying opposite one another in the pump piston liner. Fig. 2 schematically indicates the expansion of the pump piston liner under the delivery pressure and the flow directions.

Der Pumpenkolben 1 ist in der Pumpenkolbenbüchse 2 zu auf- und abgehender Bewegung geführt. Die obere Stirnfläche 3 des Pumpenkolbens 1 ist vom Hochdruck in seinem Arbeitsraum 4 beaufschlagt. Die Pumpenkolbenbüchse weist einander gegenüberliegende Saug- und Überströmbohrungen 5 und 6 auf, welche in den Saugraum münden. Der Pumpenkolben 1 bewegt sich bei seinem Förderhub nach oben. Die Kante 7 der oberen Stirnfläche 3 bestimmt durch Überschleifen der Saug- und Überströmbohrungen 5, 6 den Förderbeginn. Die schrägen Steuerkanten 8 des Pumpenkolbens 1 bestimmen durch Überschleifen der Saug- und Überströmbohrungen 5, 6 das Förderende. Über eine Axialnut 9 steht der Arbeitsraum 4 des Pumpenkolbens 1 mit einer Ausnehmung 10 im Pumpenkolben in Verbindung, welche oben durch die das Förderende bestimmende Steuerkante 8 und unten durch eine Kante 11 begrenzt wird, unterhalb welcher der Kolben 1 im Bereich 12 seinen vollen Durchmesser aufweist.The pump piston 1 is guided in the pump piston sleeve 2 to move up and down. The upper end face 3 of the pump piston 1 is acted upon by the high pressure in its working space 4. The pump piston liner has mutually opposite suction and overflow bores 5 and 6, which open into the suction chamber. The pump piston 1 moves upwards during its delivery stroke. The edge 7 of the upper end face 3 determines the start of delivery by grinding the suction and overflow bores 5, 6. The oblique control edges 8 of the pump piston 1 determine the end of the delivery by grinding the suction and overflow bores 5, 6. Via an axial groove 9, the working space 4 of the pump piston 1 is connected to a recess 10 in the pump piston, which is delimited at the top by the control edge 8 determining the delivery end and at the bottom by an edge 11 below which the piston 1 has its full diameter in the region 12 .

Unterhalb der Ausnehmung 10 ist eine Leckkraftstoffauffangnut 13 am Kolbenmantel 14 angeordnet, welche als Ringnut rundum den Kolbenmantel verläuft. Im Kolben 1 ist eine Querbohrung 15 vorgesehen, welche über eine Schrägbohrung 16 im Kolben 1 mit der Leckkraftstoffauffangnut 13 in Verbindung steht. Diese Schrägbohrung 16 mündet in die Querbohrung 15 in einem Mittelbereich 17 derselben. Die Mündungen 18 der Querbohrung 15 liegen in denjenigen Bereichen des Kolbenmantels 14, welche die Saug- und Überströmbohrungen 5, 6 der Pumpenkolbenbüchse 2 überschleifen. Über diese Querbohrung 15 gelangt somit der sich in der Leckkraftstoffauffangnut ansammelnde Kraftstoff in die Saug- und Überströmbohrungen 5, 6.A leakage fuel collecting groove 13 is arranged below the recess 10 on the piston skirt 14 and runs as an annular groove around the piston skirt. A transverse bore 15 is provided in the piston 1, which is connected to the leakage fuel collecting groove 13 via an oblique bore 16 in the piston 1. This oblique bore 16 opens into the transverse bore 15 in one Middle region 17 of the same. The orifices 18 of the transverse bore 15 lie in those areas of the piston skirt 14 which overlap the suction and overflow bores 5, 6 of the pump piston liner 2. The fuel that accumulates in the leakage fuel collecting groove thus enters the suction and overflow bores 5, 6 via this transverse bore 15.

Die Querbohrung 15 mündet in Ausnehmungen 19 des Kolbenmantels 14, welche von Nuten oder Anschliffen gebildet sind, welche parallel zu den das Förderende bestimmenden Steuerkante 8 verlaufen. Bei dem Ausführungsbeispiel der Zeichnung erstrecken sich diese Ausnehmungen 19 über den gesamten Bogenbereich, welcher dem maximalen Verdrehwinkel des Kolbens entspricht. Sie können aber auch nur auf einen Teil dieses Bogenbereiches beschränkt sein, wodurch der Eintritt des Leckkraftstoffes in die Saug- und Überströmbohrungen auf gewisse Verdrehbereiche des Kolbens oder Förderbereiche beschränkt wird. Zur Verbindung der Ausnehmungen 19 im Kolben 1 können günstig auch mehrere diametral angeordnete Querbohrungen 15 angeordnet werden.The transverse bore 15 opens into recesses 19 in the piston skirt 14, which are formed by grooves or bevels which run parallel to the control edge 8 which determines the end of the delivery. In the embodiment of the drawing, these recesses 19 extend over the entire arc area, which corresponds to the maximum angle of rotation of the piston. However, they can also be limited to only a part of this arc area, as a result of which the entry of the leakage fuel into the suction and overflow bores is restricted to certain areas of rotation of the piston or delivery areas. To connect the recesses 19 in the piston 1, a plurality of diametrically arranged transverse bores 15 can also be advantageously arranged.

Die Mündungen 18 der Querbohrung 15 überschleifen die Saug- und Überströmbohrungen 5, 6, bevor die das Förderende bestimmenden Steuerkanten 8 diese Saug- und Überströmbohrungen 5, 6 überschleifen und der durch die Querbohrung 15 austretende Leckkraftstoffstrahl fördert daher die Gas- und Dampfblasen in Richtung zum Saugraum 20, bevor sie durch den hochgespannten über die Steuerkanten 8 austretenden Kraftstoff implodieren können. Die Querbohrung 15 ist aber so knapp über den das Förderende bestimmenden Steuerkanten 8 angeordnet, daß ihre Mündungen 18 bzw. die Ausnehmungen 19 noch mit den Saug- und Überströmbohrungen 5, 6 in Verbindung stehen, wenn die Hauptausströmung über die Steuerkanten 8 bereits beginnt.The mouths 18 of the transverse bore 15 grind over the suction and overflow bores 5, 6 before the control edges 8 determining the conveying end grind over these suction and overflow bores 5, 6 and the leakage fuel jet emerging through the cross bore 15 therefore promotes the gas and vapor bubbles in the direction of Suction chamber 20 before they can implode due to the high-tension fuel emerging via the control edges 8. However, the transverse bore 15 is arranged just above the control edges 8 that determine the end of the delivery, that its mouths 18 or recesses 19 are still connected to the suction and overflow bores 5, 6 when the main outflow via the control edges 8 already begins.

Im Bereich a oberhalb der Leckkraftstoffauffangnut 13 bis zur oberen Stirnfläche 3 des Kolbens 1 ist der Spalt 21 zwischen Pumpenkolben 1 und Pumpenkolbenbüchse 2 größer als im Bereich b unterhalb der Leckkraftstoffauffangnut 13, wo der Spalt die bei Pumpenelementen übliche Größe aufweist. Unterhalb der Leckkraftstoffauffangnut 13 ist der Kraftstoff entlastet, so daß unterhalb der Leckkraftstoffauffangnut 13 kein Leckkraftstoff mehr auftritt.In the area a above the leak fuel collecting groove 13 up to the upper end face 3 of the piston 1, the gap 21 between the pump piston 1 and the pump piston sleeve 2 is larger than in area b below the leak fuel collecting groove 13, where the gap has the size customary for pump elements. The fuel is relieved below the leakage fuel collection groove 13, so that no more leakage fuel occurs below the leakage fuel collection groove 13.

Unter dem Förderdruck des Kraftstoffes vergrößert sich der Durchmesser der Pumpenkolbenbüchse 2 und damit die Größe des Spaltes 21 geringfügig, wie dies in Fig. 2 angedeutet ist. Die strichlierte Linie 22 deutet schematisch die Aufweitung der Bohrung bzw. der Kolbenlauffläche der Pumpenkolbenbüchse 2 an. Diese Aufweitung ist im oberen Bereich 22′ geringer, da in diesem oberen Bereich die Pumpenkolbenbüchse 2 gegen den nicht dargestellten Druckventilkörper abgestützt ist und dadurch in ihrer radialen Dehnung behindert wird. Im unteren Bereich 22˝ wird diese Aufweitung auch wieder geringer, da dieser Bereich durch die Leckkraftstoffauffangnut 13 druckentlastet ist. Im mittleren Bereich kann diese Aufweitung beispielsweise 10 µm betragen. Auch der Außenumfang der Pumpenkolbenbüchse 2 kann sich geringfügig aufweiten und dies ist mit der strichlierten Linie 25 angedeutet.Under the delivery pressure of the fuel, the diameter of the pump piston liner 2 and thus the size of the gap 21 increase slightly, as is indicated in FIG. 2. The broken line 22 schematically indicates the widening of the bore or the piston running surface of the pump piston liner 2. This widening is lower in the upper region 22 ', since in this upper region the pump piston liner 2 is supported against the pressure valve body, not shown, and is thereby hindered in its radial expansion. In the lower area 22˝, this widening also becomes smaller again, since this area is relieved of pressure by the leakage fuel collecting groove 13. In the middle area, this widening can amount to 10 µm, for example. The outer circumference of the pump piston liner 2 can also widen slightly, and this is indicated by the dashed line 25.

Die Spaltlänge c ist maßgebend für die durchströmende Leckkraftstoffmenge. Diese Spaltlänge c kann in Abhängigkeit vom Spitzendruck und der Fördermenge der Pumpe so gewählt werden, daß die durchströmende Leckkraftstoffmenge den gewünschten Wert erreicht.The gap length c is decisive for the amount of leakage fuel flowing through. This gap length c can be selected depending on the peak pressure and the delivery rate of the pump so that the leaked fuel quantity flowing through reaches the desired value.

Beispielsweise beträgt das Elementspiel bei Elementen mit Durchmesser 20 bis 30 mm in unbelastetem Zustand etwa 4 bis 6 µm und vergrößert sich unter einem Pumpenraumdruck von 1000 bar auf ca. 14 bis 16 µm, bezogen auf den Durchmesser. Durch eine Vergrößerung des gegebenen Ausgangsspiels im Bereich zwischen Ringnut 10 und Leckkraftstoffauffangnut 13 um etwa 2 mal 10 µm, bezogen auf die Durchmesserdifferenz, kann eine günstige Vergrößerung der Leckmenge und damit Spülmenge bei Elementdurchmesser 20 mm erreicht werden. Allgemeingültig kann die Durchmesserdifferenz etwa ein Tausendstel bis zwei Tausendstel des Kolbendurchmessers betragen.For example, the element play for elements with a diameter of 20 to 30 mm in the unloaded state is approximately 4 to 6 µm and increases under a pump chamber pressure of 1000 bar to approximately 14 to 16 µm, based on the diameter. By increasing the given initial play in the area between the ring groove 10 and the leakage fuel collecting groove 13 by approximately 2 × 10 μm, based on the difference in diameter, a favorable increase in the leakage quantity and thus the flushing quantity with an element diameter of 20 mm can be achieved. Generally speaking, the diameter difference can be about one thousandth to two thousandths of the piston diameter.

Der Pfeil 23 deutet den Beginn der Überströmung an, wenn die Steuerkante 8 die Saug- und Überströmbohrungen 5 und 6 überschleifen. Der Pfeil 24 deutet die Richtung des durch die Querbohrung austretenden Leckkraftstoffstrahles an.The arrow 23 indicates the start of the overflow when the control edge 8 the suction and overflow bores 5 and 6 smooth over. The arrow 24 indicates the direction of the leakage fuel jet emerging through the transverse bore.

Bezugszeichenliste :Reference symbol list:

11
PumpenkolbenPump piston
22nd
PumpenkolbenbüchsePump piston liner
33rd
obere Stirnfläche des Pumpenkolbensupper face of the pump piston
44th
Arbeitsraumworking space
55
Saug- und ÜberströmbohrungSuction and overflow drilling
66
Saug- und ÜberströmbohrungSuction and overflow drilling
77
Oberkante des KolbensTop edge of the piston
88th
schräge Steuerkantensloping control edges
99
Axialnut im KolbenAxial groove in the piston
1010th
Ausnehmung im Kolben unterhalb der Steuerkanten 8Recess in the piston below the control edges 8
1111
untere Begrenzung der Ausnehmung 10lower limit of the recess 10
1212
Kolbenbereich zwischen der Ausnehmung 10 und der Leckkraftstoffauffangnut 13Piston area between the recess 10 and the leak fuel collecting groove 13
1313
LeckkraftstoffauffangnutLeak fuel catch groove
1414
KolbenmantelPiston skirt
1515
Querbohrung im KolbenCross bore in the piston
1616
Schrägbohrung im KolbenOblique bore in the piston
1717th
Mittelbereich der Querbohrung 15Middle area of the transverse bore 15
1818th
Mündungen der Querbohrung 15Mouths of the cross hole 15
1919th
Ausnehmungen im Kolbenmantel an der Mündung der Querbohrung 15Recesses in the piston skirt at the mouth of the transverse bore 15
2020th
SaugraumSuction chamber
2121
Spalt zwischen Pumpenkolben und PumpenkolbenbüchseGap between pump piston and pump piston liner
2222
Deformierung der Innenwandung der PumpenkolbenbüchseDeformation of the inner wall of the pump piston liner
22′22 ′
Deformierung im oberen BereichDeformation in the upper area
22˝22˝
Deformierung unterhalb der LeckkraftstoffauffangnutDeformation below the leakage fuel collecting groove
2323
Richtungspfeil der ÜberströmungDirection arrow of the overflow
2424th
Richtungspfeil des LeckkraftstoffesDirectional arrow of the leak fuel
2525th
Deformierung des Außenumfanges der PumpenkolbenbüchseDeformation of the outer circumference of the pump piston liner
  • a Kolbenbereich zwischen Pumpenkolbenoberkante und Leckkraftstoffauffangnuta Piston area between the upper edge of the pump piston and the leakage fuel collecting groove
  • b Kolbenbereich unterhalb der Leckkraftstoffauffangnutb Piston area below the leak fuel groove
  • c Spaltlänge zwischen der Kolbenausnehmung 10 und der Leckkraftstoffauffangnut 13c gap length between the piston recess 10 and the leakage fuel collecting groove 13

Claims (8)

1. Pump element of a fuel injection pump for fuel injection internal combustion engines, in which the pump piston sleeve (2) has at least one suction and relief hole (5, 6) over which slide control edges (3, 8) of the pump piston (1) and the end of delivery is determined by activation of the suction and relief hole, wherein a control edge located in the region of the piston end surface (3) bounding the pump working space (4) in the pump element determines the beginning of delivery and a control edge (8), in particular an oblique one, located on the piston cylindrical surface (14) determines the end of delivery, wherein leakage fuel is introduced into the suction and relief hole (20) at least before the initial activation, by the control edge (8) determining the end of delivery, of the suction and relief hole and having a leakage fuel capture groove (13) located in the cylindrical surface of the pump piston below a groove or recess (10) in the piston (1) completely surrounding the pump piston (1), continually connected to the pump working space (4) and bounded at the top by the control edge (8) determining the end of delivery and at least one transverse hole (15) located in the pump piston (1) above the control edge (8) determining the end of delivery, which transverse hole (15) emerges on the piston cylindrical surface (14) in a region of the latter which slides over the suction and relief hole (5, 6) and which transverse hole (15) is connected to the leakage fuel capture groove (13) by means of a hole (16) in the pump piston, characterised in that the gap (21) between the pump piston (1) and the pump piston sleeve (2) is greater, at least in the region (c) between the leakage fuel capture groove (13) and the control edge (8) determining the end of delivery, than it is in the region (b) below the leakage fuel capture groove (13).
2. Pump element according to Claim 1, characterised in that the gap (21) is greater by approximately five ten-thousandths to approximately one thousandth of the piston diameter in the region (c) above the leakage fuel capture groove (13) than it is in the region (b) below the leakage fuel capture groove (13).
3. Pump element according to Claim 1 or 2, characterised in that in the case of the arrangement of two opposite suction and relief holes (5, 6) in the pump piston sleeve (2), the transverse hole (15) is continuous.
4. Pump element according to Claim 3, characterised in that the central region (17) of the continuous transverse hole (15) is connected to the leakage fuel capture groove (13) by means of an oblique hole (16).
5. Pump element according to Claim 1 or 4, characterised in that the transverse hole (15) emerges into a recess (19), for example a groove or a ground surface, in the piston cylindrical surface (14), which recess extends approximately parallel to the control edge (8) determining the end of delivery.
6. Pump element according to Claim 5, characterised in that the recess (19) only extends over an angular range corresponding to part of the maximum angle of rotation of the piston (1).
7. Pump element according to one of Claims 1 to 6, characterised in that the recess (19) is located so closely above the control edge (8) determining the end of delivery that it is still connected, preferably completely, to the suction and relief hole (5, 6) when the control edge (8) determining the end of delivery activates the suction and relief hole (5, 6).
8. Pump element according to one of Claims 1 to 7, characterised in that there are two or more continuous transverse holes (15) for connecting the recesses (19) in the pump piston (1).
EP89119886A 1988-11-25 1989-10-26 Pumping element of a fuel injection pump for internal-combustion engines Expired - Lifetime EP0370263B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3839753 1988-11-25
DE3839753A DE3839753A1 (en) 1988-11-25 1988-11-25 PUMP ELEMENT OF A FUEL INJECTION PUMP FOR INJECTION COMBUSTION ENGINES

Publications (2)

Publication Number Publication Date
EP0370263A1 EP0370263A1 (en) 1990-05-30
EP0370263B1 true EP0370263B1 (en) 1992-06-17

Family

ID=6367840

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89119886A Expired - Lifetime EP0370263B1 (en) 1988-11-25 1989-10-26 Pumping element of a fuel injection pump for internal-combustion engines

Country Status (3)

Country Link
EP (1) EP0370263B1 (en)
JP (1) JP2880205B2 (en)
DE (2) DE3839753A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006016702A1 (en) * 2006-04-08 2007-10-18 Man Diesel Se Piston pump for supplying fuel in fuel injection system of internal-combustion engine, has recesses provided in guiding area between pump cylinder and pump piston, where fuel is supplied into recesses in axial direction

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR843031A (en) * 1938-02-25 1939-06-23 Prec Mecanique S A Improvements to piston pumps, especially fuel injection pumps
DE1214934B (en) * 1962-02-12 1966-04-21 Friedmann & Maier Ag Injection pump for internal combustion engines
FR1401831A (en) * 1963-07-19 1965-06-04 Fiat Spa Improvements to fuel injection pumps for internal combustion piston engines
AT404058B (en) * 1986-09-10 1998-08-25 Bosch Robert Ag PUMP ELEMENT OF A FUEL INJECTION PUMP FOR INJECTION COMBUSTION ENGINES

Also Published As

Publication number Publication date
JPH02181066A (en) 1990-07-13
JP2880205B2 (en) 1999-04-05
DE58901694D1 (en) 1992-07-23
DE3839753A1 (en) 1990-05-31
EP0370263A1 (en) 1990-05-30

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