EP0150471B1 - Fuel-injection pump - Google Patents

Fuel-injection pump Download PDF

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Publication number
EP0150471B1
EP0150471B1 EP84116075A EP84116075A EP0150471B1 EP 0150471 B1 EP0150471 B1 EP 0150471B1 EP 84116075 A EP84116075 A EP 84116075A EP 84116075 A EP84116075 A EP 84116075A EP 0150471 B1 EP0150471 B1 EP 0150471B1
Authority
EP
European Patent Office
Prior art keywords
pump
fuel
distributor
piston
fuel injection
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
Application number
EP84116075A
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German (de)
French (fr)
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EP0150471A2 (en
EP0150471A3 (en
Inventor
Jean Leblanc
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Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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Filing date
Publication date
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Publication of EP0150471A2 publication Critical patent/EP0150471A2/en
Publication of EP0150471A3 publication Critical patent/EP0150471A3/en
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Publication of EP0150471B1 publication Critical patent/EP0150471B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M41/00—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor
    • F02M41/02—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor being spaced from pumping elements
    • F02M41/06—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor being spaced from pumping elements the distributor rotating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
    • F02M45/02—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
    • F02M45/04—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
    • F02M45/06—Pumps peculiar thereto
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • 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

Definitions

  • a fuel injection pump known from DE-C-18 07 554 is designed as a reciprocating piston distributor pump with a relief channel running in the pump piston and branching off from the pump work space, which has a lateral outlet on the pump piston and is connected to a relief line from a certain stroke position of the respective pump delivery stroke is connected to a discharge volume of constant content via a variable and a fixed throttle.
  • the capacity of this volume is determined on the one hand by the variable throttle, which is adjustable depending on the load, and on the other hand by the fixed throttle, which acts as a function of the speed.
  • the known device does not permit universal use and, in particular, the amount of a pre-injection before the actual main injection and the time interval between the pre-injection and the main injection cannot be determined over wide operating ranges of the internal combustion engine.
  • a distributor fuel injection pump is also known, in which, similarly to the distributor fuel injection pump mentioned at the beginning, part of the fuel delivered by the pump piston can be dispensed into a fuel removal space which is activated again with each fuel injection process of the distributor fuel injection pump.
  • this activation takes place with a fixed stroke of the pump piston or with a fixed rotational position of a distributor of the distributor fuel injection pump, the removal space consisting of a combination between a fixed volume accumulator and an escape piston connected upstream of this accumulator.
  • the distance covered by this decreases, which corresponds in each case to the effective receiving volume of the accumulator under the action of a throttle which restricts the return movement of the piston.
  • a reduction in the injection rate and thus also the injection quantity is achieved over the duration of the total injection time.
  • the device is only effective within a single speed range.
  • a fuel injection pump is also known from FR-C-1 495 537, in which the pump work space is continuously connected to a fuel extraction space via a throttle. This is limited by an evasive piston, the evasive movement of which can be blocked by an additional device in a certain operating range of the internal combustion engine in such a way that the removal function of the fuel removal space is canceled.
  • the fuel injection rate is reduced over part of the delivery stroke of the pump piston.
  • a fuel injection pump of the generic type is known from DE-C-585 014.
  • the movable wall executes its stroke up to the adjustable stop with each actuation process of the relief opening, a certain fixed quantity of fuel being taken from the quantity of fuel delivered by the pump piston.
  • the point in time at which the fuel injection is interrupted during the course of the injection can be varied as a function of the main injection quantity. If the start of delivery remains the same, the fuel pre-injection quantity decreases as the load decreases. With such a fuel injection pump, the amount of pre-injection can therefore only be controlled in a very specific law. Furthermore, the distance between the pre-injection and the main injection is determined by the withdrawal volume.
  • the fuel injection pump with the characterizing features of the main claim has the advantage that a desired distance of the pre-injection before the main injection can be set sufficiently accurately in wide operating ranges of the internal combustion engine with the help of the adjustable fuel removal volume.
  • the point in time at which the connection between the pump chamber and the fuel extraction chamber is opened determines the amount of the pre-injection, which in turn depends on the geometric variables that are independent of the speed and for sufficient operating ranges of the internal combustion engine speed can be adjusted.
  • the fuel injection pump according to the invention can also be implemented on a radial piston pump without significant effort.
  • FIG. 1 shows the first exemplary embodiment in longitudinal section
  • FIG. 2 shows a partial section through the injection pump according to FIG. 1 perpendicular to the sectional plane shown there
  • FIG. 3 shows a development of the distributor according to FIG. 1 together with the lateral surfaces surrounding it
  • FIG. 4 shows part of the cam elevation curve of the cam drive 1 with an assigned injection quantity curve over the angle of rotation
  • FIG. 5 shows a partial development of the distributor and the peripheral surface surrounding it from a further development of the exemplary embodiment according to FIG. 1
  • FIG. 6 shows a second exemplary embodiment in use with an in-line or reciprocating piston injection pump
  • FIG. 7 a third embodiment modification to the embodiment of Figures 1 and 2.
  • a distributor 3 is mounted in a bore 2 and is driven at a pump speed by a drive (not shown further here).
  • the distributor can be coupled at its end to a cam ring carrier 7 via a pin 5 guided through a longitudinal groove 4 provided there, which is approximately cup-shaped and carries a cam ring 8 with a radially inwardly directed cam track 9 on its upper edge. In this way, the cam track and distributor are moved synchronously with one another, the distributor being displaceable in the longitudinal direction by a drive (not shown further here).
  • the distributor has an annular groove 11 on its outer surface, which is in constant connection with one or more pump piston guide bores 12 radially extending from the bore 2, in which pump pistons 14 are arranged, the end face of which has a working space 15 to the side of the annular groove 11 include.
  • Roller plungers 17, which are in contact with the cam track 9 via rollers 18, are guided coaxially with the pump pistons in an adjacent bore 16 with a larger diameter than that of the guide bore 12. Through relative movement of the same, the pistons are set in a reciprocating, pumping and sucking movement.
  • a first control groove 20 and a second control groove 21 branch off from the annular groove 11, which are worked into the surface of the distributor and initially move away from one another in the manner of a V, starting from the annular groove.
  • the second control groove 21 is longer and merges into an axially parallel part 22, which finally opens into a rectangular control surface 23.
  • In the area of the control surface there are outlets of injection lines 25 into the bore 2 distributed on the circumference of the distributor within a radial plane, the injection lines being arranged in accordance with the number and distribution of the combustion chambers to be supplied of the associated internal combustion engine.
  • a plurality of control openings 27 are provided in the lateral surface of the bore 2 in a radial plane, which are connected via lines 28 to a fuel storage space 30.
  • This is supplied in a known manner by a fuel feed pump, not shown here, with fuel which is kept at a relatively low pressure level.
  • the distribution of the control openings 27, which are distributed around the circumference in accordance with the number of fuel injection lines to be supplied, can be seen in the processing according to FIG. 3. They have an approximately trapezoidal cross-section such that the side flanks are opened or closed across the entire width by the first control groove 20 or second control groove 21, each running at the same angle. As can be seen from the processing in FIG.
  • filling channels 34 with a rectangular inlet cross section 33 on the lateral surface of the bore 2 are also provided in the same number and distribution as the control openings 27 in a second radial plane in the region of the axially parallel part 22 of the second control groove 21 such that the inlet cross-section 33 is closed at the same time as the control opening 27 is closed after passing through the second control groove.
  • the fill channels are also connected to the fuel reservoir 30.
  • the distributor 3 has an end part 35 protruding from the bore 2, on which an annular slide 36 is placed, from the inner bore 37 of which a channel 38 radially leads away, which leads into a cylinder 40 incorporated in an extension 39 of the annular slide.
  • a piston 41 is slidably arranged as a movable wall, which is loaded on its rear side by a return spring 42 and on its front side includes a fuel removal space 43 which is connected to the channel 38.
  • the working path of the piston 41 can be limited by an adjustable pin 45, which is used as an adjustable stop coaxially with the return spring 42.
  • the distributor In the area of the ring slide, the axial position of which can be fixed, the distributor has relief openings in the form of longitudinal grooves 46. the axially parallel according to the development of Figure 3. These longitudinal grooves are also arranged according to the number and distribution of the injection lines 25 on the circumference of the distributor and are connected to one another via radial bores 49, which in turn are connected to the control surface 23 or to the annular groove 11 or the pump working chamber 15 via a pressure channel 50 in the distributor.
  • the injection pump shown in this example is a pump for supplying a six-cylinder internal combustion engine with six injection lines 25.
  • the control surface 23 is in register with one of the injection lines 25, into which fuel is subsequently conveyed.
  • the just effective longitudinal groove 46 connected to the control surface 23 has not yet overlapped with the channel 38 branching off from the inner bore 37.
  • a pre-injection according to FIG. 4 is initially carried out over the area ⁇ , which the distributor must rotate further in order to bring the longitudinal groove 46 into overlap with the channel 38 the cam track rolls off. Apply on the cam track, the stretches have been drawn out for which the pre-injection VS and the main injection HS take place. The injection quantities are plotted against the cam angle under the cam elevation curve. As soon as the longitudinal groove 46 comes into overlap with the channel 38, the pressure in the work space is reduced, fuel flowing into the removal space 43, which subsequently receives the fuel delivered by the pump pistons.
  • the trailing boundary edge of the second control grooves 21 inclined in the direction of rotation can be referred to as the first control edges determining the start of spraying
  • the leading boundary edges of the first control grooves 20 inclined in the opposite direction of rotation can be referred to as the second control edges 52 determining the end of the spray .
  • the distance between the first control edge 51 and the second control edge 52 in the region of the radial plane of the control openings 27 thus determines the injection quantities which, due to the inclined arrangement of the control grooves, can be changed by axially displacing the distributor.
  • the angular distance between the pre-injection VS and HS is influenced by the swallowing volume of the fuel removal space 43, which can be adjusted by adjusting the pin 45.
  • the amount of the pre-injection is, as already mentioned, determined by the angle of rotation ⁇ , which, according to the configuration according to FIG.
  • the relief openings or longitudinal grooves 46 are arranged obliquely to the axis of the distributor, the preferably rectangular configuration of the connecting cross section of the channel 38 being adapted to this oblique position with its lateral orientation.
  • FIG. 2 Another embodiment variant is shown in Figure 2, where the ring slide 36 is rotatable with axial fixation by means of a z. B. electrically controlled actuator 54.
  • the point can be varied at which the relief opening 46 connects the pump work space with the fuel removal space. Additional influences on the pre-injection quantity are possible here as a function of further parameters, regardless of the above-mentioned mode of operation.
  • the relief openings used in a radial piston pump can also be designed as inclined longitudinal grooves 46. Instead of a rotary drive, a stroke drive or an axial displacement of the ring slide is also possible, in which case the longitudinal grooves 46 must be inclined in order to effect the adjustment of the pre-injection quantity.
  • This version can be implemented in reciprocating injection pumps. Which is ultimately also applicable to in-line pumps.
  • FIG. 6 An application of the exemplary embodiment to a series pump or a piston injection pump is shown in FIG. 6.
  • a series injection pump only one pump piston 81 is shown, which is set in a generally known manner by a cam of a cam drive shaft into a reciprocating pumping movement.
  • the pump piston encloses a pump working space 88 in a pump cylinder 82.
  • An injection line leads from the latter via a pressure valve to an injection valve assigned to one of the cylinders of the internal combustion engine.
  • a filling and relief line 85 which is connected to a fuel supply pump, opens into the pump cylinder 82.
  • this filling and relief line is controlled by the end face 86 of the pump piston, which delimits the pump working space 88, or by a control edge on this end face, such that during the suction stroke of the pump piston the working space via the filling and relief line 85 at the bottom dead center at the latest , which is now open, is filled with fuel.
  • the effective delivery stroke of the pump piston begins when this line is closed.
  • the pump piston has, in a known manner, an annular groove 83, the boundary edge of which on the pump working space is designed as an oblique control edge 84.
  • the annular groove 83 is connected to the pump working space 88 via a radial bore 90 extending from an axial bore 89 in the pump piston.
  • the pump piston effectively delivers fuel under high pressure into the injection line until the oblique control edge 84 opens the filling and relief line 85 again, so that the pump working space is relieved via the axial bore 89 and the radial bore 90 to the filling and relief line 85 can take place. This stops the high-pressure delivery and ends the injection.
  • the pump piston has a generally known turning device (not shown further here), with which the assignment of the control edge 84 to the mouth of the filling and relief line 85 can be varied and the effective delivery stroke or the fuel injection quantity can be controlled.
  • a part of the pump piston protrudes into a space 91 inside the fuel injection pump.
  • the pump piston carries a ring slide 92 arranged on it in the same way as the ring slide 36 according to the exemplary embodiment according to FIGS. 1 and 2.
  • a channel 95 which corresponds to the channel 38 in FIG. 3, branches off from the inner bore 93 through which the pump piston is tightly guided .
  • This opens into a fuel removal space 96, which is enclosed in a cylinder 97 by a piston 98 which can be moved there tightly.
  • the piston in turn is loaded on its rear side by a return spring 99 and can move against the force of this spring by an amount ⁇ up to an adjustable stop 100.
  • the pump piston In the area of the inner bore 93, the pump piston has an oblique groove 101, in which the axial bore 89 starting from the end face 86 ends.
  • the ring slide is adjustable in the same way as in the exemplary embodiment according to FIGS. 1 and 2 by an adjusting device and can either be axially displaced, rotated or adjusted in both directions, depending on the configuration of the adjusting device and the parameters to be taken into account.
  • the inclined position of the groove 101 allows, for example, a pure rotation of the ring slide 92, so that a larger or smaller pre-injection stroke a becomes effective by the rotation of the ring slide and / or the rotation of the pump piston according to its load position, until the connection between the channel 95 and the ring groove 101 is manufactured.
  • a load-dependent influence on the injection process can be exerted.
  • this can also be compensated for in a targeted manner by rotating the ring slide accordingly. Additional influences can be made via an axial adjustment of the ring slide.
  • the corresponding stop can be designed as a bolt 103 which plunges coaxially into the cylinder 142 and its immersion depth through a effectrically controlled actuator 104 is controlled. In this way, the amount ⁇ or the distance of the pre-injection from the main injection can be varied during ongoing operation.

Description

Stand der TechnickState of the art

Die Erfindung geht von einer Kraftstoffeinspritzpumpe nach der Gattung des Hauptanspruchs aus. Eine durch die DE-C-18 07 554 bekannte Kraftstoffeinspritzpumpe ist als Hubkolbenverteilerpumpe ausgebildet mit einem im Pumpenkolben verlaufenden, vom Pumpenarbeitsraum abzweigenden Entlastungskanal, der einen seitlichen Austritt am Pumpenkolben hat und ab einer bestimmten Hubstellung desselben beim jeweiligen Pumpenförderhub mit einer Entlastungsleitung verbunden wird, die über eine variable und über eine feste Drossel mit einem Entlastungsvolumen konstantem Inhalts verbunden ist. Die Aufnahmefähigkeit dieses Volumens wird bei der bekannten Kraftstoffeinspritzpumpe einmal durch die variable Drossel, die lastabhängig verstellbar ist und zum anderen durch die drehzahlabhängig wirkende feste Drossel bestimmt. Mit dieser Einrichtung soll nur im niedrigen Drehzahl- und Lastbereich eine Verbindung zwischen dem Pumpenarbeitsraum und dem Kraftstoffentnahmeraum herstellbar sein und die Einspritzmenge pro Drehwinkel bzw. Zeit bei Einspritzbeginn insbesondere bei niedrigem Drehzahl- und Lastbereich reduziert werden. Die bekannte Einrichtung läßt jedoch keinen universellen Einsatz zu und es kann insbesondere auch nicht über weite Betriebsbereiche der Brennkraftmaschine die Menge einer Voreinspritzung vor der eigentlichen Haupteinspritzung und der zeitliche Abstand zwischen Voreinspritzung und Haupteinspritzung festgelegt werden.The invention is based on a fuel injection pump according to the preamble of the main claim. A fuel injection pump known from DE-C-18 07 554 is designed as a reciprocating piston distributor pump with a relief channel running in the pump piston and branching off from the pump work space, which has a lateral outlet on the pump piston and is connected to a relief line from a certain stroke position of the respective pump delivery stroke is connected to a discharge volume of constant content via a variable and a fixed throttle. In the known fuel injection pump, the capacity of this volume is determined on the one hand by the variable throttle, which is adjustable depending on the load, and on the other hand by the fixed throttle, which acts as a function of the speed. With this device, it should only be possible to establish a connection between the pump work space and the fuel removal space in the low speed and load range and the injection quantity per angle of rotation or time at the start of injection should be reduced, in particular at a low speed and load range. However, the known device does not permit universal use and, in particular, the amount of a pre-injection before the actual main injection and the time interval between the pre-injection and the main injection cannot be determined over wide operating ranges of the internal combustion engine.

Durch die FR-A-20 93 250 ist ferner eine Verteilerkraftstoffeinspritzpumpe bekannt, bei der ähnlich wie bei der eingangs genannten Verteilerkraftstoffeinspritzpumpe ein Teil des von dem Pumpenkolben geförderten Kraftstoffs in einen Kraftstoffentnahmeraum abgegeben werden kann, der bei jedem Kraftstoffeinspritzvorgang der Verteilerkraftstoffeinspritzpumpe erneut angesteuert wird. Diese Ansteuerung erfolgt jedoch bei einem festgelegten Hub des Pumpenkolbens bzw. bei einer festgelegten Drehstellung eines Verteilers der Verteilerkraftstoffeinspritzpumpe, wobei der Entnahmeraum aus einer Kombination zwischen einem Festvolumenspeicher und einem diesem Speicher vorgeschalteten Ausweichkolben besteht. Mit zunehmender Drehzahl verringert sich der von diesem zurückgelegte Weg, der jeweils dem wirksamen Aufnahmevolumen des Speichers entspricht unter Einwirkung einer die Rücklaufbewegung des Kolbens hemmenden Drossel. Durch diese Einrichtung wird über die Dauer der Gesamteinspritzzeit eine Reduzierung der Einspritzrate und damit auch der Einspritzmenge erzielt. Die Einrichtung ist nur innerhalb eines einzigen Drehzahlbereiches wirksam.From FR-A-20 93 250 a distributor fuel injection pump is also known, in which, similarly to the distributor fuel injection pump mentioned at the beginning, part of the fuel delivered by the pump piston can be dispensed into a fuel removal space which is activated again with each fuel injection process of the distributor fuel injection pump. However, this activation takes place with a fixed stroke of the pump piston or with a fixed rotational position of a distributor of the distributor fuel injection pump, the removal space consisting of a combination between a fixed volume accumulator and an escape piston connected upstream of this accumulator. With increasing speed, the distance covered by this decreases, which corresponds in each case to the effective receiving volume of the accumulator under the action of a throttle which restricts the return movement of the piston. Through this device, a reduction in the injection rate and thus also the injection quantity is achieved over the duration of the total injection time. The device is only effective within a single speed range.

Es ist weiterhin eine Kraftstofffeinspritzpumpe durch die FR-C-1 495 537 bekannt, bei der der Pumpenarbeitsraum über eine Drossel ständig mit einem Kraftstoffentnahmeraum verbunden ist. Dieser wird von einem Ausweichkolben begrenzt, dessen Ausweichbewegung durch eine Zusatzeinrichtung in einem bestimmten Betriebsbereich der Brennkraftmaschine blockiert werden kann derart, daß die Entnahmefunktion des Kraftstoffentnahmeraums aufgehoben wird. Bei dieser bekannten Kraftstoffeinspritzpumpe wird wie auch bei obengenanntem Stand der Technik die Kraftstoffeinspritzrate über einen Teil des Förderhubs des Pumpenkolbens reduziert.A fuel injection pump is also known from FR-C-1 495 537, in which the pump work space is continuously connected to a fuel extraction space via a throttle. This is limited by an evasive piston, the evasive movement of which can be blocked by an additional device in a certain operating range of the internal combustion engine in such a way that the removal function of the fuel removal space is canceled. In this known fuel injection pump, as in the aforementioned prior art, the fuel injection rate is reduced over part of the delivery stroke of the pump piston.

Nachausgestaltungen mit zusätzlichen Steuerquerschnitten am Ausweichkolben erzeugen auch eine Unterbrechung der Kraftstoffeinspritzung. Diese ist durch die konstruktive Anordnung der Steuerquerschnitte grundsätzlich festgelegt und kann nicht separat beeinflußt werden. In gleicher Weise ist eine Beeinflussung auch nur durch das Blockieren des Ausweichkolbens möglich so daß im übrigen Betriebsbereich die Kraftstoffentnahmeeinrichtung in durchgehend gleicher Weise wirkt, wie das auch bei der bereits eingangs genannten Kraftstoffeinspritzpumpe der Fall ist.Refinements with additional control cross sections on the alternative piston also produce an interruption in fuel injection. This is basically determined by the structural arrangement of the control cross sections and cannot be influenced separately. In the same way, influencing is also possible only by blocking the evasive piston, so that in the remaining operating range the fuel extraction device acts in the same way throughout, as is also the case with the fuel injection pump already mentioned at the beginning.

Eine Kraftstoffeinspritzpumpe der gattungsgemäßen Art ist durch die DE-C-585 014 bekannt. Dort führt die bewegliche Wand bei jedem Ansteuervorgang der Entlastungsöffnung ihren Hub bis zum einstellbaren Anschlag aus, wobei eine bestimmte festgelegte Kraftstoffmenge der vom Pumpenkolben geförderten Kraftstoffmenge entnommen wird. Abweichend von dem eingangs diskutierten Stand der Technik ist bei dieser Kraftstoffeinspritzpumpe der Zeitpunkt der Unterbrechung der Kraftstoffeinspritzung während des Einspritzverlaufes in Abhängigkeit der Haupteinspritzmenge veränderlich. Bei gleichbleibendem Förderbeginn ergibt sich somit eine mit abnehmender Last verringernde Kraftstoffvoreinspritzmenge. Mit einer solchen Kraftstoffeinspritzpumpe läßt sich daher nur in einer ganz bestimmten Gesetzmäßigkeit die Menge der Voreinspritzung steuern. Weiterhin liegt durch das Entnahmevolumen der Abstand zwischen Voreinspritzung und Haupteinspritzung fest.A fuel injection pump of the generic type is known from DE-C-585 014. There, the movable wall executes its stroke up to the adjustable stop with each actuation process of the relief opening, a certain fixed quantity of fuel being taken from the quantity of fuel delivered by the pump piston. In a departure from the prior art discussed at the outset, in this fuel injection pump the point in time at which the fuel injection is interrupted during the course of the injection can be varied as a function of the main injection quantity. If the start of delivery remains the same, the fuel pre-injection quantity decreases as the load decreases. With such a fuel injection pump, the amount of pre-injection can therefore only be controlled in a very specific law. Furthermore, the distance between the pre-injection and the main injection is determined by the withdrawal volume.

Vorteile der ErfindungAdvantages of the invention

Die Kraftstoffeinspritzpumpe mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, daß mit Hilfe des einstellbaren Kraftstoffentnahmevolumens ein gewünschter Abstand der Voreinspritzung vor der Haupteinspritzung in weiten Betriebsbereichen der Brennkraftmaschine ausreichend genau eingestellt werden kann. Der Zeitpunkt der Aufsteuerung der Verbindung zwischen Pumpenraum und Kraftstoffentnahmeraum bestimmt dabei die Menge der Voreinspritzung, die wiederum von drehzahlunabhängigen geometrischen Größen abhängt und für weite Betriebsbereiche der Brennkraftmaschine mit hinreichender Genauigkeit eingestellt werden kann.The fuel injection pump with the characterizing features of the main claim has the advantage that a desired distance of the pre-injection before the main injection can be set sufficiently accurately in wide operating ranges of the internal combustion engine with the help of the adjustable fuel removal volume. The point in time at which the connection between the pump chamber and the fuel extraction chamber is opened determines the amount of the pre-injection, which in turn depends on the geometric variables that are independent of the speed and for sufficient operating ranges of the internal combustion engine speed can be adjusted.

Dabei bietet sich die Möglichkeit, die Menge der Voreinspritzung auch in Abhängigkeit von Betriebsparametern exakt zu steuern und auch während des Betriebs der Kraftstoffeinspritzpumpe zu verändern. In vorteilhafter Weise ist die erfindungsgemäße Kraftstoffeinspritzpumpe auch an einer Radialkolbenpumpe ohne wesentlichen Aufwand verwirklichbar.This offers the possibility of precisely controlling the amount of pilot injection as a function of operating parameters and also of changing it during operation of the fuel injection pump. Advantageously, the fuel injection pump according to the invention can also be implemented on a radial piston pump without significant effort.

In den übrigen Unteränsprüchen sind vorteilhafte Ausgestaltungen der Erfindung angegeben, sie werden mit ihren Vorteilen in der nachfolgenden Beschreibung näher erläutert.Advantageous refinements of the invention are specified in the remaining subclaims, and their advantages are explained in more detail in the description below.

Zeichnungdrawing

Drei Ausführungsbeispiele des Gegenstands der Erfindung am Beispiel einer Radialkolbenpumpe sind in der Zeichnung vereinfacht dargestellt und werden im folgenden näher beschrieben. Es zeigen Figur 1 das erste Ausführungsbeispiel im Längsschnitt, Figur 2 einen Teilschnitt durch die Einspritzpumpe nach Figur 1 senkrecht zur dort wiedergegebenen Schnittebene, Figur 3 eine Abwicklung des Verteilers gemäß Figur 1 zusammen mit den ihn umgebenden Mantelflächen, Figur 4 ein Teil der Nockenerhebungskurve des Nockenantriebs der Pumpenkolben des Ausführungsbeispiels nach Figur 1 mit zugeordnetem Einspritzmengenverlauf über den Drehwinkel, Figur 5 eine Teilabwicklung von Verteiler und ihn umgebender Mantelfläche von einer Weiterbildung des Ausführungsbeispiels nach Figur 1, Figur 6 ein zweites Ausführungsbeispiel in Anwendung bei einer Reihen- bzw. Hubkolbeneinspritzpumpe und Figur 7 ein drittes Ausführungsbeispiel Abwandlung zum Ausführungsbeispiel nach Figuren 1 und 2.Three exemplary embodiments of the object of the invention using the example of a radial piston pump are shown in simplified form in the drawing and are described in more detail below. 1 shows the first exemplary embodiment in longitudinal section, FIG. 2 shows a partial section through the injection pump according to FIG. 1 perpendicular to the sectional plane shown there, FIG. 3 shows a development of the distributor according to FIG. 1 together with the lateral surfaces surrounding it, FIG. 4 shows part of the cam elevation curve of the cam drive 1 with an assigned injection quantity curve over the angle of rotation, FIG. 5 shows a partial development of the distributor and the peripheral surface surrounding it from a further development of the exemplary embodiment according to FIG. 1, FIG. 6 shows a second exemplary embodiment in use with an in-line or reciprocating piston injection pump and FIG. 7 a third embodiment modification to the embodiment of Figures 1 and 2.

Beschreibungdescription

In einem Gehäuse 1 einer Radialkolbenverteilereinspritzpumpe ist in einer Bohrung 2 ein Verteiler 3 gelagert, der durch einen hier nicht weiter gezeigten Antrieb mit Pumpendrehzahl angetrieben ist. Dabei kann der Verteiler an seinem Ende über einen durch eine dort vorgesehene Längsnut 4 geführten Bolzen 5 mit einem Nockenringträger 7 gekoppelt sein, der etwa tassenförmig ausgebildet ist und an seinem oberen Rand einen Nockenring 8 mit radial einwärts gerichteter Nockenbahn 9 trägt. Auf diese Weise werden Nockenbahn und Verteiler synchron zueinander bewegt, wobei durch einen hier nicht weiter dargestellten Antrieb der Verteiler in Längsrichtung verschiebbar ist.In a housing 1 of a radial piston distributor injection pump, a distributor 3 is mounted in a bore 2 and is driven at a pump speed by a drive (not shown further here). The distributor can be coupled at its end to a cam ring carrier 7 via a pin 5 guided through a longitudinal groove 4 provided there, which is approximately cup-shaped and carries a cam ring 8 with a radially inwardly directed cam track 9 on its upper edge. In this way, the cam track and distributor are moved synchronously with one another, the distributor being displaceable in the longitudinal direction by a drive (not shown further here).

Der Verteiler weist auf seiner Mantelfläche eine Ringnut 11 auf, die in ständiger Verbindung mit einer oder mehreren radial von der Bohrung 2 abgehenden Pumpenkolben-Führungsbohrungen 12 ist, in denen Pumpenkolben 14 angeordnet sind, die mit ihrer Stirnseite einen Arbeitsraum 15 zur Seite der Ringnut 11 hin einschließen. Koaxial zu den Pumpenkolben sind in einer angrenzenden Bohrung 16 mit größerem Durchmesser als dem der Führungsbohrung 12 Rollenstößel 17 geführt, die über Rollen 18 im Kontakt mit der Nockenbahn 9 sind. Durch Relativbewegung derselben werden die Kolben in eine hin- und hergehende, pumpende und saugende Bewegung versetzt.The distributor has an annular groove 11 on its outer surface, which is in constant connection with one or more pump piston guide bores 12 radially extending from the bore 2, in which pump pistons 14 are arranged, the end face of which has a working space 15 to the side of the annular groove 11 include. Roller plungers 17, which are in contact with the cam track 9 via rollers 18, are guided coaxially with the pump pistons in an adjacent bore 16 with a larger diameter than that of the guide bore 12. Through relative movement of the same, the pistons are set in a reciprocating, pumping and sucking movement.

Von der Ringnut 11 zweigen eine erste Steuernut 20 und eine zweite Steuernut 21 ab, die in die Oberfläche des Verteilers eingearbeitet sind und sich zunächst ausgehend von der Ringnut in der Art eines V voneinander entfernen. Die zweite Steuernut 21 ist dabei länger ausgebildet und geht in einen achsparallelen Teil 22 über, der schließlich in eine rechteckige Steuerfläche 23 mündet. Im Bereich der Steuerfläche befinden sich am Umfang des Verteilers verteilt Einmündungen von Einspritzleitungen 25 in die Bohrung 2 innerhalb einer radialen Ebene, wobei die Einspritzleitungen entsprechend der Zahl und Verteilung der zu versorgenden Brennräume der zugehörenden Brennkraftmaschine angeordnet sind.A first control groove 20 and a second control groove 21 branch off from the annular groove 11, which are worked into the surface of the distributor and initially move away from one another in the manner of a V, starting from the annular groove. The second control groove 21 is longer and merges into an axially parallel part 22, which finally opens into a rectangular control surface 23. In the area of the control surface, there are outlets of injection lines 25 into the bore 2 distributed on the circumference of the distributor within a radial plane, the injection lines being arranged in accordance with the number and distribution of the combustion chambers to be supplied of the associated internal combustion engine.

Im Arbeitsbereich der ersten, kürzeren Steuernut 20 sind in der Mantelfläche der Bohrung 2 in einer Radialebene mehrere Steueröffnungen 27 vorgesehen, die über Leitungen 28 mit einem Kraftstoffvorratsraum 30 verbunden sind. Dieser wird von einer hier nicht weiter dargestellten Kraftstoffvorförderpumpe in bekannter Weise mit Kraftstoff versorgt, der auf einem relativ niedrigen Druckniveau gehalten wird. Die Verteilung der Steueroffnungen 27, die entsprechend der Zahl der zu versorgenden Kraftstoffeinspritzleitungen am Umfang verteilt angeordnet sind, ist der Abwicklung gemäß Figur 3 zu entnehmen. Sie haben etwa trapezförmigen Querschnitt derart, daß die Seitenflanken über die gesamte Breite durch die jeweils im gleichen Winkel verlaufende erste Steuernut 20 bzw. zweite Steuernut 21 auf- bzw. zugesteuert werdend. Wie der Abwicklung Figur 3 zu entnehmen ist, sind ferner in einer zweiten Radialebene im Bereich des achsparallelen Teils 22 der zweiten Steuernut 21 Füllkanäle 34 mit rechteckigem Eintrittsquerschnitt 33 an der Mantelfläche der Bohrung 2 vorgesehen in gleicher Zahl und Verteilung wie die Steueröffnungen 27, und zwar derart, daß der Eintrittsquerschnitt 33 jeweils zugleich mit dem Schließen der Steueröffnung 27 nach Passieren der zweiten Steuernut verschlossen wird. Die Füllkanäle sind gleichfalls mit dem Kraftstoffvorratsraum 30 verbunden.In the working area of the first, shorter control groove 20, a plurality of control openings 27 are provided in the lateral surface of the bore 2 in a radial plane, which are connected via lines 28 to a fuel storage space 30. This is supplied in a known manner by a fuel feed pump, not shown here, with fuel which is kept at a relatively low pressure level. The distribution of the control openings 27, which are distributed around the circumference in accordance with the number of fuel injection lines to be supplied, can be seen in the processing according to FIG. 3. They have an approximately trapezoidal cross-section such that the side flanks are opened or closed across the entire width by the first control groove 20 or second control groove 21, each running at the same angle. As can be seen from the processing in FIG. 3, filling channels 34 with a rectangular inlet cross section 33 on the lateral surface of the bore 2 are also provided in the same number and distribution as the control openings 27 in a second radial plane in the region of the axially parallel part 22 of the second control groove 21 such that the inlet cross-section 33 is closed at the same time as the control opening 27 is closed after passing through the second control groove. The fill channels are also connected to the fuel reservoir 30.

Der Verteiler 3 weist ein aus der Bohrung 2 herausragendes Endteil 35 auf, auf dem ein Ringschieber 36 aufgesetzt ist, von dessen Innenbohrung 37 radial ein Kanal 38 abführt, der in einen in einem Ansatz 39 des Ringschiebers eingearbeiteten Zylinder 40 führt. In diesem ist ein Kolben 41 als bewegliche Wand verschiebbar angeordnet, der auf seiner Rückseite durch eine Rückstellfeder 42 belastet ist und auf seiner Vorderseite einen Kraftstoffentnahmeraum 43 einschließt, der mit dem Kanal 38 verbunden ist. Der Arbeitsweg des Kolbens 41 ist durch einen verstellbaren Zapfen 45, der als verstellbarer Anschlag koaxial zur Rückstellfeder 42 eingesetzt ist, begrenzbar.The distributor 3 has an end part 35 protruding from the bore 2, on which an annular slide 36 is placed, from the inner bore 37 of which a channel 38 radially leads away, which leads into a cylinder 40 incorporated in an extension 39 of the annular slide. In this, a piston 41 is slidably arranged as a movable wall, which is loaded on its rear side by a return spring 42 and on its front side includes a fuel removal space 43 which is connected to the channel 38. The working path of the piston 41 can be limited by an adjustable pin 45, which is used as an adjustable stop coaxially with the return spring 42.

Im Bereich des Ringschiebers, dessen axiale Stellung fixierbar ist, weist der Verteiler Entlastungsöffnungen in Form von Längsnuten 46 auf, die achsparallel gemäß Abwicklung nach Figur 3 verlaufen. Diese Längsnuten sind ebenfalls entsprechend der Zahl und Verteilung der Einspritzleitungen 25 am Umfang des Verteilers angeordnet und sind untereinander über Radialbohrungen 49 verbunden, die wiederum über einen Druckkanal 50 im Verteiler mit der Steuerfläche 23 bzw. mit der Ringnut 11 oder dem Pumpenarbeitsraum 15 verbunden sind.In the area of the ring slide, the axial position of which can be fixed, the distributor has relief openings in the form of longitudinal grooves 46. the axially parallel according to the development of Figure 3. These longitudinal grooves are also arranged according to the number and distribution of the injection lines 25 on the circumference of the distributor and are connected to one another via radial bores 49, which in turn are connected to the control surface 23 or to the annular groove 11 or the pump working chamber 15 via a pressure channel 50 in the distributor.

.Anhand der Abwicklung von Figur 3 soll die Arbeitsweise der Kraftstoffeinspritzpumpe nach Figur 1 beschrieben werden, wobei zunächst davon ausgegangen wird, daß der Ringschieber 36 in seiner Drehstellung fixiert ist. Wie man aus der Abwicklung erkennt, handelt es sich bei der bei diesem Beispiel gezeigten Einspritzpumpe um eine Pumpe zur Versorgung einer Sechszylinderbrennkraftmaschine mit sechs Einspritzleitungen 25. Zur Verbesserung des Füllungswechsels der Pumpenarbeitsräume 15 sind hier zwei erste Steuernuten 20, 20' und zwei zweite Steuernuten 21, 21' vorgesehen, wobei jedoch nur eine der zweiten Steuernuten die Steuerfläche 23 aufweist. In der gezeigten Darstellung ist soeben die Füllung der Pumpenarbeitsräume abgeschlossen worden und es beginnt der wirksame Fördertakt der Pumpenkolben. Dazu befindet sich die Steuerfläche 23 in Überdeckung mit einer der Einspritzleitungen 25, in die in der Folge Kraftstoff gefördert wird. Die mit der Steuerfläche 23 verbundene, gerade wirksame Längsnut 46 ist dabei noch nicht in Überdeckung mit dem von der Innenbohrung 37 abzweigenden Kanal 38 gelangt. Über den Bereich α, den sich der Verteiler weiter drehen muß, um die Längsnut 46 in Überdeckung mit den Kanal 38 zu bringen, erfolgt zunächst eine Voreinspritzung gemäß Figur 4. Dort ist der Nockenanstieg eines Nockens der Nockenbahn dargestellt mit einem Rollenstößel 17, der auf der Nockenbahn abrollt. Auf der Nockenbahn auftragen sind ausgezogen die Strecken, bei denen die Voreinspritzung VS und die Haupteinspritzung HS erfolgt. Unter der Nockenerhebungskurve sind die Einspritzmengen über den Nockenwinkel aufgetragen. Sobald die Längsnut 46 in Überdeckung mit dem Kanal 38 kommt, wird der Druck im Arbeitsraum abgebaut, wobei Kraftstoff in den Entnahmeraum 43 überströmt, der in der Folge den von den Pumpenkolben geförderten Kraftstoff aufnimmt. Sobald die Aufnahmekapazität des Entnahmeraums 43 erschöpft ist, beginnt danach wieder ein Druckanstieg im Pumpenarbeitsraum und damit mit dem weiterhin geförderten Kraftstoff die Haupteinspritzung, solange, bis die ersten Steuernuten 20 in Überdeckung mit den Steueröffnungen 27 gelangen. In diesem Punkt wird die Einspritzung unterbrochen und etwa noch restlich geförderter Kraftstoff in den Kraftstoffvorratsraum 30 übergeschoben. In diesem Punkt erfolgt dann auch, insbesondere dann, wenn in der Folge der achsparallele Teil 22 der zweiten Steuernut 21 in Überdeckung mit dem Eintrittsquerschnitt 33 gelangt, daß sich das Kraftstoffvolumen im Entnahmeraum 43 entspannt, so daß der Kolben 41 in seine Ausgangslage zurückkehrt. Im Laufe der weiteren Bewegung des Verteilers gelangen auch die ersten Steuernuten 20 in Überdeckung mit den Steueröffnungen 27, so daß ein ausreichend großer Füllquerschnitt während des sich anschließenden Saughubs der Pumpenkolben zur Verfügung steht. Es kann Kraftstoff sowohl über die ersten Steuernuten als auch über die zweiten Steuernuten in den Pumpenarbeitsraum gelangen bei geöffneten Steueröffnungen 27 und Eintrittsquerschnitten 33.3, the mode of operation of the fuel injection pump according to FIG. 1 is to be described, it being initially assumed that the ring slide 36 is fixed in its rotational position. As can be seen from the processing, the injection pump shown in this example is a pump for supplying a six-cylinder internal combustion engine with six injection lines 25. To improve the filling change of the pump work spaces 15, there are two first control grooves 20, 20 'and two second control grooves 21 , 21 'is provided, but only one of the second control grooves has the control surface 23. In the illustration shown, the filling of the pump work spaces has just been completed and the effective delivery cycle of the pump pistons begins. For this purpose, the control surface 23 is in register with one of the injection lines 25, into which fuel is subsequently conveyed. The just effective longitudinal groove 46 connected to the control surface 23 has not yet overlapped with the channel 38 branching off from the inner bore 37. A pre-injection according to FIG. 4 is initially carried out over the area α, which the distributor must rotate further in order to bring the longitudinal groove 46 into overlap with the channel 38 the cam track rolls off. Apply on the cam track, the stretches have been drawn out for which the pre-injection VS and the main injection HS take place. The injection quantities are plotted against the cam angle under the cam elevation curve. As soon as the longitudinal groove 46 comes into overlap with the channel 38, the pressure in the work space is reduced, fuel flowing into the removal space 43, which subsequently receives the fuel delivered by the pump pistons. As soon as the absorption capacity of the removal space 43 is exhausted, a pressure rise in the pump work space begins again and the main injection continues with the fuel that is still being delivered until the first control grooves 20 overlap with the control openings 27. At this point, the injection is interrupted and any fuel that is still being delivered is pushed into the fuel reservoir 30. At this point it also occurs, in particular when the axially parallel part 22 of the second control groove 21 subsequently overlaps the inlet cross section 33 that the fuel volume in the removal space 43 relaxes, so that the piston 41 returns to its initial position. In the course of the further movement of the distributor, the first control grooves 20 also overlap with the control openings 27, so that a sufficiently large filling cross section is available during the subsequent suction stroke of the pump pistons. Fuel can get into the pump work space both via the first control grooves and via the second control grooves when the control openings 27 and inlet cross sections 33 are open.

Man sieht aus dem Vorbeschriebenen, daß die nachlaufende Begrenzungskante der in Drehrichtung geneigten zweiten Steuernuten 21 als die den Spritzbeginn bestimmenden ersten Steuerkanten zu bezeichnen sind, während die vorlaufenden Begrenzungskanten der entgegen Drehrichtung geneigten ersten Steuernuten 20 als die das Spritzende bestimmenden zweiten Steuerkanten 52 zu bezeichnen sind. Der Abstand zwischen erster Steuerkante 51 und zweiter Steuerkante 52 im Bereich der Radialebene der Steueröffnungen 27 bestimmt somit die Einspritzmengen, die wegen der geneigten Anordnungen der Steuernuten durch axiales Verschieben des Verteilers änderbar sind.It can be seen from the above that the trailing boundary edge of the second control grooves 21 inclined in the direction of rotation can be referred to as the first control edges determining the start of spraying, while the leading boundary edges of the first control grooves 20 inclined in the opposite direction of rotation can be referred to as the second control edges 52 determining the end of the spray . The distance between the first control edge 51 and the second control edge 52 in the region of the radial plane of the control openings 27 thus determines the injection quantities which, due to the inclined arrangement of the control grooves, can be changed by axially displacing the distributor.

Der Winkelabstand zwischen Voreinspritzung VS und HS wird beeinflußt durch das Schluckvolumen des Kraftstoffentnahmeraums 43, das durch die Verstellung des Zapfens 45 eingestellt werden kann. Die Menge der Voreinspritzung dagegen wird wie bereits erwähnt durch den Drehwinkel α bestimmt, der gemäß der Ausgestaltung nach Figur 5 noch lastabhängig verändert werden kann. Bei dieser Variante sind die Entlastungsöffnungen bzw. Längsnuten 46 schräg zur Achse des Verteilers angeordnet, wobei die vorzugsweise rechteckige Ausbildung des Verbindungsquerschnitts des Kanals 38 mit seiner Seitenausrichtung dieser Schräglage angepaßt ist. In Figur 5 sind drei verschiedene Axialstellungen des Verteilers dargestellt und man sieht daraus, daß in Abhängigkeit dieser Stellungen sich der Winkel a ändert und somit kann auch die Voreinspritzmenge der jeweiligen Last der Brennkraftmaschine angepaßt werden. Die Voreinspritzung kann dabei proportional zur Haupteinspritzmenge verändert werden oder auch umgekehrt proportional, je nach Neigung der Längsnuten 46.The angular distance between the pre-injection VS and HS is influenced by the swallowing volume of the fuel removal space 43, which can be adjusted by adjusting the pin 45. On the other hand, the amount of the pre-injection is, as already mentioned, determined by the angle of rotation α, which, according to the configuration according to FIG. In this variant, the relief openings or longitudinal grooves 46 are arranged obliquely to the axis of the distributor, the preferably rectangular configuration of the connecting cross section of the channel 38 being adapted to this oblique position with its lateral orientation. In Figure 5, three different axial positions of the distributor are shown and it can be seen that the angle a changes as a function of these positions and thus the pre-injection quantity can also be adapted to the respective load of the internal combustion engine. The pre-injection can be changed in proportion to the main injection quantity or in reverse proportion, depending on the inclination of the longitudinal grooves 46.

Es ist im Vorstehenden am Beispiel einer Radialkolbenpumpe mit verschiebbarem Verteiler eine Ausgestaltung beschrieben worden, bei der Entlastungsöffnungen 46 entsprechend der Zahl und Verteilung der Einspritzleitungen am Verteiler angeordnet sind. In äquivalenter Weise ist natürlich auch die Version möglich, daß der Verteiler nur eine Entlastungsöffnung aufweist, und dafür in der Mantelfläche der Innenbohrung 37 des Ringschiebers 36 solche Entlastungsöffnungen entsprechend der Zahl der zu versorgenden Brennräume der Brennkraftmaschine vorgesehen sind. Diese Entlastungsöffnungen sind dann jeweils mit dem Kraftstoffentnahmeraum 43 in ständiger Verbindung.An embodiment has been described above using the example of a radial piston pump with a displaceable distributor, in which relief openings 46 are arranged on the distributor in accordance with the number and distribution of the injection lines. In an equivalent manner, of course, the version is also possible that the distributor has only one relief opening, and for that purpose such relief openings are provided in the lateral surface of the inner bore 37 of the ring slide 36 corresponding to the number of combustion chambers of the internal combustion engine to be supplied. These relief openings are then in constant communication with the fuel removal space 43.

Das gleiche Prinzip läßt sich auch bei einer Hubkolbeneinspritzpumpe verwirklichen, wobei als Entlastungsöffnungen keine Längsnuten mehr notwendig sind bzw. auch nicht brauchbar sind, da hier durch die Hubbewegung des Kolbens der Punkt bestimmt wird, bei dem die Verbindung zwischen Pumpenarbeitsraum und Kraftstoffentnahmeraum 43 hergestellt wird.The same principle can be applied to one Realize reciprocating injection pump, wherein no longitudinal grooves are no longer necessary or not usable as relief openings, since here the point at which the connection between the pump work space and the fuel extraction space 43 is established is determined by the stroke movement of the piston.

Eine weitere Ausführungsvariante ist in Figur 2 dargestellt, wo der Ringschieber 36 bei axialer Fixierung verdrehbar ist mittels einer z. B. elektrisch gesteuerten Stelleinrichtung 54. Mit dieser Einrichtung läßt sich der Punkt variieren, bei dem die Entlastungsöffnung 46 den Pumpenarbeitsraum mit dem Kraftstoffentnahmeraum verbindet. Es sind hier zusätzliche Beeinflussungen der Voreinspritzmenge in Abhängigkeit von weiteren Parametern unabhängig von der vorgenannten Arbeitsweise möglich. Die bei einer Radialkolbenpumpe verwendeten Entlastungsöffnungen können dabei auch als geneigte Längsnuten 46 ausgeführt werden. Statt eines Drehantriebs ist auch ein Hubantrieb bzw. eine Axialverschiebung des Ringschiebers möglich, wobei in diesem Fall die Längsnuten 46 geneigt sein müssen, um die Verstellung der Voreinspritzmenge zu bewirken. Diese Ausführung läßt sich bei Hubkolbeneinspritzpumpen verwirklichen. Was auch letztlich bei Reihenpumpen anwendbar ist.Another embodiment variant is shown in Figure 2, where the ring slide 36 is rotatable with axial fixation by means of a z. B. electrically controlled actuator 54. With this device, the point can be varied at which the relief opening 46 connects the pump work space with the fuel removal space. Additional influences on the pre-injection quantity are possible here as a function of further parameters, regardless of the above-mentioned mode of operation. The relief openings used in a radial piston pump can also be designed as inclined longitudinal grooves 46. Instead of a rotary drive, a stroke drive or an axial displacement of the ring slide is also possible, in which case the longitudinal grooves 46 must be inclined in order to effect the adjustment of the pre-injection quantity. This version can be implemented in reciprocating injection pumps. Which is ultimately also applicable to in-line pumps.

Eine Anwendung des Ausführungsbeispiels bei einer Reihenpumpe bzw. bei einer Kolbeneinspritzpumpe zeigt Figur 6. Dort ist bei einer Reiheneinspritzpumpe lediglich ein Pumpenkolben 81 gezeigt, der in allgemein bekannter Weise durch einen Nocken einer Nockenantriebswelle in eine hin- und hergehende pumpende Bewegung versetzt wird. Der Pumpenkolben schließt in einem Pumpenzylinder 82 einen Pumpenarbeitsraum 88 ein. Von diesem führt über ein Druckventil eine Einspritzleitung ab zu einem einem der Zylinder der Brennkraftmaschine zugeordneten Einspritzventil. In bekannter Weise mündet in den Pumpenzylinder 82 eine Füll- und Entlastungsleitung 85, die mit einer Kraftstoffversorgungspumpe verbunden is. Die Öffnung dieser Füll- und Entlastungsleitung wird durch die Stirnfläche 86 des Pumpenkolbens, die den Pumpenarbeitsraum 88 begrenzt, oder durch eine Steuerkante an dieser Stirnfläche gesteuert, derart, daß beim Saughub des Pumpenkolbens spätestens im unteren Totpunkt der Arbeitsraum über die Füll- und Entlastungsleitung 85, die nunmehr geöffnet ist, mit Kraftstoff gefüllt wird. Der wirksame Förderhub des Pumpenkolbens beginnt mit Schließen dieser Leitung. Zur Bestimmung des wirksamen Pumpenförderhubs bzw. der einzuspritzenden Kraftstoffmenge weist der Pumpenkolben in bekannter Weise eine Ringnut 83 auf, deren pumpenarbeitsraumseitige Begrenzungskante als schräge Steuerkante 84 ausgebildet ist. Die Ringnut 83 steht über eine von einer Axialbohrung 89 im Pumpenkolben abgehende Radialbohrung 90 mit dem Pumpenarbeitsraum 88 in Verbindung. Nach Beginn des wirksamen Förderhubs bzw. nach Schließen der Füll- und Entlastungsleitung fördert der Pumpenkolben solange wirksam Kraftstoff unter Hochdruck in die Einspritzleitung, bis die schräge Steuerkante 84 die Füll- und Entlastungsleitung 85 wieder öffnet, so daß eine Entlastung des Pumpenarbeitsraumes über die Axialbohrung 89 und die Radialbohrung 90 zur Füll- und Entlastungsleitung 85 hin erfolgen kann. Damit wird die Hochdruckförderung unterbrochen und die Einspritzung beendet. Der Pumpenkolben weist eine hier nicht weiter gezeigte jedoch allgemein bekannte Verdreheinrichtung auf, womit die Zuordnung der Steuerkante 84 zur Mündung der Füll- und Entlastungsleitung 85 variiert werden kann und der wirksame Förderhub bzw. die Kraftstoffeinspritzmenge gesteuert werden kann.An application of the exemplary embodiment to a series pump or a piston injection pump is shown in FIG. 6. In a series injection pump, only one pump piston 81 is shown, which is set in a generally known manner by a cam of a cam drive shaft into a reciprocating pumping movement. The pump piston encloses a pump working space 88 in a pump cylinder 82. An injection line leads from the latter via a pressure valve to an injection valve assigned to one of the cylinders of the internal combustion engine. In a known manner, a filling and relief line 85, which is connected to a fuel supply pump, opens into the pump cylinder 82. The opening of this filling and relief line is controlled by the end face 86 of the pump piston, which delimits the pump working space 88, or by a control edge on this end face, such that during the suction stroke of the pump piston the working space via the filling and relief line 85 at the bottom dead center at the latest , which is now open, is filled with fuel. The effective delivery stroke of the pump piston begins when this line is closed. In order to determine the effective pump delivery stroke or the amount of fuel to be injected, the pump piston has, in a known manner, an annular groove 83, the boundary edge of which on the pump working space is designed as an oblique control edge 84. The annular groove 83 is connected to the pump working space 88 via a radial bore 90 extending from an axial bore 89 in the pump piston. After the start of the effective delivery stroke or after the filling and relief line has been closed, the pump piston effectively delivers fuel under high pressure into the injection line until the oblique control edge 84 opens the filling and relief line 85 again, so that the pump working space is relieved via the axial bore 89 and the radial bore 90 to the filling and relief line 85 can take place. This stops the high-pressure delivery and ends the injection. The pump piston has a generally known turning device (not shown further here), with which the assignment of the control edge 84 to the mouth of the filling and relief line 85 can be varied and the effective delivery stroke or the fuel injection quantity can be controlled.

Ein Teil des Pumpenkolben ragt in einen Raum 91 im Innern der Kraftstoffeinspritzpumpe. Dort führt der Pumpenkolben einen auf ihm angeordneten Ringschieber 92 gleicherart wie der Ringschieber 36 gemäß Ausführungsbeispiel nach Figur 1 bzw. 2. Von der Innenbohrung 93, durch die der Pumpenkolben dicht geführt ist, zweigt ein Kanal 95 ab, der dem Kanal 38 Figur 3 entspricht. Dieser mündet in einen Kraftstoffentnahmeraum 96, der in einem Zylinder 97 von einem dort dicht verschiebbaren Kolben 98 eingeschlossen wird. Der Kolben wiederum ist auf seiner Rückseite von einer Rückstellfeder 99 belastet und kann sich entgegen der Kraft dieser Feder um einen Betrag ß bis zu einem einstellbaren Anschlag 100 bewegen.A part of the pump piston protrudes into a space 91 inside the fuel injection pump. There, the pump piston carries a ring slide 92 arranged on it in the same way as the ring slide 36 according to the exemplary embodiment according to FIGS. 1 and 2. A channel 95, which corresponds to the channel 38 in FIG. 3, branches off from the inner bore 93 through which the pump piston is tightly guided . This opens into a fuel removal space 96, which is enclosed in a cylinder 97 by a piston 98 which can be moved there tightly. The piston in turn is loaded on its rear side by a return spring 99 and can move against the force of this spring by an amount β up to an adjustable stop 100.

Im Bereich der Innenbohrung 93 weist der Pumpenkolben eine Schrägnut 101 auf, in der die von der Stirnfläche 86 ausgehende Axialbohrung 89 endet.In the area of the inner bore 93, the pump piston has an oblique groove 101, in which the axial bore 89 starting from the end face 86 ends.

Der Ringschieber ist in gleicher Weise wie beim Ausführungsbeispiel nach Figur 1 bzw. 2 durch eine Stelleinrichtung verstellbar und kann entweder axial verschoben, verdreht oder in beiden Richtungen verstellt werden, je nach Ausgestaltung der Stelleinrichtung und der zu berücksichtigenden Parameter. Die Schräglage der Nut 101 erlaubt zum Beispiel eine reine Verdrehung des Ringschiebers 92, so daß durch die Verdrehung des Ringschiebers und/oder Verdrehung des Pumpenkolbens entsprechend seiner Laststellung ein größerer oder kleinerer Voreinspritzhub a wirksam wird, bis die Verbindung zwischen dem Kanal 95 und der Ringnut 101 hergestellt ist. Durch die Schrägnut kann zum Beispiel ein lastabhängiger Einfluß auf den Einspritzverlauf genommen werden. Dieser kann andererseits jedoch auch falls gewünscht durch entsprechende Verdrehung des Ringschiebers gezielt kompensiert werden. Zusätzliche Einflüsse können über eine Axialverstellung des Ringschiebers vorgenommen werden.The ring slide is adjustable in the same way as in the exemplary embodiment according to FIGS. 1 and 2 by an adjusting device and can either be axially displaced, rotated or adjusted in both directions, depending on the configuration of the adjusting device and the parameters to be taken into account. The inclined position of the groove 101 allows, for example, a pure rotation of the ring slide 92, so that a larger or smaller pre-injection stroke a becomes effective by the rotation of the ring slide and / or the rotation of the pump piston according to its load position, until the connection between the channel 95 and the ring groove 101 is manufactured. Through the oblique groove, for example, a load-dependent influence on the injection process can be exerted. On the other hand, however, this can also be compensated for in a targeted manner by rotating the ring slide accordingly. Additional influences can be made via an axial adjustment of the ring slide.

Im Auführungsbeispiel nach Figur 7 ist eine Variante für die Ausgestaltung des verstellbaren Anschlags gemäß Figuren 1, 2 und 6 gezeigt. Statt einer Ausgestaltung des Anschlag 45 zum Beispiel als einzuschraubender Stift, dessen Einschraubstellung durch eine Mutter gesichert wird, kann der entsprechende Anschlag als Bolzen 103 ausgeführt werden, der koaxial in den Zylinder 142 eintaucht und dessen Eintauchtiefe durch eine efektrisch gesteuerte Stellvorrichtung 104 gesteuert wird. Auf diese Weise kann während des laufenden Betriebs der Betrag β bzw. der Abstand der Voreinspritzung von der Haupteinspritzung variiert werden.In the exemplary embodiment according to FIG. 7, a variant for the configuration of the adjustable stop according to FIGS. 1, 2 and 6 is shown. Instead of an embodiment of the stop 45, for example as a pin to be screwed in, the screw-in position of which is secured by a nut, the corresponding stop can be designed as a bolt 103 which plunges coaxially into the cylinder 142 and its immersion depth through a efectrically controlled actuator 104 is controlled. In this way, the amount β or the distance of the pre-injection from the main injection can be varied during ongoing operation.

Claims (9)

1. Fuel injection pump for internal combustion engines having at least one pump piston (14) which limits a pump working space (15) which is connected to a fuel injection line (25) with each pump stroke of the pump piston, which can also be connected to a fuel storage space (30) during the intake stroke of the pump piston and which can be connected, from a variable part-stroke of the piston via a relief opening (46) during the delivery strokes of the pump piston to a fuel extraction space (43) which exhibits a movable wall (41), which can be brought against an adjustable stop (45) by fuel pressure of the pump working space against a restoring force, and effects an interruption in the high-pressure fuel delivery and subdivision of the fuel injection into a pre-injection and a main injection by means of fuel extraction during the pump piston delivery stroke, characterized in that the fuel injection pump exhibits a distributor (3), rotating the driven in synchronism uith the pump piston, having a distributor opening (23) which is continuously connected to the pump working space (15) and can be successively connected to one of several fuel injection lines (25) arranged on the periphery of the distributor during the pump stroke of the pump piston during the rotation of the distributor, and that the fuel extraction space (43) is located in a part (36), which is carried on the distributor and which is movable as a function of operating parameters by means of an actuating drive (54), having a duct (38) which branches away from the fuel extraction space at the opening of which operates in conjunction with a relief opening (46) of the pump working space, opening into the distributor and guided in synchronism with the pump piston drive, several relief openings being provided in accordance with the number and the distribution of the pump delivery strokes of the at least one pump piston per rotation of the distributor and one opening of the duct (38), or several duct openings (38) being provided in accordance with the number and distribution of the pump delivery strokes of the at least one pump piston per rotation of the distributor together with one relief opening (46).
2. Fuel injection pump according to Claim 1, characterized in that the movable part can be adjusted in the direction of movement of the relief opening.
3. Fuel injection pump according to Claim 1, characterized in that the movable part can be adjusted perpendicularly to the direction of movement of the relief opening.
4. Fuel injection pump according to Claim 2 or 3, characterized in that the relief opening (46) or the opening of the duct (38) are constructed as longitudinal groove.
5. Fuel injection pump according to Claim 4, characterized in that the longitudinal groove is inclined with respect to the direction of adjustment of the movable part.
6. Fuel injection pump according to one of the preceding claims, characterized in that the fuel injection pump exhibits a pump piston (14) which is actuated by a cam drive mechanism (8) driven in synchronism with the distributor drive, arranged separately from the distributor in the housing, the distributor (3) can be displaced in a guide hole (2) and exhibits on its surface area at least one first control edge (51) and at least one second control edge (52), which are limiting edges of at least one groove (20, 21) which is continuously connected to the pump working space, which, furthermore, are inclined with respect to one another and which operate in conjunction with control openings (27) branching away from the guide hole (2), which control openings lead via a line (28) to the fuel storage space (30), a beginning of delivery being defined when it is closed by the first control edge(s) and an end of delivery being defined when it is opened by the second control edge(s).
7. Fuel injection pump according to Claim 6, characterized in that at least two grooves (20, 21 ; 20', 21') diverging from one another are provided on the distributor, one of which grooves exhibits the first control edge(s) and the other one of which exhibits the second control edge(s) and, at the same time, are connected to the distributor opening (23) and to the relief opening (46).
8. Fuel injection pump according to Claim 7, characterized in that the groove(s) (21, 21') exhibiting the first control edge (51) operates in conjunction with inlet cross-sections (33), opening the surface area of the guide hole (2), of charging ducts (34) which are provided in accordance with the number and the distribution of the control openings (27) and are closed by the first control edge at the same time as the control openings (27).
9. Fuel injection pump for internal combustion engines having at least one pump piston (81) which is adjustable in its rotational position and is carried in a pump cylinder (82), which piston encloses a pump working space (88) connected to a fuel injection line with each pump delivery stroke of the pump piston and which exhibits on its surface area an opening (83) which is continuously connected to the pump working space (88) and one limiting edge (84) of which is constructed as control edge by means of which a charging or relief line (85) leading away from the pump cylinder (82) can be controlled to be open in accordance with the position of rotation of the pump piston at an earlier or later point of time of the pump piston travel, and with a duct (95), which leads away from a cylindrical wall surrounding the pump piston, the opening of which in the cylindrical wall comes to overlap a relief opening (101), which is provided on the surface area of the pump piston and is continuously connected to the pump working space (88), at an earlier or later point of time of the pump piston travel in accordance with the position of rotation of the pump piston, in which arrangement the duct (95) leads to a fuel extraction space (96), which is limited by a wall which is displaceable up to an adjustable stop (100, 104) by the fuel pressure in opposition to a restoring force, which fuel extraction space effects an interruption in the high pressure fuel delivery into the injection line and a subdivision of the fuel injection into a pre-injection and a main injection due to fuel extraction during the pump piston delivery stroke, characterized in that the fuel extraction space (96) is located in a part (92), which can be moved by means of an actuating drive (54) in dependence on operating parameters on the surface area of a part of the pump piston protruding from the pump cylinder, which part (92) exhibits the cylindrical wall and is carried with the latter on the pump piston surface area.
EP84116075A 1984-01-11 1984-12-21 Fuel-injection pump Expired EP0150471B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE3400612 1984-01-11
DE3400612 1984-01-11
DE19843444234 DE3444234A1 (en) 1984-01-11 1984-12-05 FUEL INJECTION PUMP
DE3444234 1984-12-05

Publications (3)

Publication Number Publication Date
EP0150471A2 EP0150471A2 (en) 1985-08-07
EP0150471A3 EP0150471A3 (en) 1985-08-21
EP0150471B1 true EP0150471B1 (en) 1988-07-27

Family

ID=25817470

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84116075A Expired EP0150471B1 (en) 1984-01-11 1984-12-21 Fuel-injection pump

Country Status (3)

Country Link
US (1) US4696271A (en)
EP (1) EP0150471B1 (en)
DE (2) DE3444234A1 (en)

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Also Published As

Publication number Publication date
EP0150471A2 (en) 1985-08-07
US4696271A (en) 1987-09-29
DE3444234A1 (en) 1985-07-18
EP0150471A3 (en) 1985-08-21
DE3473005D1 (en) 1988-09-01

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