EP0166995B1 - Fuel injection pump for internal-combustion engines - Google Patents

Fuel injection pump for internal-combustion engines Download PDF

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Publication number
EP0166995B1
EP0166995B1 EP85106902A EP85106902A EP0166995B1 EP 0166995 B1 EP0166995 B1 EP 0166995B1 EP 85106902 A EP85106902 A EP 85106902A EP 85106902 A EP85106902 A EP 85106902A EP 0166995 B1 EP0166995 B1 EP 0166995B1
Authority
EP
European Patent Office
Prior art keywords
relief line
pump piston
outlet
stroke
relief
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
EP85106902A
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German (de)
French (fr)
Other versions
EP0166995A3 (en
EP0166995A2 (en
Inventor
Werner Faupel
Klaus Schmidt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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Filing date
Publication date
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Publication of EP0166995A2 publication Critical patent/EP0166995A2/en
Publication of EP0166995A3 publication Critical patent/EP0166995A3/en
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Publication of EP0166995B1 publication Critical patent/EP0166995B1/en
Expired legal-status Critical Current

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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
    • 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
    • F02M41/00—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor
    • F02M41/08—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor and pumping elements being combined
    • F02M41/10—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor and pumping elements being combined pump pistons acting as the distributor
    • F02M41/12—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor and pumping elements being combined pump pistons acting as the distributor the pistons rotating to act as the distributor
    • F02M41/123—Fuel-injection apparatus with two or more injectors fed from a common pressure-source sequentially by means of a distributor the distributor and pumping elements being combined pump pistons acting as the distributor the pistons rotating to act as the distributor characterised by means for varying fuel delivery or injection timing
    • F02M41/125—Variably-timed valves controlling fuel passages
    • F02M41/126—Variably-timed valves controlling fuel passages valves being mechanically or electrically adjustable sleeves slidably mounted on rotary piston

Definitions

  • the invention is based on a fuel injection pump according to the preamble of the main claim.
  • a fuel injection pump known from FR-A-2 520 812
  • the outlet of the second relief line and the outlet of the first relief line are controlled by an end face of a ring slide forming a control edge, which is adjusted on the pump piston depending on the load and speed.
  • the second relief power provided in the known fuel injection pump serves to allow only half of the pump piston delivery strokes to become effective during idling.
  • the ring slide has grooves on its end face, via which the outlet of the second relief line is opened at the start of the pressure stroke in every second delivery stroke rotational position of the pump piston when the ring slide is in the idle operating position.
  • the entry of the second relief line at the beginning of the stroke of the pump piston is connected to the first relief line, so that the fuel delivered by the pump piston can flow out via these two lines without the build-up of high pressure.
  • These two relief lines are then separated from one another when the pump piston has covered a first, defined stroke which, in the idle state, is greater than or at most the same length as the stroke which the pump piston requires to have the first outlet of the first relief line at the ring slide valve in the idle position to open.
  • the known device thus has the goal of preventing a high pressure build-up in the pump workspace at the start of the stroke of the pump piston in idle mode and at certain rotational positions of the pump piston.
  • a similar fuel injection pump is known from DE-A-3 013 087.
  • a first and a second relief channel running in the pump piston are specified there, as well as a third relief channel which branches off directly from the pump work space and is connected via a control valve controlled by a control slide to an annular groove in the lateral surface of the cylinder guiding the pump piston.
  • the first relief channel is used to discharge the amount of fuel to be delivered to the injection nozzles via a distributor bore and also has an outlet on the pump piston surface, which is controlled by a ring slide depending on the load and / or speed.
  • the second relief channel has an inlet that comes into contact with the ring groove after a certain stroke and an outlet that is also controlled by the ring slide.
  • the exit of the second relief channel is opened towards the end of the injection stroke.
  • the third relief duct has a throttling, so that fuel can flow out in a throttled manner when the connection between the pump work space and the outlet of the second relief duct is open.
  • the possibility of allowing a partial flow of the quantity delivered by the pump piston under high pressure to flow away is limited by the control of the control spool, which completely blocks the third relief channel above idle and low partial load speed. This device requires considerable effort to control the injection rate for idling and part-load or full-load operation.
  • a fuel injection pump similar to the generic type is also known, in which the connection between the first relief channel and the second relief channel is established at the start of the stroke and is only closed after a certain stroke.
  • the outlet of the second relief line is also opened during normal operation, so that the actual start of delivery only takes place when the connection between the entrance of the second relief channel and the first relief channel is interrupted. This always takes place at the same delivery strokes of the pump piston, so that a constant start of injection is achieved.
  • This initial idle stroke is also used to provide an increased amount of fuel at the start of the internal combustion engine by adjusting the ring slide controlling the exit of the second relief channel to such an extent that the exit of the second relief channel remains permanently closed.
  • an early adjustment of the start of spraying at the start is achieved in this way.
  • This configuration has nothing to do with achieving quiet running of an internal combustion engine in the low-load range.
  • FR-A-2 287 591 discloses a fuel injection pump which, similarly to the documents mentioned above, has a first relief channel and a second relief channel.
  • a second outlet of the first relief channel can be connected to the inlet of the second relief channel via an annular groove in a cylinder leading into the pump piston.
  • the first relief channel is permanently connected to the ring groove.
  • the entry of the second relief channel only comes into contact with the annular groove when the maximum delivery stroke of the pump piston has been reached.
  • the fuel injection pump according to the invention with the characterizing features of the main claim has the advantage that the fuel injection is interrupted or reduced over a constant piston stroke at idle up to part of the part-load range and there is no change in the start of injection, since in the solution according to the invention in an advantageous manner the relief takes place over a predetermined stroke section of the pump piston after a part of the delivery stroke thereof.
  • the relief is advantageously switched off by the load-dependent control of the exit of the second relief channel at higher loads or at full load.
  • a real interruption of normal fuel injection at low load is thus achieved after a pre-injection stroke. This results in an increase in the spraying duration, which produces a quiet running of the internal combustion engine, in particular when idling.
  • This device can advantageously be implemented both for quantity control by controlling the start of injection and for quantity control by controlling the end of injection.
  • FIG. 1 shows a first exemplary embodiment with control of the end of the effective injection and control of the connection of the two relief lines to one another via an annular groove
  • FIG. 2 shows a control diagram for the exemplary embodiment according to FIG. 1
  • FIG. 3 shows a second exemplary embodiment in a modification of the exemplary embodiment according to FIG Ring groove of a defined lifting height and a slot-like outlet cross section of the first relief line, which extends in the circumferential direction
  • FIG. 4 shows a third embodiment with a slot-like ring slot and an outlet cross section of the first relief line of a defined lifting height
  • FIG. 1 shows a first exemplary embodiment with control of the end of the effective injection and control of the connection of the two relief lines to one another via an annular groove
  • FIG. 2 shows a control diagram for the exemplary embodiment according to FIG. 1
  • FIG. 3 shows a second exemplary embodiment in a modification of the exemplary embodiment according to FIG Ring groove of a defined lifting height and a slot-like outlet cross section of the first relief line,
  • FIG. 5 shows a fourth embodiment with an essentially axially extending bypass channel in the Wall of the cylinder for controlling the connection of the first relief line to the second relief line
  • Figure 6 shows a fifth embodiment in modification of the embodiment of Figure 5, in which the duration d
  • FIG. 7 shows a sixth exemplary embodiment of the invention with a fuel injection pump which is designed to control the start of injection for metering fuel quantity
  • FIG. 8 shows a control diagram for the exemplary embodiment according to FIG. 7.
  • a pump piston 4 is arranged in a cylinder 2 of a cylinder liner 3 inserted into the pump housing, which is set into a reciprocating and at the same time rotating movement by means not shown.
  • the pump piston encloses a pump working chamber 5 on its one end face and partially protrudes out of the cylinder 2 into a pump suction chamber 7. It is also driven at this end of the pump piston.
  • the pump working chamber 5 is supplied with fuel via longitudinal grooves 8 arranged in the lateral surface of the pump piston and a suction bore 9 running through the cylinder liner 3 in the housing 1, as long as the pump piston executes its suction stroke or assumes its bottom dead center position.
  • the suction bore opens into the pump suction chamber 7 at its other end.
  • the pump suction chamber is supplied with fuel from a fuel tank 12 via a feed pump 11.
  • a pressure control valve 13 controls the pressure in the suction chamber in a known manner.
  • a longitudinal channel 15 leads from the working space 5 in the pump piston, which is designed as a blind bore and can be referred to as the first relief line. From this branches off a radial bore 16 which leads to a distributor opening 17 in the outer surface of the pump piston 4. In the working area of this distributor opening branch off in a radial plane of the cylinder 2 delivery lines 19, which are arranged distributed around the circumference of the cylinder according to the number of cylinders to be supplied with fuel of the associated internal combustion engine. The delivery lines 19 each lead via a valve 21, which is designed as a check valve or pressure relief valve in a known manner, to the fuel injection points, not shown.
  • a radial bore 22 branches off, which opens into a first outlet D in the lateral surface of the pump piston, specifically in the region of the part of the pump piston that projects into the pump suction chamber.
  • a quantity adjustment element in the form of a ring slide 24 is arranged on the pump piston, which can be displaced tightly on the pump piston and forms a control edge 25 with its upper end face, through which the outlet D is controlled.
  • the axial position of the ring slide 24 is determined in a known manner by a control lever 27 which can be pivoted about an axis 28 fixed to the housing and which is coupled to the ring slide via a ball head 29 at the end of its one lever arm.
  • the ring slide is adjusted by load and / or speed depending on a controller (not shown further here).
  • the ring slide 24 assumes an upper position near the pump working space, from which it is increasingly adjusted downwards as the load decreases.
  • the available useful stroke h n which the pump piston or the outlet cross section D must cover from the bottom dead center of the pump piston, thus changes in order to be opened by the control edge 25 of the ring slide.
  • a third radial bore 31 branches off from the first relief line 15 and opens into a second outlet B on the lateral surface of the pump piston 4.
  • a second relief line 33 is provided in the pump piston 4, which has an inlet A in the area of the pump piston jacket surface that is constantly located in the cylinder 2 and an outlet C in the working area of the ring slide 24. This is offset by a constant amount h " relative to the first outlet D of the first relief line towards the pump work chamber, so that the outlet C from the control edge 25 is always opened first in the course of the pump piston stroke before the first outlet D is opened.
  • annular groove 37 is arranged in the wall of the cylinder 2.
  • the inlet A and the second outlet B are assigned to one another such that when the inlet A just overlaps the bottom edge of the annular groove 37 in the course of the pump stroke of the pump piston, the second outlet B of the first relief line already overlaps with the annular groove 37 is located and after an intended stroke of the pump piston h e comes out of the overlap with the annular groove 27, a point where the inlet A of the second relief line 33 is still in overlap with the annular groove 37. In this way, a connection is established between the first relief line 15 and the second relief line 33 for the predetermined lifting section of size h e .
  • the assignment of the cross sections and control edges mentioned can be seen from the diagram in FIG. 2.
  • the assignment of the cross sections in the course of the pump piston stroke is plotted over the load or the position of the ring slide.
  • LL means idle and VL means full load.
  • the start of injection takes place, which can, for example, coincide with the start of the stroke of the pump piston from its bottom dead center.
  • the pump working chamber 5 previously filled via the suction bore 9 and the longitudinal grooves 8 is then connected to one of the delivery lines 19 via the first relief line 15, the radial bore 16, the distributor groove 17, in accordance with the rotational position of the pump piston.
  • Line C represents the opening point of the outlet C of the second relief line 33. This line rises with increasing load in accordance with the position of the ring slide 24 which is adjustable with the load. D also shows the opening point D of the first discharge line 15. This line runs parallel to line C and indicates the possible useful stroke h n . This useful stroke is indicated in FIG. 1 provided that the pump piston assumes its bottom dead center in the position shown. For the case shown, a broken position of the ring slide 24 was assumed.
  • Line SB Parallel to line SB is a line A, which marks the opening point of the inlet A of the second relief line 33.
  • the line B parallel thereto indicates the piston stroke at which the second outlet of the first relief line is closed.
  • the stroke range between A and B, the stroke h e there is a connection between the first relief line 15 and the second relief line 33. Only within this stroke range can the fuel delivered by the pump piston in this area or a part thereof flow out via the second relief line 33.
  • this is only possible with a second condition, if the outlet C of the second relief line is also open, that is to say that from the point of intersection of the line C with the line B, it is no longer possible for fuel to flow out.
  • This point G is still before the full load point, so that the entire working capacity of the pump piston can be used for fuel delivery in the upper load range and at full load.
  • the relief range between lines A and B is within the range between C and D, so that a constant amount of fuel per delivery stroke of the pump piston is initially diverted over this range until line C leads to line A. intersects at point F. Between F and G the amount of relief becomes increasingly smaller.
  • the location of the area h e and its usable height can be optimized with regard to a quiet combustion process at low load and without influencing the injection start control, which, for. B. can be done by a separate spray start adjuster of known design.
  • FIG. 3 shows another type of connection between the first relief line 15 and the second relief line 33 in a partial section of the piston.
  • the annular groove 37 has a defined height he '
  • the inlet A' of the second relief line 33 is widened in the stroke direction, so that it remains in constant communication with the annular groove 37 and the second outlet B 'of the first relief line 15 is designed in the form of a slot.
  • the second relief line 33 thus remains in constant connection with the annular groove 37.
  • the duration of the connection between the first relief line 15 and the second relief line 33 is now determined by the slot-shaped second outlet B 'during the overlap h e with the Ring groove 37 determined.
  • This embodiment has the advantage that the control times of the overlap can be made more precise here, because of the slot-like design of the second outlet B ', a rapid opening takes place, as a result of which the influence of the speed on the discharge quantity is reduced. Due to the slot-like design, a throttle cross-section can also advantageously be determined, which controls the degree of relief via the rub h e .
  • FIG. 4 shows an equivalent configuration to the exemplary embodiment according to FIG. 3. There, it is not the second outlet D but the annular groove 37 ′ which is slot-shaped and the width of the second outlet B of size h b determines the duration of the overlap h e .
  • a fourth exemplary embodiment of the connection between the first relief line 15 and the second relief line 33 is the solution according to FIG. 5.
  • a bypass channel 39 is provided there in the cylinder liner 3 and extends parallel to the axis of the pump piston.
  • the bypass channel opens into a first annular groove 41 on the pump work space and at its other end in a second annular groove 42 located on the pump suction chamber side second outlet B has overlapped with the first annular groove 41, the inlet A is only over one stroke h e overlapped with the second annular groove 42.
  • the assignment can of course also be done in the opposite sense. It is only essential that the coverage area h e is observed.
  • the annular grooves 41 and 42 can also be provided in an equivalent manner on the pump piston.
  • the embodiment according to FIG. 6 can also be carried out in such a way that the second outlet B 'of the first relief line 15 is again slit-shaped and the bypass duct 39 on the pump work chamber side, likewise in the form of a slot 44 of the same width, is realized.
  • the other end of the bypass channel 39 ' is connected to the second relief line 33 via the inlet A regardless of the pump piston stroke.
  • the width of the slot B 'or 44 determines the duration of the overlap h e .
  • the sixth exemplary embodiment according to FIG. 7 shows that the device described above for generating a quiet running of the internal combustion engine at idle and in the partial load range can also be implemented when the ring slide 24 "does not mean the end of the delivery of the pump piston to an earlier or later one Point before TDC controls, but the beginning of the delivery of the pump piston after a more or less large idle stroke of the pump piston.
  • the configuration of the fuel injection pump with pump piston 4 ', cylinder 2 and ring slide 24 is essentially the same as in the exemplary embodiment according to FIG here the ring slide is operated in reverse logic by the control lever 27. In a departure from the exemplary embodiment according to FIG.
  • the first outlet D is arranged in such a way that when the pump piston delivery stroke begins, it is first closed by the control edge 25" which is now below, before the control edge 25 "controls the subsequent outlet C" of the second relief line 33 " constructive stroke difference is also called hy here in the same way as in the exemplary embodiment according to FIG. 1, the inlet A "of the second relief line 33" and the second outlet B “of the first relief line 15" are arranged in the working area to the annular groove 37.
  • FIG. 8 shows a diagram corresponding to FIG. 2 for this embodiment.
  • the line D "runs according to the variable position of the ring slide 24" inclined towards full load VL. Tilted in the same way
  • the line C which marks the closing point of the outlet C", runs with the distance h " to the closing point line of the first outlet cross section D".
  • FE denotes a line running parallel to the abscissa, which indicates the constructive delivery end of the pump piston.
  • Line A "and line B" are also shown in the diagram as lines parallel to line FE.
  • A denotes the point at which the inlet A” comes into contact with the annular groove 37, where at the same time the connection between the second outlet B "and the annular groove 37 still exists and the line B" denotes the point at which the second Exit B "is closed and the connection between the first relief line 15" and the second relief line 33 is prevented.
  • a reduction in the resulting injection rate at idle and low load due to temporarily interrupted or reduced delivery also results in this embodiment of a fuel injection pump. Deviating from the exemplary embodiment according to FIG. 1, however, the pre-injection quantity before the relief is dependent on the load.

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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)
  • High-Pressure Fuel Injection Pump Control (AREA)

Description

Stand der TechnikState of the art

Die Erfindung geht von einer Kraftstoffeinspritzpumpe nach der Gattung des Hauptanspruchs aus. Bei einer solchen, durch die FR-A-2 520 812 bekannten Kraftstoffeinspritzpumpe werden der Austritt der zweiten Entlastungsleitung und der Austritt der ersten Entlastungsleitung durch eine eine Steuerkante bildende Stirnfläche eines Ringschiebers gesteuert, der auf dem Pumpenkolben last- und drehzahlabhängig verstellt wird. Die bei der bekannten Kraftstoffeinspritzpumpe vorgesehene zweite Entlastungsleistung dient dazu, im Leerlaufbetrieb nur die Hälfte der Pumpenkolbenförderhübe einspritzwirksam werden zu lassen. Dazu weist der Ringschieber an seiner Stirnseite Nuten auf, über die in jeder zweiten Förderhubdrehstellung des Pumpenkolbens bei Leerlaufbetriebsstellung des Ringschiebers der Austritt der zweiten Entlastungsleitung mit Beginn des Druckhubes geöffnet ist. Zugleich ist der Eintritt der zweiten Entlastungsleitung mit Hubbeginn des Pumpenkolbens mit der ersten Entlastungsleitung verbunden, so daß über diese beiden Leitungen der vom Pumpenkolben geförderte Kraftstoff ohne Hochdruckaufbau abströmen kann. Diese beiden Entlastungsleitungen werden dann voneinander getrennt, wenn der Pumpenkolben einen ersten, festgelegten Hub zurückgelegt hat, der für den Leerlauffall größer oder höchstens gleich groß ist wie der Hub, den der Pumpenkolben benötigt, um am im Leerlaufstellung stehenden Ringschieber den ersten Austritt der ersten Entlastungsleitung zu öffnen. Die bekannte Einrichtung hat somit das Ziel, mit Hubbeginn des Pumpenkolbens im Leerlaufbetrieb und bei bestimmten Drehstellungen des Pumpenkolbens einen Hochdruck aufbau im Pumpenarbeitsraum zu verhindern.The invention is based on a fuel injection pump according to the preamble of the main claim. In such a fuel injection pump known from FR-A-2 520 812, the outlet of the second relief line and the outlet of the first relief line are controlled by an end face of a ring slide forming a control edge, which is adjusted on the pump piston depending on the load and speed. The second relief power provided in the known fuel injection pump serves to allow only half of the pump piston delivery strokes to become effective during idling. For this purpose, the ring slide has grooves on its end face, via which the outlet of the second relief line is opened at the start of the pressure stroke in every second delivery stroke rotational position of the pump piston when the ring slide is in the idle operating position. At the same time, the entry of the second relief line at the beginning of the stroke of the pump piston is connected to the first relief line, so that the fuel delivered by the pump piston can flow out via these two lines without the build-up of high pressure. These two relief lines are then separated from one another when the pump piston has covered a first, defined stroke which, in the idle state, is greater than or at most the same length as the stroke which the pump piston requires to have the first outlet of the first relief line at the ring slide valve in the idle position to open. The known device thus has the goal of preventing a high pressure build-up in the pump workspace at the start of the stroke of the pump piston in idle mode and at certain rotational positions of the pump piston.

Eine ähnliche Kraftstoffeinspritzpumpe ist durch die DE-A-3 013 087 bekannt. Dort sind ein erster und ein zweiter, im Pumpenkolben verlaufender Entlastungskanal vorgegeben sowie ein dritter Entlastungskanal, der unmittelbar vom Pumpenarbeitsraum abzweigt und über eine durch einen Steuerschieber gesteuerte Steuerstelle mit einer Ringnut in der Mantelfläche des den Pumpenkolben führenden Zylinders verbunden ist. Der erste Entlastungskanal dient dabei zur Ableitung der zu Einspritzdüsen zu fördernden Kraftstoffmenge über eine Verteilerbohrung und weist zudem einen Austritt an der Pumpenkolbenmantelfläche auf, der durch einen Ringschieber last- und/oder drehzahlabhängig gesteuert wird. Der zweite Entlastungskanal hat einen Eintritt, der ab einem bestimmten Hub mit der Ringnut in Verbindung kommt und einen Austritt, der ebenfalls vom Ringschieber gesteuert wird. Während der Eintritt des ersten Entlastungskanals erst nach Zurücklegen eines bestimmten Hubes des Pumpenkolbens nach Beginn der Einspritzung mit der Ringnut in Verbindung kommt, wird der Austritt des zweiten Entlastungskanals gegen Ende des Einspritzhubes geöffnet. Ferner weist der dritte Entlastungskanal eine Drosselung auf, so daß bei geöffneter Verbindung zwischen Pumpenarbeitsraum und Austritt des zweiten Entlastungskanals gedrosselt Kraftstoff abströmen kann. Die Möglichkeit, hiermit durch gedrosseltes Abströmenlassen einer Teilmenge der vom Pumpenkolben unter Hochdruck geförderten Menge abströmen zu lassen, wird begrenzt durch die Steuerung des Steuerschiebers, durch den oberhalb der Leerlauf- und der niedrigen Teillastdrehzahl der dritte Entlastungskanal ganz gesperrt wird. Diese Einrichtung bedingt einen erheblichen Aufwand zur Steuerung der Einspritzrate für den Leerlaufbetrieb und den Teillast- bzw. Vollastbetrieb.A similar fuel injection pump is known from DE-A-3 013 087. A first and a second relief channel running in the pump piston are specified there, as well as a third relief channel which branches off directly from the pump work space and is connected via a control valve controlled by a control slide to an annular groove in the lateral surface of the cylinder guiding the pump piston. The first relief channel is used to discharge the amount of fuel to be delivered to the injection nozzles via a distributor bore and also has an outlet on the pump piston surface, which is controlled by a ring slide depending on the load and / or speed. The second relief channel has an inlet that comes into contact with the ring groove after a certain stroke and an outlet that is also controlled by the ring slide. While the entry of the first relief channel only comes into contact with the annular groove after covering a certain stroke of the pump piston after the start of injection, the exit of the second relief channel is opened towards the end of the injection stroke. Furthermore, the third relief duct has a throttling, so that fuel can flow out in a throttled manner when the connection between the pump work space and the outlet of the second relief duct is open. The possibility of allowing a partial flow of the quantity delivered by the pump piston under high pressure to flow away is limited by the control of the control spool, which completely blocks the third relief channel above idle and low partial load speed. This device requires considerable effort to control the injection rate for idling and part-load or full-load operation.

Durch die DE-A-2 644 698 ist ferner eine Kraftstoffeinspritzpumpe ähnlich der gattungsgemäßen Art bekannt, bei der die Verbindung zwischen dem ersten Entlastungskanal und dem zweiten Entlastungskanal mit Hubbeginn hergestellt wird und erst ab einem bestimmten Hub verschlossen wird. Mit Hubbeginn ist bei Normalbetrieb aber auch der Austritt der zweiten Entlastungsleitung geöffnet, so daß der eigentliche Förderbeginn erst dann erfolgt, wenn die Verbindung zwischen dem Eintritt des zweiten Entlastungskanals und dem ersten Entlastungskanal unterbrochen ist. Dies erfolgt zu immer gleichen Förderhüben des Pumpenkolbens, so daß ein konstanter Einspritzbeginn erreicht wird. Dieser anfängliche Leerhub wird auch dazu benutzt, beim Start der Brennkraftmaschine eine erhöhte Kraftstoffmenge zur Verfügung zu stellen, indem der den Austritt des zweiten Entlastungskanals steuernde Ringschieber soweit verstellt wird, daß der Austritt des zweiten Entlastungskanals ständig verschlossen bleibt. Zugleich wird auf diese Art und Weise eine Frühverstellung des Spritzbeginns beim Start erzielt. Diese Ausgestaltung hat nichts mit der Erzielung eines leisen Laufes einer Brennkraftmaschine im Niedriglastbereich zu tun.From DE-A-2 644 698 a fuel injection pump similar to the generic type is also known, in which the connection between the first relief channel and the second relief channel is established at the start of the stroke and is only closed after a certain stroke. At the start of the stroke, however, the outlet of the second relief line is also opened during normal operation, so that the actual start of delivery only takes place when the connection between the entrance of the second relief channel and the first relief channel is interrupted. This always takes place at the same delivery strokes of the pump piston, so that a constant start of injection is achieved. This initial idle stroke is also used to provide an increased amount of fuel at the start of the internal combustion engine by adjusting the ring slide controlling the exit of the second relief channel to such an extent that the exit of the second relief channel remains permanently closed. At the same time, an early adjustment of the start of spraying at the start is achieved in this way. This configuration has nothing to do with achieving quiet running of an internal combustion engine in the low-load range.

Durch die FR-A-2 287 591 ist schließlich eine Kraftstoffeinspritzpumpe bekannt, die ähnlich wie bei den vorherstehend genannten Schriften einen ersten Entlastungskanal und einen zweiten Entlastungskanal aufweist. Auch in diesem Falle ist ein zweiter Austritt des ersten Entlastungskanals über eine Ringnut in einen in den Pumpenkolben führenden Zylinder mit dem Eintritt des zweiten Entlastungskanals verbindbar. Dabei ist der erste Entlastungskanal ständig mit der Ringnut verbunden. Der Eintritt des zweiten Entlastungskanals hingegen kommt erst mit der Ringnut in Verbindung, wenn der maximale Förderhub des Pumpenkolbens erreicht ist. Diese Einrichtung arbeitet ähnlich wie die in der vorgenannten Druckschrift beschriebene Einrichtung nur, daß im vorliegenden Falle eine Einspritzbeginnsteuerung verwirklicht ist, indem der erste Entlastungskanal bei Hubbeginn des Pumpenkolbens zunächst über seinen Austritt mit der Entlastungsseite verbunden ist und erst je nach Stellung des Ringschiebers früher oder später geschlossen wird. Für den restlichen Hubverlauf erfolgt dann eine Hochdruckeinspritzung in eine von dem Pumpenkolben angesteuerte Einspritzleitung. Der zweite Entlastungskanal ist mit seinem Austritt ebenfalls zu Beginn des Pumpenkolbenhubs mit der Entlastungsseite verbunden und wird ebenfalls erst nach einem anfänglichen Hub durch den Ringschieber geschlossen. Dieses Schließen erfolgt jedoch zu einem späteren Hub als das Schließen des ersten Entlastungskanals, so daß, wenn der Eintritt des zweiten Entlastungskanals die Ringnut erreicht hat, der Pumpenarbeitsraum über diesen zweiten Entlastungskanal und seinen Austritt zur Beendigung der Hochdruckförderung entlastet werden kann. Mit dieser Einrichtung soll ein konstantes Förderende erzielt werden.Finally, FR-A-2 287 591 discloses a fuel injection pump which, similarly to the documents mentioned above, has a first relief channel and a second relief channel. In this case too, a second outlet of the first relief channel can be connected to the inlet of the second relief channel via an annular groove in a cylinder leading into the pump piston. The first relief channel is permanently connected to the ring groove. The entry of the second relief channel, on the other hand, only comes into contact with the annular groove when the maximum delivery stroke of the pump piston has been reached. This facility works similarly to that in the The above-mentioned publication only describes that in the present case an injection start control is realized by the first relief channel at the start of the stroke of the pump piston first being connected to the relief side via its outlet and being closed sooner or later depending on the position of the ring slide. A high-pressure injection into an injection line controlled by the pump piston then takes place for the remaining stroke. The outlet of the second relief channel is also connected to the relief side at the beginning of the pump piston stroke and is also only closed by the ring slide after an initial stroke. However, this closing takes place at a later stroke than the closing of the first relief channel, so that when the entry of the second relief channel has reached the annular groove, the pump work space can be relieved via this second relief channel and its exit to end the high-pressure delivery. This facility is intended to achieve a constant end of funding.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Kraftstoffeinspritzpumpe mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, daß im Leerlauf bis zu einem Teil des Teillastbereiches die Kraftstoffeinspritzung über einen konstanten Kolbenhub unterbrochen oder reduziert wird und dabei eine Veränderung des Spritzbeginns nicht erfolgt, da bei der erfindungsgemäßen Lösung in vorteilhafter Weise die Entlastung über einen vorgegebenen Hubabschnitt des Pumpenkolbens nach einem Teil des Förderhubs desselben erfolgt. Auch hier erfolgt vorteilhafterweise die Abschaltung der Entlastung durch die lastabhängige Steuerung des Austritts des zweiten Entlastungskanals bei höherer Last bzw. bei Vollast. Es wird somit nach einem Voreinspritzhub eine echte Unterbrechung der normalen Kraftstoffeinspritzung bei Niedriglast erreicht. Das ergibt eine Spritzdauerverlängerung, die insbesondere im Leerlaufbetrieb einen leisen Lauf der Brennkraftmaschine erzeugt. In vorteilhafter Weise läßt sich diese Einrichtung sowohl für eine Mengensteuerung durch Steuerung des Einspritzbeginns als auch für eine .Mengensteuerung durch Steuerung des Spritzendes verwirklichen.The fuel injection pump according to the invention with the characterizing features of the main claim has the advantage that the fuel injection is interrupted or reduced over a constant piston stroke at idle up to part of the part-load range and there is no change in the start of injection, since in the solution according to the invention in an advantageous manner the relief takes place over a predetermined stroke section of the pump piston after a part of the delivery stroke thereof. Here, too, the relief is advantageously switched off by the load-dependent control of the exit of the second relief channel at higher loads or at full load. A real interruption of normal fuel injection at low load is thus achieved after a pre-injection stroke. This results in an increase in the spraying duration, which produces a quiet running of the internal combustion engine, in particular when idling. This device can advantageously be implemented both for quantity control by controlling the start of injection and for quantity control by controlling the end of injection.

Durch die in den Unteranssprüchen aufgeführten Maßnahmen sind vorteilhafte Ausgestaltungen der Erfindung bezüglich der Erzeugung der Verbindung zwischen dem ersten Entlastungskanal und dem zweiten Entlastungskanal über den vorgegebenen Hubabschnitt gekennzeichnet.The measures listed in the subclaims characterize advantageous refinements of the invention with regard to the production of the connection between the first relief channel and the second relief channel via the predetermined lifting section.

Zeichnungdrawing

Sechs Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und werden in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 ein erstes Ausführungsbeispiel mit Steuerung des Endes der wirksamen Einspritzung und Steuerung der Verbindung der beiden Entlastungsleitungen miteinander über eine Ringnut, Figur 2 ein Steuerdiagramm zum Ausführungsbeispiel nach Figur 1, Figur 3 ein zweites Ausführungsbeispiel in Abwandlung zum Ausführungsbeispiel nach Figur 1 mit einer Ringnut definierter Hubhöhe und einem schlitzartigen sich in Umfangsrichtung erstreckenden Austrittsquerschnitt der ersten Entlastungsleiung, Figur 4 ein drittes Ausführungsbeispiel mit einer schlitzartigen Ringnut und einem Austrittsquerschnitt der ersten Entlastungsleitung von einer definierten Hubhöhe, Figur 5 ein viertes Ausführungsbeispiel mit einem sich im wesentlichen axial erstreckenden Bypasskanal in der Wand des Zylinders zur Steuerung der Verbindung der ersten Entlastungsleitung mit der zweiten Entlastungsleitung, Figur 6 ein fünftes Ausführungsbeispiel in Abwandlung zum Ausführungsbeispiel nach Figur 5, bei dem die Dauer der Uberdeckung durch Schlitzsteuerung erfolgt, Figur 7 ein sechstes Ausführungsbeispiel der Erfindung mit einer Kraftstoffeinspritzpumpe, die auf die Steuerung des Spritzbeginns zur Kraftstoffmengendosierung ausgelegt ist und Figur 8 ein Steuerdiagramm zum Ausführungsbeispiel nach Figur 7.Six exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the description below. 1 shows a first exemplary embodiment with control of the end of the effective injection and control of the connection of the two relief lines to one another via an annular groove, FIG. 2 shows a control diagram for the exemplary embodiment according to FIG. 1, FIG. 3 shows a second exemplary embodiment in a modification of the exemplary embodiment according to FIG Ring groove of a defined lifting height and a slot-like outlet cross section of the first relief line, which extends in the circumferential direction, FIG. 4 shows a third embodiment with a slot-like ring slot and an outlet cross section of the first relief line of a defined lifting height, FIG. 5 shows a fourth embodiment with an essentially axially extending bypass channel in the Wall of the cylinder for controlling the connection of the first relief line to the second relief line, Figure 6 shows a fifth embodiment in modification of the embodiment of Figure 5, in which the duration d FIG. 7 shows a sixth exemplary embodiment of the invention with a fuel injection pump which is designed to control the start of injection for metering fuel quantity, and FIG. 8 shows a control diagram for the exemplary embodiment according to FIG. 7.

Beschreibungdescription

In einem Gehäuse 1 einer Kraftstoffeinspritzpumpe ist in einem Zylinder 2 einer in das Pumpengehäuse eingesetzten Zylinderbüchse 3 ein Pumpenkolben 4 angeordnet, der durch nicht dargestellte Mittel in eine hin- und hergehende und zugleich rotierende Bewegung versetzt wird. Der Pumpenkolben schließt auf seiner einen Stirnseite einen Pumpenarbeitsraum 5 ein und ragt zum Teil aus dem Zylinder 2 heraus in einen Pumpensaugraum 7. An diesem Ende des Pumpenkolbens erfolgt auch sein Antrieb.In a housing 1 of a fuel injection pump, a pump piston 4 is arranged in a cylinder 2 of a cylinder liner 3 inserted into the pump housing, which is set into a reciprocating and at the same time rotating movement by means not shown. The pump piston encloses a pump working chamber 5 on its one end face and partially protrudes out of the cylinder 2 into a pump suction chamber 7. It is also driven at this end of the pump piston.

Der Pumpenarbeitsraum 5 wird über in der Mantelfläche des Pumpenkolbens angeordnete Längsnuten 8 und eine durch die Zylinderbüchse 3 im Gehäuse 1 verlaufende Saugbohrung 9 mit Kraftstoff versorgt, solange der Pumpenkolben seinen Saughub ausführt bzw. seine untere Totpunktlage einnimmt. Die Saugbohrung mündet an ihrem anderen Ende in den Pumpensaugraum 7. Der Pumpersaugraum wird über eine Förderpumpe 11 aus einem Kraftstoffbehälter 12 mit Kraftstoff versorgt. Durch ein Drucksteuerventil 13 wird der Druck im Saugraum in bekannter Weise gesteuert.The pump working chamber 5 is supplied with fuel via longitudinal grooves 8 arranged in the lateral surface of the pump piston and a suction bore 9 running through the cylinder liner 3 in the housing 1, as long as the pump piston executes its suction stroke or assumes its bottom dead center position. The suction bore opens into the pump suction chamber 7 at its other end. The pump suction chamber is supplied with fuel from a fuel tank 12 via a feed pump 11. A pressure control valve 13 controls the pressure in the suction chamber in a known manner.

Vom Arbeitsraum 5 führt im Pumpenkolben ein Längskanal 15 ab, der als Sackbohrung ausgebildet ist und als erste Entlastungsleitung zu bezeichnen ist. Von dieser zweigt eine radiale Bohrung 16 ab, die zu einer Verteileröffnung 17 in der Mantelfläche des Pumpenkolbens 4 führt. Im Arbeitsbereich dieser Verteileröffnung zweigen in einer radialen Ebene des Zylinders 2 Förderleitungen 19 ab, die entsprechend der Zahl der mit Kraftstoff zu versorgenden Zylinder der zugehörigen Brennkraftmaschine am Umfang des Zylinders verteilt angeordnet sind. Die Förderleitungen 19 führen über je ein Ventil 21, das als Rückschlagventil oder Druckentlastungsventil in bekannter Weise ausgestaltet ist, zu den nicht gezeigten Kraftstoffeinspritzstellen.A longitudinal channel 15 leads from the working space 5 in the pump piston, which is designed as a blind bore and can be referred to as the first relief line. From this branches off a radial bore 16 which leads to a distributor opening 17 in the outer surface of the pump piston 4. In the working area of this distributor opening branch off in a radial plane of the cylinder 2 delivery lines 19, which are arranged distributed around the circumference of the cylinder according to the number of cylinders to be supplied with fuel of the associated internal combustion engine. The delivery lines 19 each lead via a valve 21, which is designed as a check valve or pressure relief valve in a known manner, to the fuel injection points, not shown.

Am Ende der ersten Entlastungsleitung zweigt eine Radialbohrung 22 ab, die in einen ersten Austritt D in der Mantelfläche des Pumpenkolbens mündet, und zwar im Bereich des in den Pumpensaugraum ragenden Teils des Pumpenkolbens. In diesem Bereich ist auf dem Pumpenkolben ein Mengenverstellorgan in Form eines Ringschiebers 24 angeordnet, der dicht auf dem Pumpenkolben verschiebbar ist und mit seiner oberen Stirnseite eine Steuerkante 25 bildet, durch die der Austritt D gesteuert wird. Die Axialstellung des Ringschiebers 24 wird durch einen Reglerhebel 27 in bekannter Weise bestimmt, der um eine gehäusefeste Achse 28 schwenkbar ist und über einen Kugelkopf 29 am Ende seines einen Hebelarmes mit dem Ringschieber gekoppelt ist. In bekannter Weise erfolgt die Verstellung des Ringschiebers durch einen hier nicht weiter gezeigten Regler lastund/oder drehzahlabhängig. Bei gewünschter hoher Kraftstoffeinspritzmenge nimmt dabei der Ringschieber 24 eine obere, pumpenarbeisraumnahe Stellung ein, von der er bei abnehmender Last zunehmend nach unten verstellt wird. Damit verändert sich der jeweils zur Verfügung stehende Nutzhub hn, den der Pumpenkolben bzw. der Austrittsquerschnitt D vom unteren Totpunkt des Pumpenkolbens zurücklegen muß, um von der Steuerkante 25 des Ringschiebers aufgesteuert zu werden.At the end of the first relief line, a radial bore 22 branches off, which opens into a first outlet D in the lateral surface of the pump piston, specifically in the region of the part of the pump piston that projects into the pump suction chamber. In this area, a quantity adjustment element in the form of a ring slide 24 is arranged on the pump piston, which can be displaced tightly on the pump piston and forms a control edge 25 with its upper end face, through which the outlet D is controlled. The axial position of the ring slide 24 is determined in a known manner by a control lever 27 which can be pivoted about an axis 28 fixed to the housing and which is coupled to the ring slide via a ball head 29 at the end of its one lever arm. In a known manner, the ring slide is adjusted by load and / or speed depending on a controller (not shown further here). At the desired high fuel injection quantity, the ring slide 24 assumes an upper position near the pump working space, from which it is increasingly adjusted downwards as the load decreases. The available useful stroke h n , which the pump piston or the outlet cross section D must cover from the bottom dead center of the pump piston, thus changes in order to be opened by the control edge 25 of the ring slide.

Von der ersten Entlastungsleitung 15 zweigt eine dritte Radialbohrung 31 ab, die in einem zweiten Austritt B an der Mantelfläche des Pumpenkolbens 4 mündet. Weiterhin ist im Pumpenkolben 4 eine zweite Entlastungsleitung 33 vorgesehen, die im Bereich der ständig sich im Zylinder 2 befindlichen Pumpenkolben- Mantelfläche einen Eintritt A hat und im Arbeitsbereich des Ringschiebers 24 einen Austritt C hat. Dieser ist um den konstanten Betrag h" gegenüber dem ersten Austritt D der ersten Entlastungsleitung zum Pumpenarbeitsraum hin versetzt, so daß im Laufe des Pumpenkolbenhubs immer der Austritt C von der Steuerkante 25 zuerst aufgesteuert wird, bevor der erste Austritt D aufgesteuert wird.A third radial bore 31 branches off from the first relief line 15 and opens into a second outlet B on the lateral surface of the pump piston 4. Furthermore, a second relief line 33 is provided in the pump piston 4, which has an inlet A in the area of the pump piston jacket surface that is constantly located in the cylinder 2 and an outlet C in the working area of the ring slide 24. This is offset by a constant amount h " relative to the first outlet D of the first relief line towards the pump work chamber, so that the outlet C from the control edge 25 is always opened first in the course of the pump piston stroke before the first outlet D is opened.

Im Hubbereich des Eintritts A der zweiten Entlastungsleitung und des zweiten Austritts B der ersten Entlastungsleitung ist in der Wand des Zylinders 2 eine Ringnut 37 angeordnet. Der Eintritt A und der zweite Austritt B sind dabei einander so zugeordnet, daß, wenn im Laufe des Pumphubs des Pumpenkolbens der Eintritt A gerade in Überdeckung mit der untersten Kante der Ringnut 37 kommt, der zweite Austritt B der ersten Entlastungsleitung sich bereits in Überdeckung mit der Ringnut 37 befindet und nach einem vorgesehenen Hub des Pumpenkolbens he wieder aus der Überdeckung mit der Ringnut 27 gerät, einem Punkt, wo sich der Eintritt A der zweiten Entlastungsleitung 33 noch in Überdeckung mit der Ringnut 37 befindet. Auf diese Weise wird für den vorgegebenen Hubabschnitt der Größe he eine Verbindung zwischen der ersten Entlastungsleitung 15 und der zweiten Entlastungsleitung 33 hergestellt.In the stroke area of the inlet A of the second relief line and the second outlet B of the first relief line, an annular groove 37 is arranged in the wall of the cylinder 2. The inlet A and the second outlet B are assigned to one another such that when the inlet A just overlaps the bottom edge of the annular groove 37 in the course of the pump stroke of the pump piston, the second outlet B of the first relief line already overlaps with the annular groove 37 is located and after an intended stroke of the pump piston h e comes out of the overlap with the annular groove 27, a point where the inlet A of the second relief line 33 is still in overlap with the annular groove 37. In this way, a connection is established between the first relief line 15 and the second relief line 33 for the predetermined lifting section of size h e .

Die Zuordnung der erwähnten Querschnitte und Steuerkanten ist dem Diagramm in Figur 2 zu entnehmen. Dort ist über der Last bzw. der Stellung des Ringschiebers die Zuordnung der Querschnitte in Verlauf des Pumpenkolbenhubs aufgetragen. LL bedeutet dabei Leerlauf und VL bedeutet Vollast. Bei der waagrecht verlaufenden Linie SB erfolgt der Spritzbeginn, was beispielsweise mit dem Hubbeginn des Pumpenkolbens aus seinem unteren Totpunkt heraus übereinstimmen kann. Der zuvor über die Saugbohrung 9 und die Längsnuten 8 gefüllte Pumpenarbeitsraum 5 wird dann entsprechend der Drehstellung des Pumpenkolbens über die erste Entlastungsleitung 15, die Radialbohrung 16, die Verteilernut 17 mit einer der Förderleitungen 19 verbunden.The assignment of the cross sections and control edges mentioned can be seen from the diagram in FIG. 2. The assignment of the cross sections in the course of the pump piston stroke is plotted over the load or the position of the ring slide. LL means idle and VL means full load. In the case of the horizontally running line SB, the start of injection takes place, which can, for example, coincide with the start of the stroke of the pump piston from its bottom dead center. The pump working chamber 5 previously filled via the suction bore 9 and the longitudinal grooves 8 is then connected to one of the delivery lines 19 via the first relief line 15, the radial bore 16, the distributor groove 17, in accordance with the rotational position of the pump piston.

Mit der Linie C ist der Öffnungspunkt des Austritts C der zweiten Entlastungsleitung 33 dargestellt. Diese Linie steigt entsprechend der mit der Last verstellbaren Stellung des Ringschiebers 24 mit zunehmender Last an. Weiterhin ist mit D der Aufsteuerpunkt des ersten Austritts D der ersten Entlastungsleitung 15 dargestellt. Diese Linie verläuft parallel zur Linie C und kennzeichnet den möglichen Nutzhub hn. Dieser Nutzhub ist in Figur 1 angegeben unter der Voraussetzung, daß der Pumpenkolben in der gezeigten Stellung seinen untersten Totpunkt einnimmt. Für den gezeigten Fall wurde eine gestrichelte Stellung des Ringschiebers 24 angenommen.Line C represents the opening point of the outlet C of the second relief line 33. This line rises with increasing load in accordance with the position of the ring slide 24 which is adjustable with the load. D also shows the opening point D of the first discharge line 15. This line runs parallel to line C and indicates the possible useful stroke h n . This useful stroke is indicated in FIG. 1 provided that the pump piston assumes its bottom dead center in the position shown. For the case shown, a broken position of the ring slide 24 was assumed.

Parallel zur Linie SB liegt eine Linie A, die den Aufsteuerpunkt des Eintritts A der zweiten Entlastungsleitung 33 kennzeichnet, Die dazu parallele Linie B gibt den Kolbenhub an, bei dem der zweite Austritt der ersten Entlastungsleitung geschlossen wird. In dem Hubbereich zwischen A und B, dem Hub he besteht die Verbindung zwischen der ersten Entlastungsleitung 15 und der zweiten Entlastungsleitung 33. Nur innerhalb dieses Hubbereiches kann der vom Pumpenkolben in diesem Bereich geförderte Kraftstoff oder ein Teil desselben über die zweite Entlastungsleitung 33 abströmen. Dies ist mit einer zweiten Bedingung jedoch nur möglich, wenn auch der Austritt C der zweiten Entlastungsleitung geöffnet ist, das heißt also, daß ab dem Schnittpunkt der Linie C mit der Linie B kein Abströmen von Kraftstoff mehr möglich ist. Dieser Punkt G liegt noch vor dem Vollastpunkt, so daß im oberen Lastbereich und bei Volllast das gesamte Arbeitsvermögen des Pumpenkolbens zur Kraftstofförderung ausgenutzt werden kann. Bei Nullast, im Leerlaufbereich oder bei niedriger Teillast liegt der Entlastungsbereich zwischen den Linien A und B innerhalb des Bereiches zwischen C und D, so daß über diesen Bereich zunächst eine konstante Kraftstoffmenge pro Förderhub des Pumpenkolbens abgesteuert wird, solange bis die Linie C die Linie A in dem Punkt F schneidet. Zwischen F und G wird die Etlastungsmenge zunehmend geringer. Die Lage des Bereiches he und seine Nutzhöhe können optimiert werden im Hinblick auf einen leisen Verbrennungsablauf bei niedriger Last und ohne Beeinflussung der Spritzbeginnsteuerung, die z. B. durch einen separaten Spritzbeginnversteller bekannter Bauart erfolgen kann.Parallel to line SB is a line A, which marks the opening point of the inlet A of the second relief line 33. The line B parallel thereto indicates the piston stroke at which the second outlet of the first relief line is closed. In the stroke range between A and B, the stroke h e, there is a connection between the first relief line 15 and the second relief line 33. Only within this stroke range can the fuel delivered by the pump piston in this area or a part thereof flow out via the second relief line 33. However, this is only possible with a second condition, if the outlet C of the second relief line is also open, that is to say that from the point of intersection of the line C with the line B, it is no longer possible for fuel to flow out. This point G is still before the full load point, so that the entire working capacity of the pump piston can be used for fuel delivery in the upper load range and at full load. At zero load, in the idling range or at low partial load, the relief range between lines A and B is within the range between C and D, so that a constant amount of fuel per delivery stroke of the pump piston is initially diverted over this range until line C leads to line A. intersects at point F. Between F and G the amount of relief becomes increasingly smaller. The location of the area h e and its usable height can be optimized with regard to a quiet combustion process at low load and without influencing the injection start control, which, for. B. can be done by a separate spray start adjuster of known design.

In Figur 3 ist eine andere Art der Vebindung zwischen der ersten Entlastungsleitung 15 und der zweiten Entlastungsleitung 33 in einem Teilabschnitt des Kolbens dargestellt. Hier weist die Ringnut 37 eine definierte Höhe he' auf, der Eintritt A' der zweiten Entlastungsleitung 33 ist in Hubrichtung verbreitert, so daß er ständig mit der Ringnut 37 in Verbindung bleibt und der zweite Austritt B' der ersten Entlastungsleitung 15 ist schlitzförmig gestaltet. Während des Förderhubes des Pumpenkolbens 4 bleibt also die zweite Entlastungsleitung 33 in ständiger Verbindung mit der Ringnut 37. Die Dauer der Verbindung zwischen der ersten Entlastungsleitung 15 und der zweiten Entlastungsleitung 33 wird nun durch den schlitzförmigen zweiten Austritt B' während der Überdeckung he mit der Ringnut 37 bestimmt.FIG. 3 shows another type of connection between the first relief line 15 and the second relief line 33 in a partial section of the piston. Here, the annular groove 37 has a defined height he ', the inlet A' of the second relief line 33 is widened in the stroke direction, so that it remains in constant communication with the annular groove 37 and the second outlet B 'of the first relief line 15 is designed in the form of a slot. During the delivery stroke of the pump piston 4, the second relief line 33 thus remains in constant connection with the annular groove 37. The duration of the connection between the first relief line 15 and the second relief line 33 is now determined by the slot-shaped second outlet B 'during the overlap h e with the Ring groove 37 determined.

Diese Ausgestaltung hat den Vorteil, daß die Steuerzeiten der Überdeckung hier genauer ausgestaltet werden können durch die schlitzartige Ausbildung des zweiten Austritts B' erfolgt eine schnelle Öffnung, wodurch der Drehzahleinfluß auf die Absteuermenge reduziert wird. Durch die schlitzartige Ausbildung kann ferner vorteilhaft ein Drosselquerschnitt bestimmt werden, der das Maß der Entlastung über den Rub he steuert.This embodiment has the advantage that the control times of the overlap can be made more precise here, because of the slot-like design of the second outlet B ', a rapid opening takes place, as a result of which the influence of the speed on the discharge quantity is reduced. Due to the slot-like design, a throttle cross-section can also advantageously be determined, which controls the degree of relief via the rub h e .

Figur 4 zeigt eine äquivalente Ausgestaltung zum Ausführungsbeispiel nach Figur 3. Dort ist nicht der zweite Austritt D sondern die Ringnut 37' schlitzförmig ausgebildet und es bestimmt die Breite des zweiten Austritts B der Größe hb die Dauer der Überdeckung he.FIG. 4 shows an equivalent configuration to the exemplary embodiment according to FIG. 3. There, it is not the second outlet D but the annular groove 37 ′ which is slot-shaped and the width of the second outlet B of size h b determines the duration of the overlap h e .

Ein viertes Ausführungsbeispiel der Verbindung zwischen der ersten Entlastungsleitung 15 und der zweiten Entlastungsleitung 33 stellt die Lösung nach Figur 5 dar. Dort ist in der Zylinderbüchse 3 ein Bypasskanal 39 vorgesehen, der sich achsparallel zur Achse des Pumpenkolbens erstreckt. Der Bypasskanal mündet in eine erste pumpenarbeitsraumseitige Ringnut 41 und an seinem anderen Ende in eine zweite Pumpensaugraumseitig gelegene Ringnut 42. Die Austrittslage des zweiten Austritts B der ersten Entlastungsleitung 15 und die Lage des Eintritts A der zweiten Entlastungsleitung 33 sind dabei so zugeordnet, daß nachdem der zweite Austritt B in Überdeckung mit der ersten Ringnut 41 gelangt ist, der Eintritt A nur noch über einen Hub he in Überdeckung mit der zweiten Ringnut 42 ist. Die Zuordnung kann natürlich auch im umgekehrten Sinne erfolgen. Wesentlich ist lediglich, daß der Überdeckungsbereich he eingehalten ist. Die Ringnuten 41 und 42 können auch in äquivalenter Weise am Pumpenkolben vorgesehen werden.A fourth exemplary embodiment of the connection between the first relief line 15 and the second relief line 33 is the solution according to FIG. 5. A bypass channel 39 is provided there in the cylinder liner 3 and extends parallel to the axis of the pump piston. The bypass channel opens into a first annular groove 41 on the pump work space and at its other end in a second annular groove 42 located on the pump suction chamber side second outlet B has overlapped with the first annular groove 41, the inlet A is only over one stroke h e overlapped with the second annular groove 42. The assignment can of course also be done in the opposite sense. It is only essential that the coverage area h e is observed. The annular grooves 41 and 42 can also be provided in an equivalent manner on the pump piston.

Statt dieser Lösung kann die Ausführung gemäß Figur 6 auch so erfolgen, daß der zweite Austritt B' der ersten Entlastungsleitung 15 wiederum schlitzförmig ausgestaltet ist und die pumpenarbeitsraumseitige Einmündung des Bypasskanals 39, ebenfalls in Form eines Schlitzes 44 gleicher Breite verwirklicht ist. Das andere Ende des Bypasskanals 39' ist dabei unabhängig vom Pumpenkolbenhub über den Eintritt A mit der zweiten Entlastungsleitung 33 verbunden. Bei dieser Ausführungsform bestimmt die Breite des Schlitzes B' bzw. 44 die Dauer der Überdeckung he.Instead of this solution, the embodiment according to FIG. 6 can also be carried out in such a way that the second outlet B 'of the first relief line 15 is again slit-shaped and the bypass duct 39 on the pump work chamber side, likewise in the form of a slot 44 of the same width, is realized. The other end of the bypass channel 39 'is connected to the second relief line 33 via the inlet A regardless of the pump piston stroke. In this embodiment, the width of the slot B 'or 44 determines the duration of the overlap h e .

Anhand des sechsten Ausführungsbeispiels nach Figur 7 wird gezeigt, daß die oben beschriebene Einrichtung zur Erzeugung eines leisen Laufes der Brennkraftmaschine bei Leerlauf und im Teillastbereich auch dann verwirklicht werden kann, wenn der Ringschieber 24" nicht das Ende der Förderung des Pumpenkolbens zu einem früheren oder späteren Punkt vor OT steuert, sondern den Beginn der Förderung des Pumpenkolbens nach einem mehr oder weniger großen Leerhub des Pumpenkolbens. Die Ausgestaltung der Kraftstoffeinspritzpumpe mit Pumpenkolben 4', Zylinder 2 und Ringschieber 24" ist dabei im wesentlichen gleich wie beim Ausführungsbeispiel nach Figur 1. Nur wird hier der Ringschieber in umgekehrter Logik von dem Reglerhebel 27 betätigt. Abweichend vom Ausführungsbeispiel nach Figur 1 ist der erste Austritt D" so angeordnet, daß er beim beginnenden Pumpenkolbenförderhub zuerst von der nun unten liegenden Steuerkante 25" verschlossen wird, bevor die Steuerkante 25" den nachfolgenden Austritt C" der zweiten Entlastungsleitung 33" zusteuert. Die konstruktive Hubdifferenz wird auch hier hy genannt in gleicher Weise wie beim Ausführungsbeispiel nach Figur 1 sind hier der Eintritt A" der zweiten Entlastungsleitung 33" und der zweite Austritt B" der ersten Entlastungsleitung 15" im Arbeitsbereich zur Ringnut 37 angeordnet.The sixth exemplary embodiment according to FIG. 7 shows that the device described above for generating a quiet running of the internal combustion engine at idle and in the partial load range can also be implemented when the ring slide 24 "does not mean the end of the delivery of the pump piston to an earlier or later one Point before TDC controls, but the beginning of the delivery of the pump piston after a more or less large idle stroke of the pump piston. The configuration of the fuel injection pump with pump piston 4 ', cylinder 2 and ring slide 24 "is essentially the same as in the exemplary embodiment according to FIG here the ring slide is operated in reverse logic by the control lever 27. In a departure from the exemplary embodiment according to FIG. 1, the first outlet D "is arranged in such a way that when the pump piston delivery stroke begins, it is first closed by the control edge 25" which is now below, before the control edge 25 "controls the subsequent outlet C" of the second relief line 33 " constructive stroke difference is also called hy here in the same way as in the exemplary embodiment according to FIG. 1, the inlet A "of the second relief line 33" and the second outlet B "of the first relief line 15" are arranged in the working area to the annular groove 37.

In Figur 8 ist ein der Figur 2 entsprechendes Diagramm für diesen Ausführungsfall dargestellt. Die Linie D" verläuft entsprechend der variablen Stellung des Ringschiebers 24" geneigt in Richtung Vollast VL. In gleicher Weise geneigt verläuft die Linie C", die den Schließpunkt des Austritts C" kennzeichnet, und zwar mit dem Abstand h" zur Schließpunktlinie des ersten Austrittsquerschnitts D". Mit FE ist eine parallel zur Abszisse verlaufende Linie gekennzeichnet, die das konstruktive Förderende des Pumpenkolbens kennzeichnet. Es sind weiterhin in dem Diagramm die Linie A" und die Linie B" als zur Linie FE parallele Linien dargestellt. A" kennzeichnet dabei den Punkt, bei dem der Eintritt A" in Verbindung mit der Ringnut 37 kommt, wo zugleich die Verbindung zwischen dem zweiten Austritt B" und der Ringnut 37 noch existiert und die Linie B" kennzeichnet den Punkt, bei dem der zweite Austritt B" verschlossen wird und die Verbindung zwischen der ersten Entlastungsleitung 15" und der zweiten Entlastungsleitung 33 unterbunden wird. Eine Reduzierung der resultierenden Einspritzrate bei Leerlauf und niedriger Last durch zeitweilig unterbrochenen oder verminderten Förderung ergibt sich auch bei dieser Ausführungsform einer Kraftstoffeinspritzpumpe. Abweichend gegenüber dem Ausführungsbeispiel nach Figur 1 ist hier jedoch die Voreinspritzmenge vor der Entlastung abhängig von der Last.FIG. 8 shows a diagram corresponding to FIG. 2 for this embodiment. The line D "runs according to the variable position of the ring slide 24" inclined towards full load VL. Tilted in the same way The line C ", which marks the closing point of the outlet C", runs with the distance h " to the closing point line of the first outlet cross section D". FE denotes a line running parallel to the abscissa, which indicates the constructive delivery end of the pump piston. Line A "and line B" are also shown in the diagram as lines parallel to line FE. A "denotes the point at which the inlet A" comes into contact with the annular groove 37, where at the same time the connection between the second outlet B "and the annular groove 37 still exists and the line B" denotes the point at which the second Exit B "is closed and the connection between the first relief line 15" and the second relief line 33 is prevented. A reduction in the resulting injection rate at idle and low load due to temporarily interrupted or reduced delivery also results in this embodiment of a fuel injection pump. Deviating from the exemplary embodiment according to FIG. 1, however, the pre-injection quantity before the relief is dependent on the load.

Claims (10)

1. Fuel injection pump for internal combustion engines with a pump piston (4), which reciprocates in a cylinder (2) and at the same time is rotatingly driven and during this process is used as a distributor and which encloses in the cylinder (2) a pump working space (5) which is continuously connected to a first relief line (15) which extends in the pump piston and which has a first outlet (D) on the surface area of the pump piston for connection to a relief space (7), which first outlet can be opened or closed at a point (25), which can be adjusted in dependence on load and/or rotatory speed, of the pump piston stroke path, with a second relief line (33) which is arranged in the pump piston and exhibits an inlet (A) and an outlet (C) on the pump piston surface area, in which arrangement a connection between the inlet (A) of the second relief line (33) and a second outlet (B) of the first relief line (15) is interrupted or established via a duct (37, 39) arranged in the wall of the cylinder (2) from a first, predetermined stroke of the pump piston and the outlet (C) of the second relief line (33) is opened or closed by the pump piston movement when it moves over a control edge (25), in which arrangement the closing of the outlet (C) of the second relief line occurs a constant predetermined part-stroke (hv) of the pump piston (4) after the closing of the first outlet (D) of the first relief line (15), which occurs at the adjustable point of the pump piston stroke path, and the opening of the second relief line occurs a predetermined part-stroke (hy) of the pump piston before the opening of the first outlet (D) of the first relief line (15), which occurs at the adjustable point of the pump piston stroke path, the inlet (A) of the second relief line (33) being connected to the first relief line over a predetermined stroke section (he) of the pump piston delivery stroke, characterized in that the inlet (A) of the second relief line (33) is connected to the first relief line (15) after a part of the pump piston delivery stroke over the predetermined stroke section (he) of the pump piston delivery stroke, the predetermined stroke section (he) being shorter than the predetermined part stroke (hy) and the predetermined stroke section being placed in such a manner that in the upper load range the outlet (C) of the second relief line (33) is only opened after the connection between the first relief line (15) and the second relief line (33) has been interrupted or the outlet (C") of the second relief line (33") is already closed before the connection has been established between the first relief line (15") and the second relief line (33").
2. Fuel injection pump according to Claim 1, characterized in that the duct is an annular groove (37).
3. Fuel injection pump according to Claim 2, characterized in that the second outlet (B) of the first relief line (15) or the inlet (A) of the second relief line (33) are in stroke-independent connection with the annular groove (37) and the width of the corresponding other connect ion cross-section, which can be connected to the annular groove and which is located in the axial direction of the pump piston (4), of the inlet (A) of the second relief line (33) or of the second outlet (B) of the first relief line (15) together with the height, which extends in the axial direction of the pump piston (4), of the annular groove (37) form the elements determining the predetermined stroke section (he).
4. Fuel injection pump according to Claim 3, characterized in that the height deviates significantly from the width, in particular the height is great compared with the width.
5. Fuel injection pump according to Claim 1, characterized in that the duct is constructed as a bypass duct (39, 39') which extends in the axial direction and opens at both ends into the cylinder (2).
6. Fuel injection pump according to Claim 5, characterized in that the second outlet (B) of the first relief line (15) or the inlet (A) of the second relief line (33) are connected to the duct (39) independently of the stroke, and the width, which is located in the axial direction of the pump piston (4), of the corresponding other connection cross-section which can be connected to the duct, of the inlet (A) of the second relief line (33) or of the outlet (B) of the first relief line (15) together with the height, which extends in the axial direction of the pump piston (4), of the cross-section of the opening of the other end of the bypass duct (39) into the cylinder (2) form the elements determining the predetermined stroke section (he).
7. Fuel injection pump according to Claim 6, characterized in that the height significantly deviates from the width, in particular the height is great compared with the width.
8. Fuel injection pump according to Claim 6, characterized in that the height and the width are of equal size and small compared with the width of the second outlet (B), forming the stroke-independent connection, of the first relief line (15) or of the inlet (A) of the second relief line (33)
9. Fuel injection pump according to one of the preceding Claims, characterized in that the outlet (C) of the second relief line (33) and the first outlet (D) of the first relief line (15) open at an end, which protrudes from the cylinder (2), of the pump piston (4) and are there controlled by a control edge (25) which is arranged on a valve member (24) which can be displaced closely on the pump piston in dependence on load and/or rotary speed for adjusting the said adjustable point of the pump piston stroke path.
10. Fuel injection pump according to one of the preceding Claims, characterized in that a throttle cross-section B' is effective when the connection between the first relief line and the second relief line is opened.
EP85106902A 1984-07-06 1985-06-04 Fuel injection pump for internal-combustion engines Expired EP0166995B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843424883 DE3424883A1 (en) 1984-07-06 1984-07-06 FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES
DE3424883 1984-07-06

Publications (3)

Publication Number Publication Date
EP0166995A2 EP0166995A2 (en) 1986-01-08
EP0166995A3 EP0166995A3 (en) 1987-06-16
EP0166995B1 true EP0166995B1 (en) 1989-03-08

Family

ID=6239970

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Application Number Title Priority Date Filing Date
EP85106902A Expired EP0166995B1 (en) 1984-07-06 1985-06-04 Fuel injection pump for internal-combustion engines

Country Status (4)

Country Link
US (1) US4635605A (en)
EP (1) EP0166995B1 (en)
JP (1) JPS6131628A (en)
DE (2) DE3424883A1 (en)

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DE3612068A1 (en) * 1986-04-10 1987-10-15 Bosch Gmbh Robert FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES WITH EXHAUST GAS RECIRCULATION
DE3644147A1 (en) * 1986-12-23 1988-07-07 Bosch Gmbh Robert FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES
DE3644583A1 (en) * 1986-12-27 1988-07-07 Bosch Gmbh Robert FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES
EP0308988A1 (en) * 1987-09-25 1989-03-29 Sidelsky, Michael Stewart Control module
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WO2015051784A2 (en) 2013-10-08 2015-04-16 4-QM hydraulics GmbH Turbomachine

Also Published As

Publication number Publication date
EP0166995A3 (en) 1987-06-16
DE3568608D1 (en) 1989-04-13
US4635605A (en) 1987-01-13
EP0166995A2 (en) 1986-01-08
JPH0577856B2 (en) 1993-10-27
JPS6131628A (en) 1986-02-14
DE3424883A1 (en) 1986-02-06

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