EP1606511A1 - Fuel injection device for a combustion engine - Google Patents

Fuel injection device for a combustion engine

Info

Publication number
EP1606511A1
EP1606511A1 EP03815794A EP03815794A EP1606511A1 EP 1606511 A1 EP1606511 A1 EP 1606511A1 EP 03815794 A EP03815794 A EP 03815794A EP 03815794 A EP03815794 A EP 03815794A EP 1606511 A1 EP1606511 A1 EP 1606511A1
Authority
EP
European Patent Office
Prior art keywords
pressure
spring
chamber
fuel injection
fuel
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.)
Granted
Application number
EP03815794A
Other languages
German (de)
French (fr)
Other versions
EP1606511B1 (en
Inventor
Gérard Duplat
Raphael Pourret
Alain Amblard
Raphael Combe
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
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1606511A1 publication Critical patent/EP1606511A1/en
Application granted granted Critical
Publication of EP1606511B1 publication Critical patent/EP1606511B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

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
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
    • F02M61/20—Closing valves mechanically, e.g. arrangements of springs or weights or permanent magnets; Damping of valve lift
    • F02M61/205—Means specially adapted for varying the spring tension or assisting the spring force to close the injection-valve, e.g. with damping of valve lift
    • 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
    • F02M45/08—Injectors 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
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/002—Arrangement of leakage or drain conduits in or from injectors
    • 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
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/04—Means for damping vibrations or pressure fluctuations in injection pump inlets or outlets
    • 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
    • F02M57/00—Fuel-injectors combined or associated with other devices
    • F02M57/02—Injectors structurally combined with fuel-injection pumps
    • F02M57/022—Injectors structurally combined with fuel-injection pumps characterised by the pump drive
    • F02M57/023—Injectors structurally combined with fuel-injection pumps characterised by the pump drive mechanical
    • 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
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/0012—Valves
    • F02M63/0014—Valves characterised by the valve actuating means
    • F02M63/0015—Valves characterised by the valve actuating means electrical, e.g. using solenoid
    • 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
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/0012—Valves
    • F02M63/0031—Valves characterized by the type of valves, e.g. special valve member details, valve seat details, valve housing details
    • F02M63/004—Sliding valves, e.g. spool valves, i.e. whereby the closing member has a sliding movement along a seat for opening and closing
    • 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
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/0012—Valves
    • F02M63/0031—Valves characterized by the type of valves, e.g. special valve member details, valve seat details, valve housing details
    • F02M63/0043—Two-way valves
    • 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
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/31—Fuel-injection apparatus having hydraulic pressure fluctuations damping elements
    • F02M2200/315—Fuel-injection apparatus having hydraulic pressure fluctuations damping elements for damping fuel pressure fluctuations

Definitions

  • the invention is based on one
  • Fuel injection device for an internal combustion engine according to the preamble of claim 1.
  • Such a fuel injection device is known from DE 198 44 891 A.
  • This fuel injection device has a high-pressure fuel pump and a fuel injection valve for a cylinder of the internal combustion engine.
  • the high-pressure fuel pump has a pump piston which is driven by the internal combustion engine and delimits a pump work space, a connection of the pump work space to a relief region being controlled by an electrically controlled valve.
  • the fuel injection valve has an injection valve member, through which at least one injection opening is controlled and which can be moved in an opening direction against the force of a closing spring arranged in a spring chamber by the pressure prevailing in a pressure chamber having a connection to the pump working chamber.
  • the closing spring is supported on the one hand at least indirectly on the injection valve member and on the other hand at least indirectly on a storage piston.
  • the storage piston delimits a storage space on its side facing away from the closing spring, which has a connection to the pump working space and can be moved into the spring space against the force of the closing spring.
  • the spring chamber has a connection to a low-pressure area via a throttle point, the low-pressure area being connected to a fuel inlet.
  • the accumulator piston enables fuel to be pre-injected by moving it into the spring chamber as the pressure in the pump working chamber rises due to the pressure prevailing in the storage chamber. When the pressure in the pump work chamber and thus in the pressure chamber of the fuel injector increases, its injector member first opens for the pre-injection.
  • the amount of fuel that is injected during the pre-injection is predetermined in a map as a function of the operating parameters of the internal combustion engine, in particular the speed. It was found that the amount of fuel injected during the pre-injection is significantly influenced by pressure fluctuations in the spring chamber, which in turn are caused by pressure fluctuations in the low pressure range.
  • the fuel injection device according to the invention with the features according to claim 1 has the advantage, that pressure fluctuations in the spring chamber are reduced due to the connection of the spring chamber with the low-pressure region of great length, and thus the fuel injection quantity during the pre-injection can be maintained more precisely.
  • advantageous refinements and developments of the fuel injection device according to the invention are specified.
  • the design according to claims 2 to 4 enables a large length of the channel connecting the spring chamber with the low pressure area.
  • FIG. 3 A fuel injector in a second longitudinal section and FIG. 3 the fuel injector in a cross section along line III-III in FIG. 1.
  • Fuel injection device for an internal combustion engine of a motor vehicle shown.
  • the internal combustion engine has one or more cylinders, a fuel injection device having a high-pressure fuel pump 10 and a fuel injection valve 12 being provided for each cylinder.
  • Fuel injection valve 12 are combined to form a so-called pump-nozzle unit.
  • the high-pressure fuel pump 10 has a pump body 14, in which a pump piston 18 is tightly guided in a cylinder 16 and is driven by a cam 20 of a camshaft of the internal combustion engine against the force of a return spring 19 in a stroke movement.
  • the pump piston 18 delimits a pump working chamber 22 in the cylinder 16, in which fuel is compressed under high pressure during the delivery stroke of the pump piston 18.
  • fuel is supplied to the pump work chamber 22 from a fuel storage tank 24, for example by means of a feed pump 21.
  • the pump work room 22 has a connection to a relief region, which can serve, for example, as a return to the fuel storage tank 24, and which is operated by an electrically operated one Control valve 23 is controlled.
  • the control valve 23 is connected to an electronic control device 25.
  • the fuel injection valve 12 has a valve body 26, which can be constructed in several parts, and which is connected to the pump body 14, for example with the interposition of at least one intermediate body 27.
  • a disk 15 can also be arranged between the intermediate body 27 and the pump body 14.
  • An injection valve member 28 is guided in a longitudinally displaceable manner in a bore 30 in the valve body 26.
  • the bore 30 runs at least approximately parallel to the cylinder 16 of the pump body 14, but can also run at an incline to the latter.
  • the valve body 26 has at least one, preferably a plurality of injection openings 32 at its end region facing the combustion chamber of the cylinder of the internal combustion engine.
  • the injection valve member 28 has at its end region facing the combustion chamber an, for example, approximately conical sealing surface 34 which interacts with a valve seat 36, for example likewise approximately conical in the valve body 26 in its end region facing the combustion chamber, from or after which the injection openings 32 lead away.
  • a valve seat 36 for example likewise approximately conical in the valve body 26 in its end region facing the combustion chamber, from or after which the injection openings 32 lead away.
  • annular space 38 between the injection valve member 28 and the bore 30 towards the valve seat 36, which in its end region facing away from the valve seat 36 passes through a radial expansion of the bore 30 into a pressure chamber 40 surrounding the injection valve member 28.
  • the injection valve member 28 has a pressure shoulder 42 facing the valve seat 36 at the level of the pressure chamber 40 due to a reduction in cross section.
  • a prestressed closing spring 44 engages, by means of which the injection valve member 28 is pressed toward the valve seat 36.
  • the closing spring 44 is arranged in a spring chamber 46, formed by a bore 47, of a spring holding body 45, which forms part of the valve body 26 and which adjoins the bore 30.
  • One or more disks 43 can be arranged between the valve body 26 and the spring holding body 45.
  • the pressure chamber 40 has a connection 48 to the pump working chamber 22 which extends through the valve body 26, the disks 43, the spring holding body 45, the intermediate body 27, the disk 15 and the pump body 14.
  • the closing spring 44 is supported on the one hand at least indirectly, for example via a spring plate, on the injection valve member 28 and on the other hand at least indirectly, for example likewise via a spring plate, on a storage piston 50.
  • the storage piston 50 is guided in a bore 51 in the intermediate body 27, which is coaxial with the spring space 46, and delimits a storage space 52 in the bore 51 with its end face remote from the closing spring 44.
  • the storage space 52 has a disk 15 through the intermediate body 27 and connection 54 running the pump body 14 to the pump working space 22.
  • the valve body 26 and the pump body 14 are connected and clamped to one another by means of a clamping nut 60 with the spring holding body 45, the intermediate body 27 and the disk 15 being interposed.
  • the clamping nut 60 engages over the valve body 26 and is screwed onto an external thread formed on the pump body 14.
  • An annular space 62 is formed between the clamping nut 60 and the valve body 26 at the level of the pressure chamber 40 and the bore 30 in which the injection valve member 28 is tightly guided.
  • the clamping nut 60 has a multiplicity of openings 64, each with a small cross section, which form filter openings.
  • the clamping nut 60 is surrounded on the outside in the region of the annular space 62 by a further annular space 66 which is formed between the clamping nut 60 and a bore 68 in a cylinder head of the internal combustion engine, into which the fuel injection device is inserted.
  • a fuel inlet from the feed pump 21 opens into the annular space 66.
  • the fuel supplied by the feed pump 21 passes through the filter openings 64 into the annular space 62 and out of this via channels 70 in the disks 43, in the spring holding body 45, in the intermediate body 27, in the disk 50 and in the pump body 14 into a valve space 72 of the control valve 23 Depending on the switching position, the valve chamber 72 can be connected to the pump working chamber 22 and separated from the pump working chamber 22 by a control valve member 74.
  • the valve chamber 72 also has a connection with a return to the fuel reservoir 24.
  • the annular space 62 forms a low-pressure area to which the spring space 46 is connected.
  • a channel 76 for example in the form of a bore, is formed in the spring holding body 45 and extends along the spring chamber 46.
  • the channel 76 continues through the disks 43 and opens into the annular space 62.
  • the channel 76 ends on the other hand on the intermediate body 27.
  • the spring chamber 46 is connected to the channel 76 via a throttle point 78 which is arranged near the end of the spring chamber 46 facing the accumulator piston 50.
  • the channel 76 thus extends from the end region of the spring chamber 46 facing the storage piston 50 to the annular chamber 62 and has a great length.
  • the low-pressure region 62 is arranged at a distance from the spring chamber 46 in the direction of the longitudinal axis 13 of the fuel injection valve 12.
  • the spring chamber 46 is thus connected via the long channel 76 to the annular space 62 forming the low-pressure region, the channel 76 forming a damping chamber in which pressure fluctuations in the annular chamber 62 are weakened, so that these lead to only slight pressure fluctuations in the spring chamber 46.
  • the function of the fuel injection device is explained below.
  • the pump working chamber 22 is filled with fuel during the suction stroke of the pump piston 18 with the control valve 23 open.
  • the fuel delivered by the feed pump 21 enters the annular space 66, passes through the filter openings 64 into the annular space 62 and flows out of this via the channels 70 into the valve space 72 and out of this into the pump work space 22.
  • the control valve 23 is initially opened, so that no high pressure can build up in the pump work chamber 22.
  • the control valve 23 is closed by the control device 25, so that the pump working chamber 22 is separated from the valve chamber 72 and thus from the fuel inlet and the return to the fuel reservoir 24 and builds up in this high pressure.
  • the injection valve member 28 moves in the opening direction 29 and opens the at least one injection opening 32, through which fuel is injected into the combustion chamber of the cylinder.
  • the storage piston 50 is in a starting position in which it is arranged closest to the disk 15. The pressure in the pump work chamber 22 subsequently increases further in accordance with the profile of the cam 20.
  • the accumulator piston 50 executes an evasive stroke movement and moves away from the disk 15 into the spring chamber 46 into it, with the storage space 52 being enlarged.
  • This causes an increase in pressure in the spring chamber 46, since fuel can flow out of it only with a delay because of the throttle point 78, and also increases the pretension of the closing spring 44, which is supported on the accumulator piston 50.
  • the pressure prevailing in the spring chamber 46 generates, via the spring plate, by means of which the closing spring 44 is supported on the injection valve member 28, a force acting on the injection valve member 28 in the closing direction.
  • the pressure increase in the spring chamber 46 and the increase in the pretension of the closing spring 44 result in an increased force in the closing direction on the injection valve member 28, so that it is moved again in the closing direction, comes into contact with its sealing surface 34 on the valve seat 36 and closes the injection openings 32 so that fuel injection is stopped.
  • the fuel injection valve 12 is only open for a short period of time and only a small amount of fuel is injected into the combustion chamber as a pre-injection. The amount of fuel injected depends, among other things, on the pressure prevailing in the spring chamber 46, which, as stated above, generates a force acting in the closing direction on the injection valve member 28.
  • the opening stroke of the injection valve member 28 during the pre-injection can be hydraulically limited by a damping device.
  • the injection valve member 28 dips with a pressure pin 80 into a fuel-filled damping space 82, which is delimited by a fixed shoulder 84 formed by an end face of the disk 43, which forms a stroke stop for an annular shoulder 86 on the injection valve member 28.
  • a throttle cross section is formed between the wall of the damping chamber 82 and the pressure pin 80, which is designed as a ground section 88 and via which the damping chamber 82 is connected to the spring chamber 46.
  • the surface grinding 88 on the pressure pin 80 is axially spaced from the annular shoulder 86 on the injection valve member 28, in the area of which the pressure pin 80 corresponds to the diameter of the bore in the disk 43, so that a control edge 90 is formed, the traversing of which via the shoulder 84 controls the control of the hydraulic damping chamber 82 controls.
  • Pre-injection runs through the injection valve member 28 only a partial opening stroke, which is limited by driving over the control edge 90 on the injection valve member 28 via the shoulder 84 of the disk 43, as a result of which the damping chamber 82 is closed, so that the closing force on the injection valve member 28 increases.
  • the pressure in the pump work chamber 22 subsequently increases further in accordance with the profile of the cam 20, so that the pressure force acting on the injection valve member 28 increases again in the opening direction 29 and exceeds the increased closing force as a result of the increased preload of the closing spring 44 and the increased pressure in the spring chamber 46, so that the fuel injection valve 12 opens again.
  • a larger amount of fuel is injected over a longer period of time than during the pre-injection.
  • the time period and the amount of fuel injected during this main injection are determined by the point in time at which the control valve 23 is opened again by the control device 25.
  • the pump work chamber 22 is connected again to the return to the fuel reservoir 24, so that it is relieved and the fuel injection valve 12 closes.
  • the storage piston 50 is moved back into its starting position by the force of the closing spring 44.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fuel-Injection Apparatus (AREA)

Abstract

The fuel injection device comprises a fuel high-pressure pump (10) and a fuel injection valve (12) for a cylinder of a combustion engine. The fuel high-pressure pump (10) has a pump working space (22), and the fuel injection valve (12) has an injection valve element (38) via which at least one injection opening (32) is controlled and which can be moved in a direction of opening (29) against the force of a closing spring (44) by the pressure prevailing inside a pressure space (40) having a connection (48) to the pump working space (22). The closing spring (44) is supported on the injection valve element (28) and on a displaceable accumulator plunger (50) which, via its side facing away from the closing spring (44), delimits an accumulator space (52) having a connection (54) to the pump working space (22) and which can be displaced against the force of the closing spring (44) and into a spring space (46). The spring space (46) has a connection, which is formed by a channel (76), to a low-pressure area (62) extending along the spring space (46). Said spring space (46) is connected to an end area of the channel (76) via a throttling point (78), and the channel (76), at the opposite end thereof, leads into the low-pressure area (62).

Description

Kraftstoffeinspritzeinrichtung für eine BrennkraftmaschineFuel injection device for an internal combustion engine
Stand der TechnikState of the art
Die Erfindung geht aus von einerThe invention is based on one
Kraftstoffeinspritzeinrichtung für eine Brennkraftmaschine nach der Gattung des Anspruchs 1.Fuel injection device for an internal combustion engine according to the preamble of claim 1.
Eine solche Kraftstoffeinspritzeinrichtung ist durch die DE 198 44 891 A bekannt. Diese Kraftstoffeinspritzeinrichtung weist eine Kraftstoffhochdruckpumpe und ein Kraftstoffeinspritzventil für einen Zylinder der Brennkraftmaschine auf. Die Kraftstoffhochdruckpumpe weist einen durch die Brennkraftmaschine angetriebenen,, einen Pumpenarbeitsraum begrenzenden Pumpenkolben auf, wobei durch ein elektrisch gesteuertes Ventil eine Verbindung des Pumpenarbeitsraums mit einem Entlastungsbereich gesteuert wird. Das Kraftstoffeinspritzventil weist ein Einspritzventilglied auf, durch das wenigstens eine Einspritzöffnung gesteuert wird und das durch den in einem eine Verbindung mit dem Pumpenarbeitsraum aufweisenden Druckraum herrschenden Druck gegen die Kraft einer in einem Federraum angeordneten Schließfeder in einer Öffnungsrichtung bewegbar ist. Die Schließfeder stützt sich einerseits zumindest mittelbar am Einspritzventilglied und andererseits zumindest mittelbar an einem Speicherkolben ab. Der Speicherkolben begrenzt auf seiner der Schließfeder abgewandten Seite einen Speicherraum, der eine Verbindung mit dem Pumpenarbeitsraum aufweist und ist gegen die Kraft der Schließfeder in den Federraum bewegbar. Der Federraum weist über eine Drosselstelle eine Verbindung mit einem Niederdruckbereich auf, wobei der Niederdruckbereich mit einem KraftstoffZulauf verbunden ist. Der Speicherkolben ermöglicht eine Voreinspritzung von Kraftstoff, indem dieser bei ansteigendem Druck im Pumpenarbeitsraum durch den im Speicherraum herrschenden Druck in den Federraum bewegt wird. Bei steigendem Druck im Pumpenarbeitsraum und damit im Druckraum des Kraftstoffeinspritzventils öffnet dessen Einspritzventilglied zunächst für die Voreinspritzung. Bei der Bewegung des Speicherkolbens in den Federraum wird die Vorspannung der Schließfeder und der im Federraum herrschende Druck erhöht, so daß das Einspritzventilglied wieder schließt. Bei weiterem Druckanstieg im Pumpenarbeitsraum und im Druckraum öffnet das Einspritzventilglied gegen die erhöhte Vorspannung der Schließfeder und es erfolgt eine Haupteinspritzung von Kraftstoff. Die Kraftstoffmenge, die bei der Voreinspritzung eingespritzt wird, ist in einem Kennfeld abhängig von Betriebsparametern der Brennkraftmaschine, insbesondere der Drehzahl, vorgegeben. Es wurde festgestellt, daß die Kraftstoffeinspritzmenge bei der Voreinspritzung dabei wesentlich von Druckschwankungen im Federraum beeinflußt wird, die wiederum durch Druckschwankungen im Niederdruckbereich verursacht werden. Diese Druckschwankungen werden durch Schwankungen im Zulaufdruck und durch den Schließvorgang des Steuerventils ausgelöst, wenn der Pumpenarbeitsraum vom Entlastungsbereich getrennt wird. Da die Verbindung des Federraums mit dem Niederdruckbereich sehr kurz ist und direkt in den Niederdruckbereich mündet, werden die Druckschwankungen im Niederdruckbereich nahezu unvermindert in den Federraum übertragen. Durch die Druckschwankungen im Federraum wird es erschwert bei der Voreinspritzung die im Kennfeld vorgegebene Kraftstoffeinspritzmenge zu erreichen.Such a fuel injection device is known from DE 198 44 891 A. This fuel injection device has a high-pressure fuel pump and a fuel injection valve for a cylinder of the internal combustion engine. The high-pressure fuel pump has a pump piston which is driven by the internal combustion engine and delimits a pump work space, a connection of the pump work space to a relief region being controlled by an electrically controlled valve. The fuel injection valve has an injection valve member, through which at least one injection opening is controlled and which can be moved in an opening direction against the force of a closing spring arranged in a spring chamber by the pressure prevailing in a pressure chamber having a connection to the pump working chamber. The closing spring is supported on the one hand at least indirectly on the injection valve member and on the other hand at least indirectly on a storage piston. The storage piston delimits a storage space on its side facing away from the closing spring, which has a connection to the pump working space and can be moved into the spring space against the force of the closing spring. The spring chamber has a connection to a low-pressure area via a throttle point, the low-pressure area being connected to a fuel inlet. The accumulator piston enables fuel to be pre-injected by moving it into the spring chamber as the pressure in the pump working chamber rises due to the pressure prevailing in the storage chamber. When the pressure in the pump work chamber and thus in the pressure chamber of the fuel injector increases, its injector member first opens for the pre-injection. When the accumulator piston moves into the spring chamber, the bias of the closing spring and the pressure prevailing in the spring chamber are increased, so that the injection valve member closes again. If the pressure in the pump work chamber and in the pressure chamber continues to rise, the injection valve member opens against the increased pretension of the closing spring and a main injection of fuel takes place. The amount of fuel that is injected during the pre-injection is predetermined in a map as a function of the operating parameters of the internal combustion engine, in particular the speed. It was found that the amount of fuel injected during the pre-injection is significantly influenced by pressure fluctuations in the spring chamber, which in turn are caused by pressure fluctuations in the low pressure range. These pressure fluctuations are triggered by fluctuations in the inlet pressure and by the closing process of the control valve when the pump work space is separated from the relief area. Since the connection between the spring chamber and the low-pressure area is very short and opens directly into the low-pressure area, the pressure fluctuations in the low-pressure area are transmitted almost undiminished into the spring area. The pressure fluctuations in the spring chamber make it difficult to achieve the fuel injection quantity specified in the map during the pre-injection.
Vorteile der ErfindungAdvantages of the invention
Die erfindungsgemäße Kraftstoffeinspritzeinrichtung mit den Merkmalen gemäß Anspruch 1 hat demgegenüber den Vorteil, dass Druckschwankungen im Federraum durch die Verbindung des Federraums mit dem Niederdruckbereich mit großer Länge verringert sind und damit die Kraftstoffeinspritzmenge bei der Voreinspritzung genauer eingehalten werden kann. i In den abhängigen Ansprüchen sind vorteilhafte Ausgestaltungen und Weiterbildungen der erfindungsgemäßen Kraftstoffeinspritzeinrichtung angegeben. Die Ausbildung gemäß den Ansprüchen 2 bis 4 ermöglicht eine große Länge des Kanals der Verbindung des Federraums mit dem Niederdruckbereic .The fuel injection device according to the invention with the features according to claim 1 has the advantage, that pressure fluctuations in the spring chamber are reduced due to the connection of the spring chamber with the low-pressure region of great length, and thus the fuel injection quantity during the pre-injection can be maintained more precisely. i In the dependent claims, advantageous refinements and developments of the fuel injection device according to the invention are specified. The design according to claims 2 to 4 enables a large length of the channel connecting the spring chamber with the low pressure area.
Zeichnungdrawing
Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 eineAn embodiment of the invention is shown in the drawing and explained in more detail in the following description. 1 shows a
Kraftstoffeinspritzeinrichtung für eine Brennkraftmaschine in einem ersten Längsschnitt, Figur % dieFuel injection device for an internal combustion engine in a first longitudinal section, Figure% die
Kraftstoffeinspritzeinrichtung in einem zweiten Längsschnitt und Figur 3 die Kraftstoffeinspritzeinrichtung in einem Querschnitt entlang Linie III-III in Figur 1.A fuel injector in a second longitudinal section and FIG. 3 the fuel injector in a cross section along line III-III in FIG. 1.
Beschreibung des AusführungsbeispielsDescription of the embodiment
In den Figuren 1 bis 3 ist eineIn Figures 1 to 3 is one
Kraftstoffeinspritzeinrichtung für eine Brennkraftmaschine eines Kraftfahrzeugs dargestellt. Die Brennkraftmaschine weist einen oder mehrere Zylinder auf, wobei für jeden Zylinder eine Kraftstoffeinspritzeinrichtung mit einer Kraftstoffhochdruckpumpe 10 und einem Kraftstoffeinspritzventil 12 vorgesehen ist. Die Kraftstoffhochdruckpumpe 10 und dasFuel injection device for an internal combustion engine of a motor vehicle shown. The internal combustion engine has one or more cylinders, a fuel injection device having a high-pressure fuel pump 10 and a fuel injection valve 12 being provided for each cylinder. The high pressure fuel pump 10 and that
Kraftstoffeinspritzventil 12 sind zu einer sogenannten Pumpe-Düse-Einheit zusammengefaßt. Die Kraftstoffhochdruckpumpe 10 weist einen Pumpenkörper 14 auf, in dem in einem Zylinder 16 ein Pumpenkolben 18 dicht geführt ist, der durch einen Nocken 20 einer Nockenwelle der Brennkraftmaschine entgegen der Kraft einer Rückstellfeder 19 in einer Hubbewegung angetrieben wird. Der Pumpenkolben 18 begrenzt im Zylinder 16 einen Pumpenarbeitsraum 22, in dem beim Förderhub des Pumpenkolbens 18 Kraftstoff unter Hochdruck verdichtet wird. Dem Pumpenarbeitsraum 22 wird beim Saughub des Pumpenkolbens 18 Kraftstoff aus einem Kraftstoffvorratsbehälter 24 zugeführt, beispielsweise mittels einer Förderpumpe 21. Der Pumpenarbeitsraum 22 weist eine Verbindung mit einem Entlastungsbereich auf, als der beispielsweise ein Rücklauf zum Kraftstoffvorratsbehälter 24 dienen kann, und die von einem elektrisch betätigten Steuerventil 23 gesteuert wird. Das Steuerventil 23 ist mit einer elektronischen Steuereinrichtung 25 verbunden.Fuel injection valve 12 are combined to form a so-called pump-nozzle unit. The high-pressure fuel pump 10 has a pump body 14, in which a pump piston 18 is tightly guided in a cylinder 16 and is driven by a cam 20 of a camshaft of the internal combustion engine against the force of a return spring 19 in a stroke movement. The pump piston 18 delimits a pump working chamber 22 in the cylinder 16, in which fuel is compressed under high pressure during the delivery stroke of the pump piston 18. During the suction stroke of the pump piston 18, fuel is supplied to the pump work chamber 22 from a fuel storage tank 24, for example by means of a feed pump 21. The pump work room 22 has a connection to a relief region, which can serve, for example, as a return to the fuel storage tank 24, and which is operated by an electrically operated one Control valve 23 is controlled. The control valve 23 is connected to an electronic control device 25.
Das Kraftstoffeinspritzventil 12 weist einen Ventilkörper 26 auf, der mehrteilig ausgebildet sein kann, und der mit dem Pumpenkörper 14, beispielsweise unter Zwischenlage wenigstens eines Zwischenkörpers 27, verbunden ist. Zwischen dem Zwischenkörper 27 und dem Pumpenkörper 14 kann noch eine Scheibe 15 angeordnet sein. Im Ventilkörper 26 ist in einer Bohrung 30 ein Einspritzventilglied 28 längsverschiebbar geführt. Die Bohrung 30 verläuft zumindest annähernd parallel zum Zylinder 16 des Pumpenkörpers 14, kann jedoch auch geneigt zu diesem verlaufen. Der Ventilkörper 26 weist an seinem dem Brennraum des Zylinders der Brennkraftmaschine zugewandten Endbereich wenigstens eine, vorzugsweise mehrere Einspritzöffnungen 32 auf. Das Einspritzventilglied 28 weist an seinem dem Brennraum zugewandten Endbereich eine beispielsweise etwa kegelförmige Dichtfläche 34 auf, die mit einem im Ventilkörper 26 in dessen dem Brennraum zugewandtem Endbereich ausgebildeten, beispielsweise ebenfalls etwa kegelförmigen Ventilsitz 36 zusammenwirkt, von dem oder nach dem die Einspritzöffnungen 32 abführen. Im Ventilkörper 26 ist zwischen dem Einspritzventilglied 28 und der Bohrung 30 zum Ventilsitz 36 hin ein Ringraum 38 vorhanden, der in seinem dem Ventilsitz 36 abgewandten Endbereich durch eine radiale Erweiterung der Bohrung 30 in einen das Einspritzventilglied 28 umgebenden Druckraum 40 übergeht. Das Einspritzventilglied 28 weist auf Höhe des Druckraums 40 durch eine Querschnittsverringerung eine zum Ventilsitz 36 weisende Druckschulter 42 auf. Am dem Brennraum abgewandten Ende des Einspritzventilglieds 28 greift eine vorgespannte Schließfeder 44 an, durch die das Einspritzventilglied 28 zum Ventilsitz 36 hin gedrückt wird. Die Schließfeder 44 ist in einem durch eine Bohrung 47 gebildeten Federraum 46 eines Federhaltekörpers 45 angeordnet, der einen Teil des Ventilkörpers 26 bildet und der sich an die Bohrung 30 anschließt. Zwischen dem Ventilkörper 26 und dem Federhaltekörper 45 können ein oder mehrere Scheiben 43 angeordnet sein. Der Druckraum 40 weist wie in Figur 2 dargestellt eine durch den Ventilkörper 26, die Scheiben 43, den Federhaltekörper 45, den Zwischenkörper 27, die Scheibe 15 und den Pumpenkörper 14 verlaufende Verbindung 48 mit dem Pumpenarbeitsraum 22 auf.The fuel injection valve 12 has a valve body 26, which can be constructed in several parts, and which is connected to the pump body 14, for example with the interposition of at least one intermediate body 27. A disk 15 can also be arranged between the intermediate body 27 and the pump body 14. An injection valve member 28 is guided in a longitudinally displaceable manner in a bore 30 in the valve body 26. The bore 30 runs at least approximately parallel to the cylinder 16 of the pump body 14, but can also run at an incline to the latter. The valve body 26 has at least one, preferably a plurality of injection openings 32 at its end region facing the combustion chamber of the cylinder of the internal combustion engine. The injection valve member 28 has at its end region facing the combustion chamber an, for example, approximately conical sealing surface 34 which interacts with a valve seat 36, for example likewise approximately conical in the valve body 26 in its end region facing the combustion chamber, from or after which the injection openings 32 lead away. In the valve body 26 there is an annular space 38 between the injection valve member 28 and the bore 30 towards the valve seat 36, which in its end region facing away from the valve seat 36 passes through a radial expansion of the bore 30 into a pressure chamber 40 surrounding the injection valve member 28. The injection valve member 28 has a pressure shoulder 42 facing the valve seat 36 at the level of the pressure chamber 40 due to a reduction in cross section. At the end of the injection valve member 28 facing away from the combustion chamber, a prestressed closing spring 44 engages, by means of which the injection valve member 28 is pressed toward the valve seat 36. The closing spring 44 is arranged in a spring chamber 46, formed by a bore 47, of a spring holding body 45, which forms part of the valve body 26 and which adjoins the bore 30. One or more disks 43 can be arranged between the valve body 26 and the spring holding body 45. As shown in FIG. 2, the pressure chamber 40 has a connection 48 to the pump working chamber 22 which extends through the valve body 26, the disks 43, the spring holding body 45, the intermediate body 27, the disk 15 and the pump body 14.
Die Schließfeder 44 stützt sich einerseits zumindest mittelbar, beispielsweise über einen Federteller, am Einspritzventilglied 28 und andererseits zumindest mittelbar, beispielsweise ebenfalls über einen Federteller, an einem Speicherkolben 50 ab. Der Speicherkolben 50 ist in einer sich koaxial an den Federraum 46 anschließenden Bohrung 51 im Zwischenkörper 27 dicht geführt und begrenzt mit seiner der Schließfeder 44 abgewandten Stirnseite in der Bohrung 51 einen Speicherraum 52. Der Speicherraum 52 weist eine durch den Zwischenkörper 27, die Scheibe 15 und den Pumpenkörper 14 verlaufende Verbindung 54 mit dem Pumpenarbeitsraum 22 auf. Der Ventilkörper 26 und der Pumpenkörper 14 sind mittels einer Spannmutter 60 unter Zwischenlage des Federhaltekörpers 45, des Zwischenkörpers 27 sowie der Scheibe 15 miteinander verbunden und verspannt. Die Spannmutter 60 übergreift den Ventilkörper 26 und ist auf ein am Pumpenkörper 14 ausgebildetes Außengewinde aufgeschraubt. Zwischen der Spannmutter 60 und dem Ventilkörper 26 ist auf Höhe des Druckraums 40 und der Bohrung 30, in der das Einspritzventilglied 28 dicht geführt ist, ein Ringraum 62 gebildet. Die Spannmutter 60 weist im Bereich des Ringraums 62 in ihrem Umfang eine Vielzahl von Öffnungen 64 mit jeweils geringem Querschnitt auf, die Filteröffnungen bilden. Die Spannmutter 60 ist im Bereich des Ringraums 62 auf ihrer Aussenseite von einem weitere Ringraum 66 umgeben, der zwischen der Spannmutter 60 und einer Bohrung 68 in einem Zylinderkopf der Brennkraftmaschine gebildet ist, in die die Kraftstoffeinspritzeinrichtung eingesetzt ist. In den Ringraum 66 mündet ein Kraftstoffzulauf von der Förderpumpe 21 her. Der durch die Förderpumpe 21 zugeführte Kraftstoff gelangt durch die Filteröffnungen 64 in den Ringraum 62 und aus diesem über Kanäle 70 in den Scheiben 43, im Federhaltekörper 45, im Zwischenkörper 27, in der Scheibe 50 sowie im Pumpenkörper 14 in einen Ventilraum 72 des Steuerventils 23. Durch ein Steuerventilglied 74 ist der Ventilraum 72 wahlweise je nach Schaltstellung mit dem Pumpenarbeitsraum 22 verbindbar und vom Pumpenarbeitsraum 22 trennbar. Der Ventilraum 72 weist ausserdem eine Verbindung mit einem Rücklauf zum Kraftstoffvorratsbehälter 24 auf.The closing spring 44 is supported on the one hand at least indirectly, for example via a spring plate, on the injection valve member 28 and on the other hand at least indirectly, for example likewise via a spring plate, on a storage piston 50. The storage piston 50 is guided in a bore 51 in the intermediate body 27, which is coaxial with the spring space 46, and delimits a storage space 52 in the bore 51 with its end face remote from the closing spring 44. The storage space 52 has a disk 15 through the intermediate body 27 and connection 54 running the pump body 14 to the pump working space 22. The valve body 26 and the pump body 14 are connected and clamped to one another by means of a clamping nut 60 with the spring holding body 45, the intermediate body 27 and the disk 15 being interposed. The clamping nut 60 engages over the valve body 26 and is screwed onto an external thread formed on the pump body 14. An annular space 62 is formed between the clamping nut 60 and the valve body 26 at the level of the pressure chamber 40 and the bore 30 in which the injection valve member 28 is tightly guided. In the area of the annular space 62, the clamping nut 60 has a multiplicity of openings 64, each with a small cross section, which form filter openings. The clamping nut 60 is surrounded on the outside in the region of the annular space 62 by a further annular space 66 which is formed between the clamping nut 60 and a bore 68 in a cylinder head of the internal combustion engine, into which the fuel injection device is inserted. A fuel inlet from the feed pump 21 opens into the annular space 66. The fuel supplied by the feed pump 21 passes through the filter openings 64 into the annular space 62 and out of this via channels 70 in the disks 43, in the spring holding body 45, in the intermediate body 27, in the disk 50 and in the pump body 14 into a valve space 72 of the control valve 23 Depending on the switching position, the valve chamber 72 can be connected to the pump working chamber 22 and separated from the pump working chamber 22 by a control valve member 74. The valve chamber 72 also has a connection with a return to the fuel reservoir 24.
Der Ringraum 62 bildet einen Niederdruckbereich, mit dem der Federraum 46 verbunden ist. Im Federhaltekörper 45 ist wie in Figur 1 dargestellt ein Kanal 76, beispielsweise in Form einer Bohrung, ausgebildet, der sich entlang dem Federraum 46 erstreckt. Der Kanal 76 setzt sich durch die Scheiben 43 fort und mündet in den Ringraum 62. Der Kanal 76 endet andererseits am Zwischenkörper 27. Der Federraum 46 ist mit dem Kanal 76 über eine Drosselstelle 78 verbunden, die nahe dem dem Speicherkolben 50 zugewandten Ende des Federraums 46 angeordnet ist. Der Kanal 76 erstreckt sich somit vom dem Speicherkolben 50 zugewandten Endbereich des Federraums 46 bis zum Ringraum 62 und weist eine große Länge auf. Der Niederdruckbereich 62 ist in Richtung der Längsachse 13 des Kraftstoffeinspritzventils 12 mit Abstand vom Federraum 46 angeordnet. Der Federraum 46 ist somit über den langen Kanal 76 mit dem den Niederdruckbereich bildenden Ringraum 62 verbunden, wobei der Kanal 76 einen Dämpfungsraum bildet, in dem Druckschwankungen im Ringraum 62 abgeschwächt werden, so dass diese nur zu geringen Druckschwankungen im Federraum 46 führen.The annular space 62 forms a low-pressure area to which the spring space 46 is connected. As shown in FIG. 1, a channel 76, for example in the form of a bore, is formed in the spring holding body 45 and extends along the spring chamber 46. The channel 76 continues through the disks 43 and opens into the annular space 62. The channel 76 ends on the other hand on the intermediate body 27. The spring chamber 46 is connected to the channel 76 via a throttle point 78 which is arranged near the end of the spring chamber 46 facing the accumulator piston 50. The channel 76 thus extends from the end region of the spring chamber 46 facing the storage piston 50 to the annular chamber 62 and has a great length. The low-pressure region 62 is arranged at a distance from the spring chamber 46 in the direction of the longitudinal axis 13 of the fuel injection valve 12. The spring chamber 46 is thus connected via the long channel 76 to the annular space 62 forming the low-pressure region, the channel 76 forming a damping chamber in which pressure fluctuations in the annular chamber 62 are weakened, so that these lead to only slight pressure fluctuations in the spring chamber 46.
Nachfolgend wird die Funktion der Kraftstoffeinspritzeinrichtung erläutert. Der Pumpenarbeitsraum 22 wird während des Saughubs des Pumpenkolbens 18 bei geöffnetem Steuerventil 23 mit Kraftstoff gefüllt. Dabei gelangt der durch die Förderpumpe 21 geförderte Kraftstoff in den Ringraum 66, tritt durch die Filteröffnungen 64 hindurch in den Ringraum 62 und gelngt aus diesem über die Kanäle 70 in den Ventilraum 72 und aus diesem in den Pumpenarbeitsraum 22. Beim Förderhub des Pumpenkolbens 18 ist das Steuerventil 23 zunächst geöffnet, so dass sich im Pumpenarbeitsraum 22 kein Hochdruck aufbauen kann. Wenn die Kraftstoffeinspritzung beginnen soll, so wird das Steuerventil 23 durch die Steuereinrichtung 25 geschlossen, so dass der Pumpenarbeitsraum 22 vom Ventilraum 72 und damit vom Kraftstoffzulauf und vom Rücklauf zum Kraftstoffvorratsbehälter 24 getrennt ist und sich in diesem Hochdruck aufbaut. Wenn der Druck im Pumpenarbeitsraum 22 und im Druckraum 40 so hoch ist, dass die über die Druckschulter 42 auf das Einspritzventilglied 28 wirkende Kraft in Öffnungsrichtung 29 größer ist als die Kraft der Schließfeder 44, so bewegt sich das Einspritzventilglied 28 in Öffnungsrichtung 29 und gibt die wenigstens eine Einspritzöffnung 32 frei, durch die Kraftstoff in den Brennraum des Zylinders eingespritzt wird. Der Speicherkolben 50 befindet sich hierbei in einer Ausgangsstellung, in der dieser am nächsten zur Scheibe 15 angeordnet ist. Der Druck im Pumpenarbeitsraum 22 steigt nachfolgend entsprechend dem Profil des Nockens 20 weiter an.The function of the fuel injection device is explained below. The pump working chamber 22 is filled with fuel during the suction stroke of the pump piston 18 with the control valve 23 open. The fuel delivered by the feed pump 21 enters the annular space 66, passes through the filter openings 64 into the annular space 62 and flows out of this via the channels 70 into the valve space 72 and out of this into the pump work space 22. When the pump piston 18 is in the delivery stroke the control valve 23 is initially opened, so that no high pressure can build up in the pump work chamber 22. When the fuel injection is to begin, the control valve 23 is closed by the control device 25, so that the pump working chamber 22 is separated from the valve chamber 72 and thus from the fuel inlet and the return to the fuel reservoir 24 and builds up in this high pressure. If the pressure in the pump working chamber 22 and in the pressure chamber 40 is so high that the force acting on the injection valve member 28 via the pressure shoulder 42 in the opening direction 29 is greater than the force of the closing spring 44, the injection valve member 28 moves in the opening direction 29 and opens the at least one injection opening 32, through which fuel is injected into the combustion chamber of the cylinder. The storage piston 50 is in a starting position in which it is arranged closest to the disk 15. The pressure in the pump work chamber 22 subsequently increases further in accordance with the profile of the cam 20.
Wenn die durch den im Pumpenarbeitsraum 22 herrschenden Druck auf den Speicherkolben 50 ausgeübte Kraft größer wird als die durch die Schließfeder 44 auf den Speicherkolben 50 ausgeübte Kraft, so führt der Speicherkolben 50 eine Ausweichhubbewegung aus und bewegt sich von der Scheibe 15 weg in den Federraum 46 hinein, wobei der Speicherraum 52 vergrößert wird. Hierbei wird eine Druckerhöhung im Federraum 46 verursacht, da aus diesem wegen der Drosselstelle 78 nur verzögert Kraftstoff ausströmen kann, und ausserdem die Vorspannung der Schließfeder 44 erhöht, die sich am Speicherkolben 50 abstützt. Der im Federraum 46 herrschende Druck erzeugt über den Federteller, über den sich die Schließfeder 44 am Einspritzventilglied 28 abstützt, eine in Schließrichtung auf das Einspritzventilglied 28 wirkende Kraft. Durch den Druckanstieg im Federraum 46 und die Erhöhung der Vorspannung der Schließfeder 44 ergibt sich eine erhöhte Kraft in Schließrichtung auf das Einspritzventilglied 28, so dass dieses wieder in Schließrichtung bewegt wird, mit seiner Dichtfläche 34 am Ventilsitz 36 zur Anlage kommt und die Einspritzöffnungen 32 verschließt, so dass die Kraftstoffeinspritzung unterbrochen wird. Das Kraftstoffeinspritzventil 12 ist dabei nur für eine kurze Zeitdauer geöffnet und es wird nur eine geringe Menge Kraftstoff als Voreinspritzung in den Brennraum eingespritzt. Die eingespritzte Kraftstoffmenge ist unter anderem von dem im Federraum 46 herrschenden Druck abhängig, der wie vorstehend angegeben eine in Schließrichtung auf das Einspritzventilglied 28 wirkende Kraft erzeugt. Beim Schließen des Steuerventils 23 zu Beginn der Hochdruckförderung des Pumpenkolbens 18 kommt es im den Niederdruckbereich bildenden Ringraum 62 zu einem Druckanstieg, der jedoch infolge des langen Kanals 76 und der Drosselstelle 78 nicht oder nur in geringem Masse zu einem Druckanstieg im Federraum 46 führt und somit die bei der Voreinspritzung eingespritzte Kraftstoffmenge nur wenig beeinflusst. Bei einer direkten Verbindung des Federraums 46 mit dem Niederdruckbereich 62 wie beim Stand der Technik würde der Druckanstieg im Niederdruckbereich 62 zu einem starken Druckanstieg im Federraum 46 führen, was zu einer starken Verringerung der bei der Voreinspritzung eingespritzten Kraftstoffmenge führt, so dass nicht die im Kennfeld vorgegebene Kraftstoffmenge eingespritzt werden kann.If the force exerted on the accumulator piston 50 by the pressure prevailing in the pump work chamber 22 becomes greater than the force exerted on the accumulator piston 50 by the closing spring 44, the accumulator piston 50 executes an evasive stroke movement and moves away from the disk 15 into the spring chamber 46 into it, with the storage space 52 being enlarged. This causes an increase in pressure in the spring chamber 46, since fuel can flow out of it only with a delay because of the throttle point 78, and also increases the pretension of the closing spring 44, which is supported on the accumulator piston 50. The pressure prevailing in the spring chamber 46 generates, via the spring plate, by means of which the closing spring 44 is supported on the injection valve member 28, a force acting on the injection valve member 28 in the closing direction. The pressure increase in the spring chamber 46 and the increase in the pretension of the closing spring 44 result in an increased force in the closing direction on the injection valve member 28, so that it is moved again in the closing direction, comes into contact with its sealing surface 34 on the valve seat 36 and closes the injection openings 32 so that fuel injection is stopped. The fuel injection valve 12 is only open for a short period of time and only a small amount of fuel is injected into the combustion chamber as a pre-injection. The amount of fuel injected depends, among other things, on the pressure prevailing in the spring chamber 46, which, as stated above, generates a force acting in the closing direction on the injection valve member 28. When the control valve 23 closes at the start of the high-pressure delivery of the pump piston 18, an increase in pressure occurs in the annular space 62 forming the low-pressure region, which, however, does not or only to a small extent lead to an increase in pressure in the spring chamber 46 due to the long channel 76 and the throttle point 78, and thus affects the amount of fuel injected during the pre-injection only slightly. With a direct connection of the spring chamber 46 to the low pressure region 62 as in the prior art, the pressure increase in the low pressure region 62 would lead to a strong pressure increase in the spring chamber 46, which leads to a sharp reduction in the fuel quantity injected during the pre-injection, so that it does not result in the map predetermined amount of fuel can be injected.
Der Öffnungshub des Einspritzventilglieds 28 während der Voreinspritzung kann durch eine Dämpfungseinrichtung hydraulisch begrenzt sein. Das Einspritzventilglied 28 taucht dabei mit einem Druckzapfen 80 in einen kraftstoffgefüllten Dämpfungsraum 82, der von einem durch eine Stirnfläche der Scheibe 43 gebildeten ortsfesten Absatz 84 begrenzt ist, der dabei einen Hubanschlag für eine Ringschulter 86 am Einspritzventilglied 28 bildet. Dabei ist zwischen der Wand des Dämpfungsraums 82 und dem Druckzapfen 80 ein Drosselquerschnitt gebildet, der als Flächenanschliff 88 ausgebildet ist und über den der Dämpfungsraum 82 mit dem Federraum 46 verbunden ist. Der Flächenanschliff 88 am Druckzapfen 80 weist einen axialen Abstand zur Ringschulter 86 am Einspritzventilglied 28 auf, in dessen Bereich der Druckzapfen 80 dem Durchmesser der Bohrung in der Scheibe 43 entspricht, so dass eine Steuerkante 90 gebildet ist, deren Überfahren über den Absatz 84 das Zusteuern des hydraulischen Dämpfungsraums 82 steuert. Bei der Voreinspritzung durchläuft das Einspritzventilglied 28 nur einen Teilöffnungshub, der durch das Überfahren der Steuerkante 90 am Einspritzventilglied 28 über den Absatz 84 der Scheibe 43 begrenzt wird, in dessen Folge der Dämpfungsraum 82 zugesteuert wird, so dass sich die Schließkraft auf das Einspritzventilglied 28 erhöht.The opening stroke of the injection valve member 28 during the pre-injection can be hydraulically limited by a damping device. The injection valve member 28 dips with a pressure pin 80 into a fuel-filled damping space 82, which is delimited by a fixed shoulder 84 formed by an end face of the disk 43, which forms a stroke stop for an annular shoulder 86 on the injection valve member 28. In this case, a throttle cross section is formed between the wall of the damping chamber 82 and the pressure pin 80, which is designed as a ground section 88 and via which the damping chamber 82 is connected to the spring chamber 46. The surface grinding 88 on the pressure pin 80 is axially spaced from the annular shoulder 86 on the injection valve member 28, in the area of which the pressure pin 80 corresponds to the diameter of the bore in the disk 43, so that a control edge 90 is formed, the traversing of which via the shoulder 84 controls the control of the hydraulic damping chamber 82 controls. In the Pre-injection runs through the injection valve member 28 only a partial opening stroke, which is limited by driving over the control edge 90 on the injection valve member 28 via the shoulder 84 of the disk 43, as a result of which the damping chamber 82 is closed, so that the closing force on the injection valve member 28 increases.
Der Druck im Pumpenarbeitsraum 22 steigt nachfolgend weiter an entsprechend dem Profil des Nockens 20, so daß die auf das Einspritzventilglied 28 wirkende Druckkraft in Öffnungsrichtung 29 wieder zunimmt und die infolge der erhöhten Vorspannung der Schließfeder 44 und dem erhöhten Druck im Federraum 46 erhöhte Schließkraft übersteigt, so daß das Kraftstoffeinspritzventil 12 wieder öffnet. Dabei wird eine größere Kraftstoffmenge über eine längere Zeitdauer eingespritzt als während der Voreinspritzung. Die Zeitdauer und die während dieser Haupteinspritzung eingespritzte Kraftstoffmenge werden durch den Zeitpunkt bestimmt, zu dem das Steuerventil 23 durch die Steuereinrichtung 25 wieder geöffnet wird. Nach dem Öffnen des Steuerventils 23 ist der Pumpenarbeitsraum 22 wieder mit dem Rücklauf zum Kraftstoffvorratsbehälter 24 verbunden, so dass dieser entlastet ist und das Kraftstoffeinspritzventil 12 schließt. Der Speicherkolben 50 wird durch die Kraft der Schließfeder 44 wieder in seine Ausgangsstellung zurückbewegt. The pressure in the pump work chamber 22 subsequently increases further in accordance with the profile of the cam 20, so that the pressure force acting on the injection valve member 28 increases again in the opening direction 29 and exceeds the increased closing force as a result of the increased preload of the closing spring 44 and the increased pressure in the spring chamber 46, so that the fuel injection valve 12 opens again. A larger amount of fuel is injected over a longer period of time than during the pre-injection. The time period and the amount of fuel injected during this main injection are determined by the point in time at which the control valve 23 is opened again by the control device 25. After opening the control valve 23, the pump work chamber 22 is connected again to the return to the fuel reservoir 24, so that it is relieved and the fuel injection valve 12 closes. The storage piston 50 is moved back into its starting position by the force of the closing spring 44.

Claims

Ansprüche Expectations
1. Kraftstoffeinspritzeinrichtung für eine Brennkraftmaschine mit einer Kraftstoffhochdruckpumpe (10) und einem Kraftstoffeinspritzventil (12) für einen Zylinder der Brennkraftmaschine, wobei die Kraftstoffhochdruckpumpe1. Fuel injection device for an internal combustion engine with a high-pressure fuel pump (10) and a fuel injection valve (12) for a cylinder of the internal combustion engine, the high-pressure fuel pump
(10) einen durch die Brennkraftmaschine angetriebenen, einen Pumpenarbeitsraum (22) begrenzenden Pumpenkolben (18) aufweist, mit einem elektrisch betätigten Steuerventil (23) , durch das zumindest mittelbar eine Verbindung des Pumpenarbeitsraums (22) mit einem Entlastungsbereich (24) gesteuert wird, wobei das Kraftstoffeinspritzventil (12) wenigstens ein Einspritzventilglied (28) aufweist, durch das wenigstens eine Einspritzöffnung (32) gesteuert wird und das durch den in einem eine Verbindung (48) mit dem Pumpenarbeitsraum (22) aufweisenden Druckraum (40) herrschenden Druck gegen die Kraft einer in einem Federraum(10) has a pump piston (18) driven by the internal combustion engine and delimiting a pump work chamber (22), with an electrically operated control valve (23), by means of which a connection of the pump work chamber (22) to a relief region (24) is controlled at least indirectly, wherein the fuel injection valve (12) has at least one injection valve member (28) through which at least one injection opening (32) is controlled and which is opposed by the pressure prevailing in a pressure chamber (40) having a connection (48) to the pump working chamber (22) Force one in a spring chamber
(46) angeordneten Schließfeder (44) in einer Öffnungsrichtung (29) bewegbar ist, wobei sich die Schließfeder (44) einerseits zumindest mittelbar am Einspritzventilglied (28) und andererseits zumindest mittelbar an einem verschiebbaren Speicherkolben (50) abstützt, der auf seiner der Schließfeder (44) abgewandten Seite einen eine Verbindung (54) mit dem Pumpenarbeitsraum(46) arranged closing spring (44) is movable in an opening direction (29), the closing spring (44) on the one hand being supported at least indirectly on the injection valve member (28) and on the other hand at least indirectly on a displaceable storage piston (50) which rests on the closing spring (44) facing away from a connection (54) with the pump work space
(22) aufweisenden Speicherraum (52) begrenzt und der durch den im Speicherraum (52) herrschenden Druck beaufschlagt gegen die Kraft der Schließfeder (44) in den Federraum (46) bewegbar ist, wobei der Federraum (46) über eine Drosselstelle (78) eine Verbindung (76) mit einem Niederdruckbereich (62) aufweist, der mit einem KraftstoffZulauf und mit dem Entlastungsbereich (24) verbunden ist, dadurch gekennzeichnet, dass die Verbindung des Federraums (46) mit dem Niederdruckbereich (62) durch einen Kanal (76) gebildet ist, der sich entlang dem(22) having a storage space (52) and the pressure exerted by the pressure prevailing in the storage space (52) can be moved into the spring space (46) against the force of the closing spring (44), the spring space (46) via a throttle point (78) has a connection (76) with a low-pressure area (62) which is connected to a fuel inlet and to the relief area (24) is connected, characterized in that the connection of the spring chamber (46) to the low pressure region (62) is formed by a channel (76) which extends along the
Federraum (46) erstreckt, wobei der Federraum (46) übe ir dieSpring chamber (46) extends, the spring chamber (46) over the
Drosselstelle (78) mit einem Endbereich des Kanals (76) verbunden ist und der Kanal (76) an seinem entgegengesetzten Ende in den Niederdruckbereich (62) mündet.Throttle point (78) is connected to an end region of the channel (76) and the channel (76) opens into the low-pressure region (62) at its opposite end.
2. Kraftstoffeinspritzeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass sich der Kanal (76) von dem dem Speicherkolben (50) zugewandten Ende des Federraums (46) bis wenigstens zu dem dem Speicherkolben (50) abgewandten Ende des Federraums (46) erstreckt.2. Fuel injection device according to claim 1, characterized in that the channel (76) extends from the end of the spring chamber (46) facing the storage piston (50) to at least the end of the spring chamber (46) facing away from the storage piston (50).
3. Kraftstoffeinspritzeinrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass der Niederdruckbereich (62) als ein einen Ventilkörper (26) des Kraftstoffeinspritzventils (12) umgebender und in Richtung der Längsachse (13) des3. Fuel injection device according to claim 1 or 2, characterized in that the low pressure region (62) as a valve body (26) surrounding the fuel injection valve (12) and in the direction of the longitudinal axis (13) of the
Kraftstoffeinspritzventils (12) mit Abstand vom Federraum (46) angeordneter Ringraum ausgebildet ist.Fuel injection valve (12) is formed at a distance from the spring chamber (46) arranged annular space.
4. Kraftstoffeinspritzeinrichtung nach Anspruch 3, dadurch gekennzeichnet, dass der Niederdruckbereich (62) zumindest annähernd auf Höhe des Druckraums (40) des Kraftstoffeinspritzventils (12) angeordnet ist.4. Fuel injection device according to claim 3, characterized in that the low-pressure region (62) is arranged at least approximately at the level of the pressure chamber (40) of the fuel injection valve (12).
5. Kraftstoffeinspritzeinrichtung nach Anspruch 3 oder 4, dadurch gekennzeichnet, dass der Niederdruckbereich (62) als ein zwischen dem Ventilkörper (26) und einer diesen umgebenden Spannmutter (60) ausgebildet ist, wobei durch die Spannmutter (60) der Ventilkörper (26) mit einem Pumpenkörper (14) der Kraftstoffhochdruckpumpe (10) verbunden ist und die Spannmutter (60) in ihrem Umfang mehrere Öffnungen (74) aufweist, über die der Niederdruckbereich (62) mit dem KrafftstoffZulauf verbunden ist. 5. Fuel injection device according to claim 3 or 4, characterized in that the low-pressure region (62) is designed as a between the valve body (26) and a clamping nut (60) surrounding the latter, the valve body (26) with the clamping nut (60) a pump body (14) of the high-pressure fuel pump (10) is connected and the clamping nut (60) has a plurality of openings (74) in its periphery, via which the low-pressure region (62) is connected to the fuel supply.
6. Kraftstoffeinspritzeinrichtung nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass der Kanal (76) eine so große Länge aufweist, dass im Niederdruckbereich (62) auftretende Druckschwankungen so stark gedämpft werden, dass diese zu keinen oder nur geringen Druckschwankungen im Federraum (46) führen. 6. Fuel injection device according to one of the preceding claims, characterized in that the channel (76) has such a large length that pressure fluctuations occurring in the low-pressure region (62) are damped to such an extent that there are no or only slight pressure fluctuations in the spring chamber (46) to lead.
EP03815794A 2003-03-17 2003-10-18 Fuel injection device for a combustion engine Expired - Lifetime EP1606511B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE2003111522 DE10311522A1 (en) 2003-03-17 2003-03-17 Fuel injection device for an internal combustion engine
DE10311522 2003-03-17
PCT/DE2003/003495 WO2004083624A1 (en) 2003-03-17 2003-10-18 Fuel injection device for a combustion engine

Publications (2)

Publication Number Publication Date
EP1606511A1 true EP1606511A1 (en) 2005-12-21
EP1606511B1 EP1606511B1 (en) 2007-06-06

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EP03815794A Expired - Lifetime EP1606511B1 (en) 2003-03-17 2003-10-18 Fuel injection device for a combustion engine

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EP (1) EP1606511B1 (en)
DE (2) DE10311522A1 (en)
WO (1) WO2004083624A1 (en)

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Publication number Priority date Publication date Assignee Title
FR3017905B1 (en) * 2014-02-24 2018-12-07 Delphi International Operations Luxembourg S.A R.L. FUEL INJECTOR

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Publication number Priority date Publication date Assignee Title
GB9624513D0 (en) * 1996-11-26 1997-01-15 Lucas Ind Plc Injector
DE19844891A1 (en) * 1998-09-30 2000-04-06 Bosch Gmbh Robert Fuel injection valve for internal combustion engines
DE10124511A1 (en) * 2001-05-19 2002-11-21 Volkswagen Ag Fuel injection system control process involves afterflow parameter being controlled in dependence on main flow parameter
DE10141678A1 (en) * 2001-08-25 2003-05-08 Bosch Gmbh Robert Fuel injection device for an internal combustion engine

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2004083624A1 *

Also Published As

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EP1606511B1 (en) 2007-06-06
DE50307438D1 (en) 2007-07-19
DE10311522A1 (en) 2004-09-30
WO2004083624A1 (en) 2004-09-30

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