EP1651862A1 - Control valve for a fuel injector comprising a pressure exchanger - Google Patents

Control valve for a fuel injector comprising a pressure exchanger

Info

Publication number
EP1651862A1
EP1651862A1 EP04738706A EP04738706A EP1651862A1 EP 1651862 A1 EP1651862 A1 EP 1651862A1 EP 04738706 A EP04738706 A EP 04738706A EP 04738706 A EP04738706 A EP 04738706A EP 1651862 A1 EP1651862 A1 EP 1651862A1
Authority
EP
European Patent Office
Prior art keywords
servo valve
piston
pressure
sealing seat
seat
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
EP04738706A
Other languages
German (de)
French (fr)
Other versions
EP1651862B1 (en
Inventor
Hans-Christoph Magel
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 EP1651862A1 publication Critical patent/EP1651862A1/en
Application granted granted Critical
Publication of EP1651862B1 publication Critical patent/EP1651862B1/en
Anticipated expiration legal-status Critical
Expired - Fee Related 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
    • F02M47/00—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
    • F02M47/02—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure of accumulator-injector type, i.e. having fuel pressure of accumulator tending to open, and fuel pressure in other chamber tending to close, injection valves and having means for periodically releasing that closing pressure
    • F02M47/027—Electrically actuated valves draining the chamber to release the closing pressure
    • 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
    • F02M57/025—Injectors structurally combined with fuel-injection pumps characterised by the pump drive hydraulic, e.g. with pressure amplification
    • 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
    • F02M63/0014—Valves characterised by the valve actuating means
    • F02M63/0015—Valves characterised by the valve actuating means electrical, e.g. using solenoid
    • F02M63/0026—Valves characterised by the valve actuating means electrical, e.g. using solenoid using piezoelectric or magnetostrictive actuators
    • 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
    • F02M63/0028—Valves characterised by the valve actuating means hydraulic
    • F02M63/0029—Valves characterised by the valve actuating means hydraulic using a pilot valve controlling a hydraulic chamber
    • 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
    • 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
    • F02M63/0045—Three-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
    • 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
    • F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
    • F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails

Definitions

  • Stroke-controlled high-pressure accumulator injection systems can be used to inject fuel into direct-injection ner internal combustion engines. These fuel injection systems are characterized by the fact that the injection pressure can be adapted to the load and speed of the ner internal combustion engine. A high injection pressure is required to reduce emissions and achieve high specific outputs. Since the achievable pressure level in high-pressure fuel pumps is limited for reasons of strength, a further increase in pressure in high-pressure injection systems (common rail) can be achieved via pressure intensifiers on injectors.
  • DE 101 23 913 discloses a fuel injection device for internal combustion engines with a fuel injector that can be supplied by a high-pressure fuel source.
  • a pressure transmission device having a movable pressure booster piston is connected between the fuel injector and the high-pressure fuel source.
  • the pressure booster piston separates a space that can be connected to the high-pressure fuel source from a high-pressure space that is connected to the fuel injector.
  • the fuel pressure in the high-pressure chamber can be varied by infecting a rear space of the pressure booster device with fuel or by emptying the rear space of fuel.
  • the fuel injector has a movable closing piston for opening and closing injection openings, the closing piston protruding into a closing pressure chamber.
  • Fuel pressure can be applied to the closing piston to achieve a force acting on the closing piston in the closing direction.
  • the closing pressure chamber and the rear chamber are formed by a common closing pressure rear chamber, all partial areas of the closing pressure rear chamber being permanently connected to one another for the exchange of fuel.
  • a pressure chamber is provided for supplying fuel to the injection opening and for applying a force acting in the opening direction to the closing piston.
  • the high-pressure chamber is connected to the high-pressure fuel source in such a way that, apart from pressure vibrations, at least the fuel pressure of the high-pressure fuel source can be constantly present in the high-pressure chamber.
  • the pressure- The space and the high-pressure space are formed by a common injection space, the partial areas of which are permanently connected to one another for the exchange of fuel.
  • servo valves can be used as switching valves which have a one-piece servo valve piston in the seat-slide design of the control cross sections.
  • servo valves in the form of seat slide valve designs used as switching valves high wear on the slide edges can occur, since only small overlap lengths can be achieved.
  • servo valves designed in a seat-slide design place high demands on the manufacturing accuracy, particularly with regard to the position of the control edges of the servo valve piston relative to one another.
  • the embodiment proposed according to the invention of a switching valve designed as a servo valve in a 3/2-seat design for controlling a fuel injector comprises a valve needle on which a first needle piston is formed, which has a first sealing seat. On the first needle piston there is another, second needle piston, which has the function of a sealing sleeve. A second sealing seat is formed on the second needle piston, the second needle piston being designed against a valve housing by means of a spring supported on the first needle piston, and forming the second sealing seat with the latter. Due to this design of the valve needle of the 3/2-seat valve proposed according to the invention, the second sealing seat closes after a substantially smaller partial valve stroke.
  • the first sealing seat opens regardless of the closing of the second sealing seat up to a much larger stroke.
  • the solution proposed according to the invention of designing a switching valve controlling a fuel injector as a 3/2-seat seat valve enables an optimal injector coordination without large losses.
  • the proposed two-part servo valve according to the invention can advantageously be used in fuel injectors that include a pressure intensifier, be it integrated into or attached to the fuel injector, which are controlled by pressure relief or pressurization of the differential pressure chamber (rear space) of the pressure intensifier.
  • Figure 1 shows an embodiment of a valve designed as a 3/2-seat switch valve for a fuel injector with pressure booster in the deactivated state
  • FIG 2 shows the 3/2-seat switch valve shown in Figure 1 in the activated state.
  • FIG. 1 shows an exemplary embodiment of a 3/2-seat seat switching valve for a fuel injector, this fuel injector comprising a pressure booster.
  • a fuel injector 1 comprises a pressure intensifier 2 and a switching valve which is designed as a servo valve 3.
  • the servo valve 3 can be actuated via an actuator 4.
  • the actuator 4 can be designed on the one hand as a solenoid valve or as a piezo actuator, optionally with the interposition of a hydraulic coupling space.
  • the fuel injector 1 is supplied with fuel under high pressure via a pressure accumulator 5 (common rail).
  • the system pressure is present within the pressure accumulator 5 at the pressure intensifier 2 in its working space 7 via a high-pressure line 6.
  • the pressure booster 2 also includes a differential pressure space 8 (rear space), which is separated from the working space 7 via a booster piston 10, 11.
  • the two-part booster piston comprises a first booster piston part 10 and a second booster piston part 11.
  • the second booster piston part 11 is acted upon by a spring element 12 supported on the bottom of the differential pressure chamber 8, via which the booster piston 10, 11 returns to its rest position against one in the working chamber 7 arranged stop ring 13 are placed.
  • a compression space 9 of the pressure booster 2 is acted upon with increased pressure in accordance with the gear ratio of the pressure booster 2.
  • a nozzle chamber inlet 14 extends from the compression chamber 9 to a nozzle chamber 17 of the fuel injector 1.
  • the compression chamber 9 is refilled when the pressure intensifier 2 is deactivated via a filling valve 16, which in the illustration according to FIG. 1 is designed as a check valve.
  • the translation piston, 1, which is formed in two parts (see reference numerals 10, 11), can also be made in one part.
  • the nozzle chamber 17 encloses an injection valve member 18 designed as a nozzle needle, which has a pressure stage 19.
  • An annular gap 20 extends from the nozzle chamber 17 to a seat 21 of the injection valve member 8.
  • Below the seat 21 there are injection openings 22, via which fuel is injected into the combustion chamber of an internal combustion engine when the injection valve member 18 is lifted out of the seat 21.
  • the end face of the injection valve member 18 is acted upon by a closing piston 23, the spherical end face of which contacts the end face of the needle-shaped injection valve member 18.
  • An overflow throttle 24 is received in the closing piston 23, via which a through bore 27 of the closing piston 23 communicates with a space receiving a spring element 25.
  • the closing piston 23 is acted upon in the closing direction by the spring element 25.
  • a control chamber line 15, into which a first throttle point 26 is formed, extends from the hydraulic chamber receiving the spring element 25 to the differential pressure chamber 8 (rear chamber) of the pressurizer 2.
  • the pressure relief of the differential pressure chamber 8 of the pressure booster 2 takes place via a relief line 28. This ends in a valve housing 29 of the servo valve 3 at an orifice point 40.
  • a servo valve piston 30 is accommodated in the valve housing 29 of the servo valve 3.
  • the servo valve piston 30 comprises a through channel 31, which has a second throttle point 32.
  • the second throttle point 32 lies at the mouth of the through-channel 31 into a control chamber 33 of the servo valve 3.
  • From the control chamber 33 a line branches off into the first low-pressure side return 35, in which a discharge throttle 34 is received.
  • the control chamber 33 of the servo valve 3 can be depressurized by actuating the actuator 4, wherein the actuator 4 can be designed either as a solenoid valve or as a piezo actuator.
  • the servo valve piston 30 is surrounded by a servo valve chamber 36, from which branches off a second low-pressure-side return 37 for controlling control volumes.
  • the two returns 35, 37 can also be brought together within the injector and connected to a common return system.
  • a first sealing seat 38 is formed, which cooperates with an annular surface of a first shaft region 46 of the servo valve piston 30.
  • a second, reduced diameter second shaft area 47 follows, which is enclosed by an annular space 39 within the servo valve housing 29.
  • the second shaft area 47 of the servo valve piston has a stop surface 49 for one on the first servo valve piston 30 second servo valve piston 41 movably received.
  • the second servo valve piston 41 is movably mounted on the first servo valve piston 30 within a third sheep area 48 and is acted upon by a spring element 42, which is supported on a spring element support 43 at the lower end of the third shaft area 48.
  • the third shaft area 48 of the first servo valve piston 30 has an end face 45 on the working space side, which is acted upon by the pressure prevailing in the working space 7 of the pressure booster 2.
  • the second movably received servo valve piston 41 has a contoured piston surface 44, which forms a further, second sealing seat 50 with the valve housing 29.
  • the system pressure prevailing in the working space 7 of the pressure intensifier 2 is present via the opened second sealing seat 50 below the servo valve housing 29 via the outlet point 40, the relief line 28 in the differential pressure space 8 (rear space) of the pressure intensifier 2.
  • the pressure booster 2 is thus compensated for by the identical pressure prevailing in the working space 7 and in the differential pressure space 8 (rear space) and there is no pressure amplification.
  • the second return 37 on the low-pressure side is closed by the first stem region 46 of the first servo valve piston 30 placed in the first sealing seat 38;
  • the first return 35 on the low-pressure side is likewise closed via the actuator 4, which is also moved into its closed position.
  • the differential pressure chamber 8 of the pressure booster 2 is depressurized via the relief line 28.
  • the actuator 4 designed as a solenoid valve or a piezo actuator is activated in such a way that the first low-pressure return 35 is opened.
  • fuel flows out of the control chamber 33 of the servo valve 3 into the first return 35 on the low pressure side, so that the end face of the first servo valve piston 30 moves into the control chamber 33 of the servo valve 3.
  • the second sealing seat 50 is closed earlier than the first sealing seat 38 is fully opened.
  • the second sealing seat 50 can be closed completely after a small valve stroke, the first of which being independent of this Sealing seat 38 opens in accordance with a further stroke of the first servo valve piston 30.
  • This contributes significantly to an improvement in the injector dynamics of the fuel injector 1. Furthermore, the losses that occur when the pressure intensifier 2 is activated can be considerably reduced by the inventive design of the servo valve 3.
  • the actuator 4 is activated such that the first return 35 on the low-pressure side is closed again.
  • the pressure in the control chamber 33 of the servo valve 3 rises again owing to the fuel flowing in through the through channel 31 and flowing in from the working chamber 7.
  • the first servo valve piston 30 moves into the first sealing seat 38 and closes it.
  • the stop 49 on the piston side, formed on the second shaft area 47 of the first servo valve piston 30 strikes the second servo valve piston 41 and thus opens the second sealing seat 50 the relief line 28, fuel under system pressure, flows into the differential pressure chamber 8 of the pressure booster 2. Therefore, the two-part booster piston 10, 11 moves out of the compression space 9, in which fuel now flows in via the filling valve 16 from the cavity receiving the spring element 25 for refilling.
  • both the first sealing seat 38 and the second sealing seat 50 can be designed in a variety of ways.
  • the second servo valve piston 41 is designed, for example, with a contoured end face 44 which interacts with a flat seat on the servo valve housing 29.
  • the second sealing seat 50 can be closed after a small valve lift of the first servo valve piston 30, while the first sealing seat 38 opens independently of the closing of the second sealing seat 50.
  • the servo valve piston design proposed according to the invention means that the second sealing seat 50 is only opened by the piston-side stop 49 after the first sealing seat 38 to the second low-pressure side return 37 has already been partially closed is.
  • Pressure accumulator 30 first servo valve piston
  • Stop ring 38 first sealing seat
  • Locking piston 46 first piston shaft area

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

Abstract

The invention relates to a servo valve (3) for a fuel injector (1), comprising a pressure exchanger (2) having a working chamber (7) and a differential pressure chamber (8) which are separated by means of a pressure relay piston (10, 11). A control chamber (33) of the servo valve (3) can be connected to a first return pipe (35) on the low pressure side by means of an actuator (4), and the differential pressure chamber (8) of the pressure exchanger (2) can be connected to a second return pipe (37) on the low pressure side or a return pipe system consisting of the return pipes (35, 37). A first sealing seat (38) is formed on a first servo valve piston (30). A second servo valve piston (41) embodied as a sealing sleeve is received on the first servo valve piston (30), forming a second valve seat (50) with a valve housing (29). Said second valve seat closes earlier than the first sealing seat (38) when the pressure is relieved in the control chamber (33) during a small stroke of the piston. When the control chamber (33) is subjected to pressure, the second sealing seat (50) only opens once the first sealing seat (38) is closed.

Description

Schaltventil für einen Kraftstoffinjektor mit DruckübersetzerSwitch valve for a fuel injector with pressure intensifier
Technisches GebietTechnical field
Zum Einspritzen von Kraftstoff in direkt einspritzende Nerbrennungskraftmaschinen können hubgesteuerte Hochdruckspeichereinspritzsysteme (Common Rail) eingesetzt werden. Diese Kraftstoffeinspritzsysteme zeichnen sich dadurch aus, dass der Einspritzdruck an Last und Drehzahl der Nerbrennungskraftmaschine angepasst werden kann. Zur Reduzierung der Emissionen und zur Erzielung hoher spezifischer Leistungen ist ein hoher Einspritzdruck erforderlich. Da das erreichbare Druckniveau in Hochdruckfoaftstoffpumpen aus Festigkeitsgründen begrenzt ist, kann eine weitere Drucksteigerung bei Hochdruckein- Spritzsystemen (Common Rail) über Druckübersetzer an Injektoren erzielt werden.Stroke-controlled high-pressure accumulator injection systems (common rail) can be used to inject fuel into direct-injection ner internal combustion engines. These fuel injection systems are characterized by the fact that the injection pressure can be adapted to the load and speed of the ner internal combustion engine. A high injection pressure is required to reduce emissions and achieve high specific outputs. Since the achievable pressure level in high-pressure fuel pumps is limited for reasons of strength, a further increase in pressure in high-pressure injection systems (common rail) can be achieved via pressure intensifiers on injectors.
Stand der TechnikState of the art
DE 101 23 913 offenbart eine Kraftstoffeinspritzeinrichtung für Brennlcraftmaschinen mit einem von einer Kraftstoffhochdruckquelle versorgbaren Kraftstoffinjelctor. Zwischen dem Kraftstoffmjektor und der Kraftstoffhochdruckquelle ist eine einen beweglichen Druckübersetzerkolben aufweisende Druckübersetzungseinrichtung geschaltet. Deren Druckübersetzerkolben trennt einen an die Kraftstoffhochdruckquelle anschließbaren Raum von ei- nem mit dem Kraftstoffmjektor verbundenen Hochdruckraum. Durch Befallen eines Rückraumes der Druckübersetzungseinrichtung mit Kraftstoff bzw. durch Entleeren des Rückraumes von Kraftstoff kann der Kraftstoffdruck im Hochdruckraum variiert werden. Der Kraftstoffmjektor weist einen beweglichen Schließkolben zum Öffnen und Verschließen von Einspritzöffnungen auf, wobei der Schließkolben in einen Schließdruckraum hinein- ragt. Der Schließkolben ist mit Kraftstoffdruck zur Erzielung einer in Schließrichtung auf den Schließkolben wirkenden Kraft beaufschlagbar. Der Schließdruckraum und der Rückraum werden durch einen gemeinsamen Schließdruck-Rückraum gebildet, wobei sämtliche Teilbereiche des Schließdruck-Rückraumes permanent zum Austausch von Kraftstoff miteinander verbunden sind. Es ist ein Druckraum zum Versorgen der Einspritzöffnung mit Kraftstoff und zum Beaufschlagen des Schließkolbens mit einer in Öffnungsrichtung wirkenden Kraft vorgesehen. Der Hochdruckraum steht derart mit der Kraftstoffhockdruck- quelle in Verbindung, dass im Hochdruckraum abgesehen von Druckschwingungen ständig zumindest der Kraftstoffdrack der Kraftstoffhochdruckquelle anliegen kann. Der Druck- raum und der Hochdruckraum werden durch einen gemeinsamen Einspritzraum gebildet, dessen Teilbereiche permanent zum Austausch von Kraftstoff miteinander verbunden sind.DE 101 23 913 discloses a fuel injection device for internal combustion engines with a fuel injector that can be supplied by a high-pressure fuel source. A pressure transmission device having a movable pressure booster piston is connected between the fuel injector and the high-pressure fuel source. The pressure booster piston separates a space that can be connected to the high-pressure fuel source from a high-pressure space that is connected to the fuel injector. The fuel pressure in the high-pressure chamber can be varied by infecting a rear space of the pressure booster device with fuel or by emptying the rear space of fuel. The fuel injector has a movable closing piston for opening and closing injection openings, the closing piston protruding into a closing pressure chamber. Fuel pressure can be applied to the closing piston to achieve a force acting on the closing piston in the closing direction. The closing pressure chamber and the rear chamber are formed by a common closing pressure rear chamber, all partial areas of the closing pressure rear chamber being permanently connected to one another for the exchange of fuel. A pressure chamber is provided for supplying fuel to the injection opening and for applying a force acting in the opening direction to the closing piston. The high-pressure chamber is connected to the high-pressure fuel source in such a way that, apart from pressure vibrations, at least the fuel pressure of the high-pressure fuel source can be constantly present in the high-pressure chamber. The pressure- The space and the high-pressure space are formed by a common injection space, the partial areas of which are permanently connected to one another for the exchange of fuel.
Bei Kraftstoffinjektoren können Servoventile als Schaltventile eingesetzt werden, die einen einteiligen Servoventilkolben in Sitz-Schieber-Ausführung der Steuerquerschnitte aufweisen. Bei solchen in Sitz-Schieber-Bauweise ausgeführten als Schaltventile eingesetzten Servoventilen kann ein hoher Verschleiß der Schieberkanten auftreten, da nur geringe Überdeckungslängen realisiert werden können. Ferner stellen in Sitz-Schieber-Ausführung ausgebildete Servoventile hohe Anforderungen an die Fertigungsgenauigkeit besonders hinsichtlich der Lage der Steuerkanten des Servoventilkolbens zueinander.In fuel injectors, servo valves can be used as switching valves which have a one-piece servo valve piston in the seat-slide design of the control cross sections. With such servo valves in the form of seat slide valve designs used as switching valves, high wear on the slide edges can occur, since only small overlap lengths can be achieved. Furthermore, servo valves designed in a seat-slide design place high demands on the manufacturing accuracy, particularly with regard to the position of the control edges of the servo valve piston relative to one another.
Darstellung der ErfindungPresentation of the invention
Die erfmdungsgemäß vorgeschlagene Ausgestaltung eines als Servoventil ausgebildeten Schaltventils in 3/2-Sitz-Sitz-Bauweise zur Steuerung eines Kraftstoffinjektors umfasst eine Ventilnadel, an welcher ein erster Nadelkolben ausgebildet ist, der einen ersten Dichtsitz aufweist. Auf dem ersten Nadelkolben befindet sich ein weiterer, zweiter Nadelkolben, der die Funktion einer Dichthülse hat. Am zweiten Nadelkolben ist ein zweiter Dichtsitz ausgebildet, wobei der zweite Nadelkolben mittels einer sich am ersten Nadelkolben abstützenden Feder gegen ein Ventilgehäuse, und mit diesem den zweiten Dichtsitz bildend, ausgebildet ist. Der zweite Dichtsitz schließt aufgrund dieser Ausbildung der Ventilnadel des erfindungsgemäß vorgeschlagenen 3/2-Sitz-Sitz- Ventils bereits nach einem wesentlich kleineren Ventilteilhub. Der erste Dichtsitz öffnet hingegen unabhängig vom Schließen des zweiten Dichtsitzes weiter bis zu einem weit größeren Hub. Die erfmdungsgemäß vorgeschlagene Lösung, ein einen Kraftstoffinjektor ansteuerndes Schaltventil als 3/2-Sitz-Sitz- Ventil auszugestalten, ermöglicht eine optimale Injektorabstimmung ohne große Verlustmengen. Das erfindungsgemäß vorgeschlagene zweiteilig ausgebildete Servoventil kann vorteilhafterweise bei Kraftstoffinjektoren eingesetzt werden, die einen Druckübersetzer umfassen, sei dieser in den Kraftstoffinjektor integriert oder an diesen angebaut, welche über eine Druckentlastung bzw. eine Druckbeaufschlagung des Differenzdrackraum.es (Rückraum) des Druckübersetzers angesteuert werden.The embodiment proposed according to the invention of a switching valve designed as a servo valve in a 3/2-seat design for controlling a fuel injector comprises a valve needle on which a first needle piston is formed, which has a first sealing seat. On the first needle piston there is another, second needle piston, which has the function of a sealing sleeve. A second sealing seat is formed on the second needle piston, the second needle piston being designed against a valve housing by means of a spring supported on the first needle piston, and forming the second sealing seat with the latter. Due to this design of the valve needle of the 3/2-seat valve proposed according to the invention, the second sealing seat closes after a substantially smaller partial valve stroke. The first sealing seat, on the other hand, opens regardless of the closing of the second sealing seat up to a much larger stroke. The solution proposed according to the invention of designing a switching valve controlling a fuel injector as a 3/2-seat seat valve enables an optimal injector coordination without large losses. The proposed two-part servo valve according to the invention can advantageously be used in fuel injectors that include a pressure intensifier, be it integrated into or attached to the fuel injector, which are controlled by pressure relief or pressurization of the differential pressure chamber (rear space) of the pressure intensifier.
Mit der erfindungsgemäß vorgeschlagenen Lösung werden die sich bei zu kleinen Überde- ckungslängen von Schieberdichtsitzen auftretenden Nachteile umgangen, die häufig zu hohen Verlustmengen und zu einer schlechten Inje tordynamik führen. ZeichnungWith the solution proposed according to the invention, the disadvantages that occur when the overlap lengths of the slide sealing seats are too small, which often lead to high losses and to poor inertia dynamics. drawing
Anhand der Zeiclinung wird die Erfindung nachstehend eingehender beschrieben.The invention is described in more detail below with reference to the drawing.
Es zeigt:It shows:
Figur 1 ein Ausführungsbeispiel eines als 3/2-Sitz-Sitz-Schaltventil ausgebildeten Ventils für einen Kraftstoffinjektor mit Druckverstärker im deaktivierten Zustand undFigure 1 shows an embodiment of a valve designed as a 3/2-seat switch valve for a fuel injector with pressure booster in the deactivated state and
Figur 2 das in Figur 1 dargestellte 3/2-Sitz-Sitz-Schaltventil im aktivierten Zustand.Figure 2 shows the 3/2-seat switch valve shown in Figure 1 in the activated state.
Ausfuhrungsvariantendesign variants
Der Darstellung gemäß Fig. 1 ist ein Ausfuhrungsbeispiel für ein 3/2-Sitz-Sitz-Schaltventil für einen Kraftstoffinjektor zu entnehmen, wobei dieser Kraftstoffinjektor einen Druckübersetzer umfasst.1 shows an exemplary embodiment of a 3/2-seat seat switching valve for a fuel injector, this fuel injector comprising a pressure booster.
Ein B raftstoffinjektor 1 umfasst einen Druckübersetzer 2 sowie ein Schaltventil, welches als Servoventil 3 ausgebildet ist. Das Servoventil 3 ist über einen Aktor 4 betätigbar. Der Aktor 4 kann einerseits als Magnetventil oder als Piezosteller gegebenenfalls unter Zwischenschaltung eines hydraulischen Kopplungsraumes ausgebildet sein.A fuel injector 1 comprises a pressure intensifier 2 and a switching valve which is designed as a servo valve 3. The servo valve 3 can be actuated via an actuator 4. The actuator 4 can be designed on the one hand as a solenoid valve or as a piezo actuator, optionally with the interposition of a hydraulic coupling space.
Der Kraftstoffinjektor 1 wird über einen Druckspeicher 5 (Common Rail) mit unter hohem Druck stehendem Kraftstoff versorgt. Über eine Hochdruckleitung 6 steht der Systemdruck innerhalb des Druckspeichers 5 am Druckübersetzer 2 in dessen Arbeitsraum 7 an. Der Druckübersetzer 2 umfasst darüber hinaus einen Differenzdruckraum 8 (Rückraum), der vom Arbeitsraum 7 über einen Übersetzerkolben 10, 11 getrennt ist. Der zweiteilig ausgebildete Übersetzerkolben umfasst einen ersten Übersetzerkolbenteil 10 und einen zweiten Übersetzerkolbenteil 11. Der zweite Übersetzerkolbenteil 11 ist durch eine sich am Boden des Differenzdruckraumes 8 abstützendes Feder element 12 beaufschlagt, über welchem die Übersetzerkolben 10, 11 wieder in ihre Ruhestellung gegen einen im Arbeitsraum 7 angeordneten Anschlagring 13 gestellt werden.The fuel injector 1 is supplied with fuel under high pressure via a pressure accumulator 5 (common rail). The system pressure is present within the pressure accumulator 5 at the pressure intensifier 2 in its working space 7 via a high-pressure line 6. The pressure booster 2 also includes a differential pressure space 8 (rear space), which is separated from the working space 7 via a booster piston 10, 11. The two-part booster piston comprises a first booster piston part 10 and a second booster piston part 11. The second booster piston part 11 is acted upon by a spring element 12 supported on the bottom of the differential pressure chamber 8, via which the booster piston 10, 11 returns to its rest position against one in the working chamber 7 arranged stop ring 13 are placed.
Über den zweiten Übersetzerkolbenteil 11 wird ein Kompressionsraum 9 des Drucküber- setzers 2 mit entsprechend des Übersetzungsverhältnisses des Druckübersetzers 2 erhöhtem Druck beaufschlagt. Vom Kompressionsraum 9 erstreckt sich ein Düsenraumzulauf 14 zu einem Düsenraum 17 des Kraftstoffinjektors 1. Die Wiederbefüllung des Kompressionsraums 9 bei deaktiviertem Druckübersetzer 2 erfolgt über ein Befüllventil 16, welches in der Darstellung gemäß Fig. 1 als Rückschlagventil ausgestaltet ist. Der Übersetzerkolben, der in der Darstellung gemäß Fig. 1 zweiteilig ausgebildet ist (vgl. Bezugszeichen 10, 11), kann auch einteilig ausgeführt sein.Via the second booster piston part 11, a compression space 9 of the pressure booster 2 is acted upon with increased pressure in accordance with the gear ratio of the pressure booster 2. A nozzle chamber inlet 14 extends from the compression chamber 9 to a nozzle chamber 17 of the fuel injector 1. The compression chamber 9 is refilled when the pressure intensifier 2 is deactivated via a filling valve 16, which in the illustration according to FIG. 1 is designed as a check valve. The translation piston, 1, which is formed in two parts (see reference numerals 10, 11), can also be made in one part.
Der Düsenraum 17 umschließt ein als Düsennadel ausgebildetes Einspritzventilglied 18, welches eine Druckstufe 19 aufweist. Vom Düsenraum 17 aus erstreckt sich ein Ringspalt 20 zu einem Sitz 21 des Einspritzventilglieds 8. Unterhalb des Sitzes 21 befinden sich Einspritzöffnungen 22, über welche bei aus dem Sitz 21 abgehobenen Einspritzventilglied 18 Kraftstoff in den Brennraum einer Verbrennungskraftmaschine eingespritzt wird. Die Stirnseite des Einspritzventilglieds 18 ist durch einen Schließkolben 23 beaufschlagt, des- sen ballig ausgebildete Stirnfläche die Stirnfläche des nadeiförmigen Einspritzventilglieds 18 kontaktiert. Im Schließkolben 23 ist eine Überströmdrossel 24 aufgenommen, über welche eine Durchgangsbohrung 27 des Schließkolbens 23 mit einem ein Federelement 25 aufnehmenden Raum in Verbindung steht. Über das Federelement 25 ist der Schließkolben 23 in Schließrichtung beaufschlagt. Vom das Federelement 25 aufnehmenden hydrauli- sehen Raum erstreckt sich eine Steuerraumleitung 15, in welche eine erste Drosselstelle 26 ausgebildet ist, zum Differenzdruckraum 8 (Rückraum) des Druckbesetzers 2.The nozzle chamber 17 encloses an injection valve member 18 designed as a nozzle needle, which has a pressure stage 19. An annular gap 20 extends from the nozzle chamber 17 to a seat 21 of the injection valve member 8. Below the seat 21 there are injection openings 22, via which fuel is injected into the combustion chamber of an internal combustion engine when the injection valve member 18 is lifted out of the seat 21. The end face of the injection valve member 18 is acted upon by a closing piston 23, the spherical end face of which contacts the end face of the needle-shaped injection valve member 18. An overflow throttle 24 is received in the closing piston 23, via which a through bore 27 of the closing piston 23 communicates with a space receiving a spring element 25. The closing piston 23 is acted upon in the closing direction by the spring element 25. A control chamber line 15, into which a first throttle point 26 is formed, extends from the hydraulic chamber receiving the spring element 25 to the differential pressure chamber 8 (rear chamber) of the pressurizer 2.
Die Druckentlastung des Differenzdruckraums 8 des Druckübersetzers 2 erfolgt über eine Entlastungsleitung 28. Diese mündet in einem Ventilgehäuse 29 des Servoventils 3 an ei- ner Mündungsstelle 40. Im Ventilgehäuse 29 des Servoventils 3 ist ein Servoventilkolben 30 aufgenommen. Der Servoventilkolben 30 umfasst einen Durchgangskanal 31, der eine zweite Drosselstelle 32 aufweist. Die zweite Drosselstelle 32 liegt an der Mündungsstelle des Durchgangskanals 31 in einen Steuerraum 33 des Servoventils 3. Vom Steuerraum 33 zweigt eine in den ersten niederdruckseitigen Rücklauf 35 verlaufende Leitung ab, in der eine Ablaufdrossel 34 aufgenommen ist. Der Steuerraum 33 des Servoventils 3 ist durch Betätigung des Aktors 4 druckentlastbar, wobei der Aktor 4 entweder als Magnetventil oder auch als Piezosteller ausgeführt werden kann.The pressure relief of the differential pressure chamber 8 of the pressure booster 2 takes place via a relief line 28. This ends in a valve housing 29 of the servo valve 3 at an orifice point 40. A servo valve piston 30 is accommodated in the valve housing 29 of the servo valve 3. The servo valve piston 30 comprises a through channel 31, which has a second throttle point 32. The second throttle point 32 lies at the mouth of the through-channel 31 into a control chamber 33 of the servo valve 3. From the control chamber 33, a line branches off into the first low-pressure side return 35, in which a discharge throttle 34 is received. The control chamber 33 of the servo valve 3 can be depressurized by actuating the actuator 4, wherein the actuator 4 can be designed either as a solenoid valve or as a piezo actuator.
Der Servoventilkolben 30 ist von einer Servo ventilkammer 36 umgeben, von der aus ein zweiter niederdruckseitiger Rücklauf 37 zur Absteuerung von Steuervolumen abzweigt. Die beiden Rückläufe 35, 37 können auch innerhalb des Injektors zusammengeführt sein und an ein gemeinsames Rücklaufsystem angeschlossen sein.The servo valve piston 30 is surrounded by a servo valve chamber 36, from which branches off a second low-pressure-side return 37 for controlling control volumes. The two returns 35, 37 can also be brought together within the injector and connected to a common return system.
Am Servo ventilgehäuse 29 ist ein erster Dichtsitz 38 ausgebildet, der mit einer Ringfläche eines ersten Schaftbereiches 46 des Servoventilkolbens 30 zusammenwirkt. An den ersten Schaftbereich 46 des Servoventilkolbens 30 schließt sich ein zweiter, in verringertem Durchmesser ausgebildeter zweiter Schaftbereich 47 an, der von einem Ringraum 39 innerhalb des Servo ventilgehäuses 29 umschlossen ist. Der zweite Schaftbereich 47 des Servoventilkolbens weist eine Anschlagfläche 49 für einen am ersten Servoventilkolben 30 beweglich aufgenommenen zweiten Servoventilkolben 41 auf. Der zweite Servoventilkolben 41 ist innerhalb eines dritten Schafbereichs 48 bewegbar am ersten Servoventilkolben 30 gelagert und über ein Federelement 42 beaufschlagt, welches sich an einer Federele- mentabstützung 43 am unteren Ende des dritten Schaftbereichs 48 abstützt. Der dritte Schaftbereich 48 des ersten Servoventilkolbens 30 weist eine arbeitsraumseitige Stirnfläche 45 auf, welche von dem im Arbeitsraum 7 des Druckübersetzers 2 herrschenden Druck beaufschlagt ist. Der zweite bewegbar aufgenommene Servoventilkolben 41 weist eine konturierte Kolbenfläche 44 auf, welche mit dem Ventilgehäuse 29 einen weiteren, zweiten Dichtsitz 50 bildet.On the servo valve housing 29, a first sealing seat 38 is formed, which cooperates with an annular surface of a first shaft region 46 of the servo valve piston 30. At the first shaft area 46 of the servo valve piston 30, a second, reduced diameter second shaft area 47 follows, which is enclosed by an annular space 39 within the servo valve housing 29. The second shaft area 47 of the servo valve piston has a stop surface 49 for one on the first servo valve piston 30 second servo valve piston 41 movably received. The second servo valve piston 41 is movably mounted on the first servo valve piston 30 within a third sheep area 48 and is acted upon by a spring element 42, which is supported on a spring element support 43 at the lower end of the third shaft area 48. The third shaft area 48 of the first servo valve piston 30 has an end face 45 on the working space side, which is acted upon by the pressure prevailing in the working space 7 of the pressure booster 2. The second movably received servo valve piston 41 has a contoured piston surface 44, which forms a further, second sealing seat 50 with the valve housing 29.
Im in Fig. 1 dargestellten deaktivierten Ruhezustand des Druckübersetzers 2 steht über den geöffneten zweiten Dichtsitz 50 unterhalb des Servoventilgehäuses 29 der im Arbeitsraum 7 des Druckübersetzers 2 herrschende Systemdruck über die Mündungsstelle 40, die Entlastungsleitung 28 im Differenzdruckraum 8 (Rückraum) des Druckübersetzers 2 an. Damit ist der Druckübersetzer 2 durch den im Arbeitsraum 7 und in den im Differenzdruckraum 8 (Rückraum) herrschenden identischen Druck ausgeglichen und es findet keine Druckverstärkung statt. Durch den in den ersten Dichtsitz 38 gestellten ersten Schaftbereich 46 des ersten Servoventilkolbens 30 ist der zweite niederdruckseitige Rücklauf 37 verschlossen; über den ebenfalls in seine Schließstellung gefahrenen Aktor 4 wird der erste niederdruckseitige Rücklauf 35 ebenfalls verschlossen.In the deactivated idle state of the pressure intensifier 2 shown in FIG. 1, the system pressure prevailing in the working space 7 of the pressure intensifier 2 is present via the opened second sealing seat 50 below the servo valve housing 29 via the outlet point 40, the relief line 28 in the differential pressure space 8 (rear space) of the pressure intensifier 2. The pressure booster 2 is thus compensated for by the identical pressure prevailing in the working space 7 and in the differential pressure space 8 (rear space) and there is no pressure amplification. The second return 37 on the low-pressure side is closed by the first stem region 46 of the first servo valve piston 30 placed in the first sealing seat 38; The first return 35 on the low-pressure side is likewise closed via the actuator 4, which is also moved into its closed position.
In dem in Fig. 1 dargestellten Ruhezustand des Druckübersetzers 2 findet keine Einspritzung statt, da über den im Differenzdruckraum 8 herrschenden Druck der Schließkolben 23 und das Einspritzventilglied 28 - unterstützt durch das Federelement 25 - in die Schließ- Stellung gefahren sind und im Düsenraum 17 keine an der Druckstufe 19 des Einspritzventilgliedes 18 in Öffnungsrichtung wirkende, erhöhte Druckkraft ansteht.In the idle state of the pressure booster 2 shown in FIG. 1, no injection takes place, since the closing piston 23 and the injection valve member 28 - supported by the spring element 25 - have moved into the closed position and none in the nozzle chamber 17 via the pressure prevailing in the differential pressure chamber 8 at the pressure stage 19 of the injection valve member 18, there is an increased pressure force acting in the opening direction.
Fig. 2 zeigt die Aktivierung des Druckübersetzers des Kraftstoffiηjektors bei Ansteuerung des Aktors.2 shows the activation of the pressure intensifier of the fuel injector when the actuator is activated.
Zur Ansteuerung des Druckübersetzers 2 wird der Differenzdruckraum 8 des Druckübersetzers 2 über die Entlastungsleitung 28 druckentlastet. Dazu erfolgt eine Ansteuerung des als Magnetventil oder Piezosteller ausgebildeten Aktors 4, derart, dass der erste niederdruckseitige Rücklauf 35 geöffnet wird. Nunmehr strömt aus dem Steuerraum 33 des Ser- voventils 3 Kraftstoff in den ersten niederdruckseitigen Rücklauf 35 ab, so dass sich der erste Servoventilkolben 30 mit seiner Stirnfläche in den Steuerraum 33 des Servoventils 3 bewegt. Bei der Aufwärtsbewegung des ersten Servoventilkolbens 30 wird der zweite Dichtsitz 50 früher geschlossen als der erste Dichtsitz 38 vollständig geöffnet wird. Daher strömt aus dem Differenzdruckraum 8 Kraftstoffvolumen über die Entlastungsleitung 28, die Mündungsstelle 40 über den Ringraum 39 in den zweiten niederdruckseitigen Rücklauf 37 ab, so dass der Übersetzerkolben 10, 11 nunmehr in den Kompressionsraum 9 einfährt. Aufgrund dessen gelangt entsprechend des Übersetzungsverhältnisses des Druckübersetzers 2 Kraftstoff unter erhöhtem Druck in den Düsenraum 17. Dadurch wird das Einspritz- ventilglied 18 durch eine an der Druckstufe 19 in Öffnungsrichtung wirkende erhöhte hydraulische Kraft beaufschlagt und öffnet, so dass die unterhalb des Sitzes 21 des Einspritzventilglieds 18 in den Brennraum mündenden Einspritzöffnungen 22 freigegeben werden. Nunmehr wird Kraftstoff in den Brennraum der Verbrennungskraftmaschine eingespritzt.To control the pressure booster 2, the differential pressure chamber 8 of the pressure booster 2 is depressurized via the relief line 28. For this purpose, the actuator 4 designed as a solenoid valve or a piezo actuator is activated in such a way that the first low-pressure return 35 is opened. Now fuel flows out of the control chamber 33 of the servo valve 3 into the first return 35 on the low pressure side, so that the end face of the first servo valve piston 30 moves into the control chamber 33 of the servo valve 3. When the first servo valve piston 30 moves upward, the second sealing seat 50 is closed earlier than the first sealing seat 38 is fully opened. Therefore, fuel volume flows out of the differential pressure chamber 8 via the relief line 28, the outlet point 40 via the annular space 39 into the second low-pressure side return 37, so that the booster piston 10, 11 now moves into the compression space 9. Because of this, fuel reaches the nozzle chamber 17 under increased pressure in accordance with the transmission ratio of the pressure intensifier 2. As a result, the injection valve member 18 is acted upon and opened by an increased hydraulic force acting on the pressure stage 19 in the opening direction, so that it is below the seat 21 of the injection valve member 18 injection openings 22 opening into the combustion chamber are released. Now fuel is injected into the combustion chamber of the internal combustion engine.
Bei der Druckentlastung des Steuerraumes 33 des Servoventils 3 wird bereits bei einem kleinen aufwärts gerichteten Hub der zweite Dichtsitz 50 zwischen dem Servoventilgehäu- se 29 und der konturierten Oberfläche 44 des zweiten Servoventilkolbens 41 geschlossen. Aufgrund der an der arbeitsraumseitigen Stirnfläche 45 des Servoventilkolbens 30 im Arbeitsraum 7 des Druckübersetzers 2 angreifenden Druckkraft wird der erste Servoventil- kolben 30 nach dem Schließen des zweiten Dichtsitzes 50 weiterbewegt, so dass der erste Dichtsitz 38 weiter öffnet.When the pressure in the control chamber 33 of the servo valve 3 is relieved, the second sealing seat 50 between the servo valve housing 29 and the contoured surface 44 of the second servo valve piston 41 is closed even with a small upward stroke. Due to the pressure force acting on the end face 45 of the servo valve piston 30 in the work area 7 of the pressure booster 2, the first servo valve piston 30 is moved further after the second sealing seat 50 has been closed, so that the first sealing seat 38 opens further.
Durch die erfindungsgemäße Ausgestaltung des ersten Servoventilkolbens 30, an welchem ein erster Dichtsitz 38 ausgebildet ist, sowie ein bewegbar, als Dichthülse fungierender zweiter Servoventilkolben 41 aufgenommen ist, kann der zweite Dichtsitz 50 bereits nach einem kleinen Ventilhub vollständig geschlossen werden, wobei davon unabhängig der erste Dichtsitz 38 entsprechend eines weitergehenden Hubweges des ersten Servoventilkolbens 30 öffnet. Dies trägt erheblich zu einer Verbesserung der Injektordynamik des Kraftstoffinjektors 1 bei. Ferner lassen sich die Verlustmengen, die bei der Ansteuerung des Druckübersetzers 2 auftreten, durch die erfindungsgemäße Ausgestaltung des Servoventils 3 erheblich reduzieren.Due to the design of the first servo valve piston 30 according to the invention, on which a first sealing seat 38 is formed and a moveable second servo valve piston 41, which acts as a sealing sleeve, the second sealing seat 50 can be closed completely after a small valve stroke, the first of which being independent of this Sealing seat 38 opens in accordance with a further stroke of the first servo valve piston 30. This contributes significantly to an improvement in the injector dynamics of the fuel injector 1. Furthermore, the losses that occur when the pressure intensifier 2 is activated can be considerably reduced by the inventive design of the servo valve 3.
Zum Beenden der Einspritzung wird der Aktor 4 derart angesteuert, dass der erste niederdruckseitige Rücklauf 35 wieder verschlossen wird. Dadurch steigt im Steuerraum 33 des Servoventils 3 der Druck aufgrund des über den Durchgangskanal 31 in diesen einströmenden, vom Arbeitsraum 7 aus zuströmenden Kraftstoff wieder an. Der erste Servoventilkolben 30 fahrt in den ersten Dichtsitz 38 und verschließt diesen. Bei der Einfahrbewegung des ersten Servoventilkolbens 30 in den ersten Dichtsitz 38 schlägt der kolbenseitig, am zweiten Schaftbereich 47 des ersten Servoventilkolbens 30 ausgebildete Anschlag 49 am zweiten Servoventilkolben 41 an und öffnet somit den zweiten Dichtsitz 50. Dadurch kann vom Arbeitsraum 7 über die Mündungsstelle 40 und die Entlastungsleitung 28 unter Systemdruck stehender Kraftstoff in den Differenzdruckraum 8 des Druckübersetzers 2 einströmen. Daher fährt der zweiteilige Übersetzerkolben 10, 11 aus dem Kompressionsraum 9 aus, in welchen nunmehr über das Befüllventil 16 vom das Federelement 25 aufnehmenden Hohlraum Kraftstoff zur Wiederbefüllung nachströmt.To end the injection, the actuator 4 is activated such that the first return 35 on the low-pressure side is closed again. As a result, the pressure in the control chamber 33 of the servo valve 3 rises again owing to the fuel flowing in through the through channel 31 and flowing in from the working chamber 7. The first servo valve piston 30 moves into the first sealing seat 38 and closes it. When the first servo valve piston 30 moves into the first sealing seat 38, the stop 49 on the piston side, formed on the second shaft area 47 of the first servo valve piston 30, strikes the second servo valve piston 41 and thus opens the second sealing seat 50 the relief line 28, fuel under system pressure, flows into the differential pressure chamber 8 of the pressure booster 2. Therefore, the two-part booster piston 10, 11 moves out of the compression space 9, in which fuel now flows in via the filling valve 16 from the cavity receiving the spring element 25 for refilling.
Zur Gewährleistung einer definierten Ausgangsstellung des am ersten Servoventilkol- ben 30 beweglich aufgenommenen zweiten Servoventilkolben 41 kann entweder ein Anschlag 49 oder ein Federelement 42 vorgesehen werden. Zur Unterstützung der Hubbewegung des ersten Servoventilkolbens 30 können Federelemente vorgesehen werden, die jedoch in der Ausführungsvariante gemäß der Figuren 1 und 2 nicht dargestellt sind. Sowohl der erste Dichtsitz 38 als auch der zweite Dichtsitz 50 können in vielfältiger Weise ausge- führt sein. Im in Fig. 1 und 2 dargestellten Ausführungsbeispiel ist der zweite Servoventilkolben 41 beispielsweise mit einer mit einem Flachsitz am Servoventilgehäuse 29 zusammenwirkenden konturierten Stirnfläche 44 ausgebildet. Neben einer Ausbildung als Flachsitz am Servoventilgehäuse 29 in Bezug auf den zweiten Dichtsitz 50 oder eine Ausgestaltung des ersten Dichtsitzes 38 als Kegelsitz, wie in Fig. 1 und 2 dargestellt, können auch andere Sitzgeometrien am ersten Dichtsitz 38 sowie am zweiten Dichtsitz 50 am Servoventil 3 eingesetzt werden.To ensure a defined starting position of the second servo valve piston 41, which is movably received on the first servo valve piston 30, either a stop 49 or a spring element 42 can be provided. To support the lifting movement of the first servo valve piston 30, spring elements can be provided, but these are not shown in the embodiment variant according to FIGS. 1 and 2. Both the first sealing seat 38 and the second sealing seat 50 can be designed in a variety of ways. In the exemplary embodiment shown in FIGS. 1 and 2, the second servo valve piston 41 is designed, for example, with a contoured end face 44 which interacts with a flat seat on the servo valve housing 29. In addition to being designed as a flat seat on the servo valve housing 29 in relation to the second sealing seat 50 or an embodiment of the first sealing seat 38 as a conical seat, as shown in FIGS. 1 and 2, other seat geometries on the first sealing seat 38 and on the second sealing seat 50 on the servo valve 3 can also be used be used.
Durch die erfindungsgemäß vorgeschlagene Ausgestaltung eines Servoventilkolbens als zweiteiliger Kolben 30, 41 kann einerseits der zweite Dichtsitz 50 nach einem kleinen Ven- tilhub des ersten Servoventilkolbens 30 geschlossen werden, während der erste Dichtsitz 38 unabhängig vom Schließen des zweiten Dichtsitzes 50 weiter öffnet. Zur Verringerung der Verlustmengen bei der Ansteuerung des Druckübersetzers 2 kann durch die erfϊn- dungsgemäß vorgeschlagene Servo ventilkolbenbauform erreicht werden, dass der zweite Dichtsitz 50 erst dann durch den kolbenseitigen Anschlag 49 geöffnet wird, nachdem der erste Dichtsitz 38 zum zweiten niederdruckseitigen Rücklauf 37 bereits teilweise geschlossen ist. Erst dann wird der zweite Dichtsitz 50 freigegeben, so dass der im Arbeitsraum 7 anstehende Systemdruck über die Entlastungsleitung 28 auch im Differenzdruckraum 8 des Druckübersetzers 2 anliegt und nur geringfügig in den zweiten niederdruckseitigen Rücklauf 37 abströmt, der bereits durch den ersten Schaftbereich 46 des ersten Servoventilkol- bens 30 am ersten Dichtsitz 38 nahezu vollständig geschlossen ist. Due to the inventive design of a servo valve piston as a two-part piston 30, 41, on the one hand, the second sealing seat 50 can be closed after a small valve lift of the first servo valve piston 30, while the first sealing seat 38 opens independently of the closing of the second sealing seat 50. In order to reduce the loss quantities when controlling the pressure booster 2, the servo valve piston design proposed according to the invention means that the second sealing seat 50 is only opened by the piston-side stop 49 after the first sealing seat 38 to the second low-pressure side return 37 has already been partially closed is. Only then is the second sealing seat 50 released, so that the system pressure present in the working space 7 is also present in the differential pressure space 8 of the pressure booster 2 via the relief line 28 and only flows slightly into the second low-pressure side return 37, which is already flowing through the first shaft area 46 of the first servo valve column - bens 30 is almost completely closed at the first sealing seat 38.
BezugszeichenlisteLIST OF REFERENCE NUMBERS
K-raftstoffinj ektor 26 erste DrosselstelleK-raftstoffinj ektor 26 first throttle
Druckübersetzer 27 Durchgangsbohrung SchließkolbenPressure intensifier 27 through bore of the closing piston
Servoventil 28 EntlastungsleitungServo valve 28 relief line
Aktor 29 Ventilgehäuse ServoventilActuator 29 valve housing servo valve
Druckspeicher 30 erster ServoventilkolbenPressure accumulator 30 first servo valve piston
Hochdruckleitung 31 DurchgangskanalHigh pressure line 31 through channel
Arbeitsraum (Drucküberset: zer) 32 zweite DrosselstelleWorking area (pressure ratio: zer) 32 second throttling point
Differenzdruckraum (Rückraum) 33 Steuerraum ServoventilDifferential pressure space (rear space) 33 Control valve servo valve
(Druckübersetzer) 34 Ablaufdrossel(Pressure intensifier) 34 Flow restrictor
Kompressionsraum (Druckübersetzer) 35 erster niederdruckseitiger Rücklauf erster Übersetzerkolben 36 Servoventilkammer zweiter Übersetzerkolben 37 zweiter niederdruckseitiger Rück¬Compression chamber (pressure booster) 35 first low-pressure side return first booster piston 36 servo valve chamber second booster piston 37 second low-pressure side Rück¬
Rückstellfeder laufReturn spring running
Anschlagring 38 erster DichtsitzStop ring 38 first sealing seat
Düsenraumzulauf 39 RingraumNozzle space inlet 39 annular space
Steuerraumleitung 40 Mündungsstelle EntlastungsleitungControl room line 40 discharge point discharge line
Befüllventil Kompressionsraum 41 zweiter ServoventilkolbenFilling valve compression chamber 41 second servo valve piston
Düsenraum 42 FederelementNozzle space 42 spring element
Einspritzventilglied 43 FederelementabstützungInjector valve member 43 spring element support
Druckstufe 44 konturierte Kolbenfläche zweiterPressure stage 44 contoured piston surface second
Ringspalt Servoventilkolben 41Annular gap servo valve piston 41
Sitz Einspritzventilglied 45 arbeitsraumseitige StirnflächeSeat injection valve member 45 end face on the work area
Einspritzöffnung zweiter Servoventilkolben 41Injection opening of second servo valve piston 41
Schließkolben 46 erster KolbenschaftbereichLocking piston 46 first piston shaft area
Überströmdrossel 47 zweiter KolbenschaftbereichOverflow throttle 47 second piston skirt area
Federelement 48 dritter Kolbenschaftbereich 49 kolbenseitiger Anschlag für zweiten Servoventilkolben 41 50 zweiter Dichtsitz Spring element 48 third piston shaft area 49 piston-side stop for second servo valve piston 41 50 second sealing seat

Claims

Patentansprüche claims
1. Servoventil (3) für einen Kraftstoffinjektor (1), der einen Druckübersetzer (2) aufweist, dessen Arbeitsraum (7) von einem Differenzdruckraum (8) über einen Überset- zerkolben (10, 11) getrennt ist, wobei ein Steuerraum (33) des Servoventils (3) über einen Aktor (4) mit einem niederdruckseitigen Rücklauf (35), und der Differenzdruckraum (8) des Druckübersetzers (2) mit einem niederdruckseitigen Rücklauf (37) oder einem die Rückläufe (35, 37) zusammenführenden Rücklaufsystem verbindbar sind, dadurch gekennzeichnet, dass an einem ersten Servoventilkolben (30) mit einer per- manent mit Systemdruck beaufschlagten Fläche (45) ein erster Dichtsitz (38) ausgebildet ist, und am ersten Servoventilkolben (30) ein als Dichthülse ausgebildeter zweiter Servoventilkolben (41) axial verschiebbar aufgenommen ist, der mit einem Ventilgehäuse (29) einen zweiten Dichtsitz (50) bildet, so dass der erste Servoventilkolben (30) nach dem Schließen des zweiten Dichtsitzes (50) durch den zweiten Servoventilkolben (41) ein weiteres Öffnen des ersten Dichtsitzes (38) bewirkt.1. Servo valve (3) for a fuel injector (1), which has a pressure booster (2), the working chamber (7) of which is separated from a differential pressure chamber (8) via a booster piston (10, 11), a control chamber (33 ) of the servo valve (3) via an actuator (4) with a low-pressure side return (35), and the differential pressure chamber (8) of the pressure booster (2) with a low-pressure side return (37) or a return system (36, 37) bringing together the return system characterized in that a first sealing seat (38) is formed on a first servo valve piston (30) with a surface (45) permanently subjected to system pressure, and on the first servo valve piston (30) a second servo valve piston (41) designed as a sealing sleeve. axially displaceable, which forms a second sealing seat (50) with a valve housing (29), so that the first servo valve piston (30) after the second sealing seat (50) has been closed by the second The servo valve piston (41) causes the first sealing seat (38) to open further.
2. Servoventil gemäß Anspruch 1, dadurch gekennzeichnet, dass der erste Dichtsitz (38) an einem ersten Schaftbereich (46) des ersten Servoventilkolbens (30) ausgebildet ist.2. Servo valve according to claim 1, characterized in that the first sealing seat (38) is formed on a first shaft region (46) of the first servo valve piston (30).
3. Servoventil gemäß Anspruch 1, dadurch gekennzeichnet, dass der erste Servoventilkolben (30) einen zweiten Schaftbereich (47) aufweist, an dem ein dem zweiten Servoventilkolben (41) zuweisender kolbenseitiger Anschlag (49) ausgebildet ist.3. Servo valve according to claim 1, characterized in that the first servo valve piston (30) has a second shaft region (47) on which a piston-side stop (49) facing the second servo valve piston (41) is formed.
4. Servoventil gemäß Anspruch 1, dadurch gekennzeichnet, dass der erste Servoventil- kolben (30) einen dritten Schaftbereich (48) aufweist, an welchem der zweite, als Dichthülse ausgebildete Servoventilkolben (41) federbeaufschlagt aufgenommen ist.4. Servo valve according to claim 1, characterized in that the first servo valve piston (30) has a third shaft area (48), on which the second servo valve piston (41), which is designed as a sealing sleeve, is received under spring action.
5. Servoventil gemäß Anspruch 4, dadurch gekennzeichnet, dass der dritte Schaftbereich (48) des ersten Servoventilkolbens (30) in den Arbeitsraum (7) des Druckübersetzers (2) hineinragt.5. Servo valve according to claim 4, characterized in that the third shaft region (48) of the first servo valve piston (30) protrudes into the working space (7) of the pressure intensifier (2).
6. Servoventil gemäß Anspruch 4, dadurch gekennzeichnet, dass der dritte Schaftbereich (48) des ersten Servoventilkolbens (30) eine vom Systemdruck im Arbeitsraum (7) beaufschlagte arbeitsraumseitige Stirnfläche (45) aufweist.6. Servo valve according to claim 4, characterized in that the third shaft region (48) of the first servo valve piston (30) has an end face (45) acted upon by the system pressure in the working space (7).
Servoventil gemäß Anspruch 1, dadurch gekennzeichnet, dass der erste Servoventilkolben (30) einen Durchgangskanal (31) aufweist, an dessen dem Steuerraum (33) zuweisender Seite eine zweite Drosselstelle (32) vorgesehen ist. Servo valve according to Claim 1, characterized in that the first servo valve piston (30) has a through-channel (31), on the side of which facing the control chamber (33) a second throttle point (32) is provided.
8. Servoventil gemäß Anspruch 1, dadurch gekennzeichnet, dass eine den Differenzdruckraum (8) des Druckübersetzers (2) beaufschlagende Leitung sowie den Differenzdruckraum (8) druckentlastende Leitung (28) in einem Servoventilgehäuse (29) des Servoventils (3) an einer Mündungsstelle (40) mündet, die zwischen dem ersten Dichtsitz (38) und dem zweiten Dichtsitz (50) liegt.8. Servo valve according to claim 1, characterized in that a line acting on the differential pressure chamber (8) of the pressure intensifier (2) and the differential pressure chamber (8) pressure-relieving line (28) in a servo valve housing (29) of the servo valve (3) at an outlet point ( 40) opens out, which lies between the first sealing seat (38) and the second sealing seat (50).
9. Servoventil gemäß Anspruch 1, dadurch gekennzeichnet, dass der zweite Dichtsitz (50) zwischen dem Servoventilgehäuse (29) und dem zweiten Schließkolben (41) als Flachsitz ausgebildet ist.9. Servo valve according to claim 1, characterized in that the second sealing seat (50) between the servo valve housing (29) and the second closing piston (41) is designed as a flat seat.
10. Servoventil gemäß Anspruch 1, dadurch gekennzeichnet, dass der zweite Dichtsitz (50) zwischen dem Servoventilgehäuse (29) und dem zweiten Servoventilkolben (41) als Kegelsitz ausgebildet ist.10. Servo valve according to claim 1, characterized in that the second sealing seat (50) between the servo valve housing (29) and the second servo valve piston (41) is designed as a conical seat.
11. Servoventil gemäß Anspruch 9, dadurch gekennzeichnet, dass der als Flachsitz ausgebildete zweite Dichtsitz (50) zwischen dem Servoventilgehäuse (29) und einer kontu- rierten Kolbenfläche (44) des zweiten Servoventilkolbens (41) gebildet wird. 11. Servo valve according to claim 9, characterized in that the second sealing seat (50) designed as a flat seat is formed between the servo valve housing (29) and a contoured piston surface (44) of the second servo valve piston (41).
EP04738706A 2003-07-31 2004-06-17 Control valve for a fuel injector comprising a pressure exchanger Expired - Fee Related EP1651862B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10335059A DE10335059A1 (en) 2003-07-31 2003-07-31 Switching valve for a fuel injector with pressure booster
PCT/DE2004/001255 WO2005015002A1 (en) 2003-07-31 2004-06-17 Control valve for a fuel injector comprising a pressure exchanger

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EP1651862A1 true EP1651862A1 (en) 2006-05-03
EP1651862B1 EP1651862B1 (en) 2008-10-01

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EP (1) EP1651862B1 (en)
JP (1) JP2007500809A (en)
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WO (1) WO2005015002A1 (en)

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US7216815B2 (en) 2007-05-15
WO2005015002A1 (en) 2005-02-17
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JP2007500809A (en) 2007-01-18
DE10335059A1 (en) 2005-02-17
US20060202140A1 (en) 2006-09-14

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