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
  • F02M51/00—Fuel-injection apparatus characterised by being operated electrically
  • F02M51/06—Injectors peculiar thereto with means directly operating the valve needle
  • F02M51/0603—Injectors peculiar thereto with means directly operating the valve needle using piezoelectric or magnetostrictive operating means
• • 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
  • F02M61/167—Means for compensating clearance or thermal expansion
• • 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
  • F02M2200/70—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger
  • F02M2200/703—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger hydraulic

Definitions

• the invention relates to a fuel injector according to the preamble of claim 1.
• Fuel injectors in which a piezoelectric actuator is coupled to the nozzle needle without the interposition of a control valve are known.
• the object of the invention is to improve the injection behavior of a fuel injector according to the preamble of claim 1.
• the object is in a fuel injector with an injector, which has a high-pressure fuel inlet, which communicates with a central high-pressure fuel source outside the Injektorge- housing and with a pressure chamber within the injector in connection, injected from the acted upon by operating pressure fuel into a combustion chamber of an internal combustion engine
• a nozzle needle which is coupled to an actuator directly by a hydraulic coupler without the interposition of a control valve, is released, the actuator is biased by a defined biasing force acting in the same direction as and greater as the pressure force acting on the actuator at a relatively low operating pressure from the hydraulic coupler.
• the actuator is preferably a piezoactuator.
• the hydraulic coupler serves to translate the stroke and / or force of the actuator.
• the high pressure provided by the high-pressure fuel source operating can vary between a relatively high and a relatively low pressure level and is referred to as operating pressure. Due to the defined bias of the actuator whose response at low operating pressures is significantly improved. At high operating pressures, the biasing force is compensated by the compressive force exerted by the hydraulic coupler on the actuator. This provides the advantage that the bias of the actuator does not adversely affect the required actuator force and the required Aktorhub.
• a preferred embodiment of the fuel injector is characterized in that the biasing force is 500 to 800 newtons. This prestressing force range has proved to be particularly advantageous in the context of the present invention.
• a further preferred embodiment of the fuel injector is characterized in that in that at least one biasing element is biased parallel to the actuator, by which at least a part of the biasing force is applied to the actuator. Also, all of the biasing force may be provided by the biasing member.
• Another preferred embodiment of the fuel injector is characterized in that the actuator is arranged within a hollow biasing element. This has the advantage that only little space is required for the biasing element.
• the biasing element comprises a spring sleeve.
• the spring sleeve is preferably formed from spring steel and provided with a plurality of recesses.
• Another preferred embodiment of the fuel injector is characterized in that the biasing element is biased between two cover plates of the actuator to train. Consequently, the actuator is stressed by the biasing element between the cover plates to pressure, so compressed.
• a further preferred embodiment of the fuel injector is characterized in that the hydraulic coupler comprises a coupler piston, which is biased by at least one biasing element or a further biasing member against the actuator, through which at least a part of - A -
• the coupler piston defines on one side a coupler space which is bounded on the opposite side of the nozzle needle.
• the coupler space can also be subdivided into a plurality of sub-coupling spaces, which communicate with one another.
• biasing element or the further biasing element is biased parallel to the coupler piston to pressure.
• This biasing elements is for example a helical compression spring.
• a further preferred exemplary embodiment of the fuel injector is characterized in that the pretensioning element or the further pretensioning element is clamped between the coupling piston and a sealing sleeve which delimits a coupling space.
• the sealing sleeve is guided at one end of the coupler piston.
• Another preferred embodiment of the fuel injector is characterized in that the biasing forces of the biasing member and the further biasing member are coordinated so that the actuator is biased by a defined biasing force that is greater than the compressive force at a relatively low operating pressure of the hydraulic coupler acts on the actuator.
• the attached figure shows a simplified representation of a fuel injector in longitudinal section.
• FIG. 1 shows a longitudinal section of a fuel injector with an injector housing 1.
• the injector housing 1 comprises a nozzle body 2, which projects with its lower free end into a combustion chamber of an internal combustion engine to be supplied with fuel. With its upper end remote from the combustion chamber, the nozzle body 2 is clamped axially against an intermediate body 3 and an injector body 4 by means of a clamping nut (not shown).
• the injector body 4 has substantially the shape of a circular-cylinder jacket-shaped sleeve, whose one end face is closed by the intermediate body 3.
• an axial guide bore 6 is recessed, in which a nozzle needle 8 is guided axially displaceable.
• a sealing edge 10 is formed, which cooperates with a sealing seat or a sealing surface 11 in order to selectively release or close two injection holes 13 and 14 as a function of the position of the nozzle needle 8.
• the nozzle needle tip 9 lifts off from its sealing seat with the sealing edge 10, high-pressure fuel is injected through the injection holes 13 and 14 into the combustion chamber of the internal combustion engine.
• the nozzle needle 8 has a pressure chamber portion 15, followed by an expanding portion 16, which is also referred to as a pressure shoulder.
• the pressure shoulder is arranged in a pressure chamber 17 which is formed between the nozzle needle 8 and the nozzle body 2.
• On the pressure shoulder 16 is followed by a guide portion 18 which is guided in the guide bore 6 movable back and forth.
• a fluid connection is created between the pressure chamber 17 and a nozzle spring chamber 22.
• the nozzle spring chamber 22 is connected via an (not shown) connecting channel with an actuator chamber 25 in connection, which in turn is connected via an inlet channel or a supply line 26 with a high-pressure fuel source in connection, which is also referred to as common rail.
• the fuel injector is actuated by a piezoelectric actuator 30.
• the piezoelectric actuator 30 is coupled with the interposition of a compensating element 31, which is preferably made of ceramic, mechanically coupled to a coupler piston 32 whose combustion chamber near end face bounds a partial coupling space 34 in the axial direction.
• a sealing sleeve 35 which is guided on the coupler piston 32 and biased by a compression spring 36 which is supported on a collar 37 of the coupler piston 32.
• the partial coupling space 34 communicates with a further partial coupling space 40 via a connecting channel 38, which may be equipped with a throttle.
• the guide portion 18 of the nozzle needle 8 is bounded away from the combustion chamber by a collar 44, from which the combustion chamber remote end 45 of the nozzle needle 8 goes out.
• a sealing sleeve 48 is guided, which limits the partial coupling space 40 in the radial direction. Between the sealing sleeve 48 and the collar 44, a nozzle spring 60 is clamped.
• the piezoelectric actuator 30 is disposed between two cover plates 71 and 72, which are held together by a biasing member 74 under bias. As a result, the piezoactuator 30 arranged therebetween is subjected to pressure, that is to say compressed.
• the compression spring 36 which is also referred to as Aktor réellefeder is clamped under pretension between the collar 37 and the sealing sleeve 35, so that it acts alternatively or additionally as a biasing element for the piezoelectric actuator 30.
• the high pressure acting in the fuel injector is also referred to as operating pressure.
• the high pressure acts on the combustion chamber remote end face of the nozzle needle 8.
• the piezoelectric actuator 30 is charged in the idle state of the fuel injector and has its maximum longitudinal extent. To control the Kraftstoffinj ector of the piezoelectric actuator 30 is discharged and retracts it.
• the pressure in the partial Coupling spaces 34 and 40 drops off and the nozzle needle opens, that is, lifts off from its nozzle needle seat.
• a needle stop is provided for limiting the stroke.

Landscapes

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

Applications Claiming Priority (2)

Publications (2)

Family

ID=38441577

Family Applications (1)

Country Status (4)

Family Cites Families (7)

• 2006
  • 2006-03-28 DE DE102006014251A patent/DE102006014251A1/de not_active Withdrawn
• 2007
  • 2007-02-12 AT AT07726342T patent/ATE467759T1/de active
  • 2007-02-12 DE DE502007003736T patent/DE502007003736D1/de active Active
  • 2007-02-12 WO PCT/EP2007/051320 patent/WO2007110267A2/fr active Application Filing
  • 2007-02-12 EP EP07726342A patent/EP2002111B1/fr not_active Not-in-force

Non-Patent Citations (1)

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