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
  • 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
• • 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
  • F02M2200/704—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger hydraulic with actuator and actuated element moving in different directions, e.g. in opposite directions

Definitions

• accumulator injection systems In internal combustion engines, accumulator injection systems (common rail systems) are increasingly being used today, which enable the injection pressure to be adjusted depending on the speed and load.
• common rail systems the pressure generation and the injection process are decoupled from one another in terms of time and location.
• the injection pressure is generated by a separate high pressure pump. This does not necessarily have to be driven synchronously with the injections.
• the pressure can be set independently of the engine speed and the injection quantity.
• pressure-controlled injection valves are replaced by electrically operated injectors, with which the activation time and duration, the start of injection and the injection quantity can be determined. With this type of injection system, there is great freedom with regard to the design of multiple injections or split injections.
• Fuel injectors for accumulator injection systems are usually controlled via solenoid valves or piezo actuators.
• the control valves are relieved of pressure by means of the solenoid valves or the piezo actuators.
• the control chamber has a relief channel, in which a discharge throttle is generally arranged.
• the control chamber for actuating an injection valve member is generally filled via an inlet from the high pressure side, into which an inlet throttle element is embedded.
• the valve closing member which can be, for example, a spherical body or a cone, releases the outlet channel, so that a control volume can flow out of the control chamber.
• the pressure in the control chamber drops and an injection valve member, which is acted upon by the control chamber and is generally of needle-shaped design, opens in the vertical direction. The ascending movement of the injection valve member at the end of the fuel Injector openings are released so that fuel can be injected into the combustion chamber of an internal combustion engine.
• the fuel injectors known from the prior art which can be actuated via solenoid valves or piezo actuators, generally comprise an injector body which is constructed to be pressure-tight and pressure-tight.
• the solenoid valve or the piezo actuator are accommodated outside of this injector body. This lowers the pressure level in the control room via the releases of the drainage channel.
• the needle-shaped injection valve member is actuated indirectly.
• a hydraulic translation device is generally assigned to the piezo actuator, which is arranged outside the valve body, so that its stroke path can be extended, since the piezo crystals arranged in a stack form have only a small change in length when energized.
• the fuel injector is actuated by means of a solenoid valve
• the exact setting of its residual air gap and its armature stroke path are required in order to control the valve valve member closing the outlet channel of the control chamber accordingly precisely, particularly in the high speed range of an internal combustion engine.
• the solution proposed according to the invention provides a particularly compact fuel injector with which direct actuation of a needle-shaped injection valve member is achieved.
• an actuator having a piezocrystal stack is accommodated in a pressure chamber filled with system pressure.
• One end face is connected to a first booster piston which surrounds a second booster piston. closes.
• the second booster piston is formed on the injection valve member.
• the first booster piston and the second booster piston are guided one inside the other, which allows the injection valve member to be guided further alongside a guide section thereof within the nozzle holder. This means that there is no need for a further guide section of the injection valve member.
• the first booster piston is enclosed by a control chamber sleeve, which is pressurized with spring pressure against a flat surface of the nozzle holder.
• the bite edge of the control chamber sleeve is kept permanently in contact with the flat surface of the nozzle holder combination by the compression spring, which ensures that the control chamber is sealed.
• the fuel flows via a nozzle chamber inlet to the nozzle chamber surrounding the injection valve member and from there via an annular gap to the seat of the injection valve member.
• the energization time of the piezo actuator can be reduced, since it does not hold the injection valve member in its firing position in the energized, but in the de-energized state. If the actuator is energized, there is an increase in pressure in the control chamber, as a result of which the second booster piston connected to the injection valve member opens. The injection valve member then releases the injection openings on the combustion chamber side.
• the proposed pressure intensifier for a fuel injector acts as a pressure intensifier with reversal of direction, which causes the injection valve member to open when the actuator is energized and closes the injection valve ghed in the non-energized state.
• the single figure shows a section through the fuel injector proposed according to the invention with direct control of the injection valve member. variants
• the drawing shows a fuel injector 1, which comprises an injector body 2.
• the 1hjector body 2 is connected to a nozzle holder 3 via a nozzle clamping nut 4.
• This arrangement is also called a nozzle holder combination.
• an external thread section 34 is provided on the injector body, and the nozzle clamping nut 4 provided with an internal thread 35 is tightened with a predetermined torque.
• the nozzle clamping nut 4 encloses the nozzle holder 3 with an annular contact surface.
• a high-pressure inlet 6 is provided in the injector body 2 and is connected to a high-pressure storage volume (common rail), which is not shown in the drawing.
• the high-pressure storage volume (common rail) is acted upon by a high-pressure pump, not shown in the drawing.
• the pressure level (system pressure) prevailing in the high-pressure storage volume lies in the range between 1400 bar and 1600 bar.
• a pressure chamber 7, which is formed in the injector body 2 is supplied with fuel 8, which is under system pressure.
• a nozzle chamber inlet 24 branches off from the pressure chamber 7 within the injector body 2, via which the fuel under system pressure is supplied to a nozzle chamber 25 in the nozzle holder 3.
• an actuator 9 is accommodated, which is preferably designed as a piezo actuator and has a piezoelectric crisis stack 10.
• the piezo crystals arranged in stack form undergo a change in length which can be used to actuate the injector valve.
• the piezo actuator 9 is located on an end face 12 of a first booster piston 11.
• the wall of the first booster piston 11 is provided with a compensating bore 13, via which the pressure chamber 7 is connected to a hydraulic chamber 41.
• the first booster piston 11 encloses a second booster piston 19 received on the injection valve head 5.
• the second booster piston 19 also has a recess 32 in which a spring element 17 is embedded, which is supported on a contact surface 37 in the inside of the first booster piston 11.
• the second booster piston 19 and the injection valve member 5 are firmly connected to one another.
• a first annular surface 38 of the second booster piston 19 delimits the hydraulic space 41, while a second annular surface 39 on the underside of the second booster piston 19 delimits a control chamber 18.
• annular surface 20 on the underside of the first Translator piston 11 limited, further limited by the inside 40 of a control chamber sleeve 21 and a rmg-shaped flat surface portion 23 of the nozzle holder 23 abutting the injector body 2.
• a support ring 14 is received, on which a support ring 15 is supported.
• the contact ring 15 forms a contact surface for a compression spring 16, which adjusts the control chamber sleeve 21 to the flat surface 33 of the nozzle holder 3.
• the control chamber sleeve 21 surrounding the first booster piston 11 has a bite edge 22.
• the bite edge 22 is sealingly actuated to the top of the flat surface 23 of the nozzle holder 3.
• the injection valve gHed 5 is received in the nozzle holder 3 within a guide section 31. Underneath the filling section 31 is the nozzle chamber 25, which is supplied with fuel 8 under system pressure through the nozzle chamber inlet 24 from the pressure chamber 7.
• the annular gap 27 extends from the nozzle chamber 25 to the seat 28 of the injection valve element 5 at the end of the nozzle holder 3 on the combustion chamber side. If the injection valve gHed 5 is placed in the seat 28, the injection openings 29 in the combustion chamber of the internal combustion engine are closed; if the seat 28 is open, on the other hand, fuel can be injected into the combustion chamber 30 of the combustion engine via the nozzle chamber inlet 24, the nozzle chamber 25, the annular gap 27 and the then opened injection openings 29.
• control chamber sleeve 21 has a contact surface for the pressure spring 16 on its side facing the compression spring 16.
• the end face of the injector body 2 and the flat surface 23 of the nozzle holder 3 form a butt joint 36 which, enclosed by the nozzle clamping nut 4, represents a pressure-tight seal of the control chamber 18 when the injector body 2 and nozzle holder 3 are screwed together.
• the first booster piston 11 In the de-energized state of the piezo crystal stack 10 of the actuator 9, the first booster piston 11 remains in its rest position due to the pressure equalization between the pressure chamber 7 and the hydraulic chamber 41 via the inlet bore 13. That at the plant Surface 37 abutting spring element 17 acts on the second booster piston 19 in the closing direction, so that the injection valve gHed 5 firmly connected to it is placed in its seat 28. As a result, the injection openings 29 formed at the end of the nozzle holder 3 on the combustion chamber side are closed. No fuel gets into the combustion chamber 30 of the internal combustion engine.
• the spring element 17 is designed in such a way that in the closed state it generates a higher closing force which exceeds the hydraulic opening force acting on the opening step 26 in the pressure chamber 25 when it is pressurized.
• the piezo crystal stack 10 of the actuator 9 If, on the other hand, the piezo crystal stack 10 of the actuator 9 is energized, the individual piezo crystals of the piezo crystal stack 10 assume an elongation, so that a force is generated on the end face 12 of the first booster piston 11, which stands vertically downward.
• the annular surface 20 of the first booster piston 11 that enters the control chamber 18 causes an increase in pressure therein. This pressure increase is transmitted to the second annular surface 39 on the underside of the second booster piston 19.
• the hydraulic force acting on the second annular surface 39 of the second booster piston 19 and the hydraulic force acting on the drain stage 26 in the nozzle chamber 25 exceed the shear force generated by the spring element 17, so that the injection valve member 5 with the second booster piston 19 into the hydraulic chamber 41 entrance.
• the fuel volume displaced from this flows into the drain space 7 via the bore 13.
• the opening injection valve head 5 extends from its seat 28 formed at the end of the nozzle holder 3 on the combustion chamber side, so that the injection openings 29 are released and the fuel under system pressure from the nozzle chamber 25, which flows through the annular gap 27 into which the injection openings 29 flows the combustion chamber 30 can be injected.
• the first booster piston 11 moves into its rest position, as a result of which the pressure prevailing in the control chamber 18 decreases. Due to the decrease in pressure in the control chamber 18, the hydraulic force acting in the opening direction on the second annular surface 39 on the underside of the second booster piston 19 drops, so that the closing movement takes place by the spring element 17 accommodated in the hydraulic chamber 41, while the force acting in the direction of compression the hydraulic force acting on the pressure stage 26 exceeds. As a result, the injection valve gHed 5 firmly connected to the second booster piston 19 is placed in its seat 28 on the combustion chamber side. The injection openings 29 are accordingly closed and no more fuel can be injected into the combustion chamber 30 of the internal combustion engine.
• the first booster piston 11 and the second booster piston 19 represent a pressure booster with reversal of direction.
• the injection valve gHed is opened when the actuator is energized, while when the actuator is de-energized, the injection valve gHed is moved into its closed position.
• the mutually guided booster pistons 11 and 19 form a further guide for the injection valve member, which does not have to be formed in a housing.
• the injection valve member 5 can advantageously be movably guided only within a guide section 31 in the nozzle holder 3.
• the proposed fuel injector Since the actuator 9 is arranged within the pressure space 7 which is subjected to system pressure, the proposed fuel injector has a very compact construction.
• the arrangement of the booster pistons 11 and 19 and of the control chamber sleeve 21 accommodated on the outer surface of the first booster piston 11 advantageously enables simple compensation of bearing tolerances of the injector body 2 and of the control chamber sleeve 21 relative to the flat surface 23 of the nozzle holder 3.
• Another advantage of The configuration of the fuel injector 1 proposed according to the invention can be seen in the fact that the energization time of the actuator 9 can be shortened, which has a favorable effect on its service life.

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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)

Applications Claiming Priority (2)

Publications (2)

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• 2004
  • 2004-02-04 DE DE102004005456A patent/DE102004005456A1/de not_active Withdrawn
  • 2004-12-02 JP JP2006521591A patent/JP4327850B2/ja not_active Expired - Fee Related
  • 2004-12-02 AT AT04804653T patent/ATE390552T1/de not_active IP Right Cessation
  • 2004-12-02 EP EP04804653A patent/EP1714025B1/fr not_active Not-in-force
  • 2004-12-02 DE DE502004006696T patent/DE502004006696D1/de active Active
  • 2004-12-02 WO PCT/EP2004/053230 patent/WO2005075811A1/fr active IP Right Grant
  • 2004-12-02 CN CNB2004800413865A patent/CN100458136C/zh not_active Expired - Fee Related
  • 2004-12-02 US US10/586,869 patent/US7455244B2/en not_active Expired - Fee Related

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