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
  • F02M61/167—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
  • 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
  • F02M61/04—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series
  • F02M61/08—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series the valves opening in direction of fuel flow
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/101—Piezoelectric or electrostrictive devices with electrical and mechanical input and output, e.g. having combined actuator and sensor parts
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure

Definitions

• the invention relates to a fuel injector according to the preamble of the main claim.
• a fuel injector for fuel injection systems of internal combustion engines is known from DE 198 49 203 AI. It comprises a valve closing body, which cooperates with a valve seat body to form a sealing seat, and a piezoelectric actuator for actuating the valve closing body.
• the piezoelectric actuator comprises piezo layers and one or more temperature compensation layers.
• the temperature compensation layers have a temperature expansion coefficient, the sign of which is opposite to the temperature expansion coefficient of the piezo layers.
• a fuel injection valve for fuel injection systems of internal combustion engines which has a first piezoelectric or magnetostrictive actuator, a valve closing body which can be actuated by the first actuator by means of a valve needle and which cooperates with a valve seat surface to form a sealing seat, and a second piezoelectric or has a magnetostrictive actuator which acts against the first actuator on the valve needle.
• the actuators are arranged one behind the other in the longitudinal direction of the fuel injection valve and are connected to one another by a bearing element which is mounted in a stationary manner in the fuel injection valve.
• a disadvantage of the fuel injector known from DE 198 49 203 AI is that the temperature compensation takes place by means of special layers within the actuator, the material of these temperature compensation layers having an opposite temperature expansion. This leads to problems, particularly in the case of fast dynamic processes, since the different materials behave differently due to the different coefficients of thermal expansion.
• a special actuator with temperature compensation layers must be developed.
• a disadvantage of the fuel injector known from DE 199 18 976 AI is the large overall length caused by the axially offset arrangement of the actuators, which also goes hand in hand with a broadening of the fuel injector, which is caused by the mounting of the bearing plate.
• the fuel injector according to the invention with the characterizing features of the main claim has the advantage that conventional stack actuators or actuators with several separate areas with compensation elements can be controlled by a measuring and control device so that a play compensation for the temperature-related changes in length of the actuator in a simple and inexpensive manner without the use of expensive INVAR materials is made possible.
• Biasing on the measuring element can be achieved by jointly clamping the measuring element in the actuator cartridge.
• measuring element can also be arranged outside the actuator, for example integrated into the actuating element.
• Fig. 1A is a highly schematic, sectional view of a first embodiment, a 's inventively designed fuel injection valve,
• FIG. 1B is a highly schematic, sectional representation of a second exemplary embodiment of a fuel injector designed according to the invention
• 2A shows a schematic view of a stack actuator of the fuel injection valve according to the invention
• 2B is a schematic view of an actuator of the fuel injection valve according to the invention with separate control areas
• 3A shows a schematic illustration of the time profile of the forces acting in the actuator without a compensating actuator
• 3B shows a schematic representation of the time profile of the forces acting in the actuator
• the fuel injection valve 1 is designed as a fuel injection valve 1 for mixture-compressing, spark-ignition internal combustion engines. It is particularly suitable for injecting fuel directly into the combustion chamber of the internal combustion engine.
• the fuel injection valve 1 comprises a housing 2, in which a piezoelectric actuator 3 is arranged.
• the piezoelectric actuator 3 can for example consist of several interconnected piezoelectric layers
• the actuator 3 is encapsulated in an actuator cartridge 4 and is preloaded by a biasing spring 5 clamped between the actuator 3 and the actuator cartridge 4. The encapsulation of the actuator 3 is to protect the
• the actuator 3 which is already preassembled in the actuator cartridge 4 is easier to assemble and additionally protected against damage from mechanical loads during installation.
• the actuator 3 is supported with an outflow-side end 6 on a stamp-shaped actuating body 7.
• a valve needle 8 is arranged on the outflow side of the actuating body 7 and is spaced apart from the actuating body 7 via a compensating gap 9.
• the valve needle 8 has a valve closing body at its downstream end 10
• the fuel injection valve 1 forms a sealing seat.
• the fuel injection valve 1 opens outward.
• valve needle 8 is guided on the outflow side of the compensating gap 9 by two guide elements 18 and 20.
• a return spring 19 is used, which is clamped between the valve needle guide 20 and a disk 21, which is non-positively connected to the valve needle 8.
• the fuel injector 1 has a measuring element 13, which at any point in a bed actuation path, the actuating body 7 and the
• Valve needle 8 includes, between the actuator 3 and the
• Valve closing body 11 is arranged.
• the measuring element 13 is arranged between an end face 14 of the actuator cartridge 4 and an inlet-side end 15 of the actuator 3.
• Measuring element 13 can, however, as shown in Fig. 1B, between the downstream end 6 of the actuator 3 and the
• Actuating body 7 may be arranged so that the biasing spring 5 is supported on the measuring element 13.
• the measuring element 13 can alternatively, as also shown in FIG. 1B, be integrated into the actuating body 7. Furthermore, the actuator 3 can also be encapsulated and biased in different ways, as a result of which the measuring element 13 can be arranged at different points in the power flow. It only has to be ensured that the measuring element 13 is arranged on the inlet side of the compensating gap 9. In order to be able to control the width of the compensation gap 9 formed between the actuating body 7 and the valve needle 8 in such a way that undesired opening phases of the fuel injector 1 due to changes in the length of the actuator 3 due to thermal effects can be avoided and a constant opening stroke of the valve needle 8 can be achieved the measuring element 13 is provided.
• the measuring element 13 measures the forces exerted by the actuator 3.
• the control voltage and the voltage of a compensating actuator 16 can be regulated by a control circuit (not shown further) in such a way that reliable play compensation takes place without impairing the dynamic properties of the actuator 3.
• 2A and 2B two exemplary embodiments for possible actuators 3 are shown.
• 2A shows a stack actuator 3, which consists of individual piezoelectric layers 14.
• One or more of the layers 14 can be designed as compensation layers or in their entirety as a compensation actuator 16 and can be integrated in the stack actuator 3.
• the measuring element 13 is arranged at any point in the stack actuator 3.
• a measuring voltage U M is tapped on one side at the actuator 3, so that the pressure force can be measured.
• the actuator voltage U A is present on the other side of the measuring element 13.
• the compensation actuator 16 can also be designed, for example, in the form of a separate compensation actuator 16.
• the actuator 3 is constructed in its entirety from an opening actuator 17, the compensation actuator 16 and the measuring element 13. Each part can be controlled separately. Lines lying at the same potential, for example the ground lines, can also be brought together for simplification.
• FIG. 3A and 3B illustrate the force F which is exerted by the actuator 3 and measured by the measuring element 13.
• the sole force F ⁇ of the opening actuator 17 which is formed either from the totality of the layers 14 of the stacking actuator 3 according to FIG. 2A acting in the opening direction or from the one-piece compensation actuator 16 according to FIG. 2B, is a function of the time t shown. Due to the high dynamics of the piezoelectric actuators 3, an almost rectangular force curve can be represented, which extends over the opening time ti. A game compensation is not possible.
• 3B shows the combined effect of the opening actuator 17 and the compensation actuator 16.
• the compensating actuator 16 is supplied with a small excitation voltage, through which the compensating actuator 16 expands until the compensating gap 9 is closed.
• the measuring element 13 detects the closed compensation gap 9 by increasing the pressure force acting on the measuring element 13.
• the compensating gap 9 is closed and the movement of the opening actuator 17 is immediately transmitted to the valve needle 8 via the actuating element 7.
• the excitation voltage for the compensation actuator 16 can be maintained during the open phase of the fuel injector 1 or can be switched off to dampen the valve needle 8.
• both excitation voltages are switched off, so that all actuator areas for the next injection cycle return to their idle state.
• the compensation actuator 16 can also be kept live during the entire injection cycle. The play compensation can thus take place continuously, a loss of charge of the compensation actuator can be compensated for by reloading.
• the measuring element 13 checks whether the permissible maximum force of the compensating actuator is not exceeded in order to prevent the fuel injector 1 from opening unintentionally.
• the compensation actuator 16 can be discharged continuously or step by step or can be completely separated from the voltage source.
• Corresponding algorithms of the control circuit take into account the temperature of the fuel injection valve 1, temperature changes, the load state of the internal combustion engine and learned values from previous injection cycles.
• the invention is not limited to the exemplary embodiments shown and can also be used, for example, for magnetostrictive actuators 3, for any construction of measuring elements 13 and for any construction of fuel injection valves 1.

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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 (3)

Publications (1)

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• 2001
  • 2001-12-18 DE DE10162250A patent/DE10162250A1/de not_active Withdrawn
• 2002
  • 2002-11-25 US US10/468,537 patent/US6953158B2/en not_active Expired - Fee Related
  • 2002-11-25 EP EP02790256A patent/EP1458971A1/de not_active Withdrawn
  • 2002-11-25 KR KR1020047009337A patent/KR100935811B1/ko not_active IP Right Cessation
  • 2002-11-25 WO PCT/DE2002/004313 patent/WO2003052260A1/de not_active Application Discontinuation
  • 2002-11-25 JP JP2003553119A patent/JP4272996B2/ja not_active Expired - Fee Related

Non-Patent Citations (1)

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