EP3908743B1 - Fuel injector - Google Patents

Fuel injector Download PDF

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Publication number
EP3908743B1
EP3908743B1 EP20700346.8A EP20700346A EP3908743B1 EP 3908743 B1 EP3908743 B1 EP 3908743B1 EP 20700346 A EP20700346 A EP 20700346A EP 3908743 B1 EP3908743 B1 EP 3908743B1
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EP
European Patent Office
Prior art keywords
housing
spring
fuel injector
spring element
injector according
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.)
Active
Application number
EP20700346.8A
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German (de)
French (fr)
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EP3908743A1 (en
Inventor
Henning Kreschel
Bernd Streicher
Gerd Wahr
Mark-Florian Fellmann
Andreas Hielscher
Thomas Schwarz
Thomas Nierychlo
Martin Kessler
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
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Filing date
Publication date
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Publication of EP3908743A1 publication Critical patent/EP3908743A1/en
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Publication of EP3908743B1 publication Critical patent/EP3908743B1/en
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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
    • F02M57/00—Fuel-injectors combined or associated with other devices
    • F02M57/005—Fuel-injectors combined or associated with other devices the devices being sensors
    • 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
    • F02M2200/24—Fuel-injection apparatus with sensors
    • F02M2200/244—Force sensors
    • 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
    • F02M2200/24—Fuel-injection apparatus with sensors
    • F02M2200/247—Pressure sensors

Definitions

  • the invention relates to a fuel injector with a measuring device for at least indirectly detecting the fuel pressure prevailing in a high-pressure chamber of the fuel injector in order to control the opening and closing movement of a nozzle needle of the fuel injector.
  • a fuel injector with the features of the preamble of claim 1 is from DE 10 2015 224 709 A1 known to the applicant.
  • the known fuel injector has a measuring device with a housing that is connected to the fuel injector. Inside the housing there is a piezoelectric element arranged in operative connection with a deformable region of the fuel injector, which is arranged on two opposite end faces in contact with a respective elastically prestressed spring element.
  • the spring elements penetrate or pass through openings in the housing and are used for electrical contacting of the measuring device.
  • an insulating compound is provided in the passage area of the spring elements in the area of the passage openings of the housing.
  • Another generic fuel injector is from the subsequently published DE 10 2018 208 318 A1 known to the applicant.
  • the measuring device has spring elements which bear against the side surfaces of the piezoelectric element to form an electrical contact and which in turn radially surround electrical connection pins or guide elements, the guide elements or connection pins being arranged in contact with the spring elements.
  • the connection pins penetrate through openings formed in the (metallic) housing of the measuring device.
  • an insulating material or the insulating mass is also provided here for electrical insulation of the interior of the measuring device and for avoiding electrical contact between the connection pins and the housing of the measuring device.
  • the fuel injector according to the invention with the features of claim 1 has the advantage that it has a particularly high electrical functional reliability when an axial force is applied to the spring elements or the connection elements in the direction of the housing of the measuring device.
  • the reason for this is that when the spring elements or the connecting elements are subjected to an axial force stress in a direction running in the direction of the housing of the measuring device, in particular when the insulation material is subject to thermal stress, there can be a relative movement of the spring elements on the side surfaces of the piezoelectric element, which existing contact or the cold weld formed there, which enables the electrical signal transmission, can adversely affect.
  • the temperature stress on the insulating compound is due to the fact that the insulating compound is also exposed to high temperature loads or thermal cycling loads due to the installation location of the fuel injector in the area of the engine block of the internal combustion engine and the relatively high temperatures prevailing there.
  • the fuel injector according to the invention with the features of claim 1 therefore has the property that the movement of the spring elements or the connection elements is limited in the direction of the housing, so that there is always a sufficiently good contacting of the side surfaces of the piezoelectric element with the mating surfaces on the spring elements is made possible.
  • the teaching of claim 1 proposes that the insulating mass protrudes beyond an outside of the housing on the side facing away from an interior of the housing, and that the spring element or the connection element outside the housing has a stop area for limiting an axial movement of the spring element or the connection element in the direction of the interior of the housing has a cross section that is at least partially larger than the cross section of the through-opening, the insulating compound being arranged between the stop area and the housing, so that the stop area is arranged at a distance from the outside of the housing.
  • Such a configuration of the fuel injector or the arrangement of the insulating mass in the area of the measuring device and the provision of a stop area on the spring or connection element has the advantage that the between the housing and the stop area on the outside of the housing, direct electrical contacting of the spring element or the connection element with the housing is avoided, and that in addition the axial movement of the spring element or the connection element through the stop area in the axial direction or in the direction to the housing of the measuring device is limited.
  • the insulating compound protrudes laterally beyond the through-opening on the outside of the housing.
  • One Such a design or arrangement of the insulating compound at least ensures that the insulating compound always acts as an (axial) buffer between the housing and the stop area of the spring element or the connection element.
  • the insulating compound protrudes laterally beyond the stop area on the outside of the housing. This development ensures that the insulating compound is located in the entire stop area on the side of the stop area facing the housing.
  • stop area there are also different structural options for forming the stop area on the spring elements or the connection elements. Depending on the geometry, material or application, it can be advantageous, for example, for the stop area to be designed monolithically with the spring element or the connection element. Such a configuration makes it possible in particular to be able to dispense with an additional assembly process of the stop area on the spring element or the connection element, since this is already formed during the production of the spring element or connection element.
  • the stop region may be formed by a component that is separate from the spring element or the connection element and is arranged in a fixed manner on the spring element or the connection element.
  • a component that is separate from the spring element or the connection element and is arranged in a fixed manner on the spring element or the connection element.
  • Such a configuration makes it possible, for example, to form differently configured stop regions using standardized spring elements or connecting elements.
  • the material for the stop area from a different material than the material of the spring element or the connecting element. Materials optimized for the respective function can thus be used for the corresponding elements.
  • a further preferred structural configuration of the measuring device relates to the formation of the spring element and the (electrical) connection element by separate components which are arranged in an operative connection with one another.
  • a first constructive implementation provides that the spring element at least partially surrounds the particularly pin-shaped connection element arranged within the housing parallel to the side surface of the piezoelectric element in a plane running perpendicular to a longitudinal axis of the connection element.
  • the spring element is designed to be elastically deformable in order to generate the contact force acting on the side surface of the piezoelectric element in a direction running parallel to the side surface or perpendicular to the surface of the deformation region, so that the deformation causes a Movement of a contact portion or a contact area of the spring element can be achieved in the direction of the side surface of the piezoelectric element.
  • the spring element is designed as a spiral spring with an elastically deformable deformation section and two guide sections, preferably arranged on the front end areas of the spiral spring, with the two guide sections surrounding the connecting element at least in certain areas and extending in the direction of the longitudinal axis of the Connecting element are arranged slidably along the connecting element.
  • such a spiral spring is advantageously designed as a stamped/bent part.
  • the spring element As an alternative structural design of the spring element, it is designed as a compression spring, in particular in the form of a barrel spring. If a barrel spring is used as the spring element, it is provided that its winding surrounds the connecting element at the two front end areas of the barrel spring with a small radial gap. This ensures that the spring element is guided in an optimized manner by the connection element.
  • connection element In order to minimize deflection of the spring element, it can also be provided that the cross section of the connection element is non-circular, in particular rectangular, at least in some areas. This enables a positional orientation of the spring element in relation to the connection element.
  • the spring element interacts at least indirectly with at least one counter-element, which is arranged in the area of the surface of the deformation area.
  • the Indian 1 The fuel injector 10 shown in greatly simplified form is designed as a so-called common rail injector and is used to inject fuel into the combustion chamber (not shown) of an internal combustion engine, in particular a self-igniting internal combustion engine.
  • the fuel injector 10 has an injector housing 11 consisting at least essentially of metal, in particular of a multi-part design, in which at least one, preferably several injection openings 12 for injecting the fuel are arranged on the side facing the combustion chamber of the internal combustion engine.
  • this forms a high-pressure chamber 15 in which a nozzle needle 16 serving as an injection member is arranged such that it can be lifted in the direction of the double arrow 17.
  • this forms a sealing seat together with the inner wall of the high-pressure chamber 15 or the injector housing 11, so that the injection openings 12 are at least indirectly closed in such a way that the injection of fuel from the High-pressure chamber 15 is avoided in the combustion chamber of the internal combustion engine.
  • the nozzle needle 16 In the other position, not shown, of the nozzle needle 16 lifted from the sealing seat, it releases the injection openings 12 for injecting the fuel into the combustion chamber of the internal combustion engine.
  • the movement of the nozzle needle 16, in particular for releasing the injection openings 12, takes place in a manner known per se by means of an actuator, not shown, which can be controlled via a voltage supply line 18 by a control device of the internal combustion engine.
  • the actuator can in particular be a magnet actuator or else a piezo actuator.
  • the high-pressure chamber 15 is supplied with fuel at high pressure (system pressure) via a supply bore 19 which is arranged inside the injector housing 11 or is formed in components of the fuel injector 10 and which is in particular eccentric to the longitudinal axis 21 of the injector housing 11 in an edge region of the fuel injector 10, at least in the Substantially parallel to the longitudinal axis 21 runs.
  • the supply hole 19 is also connected to a fuel line 22 via a fuel connection piece (not shown), which in turn is coupled to a fuel reservoir 25 (rail).
  • a depression 24 in the form of a blind hole is formed in its outer wall 23, for example, so that the wall thickness of the injector housing 11 in the area of the depression 24 is reduced.
  • the injector housing 11 can also have a flattened area, in the area of which the wall thickness of the injector housing 11 is reduced.
  • the planar base 26 of the depression 24 forms part of a deformation area 27 .
  • the fuel pressure currently prevailing in the supply bore 19 also acts in the injector housing 11 on the side facing away from the depression 24 .
  • the wall section 29 of the injector housing 11 on the side facing the recess 24 acts as a deformation area 27 in the manner of an elastic Deformable membrane, the deformation, which forms as a bulge, is greater, the higher the instantaneous fuel pressure in the supply bore 19 is.
  • the fuel injector 10 has a measuring device 30 to detect the time profile of the fuel pressure in the supply bore 19 and thus also in the high-pressure chamber 15, which is used as an indication of the current position of the nozzle needle 16 for controlling the nozzle needle 16.
  • Measuring device 30 includes a sensor element 32 designed as a piezo element 31.
  • the 2 and 3 show a first embodiment of the measuring device 30.
  • the measuring device 30 has a cup-shaped or cup-shaped housing 35, preferably made of metal, which has a flange section 37 running radially around a longitudinal axis 36 of the housing 35.
  • the housing 35 and thus the measuring device 30 can be cohesively connected to the base 26 of the depression 24 on the fuel injector 10 via the flange section 37, in particular by means of a laser beam weld.
  • the piezo element 31 by means of four example, in which 3 recognizable holding elements 38 were added to the housing 35 under pretension.
  • the piezoelectric element 31, which is constructed in several layers in a known manner, is arranged in overlap with the deformation area 27, the deformation area 27 having an in the 2 recognizable transmission element 40, which is plate-shaped, is arranged in operative connection with the piezoelectric element 31.
  • the end face of the piezoelectric element 31 facing away from the transmission element 40 bears against a base 42 of the interior of the housing 35 .
  • the piezoelectric element 31 When the deformation area 27 deforms, the piezoelectric element 31 generates electrical voltages that are transmitted to a control device via two pin-shaped connection pins 44, 46 that traverse the housing 35 in the area of through-openings 48 and are electrically insulated from the housing 35 by an insulating compound 50 (not shown) about in the 1 recognizable lines 51 forwarded.
  • the through-openings 48 are, for example, purely cylindrical on the side facing away from the interior 47 of the housing 35 or the piezoelectric element 31 and have a conical section 52 in the direction of the piezoelectric element 31, the cross section of which is reduced compared to the aforementioned cylindrical section.
  • the insulating compound 50 which consists in particular of a glass material, protrudes in height over an outer side 53 of the housing 35 or protrudes from the area of the through-opening 48 .
  • different arrangements of the insulating compound 50 are shown for the connection pins 44 and 46 , although preferably only one of the two embodiments shown is used on a housing 35 in each case.
  • the insulating compound 50 forms a bead 55 in the area above the outside 53 of the housing 35 .
  • the connection pin 44 also has a stop area 56 which is formed integrally or monolithically on the connection pin 44 .
  • This stop area 56 which is designed, for example, in the form of a plate or collar on the connection pin 44, runs essentially parallel to the outside 53 on the housing 35, with a distance a being formed between the underside of the stop area 56 and the outside 53 of the housing 35.
  • the cross section of the stop area 56 is dimensioned such that it at least partially, preferably completely, covers the cross section of the through opening 48 in the area of the outer side 53 and is larger than the corresponding cross section of the through opening 48.
  • the The bead 55 ends approximately flush with the outer circumference of the stop area 56, but it can also run somewhat radially inside the stop area 56.
  • the insulating compound 50 is arranged at the connection pin 46 in such a way that it protrudes laterally beyond the cross section of the stop area 56 and bears against a side wall 58 of the stop area 56 . Furthermore, the insulating compound 50 also protrudes somewhat laterally from the through-opening 48 so that it sits there, as it were, on the outside 53 of the housing 35 . The distance a is also formed between the underside of the stop area 56 and the outside 53 of the housing 35 in the case of the connection pin 46 .
  • connection pins 44, 46 form guide areas 60 for the electrical contacting of (metallized) side faces 64 , 66 of the piezoelectric element 31 , in the form of compression springs or barrel springs 62 .
  • the side surfaces 64, 66 are designed in particular as planar or flat side surfaces 64, 66 and run at least essentially perpendicularly to the deformation region 27 or parallel to the longitudinal axis 36 of the housing 35.
  • the barrel spring 62 is characterized by a winding 68 which, viewed in the direction of the longitudinal axis 69 of the connection pins 44, 46, rests directly on the outer circumference of the guide area 60 in the axial end areas of the guide areas 60 or surrounds the guide areas 60 with only a small radial distance.
  • the winding 68 has a guide section 70 there in each case.
  • the winding 68 has a larger diameter in the contact sections 72 used to rest on the side surfaces 64, 66, so that the winding 68 is arranged there at a relatively large radial distance from the guide region 60 of the connection pins 44, 46. It is essential that when the barrel spring 62 is not yet elastically deformed, it has an outer radius in the contact sections 72 that is greater than the distance between the longitudinal axes 69 and the side surfaces 64, 66.
  • the guide sections 70 of the winding 68 facing away from the deformation area 27 also rest axially on the partial section 73 of the connection pins 44, 46, which has an enlarged diameter, and which in this respect form an axial end stop.
  • the guide sections 70 of the winding 68 facing the deformation region 27 interact with an annular counter-element 75 which has a through bore 77, 78 for the connection pins 44, 46 in each case.
  • the counter-element 75 also forms a stop surface 79 in each case for the guide sections 70 of the winding 68 of the barrel spring 62 resting there.
  • the plate-shaped counter-element 75 preferably made of plastic or electrically non-conductive material, is radially surrounded on its outer circumference by an outer wall 81 of the housing 35 at the level of the flange section 37 .
  • the transmission element 40 is accommodated within a central opening 80 of the counter-element 75 .
  • a clamping or press fit is formed between the housing 35, the counter-element 75 and the transmission element 40, which holds or fixes them in the direction of the longitudinal axis 36 when the counter-element 75 or the transmission element 40 is installed in the housing 35.
  • the housing 35 is already provided with the connection pins 44 , 46 . Furthermore, it can also be provided that the piezo element 31 is arranged within the housing 35 . Then the barrel springs 62 on the connection pins 44, 46 in direction A in the 2 axially joined.
  • the direction A runs parallel to the side surface 64, 66 and parallel to the longitudinal axis 69 of the connection pins 44, 46 or perpendicular to the base 26 of the depression 24 or perpendicular to the orientation of the deformation area 27.
  • the contact sections 72 of the winding 68 come into contact with the side surfaces 64, 66 of the piezoelectric element 31 with elastic deformation of the winding 68 in an evasive movement running perpendicularly to the longitudinal axes 69 and make contact with an at least perpendicular to the side surfaces 64, 66 running contact force F the side surfaces 64, 66 electrically.
  • the fact that the barrel springs 62 make contact at their axial end regions on the connection pins 44, 46 also ensures electrical contacting of the side surfaces 64, 66 or of the piezoelectric element 31.
  • a modified measuring device 30a is shown. This differs from the measuring device 30 essentially in that, instead of barrel springs 62, bending springs 85 made of sheet metal and designed as stamped/bent parts are used as spring elements. Furthermore, it is preferably provided that the connection pins 44, 46 in the area of Guide area 60a each have a non-circular, for example each have a square cross-section.
  • the one in the 6 Illustrated development of the spiral spring 85 shows a longitudinal axis 86 and two, arranged on opposite sides of the spiral spring 85, in the non-deformed state strip-shaped guide sections 88, after the deformation or bending, as is to the right of the 6 shown, have a cross section adapted to the cross section of the guide area 60a, so that a form-fitting contact or an arrangement provided with little play on the guide area 60a can be achieved there.
  • a deformation section 89 is provided between the two guide sections 88 .
  • the bending spring 85 has a central, approximately square-shaped contact area 90 which, on the side facing the side surfaces 64, 66, can optionally be provided with a coating 92 to improve the electrical conductivity.
  • the length L of the spiral spring 85 in the non-deformed state is such that according to the representation of Figures 5 and 6 when the bending spring 85 is joined axially and the deformation section 89 is deformed by means of the counter-element 75a, the bending spring 85 is elastically deformed in such a way that the contact area 90 bears against the respective side surface 64, 66 with the contact force F. Furthermore, it is according to the figure 5 provided that the counter-element 75a has a stepped bore 93 which, on the one hand, forms the stop surface 79 for one guide section 70, and, on the other hand, seals the housing 35 to the outside by means of a base section 95.
  • Last is in the 7 a modified embodiment of a measuring device 30b is shown, in which, instead of separate connection pins 44, 46 and thus arranged in an operative connection, barrel springs 62 or bending springs 85, spring elements 96 are used, which at the same time serve as an electrical connection element.
  • the spring elements 96 it is provided that the stop regions 97 are designed, for example, as separate components from the spring elements 96 and are connected to them, for example by a laser weld connection or the like, in order to form axial stop surfaces for the insulating compound 50.
  • the spring elements 96 have, in particular, a rectangular cross section, while the outer shape of the stop regions 97 can be round, for example.
  • the fuel injector 10 described so far or the measuring device 30, 30a, 30b can be altered or modified in many ways without deviating from the idea of the invention

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

Description

Technisches Gebiettechnical field

Die Erfindung betrifft einen Kraftstoffinjektor mit einer Messeinrichtung zur zumindest mittelbaren Erfassung des in einem Hochdruckraum des Kraftstoffinjektors herrschenden Kraftstoffdrucks zur Steuerung der Öffnungs- bzw. Schließbewegung einer Düsennadel des Kraftstoffinjektors.The invention relates to a fuel injector with a measuring device for at least indirectly detecting the fuel pressure prevailing in a high-pressure chamber of the fuel injector in order to control the opening and closing movement of a nozzle needle of the fuel injector.

Stand der TechnikState of the art

Ein Kraftstoffinjektor mit den Merkmalen des Oberbegriffs des Anspruchs 1 ist aus der DE 10 2015 224 709 A1 der Anmelderin bekannt. Der bekannte Kraftstoffinjektor weist eine Messeinrichtung mit einem Gehäuse auf, das mit dem Kraftstoffinjektor verbunden ist. Innerhalb des Gehäuses ist ein in Wirkverbindung mit einem deformierbaren Bereich des Kraftstoffinjektors angeordnetes Piezoelement vorgesehen, das an zwei gegenüberliegenden Stirnseiten in Anlagekontakt mit jeweils einem elastisch vorgespannten Federelement angeordnet ist. Die Federelemente durchdringen bzw. durchsetzen Durchgangsöffnungen des Gehäuses und dienen der elektrischen Kontaktierung der Messeinrichtung. Für die Funktion der Messeinrichtung ist es wesentlich, dass zum einen der Innenraum des Gehäuses der Messeinrichtung gegenüber äußeren Medien, insbesondere Feuchtigkeit, geschützt angeordnet ist, und dass darüber hinaus die Federelemente gegenüber dem aus Metall bestehenden Gehäuse elektrisch isoliert sind. Hierzu ist im Durchtrittsbereich der Federelemente im Bereich der Durchgangsöffnungen des Gehäuses eine Isolationsmasse vorgesehen.A fuel injector with the features of the preamble of claim 1 is from DE 10 2015 224 709 A1 known to the applicant. The known fuel injector has a measuring device with a housing that is connected to the fuel injector. Inside the housing there is a piezoelectric element arranged in operative connection with a deformable region of the fuel injector, which is arranged on two opposite end faces in contact with a respective elastically prestressed spring element. The spring elements penetrate or pass through openings in the housing and are used for electrical contacting of the measuring device. For the function of the measuring device, it is essential that the interior of the housing of the measuring device is protected against external media, particularly moisture, and that the spring elements are electrically insulated from the metal housing. For this purpose, an insulating compound is provided in the passage area of the spring elements in the area of the passage openings of the housing.

Ein weiterer gattungsgemäßer Kraftstoffinjektor ist aus der nachveröffentlichten DE 10 2018 208 318 A1 der Anmelderin bekannt. Bei diesem Kraftstoffinjektor weist die Messeinrichtung Federelemente auf, die an den Seitenflächen des Piezoelements zur Ausbildung eines elektrischen Kontakts anliegen, und die ihrerseits wiederum elektrische Anschlusspins bzw. Führungselemente radial umgeben, wobei die Führungselemente bzw. Anschlusspins in Anlagekontakt mit den Federelementen angeordnet sind. Die Anschlusspins durchdringen in dem (metallischen) Gehäuse der Messeinrichtung ausgebildete Durchgangsöffnungen. Ähnlich wie bei der zuerst genannten Schrift ist auch hier ein Isolationsstoff bzw. die Isolationsmasse zur elektrischen Isolierung des Innenraums der Messeinrichtung sowie zur Vermeidung eines elektrischen Kontakts zwischen den Anschlusspins und dem Gehäuse der Messeinrichtung vorgesehen.Another generic fuel injector is from the subsequently published DE 10 2018 208 318 A1 known to the applicant. With this fuel injector the measuring device has spring elements which bear against the side surfaces of the piezoelectric element to form an electrical contact and which in turn radially surround electrical connection pins or guide elements, the guide elements or connection pins being arranged in contact with the spring elements. The connection pins penetrate through openings formed in the (metallic) housing of the measuring device. Similar to the document mentioned first, an insulating material or the insulating mass is also provided here for electrical insulation of the interior of the measuring device and for avoiding electrical contact between the connection pins and the housing of the measuring device.

Offenbarung der ErfindungDisclosure of Invention

Der erfindungsgemäße Kraftstoffinjektor mit den Merkmalen des Anspruchs 1 hat den Vorteil, dass er eine besonders hohe elektrische Funktionssicherheit bei einer axialen Kraftbeaufschlagung der Federelemente bzw. der Anschlusselemente in Richtung zum Gehäuse der Messeinrichtung aufweist.The fuel injector according to the invention with the features of claim 1 has the advantage that it has a particularly high electrical functional reliability when an axial force is applied to the spring elements or the connection elements in the direction of the housing of the measuring device.

Hintergrund hierfür ist, dass es bei einer axialen Kraftbeanspruchung der Federelemente bzw. der Anschlusselemente in einer in Richtung des Gehäuses der Messeinrichtung verlaufenden Richtung, insbesondere bei einer Temperaturbeanspruchung des Isolationswerkstoffs, zu einer Relativbewegung der Federelemente an den Seitenflächen des Piezoelements kommen kann, was den dort vorhandenen Anlagekontakt bzw. die dort ausgebildete Kaltschweißverbindung, die die elektrische Signalübertragung ermöglicht, negativ beeinträchtigen kann. Die Temperaturbeanspruchung der Isolationsmasse rührt daher, dass aufgrund des Einbauorts des Kraftstoffinjektors im Bereich des Motorblocks der Brennkraftmaschine und der dort herrschenden relativ hohen Temperaturen auch die Isolationsmasse hohen Temperaturbelastungen oder aber Temperaturwechselbelastungen ausgesetzt ist. Der erfindungsgemäße Kraftstoffinjektor mit den Merkmalen des Anspruchs 1 weist daher die Eigenschaft auf, dass die Bewegung der Federelemente bzw. der Anschlusselemente in Richtung des Gehäuses limitiert ist, sodass stets eine hinreichend gute Kontaktierung der Seitenflächen des Piezoelements mit den Gegenflächen an den Federelementen ermöglicht wird.The reason for this is that when the spring elements or the connecting elements are subjected to an axial force stress in a direction running in the direction of the housing of the measuring device, in particular when the insulation material is subject to thermal stress, there can be a relative movement of the spring elements on the side surfaces of the piezoelectric element, which existing contact or the cold weld formed there, which enables the electrical signal transmission, can adversely affect. The temperature stress on the insulating compound is due to the fact that the insulating compound is also exposed to high temperature loads or thermal cycling loads due to the installation location of the fuel injector in the area of the engine block of the internal combustion engine and the relatively high temperatures prevailing there. The fuel injector according to the invention with the features of claim 1 therefore has the property that the movement of the spring elements or the connection elements is limited in the direction of the housing, so that there is always a sufficiently good contacting of the side surfaces of the piezoelectric element with the mating surfaces on the spring elements is made possible.

Hierzu schlägt es die Lehre des Anspruchs 1 vor, dass die Isolationsmasse eine Außenseite des Gehäuses auf der einem Innenraum des Gehäuses abgewandten Seite überragt, und dass das Federelement oder das Anschlusselement außerhalb des Gehäuses einen Anschlagbereich zur Begrenzung einer Axialbewegung des Federelements oder des Anschlusselements in Richtung des Innenraums Gehäuses mit einem Querschnitt aufweist, der zumindest bereichsweise größer ist als der Querschnitt der Durchgangsöffnung, wobei die Isolationsmasse zwischen dem Anschlagbereich und dem Gehäuse angeordnet ist, sodass der Anschlagbereich in einem Abstand zur Außenseite des Gehäuses angeordnet ist.For this purpose, the teaching of claim 1 proposes that the insulating mass protrudes beyond an outside of the housing on the side facing away from an interior of the housing, and that the spring element or the connection element outside the housing has a stop area for limiting an axial movement of the spring element or the connection element in the direction of the interior of the housing has a cross section that is at least partially larger than the cross section of the through-opening, the insulating compound being arranged between the stop area and the housing, so that the stop area is arranged at a distance from the outside of the housing.

Eine derartige Ausgestaltung des Kraftstoffinjektors bzw. der Anordnung der Isolationsmasse im Bereich der Messeinrichtung und des Vorsehens eines Anschlagbereichs am Feder- bzw. Anschlusselement hat bei einer axialen Beanspruchung bzw. Kraftbeaufschlagung des Federelements bzw. des Anschlusselements in Richtung des Gehäuses den Vorteil, dass durch die zwischen dem Gehäuse und dem Anschlagbereich an der Außenseite des Gehäuses befindliche Isolationsmasse eine direkte elektrische Kontaktierung des Federelements bzw. des Anschlusselements mit dem Gehäuse vermieden wird, und dass zusätzlich die Axialbewegung des Federelements bzw. des Anschlusselements durch den Anschlagbereich in axialer Richtung bzw. in Richtung zum Gehäuse der Messeinrichtung limitiert ist.Such a configuration of the fuel injector or the arrangement of the insulating mass in the area of the measuring device and the provision of a stop area on the spring or connection element has the advantage that the between the housing and the stop area on the outside of the housing, direct electrical contacting of the spring element or the connection element with the housing is avoided, and that in addition the axial movement of the spring element or the connection element through the stop area in the axial direction or in the direction to the housing of the measuring device is limited.

Vorteilhafte Weiterbildungen des erfindungsgemäßen Kraftstoffinjektors sind in den Unteransprüchen aufgeführt.Advantageous developments of the fuel injector according to the invention are listed in the dependent claims.

Hinsichtlich der genauen Anordnung der Isolationsmasse im Bereich der Durchgangsöffnung des Gehäuses bzw. im Bereich zwischen der Außenseite des Gehäuses und dem Anschlagbereich gibt es unterschiedliche Möglichkeiten:
In einer ersten konstruktiven Weiterbildung des allgemeinen Erfindungsgedankens ist es vorgesehen, dass die Isolationsmasse die Durchgangöffnung an der Außenseite des Gehäuses seitlich überragt. Eine derartige Ausgestaltung bzw. Anordnung der Isolationsmasse stellt zumindest sicher, dass die Isolationsmasse immer als (axialer) Puffer zwischen dem Gehäuse und dem Anschlagbereich des Federelements bzw. des Anschlusselements wirkt.With regard to the exact arrangement of the insulating compound in the area of the through opening of the housing or in the area between the outside of the housing and the stop area, there are different options:
In a first structural development of the general idea of the invention, it is provided that the insulating compound protrudes laterally beyond the through-opening on the outside of the housing. One Such a design or arrangement of the insulating compound at least ensures that the insulating compound always acts as an (axial) buffer between the housing and the stop area of the spring element or the connection element.

In einer Weiterbildung des zuletzt gemachten Vorschlags ist es vorgesehen, dass die Isolationsmasse den Anschlagbereich an der Außenseite des Gehäuses seitlich überragt. Diese Weiterbildung stellt sicher, dass sich die Isolationsmasse im gesamten Anschlagbereich auf der dem Gehäuse zugewandten Seite des Anschlagbereichs befindet.In a further development of the last proposal, it is provided that the insulating compound protrudes laterally beyond the stop area on the outside of the housing. This development ensures that the insulating compound is located in the entire stop area on the side of the stop area facing the housing.

Zur Ausbildung des Anschlagbereichs an den Federelementen bzw. den Anschlusselementen gibt es ebenfalls unterschiedliche konstruktive Möglichkeiten. Je nach Geometrie, Material oder Anwendungsfall kann es z.B. vorteilhaft sein, dass der Anschlagbereich monolithisch mit dem Federelement oder dem Anschlusselement ausgebildet ist. Eine derartige Ausgestaltung ermöglicht insbesondere, auf einen zusätzlichen Montageprozess des Anschlagbereichs an dem Federelement oder dem Anschlusselement verzichten zu können, da dieser bereits bei der Fertigung des Federelements bzw. Anschlusselements ausgebildet wird.There are also different structural options for forming the stop area on the spring elements or the connection elements. Depending on the geometry, material or application, it can be advantageous, for example, for the stop area to be designed monolithically with the spring element or the connection element. Such a configuration makes it possible in particular to be able to dispense with an additional assembly process of the stop area on the spring element or the connection element, since this is already formed during the production of the spring element or connection element.

Alternativ ist es jedoch auch denkbar, dass der Anschlagbereich durch ein von dem Federelement oder dem Anschlusselement separates Bauteil gebildet ist, das an dem Federelement oder dem Anschlusselement fixiert angeordnet ist. Eine derartige Ausgestaltung ermöglicht es beispielsweise unter Verwendung standardisierter Federelemente oder Anschlusselemente unterschiedlich ausgebildete Anschlagbereiche auszubilden. Auch ist es denkbar, das Material für den Anschlagbereich aus einem anderen Material auszubilden als das Material des Federelements bzw. des Anschlusselements. Somit lassen sich auf die jeweilige Funktion optimierte Materialien für die entsprechenden Elemente verwenden.Alternatively, however, it is also conceivable for the stop region to be formed by a component that is separate from the spring element or the connection element and is arranged in a fixed manner on the spring element or the connection element. Such a configuration makes it possible, for example, to form differently configured stop regions using standardized spring elements or connecting elements. It is also conceivable to form the material for the stop area from a different material than the material of the spring element or the connecting element. Materials optimized for the respective function can thus be used for the corresponding elements.

Um einerseits das Ausfüllen der Durchgangsöffnung mit der Isolationsmasse zu vereinfachen, und andererseits bei einer Axialbeanspruchung des Federelements bzw. des Anschlusselements in Richtung zum Gehäuse hin einen zusätzlichen axialen Widerstand durch die Isolationsmasse auszubilden, kann es vorgesehen sein, dass der Querschnitt der Durchgangsöffnung in Richtung des Innenraums des Gehäuses einen Abschnitt mit reduziertem Querschnitt aufweist. Dadurch stützt sich die Isolationsmasse sozusagen in axialer Richtung gegen den Bereich des den geringeren Querschnitt aufweisenden Abschnitts der Durchgangsöffnung ab.It can be provided to simplify filling the through-opening with the insulating compound on the one hand and to form an additional axial resistance through the insulating compound when the spring element or the connection element is subjected to axial stress in the direction of the housing be that the cross section of the through hole has a section with a reduced cross section in the direction of the interior of the housing. As a result, the insulating compound is supported in the axial direction, so to speak, against the area of the section of the through-opening that has the smaller cross section.

Eine weitere bevorzugte konstruktive Ausgestaltung der Messeinrichtung betrifft die Ausbildung des Federelements und des (elektrischen) Anschlusselements durch separate, in Wirkverbindung miteinander angeordnete Bauteile. Hierzu sieht es eine erste konstruktive Umsetzung vor, dass das Federelement das innerhalb des Gehäuses parallel zur Seitenfläche des Piezoelements angeordnete, insbesondere stiftförmige Anschlusselement in einer senkrecht zu einer Längsachse des Anschlusselements verlaufenden Ebene zumindest bereichsweise umgibt.A further preferred structural configuration of the measuring device relates to the formation of the spring element and the (electrical) connection element by separate components which are arranged in an operative connection with one another. For this purpose, a first constructive implementation provides that the spring element at least partially surrounds the particularly pin-shaped connection element arranged within the housing parallel to the side surface of the piezoelectric element in a plane running perpendicular to a longitudinal axis of the connection element.

Auch hinsichtlich der konkreten Ausbildung des Federelements gibt es unterschiedliche konstruktive Ausgestaltungen. So ist es in einer ersten Weiterbildung des zuletzt gemachten Vorschlags vorgesehen, dass das Federelement zur Erzeugung der auf die Seitenfläche des Piezoelements wirkenden Anlagekraft in einer parallel zur Seitenfläche bzw. senkrecht zur Oberfläche des Verformungsbereichs verlaufenden Richtung elastisch deformierbar ausgebildet ist, sodass durch die Deformation eine Bewegung eines Anlageabschnitts oder eines Kontaktbereichs des Federelements in Richtung der Seitefläche des Piezoelements erzielbar ist.There are also different structural configurations with regard to the specific design of the spring element. In a first development of the most recent proposal, the spring element is designed to be elastically deformable in order to generate the contact force acting on the side surface of the piezoelectric element in a direction running parallel to the side surface or perpendicular to the surface of the deformation region, so that the deformation causes a Movement of a contact portion or a contact area of the spring element can be achieved in the direction of the side surface of the piezoelectric element.

Für den zuletzt gemachten Vorschlag kann es insbesondere vorgesehen sein, dass das Federelement als Biegefeder mit einem elastisch verformbaren Verformungsabschnitt und zwei, vorzugsweise an stirnseitigen Endbereichen der Biegefeder angeordneten Führungsabschnitten ausgebildet ist, wobei die beiden Führungsabschnitte das Anschlusselement zumindest bereichsweise umgeben und in Richtung der Längsachse des Anschlusselements entlang des Anschlusselements verschiebbar angeordnet sind.For the last proposal made, it can be provided in particular that the spring element is designed as a spiral spring with an elastically deformable deformation section and two guide sections, preferably arranged on the front end areas of the spiral spring, with the two guide sections surrounding the connecting element at least in certain areas and extending in the direction of the longitudinal axis of the Connecting element are arranged slidably along the connecting element.

Insbesondere ist eine derartige Biegefeder in vorteilhafter konstruktiver Ausgestaltung als Stanz-/Biegeteil ausgebildet.In particular, such a spiral spring is advantageously designed as a stamped/bent part.

Als alternative konstruktive Ausgestaltung des Federelements ist dieses als Druckfeder, insbesondere in Form einer Tonnenfeder, ausgebildet. Bei Verwendung einer Tonnenfeder als Federelement ist es vorgesehen, dass deren Wicklung das Anschlusselement an den beiden stirnseitigen Endbereichen der Tonnenfeder mit geringem Radialspalt umgibt. Dadurch ist eine optimierte Führung des Federelements durch das Anschlusselement sichergestellt.As an alternative structural design of the spring element, it is designed as a compression spring, in particular in the form of a barrel spring. If a barrel spring is used as the spring element, it is provided that its winding surrounds the connecting element at the two front end areas of the barrel spring with a small radial gap. This ensures that the spring element is guided in an optimized manner by the connection element.

Um ein Ausweichen des Federelements zu minimieren, kann es darüber hinaus vorgesehen sein, dass der Querschnitt des Anschlusselements zumindest bereichsweise unrund, insbesondere rechteckförmig ausgebildet ist. Dadurch wird eine Lageorientierung des Federelements zum Anschlusselement ermöglicht.In order to minimize deflection of the spring element, it can also be provided that the cross section of the connection element is non-circular, in particular rectangular, at least in some areas. This enables a positional orientation of the spring element in relation to the connection element.

Um die für die Deformation des Federelements in Richtung der Stirnfläche des Piezoelements erforderliche Gegenkraft an dem Federelement zu erzeugen, kann es vorgesehen sein, dass das Federelement mit wenigstens einem Gegenelement zumindest mittelbar zusammenwirkt, das im Bereich der Oberfläche des Verformungsbereichs angeordnet ist.In order to generate the counterforce required for the deformation of the spring element in the direction of the end face of the piezoelectric element on the spring element, it can be provided that the spring element interacts at least indirectly with at least one counter-element, which is arranged in the area of the surface of the deformation area.

Weitere Vorteile, Merkmale und Einzelheiten der Erfindung ergeben sich aus der nachfolgenden Beschreibung bevorzugter Ausführungsbeispiele sowie anhand der Zeichnungen.Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawings.

Kurze Beschreibung der Zeichnungen

Fig. 1
zeigt eine stark vereinfachte, teilweise geschnittene Seitenansicht eines erfindungsgemäßen Kraftstoffinjektors mit einer Messeinrichtung zur zumindest mittelbaren Erfassung des Kraftstoffdrucks im Kraftstoffinjektor,
Fig. 2
einen Längsschnitt im Bereich einer Messeinrichtung des Kraftstoffinjektors bei einer ersten Ausführungsform der Messeinrichtung,
Fig. 3
eine Ansicht in Richtung der Ebene III-III der Fig. 2,
Fig. 4
einen Längsschnitt durch eine zweite Ausführungsform einer Messeinrichtung,
Fig. 5
ein Detail der Fig. 4 in vergrößerter Darstellung im Kontaktierungsbereich eines Federelements zu einem Piezoelement,
Fig. 6
das in den Fig. 4 und 5 verwendete Federelement in einer Abwicklung und in teilweise verformtem Zustand und
Fig. 7
eine zweite Ausführungsform einer Messeinrichtung, bei der die Federelemente gleichzeitig als elektrische Anschlusselemente ausgebildet sind.
Brief description of the drawings
1
shows a greatly simplified, partially sectioned side view of a fuel injector according to the invention with a measuring device for at least indirectly detecting the fuel pressure in the fuel injector,
2
a longitudinal section in the area of a measuring device of the fuel injector in a first embodiment of the measuring device,
3
a view in the direction of the III-III plane 2 ,
4
a longitudinal section through a second embodiment of a measuring device,
figure 5
a detail of 4 in an enlarged view in the contact area of a spring element to a piezo element,
6
that in the 4 and 5 spring element used in a development and in a partially deformed state and
7
a second embodiment of a measuring device, in which the spring elements are designed as electrical connection elements at the same time.

Ausführungsformen der ErfindungEmbodiments of the invention

Gleiche Elemente bzw. Elemente mit gleicher Funktion sind in den Figuren mit den gleichen Bezugsziffern versehen.Identical elements or elements with the same function are provided with the same reference numbers in the figures.

Der in der Fig. 1 stark vereinfacht dargestellte Kraftstoffinjektor 10 ist als sogenannter Common-Rail-Injektor ausgebildet, und dient dem Einspritzen von Kraftstoff in den nicht gezeigten Brennraum einer Brennkraftmaschine, insbesondere einer selbstzündenden Brennkraftmaschine.The Indian 1 The fuel injector 10 shown in greatly simplified form is designed as a so-called common rail injector and is used to inject fuel into the combustion chamber (not shown) of an internal combustion engine, in particular a self-igniting internal combustion engine.

Der Kraftstoffinjektor 10 weist ein zumindest im Wesentlichen aus Metall bestehendes, insbesondere mehrteilig ausgebildetes Injektorgehäuse 11 auf, in dem auf der dem Brennraum der Brennkraftmaschine zugewandten Seite wenigstens eine, vorzugsweise mehrere Einspritzöffnungen 12 zum Einspritzen des Kraftstoffs angeordnet sind. Innerhalb des Injektorgehäuses 11 bildet dieses einen Hochruckraum 15 aus, in dem eine als Einspritzglied dienende Düsennadel 16 in Richtung des Doppelpfeils 17 hubbeweglich angeordnet ist. In der dargestellten, abgesenkten Stellung der Düsennadel 16 bildet diese zusammen mit der Innenwand des Hochdruckraums 15 bzw. des Injektorgehäuses 11 einen Dichtsitz aus, so dass die Einspritzöffnungen 12 zumindest mittelbar verschlossen sind, derart, dass das Einspritzen von Kraftstoff aus dem Hochdruckraum 15 in den Brennraum der Brennkraftmaschine vermieden wird. In der anderen, nicht dargestellten, von dem Dichtsitz abgehobenen Position der Düsennadel 16 gibt diese die Einspritzöffnungen 12 zum Einspritzen des Kraftstoffs in den Brennraum der Brennkraftmaschine frei. Die Bewegung der Düsennadel 16, insbesondere zum Freigeben der Einspritzöffnungen 12, erfolgt auf eine an sich bekannte Art und Weise mittels eines nicht dargestellten Aktuators, der über eine Spannungsversorgungsleitung 18 von einer Steuereinrichtung der Brennkraftmaschine ansteuerbar ist. Bei dem Aktuator kann es sich insbesondere um einen Magnetaktuator oder aber um einen Piezoaktuator handeln.The fuel injector 10 has an injector housing 11 consisting at least essentially of metal, in particular of a multi-part design, in which at least one, preferably several injection openings 12 for injecting the fuel are arranged on the side facing the combustion chamber of the internal combustion engine. Within the injector housing 11, this forms a high-pressure chamber 15 in which a nozzle needle 16 serving as an injection member is arranged such that it can be lifted in the direction of the double arrow 17. In the illustrated, lowered position of the nozzle needle 16, this forms a sealing seat together with the inner wall of the high-pressure chamber 15 or the injector housing 11, so that the injection openings 12 are at least indirectly closed in such a way that the injection of fuel from the High-pressure chamber 15 is avoided in the combustion chamber of the internal combustion engine. In the other position, not shown, of the nozzle needle 16 lifted from the sealing seat, it releases the injection openings 12 for injecting the fuel into the combustion chamber of the internal combustion engine. The movement of the nozzle needle 16, in particular for releasing the injection openings 12, takes place in a manner known per se by means of an actuator, not shown, which can be controlled via a voltage supply line 18 by a control device of the internal combustion engine. The actuator can in particular be a magnet actuator or else a piezo actuator.

Die Versorgung des Hochdruckraums 15 mit unter Hochdruck (Systemdruck) stehendem Kraftstoff erfolgt über eine innerhalb des Injektorgehäuses 11 angeordnete bzw. in Bauteilen des Kraftstoffinjektors 10 ausgebildete Versorgungsbohrung 19, die insbesondere exzentrisch zur Längsachse 21 des Injektorgehäuses 11 in einem Randbereich des Kraftstoffinjektors 10, zumindest im Wesentlichen parallel zur Längsachse 21, verläuft. Die Versorgungsbohrung 19 ist darüber hinaus über einen nicht dargestellten Kraftstoffanschlussstutzen mit einer Kraftstoffleitung 22 verbunden, welche wiederum mit einem Kraftstoffspeicher 25 (Rail) gekoppelt ist.The high-pressure chamber 15 is supplied with fuel at high pressure (system pressure) via a supply bore 19 which is arranged inside the injector housing 11 or is formed in components of the fuel injector 10 and which is in particular eccentric to the longitudinal axis 21 of the injector housing 11 in an edge region of the fuel injector 10, at least in the Substantially parallel to the longitudinal axis 21 runs. The supply hole 19 is also connected to a fuel line 22 via a fuel connection piece (not shown), which in turn is coupled to a fuel reservoir 25 (rail).

In einem von den Einspritzöffnungen 12 bzw. dem Brennraum axial relativ weit beabstandeten Bereich des Injektorgehäuses 11 ist in dessen Außenwand 23 beispielhaft eine sacklochförmige Vertiefung 24 ausgebildet, so dass die Wanddicke des Injektorgehäuses 11 im Bereich der Vertiefung 24 reduziert ist. Ergänzend wird erwähnt, dass anstelle einer sacklochförmigen Vertiefung 24 das Injektorgehäuse 11 auch eine Abflachung aufweisen kann, in deren Bereich die Wanddicke des Injektorgehäuses 11 reduziert ist.In an area of the injector housing 11 that is axially relatively far away from the injection openings 12 or the combustion chamber, a depression 24 in the form of a blind hole is formed in its outer wall 23, for example, so that the wall thickness of the injector housing 11 in the area of the depression 24 is reduced. In addition, it is mentioned that instead of a depression 24 in the form of a blind hole, the injector housing 11 can also have a flattened area, in the area of which the wall thickness of the injector housing 11 is reduced.

Der eben ausgebildete Grund 26 der Vertiefung 24 bildet einen Teil eines Verformungsbereichs 27 aus. Dadurch wirkt der in der Versorgungsbohrung 19 augenblicklich herrschende Kraftstoffdruck auch in dem Injektorgehäuse 11 auf der der Vertiefung 24 abgewandten Seite. Dadurch, dass die Wanddicke des Injektorgehäuses 11 im Bereich der Vertiefung 24 reduziert ist, wirkt der Wandabschnitt 29 des Injektorgehäuses 11 auf der der Vertiefung 24 zugewandten Seite als Verformungsbereich 27 in Art einer elastisch verformbaren Membran, wobei die Verformung, welche sich als Wölbung ausbildet, umso größer ist, je höher der augenblickliche Kraftstoffdruck in der Versorgungsbohrung 19 ist.The planar base 26 of the depression 24 forms part of a deformation area 27 . As a result, the fuel pressure currently prevailing in the supply bore 19 also acts in the injector housing 11 on the side facing away from the depression 24 . Due to the fact that the wall thickness of the injector housing 11 is reduced in the area of the recess 24, the wall section 29 of the injector housing 11 on the side facing the recess 24 acts as a deformation area 27 in the manner of an elastic Deformable membrane, the deformation, which forms as a bulge, is greater, the higher the instantaneous fuel pressure in the supply bore 19 is.

Zur Detektion des zeitlichen Verlaufs des Kraftstoffdrucks in der Versorgungsbohrung 19 und damit auch in dem Hochdruckraum 15, welcher als Indiz für die augenblickliche Stellung der Düsennadel 16 zur Ansteuerung der Düsennadel 16 verwendet wird, weist der Kraftstoffinjektor 10 eine Messeinrichtung 30 auf. Die Messeinrichtung 30 umfasst ein als Piezoelement 31 ausgebildetes Sensorelement 32.The fuel injector 10 has a measuring device 30 to detect the time profile of the fuel pressure in the supply bore 19 and thus also in the high-pressure chamber 15, which is used as an indication of the current position of the nozzle needle 16 for controlling the nozzle needle 16. Measuring device 30 includes a sensor element 32 designed as a piezo element 31.

Die Fig. 2 und 3 zeigen eine erste Ausführungsform der Messeinrichtung 30. Die Messeinrichtung 30 weist ein napf- bzw. becherförmiges, vorzugsweise aus Metall bestehendes Gehäuse 35 auf, das einen radial um eine Längsachse 36 des Gehäuses 35 umlaufenden Flanschabschnitt 37 hat. Über den Flanschabschnitt 37 kann das Gehäuse 35 und somit die Messeinrichtung 30, insbesondere mittels einer Laserstrahlschweißnaht, mit dem Grund 26 der Vertiefung 24 am Kraftstoffinjektor 10 stoffschlüssig verbunden werden.The 2 and 3 show a first embodiment of the measuring device 30. The measuring device 30 has a cup-shaped or cup-shaped housing 35, preferably made of metal, which has a flange section 37 running radially around a longitudinal axis 36 of the housing 35. The housing 35 and thus the measuring device 30 can be cohesively connected to the base 26 of the depression 24 on the fuel injector 10 via the flange section 37, in particular by means of a laser beam weld.

Innerhalb einer Ausnehmung des Gehäuses 35 ist das Piezoelement 31 mittels beispielhaft vier, in der Fig. 3 erkennbarer Halteelemente 38 unter Vorspannung in dem Gehäuse 35 aufgenommen. Das in bekannter Art und Weise mehrschichtig aufgebaute Piezoelement 31 ist in Überdeckung mit dem Verformungsbereich 27 angeordnet, wobei der Verformungsbereich 27 über ein in der Fig. 2 erkennbares Übertragungselement 40, das plattenförmig ausgebildet ist, in Wirkverbindung mit dem Piezoelement 31 angeordnet ist. Die dem Übertragungselement 40 abgewandte Stirnseite des Piezoelements 31 liegt demgegenüber an einem Grund 42 des Innenraums des Gehäuses 35 an.Within a recess of the housing 35, the piezo element 31 by means of four example, in which 3 recognizable holding elements 38 were added to the housing 35 under pretension. The piezoelectric element 31, which is constructed in several layers in a known manner, is arranged in overlap with the deformation area 27, the deformation area 27 having an in the 2 recognizable transmission element 40, which is plate-shaped, is arranged in operative connection with the piezoelectric element 31. In contrast, the end face of the piezoelectric element 31 facing away from the transmission element 40 bears against a base 42 of the interior of the housing 35 .

Bei einer Deformation des Verformungsbereichs 27 werden von dem Piezoelement 31 elektrische Spannungen erzeugt, die über zwei stiftförmige Anschlusspins 44, 46, die das Gehäuse 35 im Bereich von Durchgangsöffnungen 48 durchqueren und die zum Gehäuse 35 durch eine Isolationsmasse 50 elektrisch isoliert sind, an eine Steuereinrichtung (nicht dargestellt) über in der Fig. 1 erkennbare Leitungen 51 weitergeleitet.When the deformation area 27 deforms, the piezoelectric element 31 generates electrical voltages that are transmitted to a control device via two pin-shaped connection pins 44, 46 that traverse the housing 35 in the area of through-openings 48 and are electrically insulated from the housing 35 by an insulating compound 50 (not shown) about in the 1 recognizable lines 51 forwarded.

Die Durchgangsöffnungen 48 sind beispielhaft auf der dem Innenraum 47 des Gehäuses 35 bzw. dem Piezoelement 31 abgewandten Seite rein zylindrisch ausgebildet und weisen in Richtung zum Piezoelement 31 einen kegelförmig ausgebildeten Abschnitt 52 auf, der im Querschnitt gegenüber dem angesprochenen zylindrisch ausgebildeten Abschnitt reduziert ist. Weiterhin ist erkennbar, dass die insbesondere aus einem Glaswerkstoff bestehende Isolationsmasse 50 eine Außenseite 53 des Gehäuses 35 in der Höhe überragt bzw. aus dem Bereich der Durchgangsöffnung 48 herausragt. Dabei sind bei den Anschlusspins 44 und 46 aus Vereinfachungsgründen unterschiedliche Anordnungen der Isolationsmasse 50 gezeigt, wobei jedoch vorzugsweise jeweils nur eine der beiden gezeigten Ausführungsformen an einem Gehäuse 35 angewandt wird.The through-openings 48 are, for example, purely cylindrical on the side facing away from the interior 47 of the housing 35 or the piezoelectric element 31 and have a conical section 52 in the direction of the piezoelectric element 31, the cross section of which is reduced compared to the aforementioned cylindrical section. It can also be seen that the insulating compound 50 , which consists in particular of a glass material, protrudes in height over an outer side 53 of the housing 35 or protrudes from the area of the through-opening 48 . For reasons of simplification, different arrangements of the insulating compound 50 are shown for the connection pins 44 and 46 , although preferably only one of the two embodiments shown is used on a housing 35 in each case.

Bei dem Anschlusspin 44 bildet die Isolationsmasse 50 in dem Bereich oberhalb der Außenseite 53 des Gehäuses 35 eine Wulst 55 aus. Der Anschlusspin 44 weist darüber hinaus einen Anschlagbereich 56 auf, der einstückig bzw. monolithisch an dem Anschlusspin 44 angeformt ist. Dieser Anschlagbereich 56, der beispielhaft plattenförmig bzw. in Form eines Bunds am Anschlusspin 44 ausgebildet ist, verläuft im Wesentlichen parallel zur Außenseite 53 am Gehäuse 35, wobei zwischen der Unterseite des Anschlagbereichs 56 und der Außenseite 53 des Gehäuses 35 ein Abstand a ausgebildet ist. Der Querschnitt des Anschlagbereichs 56 ist derart bemessen, dass dieser zumindest bereichsweise, vorzugsweise vollständig den Querschnitt der Durchgangsöffnung 48 im Bereich der Außenseite 53 überdeckt und größer ist als der entsprechende Querschnitt der Durchgangsöffnung 48. Bei der Ausführungsform der Isolationsmasse 50 an dem Anschlusspin 44 schließt die Wulst 55 in etwa bündig mit dem Außenumfang des Anschlagbereichs 56 ab, er kann jedoch auch radial etwas innerhalb des Anschlagbereichs 56 verlaufen.In the case of the connection pin 44 , the insulating compound 50 forms a bead 55 in the area above the outside 53 of the housing 35 . The connection pin 44 also has a stop area 56 which is formed integrally or monolithically on the connection pin 44 . This stop area 56, which is designed, for example, in the form of a plate or collar on the connection pin 44, runs essentially parallel to the outside 53 on the housing 35, with a distance a being formed between the underside of the stop area 56 and the outside 53 of the housing 35. The cross section of the stop area 56 is dimensioned such that it at least partially, preferably completely, covers the cross section of the through opening 48 in the area of the outer side 53 and is larger than the corresponding cross section of the through opening 48. In the embodiment of the insulating compound 50 on the connection pin 44, the The bead 55 ends approximately flush with the outer circumference of the stop area 56, but it can also run somewhat radially inside the stop area 56.

Demgegenüber ist die Isolationsmasse 50 bei dem Anschlusspin 46 derart angeordnet, dass er den Querschnitt des Anschlagbereichs 56 seitlich überragt und an einer Seitenwand 58 des Anschlagbereichs 56 anliegt. Weiterhin tritt die Isolationsmasse 50 seitlich auch etwas aus der Durchgangsöffnung 48 heraus, so dass er dort quasi auf der Außenseite 53 des Gehäuses 35 aufsitzt. Auch beim Anschlusspin 46 ist zwischen der Unterseite des Anschlagbereichs 56 und der Außenseite 53 des Gehäuses 35 der Abstand a ausgebildet.In contrast, the insulating compound 50 is arranged at the connection pin 46 in such a way that it protrudes laterally beyond the cross section of the stop area 56 and bears against a side wall 58 of the stop area 56 . Furthermore, the insulating compound 50 also protrudes somewhat laterally from the through-opening 48 so that it sits there, as it were, on the outside 53 of the housing 35 . The distance a is also formed between the underside of the stop area 56 and the outside 53 of the housing 35 in the case of the connection pin 46 .

Innerhalb des Gehäuses 35, insbesondere in Höhe des Piezoelements 31, ist die Querschnittsfläche bzw. der Durchmesser der Anschlusspins 44, 46 reduziert, sodass dort die Anschlusspins 44, 46 als Führungselemente wirken. In diesem Bereich bilden die Anschlusspins 44, 46 Führungsbereiche 60 für der elektrischen Kontaktierung von (metallisierten) Seitenflächen 64, 66 des Piezoelements 31 dienenden Federelementen in Form von Druck- bzw. Tonnenfedern 62 aus. Die Seitenflächen 64, 66 sind insbesondere als ebene bzw. flache Seitenflächen 64, 66 ausgebildet und verlaufen zumindest im Wesentlichen senkrecht zum Verformungsbereich 27 bzw. parallel zur Längsachse 36 des Gehäuses 35.Inside the housing 35, in particular at the level of the piezoelectric element 31, the cross-sectional area or the diameter of the connection pins 44, 46 is reduced, so that the connection pins 44, 46 act there as guide elements. In this area, the connection pins 44 , 46 form guide areas 60 for the electrical contacting of (metallized) side faces 64 , 66 of the piezoelectric element 31 , in the form of compression springs or barrel springs 62 . The side surfaces 64, 66 are designed in particular as planar or flat side surfaces 64, 66 and run at least essentially perpendicularly to the deformation region 27 or parallel to the longitudinal axis 36 of the housing 35.

Die Tonnenfeder 62 zeichnet sich durch eine Wicklung 68 aus, die in Richtung der Längsachse 69 des Anschlusspins 44, 46 betrachtet in den axialen Endbereichen der Führungsbereiche 60 jeweils unmittelbar am Außenumfang des Führungsbereichs 60 anliegt bzw. die Führungsbereiche 60 mit lediglich geringem radialen Abstand umgeben. Hierzu weist die Wicklung 68 dort jeweils einen Führungsabschnitt 70 auf. Demgegenüber weist die Wicklung 68 in den zur Anlage an den Seitenflächen 64, 66 dienenden Anlageabschnitten 72 einen größeren Durchmesser auf, sodass die Wicklung 68 dort mit relativ großem radialen Abstand zum Führungsbereich 60 des Anschlusspins 44, 46 angeordnet ist. Wesentlich ist dabei, dass bei noch nicht elastisch deformierter Tonnenfeder 62 diese in den Anlageabschnitten 72 einen Außenradius aufweist, der größer ist als der Abstand der Längsachsen 69 von den Seitenflächen 64, 66.The barrel spring 62 is characterized by a winding 68 which, viewed in the direction of the longitudinal axis 69 of the connection pins 44, 46, rests directly on the outer circumference of the guide area 60 in the axial end areas of the guide areas 60 or surrounds the guide areas 60 with only a small radial distance. For this purpose, the winding 68 has a guide section 70 there in each case. In contrast, the winding 68 has a larger diameter in the contact sections 72 used to rest on the side surfaces 64, 66, so that the winding 68 is arranged there at a relatively large radial distance from the guide region 60 of the connection pins 44, 46. It is essential that when the barrel spring 62 is not yet elastically deformed, it has an outer radius in the contact sections 72 that is greater than the distance between the longitudinal axes 69 and the side surfaces 64, 66.

Die dem Verformungsbereich 27 abgewandten Führungsabschnitte 70 der Wicklung 68 liegen darüber hinaus axial an dem im Durchmesser vergrößerten Teilabschnitt 73 der Anschlusspins 44, 46 an, die diesbezüglich einen axialen Endanschlag ausbilden. Die dem Verformungsbereich 27 zugewandten Führungsabschnitte 70 der Wicklung 68 wirken demgegenüber mit einem ringförmigen Gegenelement 75 zusammen, das jeweils eine Durchgangsbohrung 77, 78 für die Anschlusspins 44, 46 aufweist. Das Gegenelement 75 bildet im Bereich der Durchgangsbohrungen 77, 78 darüber hinaus jeweils eine Anschlagfläche 79 für die dort anliegenden Führungsabschnitte 70 der Wicklung 68 der Tonnenfeder 62 aus.The guide sections 70 of the winding 68 facing away from the deformation area 27 also rest axially on the partial section 73 of the connection pins 44, 46, which has an enlarged diameter, and which in this respect form an axial end stop. In contrast, the guide sections 70 of the winding 68 facing the deformation region 27 interact with an annular counter-element 75 which has a through bore 77, 78 for the connection pins 44, 46 in each case. In the area of the through bores 77, 78, the counter-element 75 also forms a stop surface 79 in each case for the guide sections 70 of the winding 68 of the barrel spring 62 resting there.

Beispielhaft ist das plattenförmige, vorzugsweise aus Kunststoff bzw. elektrisch nichtleitendem Material bestehende Gegenelement 75 an seinem Außenumfang von einer Außenwand 81 des Gehäuses 35 in Höhe des Flanschabschnitts 37 radial umfasst. Weiterhin ist innerhalb einer zentralen Öffnung 80 des Gegenelements 75 das Übertragungselement 40 aufgenommen. Hierbei ist zwischen dem Gehäuse 35, dem Gegenelement 75 und dem Übertragungselement 40 beispielsweise eine Klemm- bzw. Presspassung ausgebildet, die bei einer Montage des Gegenelements 75 bzw. des Übertragungselements 40 in dem Gehäuse 35 diese in Richtung der Längsachse 36 halten bzw. fixieren.For example, the plate-shaped counter-element 75 , preferably made of plastic or electrically non-conductive material, is radially surrounded on its outer circumference by an outer wall 81 of the housing 35 at the level of the flange section 37 . Furthermore, the transmission element 40 is accommodated within a central opening 80 of the counter-element 75 . Here, for example, a clamping or press fit is formed between the housing 35, the counter-element 75 and the transmission element 40, which holds or fixes them in the direction of the longitudinal axis 36 when the counter-element 75 or the transmission element 40 is installed in the housing 35.

Bei der Montage der Messeinrichtung 30 ist das Gehäuse 35 bereits mit den Anschlusspins 44, 46 versehen. Weiterhin kann es auch vorgesehen sein, dass das Piezoelement 31 innerhalb des Gehäuses 35 angeordnet ist. Anschließend werden die Tonnenfedern 62 auf die Anschlusspins 44, 46 in Richtung A in der Fig. 2 axial gefügt. Die Richtung A verläuft dabei parallel zur Seitenfläche 64, 66 sowie parallel zur Längsachse 69 des Anschlusspins 44, 46 bzw. senkrecht zum Grund 26 der Vertiefung 24 bzw. senkrecht zur Ausrichtung des Verformungsbereichs 27. Durch eine entsprechende Dimensionierung der axialen Länge der Tonnenfedern 62 wird diese anschließend beim axialen Fügen des Übertragungselements 40 und des Gegenelements 75 in das Gehäuse 35 axial verkürzt bzw. zusammengepresst. Bei der Montage der Tonnenfedern 62 gelangen die Anlageabschnitte 72 der Wicklung 68 unter elastischer Deformation der Wicklung 68 in einer senkrecht zu den Längsachsen 69 verlaufenden Ausweichbewegung in Kontakt mit den Seitenflächen 64, 66 des Piezoelements 31 und kontaktieren mit einer zumindest senkrecht zu den Seitenflächen 64, 66 verlaufenden Anlagekraft F die Seitenflächen 64, 66 elektrisch. Durch den Anlagekontakt der Tonnenfedern 62 an ihren axialen Endbereichen an den Anschlusspins 44, 46 ist auch eine elektrische Kontaktierung der Seitenflächen 64, 66 bzw. des Piezoelements 31 sichergestellt.When the measuring device 30 is installed, the housing 35 is already provided with the connection pins 44 , 46 . Furthermore, it can also be provided that the piezo element 31 is arranged within the housing 35 . Then the barrel springs 62 on the connection pins 44, 46 in direction A in the 2 axially joined. The direction A runs parallel to the side surface 64, 66 and parallel to the longitudinal axis 69 of the connection pins 44, 46 or perpendicular to the base 26 of the depression 24 or perpendicular to the orientation of the deformation area 27. By appropriate dimensioning of the axial length of the barrel springs 62 these are then axially shortened or compressed when the transmission element 40 and the counter-element 75 are axially joined into the housing 35 . When the barrel springs 62 are installed, the contact sections 72 of the winding 68 come into contact with the side surfaces 64, 66 of the piezoelectric element 31 with elastic deformation of the winding 68 in an evasive movement running perpendicularly to the longitudinal axes 69 and make contact with an at least perpendicular to the side surfaces 64, 66 running contact force F the side surfaces 64, 66 electrically. The fact that the barrel springs 62 make contact at their axial end regions on the connection pins 44, 46 also ensures electrical contacting of the side surfaces 64, 66 or of the piezoelectric element 31.

In der Fig. 4 ist eine abgewandelte Messeinrichtung 30a dargestellt. Diese unterscheidet sich von der Messeinrichtung 30 im Wesentlichen dadurch, dass anstatt von Tonnenfedern 62 als Federelement jeweils aus Blech bestehende, als Stanz-/Biegeteile ausgebildete Biegefedern 85 verwendet werden. Weiterhin ist es vorzugsweise vorgesehen, dass die Anschlusspins 44, 46 im Bereich des Führungsbereichs 60a jeweils einen unrunden, beispielhaft jeweils einen quadratischen Querschnitt aufweisen.In the 4 a modified measuring device 30a is shown. This differs from the measuring device 30 essentially in that, instead of barrel springs 62, bending springs 85 made of sheet metal and designed as stamped/bent parts are used as spring elements. Furthermore, it is preferably provided that the connection pins 44, 46 in the area of Guide area 60a each have a non-circular, for example each have a square cross-section.

Die in der Fig. 6 dargestellte Abwicklung der Biegefeder 85 zeigt eine Längsachse 86 sowie zwei, an gegenüberliegenden Seiten der Biegefeder 85 angeordnete, im nicht verformten Zustand streifenförmige Führungsabschnitte 88, die nach dem Verformen bzw. Umbiegen, wie dies rechts neben der Fig. 6 dargestellt ist, einen den Querschnitt des Führungsbereichs 60a angepassten Querschnitt aufweisen, sodass dort eine formschlüssige Anlage oder eine mit geringem Spiel vorgesehene Anordnung an dem Führungsbereich 60a erzielbar ist. Zwischen den beiden Führungsabschnitten 88 ist ein Verformungsabschnitt 89 vorgesehen. Weiterhin weist die Biegefeder 85 einen mittleren, in etwa quadratisch ausgebildeten Kontaktbereich 90 auf, der auf der den Seitenflächen 64, 66 zugewandten Seite gegebenenfalls mit einer Beschichtung 92 zur Verbesserung der elektrischen Leitfähigkeit versehen sein kann. Die Länge L der Biegefeder 85 im unverformten Zustand ist derart, dass entsprechend der Darstellung der Fig. 5 und 6 bei einem axialen Fügen der Biegefeder 85 und einer Deformation des Verformungsabschnitts 89 mittels des Gegenelements 75a die Biegefeder 85 elastisch deformiert, derart, dass der Kontaktbereich 90 an der jeweiligen Seitenfläche 64, 66 mit der Anlagekraft F anliegt. Weiterhin ist es entsprechend der Fig. 5 vorgesehen, dass das Gegenelement 75a eine Stufenbohrung 93 aufweist, die einerseits die Anschlagfläche 79 für den einen Führungsabschnitt 70 ausbildet, und andererseits durch einen Bodenabschnitt 95 das Gehäuse 35 nach außen hin abdichtet.The one in the 6 Illustrated development of the spiral spring 85 shows a longitudinal axis 86 and two, arranged on opposite sides of the spiral spring 85, in the non-deformed state strip-shaped guide sections 88, after the deformation or bending, as is to the right of the 6 shown, have a cross section adapted to the cross section of the guide area 60a, so that a form-fitting contact or an arrangement provided with little play on the guide area 60a can be achieved there. A deformation section 89 is provided between the two guide sections 88 . Furthermore, the bending spring 85 has a central, approximately square-shaped contact area 90 which, on the side facing the side surfaces 64, 66, can optionally be provided with a coating 92 to improve the electrical conductivity. The length L of the spiral spring 85 in the non-deformed state is such that according to the representation of Figures 5 and 6 when the bending spring 85 is joined axially and the deformation section 89 is deformed by means of the counter-element 75a, the bending spring 85 is elastically deformed in such a way that the contact area 90 bears against the respective side surface 64, 66 with the contact force F. Furthermore, it is according to the figure 5 provided that the counter-element 75a has a stepped bore 93 which, on the one hand, forms the stop surface 79 for one guide section 70, and, on the other hand, seals the housing 35 to the outside by means of a base section 95.

Zuletzt ist in der Fig. 7 eine abgewandelte Ausführungsform einer Messeinrichtung 30b gezeigt, bei der anstelle von separaten Anschlusspins 44, 46 und damit in Wirkverbindung angeordneten Tonnenfedern 62 bzw. Biegefedern 85 Federelemente 96 verwendet werden, die gleichzeitig als elektrisches Anschlusselement dienen. Bei den Federelementen 96 ist es vorgesehen, dass die Anschlagbereiche 97 beispielhaft als separate Bauteile von den Federelementen 96 ausgebildet sind und beispielsweise durch eine Laserschweißverbindung oder ähnliches mit diesen verbunden sind, um axiale Anschlagflächen für die Isolationsmasse 50 auszubilden. Die Federelemente 96 weisen insbesondere einen rechteckförmigen Querschnitt auf, während die Außenform der Anschlagbereiche 97 beispielsweise rund ausgebildet sein kann.Last is in the 7 a modified embodiment of a measuring device 30b is shown, in which, instead of separate connection pins 44, 46 and thus arranged in an operative connection, barrel springs 62 or bending springs 85, spring elements 96 are used, which at the same time serve as an electrical connection element. In the case of the spring elements 96, it is provided that the stop regions 97 are designed, for example, as separate components from the spring elements 96 and are connected to them, for example by a laser weld connection or the like, in order to form axial stop surfaces for the insulating compound 50. The spring elements 96 have, in particular, a rectangular cross section, while the outer shape of the stop regions 97 can be round, for example.

Der soweit beschriebene Kraftstoffinjektor 10 bzw. die Messeinrichtung 30, 30a, 30b kann in vielfältiger Art und Weise abgewandelt bzw. modifiziert werden, ohne vom Erfindungsgedanken abzuweichenThe fuel injector 10 described so far or the measuring device 30, 30a, 30b can be altered or modified in many ways without deviating from the idea of the invention

Claims (14)

  1. Fuel injector (10), in particular common rail injector, having an injector housing (11), in which a high-pressure chamber (15) is formed which can be supplied with pressurized fuel via a supply bore (19) arranged in the injector housing (11), having a measuring device (30; 30a; 30b) for at least indirectly detecting the pressure in the high-pressure chamber (15) or in the supply bore (19), wherein the measuring device (30; 30a; 30b) is designed to detect elastic deformation of a deformation region (27), which is at least indirectly operatively connected to the supply bore (19) or to the high-pressure chamber (15), wherein the measuring device (30; 30a; 30b) has a housing (35) in which a sensor element (32), which is in the form of a piezo element (31) and is operatively connected to the deformation region (27), is arranged, wherein the piezo element (31) is electrically contacted on two side surfaces (64, 66), which are arranged at least substantially perpendicularly to the surface (26) of the deformation region (27), by means of an elastically pretensioned spring element (62; 85; 96) in each case, wherein a contact force (F) of the spring element (62; 85; 96) runs at least substantially perpendicularly to the side surface (64, 66), wherein the spring element (96) or an electrical connection element (44, 46) connected to the spring element (62; 85) passes through the housing (35) in the region of a passage opening (48), and wherein an insulation compound (50) is arranged between the spring element (96) or the connection element (44, 46) and the passage opening (48), characterized
    in that the insulation compound (50) protrudes over an outer side (53) of the housing (35) on the side facing away from an interior space (47) of the housing (35), and in that the spring element (96) or the connection element (44, 46) has, outside the housing (35), a stop region (56; 97) for limiting an axial movement of the spring element (96) or of the connection element (44, 46) in the direction of the interior space (47) of the housing (35) with a cross section which is larger at least in regions than the cross section of the passage opening (48), wherein the insulation compound (50) is arranged between the stop region (56; 97) and the housing (35) such that the stop region (56; 97) is arranged at a distance (a) from the outer side (53) of the housing (35).
  2. Fuel injector according to Claim 1,
    characterized
    in that the insulation compound (50) protrudes laterally over the passage opening (48) on the outer side (53) of the housing (35) in the region of the passage opening (48) .
  3. Fuel injector according to Claim 2,
    characterized
    in that the insulation compound (50) protrudes laterally over the stop region (56; 97) on the outer side (53) of the housing (35).
  4. Fuel injector according to one of Claims 1 to 3,
    characterized
    in that the stop region (56) is formed monolithically with the spring element (96) or the connection element (44, 46).
  5. Fuel injector according to one of Claims 1 to 3,
    characterized
    in that the stop region (97) is formed by a component which is separate from the spring element (96) or the connection element (44, 46) and is fixed to the spring element (96) or to the connection element (44, 46).
  6. Fuel injector according to one of Claims 1 to 5,
    characterized
    in that the cross section of the passage opening (48) has a section (52) of reduced cross section in the direction of the interior space (47) of the housing (35).
  7. Fuel injector according to one of Claims 1 to 6,
    characterized
    in that the spring element (62; 85) surrounds, at least in regions, the, in particular pin-shaped, connection element (44, 46), which is arranged within the housing (35) parallel to the side surface (64, 66) of the piezo element (31), in a plane running perpendicularly to a longitudinal axis (69) of the connection element (44, 46).
  8. Fuel injector according to Claim 7,
    characterized
    in that, in order to produce the contact force (F) acting on the side surface (64, 66) of the piezo element (31), the spring element (62; 85) is designed to be elastically deformable by means of a direction (A) running parallel to the side surface (64, 66) or perpendicularly to the surface (26) of the deformation region (27), and therefore a movement of a contact section (72) or of a contact region (90) of the spring element (62; 85) in the direction of the side surface (64, 66) can be achieved by the deformation.
  9. Fuel injector according to Claim 8,
    characterized
    in that the spring element (85) is in the form of a flexible spring with an elastically deformable deformation section (89) and two guide sections (88), which are preferably arranged on end-face end regions of the flexible spring, wherein the two guide sections (88) surround the connection element (44, 46) at least in regions and are arranged displaceably along the connection element (44, 46) in the direction of the longitudinal axis (69) of the connection element (44, 46) .
  10. Fuel injector according to Claim 9,
    characterized
    in that the bending spring is in the form of a punched/bent part.
  11. Fuel injector according to one of Claims 1 to 7,
    characterized
    in that the spring element (62) is in the form of a compression spring.
  12. Fuel injector according to Claim 11,
    characterized
    in that the spring element (62) is in the form of a barrel spring, the winding (68) of which surrounds the connection element (44, 46) on the two end-face end regions of the barrel spring with little radial play.
  13. Fuel injector according to one of Claims 7 to 12,
    characterized
    in that the cross section of the connection element (44, 46) is non-circular, in particular rectangular, at least in regions.
  14. Fuel injector according to one of Claims 1 to 13,
    characterized
    in that the spring element (62; 85) interacts at least indirectly with at least one counter element (75; 75a) which is arranged in the region of the surface (26) of the deformation region (27).
EP20700346.8A 2019-01-10 2020-01-08 Fuel injector Active EP3908743B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102019200232.3A DE102019200232A1 (en) 2019-01-10 2019-01-10 Fuel injector
PCT/EP2020/050238 WO2020144194A1 (en) 2019-01-10 2020-01-08 Fuel injector

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Publication Number Publication Date
EP3908743A1 EP3908743A1 (en) 2021-11-17
EP3908743B1 true EP3908743B1 (en) 2023-03-29

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EP (1) EP3908743B1 (en)
DE (1) DE102019200232A1 (en)
WO (1) WO2020144194A1 (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102014222811A1 (en) * 2014-11-07 2016-05-12 Robert Bosch Gmbh fuel injector
DE102015224709A1 (en) 2015-12-09 2017-06-14 Robert Bosch Gmbh fuel injector
DE102018208318A1 (en) 2018-05-25 2019-11-28 Robert Bosch Gmbh fuel injector

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DE102019200232A1 (en) 2020-07-16
WO2020144194A1 (en) 2020-07-16

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