EP3159533B1 - Fuel injector - Google Patents
Fuel injector Download PDFInfo
- Publication number
- EP3159533B1 EP3159533B1 EP16188282.4A EP16188282A EP3159533B1 EP 3159533 B1 EP3159533 B1 EP 3159533B1 EP 16188282 A EP16188282 A EP 16188282A EP 3159533 B1 EP3159533 B1 EP 3159533B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- housing
- sensor element
- contact
- fuel injector
- contact elements
- 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.)
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- 239000000446 fuel Substances 0.000 title claims description 44
- 238000001465 metallisation Methods 0.000 claims description 22
- 229910000679 solder Inorganic materials 0.000 claims description 18
- 239000000853 adhesive Substances 0.000 claims description 11
- 230000001070 adhesive effect Effects 0.000 claims description 11
- 238000009413 insulation Methods 0.000 claims description 5
- 230000036316 preload Effects 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims 1
- 230000005489 elastic deformation Effects 0.000 claims 1
- 238000002485 combustion reaction Methods 0.000 description 11
- 238000002347 injection Methods 0.000 description 7
- 239000007924 injection Substances 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 238000003754 machining Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000005476 soldering Methods 0.000 description 2
- 240000001439 Opuntia Species 0.000 description 1
- 235000004727 Opuntia ficus indica Nutrition 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
Images
Classifications
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- 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
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- 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
- F02M2200/242—Displacement sensors
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- 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, in particular a common rail injector, according to the preamble of claim 1.
- a fuel injector according to the preamble of claim 1 is from the post-published DE 10 2015 211186 A1 the applicant known.
- the known fuel injector has a sensor element in the form of a piezoelectric element, which is arranged within a hood-shaped housing, wherein the housing presses the piezoelectric element under axial bias against a deformation region of the injector.
- the piezoelectric element is provided both at the voltage applied to the deformation region and at the voltage applied to the inside of the housing side, each with an insulating layer which completely covers the piezoelectric element.
- two blind holes are formed in the piezoelectric element on the side facing away from the deformation region, which extend to the respective electrode layer.
- the contacting of the electrode layers via two contact elements which are arranged in overlap with the piezoelectric element and penetrate the housing bottom.
- the contact elements are electrically conductively connected to the respective electrode layer via solder joints arranged in the region of the electrode layers.
- the housing In order to design a measuring device which is as compact as possible, comprising the piezoelectric element and the housing, it is desirable for the housing to surround the piezoelement at the circumference of the piezoelectric element with the smallest possible gap. In addition, it is important that no mechanical stress peaks occur during the Axialkraftbeetzstoffung of the piezoelectric element through the housing, due to bumps or the like. arise on the housing and / or the piezoelectric element or the insulating layer.
- This housing consists of a housing bottom, a frame-like housing element fastened on the housing bottom, and a cover element which cooperates with the frame-like housing element and which is arranged displaceably or displaceably axially relative to the frame-like housing element.
- the cover-shaped housing element is moved in the direction of the frame-shaped housing element until the desired preload force is generated.
- the piezoelectric element is supported on the housing bottom on the side facing away from the cover-shaped housing element.
- the electrical contacting of the electrode layers of the piezoelectric element via two, the cover-shaped housing member penetrating, provided with spring portions contact elements, which bear electrically conductive on side surfaces of the piezoelectric element.
- EP 2918819 A1 discloses a fuel injector with a sensor for at least indirectly detecting a pressure in a bore leading the fuel in the injector housing, wherein the sensor is arranged on a component in which the bore is formed.
- the clamping device serves to generate a bias voltage to the piezoelectric element.
- the clamping device is designed in the form of a biasing plate, which is connected by means of at least two clamping screws with arms of the support piece 62. By means of a corresponding screw-in depth of the clamping screws in threaded bores of the carrier piece, the preload force acting on the piezo element can be adjusted continuously.
- the invention has the object, a fuel injector, in particular a common rail injector, according to the preamble of claim 1 in such a way that a minimization of the housing base for receiving the piezoelectric element as simple and accurate housing production is possible, in such a way a planar surface can be produced on the side of the housing facing the piezoelectric element.
- a simplified electrical contacting of the electrode layers of the piezoelectric element via the contact elements is to be made possible.
- the invention is based on the idea to form the housing of at least two elements, wherein the one element is designed as a cover element or as a housing cover, which is in preferably planar contact with the sensor element and on the side facing the sensor element a flat Surface having, and wherein in the cover element, the contact elements are arranged, which contact the sensor element at least indirectly electrically.
- the surface of the lid member By providing a cover element having on the side facing the sensor element, in particular a generally planar surface (without protruding from the surface side walls or the like), it is possible with relatively little effort, the surface of the lid member by grinding o.ä , To provide machining method over its entire surface with the appropriate accuracy or low roughness, so that in the assembled state of the measuring device, the lid member with its sensor element facing surface abuts the piezoelectric element or its insulating layer that no mechanical stress peaks in the transmission of an axial force the sensor element are generated.
- the housing cover cooperates with a sleeve-shaped element of the housing on the deformation region of the injector facing away from the side facing a radially inwardly projecting holding portion, against which the housing cover on the deformation region facing side of the holding portion abuts axially.
- the holding portion thus causes a depression of the housing cover in the direction of the sensor element. Furthermore, it allows such a trained Holding portion, when it is arranged over the entire circumference of the sleeve-shaped element, to seal the interior of the housing.
- the sensor element is designed as a piezoelectric element with a rectangular base area and with at least one piezoceramic layer and two electrode layers and with insulating layers, and that two contact elements are provided, which are arranged in the region of preferably diagonally opposite corner regions of the piezoelectric element in the housing cover and flush with the surface of the housing cover facing the sensor element ,
- Such an arrangement makes it possible to machine the housing cover on the side facing the sensor element together with the contact elements already arranged therein, which are usually connected to the cover element via a glass melting process, in order to form the desired planar surface.
- the housing cover is connected to the sleeve-shaped element (housing frame) by means of a weld seam.
- the contact elements are electrically connected with the interposition of a conductive adhesive or a solder with the metallizations.
- the respective electrode layer in particular by a metallization, preferably up to the level of the lid member facing the end face of the To lead piezoelectric element or its insulating layer. The electrical contact between the metallization and the respective contact element then takes place through the conductive adhesive or the solder.
- the contact elements are arranged in at least partial coverage with the sensor element, and that the sensor element on the contact elements facing side at least in the covering area with the contact elements a recess for the conductive adhesive or the solder has.
- Such an embodiment allows a minimization of the required cover and thus the housing size.
- the contact elements are arranged in complete overlap with the sensor element, and that the sensor element for each contact element in alignment with the contact element has a recess in Has a shape of a blind hole, which extends to the respective electrode layer, and which is filled with solder for electrical connection between the electrode layer and the contact element.
- the electrical contacting of the electrode layers of the piezoelectric element does not necessarily have to take place via a conductive adhesive or a solder layer.
- the contact elements are connected by means of an intermediate element in each case with the metallization or the electrode layer.
- the intermediate element may be formed, for example, as a spring element which is connected to the sensor element and rests with a spring portion against the respective contact element.
- the spring element is connected to the piezoelectric element and the spring portion inevitably gets into electrically conductive contact with the contact element during assembly. For reasons of process reliability, such a procedure may possibly have advantages in comparison to an electrical contacting by means of a solder or a conductive adhesive.
- the intermediate elements are received positively and non-positively in a particular annular support member. This makes it possible to dispense with cohesive connections or a particularly simple and reliable installation.
- a spring element instead of a spring element, however, it may also be provided to form the intermediate element in the form of a connecting wire, in particular a bonding wire.
- the contact elements are arranged out of alignment with the sensor element. This allows easier contacting of the contact elements within the housing.
- the Indian Fig. 1 fuel injector 10 shown greatly simplified 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, which consists essentially of metal and may have 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 in a liftable manner in the direction of the double arrow 17.
- a nozzle needle 16 serving as an injection member is arranged in a liftable manner in the direction of the double arrow 17.
- this forms together with the inner wall of the high-pressure chamber 15 and the injector 11 a sealing seat, so that the injection openings 12 are at least indirectly closed, such that no injection of fuel from the high-pressure chamber 15 in the Combustion chamber of the internal combustion engine sattfindet.
- the nozzle needle 16 In the other, not shown, lifted from the sealing seat position of the nozzle needle 16, this 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 actuated via a voltage supply line 18 by a control device of the internal combustion engine.
- the actuator may in particular be a magnetic actuator or else a piezoactuator.
- the supply bore 19 is also connected via a fuel connection, not shown, with a fuel line 22, which in turn is coupled to a fuel reservoir 25 (rail).
- a blind hole-shaped recess 24 is formed, so that the wall thickness of the injector 11 is reduced in the region of the recess 24.
- the injector housing 11 may also have a flattening, in the region of which the wall thickness of the injector housing 11 is reduced.
- the newly formed base 26 of the recess 24 forms part of a deformation region 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 recess 24. Since the wall thickness of the injector housing 11 is reduced in the region of the recess 24, the wall portion 29 of the injector 11 acts on the side facing the recess 24 as a deformation region 27 in the form of an elastically deformable membrane, the greater the deformation, which forms as a curvature is, the higher the instantaneous fuel pressure in the supply bore 19.
- the fuel injector 10 For detecting 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 instantaneous position of the nozzle needle 16 for driving the nozzle needle 16, the fuel injector 10 has a measuring device 30.
- the measuring device 30 comprises a sensor element 32 designed as a piezo element 31.
- the sensor element 32 which is substantially block-shaped with a rectangular base area (FIG. Fig. 3 ) is formed, in addition to a piezoceramic layer 34 at its top and its bottom in each case an electrode layer 35, 36.
- the electrode layers 35, 36 are formed on opposite sides up to a respective side surface 37, 38 and end on the respective opposite side surface 38, 37 in front of the respective other side surface 38, 37th
- this may not only have one but a plurality of piezoceramic layers 34 arranged parallel to one another, which are each separated from one another by electrode layers 35, 36.
- the electrode layers 35, 36 are in turn formed mutually extended with up to one of the side surfaces 37, 38 and terminate on the other side in front of the corresponding side surface 38, 37th
- the two electrode layers 35, 36 on the side facing away from each of the piezoceramic layer 34 are covered with an electrical insulation layer 41, 42.
- the side surfaces 37, 38 are each equipped with a metallization 39, 40, which is formed for example by dipping.
- the metallization 39, 40 extends after the formation of the same initially over the entire height of the side surfaces 37, 38 and is then provided by a machining with bevels 43 in the region of the side edges on the opposite end faces of the insulating layers 39, 40, so that the metallization 39, 40 before the respective end face of the insulating layer 41, 42 ends.
- the newly formed contact surfaces 44, 45 which are also arranged parallel to each other, in particular by a mechanical machining process, such as grinding, surface-finished and equipped with a relatively low roughness.
- the formation of the contact surfaces 44, 45 by double-plan loops. While one (lower) contact surface 45 rests directly on the base 26 of the deformation region 27 of the injector housing 11, the other (upper) contact surface 44 is arranged in operative connection with a housing cover 47.
- the housing cover 47 is part of a housing 50, which comprises at least one substantially sleeve-shaped housing frame 48 in addition to the housing cover 47.
- the particular metal housing frame 48 is connected in a manner not shown, in particular by a laser weld, with the bottom 26 of the injector 11 tightly connected.
- the housing frame 48 which completely surrounds the sensor element 32 at its circumference, has a side facing away from the injector housing 11 and the base 26, respectively flange-like radially inwardly projecting holding portion 51, on the underside of the housing cover 47 is flush with the top thereof.
- the two contact elements 52, 53 are, for example, each with a in the Fig. 1 schematically shown connecting line 54, 55, which in turn are contacted with a control or evaluation device, not shown.
- the contact elements 52, 53 are, as in particular with reference to the Fig. 3 can be seen, arranged near diagonally opposite corner regions 57, 58 of the sensor element 32. They are arranged inside the housing cover 47 in a glass remelting 59 or electrically insulated from the housing cover 47 which is also in particular likewise made of metal. While the contact elements 52, 53 protrude axially, for example, over the upper side of the housing cover 47, they are flush with the underside 61 of the housing cover 47 facing the contact surface 44 of the insulating layer 41.
- the in the Fig. 4 and 5 illustrated measuring device 30a differs from the measuring device 30 according to the Fig. 2 and 3 in that, during its production process, the sensor element 32a has been machined on the upper side facing the housing cover 47 in the region of the (upper) insulation layer 41, in that the areas of the insulation layer 41 arranged in overlap with the contact elements 52, 53 have been partially removed.
- the metallizations 39, 40 as based on the Fig. 5 it can be seen to provide a region-wise increased thickness in the region of the insulation layer 41.
- the metallizations 39, 40 are then in turn partially removed by a mechanical processing, not shown, such that, corresponding to the Fig.
- an at least approximately uniform thickness of the metallization 39, 40 in the region of the top of the insulating layer 41, 42 is formed.
- Such a configuration of the electrode layer 35, 36 causes between the metallization 39, 40 on the upper side facing the housing cover 47, a gap 65 is formed, which can be filled with the electrically conductive adhesive 63 and the solder 64.
- the in the Fig. 6 and 7 illustrated measuring device 30b with the sensor element 32b is characterized in that the electrical contacting of the electrode layer 35, 36 with the respective contact element 52, 53 by means of an electrically conductive intermediate element 66, 67 takes place.
- the intermediate element 66, 67 is designed in the form of a spring element which has a first contact region 68, which is flat, and which is connected to the respective electrode layer 35, 36 via the metallization 39, 40, for example by means of a solder connection, not shown.
- the intermediate element 66, 67 in each case has a spring section 69 with a second abutment region 71 which, in the assembled state of the housing cover 47, bears against the respective contact element 52, 53 under mechanical prestressing.
- the electrical contacting of the contact element 52, 53 with the intermediate element 67, 68 additionally by means of a soldering or a welded connection.
- the measuring device 30c has a sensor element 32c, in which the base 26 of the deformation region 27 facing (lower) insulating layer 42 is partially removed at two diagonally opposite corner regions. In these corner regions, the metallization 39, 40 is guided around by the side surfaces 37, 38. Between the recessed surface areas and a bridging element 73, a gap 74 is formed, in the region of which the respective metallization 39, 40 is contacted with a bonding wire 75, 76.
- the connection can be made for example by means of an adhesive 63 or a solder 64, or by means of other suitable connection technologies, for example by means of ultrasonic bonding or the like.
- the bonding wire 75, 76 can be guided in a simple manner in the form of an arc against the underside 61 of the housing cover 47 in the region of the contact elements 52, 53 where the bonding wires 75, 76 are connected to the contact elements 52, 53.
- the contact elements 52, 53 are arranged completely within the overlap region with the sensor element 32d.
- the sensor element 32d has in the region of diagonally opposite corner regions 57, 58 in each case a blind hole-shaped recess 78, 79, which is formed up to the level of the respective electrode layer 35, 36.
- This recess 78, 79 is completely filled in particular with a solder 64 in order to electrically connect the electrode layer 35, 36 with the contact element 52, 53.
- the electrode layer 35 does not protrude up to the Recess 78 zoom.
- the contact element 52, 53 has a centrally formed passage opening 81, through which the solder 64 can be metered.
- the gap 65 between the sensor element 32d and the housing frame 48 is minimized.
- the sensor element 32d rests with the interposition of a bridging element 82 at the base 26 of the deformation region 27.
- the in the Fig. 13 illustrated measuring device 30e is based essentially on the measuring device 30c according to the Fig. 8 ,
- the contact elements 52, 53 are each connected by means of a connecting element, for example in the form of a bonding wire 75e, 76e, to the associated metallization 39, 40 of the sensor element 32e by soldering or bonding.
- the sections 83, 84 of the bonding wires 75e, 76e connected to the contact element 52, 53 and the metallization 39, 40 in the region of the contact areas 68e, 71e are parallel to one another and perpendicular to the plane of the drawing Fig.
- the in the Fig. 14 and 15 illustrated measuring device 30f has intermediate elements 66f, 67f in the form of spring elements similar to the measuring device 30b.
- the contact areas 68f, 71f are preferably only under mechanical pretension, ie without the formation of a cohesive connection, against the contact elements 52, 53 or the metallizations 39, 40.
- mechanical preloading force of the intermediate elements 66f, 67f and the positioning of the intermediate elements 66f, 67f these are received in regions within a support ring 90.
- the support ring 90 has in the region of the intermediate elements 66f, 67f slot-like recesses 91, 92, in which of the intermediate elements 66f, 67f transversely projecting tabs 93, 94 are arranged positively and non-positively. Thereby a fixation of the intermediate elements 66f, 67f in the support ring 90 is effected.
- the support ring 90 lies with a first end face partially on the underside of the contact elements 52, 53 and with a second end face on the bridging element 72f. Furthermore, the support ring 90 surrounds the sensor element 32 f with a small radial distance and is accommodated in the sleeve-shaped housing frame 48 with a small radial distance.
- the mode of operation of the sensor elements 32, 32a to 32f is that upon an (elastic) deformation of the deformation region 27 as a result of a pressure change in the supply bore 19 by the respective sensor element 32, 32a to 32f, an electrical voltage signal is generated which is transmitted via the contact elements 52, 53 is transmitted to an evaluation or measurement device, not shown. Due to the voltage signal, it is at least indirectly possible to deduce a position of the nozzle needle 16 in the injector housing 11, this signal serving to actuate the nozzle needle 16.
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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
Die Erfindung betrifft einen Kraftstoffinjektor, insbesondere einen Common-Rail-Injektor, nach dem Oberbegriff des Anspruchs 1.The invention relates to a fuel injector, in particular a common rail injector, according to the preamble of claim 1.
Ein Kraftstoffinjektor nach dem Oberbegriff des Anspruchs 1 ist aus der nachveröffentlichten
Um eine möglichst kompakt bauende Messeinrichtung, bestehend aus dem Piezoelement und dem Gehäuse auszubilden, ist es wünschenswert, dass das Gehäuse das Piezoelement am Umfang des Piezoelements mit möglichst geringem Spalt umgibt. Darüber hinaus ist es wichtig, dass bei der Axialkraftbeaufschlagung des Piezoelements durch das Gehäuse keine mechanischen Spannungsspitzen auftreten, die infolge von Unebenheiten o.ä. an dem Gehäuse und/oder dem Piezoelement bzw. der Isolationsschicht entstehen.In order to design a measuring device which is as compact as possible, comprising the piezoelectric element and the housing, it is desirable for the housing to surround the piezoelement at the circumference of the piezoelectric element with the smallest possible gap. In addition, it is important that no mechanical stress peaks occur during the Axialkraftbeaufschlagung of the piezoelectric element through the housing, due to bumps or the like. arise on the housing and / or the piezoelectric element or the insulating layer.
Während an dem Piezoelement bzw. den Isolationsschichten plane Oberflächen zur Vermeidung von Spannungsspitzen durch Überschleifen relativ einfach erzeugt werden können, ist es bei dem bekannten einteiligen, haubenförmigen Gehäuse schwierig, über den gesamten Öffnungsquerschnitt des Gehäuses mit einfachem Aufwand eine ebene bzw. plane Oberfläche zu erzeugen, da, wie oben erläutert, das Piezoelement zumindest nahezu bis an eine Innenwand des Gehäuses heranreichen soll. Weiterhin ist die elektrische Kontaktierung des Piezoelements durch das Durchführen der Kontaktelemente durch das Gehäuse bis zur jeweiligen Elektrodenschicht des Piezoelements und das Ausbilden der Sacklochbohrungen relativ aufwendig.While planar surfaces can be relatively easily produced on the piezoelectric element or the insulating layers to avoid voltage peaks, it is difficult in the known one-part, hood-shaped housing to produce a flat or planar surface over the entire opening cross section of the housing with a simple outlay because, as explained above, the piezoelectric element should at least almost reach as far as an inner wall of the housing. Furthermore, the electrical contacting of the piezoelectric element by the passage of the contact elements through the housing to the respective electrode layer of the piezoelectric element and the formation of the blind holes is relatively expensive.
Weiterhin ist es aus der nachveröffentlichten
Ausgehend von dem dargestellten Stand der Technik liegt der Erfindung die Aufgabe zugrunde, einen Kraftstoffinjektor, insbesondere einen Common-Rail-Injektor, nach dem Oberbegriff des Anspruchs 1 derart weiterzubilden, dass bei einer Minimierung der Gehäusegrundfläche zur Aufnahme des Piezoelements eine möglichst einfache und genaue Gehäusefertigung ermöglicht wird, derart, dass eine plane Oberfläche auf der dem Piezoelement zugewandten Seite des Gehäuses erzeugt werden kann. Darüber hinaus soll eine vereinfachte elektrische Kontaktierung der Elektrodenschichten des Piezoelements über die Kontaktelemente ermöglicht werden.Based on the illustrated prior art, the invention has the object, a fuel injector, in particular a common rail injector, according to the preamble of claim 1 in such a way that a minimization of the housing base for receiving the piezoelectric element as simple and accurate housing production is possible, in such a way a planar surface can be produced on the side of the housing facing the piezoelectric element. In addition, a simplified electrical contacting of the electrode layers of the piezoelectric element via the contact elements is to be made possible.
Diese Aufgabe wird erfindungsgemäß bei einem Kraftstoffinjektor mit den Merkmalen des Anspruchs 1 gelöst.This object is achieved in a fuel injector with the features of claim 1.
Der Erfindung liegt die Idee zugrunde, das Gehäuse aus wenigstens zwei Elementen auszubilden, wobei das eine Element als Deckelelement bzw. als Gehäusedeckel ausgebildet ist, das bzw. der sich in vorzugsweise flächigem Anlagekontakt mit dem Sensorelement befindet und auf der dem Sensorelement zugewandten Seite eine ebene Oberfläche aufweist, und wobei in dem Deckelelement die Kontaktelemente angeordnet sind, die das Sensorelement zumindest mittelbar elektrisch kontaktieren. Durch das Vorsehen eines Deckelelements, das auf der dem Sensorelement zugewandten Seite insbesondere eine insgesamt gesehen ebene Oberfläche (ohne von der Oberfläche abstehende Seitenwände o.ä.) aufweist, ist es mit relativ geringem Aufwand möglich, die Oberfläche des Deckelelements durch Schleifen o.ä. Bearbeitungsverfahren über dessen gesamte Fläche mit der entsprechenden Genauigkeit bzw. geringen Rauigkeit auszustatten, so dass im montierten Zustand der Messeinrichtung das Deckelelement mit seiner dem Sensorelement zugewandten Oberfläche derart an dem Piezoelement bzw. dessen Isolationsschicht anliegt, dass keine mechanischen Spannungsspitzen bei der Übertragung einer Axialkraft auf das Sensorelement erzeugt werden.The invention is based on the idea to form the housing of at least two elements, wherein the one element is designed as a cover element or as a housing cover, which is in preferably planar contact with the sensor element and on the side facing the sensor element a flat Surface having, and wherein in the cover element, the contact elements are arranged, which contact the sensor element at least indirectly electrically. By providing a cover element having on the side facing the sensor element, in particular a generally planar surface (without protruding from the surface side walls or the like), it is possible with relatively little effort, the surface of the lid member by grinding o.ä , To provide machining method over its entire surface with the appropriate accuracy or low roughness, so that in the assembled state of the measuring device, the lid member with its sensor element facing surface abuts the piezoelectric element or its insulating layer that no mechanical stress peaks in the transmission of an axial force the sensor element are generated.
Um es insbesondere ohne eine zusätzliche stoffschlüssige Verbindung zwischen dem Gehäusedeckel und dem restlichen Gehäuse auf einfache Art und Weise zu ermöglichen, die auf das Sensorelement einwirkende axiale Vorspannkraft zu übertragen, ist es erfindungsgemäß vorgesehen, dass der Gehäusedeckel mit einem hülsenförmigen Element des Gehäuses zusammenwirkt, das auf der dem Verformungsbereich des Injektorgehäuses abgewandten Seite einen radial nach innen ragenden Halteabschnitt aufweist, gegen den der Gehäusedeckel auf der dem Verformungsbereich zugewandten Seite des Halteabschnitts axial anliegt. Der Halteabschnitt bewirkt somit ein Niederdrücken des Gehäusedeckels in Richtung des Sensorelements. Weiterhin ermöglicht es ein derartig ausgebildeter Halteabschnitt, wenn er über den gesamten Umfang des hülsenförmigen Elements angeordnet ist, den Innenraum des Gehäuses abzudichten.In order to make it possible, in particular, without an additional cohesive connection between the housing cover and the rest of the housing in a simple manner, to transmit the axial biasing force acting on the sensor element, it is provided according to the invention that the housing cover cooperates with a sleeve-shaped element of the housing on the deformation region of the injector facing away from the side facing a radially inwardly projecting holding portion, against which the housing cover on the deformation region facing side of the holding portion abuts axially. The holding portion thus causes a depression of the housing cover in the direction of the sensor element. Furthermore, it allows such a trained Holding portion, when it is arranged over the entire circumference of the sleeve-shaped element, to seal the interior of the housing.
Um es zu ermöglichen, dass die Kontaktelemente bereits während der Fertigung bzw. des Ausbildung des Gehäusedeckels montiert werden können, wobei durch eine entsprechende Anordnung der Kontaktelemente gleichzeitig die in der Sensormitte liegende maximale Durchbiegung optimal erfasst werden kann, ist weiter erfindungsgemäß vorgesehen, dass das Sensorelement als Piezoelement mit rechteckförmiger Grundfläche und mit wenigstens einer Piezokeramikschicht und zwei Elektrodenschichten sowie mit Isolationsschichten ausgebildet ist, und dass zwei Kontaktelemente vorgesehen sind, die im Bereich vorzugsweise diagonal gegenüberliegender Eckbereiche des Piezoelements im Gehäusedeckel angeordnet und oberflächenbündig mit der dem Sensorelement zugewandten Oberfläche des Gehäusedeckels angeordnet sind. Eine derartige Anordnung ermöglicht es, den Gehäusedeckel auf der dem Sensorelement zugewandten Seite zusammen mit den bereits darin angeordneten Kontaktelementen, welche üblicherweise über einen Glasschmelzprozess mit dem Deckelelement verbunden sind, insgesamt zu bearbeiten, um die gewünschte ebene Oberfläche auszubilden.In order to make it possible for the contact elements to be already mounted during production or the design of the housing cover, wherein the maximum deflection in the sensor center can be optimally detected by a corresponding arrangement of the contact elements, it is further provided according to the invention that the sensor element is designed as a piezoelectric element with a rectangular base area and with at least one piezoceramic layer and two electrode layers and with insulating layers, and that two contact elements are provided, which are arranged in the region of preferably diagonally opposite corner regions of the piezoelectric element in the housing cover and flush with the surface of the housing cover facing the sensor element , Such an arrangement makes it possible to machine the housing cover on the side facing the sensor element together with the contact elements already arranged therein, which are usually connected to the cover element via a glass melting process, in order to form the desired planar surface.
In alternativer Verbindung zwischen dem Gehäuserahmen und dem Gehäusedeckel kann es vorgesehen sein, dass der Gehäusedeckel mit dem hülsenförmigen Element (Gehäuserahmen) mittels einer Schweißnaht verbunden ist. Eine derartige Ausbildung stellt gleichzeitig eine besonders einfache bzw. gute Abdichtung des Gehäuses sicher.In an alternative connection between the housing frame and the housing cover, it may be provided that the housing cover is connected to the sleeve-shaped element (housing frame) by means of a weld seam. Such a design simultaneously ensures a particularly simple or good sealing of the housing.
In einer besonders einfach ausgebildeten elektrischen Kontaktierung der Elektrodenschichten des Piezoelements mittels Metallisierungen kann es in Weiterbildung des zuletzt genannten Vorschlags vorgesehen sein, dass die Kontaktelemente unter Zwischenlage eines Leitklebers oder eines Lotes mit den Metallisierungen elektrisch verbunden sind. Hierzu ist es lediglich erforderlich, die jeweilige Elektrodenschicht, insbesondere durch eine Metallisierung, vorzugsweise bis in Höhe der dem Deckelelement zugewandten Stirnseite des Piezoelements bzw. deren Isolationsschicht zu führen. Die elektrische Kontaktierung zwischen der Metallisierung und dem jeweiligen Kontaktelement erfolgt dann durch den Leitkleber bzw. das Lot.In a particularly simple electrical contacting of the electrode layers of the piezoelectric element by means of metallization, it can be provided in a development of the last-mentioned proposal that the contact elements are electrically connected with the interposition of a conductive adhesive or a solder with the metallizations. For this purpose, it is only necessary, the respective electrode layer, in particular by a metallization, preferably up to the level of the lid member facing the end face of the To lead piezoelectric element or its insulating layer. The electrical contact between the metallization and the respective contact element then takes place through the conductive adhesive or the solder.
Hierzu ist es in einer auf dem zuletzt genannten Vorschlag basierenden Weiterbildung der Erfindung vorgesehen, dass die Kontaktelemente in zumindest teilweiser Überdeckung mit dem Sensorelement angeordnet sind, und dass das Sensorelement auf der den Kontaktelementen zugewandte Seite zumindest im Überdeckungsbereich mit den Kontaktelementen eine Aussparung für den Leitkleber oder das Lot aufweist. Eine derartig Ausführung ermöglicht eine Minimierung der benötigten Deckel- und somit der Gehäusegröße.For this purpose, it is provided in a development based on the last-mentioned proposal development of the invention that the contact elements are arranged in at least partial coverage with the sensor element, and that the sensor element on the contact elements facing side at least in the covering area with the contact elements a recess for the conductive adhesive or the solder has. Such an embodiment allows a minimization of the required cover and thus the housing size.
In einer alternativen Ausgestaltung bzw. Anordnung der Kontaktelemente, die den Bauraum für das Gehäuse weiter minimiert, ist es vorgesehen, dass die Kontaktelemente in vollständiger Überdeckung mit dem Sensorelement angeordnet sind, und dass das Sensorelement für jedes Kontaktelement in Ausrichtung mit dem Kontaktelement eine Ausnehmung in Form einer Sacklochbohrung aufweist, die bis zur jeweiligen Elektrodenschicht reicht, und die mit Lot zur elektrischen Verbindung zwischen der Elektrodenschicht und dem Kontaktelement ausgefüllt ist.In an alternative embodiment or arrangement of the contact elements, which further minimizes the installation space for the housing, it is provided that the contact elements are arranged in complete overlap with the sensor element, and that the sensor element for each contact element in alignment with the contact element has a recess in Has a shape of a blind hole, which extends to the respective electrode layer, and which is filled with solder for electrical connection between the electrode layer and the contact element.
Die elektrische Kontaktierung der Elektrodenschichten des Piezoelements muss nicht zwangsläufig über einen Leitkleber bzw. eine Lotschicht erfolgen. So ist es in einer alternativen elektrischen Kontaktierung vorgesehen, dass die Kontaktelemente mittels jeweils eines Zwischenelements mit der Metallisierung bzw. der Elektrodenschicht verbunden sind. So kann das Zwischenelement beispielsweise als Federelement ausgebildet sein, das mit dem Sensorelement verbunden ist und mit einem Federabschnitt gegen das jeweilige Kontaktelement anliegt. Eine derartige Ausführungsform hat insbesondere den Vorteil, dass in einem separaten Herstellschritt das Federelement mit dem Piezoelement verbunden wird und der Federabschnitt bei der Montage zwangsläufig in elektrisch leitendem Kontakt mit dem Kontaktelement gerät. Aus Gründen der Prozesssicherheit kann ein derartiges Vorgehen ggf. im Vergleich zu einer elektrischen Kontaktierung mittels eines Lotes oder eines Leitklebers Vorteile aufweisen.The electrical contacting of the electrode layers of the piezoelectric element does not necessarily have to take place via a conductive adhesive or a solder layer. Thus, it is provided in an alternative electrical contacting that the contact elements are connected by means of an intermediate element in each case with the metallization or the electrode layer. Thus, the intermediate element may be formed, for example, as a spring element which is connected to the sensor element and rests with a spring portion against the respective contact element. Such an embodiment has the particular advantage that in a separate manufacturing step, the spring element is connected to the piezoelectric element and the spring portion inevitably gets into electrically conductive contact with the contact element during assembly. For reasons of process reliability, such a procedure may possibly have advantages in comparison to an electrical contacting by means of a solder or a conductive adhesive.
Bei einer weiteren Ausgestaltung zur Befestigung der Zwischenelemente in dem Gehäuse ist es vorgesehen, dass die Zwischenelemente in einem insbesondere ringförmigen Stützelement form- und kraftschlüssig aufgenommen sind. Dadurch ist ein Verzicht auf stoffschlüssige Verbindungen bzw. eine besonders einfache und prozessichere Montage möglich.In a further embodiment for fastening the intermediate elements in the housing, it is provided that the intermediate elements are received positively and non-positively in a particular annular support member. This makes it possible to dispense with cohesive connections or a particularly simple and reliable installation.
Anstelle eines Federelements kann es jedoch auch vorgesehen sein, das Zwischenelement in Form eines Verbindungsdrahts, insbesondere einen Bonddrahts auszubilden.Instead of a spring element, however, it may also be provided to form the intermediate element in the form of a connecting wire, in particular a bonding wire.
Bei den Ausgestaltungen der Erfindung, bei denen die elektrische Kontaktierung der Metallisierungen bzw. der Elektrodenschichten über ein Zwischenelement erfolgt, ist es von Vorteil, wenn die Kontaktelemente außer Deckung mit dem Sensorelement angeordnet sind. Dadurch wird eine einfachere Kontaktierung der Kontaktelemente innerhalb des Gehäuses ermöglicht.In the embodiments of the invention, in which the electrical contacting of the metallizations or the electrode layers takes place via an intermediate element, it is advantageous if the contact elements are arranged out of alignment with the sensor element. This allows easier contacting of the contact elements within the housing.
Weitere Vorteile, Merkmale und Einzelheiten der Erfindung ergeben sich aus der nachfolgenden Beschreibung bevorzugter Ausführungsbeispiele sowie anhand der Zeichnung.Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing.
Diese zeigt in:
- Fig. 1
- eine stark vereinfachte, teilweise geschnittene Seitenansicht eines erfindungsgemäßen Kraftstoffinjektors mit einer Messeinrichtung zur zumindest mittelbaren Verfassung des Kraftstoffdrucks im Kraftstoffinjektor,
- Fig. 2
- einen Längsschnitt durch eine erste Messeinrichtung im Verbindungsbereich zum Kraftstoffinjektor,
- Fig. 3
- eine Draufsicht auf ein Messelement, wie es bei der Messeinrichtung der
Fig. 2 verwendet wird, in Höhe von Kontaktelementen, - Fig. 4
- eine zweite Ausführungsform einer Messeinrichtung im Verbindungsbereich zum Injektorgehäuse im Längsschnitt,
- Fig. 5
- einen Längsschnitt durch ein Piezoelement, wie es bei der Messeinrichtung gemäß
Fig. 4 verwendet wird, nach dem Ausbilden einer Metallisierung, - Fig. 6
- einen Längsschnitt durch eine dritte Ausführungsform einer Messeinrichtung im Verbindungsbereich zum Gehäuse,
- Fig. 7
- eine perspektivische Unteransicht auf die Messeinrichtung gemäß
Fig. 6 , - Fig. 8
- einen Längsschnitt durch eine vierte Ausführungsform der Messeinrichtung im Verbindungsbereich zum Injektorgehäuse,
- Fig. 9
- eine Unteransicht auf einen Teil der Messeinrichtung gemäß
Fig. 8 , - Fig. 10
- eine perspektivische Draufsicht auf ein Piezoelement bei einer fünften Ausführungsform der Messeinrichtung,
- Fig. 11 und Fig. 12
- Längsschnitte in den Ebenen XI-XI und XII-XII der
Fig. 10 bei einer Messeinrichtung unter Verwendung des Piezoelements gemäßFig. 10 , - Fig. 13
- einen Längsschnitt durch eine sechste Messeinrichtung im Verbindungsbereich zum Kraftstoffinjektor,
- Fig. 14
- einen Längsschnitt durch eine siebte Messeinrichtung im Verbindungsbereich zum Kraftstoffinjektor und
- Fig. 15
- einen Querschnitt durch die Messeinrichtung der
Fig. 14 im Bereich eines Stützrings.
- Fig. 1
- a greatly simplified, partially sectioned side view of a fuel injector according to the invention with a measuring device for at least indirect constitution of the fuel pressure in the fuel injector,
- Fig. 2
- a longitudinal section through a first measuring device in the connection region to the fuel injector,
- Fig. 3
- a plan view of a measuring element, as in the measuring device of
Fig. 2 is used, in the amount of contact elements, - Fig. 4
- a second embodiment of a measuring device in the connection region to the injector in longitudinal section,
- Fig. 5
- a longitudinal section through a piezoelectric element, as in the measuring device according to
Fig. 4 is used, after forming a metallization, - Fig. 6
- a longitudinal section through a third embodiment of a measuring device in the connection region to the housing,
- Fig. 7
- a perspective bottom view of the measuring device according to
Fig. 6 . - Fig. 8
- a longitudinal section through a fourth embodiment of the measuring device in the connection region to the injector,
- Fig. 9
- a bottom view of a part of the measuring device according to
Fig. 8 . - Fig. 10
- a perspective top view of a piezoelectric element in a fifth embodiment of the measuring device,
- 11 and FIG. 12
- Longitudinal sections in the planes XI-XI and XII-XII of the
Fig. 10 in a measuring device using the piezoelectric element according toFig. 10 . - Fig. 13
- a longitudinal section through a sixth measuring device in the connection region to the fuel injector,
- Fig. 14
- a longitudinal section through a seventh measuring device in the connection region to the fuel injector and
- Fig. 15
- a cross section through the measuring device of
Fig. 14 in the area of a support ring.
Gleiche Elemente und Elemente mit gleicher Funktion sind in den Figuren mit den gleichen Bezugsziffern versehen.The same elements and elements with the same function are provided in the figures with the same reference numerals.
Der in der
Der Kraftstoffinjektor 10 weist ein im Wesentlichen aus Metall bestehendes, ggf. 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 kein Einspritzen von Kraftstoff aus dem Hochdruckraum 15 in den Brennraum der Brennkraftmaschine sattfindet. 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
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 supply of the high-
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 one of the
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. Da 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 newly formed
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.For detecting the time profile of the fuel pressure in the supply bore 19 and thus also in the high-
Das Sensorelement 32, das im Wesentlichen blockförmig mit rechteckförmiger Grundfläche (
In einer nicht gezeigten Ausführungsform des Sensorelements 32 kann dieses nicht nur eine, sondern mehrere, parallel zueinander angeordnete Piezokeramikschichten 34 aufweisen, die jeweils durch Elektrodenschichten 35, 36 voneinander getrennt sind. Die Elektrodenschichten 35, 36 sind wiederum wechselseitig mit bis zu einer der Seitenflächen 37, 38 verlängert ausgebildet und enden auf der jeweils anderen Seite vor der entsprechenden Seitenfläche 38, 37.In an embodiment, not shown, of the
Darüber hinaus sind die beiden Elektrodenschichten 35, 36 auf der jeweils der Piezokeramikschicht 34 abgewandten Seite mit einer elektrischen Isolationsschicht 41, 42 überdeckt. Die Seitenflächen 37, 38 sind mit jeweils einer Metallisierung 39, 40 ausgestattet, die beispielsweise im Tauchverfahren ausgebildet ist. Die Metallisierung 39, 40 reicht nach dem Ausbilden derselben zunächst über die gesamte Höhe der Seitenflächen 37, 38 und wird anschließend durch eine mechanische Bearbeitung mit Fasen 43 im Bereich der Seitenkanten auf den einander abgewandten Stirnflächen der Isolationsschichten 39, 40 versehen, so dass die Metallisierung 39, 40 vor der jeweiligen Stirnfläche der Isolationsschicht 41, 42 endet.In addition, the two
Die der Piezokeramikschicht 34 abgewandten Oberfläche bzw. Stirnfläche der Isolationsschicht 41, 42 bildet jeweils eine Anlagefläche 44, 45 aus. Die eben ausgebildeten Anlageflächen 44, 45, welche darüber hinaus parallel zueinander angeordnet sind, sind insbesondere durch einen mechanischen Bearbeitungsprozess, wie Schleifen, oberflächenbearbeitet und mit einer relativ geringen Rauigkeit ausgestattet. Bevorzugt erfolgt die Ausbildung der Anlageflächen 44, 45 durch Doppelplanschleifen. Während die eine (untere) Anlagefläche 45 unmittelbar auf dem Grund 26 des Verformungsbereichs 27 des Injektorgehäuses 11 aufliegt, ist die andere (obere) Anlagefläche 44 in Wirkverbindung mit einem Gehäusedeckel 47 angeordnet. Der Gehäusedeckel 47 ist Bestandteil eines Gehäuses 50, das neben dem Gehäusedeckel 47 zumindest einen im Wesentlichen hülsenförmig ausgebildeten Gehäuserahmen 48 umfasst. Der insbesondere aus Metall bestehende Gehäuserahmen 48 ist auf nicht dargestellte Art und Weise, insbesondere durch eine Laserschweißnaht, mit dem Grund 26 des Injektorgehäuses 11 dicht verbunden. Der Gehäuserahmen 48, der das Sensorelement 32 an dessen Umfang vollständig umgibt, weist auf der dem Injektorgehäuse 11 bzw. dem Grund 26 abgewandten Seite einen flanschartig radial nach innen ragenden Halteabschnitt 51 auf, an dessen Unterseite der Gehäusedeckel 47 mit dessen Oberseite bündig anliegt. Durch eine entsprechende Dimensionierung der Höhe des Gehäusedeckels 47 sowie des Sensorelements 32 und des Gehäusedeckels 47 wird es ermöglicht, dass das Sensorelement 32 im Anbauzustand des Gehäuses 50 an dem Injektorgehäuse 11 mit einer Axialkraft F gegen den Grund 26 des Verformungsbereichs 27 kraftbeaufschlagt ist.The surface or end face of the
Die elektrische Kontaktierung der beiden Elektrodenschichten 35, 36 erfolgt über zwei metallische Kontaktelemente 52, 53, die insbesondere stiftförmig ausgebildet sind. Die beiden Kontaktelemente 52, 53 sind beispielsweise jeweils mit einer in der
Die Kontaktelemente 52, 53 sind, wie insbesondere anhand der
Wie darüber hinaus aus einer Zusammenschau der
Die in den
Die in den
Darüber hinaus kann es entsprechend der Darstellung der
Die Messeinrichtung 30c entsprechend der
Bei der in den
Die in der
Die in den
Die Funktionsweise der Sensorelemente 32, 32a bis 32f besteht darin, dass bei einer (elastischen) Deformation des Verformungsbereichs 27 infolge einer Druckänderung in der Versorgungsbohrung 19 durch das jeweilige Sensorelement 32, 32a bis 32f ein elektrisches Spannungssignal erzeugt wird, das über die Kontaktelemente 52, 53 an eine nicht dargestellte Auswerte- bzw. Messeinrichtung übermittelt wird. Aufgrund des Spannungssignals kann zumindest mittelbar auf eine Stellung der Düsennadel 16 in dem Injektorgehäuse 11 geschlossen werden, wobei dieses Signal der Ansteuerung der Düsennadel 16 dient.The mode of operation of the
Claims (12)
- Fuel injector (10), in particular common-rail injector, having an injector housing (11) in which there is formed a high-pressure chamber (15) which can be supplied with pressurized fuel via a supply bore (19) arranged in the injector housing (11), having a measuring device (30; 30a to 30d) for the at least indirect detection of the pressure in the high-pressure chamber (15) or in the supply bore (19), wherein the measuring device (30; 30a to 30f) is designed to detect an elastic deformation of a deformation region (27), which is arranged so as to be at least indirectly operatively connected to the supply bore (19) or to the high-pressure chamber (15), of the injector housing (11), wherein the measuring device (30; 30a to 30f) has a sensor element (32; 32a to 32f) which is arranged so as to be in abutting contact with the surface of the deformation region (27), wherein the sensor element (32; 32a to 32f) is electrically contacted by means of contact elements (52, 53), wherein the measuring device (30; 30a to 30f) is received in regions in a housing (50) which is connected to the injector housing (11), which housing surrounds the sensor element (32; 32a to 32f) at its circumference and covers said sensor element on the side situated opposite the deformation region (27), and wherein the housing (50), on the side situated opposite the deformation region (27), is arranged so as to be in abutting contact with the sensor element (32; 32a to 32f) and forces the sensor element (32; 32a to 32f) with an axial preload force (F) against the deformation region (27), wherein the housing (50) is composed of at least two elements, wherein one element is formed as a housing cover (47) which is preferably arranged so as to be in areal abutting contact with the sensor element (32; 32a to 32f) and which, on the side facing toward the sensor element (32; 32a to 32f), has a planar surface (61), and in that the contact elements (52, 53) which at least indirectly electrically contact the sensor element (32; 32a to 32f) are arranged in the housing cover (47), and the housing cover (47) interacts with a sleeve-shaped element (48) of the housing (50), which sleeve-shaped element has, on the side averted from the deformation region (27), a radially inwardly projecting holding section (51) against which the housing cover (47) bears axially on that side of the holding section (51) which faces toward the deformation region (27),
characterized
in that the sensor element (32; 32a to 32f) is formed as a piezo element (31) with a rectangular outline and with at least one piezoceramic layer (34) and at least two electrode layers (35, 36) and with insulation layers (41, 42), and in that two contact elements (52, 53) are provided which are arranged in the region of preferably diagonally opposite corner regions (57, 58) of the sensor element (32; 32a to 32f) in the housing cover (47) and which, on the side facing toward the sensor element (32; 32a to 32f), extend flush with the surface (61) of the housing cover (47). - Fuel injector according to Claim 1,
characterized
in that the housing cover (47) interacts with a sleeve-shaped element (48) of the housing (50), and in that the housing cover (47) is connected to the sleeve-shaped element (48) by means of a weld seam (96). - Fuel injector according to Claim 1,
characterized
in that the contact elements (52, 53) are connected, with the interposition of an electrically conductive adhesive (63) or a solder (64), to metallizations (39, 40), which in turn are connected in electrically conductive fashion to the electrode layers (35, 36). - Fuel injector according to Claim 3,
characterized
in that the contact elements (52, 53) are arranged so as to at least partially overlap the sensor element (32a), and in that the sensor element (32a) has, on the side facing toward the contact elements (52, 53) and at least in the region of overlap with the contact elements (52, 53), a recess (65) for the adhesive (63) or the solder (64) . - Fuel injector according to Claim 3,
characterized
in that the contact elements (52, 53) are arranged so as to entirely overlap the sensor element (32d), and in that the sensor element (32d) has, for each contact element (52, 53), in alignment with the contact element (52, 53), a recess (78, 79) which extends as far as the respective electrode layer (35, 36) and which is filled with solder (64) for the electrical connection between the electrode layer (52, 53) and the contact element (52, 53). - Fuel injector according to Claim 1,
characterized
in that the contact elements (52, 53) are connected at least indirectly to the electrode layer (35, 36) by means of in each case one intermediate element (66; 66f, 67; 67f, 75; 75e, 76; 76e). - Fuel injector according to Claim 6,
characterized
in that the intermediate element (66; 66f, 67; 67f) is formed as a spring element which is connected to the sensor element (32b; 32f) and which bears with a spring section (69) against the respective contact element (52, 53). - Fuel injector according to Claim 7,
characterized
in that the intermediate element (66f, 67f) bears under mechanical preload against a metallization (39, 40), which is connected to the electrode layer (35, 36), of the sensor element (32f). - Fuel injector according to Claim 7 or 8,
characterized
in that the intermediate element (66f, 67f) is received in positively locking and non-positively locking fashion in an in particular ring-shaped support element (90). - Fuel injector according to Claim 9,
characterized
in that the support element (90) is arranged between the contact elements (52, 53) and a bridging element (72f). - Fuel injector according to one of Claims 6 to 10,
characterized
in that the intermediate element (75; 75e, 76; 76e) is in the form of a connecting wire, in particular a bonding wire. - Fuel injector according to one of Claims 6 to 11,
characterized
in that the contact elements (52, 53) are arranged so as to not overlap the sensor element (32b; 32c) .
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102015220394.8A DE102015220394A1 (en) | 2015-10-20 | 2015-10-20 | fuel injector |
Publications (2)
Publication Number | Publication Date |
---|---|
EP3159533A1 EP3159533A1 (en) | 2017-04-26 |
EP3159533B1 true EP3159533B1 (en) | 2018-06-13 |
Family
ID=56896442
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP16188282.4A Active EP3159533B1 (en) | 2015-10-20 | 2016-09-12 | Fuel injector |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP3159533B1 (en) |
DE (1) | DE102015220394A1 (en) |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102014204629A1 (en) * | 2014-03-13 | 2015-09-17 | Robert Bosch Gmbh | Fuel injector, in particular common rail injector |
DE102014204746A1 (en) * | 2014-03-14 | 2015-09-17 | Robert Bosch Gmbh | Fuel injector, in particular common rail injector |
DE102015206029A1 (en) * | 2015-04-02 | 2016-10-06 | Robert Bosch Gmbh | fuel injector |
EP3088729B1 (en) * | 2015-04-30 | 2018-07-04 | Robert Bosch Gmbh | Fuel injector and device and method for assembly of a measuring device |
DE102015211186A1 (en) | 2015-04-30 | 2016-11-03 | Robert Bosch Gmbh | fuel injector |
-
2015
- 2015-10-20 DE DE102015220394.8A patent/DE102015220394A1/en not_active Withdrawn
-
2016
- 2016-09-12 EP EP16188282.4A patent/EP3159533B1/en active Active
Non-Patent Citations (1)
Title |
---|
None * |
Also Published As
Publication number | Publication date |
---|---|
EP3159533A1 (en) | 2017-04-26 |
DE102015220394A1 (en) | 2017-04-20 |
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