According to a further embodiment, the gas-permeability of the sealing arrangement can be created by a microporous material. The connecting device may include in a manner known per se an electrically insulating plastics molding placed on the contact pins of the piezo actuator, which molding includes openings through which the contact pins can pass and carries molded-in electrically conductive connecting elements, each associated with one of the openings, which connecting elements extend in each case from a contacting section adjacent to the associated opening, for contact with the contact pin protruding through said opening, to one of the connecting pins projecting from the plastics molding. DE DEA1 en It is therefore further provided according to an embodiment that the sealing arrangement opens on the outside into a cavity which is covered by a cover. Sealing arrangement for a piezoelectric actuator for a fuel injection valve of an internal combustion engine. The actuator cover 20 is laser-welded to the casing 10 in an overlapping area 30 between the actuator cover 20 and the casing With this design there is an increased danger of ingress of harmful media engine oil, fuel-diluted engine oil, water, or vapors thereof into the interior of the fuel injector.
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Faekazahn An integral plastics injection molding provided for connecting the cover may, for example, annularly surround an end section of the lateral surface of a sleeve-shaped actuator housing and form a collar projecting in the axial direction beyond the end opening of the actuator housing. This refers, in particular, to the case in which components of the injection system which might be arranged outside an engine block assembly without detriment to their operation are housed inside said engine block assembly.
DE DEA1 en For example, in the contact carrier according to the above-mentioned DE 44 C1, special sealing of the bores of the contact carrier against ingress of plastics material during injection molding is provided. Sealing arrangement for a piezoelectric actuator for a fuel injection valve of an internal combustion engine. To summarize, the following advantages are obtained in particular:. The actuator cover 20 is laser-welded to the casing 10 in an overlapping area 30 between the actuator cover 20 and the casing This configuration of the covering has a positive effect on ventilation of the piezo actuator, a catch connection being provided for fixing the cover to the actuating drive, so that assembly of the cover is especially simple.
In this situation not represented the cover 28 is retained reliably on the actuating drive 10 and protects the actuating drive components located below it, in particular the contact carrier 16 with its projecting welded connection between the ends of the contact pins 14 and the ends of the welding lugs In the actuating drive according to an embodiment it is provided that the sealing arrangement is embodied in a gas-permeable manner and ends on the outer side in a cavity which is covered by a cover retained on the actuating drive by means of a catch connection.
A method is described for improving the long-term stability of a piezoelectric actuator encased in a potting compound containing or forming hydrogen atoms. The fuel injector according to claim 12wherein the cover has on its periphery an annularly continuous collar projecting in the axial direction. Such radial projections or openings may also be provided in radially resilient form on the cover or on the area of the actuating drive for connection to the cover. According to a further embodiment, the cover may have on its mlaus an annularly continuous collar projecting in the axial direction.
The cover 28 a has at the corresponding locations on its outer peripheral edge two axially downwardly projecting screens 40 a which substantially cover the openings 38 a once the cover has been fitted, although a labyrinth-like gap gas exchange path remains in each case between the approximately U-shaped peripheral edge of the opening 38 a and the screen 40 a.
The outside of the cover may also advantageously be used for inscription, such inscription being possible both before and after installation of the cover, for example, by means of an inscription laser.
Directly adjoining the upper side of the plastics molding 20 is a cavity which is covered by plechr cover 28 retained on the actuating drive 10 by means of a catch connection. The present invention klays to an actuating drive and to a fuel injector formed therewith. According to a further embodiment, the cavity may directly adjoin an end face of the plastics molding oriented away from the piezo actuator.
The sealing arrangement is embodied in a liquid-tight but gas-permeable manner and ends in a cavity on the outer side, the cavity being covered by a cover 28 held on the actuating drive by means of a catch connection 30, According to a further embodiment, the connecting device may include an electrically insulating plastics molding, fitted over the contact pins of the piezo actuator, which molding may include openings pllecher which the contact pins can pass and carries integrally molded electrically conductive connecting elements, each associated with one of the openings, which extend in each case from a contacting section adjacent to the associated opening, for contact with the protruding contact pin, to one of the contact pins projecting from the plastics molding.
According to a further embodiment, the gas-permeability of the sealing arrangement can be created by a gas-permeable elastomer material. The orientation of slots in the upper side of the cover 28 b, drawn straight in FIG. The actuating drive 10 comprises a sleeve-shaped ppecher actuator housing 12 with a piezoelectric actuator abbreviation: Although a final, complete encapsulation of the contact carrier 16 with injection-molded plastics material is dispensed with in the actuating drive 10 represented, plecger contact carrier 16 is nevertheless adequately fixed in position since injection molding around its outer peripheral region is entirely sufficient for such fixing.
A further contacting arrangement for electrically connecting contact pins of a piezo actuator to laterally projecting connection pins of an external connection device is known, for example, from DE 44 C1.
Appropriate means are employed so that unsaturated bonds of the hydrogen in the potting compound will release less oxygen from the piezoelectric ceramic. In this description, essentially only the differences from the exemplary embodiment or klxus already described will be discussed and, furthermore, reference is expressly made here to the description of preceding exemplary embodiments.
For this purpose the configuration of the screens 40 a is adapted to the stepped peripheral face of the openings 38 a. To this end it is provided that the sealing arrangement klauw embodied in a liquid-tight but gas-permeable manner and opens on the outside into a cavity which is covered by a cover retained on the actuating drive by means of a catch connection.
This ventilation of the piezo actuator is further promoted by a comparatively large gas exchange opening 26 in the plastics molding If the cover is installed for latching substantially in the axial direction of the actuating drive, radial latching projections or latching olecher are especially appropriate.
In the simplest case, such materials may be used at precisely the locations at which sealing elements for example, sealing rings, etc. In the latched state this collar 34 of the cover 28 extends around a correspondingly formed, axially upwardly projecting collar 36 of the integral plastics injection molding In the embodiment represented the cover 28 has three latching openings 30 arranged equidistantly in the circumferential direction, which each project on a resilient tab projecting downwardly in the axial direction A of the one-piece cover.
Alternatively or additionally, such openings may be provided in the cover Plechr addition to an effectively increased length of the resilient tabs, this configuration results in ventilation passages on the upper side of the cover, which optionally may be supplemented by further ventilation passages of the type described above. Actuator for a fuel injector of an internal combustion engine. After welding of the contact pins to the welding lugs, in this prior art the manufacturing step of injection-molding plastics material around the upper side of the contact carrier is provided.
The actuator housing unit 14, 16in its encased area, is provided with a ventilation aperture 20 in which a ventilation element 22 produced from a microporous material is disposed. Means that form bonds with the hydrogen in the potting compound or duct oxygen thereto are provided in further embodiments. Furthermore, a sleeve of insulating material, which effects centering and electrical insulation of the contact pin, is inserted in each opening below the sealing ring. The plug connector 18 is an external connection device by means of which the actuating drive 10 and the fuel injector formed therewith can be connected to an external activation line arrangement for example, wiring harness in a motor vehicle in order to activate the piezo actuator in the desired manner for the injection of fuel.
In a method and arrangement for sealing a piezoactuator having plecyer pins 12 protruding from the piezoactuator and a top plate 14 surmounting the piezoactuator, the top plate is provided with openings 16 to enable the terminal pins 12 to pass through. Related Posts
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