Title of Invention

AN INJECTOR FOR A COMMON RAIL INJECTION SYSTEM OF AN INTERNAL COMBUSTION ENGINE

Abstract

The invention relates to an injector (2) for a common rail injection system of an internal combustion engine, said injector comprising an injector housing (4), a valve element (8) arranged in the injector housing (4), a sealing ring (22) used as a seal between a high-pressure region and a low-pressure region of the injector (2), and a bearing ring (24) used to support the sealing ring (22). Said bearing ring is arranged with the sealing ring (22) in an annular region (18) between the injector housing (4) and the valve element (8), and is provided with a plurality of relief grooves (36) arranged at a distance in the peripheral direction, in the lower side thereof opposing the sealing ring (22), and a plurality of recesses (34) arranged at a distance in the peripheral direction, in the outer peripheral edge (28) thereof. According to the invention, the relief grooves (36) and the recesses (34) are staggered in the peripheral direction.

Full Text

INJECTOR The invention is with regard to an injector for a common-rail injection system with features specified in the preamble of Claim 1. Prior Art Common-rail injection systems have a plurality of injectors that are supplied fuel, under control of an electronic motor control unit of a high-pressure pump, from a central high-pressure accumulator that is termed as common-rail and that inject the fuel into combustion chambers of the internal combustion engine. A common-rail injector is already established in DE 100 20 870 A1 of the applicant whose injector casing houses a valve part that is inserted into a stepped bore of the injector casing and is sealed with regard to the injector casing, using a soft sealing ring which serves as a washer between a high-pressure region and a low-pressure region of the injector. The sealing ring is inserted into an annulus collector above a ring shoulder of the stepped bore and supports itself against the ring shoulder. A metallic supporting ring is located between the sealing ring and the ring shoulder in order to prevent the sealing ring from being pressed and/or extruded by varying fuel pressures of up to 1900 bar prevailing in the high-pressure region above the sealing ring into a narrow annular gap located below the ring shoulder between the valve part and the injector casing. Since complete impermeability of the sealing ring cannot be guaranteed when pressures as mentioned above prevail, the supporting ring is provided with a total of four flat leakage or pressure-relieving grooves at its underside that faces the ring shoulder, these grooves providing a defined leakage between the supporting ring and the injector casing, in order to discharge the leakage flow passing by at the sealing ring and thus prevent build- up of a pressure cushion below the sealing ring that could result in unwanted axial displacement of the sealing ring. Since the supporting ring in injectors being currently serially manufactured by the applicant for common-rail injection systems, furthermore lies with its external peripheral rim in a sealing manner against the adjacent inner wall of the stepped bore, it, over and above this, has a recessed, sickle-shaped indentation in its external peripheral rim in an axial direction bordering every pressure-relieving groove. This indentation ought to enable passage of the leakage flow into the pressure-relieving grooves between the external peripheral rim of the supporting ring and the adjacent inner wall of the stepped bore. This type of design could, however, result in unwanted extrusion of the sealing ring's material through the recesses and the pressure-relieving grooves due to which the sealing function of the sealing ring can no longer be guaranteed and, consequently, could cause a breakdown of the entire injection system. Advantages of the Invention The injector in accordance with the invention with features mentioned in Claim 1 has the comparative advantage that the short path present through the recesses and the pressure-relieving grooves gets lengthened due to the offset between the recesses and the pressure-relieving grooves due to which the friction forces are increased considerably, which counters an extrusion of the sealing ring's material through the recesses and pressure-relieving grooves. In other words, the direct path present is blocked and a diversion is created, which in connection with the smaller passage cross-section in the region of the diversion i.e. between a recess and the adjacent pressure-relieving groove, counteracts extrusion of the sealing ring's material. Passage of the leakage flow can, thereby, continue to be guaranteed, whereby its flow speed is simultaneously advantageously reduced by the offset location of the pressure-relieving grooves and recesses in the peripheral direction. Apart from this, the injector in accordance with the invention has a supporting ring with a more robust construction since weak zones formed by the pressure-relieving grooves and recesses do not collapse and excessive movements in the region of the recesses are avoided, which is probably one of the causes for extrusion of the sealing ring's material. As a result of the location of the recesses and the pressure-relieving grooves, in accordance with the invention, the supporting ring exhibits a material thickness in the region of the recesses that, when compared to prior art, is larger at the groove depth of the pressure-relieving grooves. The lower edges of the recesses thereby come closer to the casing wall of the injector which, in turn, results in smaller gap cross-section in this region that counteracts extrusion. A preferred design of the invention provides for the pressure-relieving grooves and the recesses being offset in such a manner against one another that one recess is respectively located between two adjacent pressure-relieving grooves in the peripheral direction, while conversely one pressure-relieving groove is located between two adjacent recesses in the peripheral direction, preferably in the middle in both cases. Another preferred design of the invention provides for the supporting ring, as previously, having a total of four recesses in the peripheral direction, located at a distance of 90 degrees and four pressure-relieving grooves located in the peripheral direction, likewise at a distance of 90 degrees in order to provide for sufficient passage cross-section for the leakage flow, and provides that the pressure-relieving grooves are, however, located at an angular distance of 45 degrees from the recesses and vice versa in order to create the longest possible diversion between adjacent pressure-relieving grooves and recesses. - Pressure-relieving grooves in the preferred shape of curved seams embossed into the supporting ring appropriately exhibit a depth of 0.05 to 0.1 mm while the recesses appropriately exhibit a sickle-shaped cross-section and a depth of 0.12 mm to 0.17 mm and are cut out from the supporting ring. In accordance with another preferred design of the invention, the cross-sectional form of the ring shoulder of the stepped bore and the cross-sectional form of the supporting ring are, over and above this, aligned to one another in such a manner that the supporting ring between the recesses abuts with its external peripheral rim in an essentially sealing manner against a part of the inner wall of the stepped bore that lies above the ring shoulder and between the pressure-relieving grooves abuts with parts of its underside in a sealing manner against the ring shoulder of the stepped bore. These parts of the underside lying against the ring shoulder in a sealing manner advantageously border the valve part and do not stretch over the entire breadth of the supporting ring so that flow channels with a small flow cross-section, running outward from the sealing in a radial manner, abutting parts between the ring shoulder and the underside of the supporting ring in it's peripheral direction, remain free and create a connection between the recesses and the pressure-relieving grooves. The flow channels are, preferably, designed in the underside of the supporting ring but can, however, also be designed as an annular groove in the ring shoulder. The flow cross-section of these flow channels essentially correspond appropriately to those of the pressure-relieving grooves and the recesses. Drawings The invention is described below in greater detail in an exemplary embodiment by means of associated diagrams. provided in supporting ring 24 which only permit passage of smaller quantities of fuel in the sealing gap 20. These flow channels consist of four sickle-shaped recesses 34 in the external peripheral rim of the external supporting ring part 30 and four radial pressure-relieving grooves 36 in its underside, that are connected to one another by a fluid. The recesses 34 and the pressure-relieving grooves 36 are respectively located around the periphery of the supporting ring 24 at the same distance of 90 degrees but are, however, offset against one another in the peripheral direction at 45 degrees in order to prevent extrusion of the sealing ring material by the flow channels. The fluid connection between the recesses 34 and the respective adjacent pressure-relieving grooves 36 is created by the angled form of the supporting ring 24, best illustrated in Figure 5. The ring abuts the ring shoulder 14 only in the transition region between the supporting ring part 26 and the supporting ring part 30, while the two supporting ring parts 26 and 30 are aligned diagonally with reference to the ring shoulder 14, whereby the external supporting ring part 30 supports itself with its external peripheral rim 28 at the upper end of a transition radius 46 provided, for reasons of stability, between the upper part 12 of the stepped bore 6 and the ring shoulder 14. This forms a ring-shaped gap below the supporting ring 30 through which fuel from the recesses 34 can reach the pressure-relieving grooves 36. The axial recesses 34 have a sickle-shaped cross-section with a maximum depth T (Figure 4) of approximately 0.12 to 0.17 mm and are cut out from a radial supporting ring part 30 when the supporting ring 24 is manufactured. The radial pressure-relieving grooves 36 with a depth of 0.05 to 0.1 mm are formed by seams 40 that have a curved cross-section and that are embossed, from below in the radial supporting ring part 30 during manufacture of the supporting ring 24 and stretch across the entire breadth of the supporting ring part 30 (Figure 4). As is best illustrated in Figure 4, the supporting ring 24 lies respectively between the four recesses 34 with its external peripheral rim 28 against the inner wall of the expanded part 12 of the stepped bore 6 in a sealing manner while, between the four pressure-relieving grooves 36 represented by the shaded area respectively, the supporting ring bears, in a sealing manner, upon that part of the ring shoulder 14 that lies inward from the annular groove 38 in a radial direction with its inner, ring segment-shaped part 42 of its underside that is adjacent to the valve part 8. As is indicated by arrow A in Figure 4, fuel leakage flow that has passed the sealing ring 22, flows downwards up to the top side of the supporting ring 24, through recesses 34 between the supporting ring 24 and the inner wall of the expanded part 12 of the stepped bore 6 and flows from there in a peripheral direction through the flat annular groove 38 up to one of both adjacent pressure-relieving grooves 36 through which it then flows inwards in a radial direction in the gap 20 between the valve part 8 and the injector casing 4, from where it is discharged. The direct short path towards the inside, indicated by arrow B, is blocked so that, as a result of the diversion, extrusion of the sealing ring's material through the recesses 34 and the pressure-relieving grooves 36 is definitely avoided. Patent Claims 1. Injector for a common-rail injection system of an internal combustion engine with an injector casing, a valve part located in the injector casing, a sealing ring that serves as a washer between a high-pressure region and a low-pressure region of the injector as well as a supporting ring, serving as a support for the sealing ring, located together with the sealing ring in an annulus collector between the injector casing and the valve part, the supporting ring having several pressure-relieving grooves located at intervals in the peripheral direction at its underside that is turned away from the sealing ring and is provided with several recesses located at intervals in the peripheral direction in its external peripheral rim, characterised in that the pressure-relieving grooves (36) and the recesses (34) are located offset in the peripheral direction. 2. Injector according to Claim 1, characterised in that, one recess (34) respectively is located between two adjacent pressure-relieving grooves (36) in the peripheral direction. 3. Injector according to Claim 2, characterised in that the recess (34) is located in the middle between the adjacent pressure-relieving grooves (36). 4. Injector according to one of the preceding Claims, characterised in that one pressure-relieving groove (36) is located respectively between two adjacent recesses (34) in the peripheral direction. 5. Injector according to Claim 4, characterised in that the pressure- relieving groove (36) is located in the middle between adjacent recesses (34). 6. Injector.according to one of the preceding Claims, characterised in that the recesses (34) and the pressure-relieving grooves (36) are respectively located at the same angular distance from one another. 7. Injector according to one of the preceding Claims, characterised in that the supporting ring has four pressure-relieving grooves (36) and four recesses (34), whereby the recesses (34) are located at a distance of 45 degrees from the pressure-relieving grooves (36). 8. Injector according to one of the preceding Claims, characterised in that the supporting ring (24) comprises of an essentially axial supporting ring part (26) and an essentially radial supporting ring part (30) and is provided with pressure-relieving grooves (36) at its underside that faces away from the sealing ring (22) and with recesses (34) at its external peripheral rim (28). 9. Injector according to one of the preceding Claims, characterised in that the supporting ring (24) supports itself against a ring shoulder (14) of the injector casing (4), whose cross-sectional shape-is aligned in such a manner to the cross-sectional shape of the supporting ring (24) that the same lies above the ring shoulder (14) with its external peripheral rim (28) between the recesses (34) in an essentially sealing manner against the injector casing (4) and between pressure-relieving grooves (36) with parts (42) of its underside lying in a sealing manner against the ring shoulder (14), whereby the parts (42) of the valve part (8) that lie against each other in a sealing manner face each other and do not stretch across the entire breadth of the supporting ring (24). 10. Common-rail injection system, characterised by at least one injector (2) according to one of the preceding claims. Dated this 2 day of June 2006

Documents:

1953-chenp-2006 abstract duplicate.pdf

1953-chenp-2006 claims duplicate.pdf

1953-CHENP-2006 CORRESPONDENCE OTHERS.pdf

1953-CHENP-2006 CORRESPONDENCE PO.pdf

1953-chenp-2006 description(complete) duplicate.pdf

1953-chenp-2006 drawings duplicate.pdf

1953-chenp-2006-abstract.pdf

1953-chenp-2006-claims.pdf

1953-chenp-2006-correspondnece-others.pdf

1953-chenp-2006-description(complete).pdf

1953-chenp-2006-drawings.pdf

1953-chenp-2006-form 1.pdf

1953-chenp-2006-form 18.pdf

1953-chenp-2006-form 26.pdf

1953-chenp-2006-form 3.pdf

1953-chenp-2006-form 5.pdf

1953-chenp-2006-pct.pdf