Pipe joints or couplings – Particular interface – Tapered
Patent
1984-12-14
1987-11-10
Smith, Gary L.
Pipe joints or couplings
Particular interface
Tapered
2853345, 285385, 2853824, 29512, 29525, 29DIG43, 123469, F16L 1904
Patent
active
047053062
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an injection line connection for internal combustion engines, as set forth in the classifying portion of claim 1, and a production process for a connecting fitting of a pressure connection thereof.
DISCUSSION OF THE PRIOR ART
As fuel is generally supplied to the individual operating cylinders of internal combustion engines under a considerable pressure, which in the case of diesel engines, may be several hundreds typically more than 500 of bars, considerable screwing forces have to be applied to the cap nuts of the pressure connections of the injection line connections which are involved therewith, so as to ensure a reliable seal between the external sealing taper of each connecting fitting and the internal taper portion of the associated connecting member. In that connection, it should be borne in mind that the injection lines which always have to have a plurality of curves in going from the injection pump to the associated injection nozzle on the operating cylinder of the internal combustion engine are only made of soft, non-alloyed, low-strength steel, and even local hardening of that material at the connecting fittings formed thereon cannot be permitted. If it were relatively hard, the material of the injection line, extending from the hardened connecting fitting, could not experience adequate resilient flexing in relation to the inevitable vibrations of the injection line when the internal combustion engine is running, so that those connecting locations could easily constitute the sources of vibration fractures. To achieve connections, which remain tight even during running conditions of the engine with strong pulsating pressure strains within the injection lines, it is necessary to apply so high sealing pressures at line connections that the material of the connecting fittings undergo first deformations. It has therefore been necessary to accept that the connecting fitting which is clamped between the cap nut and the connecting member of each pressure connection suffers from deformation when an injection line is repeatedly removed and fitted, with the result that such deformation prevents a satisfactory seal from being made and thus eventually renders the entire injection line useless. Another factor which has a detrimental effect is that, when the cap nuts are tightened, besides the axial compression loading, the material of the nipple is also subjected to a frictional loading which acts in its peripheral direction and which results in the fitting suffering from additional wear. Finally, when an injection line is fitted and removed on a number of occasions, its internal diameter becomes constricted at the ends thereof because of the radial forces generated by the hollow taper portion of the connecting member.
In accordance with the state of the art disclosed in British Pat. No. 888 055 (see also French Pat. No. 1 260 967) and also Product Specification sheet 73365, sheet 3 of January 1970, in order to avoid the last-mentioned wear phenomenon, a pressure ring which is of harder material than the injection line is provided within the cap nut, between the inner annular shoulder thereof and the rearwardly facing contact surface of the connecting fitting, in the hope that, when the cap nut is tightened, the pressure ring would remain bearing firmly against the connecting fitting and only the cap nut would be rotated relative to the pressure ring. If such rings also afford a good hard support for the cap nuts and make it possible for the comparatively large cap nuts which are conventionally employed nowadays on injection pumps and injection nozzles also to be used in conjunction with injection lines of small diameter, experience has shown however that, when tightening the cap nut, it is scarcely possible to prevent the ring, which generally bears against the inner annular shoulder of the cap nut over a larger area than at the rearward contact surface of the connecting fitting, from being rotated with the cap nut. When that happens, however, not only does
REFERENCES:
patent: 448717 (1891-03-01), Hogan
patent: 1925937 (1933-09-01), Schultis
patent: 2150524 (1939-03-01), Starr
patent: 2445702 (1948-07-01), Weyenberg et al.
patent: 3380764 (1968-04-01), Wilson
patent: 4133565 (1979-01-01), Shutt
German Patent Publication; Product Specification DIN 73365 of Jan. 3, 1970.
Binzer Norbert
Guido Jurgen
Guido Jurgen
Nicholson Eric K.
Smith Gary L.
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