Injection line connection

A pressure connection for connecting a free end of an injection line (1) having an axis to a connecting member (2) for use in internal combustion engines, said pressure connection comprising:

• a connecting fitting (3) formed from the material of said injection line (1) at said free end thereof;
• a pressure ring (6) made of a material which is harder than the material of said injection line, said pressure ring having an annular support projection (10) which, in cross-section, is rounded off at the edge adjoining said free end of said injection line, the outer peripheral surface (11) of said support projection having a taper angle .beta., said connecting fitting being rolled over said support projection outwardly from the axis of said injection line onto said outer peripheral surface, the inner surface of said free end of said injection line forming an external sealing taper (9) overlying said peripheral surface, said pressure ring (6) being fixedly connected by a press fit to said connecting fitting (3) and to the adjoining portion of said injection line (1), said pressure ring having a first annular shoulder axially spaced from and on the opposite side from said support projection and a shoulder extending radially beyond said support projection and said connecting fitting and forming annular abutment means (6a, 14) facing in the same direction as said free end of said injection line;
• a cap nut (4) adapted to threadedly engage said connecting member (2), said cap nut having an inner annular shoulder (5) and axially supporting said first annual shoulder of said pressure ring, said connecting member having an internal taper opening (7) having a taper angle .alpha. into which said connecting fitting is seated, said taper 60 angles .alpha. and .beta. being generally similar so that when said cap nut is tightened onto said connecting member, said pressure ring is forced axially into said connecting fitting and said connecting fitting is forced into said taper opening in said connecting member thereby forming a seal therebetween, said radially extending shoulder of said pressure ring extending beyond said connecting member taper opening;
• the wall thickness (s) of said injection line (1) being in the range of 1/5 to 1/3 the outside diameter (D) of said injection line;
• the outside diameter (d.sub.a) of said pressure ring being in the range of about 1.8 to 3 times said outside diameter (D);
• said support projection (10) measured from its origin at the main portion of said ring (6) at abutment means (6a, 14), having an axial length (L) of a dimension similar to wall thickness (s) and a radial wall thickness (w') that is at least 1/4 the outside diameter (D);
• and
• said free end of said injection line comprising said connecting fitting engages said annular abutment (6a, 14) means when said cap nut (4) is tightened down, thereby positively limiting torque on said cap nut.

An injection line connection for internal combustion engines with pressure connections at the ends of the injection line and, for each pressure connection, a connecting fitting which is formed from the material of the injection line and which can be sealingly and at the same time axially pressed by a cap nut, by way of a pressure ring which is of a material that is harder than the injection line and which is supported axially in one direction against an inner flat annular shoulder of the cap nut and axially in the other direction against a rearward contact surface of the connecting fitting and which at least bears inwardly against the injection line, against an internal taper portion of a connecting member which carries the cap nut on a corresponding male screwthread, with a sealing taper portion similar to the taper angle of the internal taper portion of about 60.degree., wherein the ring also extends over the connecting member beyond the taper opening thereof, characterised by the following features:

• (a) the injection line (1) has a wall thickness (s) in the range of from 1/5 to 1/3 of its outside diameter (D);
• (b) each ring (6) is provided at the side towards the connecting fitting with an annular support projection (10) which has an annular cross-section that is rounded off at the edge that is toward the connecting fitting and, along its outside periphery, a tapered outer peripheral surface (11) with a taper angle (.beta.) similar to taper angle (.alpha.) of the internal taper (7) of the associated connecting member (2) while the associated connecting fitting (3) comprises the free end of the associated injection line (1), which is flanged over outwardly around the supporting projection (10) on the peripheral surface (11) thereof and which with its outer periphery at the same time forms the sealing taper (9);
• (c) the largest diameter (d.sub.a) of each ring (6) is about 1.8 to three times the outside diameter (D) of the associated injection line (1);
• (d) each support projection (10), as measured from its origin at the main portion of said ring (6) at abutment means (6a, 14), is of an axial length (L) that is approximately equal to wall thickness (s) of the injection line (1) and a wall thickness (w') that is at least about 1/4 of the outside diameter (D) of the injection line (1);
• and
• (e) annular abutment means on said ring (6) which engages said flanged-over free end of said injection line when said cap nut is tightened down, thereby limiting torque on said cap nut, said annular abutment means comprising a hollow-conical abutment shoulder (14) which projects outwardly in the annular cross-section perpendicularly to the conical peripheral surface (11) from the point of origin of the outer peripheral surface (11) of its support projection (10).

A process for producing a connecting fitting for connecting the free end of an injection line to a threaded connecting member for use in internal combustion engines, the fitting comprising a pressure ring made of a material which is harder than the material of the injection line, said pressure ring having an annular support projection extending axially along the injection line adjacent the free end thereof, the support projection being rounded and having an outer peripheral surface having an angle .beta., said pressure ring having a first annular shoulder axially spaced from and on the opposite side form the support projection and a shoulder extending radially beyond the support projection and forming annular abutment means facing oppositely from said first annular shoulder, a threaded cap nut configured to engage the connecting member threads and having an inner shoulder to bear against said first annular shoulder of said pressure ring, the connecting member having an internal taper opening with a taper angle .alpha. generally similar to tape angle .beta., said process comprising the steps of:

• positioning the pressure ring around the injection line adjacent the free end thereof;
• placing the injection line and pressure ring in a pressing tool;
• flanging over the free end of the injection line around the rounded support projection of the pressure ring in a plurality of sequential steps with respective pressing punch members which are successively moved with a respective mandrel into the free end of the injection line, the pressure ring forming a lost die of the pressing tool, thereby forming a press fit between the pressure ring and both the injection line and connecting fitting;
• the pressure ring and flanged-over free end forming the connecting fitting and being tightly confined between the cap nut and the connecting member when they are threadedly engaged and tightened down, the free end of the injection line being thereby deformed so as to abut the abutment means and suddenly increase the resistance to further tightening of the cap nut on the connecting member.