Fastening arrangement of an assembly part onto a carrier part

A fastening arrangement for securing an assembly part (40) on a carrier part (50), comprising:

• at least one fastening screw (10) including a screw head (11) with engaging surfaces for interacting with a tool, a screw shank (13), at least one radial projection (14) on the screw shank (13) at a spaced distance from the screw head (11) and a thread (15) located between the radial projection (14) and an end of the shank remote from the screw head (11),
• a sleeve (20) formed as a single unitary piece having an inner diameter along its entire length which corresponds at least to an outer diameter of the radial projection (14) and of the thread, said sleeve including a radially inward projection (22) formed with an inner diameter smaller than the diameter of the radial projection (14) but at least as large as the outer diameter of the screw shank (13) between the screw head (11) and the radial projection (14), an upper end of the sleeve comprises a head flange (23) and a lower end of the sleeve includes a foot flange (24) extending only outwardly, said fastening screw (10) is inserted into the sleeve such that the radially inward projection (22) is snapped over the radial projection (14) of the fastening screw (10) to locate the screw head (11) adjacent an outer side of the head flange (23),
• a flexible assembly ring (30) having an inner diameter smaller than an outer diameter of each of the head flange (23) and the foot flange (24), said assembly ring mounted on said sleeve between the head flange (23) and the foot flange (24) and the height of the sleeve between the head and foot flanges is at least double the height of the assembly ring and wherein an outer diameter of the assembly ring is less than the outer diameter of the head flange and an axial length of the assembly ring is greater than an axial thickness thereof,
• wherein said assembly part (40) includes a through-bore (41) and wherein the fastening screw (10), sleeve (20), assembly ring (30) and through-bore (41) are dimensioned such that the radial projection (14) and the foot flange (24) are adapted to not protrude from the through-bore (41).

A fastening arrangement for securing an assembly part (40) on a carrier part (50), comprising:

• at least one fastening screw (10) including a screw head (11) with engaging surfaces for interacting with a tool, a screw shank (13), at least one radial projection (14) on the screw shank (13) at a spaced distance from the screw head (11) and a thread (15) located between the radial projection (14) and an end of the shank remote from the screw head (11),
• a sleeve (20) formed as a single unitary piece having an inner diameter along its entire length which corresponds at least to an outer diameter of the radial projection (14) and of the thread, said sleeve including a radially inward projection (22) formed with an inner diameter smaller than the diameter of the radial projection (14) but at least as large as the outer diameter of the screw shank (13) between the screw head (11) and the radial projection (14), an upper end of the sleeve comprises a head flange (23) and a lower end of the sleeve includes a foot flange (24) extending only outwardly, said fastening screw (10) is inserted into the sleeve such that the radially inward projection (22) is snapped over the radial projection (14) of the fastening screw (10) to locate the screw head (11) adjacent an outer side of the head flange (23),
• a flexible assembly ring (30) having an inner diameter smaller than an outer diameter of each of the head flange (23) and the foot flange (24), said assembly ring mounted on said sleeve between the head flange (23) and the foot flange (24), wherein the assembly ring (30) at upper and lower ends thereof comprises radially inwardly projecting contact regions (39,39′) whose inner diameter corresponds roughly to the outer diameter of the sleeve (20) between the flanges (23,24), wherein the assembly ring is supported on the sleeve (20) between the head flange (23) and the foot flange (24) and between which the assembly ring can be radially compressed.

A pre-assembly comprising in combination:

• a carrier part;
• an assembly part including a through-bore therein;
• a fastening arrangement securing the assembly part to the carrier part, said fastening arrangement including:
• (i) at least one fastening screw (10) including a screw head (11) with engaging surfaces for interacting with a tool, a screw shank (13), at least one radial projection (14) on the screw shank (13) at a spaced distance form the screw head (11) and a thread (15) located between the radial projection (14) and an end of the shank remote from the screw head (11),
• (ii) a sleeve (20) having an inner diameter which corresponds at least to an outer diameter of the radial projection (14) and of the thread, said sleeve including a radially inward projection (22) formed with an inner diameter smaller than the diameter of the radial projection (14) but at least as large as the outer diameter of the screw shank (13) between the screw head (11) and the radial projection (14), an upper end of the sleeve comprises a head flange (23) and at a lower end of the sleeve includes a foot flange (24), said fastening screw (10) being inserted into the sleeve such that the radially inward projection (22) is snapped over the radial projection (14) of the fastening screw (10) to locate the screw head (11) adjacent an outer side of the head flange (23),
• (iii) a flexible assembly ring (30) having an inner diameter smaller than an outer diameter of each of the head flange (23) and the foot flange (24), said assembly ring being mounted on the sleeve (20) and arranged between the head flange (23) and the foot flange (24),
• (iv) said assembly part (40) including said through-bore (41) having an inner diameter at least as large as the outer diameter of the foot flange (24) and into which the sleeve (20) is inserted, wherein a lower side of the head flange (23) is supported on an upper edge region of the through-bore (41), wherein the inner diameter of the through-bore (41) is dimensioned such that the assembly ring (30) has portions radially pressed thereon in clamping engagement with the through-bore (41), said through-bore (41) further comprises an undercut (42) with an inner diameter enabling the assembly ring (30) under radial compression and subsequent expansion to be pushed through the undercut (42) and thereby the assembly ring is retained in the through-bore (41), and
• (v) said carrier part (50) includes a threaded bore (51) receiving the thread (15) of the fastening screw (10) and having an edge region to support the foot flange (24) of the sleeve (20).