Anti-theft screw part for attaching a wheel rim to a motor vehicle
An anti-theft screw part includes an annularly extending recess for engaging an adapter, which as viewed from the outward direction to the inward direction is limited by an outer edge, a bottom, and an inner edge. The screw part is assembled of a main piece and an insert piece. The main piece forms the outer edge, the inner edge is formed by the insert piece. The outer edge is limited by an outer wall surface, located on an outer circle, and by several internal projections, projecting from the outer circle towards the rotational axis up to a first circular line. The inner edge is limited by an inner wall surface, located on an inner circle and limited by several outer projections, projecting from the inner circle towards the exterior up to a second circular line. The first circular line is located completely within the second circular line. The diameter of the second circular line is larger than the diameter of the first circular line.
1. An anti-theft screw part comprising: a rotational axis and a recess formed at a free end region of the screw part and annularly extending, for engaging an adapter for rotating the screw part, which recess, as viewed from the outward to the inward direction, is limited by an outer edge, a bottom and an inner edge, wherein at least one of these edges form abutment faces for the adapter, the screw part is assembled of a main piece and an insert piece that are assembled and are firmly attached to each other, the main piece forming the outer edge and the inner edge being formed by the insert piece, the outer edge being limited by an outer wall surface located on an outer circle, wherein the outer edge is limited by a plurality of internal projections, which project from the outer circle towards the rotational axis to a first circular line, in that the inner edge is limited by an inner wall surface located on an inner circle and a plurality of outer projections, which project from the inner circle towards an exterior to a second circular line, in that the first circular line is located completely within the second circular line, in that the diameter of the second circular line is larger than the diameter of the first circular line, and in that the internal projections and the outer projections are formed as cylinder segments.
2. The anti-theft screw part according to claim 1 , wherein i) the cylinder segments of the internal projections extend across less than 180 degrees around the circumference of the outer circle, but more than 120 degrees around the circumference of the outer circle, and ii) the cylinder segments of the outer projections extend 150 to 210 degrees around the circumference of the outer circle.
3. The anti-theft screw part according to claim 1 , wherein all of the internal projections have the same shape or all of the outer projections have the same shape.
4. The anti-theft screw part according to claim 1 , wherein the number of the internal projections is equal to the number of the outer projections or the number of the outer projections differs from the number of the internal projections by a maximum of 2.
5. The anti-theft screw part according to claim 1 , wherein the number of the internal projections plus the number of the outer projections ranges from six to twelve.
6. The anti-theft screw part according to claim 1 , wherein the recess, as viewed in a plane transversally to the rotational axis, has at least one radial region in the form of a circular sector, wherein a first gap width in the plane is determined by the difference between the radii of the outer circle and the inner circle, and further includes a plurality of radial regions in the form of a circular sector, wherein a second gap width is determined by the difference between the radii of the outer circle and the second circular line, or by the difference between the radii of the first circular line and the outer circle.
7. The anti-theft screw part according to claim 6 , wherein a gap dimension of the recess, as viewed in a plane transversally to the rotational axis, at no location and with any measuring line orienteered in the plane, is smaller than the difference between the radii of the outer circle and the second circular line, or the difference between the radii of the first circular line and the outer circle.
8. The anti-theft screw part according to claim 1 , wherein the outer projections are arranged across unequal angles across the inner circle, or the internal projections are distributed across unequal angles across the outer circle.
9. The anti-theft screw part according to claim 1 , wherein the main piece either has a receiving bore wherein the insert piece has a head and a shaft, adapted to the receiving bore, or the main piece has an axial connector wherein the insert piece is annular and has an internal bore adapted to the connector.
10. The anti-theft screw part according to claim 1 , wherein the main piece or the insert piece is a one-piece part.
11. The anti-theft screw part according to claim 1 , wherein the diameter of the second circular line is at least 5% larger than the diameter of the first circular line.