Venting unit, vulcanisation mould, and pneumatic vehicle tyre

A vulcanizing mold for a pneumatic vehicle tire having:

• at least one mold part with venting holes in which at least one venting units have been inserted;
• wherein the venting unit has a closed position and an open position and comprises the following component parts:
• a largely circular-cylindrical, sleeve-shaped housing, which can be pressed into the hole and has a largely constant inner diameter and a central axis,
• a valve insert, which has been inserted into the housing and is movable with respect thereto in the axial direction,
• a valve disk, which belongs to the valve insert, is circular in plan view and, in the closed position of the venting unit, sits with a peripheral edge region of a constant thickness flat against a seating surface which extends peripherally in the form of a ring around the outer end of the housing and is oriented at right angles to the central axis and such that it remains within the seating surface,
• a valve stem, which belongs to the valve insert, adjoins the valve disk and has an outer, cylindrical stem portion, an inner stem portion and a transitional portion between these stem portions,
• a helical compression spring, which surrounds the inner stem portion and the transitional portion of the valve stem and is supported by its one end on the housing and acts with its other end on the outer stem portion of the valve stem,
• wherein the outer edge region of the valve disk which in the closed position of the venting unit sits on the seating surface has a thickness of 0.10 mm to 0.40 mm, wherein the venting unit can be pressed into the hole that the seating surface extending peripherally around the outer end of the housing is inwardly offset with respect to the inner mold-part side by a distance of 0.05 mm to 0.35 mm and wherein the radially outer stem portion of the valve stem has an outer diameter which is 80% to 97% of the inner diameter of the housing.

A vehicle pneumatic tire comprising:

• a tire which has been vulcanized in a vulcanizing mold;
• the vulcanizing mold having at least one mold part having a venting unit:
• wherein the venting unit has a closed position and an open position and comprises the following component parts:
• a largely circular-cylindrical, sleeve-shaped housing, which can be pressed into the hole and has a largely constant inner diameter and a central axis,
• a valve insert, which has been inserted into the housing and is movable with respect thereto in the axial direction,
• a valve disk, which belongs to the valve insert, is circular in plan view and, in the closed position of the venting unit, sits with a peripheral edge region of a constant thickness flat against a seating surface which extends peripherally in the form of a ring around the outer end of the housing and is oriented at right angles to the central axis and such that it remains within the seating surface.
• a valve stem, which belongs to the valve insert, adjoins the valve disk and has an outer, cylindrical stem portion, an inner stem portion and a transitional portion between these stem portions,
• a helical compression spring, which surrounds the inner stem portion and the transitional portion of the valve stem and is supported by its one end on the housing and acts with its other end on the outer stem portion of the valve stem,
• wherein the outer edge region of the valve disk which in the closed position of the venting unit sits on the seating surface has a thickness of 0.10 mm to 0.40 mm, wherein the venting unit can be pressed into the hole that the seating surface extending peripherally around the outer end of the housing is inwardly offset with respect to the inner mold-part side by a distance of 0.05 mm to 0.35 mm and wherein the radially outer stem portion of the valve stem has an outer diameter which is 80% to 97% of the inner diameter of the housing.

A venting unit for a vulcanizing mold for a green tire, the venting unit comprising:

• a closed position and an open position;
• a largely circular-cylindrical, sleeve-shaped housing, which can be pressed into the hole and has a largely constant inner diameter and a central axis;
• a valve insert, which has been inserted into a housing and is movable with respect thereto in the axial direction;
• a valve disk that is circular in plan view and, in the closed position of the venting unit, sits with a peripheral edge region of a constant thickness flat against a seating surface which extends peripherally in the form of a ring around the outer end of the housing and is oriented at right angles to the central axis and such that it remains within the seating surface;
• a valve stem, which belongs to the valve insert, adjoins the valve disk and has an outer, cylindrical stem portion, an inner stem portion and a transitional portion between these stem portions;
• a helical compression spring, which surrounds the inner stem portion and the transitional portion of the valve stem and is supported by its one end on the housing and acts with its other end on the outer stem portion of the valve stem;
• wherein the outer edge region of the valve disk which in the closed position of the venting unit sits on the seating surface has a thickness of 0.10 mm to 0.40 mm;
• wherein the venting unit can be pressed into the hole that the seating surface extending peripherally around the outer end of the housing is inwardly offset with respect to the inner mold-part side by a distance of 0.05 mm to 0.35 mm;
• wherein the radially outer stem portion of the valve stem has an outer diameter which is 85% to 90% of the inner diameter of the housing;
• wherein the radially outer stem portion of the valve stem has a length of extent that the helical compression spring acts on this portion at a position which is located at a distance, taken from the outer end of the venting unit, of 30% to 60% of the overall length of the venting unit;
• wherein that the seating surface extending peripherally around the outer end of the housing is the outer free edge of the housing, so that, when a venting unit has been pressed into a hole, outside the seating surface there is a portion of the wall of the hole reaching up to the inner side of the mold part;
• wherein the outer edge region of the valve disk has a width of 0.20 mm to 0.30 mm and overlaps with the seating surface on the outer edge of the housing in such a way that, when the venting unit is closed, a gap with a width of 0.04 mm to 0.06 mm remains between the edge of the edge region of the valve disk and the portion of the wall of the hole;
• wherein the seating surface which extends peripherally around the end of the housing on the inner side of the mold part extends around the outside of an opening in the housing which outwardly widens in a funnel-shaped manner and is formed by a continuous decrease in the wall thickness of the housing, so that the supporting surface has a width of 0.20 mm to 0.35 mm;
• wherein the valve disk has a disk base part which reaches with a frustoconical portion of decreasing diameter up to the adjoining outer stem portion, wherein this frustoconical portion has parallel to the central axis a thickness of 0.25 mm to 0.40 mm and its smallest diameter is after the outer stem portion and is 0.20 mm to 0.40 mm greater than the diameter of the outer stem portion;
• and
• wherein on the outer stem portion of the valve stem there is formed at the transitional portion a supporting surface which extends peripherally in the form of a ring, on which the helical compression spring is supported.

A method of vulcanizing a tire with a mold, the method comprising:

• providing a green tire;
• providing a mold having a plurality of mold segments that form a segment ring;
• inserting a venting unit into a hole of a mold part of the plurality of mold segments, the venting unit having an open position and a closed position;
• wherein the venting unit has an outer edge region of a valve disk that sits on a seating surface that extends peripherally around an outer end of the housing when the venting unit is in the closed position;
• and
• initiating vulcanizing the green tire with the venting unit in the open position;
• transitioning the venting unit to the closed position when the green tire has been molded;
• and
• forming a pneumatic tire.