Friction damper

Claim 2

In a frictional damper which includes a circular cylindrical casing with an inner wall and a ram which is coaxially displaceable in the casing and has one end which projects from the casing and another end which is provided with a substantially cylindrical friction piston, the friction piston being provided on one external face with friction means elastically pressed against the inner wall of the casing, the improvement wherein said friction piston is intergrally formed of plastic with said ram, and comprises a bushing having a substantially circular-cylindrical external shape and counter-holder flanges which project radially from said bushings and delimit the latter to a fixed axial extent, and wherein said friction means comprises at least one friction element constituting a substantially annular-cylindrical friction sleeve made of an elastically yielding closed cell polyurethane foam material, and held under substantial uniform radially directed tension against its inner circumferential zone by said bushing on which said sleeve lies, the inner diameter of said friction sleeve in the untensioned state being smaller than the external diameter of said bushing, said at least one friction sleeve being pretensioned on its inner circumference against said bushing by from about 5% to about 15%, wherein damping is achieved substantially solely by means of friction generated between the inner wall of said casing and said at least one friction sleeve.

Claim 3

An improved frictional damper according to claim 1, wherein said at least one friction sleeve has an external diameter (D') which is substantially equal to said internal diameter (D) of said casing.

Claim 4

An improved frictional damper according to claim 2, wherein said counter-holder flanges have diameters corresponding to said internal diameter (D) of said casing.

Claim 5

An improved frictional damper according to claim 2, wherein said damper further includes a third counter-holder flange formed on said bushing axially between two adjacent ones of said friction sleeves.

Claim 6

An improved frictional damper according to claims 1, wherein said counter-holder flanges have diameters corresponding to said internal diameter (D) of said casing.

Claim 7

An improved frictional damper according to claim 1, wherein said integral plastic friction piston and ram are injection-molded.

Claim 8

A frictional damper according to claim 1 wherein said annular-cylindrical friction sleeve has a closed circumference.

Claim 9

The improvement of claim 1 wherein said at least one friction element comprises a pair of said friction elements.

Claim 10

The improvement of claim 1 wherein said friction sleeve includes a separation lying along a line disposed substantially parallel to the longitudinal axis of said damper.

Claim 11

The improvement of claim 9 wherein the ends of said sleeve abut and are connected to each other by means of an adhesive layer.

Claim 12

In a frictional damper which includes a circular cylindrical casing with an inner wall and a ram which is coaxially displaceable in the casing and has one end which projects from the casing and another end which is provided with a substantially cylindrical friction piston, the friction piston being provided on one external face with friction means elastically pressed against the inner wall of the casing, the improvement wherein said friction piston is intergrally formed of plsatic with said ram, and comprises a bushing having a substantially circular-cylindrical external shape and counter-holder flanges which project radially from said bushing and delimit the latter to a fixed axial extent, and wherein said friction means comprises at least one friction element defining means for applying constant frictional force against said casing inner wall, and comprising a substantially annular-cylindrical friction sleeve made of an elastically yielding closed cell polyurethane foam material, and held under substantial uniform radially directed tension against its inner circumferential zone by said bushing on which said sleeve lies, the inner diameter of said friction sleeve in the untensioned state being smaller than the external diameter of said bushing, and flow-through orifice means communicating one side of said piston with the opposite side thereof, said at least one friction sleeve being pretensioned on its inner circumference against said bushing by from about 5% to about 15%, whereby when said ram moves within said casing said orifice means facilitates a free flow of fluid in the casing from one side of the friction piston to the other, and vice-versa, and damping is achieved substantially solely by means of friction generated between said casing wall and said friction generating means.

Claim 13

In a frictional damper which includes a circular cylindrical casing with an inner wall and a ram which is coaxially displaceable in the casing and has one end which projects from the casing and another end which is provided with a substantially cylindrical friction piston, the friction piston being provided on one external face with friction means elastically pressed against the inner wall of the casing, the improvement wherein said friction piston is intergrally formed of plsatic with said ram, and comprises a bushing having a substantially circular-cylindrical external shape and counter-holder flanges which project radially from said bushing and delimit the latter to a fixed axial extent, and wherein said friction means comprises at least one friction element defining means for applying constant frictional force against said casing inner wall, and comprising a substantially annular-cylindrical friction sleeve made of an elastically yielding closed cell polyurethane foam material, and held under substantial uniform radially directed tension against its inner circumferential zone by said bushing on which said sleeve lies, the inner diameter of said friction sleeve in the untensioned state being smaller than the external diameter of said bushing, and flow-through orifice means communicating one side of said piston with the opposite side thereof, said at least one friction sleeve being pretensioned on its inner circumference against said bushing by from about 5% to about 15%, whereby when said ram moves within said casing said orifice means facilitates a free flow of fluid in the casing from one side of the friction piston to the other, and vice-versa, and damping is achieved substantially solely by means of friction generated between said casing wall and said friction generating means.