Friction damper

• US 4,765,444 A
• Filed: 05/16/1983
• Issued: 08/23/1988
• Est. Priority Date: 10/23/1979
• Status: Expired due to Fees

• Current Assignee: Fritz Bauer + Sohne Ohg
• Original Assignee: Fritz Bauer+Sohne Ohg
• Inventors: Bauer, Hans J., Bauer, Hans-Peter, Bauer, Fritz
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US06/494,680
• Time in Patent Office: 1,926 Days
• Field of Search: 188/381, 188/83, 188/129, 188/130, 188/134, 188/300, 188/271, 188/288, 188/322.11-322.22, 188/378-380, 188/268, 188/321.11, 188/264 R, 92/249, 92/251, 92/248, 92/258, 267/120, 267/64.11, 267/124, 267/129, 267/9 C, 267/9 B, 267/9 R, 267/9 A, 267/134-136, 267/140.1, 267/139-141.7, 74/531, 277/58, 277/59, 277/165, 277/178, 277/225, 277/169, 440/61, 248/636
• US Class Current: 188/129
• CPC Class Codes: D06F 37/20 Mountings, e.g. resilient mountings, for the rotary receptacle, motor, tub or casing; Preventing or damping vibrations
• CPC Class Codes: F16F 7/09 in dampers of the cylinder-and-piston type
• CPC Class Codes: F16H 2007/0891 Linear path
• CPC Class Codes: F16H 7/0831 of the dry friction type

Abstract

A frictional damper, includes a circular-cylindrical casing and a ram which is coaxially displaceable in the casing and the inner end of which is provided with a cylindrical friction piston. On its external face, the friction piston is provided with one or more friction elements which are elastically pressed against the inner wall of the casing. To obtain a uniform surface pressure over the entire friction surface of the friction element or elements during the entire life of the frictional damper, the friction piston is provided with a bushing having a circular-cylindrical external shape and of counter-holder flanges or disks which project radially from the bushing and delimit the latter at a fixed axial extent. Moreover, at least one annular-cylindrical friction sleeve which has a closed circumference, is made of an elastically yielding material and is under tension in its inner circumferential zone, is provided on the bushing. The damper is particularly useful for damping washing machines which have a spinning mode.

Claims

1. 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.

2. 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.

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

4. 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.

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

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

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

8. The improvement of claim 1 wherein

said at least one friction element comprises a pair of said friction elements.

9. 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.

10. The improvement of claim 9 wherein

the ends of said sleeve abut and are connected to each other by means of an adhesive layer.

11. 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.