Patent ID: 7584829
Filing Date: 2009-09-08
Classification: F16F

Abstract:
1. A hydraulic vibration damper, comprising: a receiving pipe; a piston rod; a working piston being disposed on an end of the piston rod being received within the receiving pipe in a manner allowing oscillatory axial movement of the working piston within the receiving pipe, said working piston respectively dividing an inner chamber of the receiving pipe into a pulling chamber on a side occupied by the piston rod and a pushing chamber on another side remote from the piston rod, said working piston comprising through-flow channels effective for conducting a flow of damping fluid across said working piston when said working piston is moved in a pulling direction or a pushing direction; a damping valve including a first valve seat and a first valve washer cooperative with said first valve seat, said first valve washer being biased by a first damping resilient force in a direction of said first valve seat to cover at least a first one of said through-flow channels which is present in said valve seat, said damping valve opening when a first predetermined damping fluid pressure exceeds the first damping resilient force in a direction opposite thereto; and a pressure relief blow-off valve comprising a first annular washer having a surface facing the first valve washer, said first annular washer being biased in a closed position by a pressure relief resilient force greater than said first damping resilient force and which opens when a second predetermined damping fluid pressure exceeds said pressure relief resilient force, said surface of said first annular washer forming a variable first throttling site with the first valve washer, said first throttling site presenting a throttling cross-section which is variable depending on a range of piston speeds of the vibration damper in such manner that an increase in said throttling cross-section is attendant an initial increase in piston speed following said first damping resilient force being exceeded, and that a decrease in said throttling cross-section is attendant a further increase in piston speed beyond said initial increase, such that as said further increase in piston speed progresses, the damping fluid pressure continues to increase until said pressure relief blow-off valve opens when the damping fluid pressure exceeds the pressure relief resilient force thereby preventing the damping fluid pressure from significantly increasing beyond said second predetermined damping fluid pressure attendant an increase in the piston speed beyond a threshold piston speed present when said pressure relief resilient force is exceeded by the damping fluid pressure thereby protecting the vibration damper against cracking due to excessively high pressure levels which would otherwise develop.