Lead-lag damper device to limit an end-of-stroke force peak

A damper device for damping the relative movements of two elements of a mechanical system, which damper device comprises:

• a damping chamber filled with a hydraulic fluid and secured mechanically to one of the elements;
• a rod connected to the other of the elements and having a piston received and movable in the damping chamber in such manner as to define two hydraulic compartments;
• at least one calibrated orifice, provided in the piston for throttling the hydraulic fluid flowing from one hydraulic compartment to another hydraulic compartment while the piston is working in traction or in compression;
• and
• at least one compression hydraulic peak-limiting valve and at least one traction hydraulic peak-limiting valve, throttling the hydraulic fluid flowing from one hydraulic compartment to another hydraulic compartment, as from a determined amplitude of movement of the piston;
• wherein said damper device further comprises additional hydraulic means that are active in compression and in traction as soon as the piston reaches the end of its stroke, so as to constitute a progressive hydraulic abutment damping the end-of-stroke jolts of said piston, which additional hydraulic means comprise:
• in each end-of-stroke zone of the piston, a ring having calibrated radial orifices, said ring being mounted and centered on a cylindrical shoulder projecting into the corresponding hydraulic compartment in such manner as to define between said ring and said shoulder an annular fluid-flow space in fluid communication both with the corresponding hydraulic compartment and also with the corresponding hydraulic peak-limiting valve via the calibrated radial orifices;
• and
• a recessed end of the piston that comes to surround the ring and to close off progressively the calibrated radial orifices, during the end-of-stroke axial movement of said piston.