Sealing device for a piston

Sealing device for a piston (1) provided for a piston (2) moving in a cylinder (8) of which one of the ends at least is closed by a fluid chamber (27), said piston (2) comprising at least one piston head (3) which includes at least one fixed skirt (5) and has, on the one hand, a piston support face (4) in order to exert a force on any mechanical, hydraulic or pneumatic transmission means (33) and, on the other hand, a compression face (11) which emerges in the fluid chamber (27) and which can receive the pressure of a fluid (36), characterized in that it comprises:

• at least one sliding skirt (6) of cylindrical shape housed in the cylinder (8) with a small clearance, placed in the extension of the piston head (3) on the side of the compression face (11) and in the axis of said head (3), said sliding skirt (6) being connected to said head (3) by a mechanical inter-skirt connection (7) which enables it to move in longitudinal translation with respect to said head (3);
• at least one pressure transmission channel (10) arranged inside the sliding skirt (6) and passing right through the latter in the axial direction;
• at least one extensible continuous segment (9) of continuous annular form, interposed between the fixed skirt (5) and the sliding skirt (6), and comprising an internal cylindrical segment face (12) subjected to the pressure of the fluid (36) via the pressure transmission channel (10), an external cylindrical segment face (13) capable of coming into contact with the cylinder (8), an axial segment face on the side of the fixed skirt (14) held directly or indirectly in sealed contact with the fixed skirt (5) and an axial segment face on the side of the sliding skirt (15) held directly or indirectly in sealed contact with the sliding skirt (6);
• at least one sliding skirt spring (16) which tends to bring the sliding skirt (6) closer to the fixed skirt (5), and to axially compress the extensible continuous segment (9).