Piston hydraulique a valve porte-joint de refroidissement et de lubrification

A hydraulic piston (1) consisting of a cylindrical body (6) housed in a small clearance in a cylinder (4), said piston (1) being translatable in said cylinder (4) with which it forms a hydraulic chamber (5) of a variable volume, a first end of said piston (1) having a compression face (10) opening into the hydraulic chamber (5) for receiving the pressure of a fluid (11), while the other end of said piston (3) has a piston support surface (8) for exerting a force on the transmission means (9), said piston (1) being characterized in that it comprises:

• At least one cooling and lubricating gasket valve (2) positioned on the side of the compression surface (10) and in the extension of the cylindrical body (6) with respect to which it can move in longitudinal translation over a short stroke, said valve (2) comprising, first, a piston-side axial valve surface (23) which has a circular flow closure contact surface (24) which can come into contact with a valve contact surface (26) on the compression surface (10), said valve (2) having secondly an external cylindrical valve surface (14) which exposes the sealing means (16) which can come into contact with the cylinder (4) and remain sealed, said valve (2) comprising, third, a chamber-side axial valve surface (15) which faces the hydraulic chamber (5);
• at least one intermediate fluid outlet chamber (29) formed within the circular flow closure surface (24) by the axial piston-side valve surface (23) and the compression surface (10);
• at least one flow calibration opening (27) which passes through the cooling and lubricating gasket valve (2) mainly through the axial direction, the hydraulic chamber (5) communicating with the intermediate fluid outlet chamber (29) via said opening (27);
• at least one valve stop-link (3) which connects the cooling and lubricating gasket valve (2) to the cylindrical body (6), said stop-link (3) allowing said valve (2) to approach said body (6) to the point that the circular flow closure seal surface (24) contacts the valve contact surface (26), while said stop-link (3) prohibits said valve (2) from moving away from said body (6) more than a certain distance;
• At least one valve return spring (30) which tends to move the cooling and lubricating gasket valve (2) away from the cylindrical body (6).