Actuator for an automated or automatic transmission, and method for controlling the actuator

An actuator (1) for an automated or automatic transmission, the actuator comprising:

• a cylinder housing (3), a piston unit (2), an end stop damping device, and a piston rod (13),
• wherein the piston unit (2) is coupled to the piston rod (13) and arranged in the cylinder housing (3) to be movable in two opposite directions along a longitudinal axis (4),
• wherein the piston unit (2) separates two pressure chambers (8, 9) of variable volume in the cylinder housing (3), the pressure chambers being configured to apply pressure to the piston unit (2) with compressed air from opposite sides,
• wherein the two pressure chambers (8, 9) are configured to be connected to a valve unit (14) configured to selectively switch between a pressurization or a purge of each of the two pressure chambers (8, 9), and
• wherein the end stop damping device is arranged in the actuator (1) for damping at least one end stop of the piston unit (2) and is composed of a first pneumatically active damping stage and a second mechanically active damping stage,
• wherein the first pneumatically active damping stage is configured to reduce the kinetic energy of the piston unit (2) in at least one movement direction thereof when the piston unit (2) approaches at least one of two opposite end stop faces (5, 6),
• wherein the first pneumatically active damping stage is formed on the cylinder housing (3) by a pneumatic damping element (19, 20), wherein the pneumatic damping element (19, 20) has an air outlet (34, 35) with a variable cross-sectional area for compressed air, which is configured to be pneumatically connected to a respective one of the two pressure chambers (8, 9) by switching the valve unit (14) into a purge position for the respective one of the two pressure chambers (8, 9), wherein the cross-sectional area (28, 29) of the air outlet (34, 35) is adjustable by a prevailing pressure in the respective pressure chamber (8, 9) connected thereto, and
• wherein the second mechanically active damping stage is configured to dissipate a kinetic energy of the piston unit (2) remaining after braking by the pneumatic damping element (19, 20), when the piston unit (2) reaches the at least one end stop face (5, 6),
• wherein the second mechanically active damping stage becomes active upon impact on at least one of the at least one end stop face (5, 6) and includes at least one mechanical damping element (40, 41) formed as a rubber buffer arranged on the piston unit at a piston end proximate to one of the at least one end stop face (5, 6) of the cylinder housing (3).