An actuator assembly which has a primary force module having a compression spring can be is compressed by a first fluid pressure-operated piston reciprocally mounted in the primary force module. There is a tandem piston module connected to the primary force module which has a second fluid-activated piston. When the spring of the primary force module is compressed, indicating that an attached valve is in the open position, the tandem module is actuated to apply a counter balancing force against the primary piston which allows the spring to expand and move the primary piston to a position which is sufficient to permit movement of the valve element of the actuated valve to indicate the valve is not stuck in an open position.

A compressed air provision device (2) for aerating a first pressure chamber (10) of a pneumatic actuator in order to actuate an actuator element (11) of the pneumatic actuator (3) in accordance with an actuation specification, in particular a position, movement, pressure and/or force specification. The compressed air provision device (2) is configured to calculate an aeration period (bd) and to aerate the first pressure chamber (10) in accordance with the calculated aeration period (bd) in order to bring about actuation of the actuator element (11) in accordance with the actuation specification.

A compressed air provision device (2) for aerating a first pressure chamber (10) of a pneumatic actuator in order to actuate an actuator element (11) of the pneumatic actuator (3) in accordance with an actuation specification, in particular a position, movement, pressure and/or force specification. The compressed air provision device (2) is configured to calculate an aeration period (bd) and to aerate the first pressure chamber (10) in accordance with the calculated aeration period (bd) in order to bring about actuation of the actuator element (11) in accordance with the actuation specification.

A fluid pressure cylinder includes a first cylinder portion and a second cylinder portion disposed in parallel, and a supply-and-discharge port. The first cylinder portion is partitioned by a first piston into a head-side first accumulation chamber and a rod-side second accumulation chamber. The second cylinder portion is partitioned by a second piston into a head-side release chamber and a rod-side drive chamber. Pressurized fluid is supplied to and discharged from the second accumulation chamber and the drive chamber through the supply-and-discharge port. An end of a first piston rod connected to the first piston and an end of a second piston rod connected to the second piston are connected to each other. The first piston includes a communication switching valve switching communication between the first accumulation chamber and the second accumulation chamber, between enabled and disabled.

A modular fluid actuator system is provided for generating a relative motion between a first fluid transfer chamber of a first module unit and a piston rod arrangement in an axial direction. The modular fluid actuator system comprises a fluid supply, a valve device coupled to the fluid supply and to the first fluid transfer chamber, a control unit coupled to the valve device for controlling the relative motion between the first fluid transfer chamber and the piston rod arrangement, the first fluid transfer chamber is coupled to a first sleeve portion exhibiting a first expandable hollow space arranged for fluid communication with the valve device via the first fluid transfer chamber.

A modular fluid actuator system is provided for generating a relative motion between a first fluid transfer chamber of a first module unit and a piston rod arrangement in an axial direction. The modular fluid actuator system comprises a fluid supply, a valve device coupled to the fluid supply and to the first fluid transfer chamber, a control unit coupled to the valve device for controlling the relative motion between the first fluid transfer chamber and the piston rod arrangement, the first fluid transfer chamber is coupled to a first sleeve portion exhibiting a first expandable hollow space arranged for fluid communication with the valve device via the first fluid transfer chamber.

A cylinder actuator includes a body assembly and a piston assembly. The body assembly includes a first cylinder nested concentrically within a second cylinder. The piston assembly slides linearly within the first and second cylinders. The piston assembly includes a first piston assembly end and a second piston assembly end. The first piston assembly end includes first and second pistons. The first piston moves within the first cylinder. The second piston moves within the second cylinder. The piston assembly includes first and second piston rods. The first piston rod extends from the first piston through a first end of the first cylinder. The second piston rod extends from the second piston through a first end of the second cylinder. The piston rods are joined at the second end of the piston rod assembly located outside of the first and second cylinders.

A linear drive system, in particular for a closure unit of a blow mold installation, with a simpler and more compact structure, a higher retraction and expansion speed in rapid mode, higher forces in power mode, and reduced energy consumption, than the prior art includes a cylinder arrangement which brings about a retraction and extension movement in rapid mode by separate hydraulically active faces which are independent of a larger hydraulically active face which is acted on with pressurized hydraulic fluid only in power mode. During the extension movement in power mode, however, the hydraulically active faces cooperate which contributes to high forces with a compact structure of the drive system.

A cylinder device includes: a first piston (8) inserted in a first cylinder hole (4) so as to be movable in an axial direction, a piston rod (7) being hermetically inserted in the first piston (8), the first piston (8) being fixed to the piston rod (7); a second piston (10, 37) inserted in a second cylinder hole (5) so as to be movable in the axial direction, the piston rod (7) being inserted in the second piston (10, 37); and a partition wall (13) dividing a cylinder hole (6) into the first cylinder hole (4) and the second cylinder hole (5), the partition wall (13) being movable in the axial direction.

The invention concerns a method for estimating an external force acting on an electrohydrostatic actuator, the actuator comprising a ram including a first chamber, a second chamber and a piston located between the first chamber and the second chamber, a pump capable of injecting fluid into the chambers for controlling a movement of the piston, and an electric motor driving the pump, the method comprising steps of: estimating, by means of at least one state observer (21, 22), a dynamic component and a static component of a difference in equivalent fluid pressure between the first chamber and the second chamber from a rotational speed of the electric motor, a position of the piston and a supply current of the electric motor, estimating the external force by means of a post-processing module (23) as a combination of the estimated dynamic component and static component of the difference in fluid pressure.