An assembly for hoisting and lowering a drill string of a drilling rig includes a multiple displacement hydraulic cylinder having a blind end, a rod end, and a single piston rod configured for slidable extension and retraction movement within the interior space of the cylinder. The interior space is defined by three chambers, each chamber having a port allowing switchable flow of hydraulic fluid into and out from the cylinder. The assembly also includes a pumping and switching system with hydraulic fluid connections to each port of the cylinder. The pumping and switching system is configured to switch the direction of hydraulic fluid flow through each of the ports of the three chambers, thereby providing the assembly with a plurality of hydraulic fluid flow path combinations. Each flow path combination provides a different speed-to-force ratio for extending or retracting the piston rod, thereby hoisting or lowering the drill string.

A hydraulic actuator with no friction and zero leakage and its drive system are provided. The hydraulic actuator includes a thickened disc structure A and a thickened disc structure B. The second end face of the thickened disc structure A is connected with the first end face of the thickened disc structure B, and a control cavity is formed between the second end face of the thickened disc structure A and the first end face of the thickened disc structure B. The drive oil access hole is arranged on the thickened disc structure B, and the control cavity is connected with the drive oil access hole. The displacement output method based on elastic deformation is adopted, which completely avoids the nonlinear phenomena such as leakage and friction, and reduces the difficulty of high-precision control of the actuator.

The first piston of the first cylinder and the second piston of the second cylinder are connected so that the first piston and the second piston have the same displacement. The cross-section area of one side of the first piston is the smallest, and the cross-section area on the same side of the second piston is the third smallest. The two air chambers of the first cylinder and the two air chambers of the second cylinder are referred to as a first air chamber, a second air chamber, a third air chamber, and the fourth air in ascending order in the cross-section area. The control valve connects the air pressure source to the first air chamber, connects the second air chamber to the third air chamber, and opens the fourth air chamber to the atmosphere in the forward stroke.

The first piston of the first cylinder and the second piston of the second cylinder are connected so that the first piston and the second piston have the same displacement. The cross-section area of one side of the first piston is the smallest, and the cross-section area on the same side of the second piston is the third smallest. The two air chambers of the first cylinder and the two air chambers of the second cylinder are referred to as a first air chamber, a second air chamber, a third air chamber, and the fourth air in ascending order in the cross-section area. The control valve connects the air pressure source to the first air chamber, connects the second air chamber to the third air chamber, and opens the fourth air chamber to the atmosphere in the forward stroke.

A fluid pressure driving device includes a first air-fluid converter and a second air-fluid converter each configured to convert air pressure supplied from an air pressure source to fluid pressure, a fluid pressure actuator having a first pressure chamber and a second pressure chamber, an operation state acquisition unit configured to acquire an operation state of the fluid pressure actuator, and first and second air pressure valves respectively provided on first and second air supply paths, the first and second air supply paths being configured to supply air from the air pressure source to the first and second air-fluid converters respectively, wherein the control device is configured to control the first air pressure valve and the second air pressure valve on the basis of an acquired result from the operation state acquisition unit.

A hydraulic actuator with no friction and zero leakage and its drive system are provided. The hydraulic actuator includes a thickened disc structure A and a thickened disc structure B. The second end face of the thickened disc structure A is connected with the first end face of the thickened disc structure B, and a control cavity is formed between the second end face of the thickened disc structure A and the first end face of the thickened disc structure B. The drive oil access hole is arranged on the thickened disc structure B, and the control cavity is connected with the drive oil access hole. The displacement output method based on elastic deformation is adopted, which completely avoids the nonlinear phenomena such as leakage and friction, and reduces the difficulty of high-precision control of the actuator.

An actuator comprising: a piezo actuator; a drive having a drive chamber and a drive piston element driven by the piezo actuator; a first output having an output chamber and a piston element; and a second output having an output chamber and a piston element. At least part of the hydraulic fluid is conveyed out of the drive chamber by movement of the drive piston element and into the first output chamber. At least part of the hydraulic fluid is conveyed out of the drive chamber and into the second output chamber. The second output piston element has a hydraulically active second output face which is different in size from the first output face. There may be a coupling device mechanically coupling the first output piston element to the second output piston element.

An actuator comprising: a piezo actuator; a drive having a drive chamber and a drive piston element driven by the piezo actuator; a first output having an output chamber and a piston element; and a second output having an output chamber and a piston element. At least part of the hydraulic fluid is conveyed out of the drive chamber by movement of the drive piston element and into the first output chamber. At least part of the hydraulic fluid is conveyed out of the drive chamber and into the second output chamber. The second output piston element has a hydraulically active second output face which is different in size from the first output face. There may be a coupling device mechanically coupling the first output piston element to the second output piston element.

The present invention regards a fluid actuator arrangement comprising a first cylinder housing comprising a first piston body comprising a first through-bore and a first clamping element provided for releasable clamping onto a first piston rod. The first piston body comprises a second through-bore and a second clamping element provided for releasable clamping onto a second piston rod; a first static holding unit comprising a first clamping unit provided for releasable clamping onto the first piston rod; a second clamping unit provided for releasable clamping onto the second piston rod; a first base member coupled to the first piston rod via a first universal joint for providing a rotational motion of the first base member during longitudinal motion of the first piston rod. The present invention also regards a method for providing a rotational motion of a first base member.

A sanitary valve system (10) comprising an actuator arrangement (20) in an actuator housing (32) comprising a first piston chamber (30I) with a first piston (32I) separating the first piston chamber in a first upper cavity (341U) and a first lower cavity (341L) and having a first piston shaft (36I) configured to operate outside of the actuator housing. The valve system is configured to operate in multiple states. The operation of each state and transitions amongst states including identical states are controlled by regulating the liquid pressure or flow in each respective first and second upper and lower cavities. The regulation of liquid may be via a common distribution plate arrangement (90). The distribution arrangement may be with least one common distribution plate (92) with a set of canals (94) configured to connect at least one set of upper and lower regulation lines (82IU, 82IL,82IIU, 82IIL) with the respective first and second upper and communication lines (50IU, 50IL, 50IIU, 50I IL). A sanitary valve kit and a method of retrofitting an existing valve arrangement are also disclosed.