A hydraulic booster using a variable-volume piston includes a main cylinder configured such that, if a fluid introduced into the upper portion of a main piston is pressurized by a pressurizing means, the fluid in the lower portion of the main piston is output. A guide moves downwards separately from the main piston and then moves to the original position by a return means. A variable-volume piston is integrally assembled on the guide such that the volume thereof increases during a downward movement and decreases during an upward movement, thereby changing the volume of the upper side of the main piston. A fluid storage-and-supply unit connects to fluid channels in the upper and lower portions of the main cylinder. This configuration boosts the pressure of the fluid discharged through the lower portion of the main cylinder due to a volume change caused by upward/downward movements of the variable-volume piston.

A device for riveting and a hydropneumatic device for pressure transmission, including a working piston and a transmitter piston in the form of a double-acting cylinder for transmitting pressure to the working piston, wherein a working stroke of the working piston in a working direction includes a first stroke and a subsequent second stroke, wherein the first stroke is controlled by means of pneumatic pressure acting on the working piston and the second stroke is controlled by means of pneumatic pressure acting on the transmitter piston, and wherein hydraulic fluid is displaced by the transmitter piston and the displaced hydraulic fluid effects the second stroke of the working piston. Regulation means having an actuating device are provided for regulating the pneumatic pressure on both sides of the double-acting cylinder of the transmitter piston such that the second stroke of the working piston is predefined by way of the regulation.

An actuator pressure intensifying assembly includes a mode valve and a gear motor assembly, the mode valve arranged to receive, at an input port, a supply pressure and to provide, at an output port, a control pressure to an actuator, the mode valve further configured to move, in response to the supply pressure exceeding a predetermined activation threshold, from a first mode in which the supply pressure flows directly from the input port to the output port in a first fluid flow path, and a second mode in which the supply pressure flows from the input port to the output port in a second fluid flow path which includes the gear motor assembly between the input port and the output port which intensifies the supply pressure such that the control pressure is higher than the supply pressure.

An actuator pressure intensifying assembly includes a mode valve and a gear motor assembly, the mode valve arranged to receive, at an input port, a supply pressure and to provide, at an output port, a control pressure to an actuator, the mode valve further configured to move, in response to the supply pressure exceeding a predetermined activation threshold, from a first mode in which the supply pressure flows directly from the input port to the output port in a first fluid flow path, and a second mode in which the supply pressure flows from the input port to the output port in a second fluid flow path which includes the gear motor assembly between the input port and the output port which intensifies the supply pressure such that the control pressure is higher than the supply pressure.

A hydraulic pressure amplifier arrangement (1) is described comprising a supply port (A1), a pressure outlet (A2) connected to the supply port via check valve means (3), an intensifier section (5) having a high pressure piston (6) in a high pressure cylinder (7), a low pressure piston (8) in a low pressure cylinder (9) and connected to the high pressure piston (6), and a control valve (12) controlling a pressure in the low pressure cylinder (9), wherein the control valve (12) comprises a hydraulically actuated valve element (13). Such a pressure amplifier arrangement should have a good operational behavior in a cost effective manner. To this end the control valve (12) comprises spring means 16 acting on the valve element (1) in a direction towards a starting position of the control valve.

A hydraulic intensifier and/or booster (HIB) for transforming an incoming hydraulic pressure at a relative low-pressure to an amplified outgoing hydraulic pressure at a relative high-pressure. The HIB comprising a hydraulic motor and an intensifying mechanism, possibly a hydraulic screw pump mechanism, wherein the hydraulic motor being arranged from the incoming hydraulic pressure to output power. The intensifying mechanism being arranged to receive the outputted power from the hydraulic motor and transform it to linear power of a piston and via the piston being arranged to build the amplified outgoing hydraulic pressure.

A hydraulic intensifier and/or booster (HIB) for transforming an incoming hydraulic pressure at a relative low-pressure to an amplified outgoing hydraulic pressure at a relative high-pressure. The HIB comprising a hydraulic motor and an intensifying mechanism, possibly a hydraulic screw pump mechanism, wherein the hydraulic motor being arranged from the incoming hydraulic pressure to output power. The intensifying mechanism being arranged to receive the outputted power from the hydraulic motor and transform it to linear power of a piston and via the piston being arranged to build the amplified outgoing hydraulic pressure.

A hydraulic actuator (1) is disclosed comprising a cylinder housing (2), a piston (5) with a piston rod (6) being displaceably arranged inside the cylinder housing (2) and a pressure amplifier (17) comprising an inlet section (18) with a pressure inlet port (20), an active section (19) with a high pressure outlet port (22), a low pressure chamber (32) and a high pressure chamber (38a). It is an objective of the invention to provide a hydraulic actuator (1) with a modular pressure amplifier (17). To this end, the hydraulic actuator (1) comprises a cartridge pressure amplifier (10) comprising a sleeve (10a) being arranged at least partially inside the piston rod (6), and wherein the pressure amplifier (17) is stationarily arranged inside the sleeve (10a).

A piezohydraulic actuator system includes four chambers: a first chamber defined by a drive bellows filled with a hydraulic fluid and movable by a piezo actuator, a second chamber defined by a hydraulic cylinder filled with the hydraulic fluid, which defines a first output; a third chamber defined by an output bellows filled with the hydraulic fluid, which defines a second output; and a fourth chamber defining a reservoir of the hydraulic fluid. The drive bellows is hydraulically connected via a first check valve to the second chamber. A hydraulic piston in the hydraulic cylinder is coupled mechanically to the output bellows. The drive bellows is hydraulically connected via a second check valve to the fourth chamber. The hydraulic fluid reservoir is hydraulically connected via a third check valve to the output bellows, and the hydraulic cylinder is hydraulically connected via a fourth check valve to the output bellows.

An inner cylinder inside an outer cylinder is disposed to be coaxial to an air pressure supply rod inside the inner cylinder. A first piston is disposed between the air pressure supply rod and the inner cylinder, a pneumatic chamber is disposed on a side of one surface (hydraulic surface) of the first piston in the inner cylinder, and a first hydraulic chamber is disposed on a side of the other surface. A second piston is disposed between the outer cylinder and the inner cylinder, and a second hydraulic chamber is disposed on a side of a surface of the second piston which is provided in the same direction as the hydraulic surface of the first piston in both of the cylinders. The inner cylinder is provided with a communication hole for transmitting a negative pressure along with movement of oil with which the first hydraulic chamber and the second hydraulic chamber are filled. In this configuration, it is possible to shorten an overall length of a fluid pressure cylinder.