A hydrostatic cylinder with a gas pressure accumulator, which is preferably designed as a piston accumulator, and which is arranged concentrically on the outer circumference of the cylinder is disclosed. A gas pressure is produced via a constant pressure source and is limited or is essentially constant in the gas pressure accumulator and also a constant pressure medium pressure is independent of the degree of filling of the gas pressure accumulator.

A cylinder includes a cylinder tube, a first closure part, a second closure part, and a piston unit. The cylinder tube has a first tube end and a second tube end. The tube and end closure parts define a cylinder interior. The piston unit defines at least one working space in the cylinder interior. The first closure part is connected to the tube by a first peripheral laser ring weld and the second closure part is connected to the tube by a second peripheral laser ring weld. The laser ring welds each define a fluid-tight sealing plane. A peripheral sealing ring is located between each closure part and a tube inner wall at an axial distance from the associated laser ring weld seam. The peripheral sealing ring defines a pressure-separated ring section between the peripheral sealing ring and the associated laser ring weld seam.

A working cylinder has a cylinder tube, a first closure part, a second closure part and a piston unit. The first closure part is arranged on a first cylinder tube end, the second closure part is arranged on a second cylinder tube end to define a cylinder interior. The piston unit defines at least one working chamber in the cylinder interior. The piston unit slides through the first closure part. The first closure part is joined to the cylinder tube by a first peripheral laser ring weld seam and the second closure part is joined to the cylinder tube by a second peripheral laser ring weld seam. The laser ring weld seams each define a fluid-tight sealing plane. A method for producing the working cylinder is provided.

A working cylinder has a cylinder tube, a first closure part, a second closure part and a piston unit. The first closure part is arranged at a first cylinder tube end and the second closure part is arranged at a second cylinder tube end, the cylinder tube and the first and second closure parts define a cylinder interior. The piston unit defines at least one working chamber in the cylinder interior. The piston unit slidably passes through the first closure part. The first closure part us joined to the cylinder tube in a positive-locking manner by a first circumferential laser ring weld seam. The second closure part is joined to the cylinder tube in a positive-locking manner by a second circumferential laser ring weld seam, and each of the laser ring weld seams define a fluid-tight sealing plane. At least one of the closure parts has an axially opening that is a circumferential concave receiving contour in which the cylinder tube engages. The receiving contour radially overlaps the cylinder tube, and a ring weld seam inclination angle thereof is 110 to 160 degrees.

A piston unit of a working cylinder includes a piston and a piston rod. The piston has an axial bore hole formed therein. The piston rod is received in the axial bore hole. The piston rod and the piston are connected by a material-bond by a circumferential laser ring weld seam. The laser ring weld seam defines a pressure medium-tight sealing plane.

A piston for a fluid-actuated working cylinder, with a piston base unit which is coaxial to a piston longitudinal axis, consisting of a rigid core body which has radial outer peripheral surface and of an annular filling body which is seated in an annular receiving groove. The receiving groove is coaxial to the piston longitudinal axis and in the region of the radial outer peripheral surface is designed with a radially outwardly facing groove opening in the core body. The piston further includes a ring element which consists of plastic. The ring element radially outwardly coaxially encompasses the piston base unit at least in the region of the filling body, being radially supported with a radial inner peripheral surface on the piston base unit, projecting radially beyond the radial outer peripheral surface of the core body and comprising an axially orientated axial support surface radially outside the piston base unit on its two axial face sides. The piston further includes an annular enveloping body which has rubber elastic characteristics.

This method of gas exchange for four-stroke piston internal combustion engine comprising gas exchange through an intake and an exhaust valves and includes gas exchange through a piston-controlled port in a cylinder sleeve: exhausting combustion products through the port at the end of the power stroke and at the beginning of the exhaust stroke, removal of exhaust gases from the port (from the space outside the port, outside the cylinder) and air supply to the port (supply into afore-mentioned space). As a result, the combustion products do not return to the cylinder through the port at the end of the intake stroke and at the beginning of the compression stroke. This effect is combined with air intaking into the cylinder through the port at the end of the intake stroke and at the beginning of the compression stroke.

A hydraulic actuator is disclosed that comprises a first, fixed portion and a second portion movable relative to the first portion. The second portion comprises a hydraulic actuating device for actuating a component, and the actuator further comprises an intermediate member configured to interconnect the first portion with the second portion and permit movement of the second portion relative to the first portion. The intermediate member is configured to convey hydraulic fluid to the hydraulic actuating device of the second portion through a body of the intermediate member.

A pneumatic actuator and control valve assembly has a housing with a control cavity for a control valve and an actuator cavity for an actuator piston and rod assembly. The control cavity and actuator cavity both have an elongated shape and are substantially parallel to each other. The control cavity has a supply port and first and second control valve outlet ports and at least one vent port with the control valve being movable through the control cavity for controlling communication between the supply port and the first and second outlet ports. The actuator cavity has first and second ports at the retracted and extended ends for shuttling the piston and within the actuator cavity between a retracted and extended end position. The housing has a first inlet and second inlet for passage of pressurized fluid to and from the housing,

A self-rotation graphene heat-dissipation device for a direct-drive electro-hydrostatic actuator, that includes inner and outer walls of a shell eccentrically arranged relative to each other, the shell sleeves on an outer side of a self-rotation mechanism. The self-rotation mechanism is arranged on an outer side of a shaft; the shaft is coaxial with the inner wall of the shell and connected with outer and inner end covers. The self-rotation mechanism includes a rotor and blades, the rotor sleeves on the shaft and is connected with the outer and inner end covers. The rotor is slidably connected with the blades, and outer walls of the blades are closely attached to the inner wall of the shell. Graphene heat-dissipation layers are coated on outer walls of all of the shell, blades, the rotor, the inner and outer end covers respectively.