An accumulator includes a pressure vessel including a first section and a second section joined to each other via a joint portion and a partition portion separating an interior space of the pressure vessel into a liquid chamber and a gas chamber so that a volume ratio between the liquid chamber and the gas chamber in the pressure vessel is variable. The first section includes a thread portion for fastening the accumulator to a support member. The second section includes an abutting portion disposed opposite to the thread portion across the joint portion in an axial direction of the thread portion and configured to abut on the support member when the accumulator is fastened to the support member.

A fluid tank includes polymeric liner comprising an upper wall and a lower wall. The upper wall and the lower wall define a cavity therebetween. A weld joint joins the upper and lower walls together. A method for assembling a fluid tank includes overlapping surfaces of an upper wall and a lower wall to form a liner defining a cavity. The method includes joining the surface of the upper wall and the surface of the lower wall together by welding to form a weld joint between the upper wall and the lower wall. The method can include cooling the weld joint to control warpage of the liner at the weld joint.

An accumulator includes a pressure vessel and a partition portion separating an interior space of the pressure vessel into a liquid chamber and a gas chamber so that a volume ratio between the liquid chamber and the gas chamber in the pressure vessel is variable. The pressure vessel includes a first section including a thread portion for fastening the accumulator to a support member and a second section joined to the first section and formed by a single piece including a tool engagement portion capable of engaging with a tool for rotating the accumulator. The first section and the second section are fitted together by mating portions coaxial with the thread portion and the tool engagement portion.

A diaphragm accumulator provided with a flexible diaphragm inside an accumulator housing has a stress relaxing member having a contact surface which the diaphragm deformed by a pressure fluctuation inside the accumulator housing contacts and regulating the deformed attitude of the diaphragm by the contact surface on the inner surface. When the diaphragm is deformed by the pressure fluctuation inside the accumulator housing, the stress relaxing member regulates the deformed attitude of the diaphragm to reduce a stress generated in the diaphragm.

A method for producing pressure vessels, including pressure accumulators, such as hydraulic accumulators and parts of the parts of the accumulator (24). The parts produced by a 3D printing method can include one or more or all of two housing parts and a separating element separating the interior chamber of the two hosing parts are at least partially produced by a 3D printing method.

An accumulator is provided with a communication passage which allows communication between a space inside a gas filling opening and a gas filled chamber in a state where a diaphragm contacts an opening peripheral edge of the gas filling opening and which is formed by, for example, uneven shapes provided in either or both of the diaphragm or/and the opening peripheral edge of the gas filling opening.

A diaphragm accumulator provided with a flexible diaphragm inside an accumulator housing has a stress relaxing member having a contact surface which the diaphragm deformed by a pressure fluctuation inside the accumulator housing contacts and regulating the deformed attitude of the diaphragm by the contact surface on the inner surface. When the diaphragm is deformed by the pressure fluctuation inside the accumulator housing, the stress relaxing member regulates the deformed attitude of the diaphragm to reduce a stress generated in the diaphragm.

A shell member 10 constituting an accumulator 100 including a cover member 30, a shell member 10 having a cylindrical portion 11, an opening portion 13 formed at one end of the cylindrical portion 11 and welded to the cover member 30, and a closed portion 12 formed at another end of the cylindrical portion 11, and an accumulation part 70 accommodated in the shell member 10. The cylindrical portion 11 includes an upper end portion 11a, and a protruding portion 11c having the opening portion 13. The protruding portion 11c is thicker than the upper end portion 11a.

An accumulator according to an embodiment includes, for example, a base member; a cover member welded to the base member, the cover member and the base member defining a pressure chamber therebetween; a stretchable partition member that partitions the pressure chamber into an inner chamber and an outer chamber; and a labyrinth structure provided in at least one of a first part of the base member and a second part of the cover member. The first part is located closer to the outer chamber than a welded part between the base member and the cover member. The second part is located closer to the outer chamber than the welded part, facing the first part.

A fluid tank includes polymeric liner comprising an upper wall and a lower wall. The upper wall and the lower wall define a cavity therebetween. A weld joint joins the upper and lower walls together. A method for assembling a fluid tank includes overlapping surfaces of an upper wall and a lower wall to form a liner defining a cavity. The method includes joining the surface of the upper wall and the surface of the lower wall together by welding to form a weld joint between the upper wall and the lower wall. The method can include cooling the weld joint to control warpage of the liner at the weld joint.