In a diaphragm pump having a fluorine resin-made rolling diaphragm including: an inner circumferential portion that elongates along an outer circumferential surface of a piston; an outer circumferential portion that elongates along the inner circumferential surface of a cylinder; and a folded portion that is formed by folding back in a tubular space between the cylinder and the piston; and a pump chamber is separated by the rolling diaphragm in the cylinder, the rolling diaphragm is produced in an extended attitude corresponding to an attitude obtained when, by a projective movement of the piston, the outer circumferential portion is eliminated, and the folding of the folded portion is opened.

A diaphragm pump converts rotation of a motor into a reciprocating motion and drives a diaphragm. The diaphragm pump includes a partition configured to form a pump chamber together with a deformation portion of the diaphragm, a suction passage communicating with the pump chamber via a suction through hole extending through the partition, and a suction valve configured to open/close the suction passage. The valve body of the suction valve includes a leak structure configured to form a channel between the valve body and the seat surface of the partition.

A rolling diaphragm pump includes a housing, a rolling diaphragm, a piston, a motor, and a ball screw. Rotational motion of the motor is converted into linear motion by the ball screw to cause the piston to reciprocate, and a volume of a pump chamber is changed by deformation of the rolling diaphragm, thereby sucking and discharging a transport fluid. The ball screw includes a screw shaft placed coaxially with an axis and rotationally driven about the axis relative to the housing by the motor, and a nut portion screwed to the screw shaft so as to be reciprocatable in an axial direction and having an insertion hole formed over an entirety thereof in the axial direction at a position eccentric to the axis. A guide shaft configured to guide reciprocation in the axial direction of the nut portion is inserted through the insertion hole of the nut portion and fixed to the housing.

The exhaust passage structure comprises a differential pressure valve that closes an exhaust passage when a pressure in an upstream fluid chamber is higher than a pressure in a downstream fluid chamber and opens the exhaust passage when the pressure in the upstream fluid chamber is less than or equal to the pressure in the downstream fluid chamber. The exhaust passage includes an upstream portion opened to the downstream fluid chamber, and a downstream portion opened to the exterior of the pressure chamber. The upstream portion has a passage cross-sectional area larger than that of the downstream portion.

A mounting structure for a diaphragm and a retainer includes: the diaphragm that is formed to have a disc shape and includes a fixation part positioned in an outer circumferential part of the diaphragm, a movable part positioned in a central part of the diaphragm, and a linking part linking the fixation part and the movable part together, wherein a side of the diaphragm facing a pump chamber is defined as a front side and a side of the diaphragm opposite from the pump chamber is defined as a rear side; and the retainer that has an annular shape, supports the rear side of the movable part of the diaphragm, and reciprocates, together with the movable part, in an advancement/retreat direction to and from the pump chamber. The diaphragm has a first R-shaped part recessed toward the pump chamber, on the rear side of a boundary section between the movable part and the linking part. The retainer includes an abutment part that abuts against the rear side of the diaphragm and a second R-shaped part that is formed in an outer circumferential position of the abutment part so as to protrude toward the pump chamber and that mates with the first R-shaped part.

A composite diaphragm for a diaphragm pump or the like is formed of a flexible membrane with an outer edge, an inner part and a flexible membrane portion connecting the outer edge to the inner part. This flexible membrane is formed at least partially from an ultrahigh-molecular-weight polyethylene and another layer is formed from an elastomer selected from the group consisting of acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, ethylene-propylene-diene rubber, chloroprene rubber, styrene-butadiene rubber, fluororubber, silicone rubber and fluorosilicone rubber.

A diaphragm assembly includes a piston push block, a diaphragm, a middle piece, a balance wheel seat, and fasteners. The diaphragm includes a diaphragm body with protrusions which protrude toward the middle piece and extends into the balance wheel seat. The piston push block includes a piston head and a piston shaft. The piston head is located on the side of the diaphragm facing away from the middle piece, and the piston shaft extends towards the diaphragm and is embedded in the diaphragm protrusion. The middle piece includes a first through hole, the balance wheel seat includes a balance wheel, and the balance wheel includes an insertion hole for the corresponding diaphragm protrusion to be inserted in. The fastener fixes the piston push block, the diaphragm and the balance wheel seat from the side facing away from the working surface of the diaphragm.

A diaphragm assembly includes a piston push block, a diaphragm, a middle piece, a balance wheel seat, and fasteners. The diaphragm includes a diaphragm body with protrusions which protrude toward the middle piece and extends into the balance wheel seat. The piston push block includes a piston head and a piston shaft. The piston head is located on the side of the diaphragm facing away from the middle piece, and the piston shaft extends towards the diaphragm and is embedded in the diaphragm protrusion. The middle piece includes a first through hole, the balance wheel seat includes a balance wheel, and the balance wheel includes an insertion hole for the corresponding diaphragm protrusion to be inserted in. The fastener fixes the piston push block, the diaphragm and the balance wheel seat from the side facing away from the working surface of the diaphragm.