Anti-drainback valves, flex tube assemblies that include one or more anti-drainback valves, and fluid filters that include one or more flex tube assemblies and/or anti-drainback valves are disclosed. In embodiments the anti-drainback valves and flex tube assemblies are described in the context of their use in a multi (e.g. dual) pump fluid filter, such as a dual pump transmission fluid filter. Dual pump fluid filters including integral and separable flex tube assemblies are also described.

A filter device allows avoiding liquid and dust before filtration to flow out to a tank during replacement of a filter element. A case includes a first tubular portion and a second tubular portion positioned with a lower side of the first tubular portion. The second tubular portion has a diameter smaller than that of the first tubular portion. In a state where the filter element is provided inside the case, a tubular portion of the filter element abuts on the second tubular portion. A part abutting on the second tubular portion of the tubular portion is absent of a hole. A part without abutment on the second tubular portion of the tubular portion has a plurality of holes.

A filtration system includes a filter housing and a filter cartridge. The filter housing includes a base and a cover removably coupled to the base. The cover includes a retainer. The filter cartridge has a longitudinal axis and is movable between an installed position within the filter housing and an uninstalled position outside the filter housing. The filter cartridge includes a top endplate including at least one protrusion extending upwardly away from the top endplate. The protrusion includes a tab extending radially outward from the protrusion that is structured to interact with the retainer to removably couple the filter cartridge to the cover. The filter cartridge further includes a bottom endplate and a filter media extending axially between the top endplate and the bottom endplate.

A filter device includes in a filter housing a hollow cylindrical filter element having frontal end plates, a flow opening being made in one of the end plates. In order to interlockingly secure a pipe connection piece that communicates with the flow opening, a cover has a radial collar which forms an axial stop for the pipe connection piece.

A filter of a filter device has a filter housing with a connecting side provided with a connecting element for detachably connecting the filter to a filter head of the filter device by a rotational and/or insertion movement relative to an imaginary connecting axis of filter and filter head. The filter housing has an inlet for fluid to be purified and an outlet for purified fluid. An outer seal seals a connection of the filter with the filter head relative to the environment. The outer seal is circumferentially continuous relative to the connecting axis. A closure element is provided to close off, when the filter is connected to the filter head, a fluid drain in the filter head provided for draining fluid when removing the filter from the filter head. The outer seal is acting sealingly at least in radial direction relative to the connecting axis.

A filter device includes in a filter housing a hollow cylindrical filter element having frontal end plates. A port having a first sealing element is incorporated into a cover the filter housing, said sealing element being arranged coaxially relative to a second sealing element in a flow opening in the end plate.

A water purifier structure includes a container assembly and a buffer unit mounted in the container assembly. The container assembly includes a housing and a cap unit. The housing has a first receiving section and a second receiving section. The second receiving section of the housing is provided with a retaining portion. The buffer unit is mounted in the second receiving section of the housing and includes a positioning ring secured in the retaining portion of the housing, and a cushioning member mounted in the positioning ring. The cushioning member is elastically movable in the positioning ring. When the cushioning member is compressed by a force, the cushioning member is contracted and elastically deformed toward the second receiving section of the housing, to form a buffering force.

A backflow of liquid inside a filter device during an operation of an internal combustion engine is allowed to be obviated while air inside the filter device is purged so as not to generate bubbles in the liquid. An outflow portion that includes a cylindrical portion having a substantially bottomed cylindrical shape and a back pressure valve provided inside the cylindrical portion is provided so as to penetrate a bottom surface of a case. In addition, a lid body provided on the case and an upper plate of a filter element so as to cover an upper end of the case has a first hole that communicates between a space inside the case and a space outside the case. When the back pressure valve opens (a valve body does not abut on a first valve seat), a space inside the filter element communicates with the space outside the case via a second through-hole formed in a side surface of the cylindrical portion.

A filter device allows avoiding liquid and dust before filtration to flow out to a tank during replacement of a filter element. A case includes a first tubular portion and a second tubular portion positioned with a lower side of the first tubular portion. The second tubular portion has a diameter smaller than that of the first tubular portion. In a state where the filter element is provided inside the case, a tubular portion of the filter element abuts on the second tubular portion. A part abutting on the second tubular portion of the tubular portion is absent of a hole. A part without abutment on the second tubular portion of the tubular portion has a plurality of holes.

A filter system for liquid has a filter head with drainage channel and stop element. A filter cartridge is mounted by screw-in movement at the filter head and has a support ring rotatably fastened to its housing part. The support ring has an eccentric closure element and a first positioning element guided toward the stop element by the screw-in movement to position the support ring at the filter head in a rotational position for axially aligning closure element and drainage channel. The closure element is transferred axially into a sealing seat at the filter head to close the drainage channel when screwing on the filter cartridge. The support ring has a second positioning element holding the support ring in a rotationally fixed position at the filter head when unscrewing the filter cartridge so that the closure element is moved out of the sealing seat only in an axial direction.