Patent Description:
Media tanks are typically used in water treatment systems, for example, point-of-entry ion exchange water softening systems. Such media tanks are used to house one or more beds of media (for example, an ion-exchange resin or granular activated carbon media) through which water containing impurities (for example, water having an undesirably high dissolved mineral content, referred to as "hard" water) is circulated. As the water passes through the media bed or beds, the undesirable impurities (e.g. calcium and magnesium) are removed from the water, resulting in softened and/or filtered water. <CIT> discloses a fluid treatment tank having a distributor plate that includes an outer ring that is affixed to the wall of the tank and that is formed of a first thermoplastic material having a relatively low dimensional predictability, and an inner disk that is supported on the outer ring and that is formed from a second thermoplastic material having a relatively high dimensional predictability when compared to that of the first thermoplastic material, the inner disk being fluid permeable but fluid treatment media impermeable. Also disclosed is a method of assembling a pressure vessel. <CIT>, <CIT> and <CIT> show other relevant documents.

A media tank includes a housing having a first housing portion coupled to a second housing portion at an interface between the first and second housing portions, the first and second housing portions collectively defining an interior volume of the housing, and a divider positioned within the interior volume of the housing at the interface between the first and second housing portions to separate the interior volume into a first chamber at least partially defined by the first housing portion and the divider and a second chamber at least partially defined by the second housing portion and the divider. The first housing portion is coupled to the second housing portion via a friction weld at the interface. An annular gap is provided between the divider and the first housing portion. Flash from the friction weld is received within the annular gap. The divider is provided at an axial position that is aligned with the interface.

The interface may include a planar, annular surface of the first housing portion abutted against a planar, annular surface of the second housing portion. The divider may be a water-permeable divider configured to allow water to flow therethrough. The divider may include a support structure and a cloth insert coupled to the support structure. The support structure may include a plurality of ring supports extending from a central axis to an outer ring support. The cloth insert may be water permeable. The media tank may further comprise a cylindrical passage defined by the divider and connecting the first chamber to the second chamber, bypassing the cloth insert. The flash may be a radial seal between the outer ring support and the housing. The flash may be entirely located radially outward of the outer ring support. The divider may comprise a plurality of radial protrusions positioned within a recess in the housing to maintain an axial alignment of the divider with the interface. The divider may be configured to float relative to one of the first and second housing portions prior to the creation of the friction weld. The media tank may further comprise a radial seal formed as an O-ring and coupled to the divider. The radial seal may be located between the divider and the housing. The flash may be a first radial seal, the media tank may further comprise a second radial seal separate from the flash, formed as an O-ring and coupled to the divider, and the second radial seal may be located between the divider and the housing.

A method of assembling a media tank includes providing a divider at an interface between a first housing portion and a second housing portion, the divider separating an interior volume defined by the first and second housing portions into a first chamber and a second chamber. At least one of the first and second housing portions is free to translate with respect to the divider. The method further includes friction welding the first housing portion to the second housing portion, thereby generating flash at the interface, and preventing translation between said at least one of the first and second housing portions and the divider with the flash generated at the interface. The divider is provided radially within the first and second housing portions at an axial position that is aligned with the interface.

The method may further comprise locating a radial protrusion of the divider within a recess defined by the second housing portion to maintain an axial alignment of the divider with the interface prior to friction welding the first housing portion to the second housing portion. The method may further comprise forming a radial seal. Forming the radial seal may include providing an O-ring between the divider and the housing. The method may further comprise directing the flash into an annular gap between the first housing portion and the divider.

Other features and aspects of the disclosure will become apparent by consideration of the following detailed description and accompanying drawings.

Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The disclosure is capable of supporting other embodiments and of being practiced or of being carried out in various ways.

<FIG> and <FIG> illustrate a media tank <NUM> that is elongated along a longitudinal axis 10A. The media tank <NUM> includes a divider <NUM> and a housing defined by a first housing portion <NUM> and a second housing portion <NUM>. Although the housing can be oriented with the longitudinal axis 10A vertically, horizontally, or any angle in between depending on the installation, it is illustrated in <FIG> vertically and the first housing portion <NUM> is above the second housing portion <NUM>. The media tank <NUM> is a vessel such as a water treatment vessel defining an interior volume. The divider <NUM> and first and second housing portions <NUM>, <NUM> may be made of a plastic material and, in some embodiments, may be separately produced via injection molding processes. Only a portion of the first and second housing portions <NUM>, <NUM> is shown in <FIG>.

The overall length of the media tank <NUM> (i.e., the major dimension along the longitudinal axis 10a) is chosen based on the application and use case. The divider <NUM> separates an interior volume of the media tank <NUM> into a first chamber 20A on one side of the divider <NUM> (above the divider <NUM> in <FIG>) and a second chamber 20B on the other side of the divider <NUM> (below the divider <NUM> in <FIG>). A first media (not shown) for treating water is arranged within the first chamber 20A, and a second media (not shown) for treating water is arranged within the second chamber 20B. By way of example, the first media can be an ion-exchange resin to remove hard minerals such as calcium and magnesium from the water, and the second media can be granular activated carbon to remove other contaminants from the water.

The media tank <NUM> includes an inlet 16A (illustrated in <FIG>) in communication with the first chamber 20A and an outlet 16B (also illustrated in <FIG>) in communication with the second chamber 20B. The locations of the inlet and outlet 16A, 16B may alternatively be within the sidewalls of the respective first and second housing portions <NUM>, <NUM>. Water or other liquids (for example, water having dissolved solids therein) enters the media tank <NUM> via the inlet 16A into the first chamber 20A.

The divider <NUM> includes a water permeable surface that allows water to pass therethrough. As such, the water moves from the first chamber 20A, through the divider <NUM>, and to the second chamber 20B while the divider <NUM> prevents any media from passing therethrough. The dissolved solids in the water adhere to the media in the first chamber 20A such that the water flowing into the second chamber 20B is filtered water having a reduced content of dissolved solids. The water is further filtered by the media in the second chamber 20B and exits the second chamber 20B via the outlet 16B.

In at least some cases, the flow of water through the housing <NUM> may be reversed. For example, during a regeneration of the ion-exchange media, a flow of brine water can be directed into the housing through the outlet 16B into the second chamber 20B. The flow of brine water moves from the second chamber 20B, through the divider <NUM>, and to the first chamber 20A while the divider <NUM> prevents any media from passing therethrough. Salt within the brine water displaces the adhered solids from the media in the first chamber 20A, thereby regenerating the media for further use. The displaced solids are carried away by the brine water, which exits the housing <NUM> through the inlet 16A.

The divider <NUM> is shown in greater detail in <FIG>. As shown, the divider <NUM> has a substantially circular cross-section centered on a central axis A1 that is coaxial with the longitudinal axis 10A of the media tank <NUM>. A plurality of radial supports <NUM> extend outward from the central axis A1 to an outer ring support <NUM> that at least partially defines an outer radial profile of the divider <NUM>. As shown, the divider <NUM> includes twelve equally spaced radial supports <NUM>, though more or fewer may be used to modify the stiffness of the divider <NUM>. First and second inner ring supports <NUM>, <NUM> interconnect the radial supports <NUM> at different radial distances between the central axis A1 and the outer ring support <NUM>. Collectively, the outer ring support <NUM>, the first and second inner ring supports <NUM>, <NUM>, and the radial supports <NUM> form a circular web or dart board arrangement of support panels.

A screen or cloth insert <NUM> is water permeable and extends across the circular cross-section of the divider <NUM>, filling the gaps defined between the outer ring support <NUM>, the first and second inner ring supports <NUM>, <NUM>, and the radial supports <NUM>. The insert <NUM> has a porosity or mesh sufficiently tight to prevent the filter media from moving from the first chamber 20A to the second chamber 20B across the filter <NUM>. In some embodiments, the screen <NUM> is a polyethylene fabric. In some embodiments, the screen <NUM> is insert-molded within the divider <NUM>. In other embodiments, the screen <NUM> is integrally formed from the same material as the rest of the divider <NUM>.

With continued reference to <FIG>, the divider <NUM> includes a cylindrical passage <NUM> extending axially (i.e., parallel to the central axis A1) therethrough. As shown, the cylindrical passage <NUM> is offset radially from the central axis A1 but still within the outer ring support <NUM>. In other embodiments, the cylindrical passage <NUM> may be centered on the central axis A1. The cylindrical passage <NUM> is not covered by the screen <NUM> and therefore provides a bypass passageway through the divider <NUM> and bypassing the screen <NUM>. As shown in <FIG>, a conduit or riser tube <NUM> may be positioned within the passageway <NUM> to further define the bypass passage. The riser tube <NUM> can be used to provide a fluid pathway between the second chamber 20B and the outlet 16B.

Referring now to <FIG>, the outer surface of the outer ring support <NUM> is cylindrical and includes a first end <NUM> (which is an upper end in <FIG>, <FIG>, and <FIG>) and a second end <NUM> (which is a lower end in <FIG>, <FIG>, and <FIG>). A plurality of distinct, individual, and evenly-spaced radial protrusions <NUM> extend radially outward from the cylindrical outer surface of the outer ring support <NUM>. The radial protrusions <NUM> form a support structure for at least partially maintaining the location of the divider <NUM> relative to the housing portions <NUM>, <NUM>. In alternative embodiments, the distinct, radial protrusions <NUM> are replaced by a single protrusion extending outward along most or all of the circumference of the outer ring support <NUM>.

Also as seen in <FIG>, a circumferential channel <NUM> extends around the outer circumference of the outer ring support <NUM> near the second end <NUM>. The circumferential channel <NUM> is axially offset from the radial protrusions <NUM>. As seen in <FIG>, the circumferential channel <NUM> defines a seat for a radial seal <NUM>, such as an O-ring, which assists in sealing the radial interface between the divider <NUM> and the first and second housing portions <NUM>, <NUM>. The radial seal <NUM> prevents the undesirable migration of media from the first chamber 20A to the second chamber 20B. However, as will be described in further detail below, in some embodiments the radial seal <NUM> is not necessary and can be optional.

As shown in <FIG> and <FIG>, the first housing portion <NUM> and the second housing portion <NUM> are formed initially as separate, distinct components. By way of example, the housing portions <NUM> and <NUM> can both be injection molded plastic components. The first housing portion <NUM> has an axial extent or interfacing end <NUM>. The second housing portion <NUM> likewise includes an axial extent or interfacing end <NUM> that is configured to be positioned against the interfacing end <NUM> of the first housing portion <NUM>. The first and second housing portions <NUM>, <NUM> abut against one another at the interfacing ends <NUM>, <NUM> to define an interface between the two housing portions <NUM>, <NUM>. The two interfacing ends <NUM>, <NUM> are planar, annular surfaces that mate flush against one another, ready for a friction welding operation (e.g., friction stir welding) to couple the two housing portions <NUM>, <NUM> together.

With the interfacing ends <NUM>, <NUM>, positioned against one another, the inner cylindrical walls <NUM>, <NUM> of the first and second housing portions define the interior volume of the housing <NUM>, <NUM>. One or both of the inner walls <NUM>, <NUM> includes a radial recess <NUM> where the generally cylindrical wall(s) <NUM>, <NUM> is radially offset to define a channel. As shown, the radial recess <NUM> is axially aligned with the interface <NUM>, <NUM> between the two housing portions <NUM>, <NUM>. As shown in <FIG>, the radial protrusions <NUM> are positioned within the radial recess <NUM>, thereby supporting the divider <NUM> between the two housing portions <NUM>, <NUM>. More specifically, the divider <NUM> is supported at the interface <NUM>, <NUM> between the two housing portions <NUM>, <NUM>. The divider <NUM> is held in an axial position that is aligned with the interface <NUM>, <NUM> such that the interface <NUM>, <NUM> is located at an axial position that is between the location of the ends <NUM> and <NUM> of the divider plate <NUM>.

With a media tank <NUM> formed of two housing halves <NUM>, <NUM>, such as a tank <NUM> formed via an injection molding process, the two housing portions <NUM>, <NUM> are made separately, then welded together to form the vessel. In a vibration welding process, the oscillation amplitude of the housing portions <NUM>, <NUM> is great enough to sheer off the divider <NUM> if the divider is rigidly located within the weld. Additionally, too much motion of the divider in the friction welding process may result in damage to the screen <NUM>. The protrusions <NUM> are located within that portion of the radial recess <NUM> that is defined by the housing portion <NUM>, with minimal radial clearance between the outward facing edges of the protrusions <NUM> and the cylindrical wall of the housing portion <NUM>. Accordingly, movement of the divider <NUM> relative to the housing portion <NUM> is fairly restricted. Particularly in the case where the radial seal <NUM> is present, the allowable movement of the divider <NUM> relative to the housing portion can be minimal. In contrast, the inner cylindrical wall <NUM> of the housing portion <NUM> is located entirely above the protrusions <NUM>, such that the annular gap between the wall <NUM> and the outwardly facing cylindrical wall of the outer ring support <NUM> of the divider <NUM> leaves the divider <NUM> free to translate, with respect to the housing portion <NUM>, in a plane that is perpendicular to the axis A1. In other words, the divider <NUM> is able to float relative to the housing portion <NUM>. The use of the term "float" identifies that the divider <NUM> is not rigidly tied down to the housing portion <NUM>. In some embodiments, the divider <NUM> may be capable of minor axial movement and may be rotatable when positioned between the two housing portions <NUM>, <NUM> (when the two housing portions <NUM>, <NUM> are not yet fastened together).

To prepare the assembly for friction welding, the housing portion <NUM> is rigidly secured, with the divider <NUM> inserted into the recess. In the friction welding process, heat generated by rotating/oscillating the housing portion <NUM> relative to the other housing portion <NUM> generates flash. The flash is the excess material that melts and is extruded away from the weld interface <NUM>, <NUM>. In welding the housing <NUM>, <NUM> of the media tank <NUM>, at least some of the welding flash <NUM>, as a byproduct of the welding process, is forced inward at the interface <NUM>, <NUM> into the radial space between the inner walls <NUM>, <NUM> of the housing <NUM>, <NUM> and the divider <NUM>. The outer ring support <NUM> has a sufficient axial length and thickness to force the flash <NUM> to buckle and fold against the outer profile of the outer ring support <NUM>. This arrangement not only manages the flash <NUM> generated by the welding process, but also forms an outer, radial seal around the divider <NUM> to prevent at least some media from circumventing the screen <NUM>. The O-ring <NUM> positioned within the channel <NUM> acts as a further radial seal and may additionally dampen the vibration against the tank walls <NUM>, <NUM> and trap and keep flash <NUM> from leaking below the divider <NUM>.

During the friction welding process, the clearance between the housing portion <NUM> and the divider <NUM> allows for sufficient movement of the housing portion <NUM> (relative to both the housing portion <NUM> and the divider <NUM>) to create the heat necessary for welding together housing portions and creating the flash <NUM>. In some embodiments, the flash <NUM> may fill gaps within the recess <NUM> such that the constrained motion of the divider <NUM> within the recess <NUM> is further constrained by the flash <NUM> as a result of the friction welding process. The flash <NUM> may extend axially around the protrusion <NUM>, as shown in <FIG>, thereby limiting axial movement of the divider <NUM> relative to the housing <NUM>, <NUM>. Further, the flash may extend between the different protrusions <NUM> (that are spaced about the circumference of the divider <NUM>), thereby further constraining the relative rotation between the divider <NUM> and the housing <NUM>, <NUM>. The annular gap can advantageously be sized to accommodate the flash <NUM> such that the flash <NUM> does not extend radially inward beyond the outer ring <NUM>, so that the flow of water through the screen <NUM> is not obstructed by flash.

In some embodiments, the outer walls of the housing <NUM>, <NUM> may form a pocket <NUM> adjacent the interface <NUM>, <NUM>. The pocket <NUM> is located outside of the interior volume of the media tank <NUM>, located radially outward from the interface <NUM>, <NUM>. In some embodiments, the pocket <NUM> may retain any flash that flows radially outward during the friction welding process <NUM> such that an outer profile of the media tank <NUM> lacks any visible flash. With no visible external flash, postprocessing steps for cleaning up the flash are eliminated.

In operation, assembling the media tank <NUM> includes forming a first housing portion <NUM>, a second housing portion <NUM>, and a divider <NUM>. The components of the media tank <NUM> may be formed by, for example, injection molding. The divider <NUM> may be further assembled by incorporating the cloth insert <NUM> and the radial seal <NUM> into the support structure <NUM>, <NUM>, <NUM>, <NUM>. The divider <NUM> is positioned within the housing <NUM>, <NUM>, with the radial protrusions <NUM> located within the radial recess <NUM>. The two housing portions <NUM>, <NUM> are positioned adjacent one another such that the respective interfacing ends <NUM>, <NUM> abut against one another. In this arrangement, the divider <NUM> is supported within the housing portion <NUM> and is axially aligned with the interface <NUM>, <NUM>, and is floating with respect to the housing portion <NUM>. The two housing portions <NUM>, <NUM> are fused together via a friction welding process, with relative rotational and/or oscillating motion between the housing portions <NUM>, <NUM> generating heat and flash <NUM>. The flash <NUM> is displaced in the welding process away from the interface <NUM>, <NUM> and into the radial space between the housing <NUM>, <NUM> and the divider <NUM>. With the welding process completed and the housing portions <NUM>, <NUM> fused together, the flash <NUM> cools, forming a radial seal between the housing <NUM>, <NUM> and the divider <NUM>.

The media tank <NUM> is therefore separated into the first chamber 20A defined primarily by the first housing portion <NUM> and the divider <NUM> and the second chamber 20B defined primarily by the second housing portion <NUM> and the divider <NUM>. The flash <NUM> generated by the welding process provides a radial seal that precludes at least some media from passing around the divider <NUM> and bypassing the screen <NUM>. As such, the divider <NUM> is capable of separating the media from the water with increased efficiency.

Claim 1:
A media tank (<NUM>) comprising:
a housing having a first housing portion (<NUM>) coupled to a second housing portion (<NUM>) at an interface between the first and second housing portions, the first and second housing portions collectively defining an interior volume of the housing; and
a divider (<NUM>) positioned within the interior volume of the housing at the interface between the first and second housing portions to separate the interior volume into a first chamber (20A) at least partially defined by the first housing portion and the divider and a second chamber (20B) at least partially defined by the second housing portion and the divider,
characterized in that,
the divider is provided at an axial position that is aligned with the interface,
the first housing portion is coupled to the second housing portion via a friction weld at the interface,
an annular gap is provided between the divider and the first housing portion, and
flash (<NUM>) from the friction weld is received within the annular gap.