Abstract:
A free ink marking instrument for dispensing a fluid is disclosed. The instrument includes a feeder, a passage of reduced capillarity surrounding the feeder for conveying at least one of fluid and air to the reservoir during an increasing pressure differential between air in the reservoir and the atmosphere, a porous buffer configured for storing ink during periods of a decreasing pressure differential between air in the reservoir and the atmosphere, and a divider tube separating the buffer and the passage along a majority of the length of the buffer. The fluid and air may enter the feeder through a minor surrounding portion of the buffer during the period of the increasing pressure differential. An ink and air conveyor for use in a free ink marking instrument is also disclosed. A method for compensating for changes in ambient temperature and pressure in a free ink marking instrument is also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a division of co-pending U.S. patent application Ser. No. 09/498,913, titled “FREE INK SYSTEM,” filed Feb. 4, 2000, which is hereby incorporated by reference. The following patent application is cited by reference and incorporated by reference herein: German Patent Application No. 199 30 540.4 titled “HAND-AUFTRAGGERÄT,” filed Jun. 28, 1999. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to a marking utensil. In particular, the present invention relates to a marking utensil that provides hydrostatic stability in response to changes in temperature and pressure. 
     BACKGROUND OF THE INVENTION 
     It is well known to provide a pen having free ink that a user may selectively apply to a substrate such as paper. Such known pens typically include a reservoir for storing the ink and a channel for ducting the ink from the reservoir to a marking tip. The ink of such known pens typically has a vapor pressure such that the ink, and any air in the reservoir, expands and contracts in response to changes in ambient temperature and pressure. Such expansion and contraction of air may cause the ink to leak from the writing tip of the pen. 
     Other such known pens include a buffer for storing excess ink in response to changes in ambient temperature and pressure. The excess ink is typically stored in the front of the buffer near the tip of the pen (i.e., due to gravity). However, such known pens have several disadvantages: the ink capacity of the buffer is limited such that when the buffer is full the excess ink from the pen, and the ink is often permanently stored in the buffer resulting in decreased buffer capacity and wasted ink. Another of such known pens provides for the cleaning of ink from the buffer when the pressure inside the pen is increased by venting air into the pen through an external vent. Such known pens, however, only clean a small portion of the buffer. 
     Accordingly, it would be advantageous to provide a hydrostatically stable pen that responds to repeated temperature and pressure changes by reducing the accumulation of ink in the buffer without substantially leaking or dripping. It would also be advantageous to provide a pen that optimizes the efficiency of the buffer by purging the buffer during changes in ambient temperature or pressure. It would also be advantageous to provide hydrostatic stability when the pen is oriented in any direction. Other advantages of the subject matter recited in the appended claims will become apparent to those skilled in the art upon review of the specification and the claims. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a free ink marking instrument for dispensing a fluid including a housing having an interior defined by a wall and a reservoir for storing the fluid disposed in the housing. The instrument includes a feeder for conveying fluid to a marking tip from the reservoir. The instrument also includes a passage of reduced capillarity relative to the feeder surrounding the feeder for conveying at least one of fluid and air to the reservoir during an increasing pressure differential between air in the reservoir and the atmosphere. The instrument also includes a porous buffer disposed between the wall of the housing and the passage and configured for storing ink during periods of a decreasing pressure differential between air in the reservoir and the atmosphere. The instrument also includes a divider tube separating the buffer and the passage along a majority of the length of the buffer. The fluid and air may enter the feeder through a minor surrounding portion of the buffer during the period of the increasing pressure differential. 
     The present invention also relates to an ink and air conveyor for use in a free ink marking instrument for dispensing ink onto a substrate such as paper. The instrument includes a housing having an interior including a reservoir for storing the ink and a marking tip coupled to the housing. The conveyor includes a divider tube supported along an axis of the marking instrument. The conveyor also includes a feeder disposed within the divider tube and extending outwardly therefrom toward the marking tip. The conveyor also includes a buffer surrounding a portion of the feeder and extending outwardly from the divider tube. The conveyor also includes a channel adapted for conveying at least one of fluid and air located between an exterior surface of the feeder and an interior surface of the divider tube. 
     The present invention also relates to a method for compensating for changes in temperature and pressure in a free ink marking instrument. The instrument includes a housing having an interior defined by a wall, a reservoir for storing ink and air disposed in the housing, and a marking tip coupled to the housing. The instrument also includes a buffer having a first portion and a second portion disposed within the housing and a divider tube generally parallel to the wall of the housing. The instrument also includes a feeder configured for conveying air and ink. A first portion of the feeder extends into the divider tube and is spaced from an inner wall thereof. A second portion of the feeder is attached to an inner wall of the divider tube, and a third portion of the feeder extends outwardly from the divider tube toward the marking tip. The method includes drawing air from the atmosphere through a vent near the marking tip to the interior of the housing during periods of increasing ambient pressure or decreasing ambient temperature. The method also includes urging the air through the buffer. The method also includes urging the air from the buffer to the third portion of the feeder. The method also includes urging the air from the third portion of the feeder to the channel. The method also includes urging the air from the feeder to a space between the feeder and the inner wall of the divider tube. 
    
    
     DESCRIPTION OF THE FIGURES 
     FIG. 1 is a perspective view of a marking instrument according to an exemplary embodiment of the present invention. 
     FIG. 2 is a cross-sectional view of the marking instrument of FIG. 1 taken along line  2 — 2  of FIG.  1 . 
     FIG. 3 is a cross-sectional view of the marking instrument of FIG. 1 taken along line  3 — 3  of FIG.  2 . 
     FIG. 4 is a cross-sectional view of the marking instrument of FIG. 1 according to an alternative embodiment of the present invention. 
     FIG. 5 is a cross-sectional view of the marking instrument of FIG. 4 taken along line  5 — 5  of FIG.  4 . 
     FIG. 6 is a cross-sectional view of the marking instrument of FIG. 1 according to an alternative embodiment of the present invention. 
     FIG. 7 is a cross-sectional view of the marking instrument of FIG. 6 taken along line  7 — 7  of FIG.  6 . 
     FIG. 8 is an enlarged cross-sectional view of the marking instrument of FIG. 4 along line  8 — 8  of FIG. 4 according to a particularly preferred embodiment. 
     FIG. 9 is an enlarged fragmentary cross-sectional view of a bubble separation area of the marking instrument of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a writing or marking utensil such as a pen or a highlighter (shown as a marker  10 ) according to an exemplary embodiment of the present invention. Marker  10  includes a body  12  disposed between a writing end  14  and a butt end  16 . A removable cap  18  having a clip  20  is shown attached to writing end  14  of body  12 . Cap  18  may be sized to engage end  16  for storage of cap  18  during use of marker  10 . According to any preferred or alternative embodiment, a flexible or rigid grip  22  surrounds at least a portion of body  12 . 
     FIG. 2 shows a cross-sectional view of marker  10  according to an exemplary embodiment. Marker  10  includes a housing  30  provided by an exterior wall  32 , which defines an interior of marker  10 . Housing  30  also provides a reservoir  34  for storing free ink  38 . The term “free ink” is defined as liquid ink that may be stored in a cavity and that is free to move or flow in response to external forces (e.g., motion, gravity, pressure, etc.). A user may view such free ink in a column of a writing utensil to determine how much ink is available for use. An ink transfer element or interior channel (shown as a feeder  46 ) is in fluid communication with reservoir  34  and provides a conduit for transferring ink  38  from reservoir  34  to a marking or writing tip  92 . An open channel or feed tube (shown as a passage  60 ) and an adapter  66  are located about an upper section  48  of feeder  46 . A plenum (shown as a head  70 ) of adapter  66  separates reservoir  34  from the lower portion of marker  10  and secures an inner non-porous divider tube  68  around passage  60 . The generally cylindrical interior of adapter  66  is larger than the generally cylindrical upper section  48  of feeder  46  so that passage  60  is in fluid communication with reservoir  34 . A buffer  80  surrounds divider tube  68  and at least a portion of a lower section  52  of feeder  46  (see FIG.  3 ). 
     Reservoir  34  provides an area for storing ink  38  as shown in FIG. 2. A headspace  36  of air and vapor is located above ink  38 , which expands and contracts in response to changes in temperature and pressure. Ink  38  in reservoir  34  typically has a relatively high vapor pressure, so that it can dry quickly when used, and responds significantly to changes in temperature and pressure. A variety of inks such as solvent based (e.g., alcohol) or water based inks may be used with the writing utensil, and the physical properties of different inks may dictate slight differences in the writing instrument (e.g., shapes, sizes, geometries, etc.). According to alternative embodiments, the ink may be water-based and may contain pigments, such as those inks used in MAJOR ACCENT® highlighters and liquid paint felt tip marking and coloring applicators commercially available from Sanford Corporation of Bellwood, Ill. According to other alternative embodiments, the ink may be alcohol and dye based such as those inks used in SHARPIE® marking and writing pens commercially available from Sanford Corporation of Bellwood, Ill. According to still other alternative embodiments, the ink may be alcohol and pigment based such as those inks used in EXPO™ and EXPO 2 ™ white board marker pens and dry erase marking pens commercially available from Sanford Corporation of Bellwood, Ill. According to a preferred embodiment, the ink is compatible with a plastic material such as polypropylene. 
     Head  70  of adapter  66  may be held by interference fit within housing  30  as shown in FIG.  2 . Divider tube  68  of adapter  66  limits the engagement between feeder  46  and buffer  80 , such that buffer  80  and feeder  46  may be in direct contact near lower section  52  of feeder  46 . The length of adapter  66  also limits the location where ink  38  from reservoir  34  has access to buffer  80  (i.e., at a bubble separation area  42 ). According to a preferred embodiment as shown in the FIGURES, divider tube  68  has a length greater than passage  60 . According to a particularly preferred embodiment as shown in the FIGURES, head  70  of adapter  66  is integral with divider tube  68  to form a unitary, molded piece. Divider tube  68  is preferably made of a plastic, such as polypropylene, which is generally compatible with ink  38 . Passage  60  is preferably tubular, and provides a substantially resistance free path for air and ink to travel from feeder  46  to reservoir  34 . According to alternative embodiments, the passage may be any of a variety of shapes, at least in part depending on the shape of the feeder and the adapter. 
     Feeder  46  includes upper section  48  having a first diameter  54 , an intermediate section  50  having a second and larger diameter  56 , and lower section  52  having a third and still larger diameter  58 . Intermediate section  50  includes a ridge (shown as a shoulder  51 ) that is located proximate a lower end  64  of passage  60 . Lower section  52  also includes a ridge (shown as a shoulder  55 ) located proximate lower end  64  of divider tube  68 . Upper section  48  extends from head  70  to shoulder  51  and may be substantially equal in length to passage  60 . Intermediate section  50  extends from shoulder  51  to shoulder  55 , and lower section  52  extends from shoulder  55  to tip  92 . Shoulder  55  abuts against lower end  62  of divider tube  68  and prevents feeder  46  from being pushed or moved toward reservoir  34  during the act of writing with marker  10 . Intermediate section  50  is engaged against divider tube  68 , divider tube  68  is engaged in an interference fit against buffer  80 , and head  70  is engaged in an interference fit against housing  30 . Feeder  46  may be integral with tip  92  as shown in FIG. 2, or according to an alternative embodiment as shown in FIG. 4, feeder  46  may be a separate piece from tip  92  (shown located outside of buffer  80 ). 
     Feeder  46  and tip  92  are preferably comprised of synthetic resin fibers  94  oriented in a generally vertical direction as shown in FIG.  2 . According to a preferred embodiment, fibers  94  are irregular shaped and are somewhat randomly distributed in the feeder. Thus, spaces or capillaries (not shown) are provided somewhat randomly distributed between fibers  94  so that air and ink may pass between fibers  94  (i.e., air may enter and exit feeder  46  and tip  92  between the spaces of fibers  94 , unless the spaces are saturated with ink). According to a preferred embodiment as shown in FIG. 3, feeder  46  has a circular shaped cross-section. According to other alternative embodiments, the feeder may have a variety of shaped cross-sections (e.g., toothed, jagged, smooth, etc.). According to a preferred embodiment, the ink transfer element (i.e., feeder  46 ) is made of an acrylic material (model no. AE553C) or a polyester material (model no. ET-150N) commercially available from Teibow Co. Ltd. of Hamamatsu-shi, Shizuoka-ken, Japan. According to an alternative embodiment, the ink transfer element and the tip may be made of felt or synthetic resin foam. 
     A nib section  90  attaches tip  92  to housing  30  as shown in FIG.  2 . Nib section  90  provides stability and support to feeder  46  and to tip  92 . Tip  92  is shown in the FIGURES having a parabolic shape. According to other alternative embodiments, tip  92  may have a variety of shapes such as a chisel shape, a chisel with an angle, pointed or rounded shapes, etc. Without intending to be limited to any particular theory, it is believed that the larger the surface area of the tip, the lower the capillary pressure of the tip when it is saturated with ink. Such reduced capillary pressure of the tip is described by LaPlace, who theorizes that the pressure across an interface is proportional to the surface tension of the liquid and inversely proportional to the mean radius of curvature of such liquid. The LaPlace equation is described in U.S. Pat. No. 4,753,546 issued to Witz et al. 
     For proper function of the marker  10 , the capillarity of tip  92  should be greater than the capillarity of either feeder  46 , buffer  80 , or passage  60 . The term “capillarity” can be defined as the height to which a liquid (e.g., ink) ascends within a pore of a capillary having a given height and diameter, and includes the attractive capillary force (i.e., capillary pressure) of the liquid to the capillary. Without intending to be limited by any particular theory, it is believed that capillary force is inversely proportional to both the pore size of a capillary and the storage capacity of a capillary. According to a preferred embodiment of the present invention, tip  92  has a greater capillarity than that of feeder  46 , feeder  46  has a greater capillarity than that of buffer  80 , and buffer  80  has a greater capillarity than that of passage  60 . Thus, tip  92  remains wet with ink  38  regardless of the ink distribution inside marker  10 , such that marker  10  is always ready to make marks on the substrate during the act of writing. 
     Buffer  80  may be porous and includes a volume sufficient for retaining ink  38  and air in response to changes in temperature or pressure within reservoir  34 . If the ink-retaining capacity of buffer  80  is not exceeded, then the capillary pressure of buffer  80  will retain excess ink  38 . An air intake (shown as an air entry hole  96 ) in housing  30  may provide an air vent in communication with the atmosphere. (Air may also enter marker  10  through capillary spaces surrounding writing tip  92 .) A space for holding air (shown as a gap  86 ) surrounds an exterior surface  88  of buffer  80 . Air from hole  96  may enter buffer  80  through external surface  88 . The size of buffer  80  may be selected in accordance with the air volume of marker  10  needed to hold the quantity of excess ink. For overall hydrostatic stability, the capillarity of buffer  80 , the capillarity of feeder  46 , and the capillarity of passage  60  are selected so that marker  10  does not substantially leak in response to changes in temperature and pressure. According to a preferred embodiment, buffer  80  has a capacity of about 40% relative to the size of reservoir  34 . According to a particularly preferred embodiment, buffer  80  may retain or store about 2.8 ml of ink. Buffer  80  may be made of a variety of fibrous or porous materials, and its porosity and capillary nature may be selected for compatibility with the particular ink used in the writing utensil. According to a particularly preferred embodiment of the present invention, the buffer is made from a hydrophilic (model no. D-2605) or a hydrophobic (model no. D-2611) linear polyolefin fiber resin commercially available from Filtrona Richmond, Inc. of Richmond, Va. According to alternative embodiments, buffer  80  may be made of ceramics, porous plastics such as open cell foams, acrylics, sponges, etc. According to other alternative embodiments, buffer  80  may be made of hydrophilic or hydrophobic foam, such as polyurethane. 
     The air and vapor in reservoir  34  responds to changes in pressure and temperature. At equilibrium, the pressure of the air and vapor in reservoir  34  is at a pressure slightly less than ambient pressure, due to the height of ink  38  in reservoir  34  above tip  92 . The term “ambient pressure” is defined as the pressure of the atmosphere outside of the marker. At such slightly lower pressure of air and vapor in reservoir  34 , ink  38  is retained in marker  10 . To begin the act of writing with marker  10 , ink  38  is ducted from reservoir  34  through feeder  46  to tip  92 . If any ink is stored in buffer  80  during writing, such stored ink is preferentially taken by feeder  46  because of the greater capillarity of feeder  46  relative to buffer  80 . 
     When cap  18  is removed from body  12 , marker  10  responds to changes in ambient pressure and ambient temperature (i.e., pressure and temperature differentials) to reach equilibrium (i.e., the pressure slightly less than ambient pressure). The term “pressure differential” is defined as the difference in pressure between the air and vapor inside reservoir  34  and ambient pressure. The term “increasing pressure differential” is defined as the increase in pressure of the air and vapor inside reservoir  34  in response to an increasing ambient pressure. The term “decreasing pressure differential” is defined as the decrease in pressure of the air and vapor inside reservoir  34  in response to a decreasing ambient pressure. Without intending to be limited to any particular theory, it is believed that the air and vapor inside the marker responds “directly” to changes in ambient pressure and temperature to reach equilibrium. 
     An increasing pressure differential situation occurs, for example, during a “descent” in a pressurized airplane. If ink  38  is stored in buffer  80  during an increasing pressure differential situation, then, feeder  46  seeks ink  38  from buffer  80  and passage  60  seeks ink from feeder  46 . If buffer  80  is substantially free of ink  38  during an increasing pressure differential situation, then feeder  46  seeks air from buffer  80  and passage  60  seeks air from feeder  46 . Ink and air flow behaves similarly when a user writes with and discharges ink  38  onto a substrate (e.g., paper, cloth, marker board, etc.). 
     During an increasing pressure differential situation (or decreasing temperature differential situation) where buffer  80  is near empty (i.e., substantially free of ink  38 ), the difference in pressure between the air and vapor in reservoir  34  and ambient pressure may become so great that a bubble pressure of marker  10  is reached. The term “bubble pressure” is defined as the pressure differential necessary to draw or vent external air through hole  96 , through buffer  80 , feeder  46 , passage  60  and ultimately into reservoir  34 . Such venting of air adds to the volume of air in reservoir  34  to maintain the pressure differential between air in reservoir  34  and ambient conditions outside of marker  10  at a relatively constant level. The vented air is preferentially drawn through passage  60  into reservoir  34  (rather than through feeder  46 ) because passage  60  has a larger capillary space, and thus lower resistance, available for the air than does feeder  46 . The increasing pressure differential transports ink  38  and/or air, while tip  92  remains wet with ink  38  for quick writing and reduced leakage. 
     As ambient pressure and temperature changes, the air inside reservoir  34  will expand and contract and accordingly force ink  38  out of (or pull ink into) a vent channel  44  (shown in phantom lines in FIG.  9 ). If insufficient ink exists in the buffer during an increasing pressure differential situation, air (shown as bubbles  40 ) enters vent channel  44  and creates the desired equilibrium. During such increasing pressure differential situation, air will first urge ink out of buffer  80 , and then will follow the path of least resistance and will accordingly migrate toward lower section  52  of feeder  46 . The air will then travel through and along feeder  46  and will enter passage  60  (since air does not substantially enter the feeder through adapter  66  or divider tube  68 ). 
     Marker  10  may also experience a decreasing pressure differential situation. A decreasing pressure differential situation occurs, for example, during an “ascent” in a pressurized airplane, during which ambient pressure may decrease to about two-thirds that of normal atmospheric pressure (i.e., two-thirds of one atmosphere (760 mm mercury)). As a result of a decreasing pressure differential, air in reservoir  34  expands forcing ink  38  toward writing end  14  of marker  10 . If buffer  80  is not fully saturated with ink  38  during a decreasing pressure differential situation, then buffer  80  (due to its capillary force) will absorb excess ink from reservoir  34 . Since marker  10  can compensate for both increasing and decreasing pressure and temperature differentials, the hydrostatic balancing of air in the marker  10  may be achieved to provide a constant ink flow, and to inhibit ink from dripping or leaking from tip  92  when marker  10  is oriented in any direction (e.g., horizontal, vertical, etc.). 
     Feeder  46  includes bubble separation area  42  as shown in FIGS. 2 and 9. Bubble separation area  42  is located between a lower end  82  of buffer  80  and shoulder  51  to allow bubbles  40  to form and rise to the surface of ink  38  in reservoir  34 . The length of bubble separation area  42  in a preferred embodiment is in the range of about 2-6 mm, most preferably about 2-4 mm, and still more preferably about 3-4 mm. The location of bubble separation area  42  near tip  92  functions to purge lower end  82  of buffer  80  of ink  38  during an increasing pressure differential situation. The location of bubble separation area  42  is advantageous for at least two reasons: it assists in more completely emptying or purging buffer  80  of ink  38 ; and it reduces the accumulation of ink  38  in lower end  82  of buffer  80 , which may contribute to leakage of ink  38  from marker  10 . 
     FIGS. 4 through 5 show a marker  110 , an alternative embodiment of marker  10 . Marker  110  is modified from marker  10  in two respects: the shape of feeder  46  is changed, and capillaries  160  replace passage  60 . Other than these modifications, the construction and performance of marker  110  is substantially identical to that of marker  10 , and like reference numerals are used to identify like elements. Referring to FIG. 4, a feeder  146  includes a lower section  152  and an upper section  150  having a shoulder  151 . Shoulder  151  abuts against divider tube  68 . Lower section  152  has a diameter  158  greater than a diameter  156  of section  150 . Section  150  may include an apex (shown as a point  154 ) in a fluid exchange relationship to capillaries  160 . Point  154  increases the surface area of the interface between section  150  of feeder  146  and capillaries  160  (see FIG.  5 ). Capillaries  160  are molded or cut into head  70  and divider tube  68  of adapter  66  to form corner sections (shown as grooves  168  in FIG.  8 ). Grooves  168  may be formed from a saw-shaped protrusion (shown as a jagged protrusion  164 ) or from a smooth protrusion (shown as a rectangle  166 ). Grooves  168  function as capillaries for transporting both air and ink between reservoir  34  and tip  92 . 
     FIGS. 6 through 7 show a marker  210 , an alternative embodiment of marker  110 . Marker  210  is modified from marker  110  in two respects: capillaries  160  have been omitted, and the diameter of marker  210  is of a reduced size. Other than these modifications, the construction and performance of marker  210  is substantially identical to that of marker  110 , and like reference numerals are used to identify like elements. Referring to FIG. 6, a passage  260 , similar to passage  60 , is surrounded by adapter  66  and divider tube  68 . Upper section  150  of feeder  146  is in fluid communication with ink  38 . Bubbles  40  may be formed at the interface between point  154  of feeder  146  and the ink in passage  260 . Passage  260  provides a channel for conveying ink  38  from reservoir  34  to writing tip  92 , and a channel for conveying bubbles  40  from gap  86  to reservoir  34 . Referring to FIG. 7, marker  210  has a smaller overall diameter than the overall diameter of marker  110 . Thus, marker  210  holds less ink than marker  110 , and the size of a buffer  280  of marker  210  is smaller than the size of buffer  80  of marker  110 . 
     According to a particularly preferred embodiment, the marker  10  may be sized to hold about 7.0 ml of ink, the buffer may be sized to hold about 2.8 ml of ink, and the reservoir may be sized to hold about 4.0-5.0 ml of air. The length of the marker  10  is preferably about 5.0 inches. The butt end of the marker  10  preferably has a diameter of about 0.5 inches and the midsection of the marker  10  preferably has a diameter of about 0.8 inches. The marker  10  preferably has a generally triangular cross-section. 
     It is important to note that the construction and arrangement of the elements of the writing utensil shown in the exemplary embodiments is illustrative only. Although only a few exemplary embodiments of the present invention have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (such as variations in sizes, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, etc.) without materially departing from the novel teachings and advantages of the invention. According to alternative embodiments, the size of the capillaries, feeders, passages, tips or buffers may depend on the respective construction of the writing utensil and may be determined by experimentation. The capillarity of the feeders, passages, tips, buffers and capillaries can be selected to provide for optimum performance with inks of different physical properties (e.g., viscosity, vapor pressure, etc.). Accordingly, all such modifications are intended to be included within the scope of the invention as defined in the appended claims. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred embodiments without departing from the spirit of the invention as expressed in the appended claims. 
     It is important to note that the terms “channel” is not meant as a term of limitation, insofar as the structures described in this specification (or alternative and/or equivalent structures) may serve to provide for the flow, channeling, ducting, transferring, transporting, etc. of a fluid through a passage, chamber, tube, conduit, inlet, intake, outlet, discharge, port, etc.